aarch64: feature parity with riscv64

abi/abi.zig

@@ -1,21 +0,0 @@
-pub const SyscallNumber = enum(usize) {
-    SYS_send = 1,
-    SYS_recv = 2,
-    SYS_sendrecv = 3,
-    _,
-};
-
-pub const ProcessObjectAction = enum(usize) {
-    ZO_process_exit = 1,
-    _,
-};
-
-pub const PhysicalMemoryObjectAction = enum(usize) {
-    ZO_physical_memory_allocate = 1,
-    ZO_physical_memory_free = 2,
-    _,
-};
-
-pub const MAX_SYSCALL: usize = 32;
-
-pub const Handle = enum(u32) { _ };

build.zig

@@ -6,7 +6,7 @@ const SupportedArch = enum {
     aarch64,
     riscv64,
 
-    fn make_kernel_target(self: SupportedArch, b: *std.Build) std.Build.ResolvedTarget {
+    fn make_target(self: SupportedArch, b: *std.Build) std.Build.ResolvedTarget {
         switch (self) {
             .riscv64 => {
                 return b.resolveTargetQuery(.{
@@ -38,47 +38,7 @@ const SupportedArch = enum {
         }
     }
 
-    fn make_userspace_target(self: SupportedArch, b: *std.Build) std.Build.ResolvedTarget {
-        // TODO: it's the same for now, until userspace support for CPU extensions like floating
-        //       point is added.
-        return self.make_kernel_target(b);
-    }
-
-    fn configure_user(
-        self: SupportedArch,
-        b: *std.Build,
-        user: *std.Build.Step.Compile,
-    ) anyerror!*std.Build.Step {
-        switch (self) {
-            .riscv64 => {
-                user.setLinkerScript(b.path("user/riscv64.ld"));
-            },
-            .aarch64 => {
-                user.setLinkerScript(b.path("user/aarch64.ld"));
-            },
-        }
-
-        b.installArtifact(user);
-
-        const elf2bin = b.addSystemCommand(&.{
-            "llvm-objcopy",
-            "-O",
-            "binary",
-            "zig-out/bin/userspace",
-            "zig-out/bin/userspace.bin",
-        });
-
-        elf2bin.step.dependOn(&user.step);
-
-        return &elf2bin.step;
-    }
-
-    fn configure_kernel(
-        self: SupportedArch,
-        b: *std.Build,
-        kernel: *std.Build.Step.Compile,
-        user: *std.Build.Step,
-    ) anyerror!*std.Build.Step {
+    fn add_target_specific(self: SupportedArch, b: *std.Build, kernel: *std.Build.Step.Compile) anyerror!*std.Build.Step {
         switch (self) {
             .riscv64 => {
                 kernel.entry = .{ .symbol_name = "__rv64_entry" };
@@ -101,7 +61,6 @@ const SupportedArch = enum {
             },
         }
 
-        kernel.step.dependOn(user);
         b.installArtifact(kernel);
 
         if (self == .riscv64 or self == .aarch64) {
@@ -177,44 +136,29 @@ fn insert_fake_linux_image_header(step: *std.Build.Step, opts: std.Build.Step.Ma
     _ = opts;
 }
 
+fn build_riscv64(b: *std.Build) anyerror!void {
+    _ = b;
+}
+
 pub fn build(b: *std.Build) anyerror!void {
     const maybe_arch_option = b.option(SupportedArch, "arch", "Architecture to use");
 
     const arch = maybe_arch_option orelse DEFAULT_ARCH;
-    const kernel_target = arch.make_kernel_target(b);
-    const user_target = arch.make_userspace_target(b);
+    const target = arch.make_target(b);
     const optimize = b.standardOptimizeOption(.{ .preferred_optimize_mode = .ReleaseFast });
 
-    const kernel_code_model: std.builtin.CodeModel = switch (arch) {
+    const code_model: std.builtin.CodeModel = switch (arch) {
         .riscv64 => .medium,
         .aarch64 => .small,
     };
-    const user_code_model = kernel_code_model;
-
     const kernel_module = b.addModule("kernel", .{
         .optimize = optimize,
-        .target = kernel_target,
+        .target = target,
         .pic = true,
         .red_zone = false,
-        .code_model = kernel_code_model,
+        .code_model = code_model,
         .root_source_file = b.path("src/kernel.zig"),
     });
-    kernel_module.addAnonymousImport("userspace", .{ .root_source_file = b.path("zig-out/bin/userspace.bin") });
-
-    const abi_module = b.addModule("abi", .{
-        .optimize = optimize,
-        .red_zone = false,
-        .target = kernel_target,
-        .code_model = kernel_code_model,
-        .root_source_file = b.path("abi/abi.zig"),
-    });
-    const user_module = b.addModule("userspace", .{
-        .optimize = optimize,
-        .target = user_target,
-        .red_zone = false,
-        .code_model = user_code_model,
-        .root_source_file = b.path("user/main.zig"),
-    });
     const kernel = b.addExecutable(.{
         .name = "kernel",
         .root_module = kernel_module,
@@ -223,15 +167,6 @@ pub fn build(b: *std.Build) anyerror!void {
     });
     kernel.pie = true;
 
-    user_module.addImport("abi", abi_module);
-    kernel_module.addImport("abi", abi_module);
-
-    const user = b.addExecutable(.{
-        .name = "userspace",
-        .root_module = user_module,
-        .use_lld = true,
-    });
-
     const install_docs = b.addInstallDirectory(.{
         .source_dir = kernel.getEmittedDocs(),
         .install_dir = .prefix,
@@ -241,11 +176,10 @@ pub fn build(b: *std.Build) anyerror!void {
     const docs_step = b.step("docs", "Install documentation");
     docs_step.dependOn(&install_docs.step);
 
-    const user_step = try arch.configure_user(b, user);
-    const kernel_step = try arch.configure_kernel(b, kernel, user_step);
+    const kernel_step = try arch.add_target_specific(b, kernel);
 
     // TODO QEMU binary override
-    const qemu_info = switch (kernel_target.result.cpu.arch) {
+    const qemu_info = switch (target.result.cpu.arch) {
         .riscv64 => .{ "qemu-system-riscv64", "rv64" },
         .aarch64 => .{ "qemu-system-aarch64", "cortex-a72" },
         else => unreachable,
@@ -267,7 +201,7 @@ pub fn build(b: *std.Build) anyerror!void {
         "none",
     });
 
-    if (kernel_target.result.cpu.arch == .riscv64) {
+    if (target.result.cpu.arch == .riscv64) {
         qemu_cmd.addArgs(&.{ "-bios", "etc/boot/rv64_fw_jump.bin" });
     }
 

etc/riscv64-unknown-none.ld

@@ -23,8 +23,6 @@ SECTIONS {
 
     .tdata : ALIGN(4K) {
         PROVIDE(__tdata_start = .);
-        /* Storage for thread-locals used in assembly */
-        KEEP(*(.tdata.assembly*));
         *(.tdata*)
         PROVIDE(__tdata_end = .);
     }

src/arch.zig

@@ -4,33 +4,10 @@
 const std = @import("std");
 const builtin = @import("builtin");
 
-pub const cpu: enum {
-    riscv64,
-    aarch64,
-} = switch (builtin.cpu.arch) {
-    .riscv64 => .riscv64,
-    .aarch64 => .aarch64,
-    else => @compileError("Unsupported architecture"),
-};
-
-pub const impl = switch (cpu) {
+pub const impl = switch (builtin.cpu.arch) {
     .riscv64 => @import("arch/riscv64.zig"),
     .aarch64 => @import("arch/aarch64.zig"),
-};
-
-pub const vmm = impl.vmm;
-
-pub const IrqGuard = struct {
-    state: bool,
-
-    pub fn acquire() @This() {
-        const state = set_interrupt_mask(true);
-        return .{ .state = state };
-    }
-
-    pub fn release(self: @This()) void {
-        set_interrupt_mask(self.state);
-    }
+    else => @compileError("Unsupported architecture"),
 };
 
 /// Halts the CPU execution indefinitely, without ever returning.

src/arch/aarch64.zig

@@ -3,8 +3,6 @@ const std = @import("std");
 const boot = @import("aarch64/boot.zig");
 const regs = @import("aarch64/regs.zig");
 
-pub const vmm = @import("aarch64/vmm.zig");
-
 export const _ = boot.aa64_bsp_lower_entry;
 
 pub const Context = @import("aarch64/context.zig").Context;

src/arch/aarch64/boot.zig

@@ -13,10 +13,8 @@ extern const __aa64_bsp_stack_top: u8;
 
 var g_dtb_address: u64 = undefined;
 
-fn early_debug_print_high(byte: u8) void {
-    // TODO this is incorrect: writes should come to a memory region marked as device memory,
-    //      "virtualize" range is normal memory.
-    const address = 0x9000000 + vmm.VIRTUALIZE_BASE;
+fn early_debug_print(byte: u8) void {
+    const address = 0x9000000;
     @as(*volatile u32, @ptrFromInt(address)).* = byte;
 }
 
@@ -46,15 +44,14 @@ fn aa64_bsp_upper_entry(real_address: u64) callconv(.C) noreturn {
 
     arch.barrier(.acq_rel);
     aa64_relocate_kernel(rel_offset, rela_start, rela_end);
-    vmm.unmap_early();
     arch.barrier(.acq_rel);
 
-    log.set_write_fn(&early_debug_print_high);
+    log.set_write_fn(&early_debug_print);
 
     exception.init();
 
-    mem.PhysicalAddress.g_virtualize_base = vmm.VIRTUALIZE_BASE;
-    mem.PhysicalAddress.g_virtualize_size = 16 << vmm.L1.SHIFT;
+    mem.PhysicalAddress.g_virtualize_base = 0;
+    mem.PhysicalAddress.g_virtualize_size = 16 << 30;
 
     setup_memory_from_fdt(real_address);
 

src/arch/aarch64/context.S

@@ -3,7 +3,6 @@
 .global __aa64_enter_task
 .global __aa64_switch_task
 .global __aa64_task_enter_kernel
-.global __aa64_task_enter_user
 
 .set CONTEXT_SIZE, (12 * 8)
 
@@ -29,51 +28,14 @@
 
 .pushsection .text
 
-.set SPSR_ELx_I,    (1 << 9)
-.set SPSR_ELx_EL1h, (0b0101)
-
-__aa64_task_enter_user:
-    // x0 == sp, ...
-    ldr x0, [sp, #16 * 0]
-    msr sp_el0, x0
-
-    // x0 == arg, x1 == entry
-    ldp x0, x1, [sp, #16 * 1]
-    add sp, sp, #32
-
-    msr elr_el1, x1
-
-    // SPSR_ELx_M[4:0] = 0, a return to EL0, AArch64 mode
-    mov x1, #SPSR_ELx_I
-    msr spsr_el1, x1
-
-    mov lr, xzr
-
-    dsb ish
-    isb sy
-
-    eret
-
 __aa64_task_enter_kernel:
     // arg, entry
-    ldp x0, x1, [sp]
-    // return address
-    ldr lr, [sp, #16]
-    add sp, sp, #24
+    ldp x0, lr, [sp]
+    add sp, sp, #16
 
-    msr elr_el1, x1
+    // TODO enter task via eret to EL1t
 
-    // SPSR_ELx_M[4:0] = 0b100, a return to EL1t, AArch64 mode
-    mov x1, #SPSR_ELx_EL1h
-    orr x1, x1, #SPSR_ELx_I
-    msr spsr_el1, x1
-
-    mov x1, xzr
-
-    dsb ish
-    isb sy
-
-    eret
+    ret
 
 __aa64_switch_task:
     // x0 -- "dst" context

src/arch/aarch64/context.zig

@@ -1,83 +1,30 @@
 const thread = @import("../../thread.zig");
-const vmm = @import("vmm.zig");
-const mem = @import("../../mem.zig");
-const regs = @import("regs.zig");
-const kernel = @import("../../kernel.zig");
 
-const ProcessAddressSpace = mem.vmm.ProcessAddressSpace;
-const arch = kernel.arch;
+fn idle_function() callconv(.naked) noreturn {
+    asm volatile ("b .");
+}
 
 extern fn __aa64_enter_task(cx: *Context) callconv(.C) noreturn;
 extern fn __aa64_switch_task(dcx: *Context, scx: *Context) callconv(.C) void;
 extern fn __aa64_task_enter_kernel() callconv(.C) noreturn;
-extern fn __aa64_task_enter_user() callconv(.C) noreturn;
 
 pub const Context = extern struct {
     const STACK_SIZE: usize = 16384;
 
     kstack: thread.KStack(STACK_SIZE),
 
-    ttbr0: u64 = 0,
-
     pub fn idle() Context {
-        return Context.kernel(&thread.idle_function, 0);
+        const entry = @intFromPtr(&idle_function);
+        return Context.kernel(entry, 0);
     }
 
-    pub fn user(address_space: *const ProcessAddressSpace, pc: usize, sp: usize, arg: usize) @This() {
-        const space_physical = address_space.physical_address();
-        const space_asid = address_space.asid();
-
+    pub fn kernel(pc: usize, arg: usize) Context {
         var ks = thread.KStack(STACK_SIZE).create();
+        const entry = @intFromPtr(&__aa64_task_enter_kernel);
 
-        const ttbr0 = @as(u64, @bitCast(regs.TTBR0_EL1.Bits{
-            .BADDR = @truncate(space_physical.raw),
-            .ASID = @truncate(space_asid),
-        }));
-
-        // Arguments to __aa64_task_enter_user
         ks.push(pc);
         ks.push(arg);
-        ks.push(0); // Padding
-        ks.push(sp);
 
-        setup_stack_common(&ks, @intFromPtr(&__aa64_task_enter_user));
-
-        return .{ .kstack = ks, .ttbr0 = ttbr0 };
-    }
-
-    pub fn kernel(function: *const thread.KernelThreadFn, arg: usize) Context {
-        var ks = thread.KStack(STACK_SIZE).create();
-
-        // Arguments to __aa64_task_enter_kernel
-        ks.push(@intFromPtr(&thread.kernel_return));
-        ks.push(@intFromPtr(function));
-        ks.push(arg);
-
-        setup_stack_common(&ks, @intFromPtr(&__aa64_task_enter_kernel));
-
-        return Context{ .kstack = ks };
-    }
-
-    pub fn enter(self: *Context) noreturn {
-        self.load_state();
-        __aa64_enter_task(self);
-    }
-
-    pub fn switch_from(self: *Context, from: *Context) void {
-        from.store_state();
-        self.load_state();
-        __aa64_switch_task(self, from);
-    }
-
-    pub fn load_state(self: *Context) void {
-        regs.TTBR0_EL1.set(self.ttbr0);
-    }
-
-    pub fn store_state(self: *Context) void {
-        _ = self;
-    }
-
-    fn setup_stack_common(ks: *thread.KStack(STACK_SIZE), entry: usize) void {
         ks.push(entry); // x30/lr
         ks.push(0); // x29
         ks.push(0); // x28
@@ -90,6 +37,16 @@ pub const Context = extern struct {
         ks.push(0); // x21
         ks.push(0); // x20
         ks.push(0); // x19
+
+        return Context{ .kstack = ks };
+    }
+
+    pub fn enter(self: *Context) noreturn {
+        __aa64_enter_task(self);
+    }
+
+    pub fn switch_from(self: *Context, from: *Context) void {
+        __aa64_switch_task(self, from);
     }
 };
 

src/arch/aarch64/exception.zig

@@ -3,16 +3,11 @@ const kernel = @import("../../kernel.zig");
 
 const arch = kernel.arch;
 const log = kernel.debug.log;
-const syscall = kernel.syscall;
 
 extern const __aa64_exception_vectors: u8;
 
 pub const ExceptionFrame = extern struct {
     xN: [32]usize,
-    spsr_el1: usize,
-    elr_el1: usize,
-    sp_el0: usize,
-    _0: usize,
 
     pub fn dump(self: *const ExceptionFrame, comptime level: log.Level) void {
         for (0..16) |i| {
@@ -46,7 +41,6 @@ export fn __aa64_el1_sync_handler(frame: *ExceptionFrame) callconv(.C) void {
 
     log.err("Exception in EL1:", .{});
     log.err("  EC = {s} (0b{b:06}) ISS = 0x{x}", .{ esr.EC.as_str(), @intFromEnum(esr.EC), esr.ISS });
-    log.err("  ESR = 0x{x:016}", .{@as(u64, @bitCast(esr))});
     log.err("  ELR = 0x{x:016}", .{elr});
 
     switch (esr.as_enum()) {
@@ -88,21 +82,8 @@ export fn __aa64_el1_serror_handler(frame: *ExceptionFrame) callconv(.C) void {
 
 // EL0
 export fn __aa64_el0_sync_handler(frame: *ExceptionFrame) callconv(.C) void {
-    const esr = regs.ESR_EL1.read();
-
-    switch (esr.as_enum()) {
-        .svc => {
-            syscall.syscall_handler(frame.xN[8], frame.xN[0..6]);
-            return;
-        },
-        else => {},
-    }
-
-    log.err("Unhandled exception in EL0:", .{});
-    log.err("  EC = {s} (0b{b:06}) ISS = 0x{x}", .{ esr.EC.as_str(), @intFromEnum(esr.EC), esr.ISS });
-    log.err("  ESR = 0x{x:016}", .{@as(u64, @bitCast(esr))});
-    log.err("  ELR = 0x{x:016}", .{frame.elr_el1});
-    frame.dump(log.Level.err);
+    // TODO EL0
+    _ = frame;
     arch.halt();
 }
 
@@ -112,12 +93,14 @@ export fn __aa64_el0_irq_handler(frame: *ExceptionFrame) callconv(.C) void {
 
 export fn __aa64_el0_fiq_handler(frame: *ExceptionFrame) callconv(.C) void {
     _ = frame;
-    @panic("__aa64_el0_fiq_handler");
+    // TODO I've never used FIQ
+    arch.halt();
 }
 
 export fn __aa64_el0_serror_handler(frame: *ExceptionFrame) callconv(.C) void {
     _ = frame;
-    @panic("__aa64_el0_serror_handler");
+    // TODO
+    arch.halt();
 }
 
 comptime {

src/arch/aarch64/regs.zig

@@ -6,8 +6,6 @@ fn Register(comptime name: []const u8, comptime bits: type) type {
         else => bits,
     };
     return enum(repr) {
-        pub const Bits = bits;
-
         pub fn set(value: repr) void {
             asm volatile ("msr " ++ name ++ ", %[value]"
                 :
@@ -36,15 +34,8 @@ fn Register(comptime name: []const u8, comptime bits: type) type {
     };
 }
 
-pub const TTBR = packed struct(u64) {
-    // 0..48
-    BADDR: u48 = 0,
-    // 48..64
-    ASID: u16 = 0,
-};
-
-pub const TTBR0_EL1 = Register("ttbr0_el1", TTBR);
-pub const TTBR1_EL1 = Register("ttbr1_el1", TTBR);
+pub const TTBR0_EL1 = Register("ttbr0_el1", u64);
+pub const TTBR1_EL1 = Register("ttbr1_el1", u64);
 
 // NOTE: tpidr_el0 is used until codegen can emit TLS instructions against tpidr_el1
 pub const TPIDR_EL0 = Register("tpidr_el0", u64);
@@ -76,7 +67,6 @@ pub const ESR_EL1 = Register("esr_el1", packed struct(u64) {
     // 26..32
     EC: enum(u6) {
         unknown = 0b000000,
-        svc = 0b010101,
         data_abort_lower_el = 0b100100,
         data_abort_same_el = 0b100101,
         sp_align = 0b100110,
@@ -146,16 +136,14 @@ pub const ESR_EL1 = Register("esr_el1", packed struct(u64) {
 
     pub const AsEnum = union(enum) {
         data_abort: DataAbort,
-        svc,
         other,
     };
 
     pub fn as_enum(self: @This()) AsEnum {
-        return switch (self.EC) {
-            .data_abort_lower_el, .data_abort_same_el => .{ .data_abort = @bitCast(self.ISS) },
-            .svc => .svc,
-            else => .other,
-        };
+        switch (self.EC) {
+            .data_abort_lower_el, .data_abort_same_el => return .{ .data_abort = @bitCast(self.ISS) },
+            else => return .other,
+        }
     }
 });
 

src/arch/aarch64/vectors.S

@@ -2,14 +2,11 @@
 
 // 32 general-purpose registers
 .set EXC_GP_SIZE, (32 * 8)
-// 4 special-purpose registers
-.set EXC_SP_SIZE, (4 * 8)
-.set EXC_STATE_SIZE, (EXC_GP_SIZE + EXC_SP_SIZE)
+.set EXC_STATE_SIZE, (EXC_GP_SIZE)
 
 .macro EXC_SAVE_STATE
     sub sp, sp, #EXC_STATE_SIZE
 
-    // General-purpose block
     stp  x0,  x1, [sp, #16 *  0]
     stp  x2,  x3, [sp, #16 *  1]
     stp  x4,  x5, [sp, #16 *  2]
@@ -26,45 +23,6 @@
     stp x26, x27, [sp, #16 * 13]
     stp x28, x29, [sp, #16 * 14]
     stp x30, x31, [sp, #16 * 15]
-
-    // Special-purpose block
-    mrs x0, spsr_el1
-    mrs x1, elr_el1
-    mrs x2, sp_el0
-    mov x3, xzr     // Padding
-
-    stp x0, x1, [sp, #EXC_GP_SIZE + 16 * 0]
-    stp x2, x3, [sp, #EXC_GP_SIZE + 16 * 1]
-.endm
-
-.macro EXC_RESTORE_STATE
-    // Special-purpose block
-    ldp x0, x1, [sp, #EXC_GP_SIZE + 16 * 0]
-    ldp x2, x3, [sp, #EXC_GP_SIZE + 16 * 1]
-
-    msr spsr_el1, x0
-    msr elr_el1, x1
-    msr sp_el0, x2
-
-    // General-purpose block
-    ldp  x0,  x1, [sp, #16 *  0]
-    ldp  x2,  x3, [sp, #16 *  1]
-    ldp  x4,  x5, [sp, #16 *  2]
-    ldp  x6,  x7, [sp, #16 *  3]
-    ldp  x8,  x9, [sp, #16 *  4]
-    ldp x10, x11, [sp, #16 *  5]
-    ldp x12, x13, [sp, #16 *  6]
-    ldp x14, x15, [sp, #16 *  7]
-    ldp x16, x17, [sp, #16 *  8]
-    ldp x18, x19, [sp, #16 *  9]
-    ldp x20, x21, [sp, #16 * 10]
-    ldp x22, x23, [sp, #16 * 11]
-    ldp x24, x25, [sp, #16 * 12]
-    ldp x26, x27, [sp, #16 * 13]
-    ldp x28, x29, [sp, #16 * 14]
-    ldp x30, x31, [sp, #16 * 15]
-
-    add sp, sp, #EXC_STATE_SIZE
 .endm
 
 // Exception vector size is 0x80
@@ -80,22 +38,13 @@ __aa\bits\()_el\el\ht\()_\kind:
     // TODO taking exceptions from EL0t 32-bit
     b .
 .endif
+
     EXC_SAVE_STATE
-
-    dsb ish
-    isb sy
-
     mov x0, sp
     mov lr, xzr
     bl __aa64_el\el\()_\kind\()_handler
-
-    EXC_RESTORE_STATE
-
-    ic iallu
-    dsb ishst
-    isb sy
-
-    eret
+    // TODO exception return
+    b .
 .size __aa\bits\()_el\el\ht\()_\kind, . - __aa\bits\()_el\el\ht\()_\kind
 .endm
 

src/arch/aarch64/vmm.zig

@@ -1,21 +1,14 @@
-const std = @import("std");
 const mem = @import("../../mem.zig");
 const regs = @import("regs.zig");
-const kernel = @import("../../kernel.zig");
 
 const PhysicalAddress = mem.PhysicalAddress;
-const AtomicU8 = std.atomic.Value(u8);
-const log = kernel.log;
 
 pub const KERNEL_VIRTUAL_BASE: usize = 0xFFFFFF8000000000;
 pub const KERNEL_L1_INDEX: usize = L1.index(KERNEL_VIRTUAL_BASE);
-pub const KERNEL_VIRTUAL_SIZE: usize = 16 * L1.SIZE;
-pub const VIRTUALIZE_BASE: usize = KERNEL_VIRTUAL_BASE + KERNEL_VIRTUAL_SIZE;
-pub const VIRTUALIZE_BASE_L1I: usize = L1.index(VIRTUALIZE_BASE);
 
-pub const L1 = mem.TranslationLevel(30, L2);
-pub const L2 = mem.TranslationLevel(21, L3);
-pub const L3 = mem.vmm.L3;
+pub const L1 = mem.TranslationLevel(30);
+pub const L2 = mem.TranslationLevel(21);
+pub const L3 = mem.TranslationLevel(12);
 
 pub const RawEntry = packed struct(u64) {
     // 0
@@ -142,153 +135,31 @@ pub fn Table(comptime Level: type) type {
     return struct {
         pub const Entry = TableEntry(Level);
 
-        pub const Error = mem.vmm.AddressSpaceError;
-
         entries: [512]Entry align(4096) = [_]Entry{.INVALID} ** 512,
 
-        pub fn allocate_empty() Error!*@This() {
-            const page = mem.phys.alloc_page() orelse return error.out_of_pages;
-            const table = @as(*@This(), @ptrFromInt(page.virtualize()));
-            for (0..512) |i| {
-                table.entry(i).* = .INVALID;
-            }
-            return table;
-        }
-
-        pub fn from_physical_address(physical: PhysicalAddress) *@This() {
-            return @ptrFromInt(physical.virtualize());
-        }
-
         pub inline fn entry(self: *@This(), index: usize) *Entry {
             return &self.entries[index];
         }
-
-        pub fn physical_address(self: *const @This()) PhysicalAddress {
-            return PhysicalAddress.from_virtualized(@intFromPtr(self));
-        }
-
-        pub usingnamespace if (Level.NextLevel) |NextLevel| struct {
-            pub fn get_next_level(self: *Table(Level), index: usize) ?*Table(NextLevel) {
-                const ent = self.entry(index);
-                if (ent.raw.V and !ent.raw.P) {
-                    return Table(NextLevel).from_physical_address(ent.address());
-                }
-                return null;
-            }
-
-            pub fn get_or_create_next_level(self: *Table(Level), index: usize) Error!*Table(NextLevel) {
-                const ent = self.entry(index);
-                if (ent.raw.V) {
-                    if (!ent.raw.P) {
-                        @panic("TODO: mixed hugepages and tables");
-                    }
-
-                    // Entry is a table
-                    return Table(NextLevel).from_physical_address(ent.address());
-                } else {
-                    const table = try Table(NextLevel).allocate_empty();
-                    const physical = table.physical_address();
-                    ent.* = TableEntry(Level).table(physical, .{});
-                    return table;
-                }
-            }
-        } else struct {};
     };
 }
 
-pub const ProcessAddressSpace = struct {
-    l1: *Table(L1),
-    asid: u8,
-
-    pub const Error = mem.vmm.AddressSpaceError;
-
-    var g_asid: AtomicU8 = .{ .raw = 1 };
-
-    pub fn init() Error!ProcessAddressSpace {
-        const table = try Table(L1).allocate_empty();
-        const asid = g_asid.fetchAdd(1, .seq_cst);
-        return .{ .l1 = table, .asid = asid };
-    }
-
-    pub fn physical_address(self: *const @This()) PhysicalAddress {
-        return self.l1.physical_address();
-    }
-
-    pub fn map_page(self: *@This(), virtual: usize, physical: PhysicalAddress) Error!void {
-        // TODO align check on both virtual and physical
-
-        const l1i = L1.index(virtual);
-        const l2i = L2.index(virtual);
-        const l3i = L3.index(virtual);
-
-        const l2 = try self.l1.get_or_create_next_level(l1i);
-        const l3 = try l2.get_or_create_next_level(l2i);
-
-        const entry = l3.entry(l3i);
-
-        if (entry.raw.V) {
-            @panic("TODO: handle already present");
-        }
-
-        entry.* = TableEntry(L3).normal_page(physical, RawEntry{ .AP = .both_readwrite, .NG = true });
-        tlb_flush_vma_asid(virtual, self.asid);
-
-        log.debug("Map 0x{x} -> page 0x{x}", .{ virtual, physical.raw });
-    }
-};
-
-pub inline fn tlb_flush_vma(vma: usize) void {
-    const xt = vma >> 12;
-    asm volatile (
-        \\ dsb ishst
-        \\ tlbi vaae1, %[xt]
-        \\ dsb ish
-        \\ isb sy
-        :
-        : [xt] "r" (xt),
-        : "memory"
-    );
-}
-
-pub inline fn tlb_flush_vma_asid(vma: usize, asid: usize) void {
-    const xt = (vma >> 12) | (asid << 48);
-    asm volatile (
-        \\ dsb ishst
-        \\ tlbi vae1, %[xt]
-        \\ dsb ish
-        \\ isb sy
-        :
-        : [xt] "r" (xt),
-        : "memory"
-    );
-}
-
-pub inline fn tlb_flush_asid(asid: usize) void {
-    const xt = asid << 48;
-    asm volatile (
-        \\ dsb ishst
-        \\ tlbi aside1, %[xt]
-        \\ dsb ish
-        \\ isb sy
-        :
-        : [xt] "r" (xt),
-        : "memory"
-    );
-}
-
+// 0x0000_0000_0000_0000 .. 0x0000_0080_0000_0000
+var g_fixed_low = Table(L1){};
 // 0xFFFF_FF80_0000_0000 .. 0xFFFF_FFFF_FFFF_FFFF
 var g_fixed_high = Table(L1){};
 
-pub fn unmap_early() void {
-    // Flush whole ASID 0
-    tlb_flush_asid(0);
-    regs.TTBR0_EL1.set(0);
-}
-
 pub fn map_early(real_address: usize) void {
     _ = real_address;
 
-    for (0..L1.page_count(KERNEL_VIRTUAL_SIZE)) |i| {
+    for (0..16) |i| {
+        // Identity
+        g_fixed_low.entry(i).* = TableEntry(L1).normal_block(
+            .{ .raw = i << L1.SHIFT },
+            .{},
+        );
+    }
+
+    for (0..16) |i| {
         // Identity + KERNEL_VIRTUAL_BASE
         g_fixed_high.entry(i).* = TableEntry(L1).normal_block(
             .{ .raw = i << L1.SHIFT },
@@ -296,18 +167,11 @@ pub fn map_early(real_address: usize) void {
         );
     }
 
-    for (0..16) |i| {
-        // Identity + VIRTUALIZE_BASE for "Whole RAM mapping"
-        g_fixed_high.entry(VIRTUALIZE_BASE_L1I + i).* = TableEntry(L1).normal_block(
-            .{ .raw = i << L1.SHIFT },
-            .{},
-        );
-    }
+    const ttbr0 = @intFromPtr(&g_fixed_low);
+    const ttbr1 = @intFromPtr(&g_fixed_high);
 
-    const ttbr = @intFromPtr(&g_fixed_high);
-
-    regs.TTBR0_EL1.write(.{ .BADDR = @truncate(ttbr) });
-    regs.TTBR1_EL1.write(.{ .BADDR = @truncate(ttbr) });
+    regs.TTBR0_EL1.set(ttbr0);
+    regs.TTBR1_EL1.set(ttbr1);
 
     regs.TCR_EL1.write(.{
         .AS = .asid_8bit,

src/arch/riscv64.zig

@@ -5,19 +5,11 @@ const regs = @import("riscv64/regs.zig");
 const std = @import("std");
 const builtin = @import("builtin");
 
-pub const vmm = @import("riscv64/vmm.zig");
-
 export const _ = boot.rv64_bsp_lower_entry;
 
 /// This CPU's HART (HARdware Thread) ID.
 pub threadlocal var t_hart_id: u32 = 0;
 
-// Linked as .tdata.assembly to ensure `tp == &this`
-pub export threadlocal var t_tdata_assembly: extern struct {
-    kernel_stack_pointer: usize, // tp + 0x00
-    user_stack_pointer: usize, // tp + 0x08
-} linksection(".tdata.assembly") = undefined;
-
 /// RISC-V task context
 pub const Context = @import("riscv64/context.zig").Context;
 

src/arch/riscv64/boot.zig

@@ -37,12 +37,9 @@ fn bsp_upper_entry(real_address: usize, unused: usize) callconv(.C) noreturn {
     exception.init();
 
     debug.log.set_write_fn(&sbi.debug_print_byte);
-    kernel.mem.PhysicalAddress.g_virtualize_base = vmm.VIRTUALIZE_BASE;
+    kernel.mem.PhysicalAddress.g_virtualize_base = 0;
     kernel.mem.PhysicalAddress.g_virtualize_size = vmm.virtualize_range();
 
-    // Enable supervisor access to user memory
-    regs.SSTATUS.modify(.{ .SUM = true }, .{});
-
     // Setup physical memory management
     setup_memory_from_fdt(real_address);
 
@@ -58,8 +55,6 @@ pub export fn rv64_bsp_lower_entry(real_address: usize, bsp_hart_id: usize, dtb_
     g_dtb_address = dtb_address;
     g_bsp_hart_id = @truncate(bsp_hart_id);
 
-    vmm.g_kernel_real_base = real_address;
-
     vmm.map_early(real_address);
 
     // &bspUpperEntry will yield a pointer like: X + P, where

src/arch/riscv64/context.S

@@ -4,7 +4,6 @@
 
 .global __rv64_enter_task
 .global __rv64_switch_task
-.global __rv64_task_enter_user
 .global __rv64_task_enter_kernel
 
 .macro LOAD_TASK_STATE
@@ -45,48 +44,13 @@
     sd s0,  13 * 8(sp)
 .endm
 
-.set SSTATUS_SPP, (1 << 8)
-.set SSTATUS_SPIE, (1 << 5)
-
-__rv64_task_enter_user:
-    csrw sscratch, tp
-    // TODO setup user thread pointer
-
-    ld a0, (sp)     // argument
-    ld ra, 16(sp)   // entry
-    ld sp, 8(sp)    // stack
-
-    mv tp, zero
-
-    // Clear SPP to zero to indicate a return to U-mode
-    li t1, SSTATUS_SPP
-    not t1, t1
-
-    csrr t0, sstatus
-    // TODO enable interrupts via SPIE
-    // ori t0, t0, SSTATUS_SPIE
-    and t0, t0, t1
-    csrw sstatus, t0
-    csrw sepc, ra
-
-    sret
-
 __rv64_task_enter_kernel:
     ld a0, (sp)     // argument
-    ld t0, 8(sp)    // entry
-    ld ra, 16(sp)   // return address
-    addi sp, sp, 24
+    ld ra, 8(sp)    // entry
+    addi sp, sp, 16
 
-    // Set SPP to indicate a return to S-mode
-    csrr t1, sstatus
-    // TODO enable interrupts via SPIE
-    // ori t0, t0, SSTATUS_SPIE
-    ori t1, t1, SSTATUS_SPP
-    csrw sstatus, t1
-    csrw sepc, t0
-    csrw sscratch, zero
-
-    sret
+    // TODO S-mode -> S-mode return via sret
+    ret
 
 __rv64_switch_task:
     // a0 - new context

src/arch/riscv64/context.zig

@@ -1,17 +1,12 @@
 const thread = @import("../../thread.zig");
-const mem = @import("../../mem.zig");
-const kernel = @import("../../kernel.zig");
-const regs = @import("regs.zig");
-const vmm = @import("vmm.zig");
-const riscv64 = @import("../riscv64.zig");
 
-const ProcessAddressSpace = mem.vmm.ProcessAddressSpace;
-const log = kernel.log;
+fn idle_function() callconv(.naked) noreturn {
+    asm volatile ("j .");
+}
 
 extern fn __rv64_enter_task(cx: *Context) callconv(.C) noreturn;
 extern fn __rv64_switch_task(dcx: *Context, scx: *Context) callconv(.C) void;
 extern fn __rv64_task_enter_kernel() callconv(.C) noreturn;
-extern fn __rv64_task_enter_user() callconv(.C) noreturn;
 
 pub const Context = extern struct {
     const STACK_SIZE: usize = 8192;
@@ -19,69 +14,20 @@ pub const Context = extern struct {
     // Has to be exactly at offset 0x00, used in assembly.
     kstack: thread.KStack(STACK_SIZE),
 
-    satp: u64 = 0,
-
     /// Constructs an idle context struct.
     pub fn idle() @This() {
-        return Context.kernel(&thread.idle_function, 0);
-    }
-
-    pub fn user(address_space: *const ProcessAddressSpace, pc: usize, sp: usize, arg: usize) @This() {
-        const space_physical = address_space.physical_address();
-        const space_asid = address_space.asid();
-
-        const satp = regs.SATP.Bits{ .PPN = @truncate(space_physical.raw >> 12), .ASID = @truncate(space_asid), .MODE = .sv39 };
-
-        var ks = thread.KStack(STACK_SIZE).create();
-
-        ks.push(pc);
-        ks.push(sp);
-        ks.push(arg);
-
-        setup_stack_common(&ks, @intFromPtr(&__rv64_task_enter_user));
-
-        return .{ .kstack = ks, .satp = @bitCast(satp) };
+        const entry = @intFromPtr(&idle_function);
+        return Context.kernel(entry, 0);
     }
 
     /// Constructs a kernel task context with entry point in `pc` and an `arg`ument.
-    pub fn kernel(function: *const thread.KernelThreadFn, arg: usize) @This() {
+    pub fn kernel(pc: usize, arg: usize) @This() {
         var ks = thread.KStack(STACK_SIZE).create();
+        const entry = @intFromPtr(&__rv64_task_enter_kernel);
 
-        const table_physical = vmm.kernel_table_physical();
-        const satp = regs.SATP.Bits{ .PPN = @truncate(table_physical >> 12), .MODE = .sv39 };
-
-        ks.push(@intFromPtr(&thread.kernel_return));
-        ks.push(@intFromPtr(function));
+        ks.push(pc);
         ks.push(arg);
 
-        setup_stack_common(&ks, @intFromPtr(&__rv64_task_enter_kernel));
-
-        return .{ .kstack = ks, .satp = @bitCast(satp) };
-    }
-
-    /// Low-level task context entry function.
-    pub fn enter(self: *@This()) noreturn {
-        self.load_state();
-        __rv64_enter_task(self);
-    }
-
-    /// Low-level task context switch function.
-    pub fn switch_from(self: *@This(), from: *@This()) void {
-        from.store_state();
-        self.load_state();
-        __rv64_switch_task(self, from);
-    }
-
-    fn load_state(self: *@This()) void {
-        riscv64.t_tdata_assembly.kernel_stack_pointer = @intFromPtr(self.kstack.sp);
-        regs.SATP.set(self.satp);
-    }
-
-    fn store_state(self: *@This()) void {
-        _ = self;
-    }
-
-    fn setup_stack_common(ks: *thread.KStack(STACK_SIZE), entry: usize) void {
         ks.push(0); // x8/s0/fp
         ks.push(0); // x9/s1
         ks.push(0); // x18/s2
@@ -96,6 +42,18 @@ pub const Context = extern struct {
         ks.push(0); // x27/s11
         ks.push(0); // x4/gp
         ks.push(entry); // x1/ra return address
+
+        return .{ .kstack = ks };
+    }
+
+    /// Low-level task context entry function.
+    pub fn enter(self: *@This()) noreturn {
+        __rv64_enter_task(self);
+    }
+
+    /// Low-level task context switch function.
+    pub fn switch_from(self: *@This(), from: *@This()) void {
+        __rv64_switch_task(self, from);
     }
 };
 

src/arch/riscv64/exception.zig

@@ -1,9 +1,8 @@
 const regs = @import("regs.zig");
-const kernel = @import("../../kernel.zig");
+const debug = @import("../../debug.zig");
+const arch = @import("../../kernel.zig").arch;
 
-const syscall = kernel.syscall;
-const arch = kernel.arch;
-const log = kernel.log;
+const log = debug.log;
 
 extern fn __rv64_exception_vectors() void;
 
@@ -52,13 +51,6 @@ pub const ExceptionFrame = extern struct {
     sN: [12]usize,
     aN: [8]usize,
 
-    umode_sp: usize,
-    sstatus: usize,
-    sepc: usize,
-    stval: usize,
-    scause: usize,
-    sscratch: usize,
-
     pub fn dump(self: *const @This(), comptime level: log.Level) void {
         log.writeln(level, " ra = 0x{x:016}   gp = 0x{x:016}", .{ self.ra, self.gp });
         log.writeln(level, " t0 = 0x{x:016}   t1 = 0x{x:016}", .{ self.tN[0], self.tN[1] });
@@ -86,38 +78,17 @@ pub fn init() void {
 }
 
 export fn rv64SmodeTrapGeneral(frame: *ExceptionFrame) callconv(.C) void {
-    // const scause = regs.SCAUSE.read();
-    const scause = @as(regs.SCAUSE.Bits, @bitCast(frame.scause));
+    const scause = regs.SCAUSE.read();
     if (scause.INTERRUPT) {
         return rv64SmodeTrapInterrupt(frame);
     }
-    const sstatus = @as(regs.SSTATUS.Bits, @bitCast(frame.sstatus));
     const cause = @as(ExceptionCause, @enumFromInt(scause.CODE));
+    const epc = regs.SEPC.get();
+    const tval = regs.STVAL.get();
 
-    const is_umode = !sstatus.SPP;
-
-    switch (cause) {
-        .ecall_umode => {
-            // TODO assert that `is_umode`
-            const func = frame.aN[0];
-            const args = frame.aN[1..7];
-            const result = syscall.syscall_handler(func, args);
-            frame.aN[0] = result;
-
-            // Add size of `ecall` instruction to return epc to execute the next instruction
-            // instead of falling back to the same `ecall` instruction that caused this
-            // interrupt.
-            frame.sepc += 4;
-            return;
-        },
-        else => {},
-    }
-
-    const mode_str = if (is_umode) "U-mode" else "S-mode";
-
-    log.err("{s} exception:", .{mode_str});
+    log.err("S-mode exception:", .{});
     log.err("  Cause: {s} (0x{x})", .{ cause.name(), scause.CODE });
-    log.err("  stval = 0x{x:016}  sepc = 0x{x:016}", .{ frame.stval, frame.sepc });
+    log.err("  stval = 0x{x:016}  sepc = 0x{x:016}", .{ tval, epc });
     frame.dump(.err);
 
     @panic("Unhandled exception in S-mode");

src/arch/riscv64/regs.zig

@@ -4,8 +4,6 @@ fn Register(comptime name: []const u8, comptime bits: type) type {
         else => bits,
     };
     return enum(repr) {
-        pub const Bits = bits;
-
         pub fn set(value: repr) void {
             asm volatile ("csrw " ++ name ++ ", %[value]"
                 :

src/arch/riscv64/vectors.S

@@ -3,17 +3,8 @@
 .extern rv64SmodeTrapInterrupt
 
 // ra, gp, 7×tN, 12×sN, 8×aN
-.set GP_REGS_SIZE,      ((2 + 7 + 12 + 8) * 8)
-// U-mode sp, sstatus, sepc, stval, scause, sscratch
-.set SP_REGS_SIZE,      (6 * 8)
-.set TRAP_CONTEXT_SIZE, (GP_REGS_SIZE + SP_REGS_SIZE)
-
-.set REG_UMODE_SP,      (GP_REGS_SIZE + 0 * 8)
-.set REG_SSTATUS,       (GP_REGS_SIZE + 1 * 8)
-.set REG_SEPC,          (GP_REGS_SIZE + 2 * 8)
-.set REG_STVAL,         (GP_REGS_SIZE + 3 * 8)
-.set REG_SCAUSE,        (GP_REGS_SIZE + 4 * 8)
-.set REG_SSCRATCH,      (GP_REGS_SIZE + 5 * 8)
+.set GP_REGS_SIZE,      (2 + 7 + 12 + 8) * 8
+.set TRAP_CONTEXT_SIZE, (GP_REGS_SIZE)
 
 .macro SAVE_GP_REGS
     sd ra,   0 * 8(sp)
@@ -50,110 +41,19 @@
     sd a7,  28 * 8(sp)
 .endm
 
-.macro RESTORE_GP_REGS
-    ld ra,   0 * 8(sp)
-    ld gp,   1 * 8(sp)
-
-    ld t0,   2 * 8(sp)
-    ld t1,   3 * 8(sp)
-    ld t2,   4 * 8(sp)
-    ld t3,   5 * 8(sp)
-    ld t4,   6 * 8(sp)
-    ld t5,   7 * 8(sp)
-    ld t6,   8 * 8(sp)
-
-    ld s0,   9 * 8(sp)
-    ld s1,  10 * 8(sp)
-    ld s2,  11 * 8(sp)
-    ld s3,  12 * 8(sp)
-    ld s4,  13 * 8(sp)
-    ld s5,  14 * 8(sp)
-    ld s6,  15 * 8(sp)
-    ld s7,  16 * 8(sp)
-    ld s8,  17 * 8(sp)
-    ld s9,  18 * 8(sp)
-    ld s10, 19 * 8(sp)
-    ld s11, 20 * 8(sp)
-
-    ld a0,  21 * 8(sp)
-    ld a1,  22 * 8(sp)
-    ld a2,  23 * 8(sp)
-    ld a3,  24 * 8(sp)
-    ld a4,  25 * 8(sp)
-    ld a5,  26 * 8(sp)
-    ld a6,  27 * 8(sp)
-    ld a7,  28 * 8(sp)
-.endm
-
-.set TPREL_KERNEL_STACK,    (0 * 8)
-.set TPREL_USER_STACK,      (1 * 8)
-
-.set SSTATUS_SPP,           (1 << 8)
-
 .macro SMODE_TRAP n, handler
 .type __rv64_smode_trap_\n, @function
 __rv64_smode_trap_\n:
-    // If coming from U-mode, sscratch = kernel-mode tp
-    // If coming from S-mode, sscratch = 0
-    csrrw tp, sscratch, tp
-    bnez tp, 1f
-    // Coming from S-mode
-    sd sp, TPREL_KERNEL_STACK(tp)   // tdata_assembly.kernel_stack = sp
-    // [fallthrough]
-1:
-    // Coming from U-mode
-    sd sp, TPREL_USER_STACK(tp)     // tdata_assembly.user_stack = sp
-    ld sp, TPREL_KERNEL_STACK(tp)   // sp = tdata_assembly.kernel_stack
-
-    // Store pre-trap context
+    // TODO properly handle traps coming from U-mode
+    // TODO save CSRs
     addi sp, sp, -(TRAP_CONTEXT_SIZE)
-
     SAVE_GP_REGS
-    // Save special-purpose registers
-    ld t0, TPREL_USER_STACK(tp)
-    csrr t1, sstatus
-    csrr t2, sepc
-    csrr t3, stval
-    csrr t4, scause
-    csrr t5, sscratch
-
-    sd t0, REG_UMODE_SP (sp)
-    sd t1, REG_SSTATUS  (sp)
-    sd t2, REG_SEPC     (sp)
-    sd t3, REG_STVAL    (sp)
-    sd t4, REG_SCAUSE   (sp)
-    sd t5, REG_SSCRATCH (sp)
-
-    // Reset sscratch to zero to make sure a nested S-mode -> S-mode exception
-    // happens properly
-    csrw sscratch, zero
-
     mv a0, sp
+
     call \handler
 
-    // Return from exception
-    ld t0, REG_SSTATUS  (sp)
-    andi t0, t0, SSTATUS_SPP
-    bnez t0, 2f
-
-    // sstatus.SPP == 0, return to U-mode
-    // Restore sscratch to its proper value
-    csrw sscratch, tp
-    // [fallthrough]
-2:
-    // sstatus.SPP == 1, return to S-mode
-    ld t0, REG_SSTATUS  (sp)
-    ld t1, REG_SEPC     (sp)
-    csrw sstatus, t0
-    csrw sepc, t1
-
-    // Restore general-purpose registers
-    RESTORE_GP_REGS
-
-    ld tp, REG_SSCRATCH (sp)
-    ld sp, REG_UMODE_SP (sp)
-
-    sret
+    // TODO return from exception
+    j .
 .size __rv64_smode_trap_\n, . - __rv64_smode_trap_\n
 .endm
 

src/arch/riscv64/vmm.zig

@@ -1,24 +1,18 @@
-const std = @import("std");
 const sync = @import("../../sync.zig");
 const regs = @import("regs.zig");
 const mem = @import("../../mem.zig");
-const kernel = @import("../../kernel.zig");
+const arch = @import("../../kernel.zig").arch;
 
-const log = kernel.log;
-const arch = kernel.arch;
 const PhysicalAddress = mem.PhysicalAddress;
-const AtomicU8 = std.atomic.Value(u8);
 
 pub const KERNEL_VIRTUAL_BASE: usize = 0xFFFFFFF000000000;
 pub const KERNEL_VIRTUAL_L1I: usize = (KERNEL_VIRTUAL_BASE >> L1.SHIFT) & 511;
-pub const VIRTUALIZE_BASE: usize = KERNEL_VIRTUAL_BASE + L1.SIZE;
-pub const VIRTUALIZE_BASE_L1I: usize = L1.index(VIRTUALIZE_BASE);
 // 16 GiB
 const EARLY_MAPPING_SIZE: usize = 16;
 
-pub const L1 = mem.TranslationLevel(30, L2);
-pub const L2 = mem.TranslationLevel(21, L3);
-pub const L3 = mem.vmm.L3;
+pub const L1 = mem.TranslationLevel(30);
+pub const L2 = mem.TranslationLevel(21);
+pub const L3 = mem.TranslationLevel(12);
 
 pub const RawEntry = packed struct(u64) {
     // 0: Valid
@@ -51,19 +45,15 @@ pub const RawEntry = packed struct(u64) {
     }
 
     pub fn clear(self: *@This(), mask: @This()) void {
-        const lhs = @as(*u64, @ptrCast(self));
+        const lhs = @as(*u64, @bitCast(self));
         const rhs = @as(u64, @bitCast(mask));
         lhs.* &= ~rhs;
     }
-
-    pub fn is_table(self: @This()) bool {
-        return !self.r and !self.w and !self.x;
-    }
 };
 
 pub fn TableEntry(comptime Level: type) type {
     _ = Level;
-    return packed struct(u64) {
+    return struct {
         raw: RawEntry,
 
         pub const INVALID: @This() = .{ .raw = .{} };
@@ -93,9 +83,8 @@ pub fn TableEntry(comptime Level: type) type {
         }
 
         pub fn table(addr: PhysicalAddress, flags: RawEntry) @This() {
-            var f = flags;
-            f.clear(.{ .r = true, .w = true, .x = true });
-            return .{ .raw = f.make_union(.{
+            flags.clear(.{ .r = true, .w = true, .x = true });
+            return .{ .raw = flags.make_union(.{
                 .address = @as(u39, @intCast(addr.raw >> 12)),
                 .v = true,
             }) };
@@ -104,140 +93,37 @@ pub fn TableEntry(comptime Level: type) type {
 }
 
 pub fn Table(comptime Level: type) type {
-    return extern struct {
+    return struct {
         pub const Entry = TableEntry(Level);
 
         entries: [512]Entry align(4096),
 
-        pub const Error = mem.vmm.AddressSpaceError;
-
         pub fn empty() @This() {
             return .{ .entries = [_]Entry{.INVALID} ** 512 };
         }
 
-        pub fn from_physical_address(physical: PhysicalAddress) *@This() {
-            return @ptrFromInt(physical.virtualize());
-        }
-
-        pub fn allocate_empty() Error!*@This() {
-            const page = mem.phys.alloc_page() orelse return error.out_of_pages;
-            const table = @as(*@This(), @ptrFromInt(page.virtualize()));
-            for (0..512) |i| {
-                table.entry(i).* = .INVALID;
-            }
-            return table;
-        }
-
-        pub fn physical_address(self: *const @This()) PhysicalAddress {
-            return PhysicalAddress.from_virtualized(@intFromPtr(self));
-        }
-
         pub inline fn entry(self: *@This(), index: usize) *Entry {
             return &self.entries[index];
         }
-
-        pub usingnamespace if (Level.NextLevel) |NextLevel| struct {
-            pub fn get_next_level(self: *Table(Level), index: usize) ?*Table(NextLevel) {
-                const ent = self.entry(index);
-                if (ent.raw.v and ent.raw.is_table()) {
-                    return Table(NextLevel).from_physical_address(ent.address());
-                }
-                return null;
-            }
-
-            pub fn get_or_create_next_level(self: *Table(Level), index: usize) Error!*Table(NextLevel) {
-                const ent = self.entry(index);
-
-                if (ent.raw.v) {
-                    // TODO handle mixed hugepages + tables
-                    if (!ent.raw.is_table()) {
-                        @panic("TODO: handle mixed hugepages and tables");
-                    }
-                    // It is a table
-                    return Table(NextLevel).from_physical_address(ent.address());
-                } else {
-                    // Allocate a new entry
-                    const table = try Table(NextLevel).allocate_empty();
-                    const physical = table.physical_address();
-                    ent.* = TableEntry(Level).table(physical, .{});
-                    return table;
-                }
-            }
-        } else struct {};
     };
 }
 
-pub const ProcessAddressSpace = struct {
-    l1: *Table(L1),
-    asid: u8,
-
-    pub const Error = mem.vmm.AddressSpaceError;
-
-    var g_asid: AtomicU8 = .{ .raw = 1 };
-
-    pub fn init() Error!ProcessAddressSpace {
-        const table = try Table(L1).allocate_empty();
-        // Copy kernel's mappings
-        for (KERNEL_VIRTUAL_L1I..512) |i| {
-            table.entry(i).* = g_fixed.entry(i).*;
-        }
-        const asid = g_asid.fetchAdd(1, .seq_cst);
-        return .{ .l1 = table, .asid = asid };
-    }
-
-    pub fn physical_address(self: *const @This()) PhysicalAddress {
-        return self.l1.physical_address();
-    }
-
-    pub fn map_page(self: *@This(), virtual: usize, physical: PhysicalAddress) Error!void {
-        // TODO align check on both virtual and physical
-
-        const l1i = L1.index(virtual);
-        const l2i = L2.index(virtual);
-        const l3i = L3.index(virtual);
-
-        const l2 = try self.l1.get_or_create_next_level(l1i);
-        const l3 = try l2.get_or_create_next_level(l2i);
-
-        const entry = l3.entry(l3i);
-
-        if (entry.raw.v) {
-            @panic("TODO: handle already present");
-        }
-
-        entry.* = TableEntry(L3).page(physical, .{
-            .r = true,
-            .w = true,
-            .x = true,
-            .u = true,
-        });
-        flush_vma_asid(virtual, self.asid);
-
-        log.debug("Map 0x{x} -> page 0x{x}", .{ virtual, physical.raw });
-    }
-};
-
 var g_fixed = Table(L1).empty();
 var g_fixed_lock: sync.Spinlock = .{};
-pub var g_kernel_real_base: u64 = undefined;
-extern var __kernel_start: u8;
 
 pub fn virtualize_range() usize {
     return EARLY_MAPPING_SIZE * L1.SIZE;
 }
 
-pub fn kernel_table_physical() u64 {
-    const address = @as(usize, @intFromPtr(&g_fixed));
-    const kernel_start = @intFromPtr(&__kernel_start);
-    return address - kernel_start + g_kernel_real_base;
-}
-
 pub fn unmap_early() void {
-    // Unmap lower half
+    // Make lower half mappings non-executable
     const guard = g_fixed_lock.lock_irqsave();
     defer guard.release();
     for (0..EARLY_MAPPING_SIZE) |i| {
-        g_fixed.entry(i).* = .INVALID;
+        g_fixed.entry(i).* = .page(
+            .{ .raw = L1.address(i) },
+            .{ .r = true, .w = true },
+        );
     }
 }
 
@@ -252,20 +138,13 @@ pub fn map_early(real_address: usize) void {
         );
     }
 
-    for (0..EARLY_MAPPING_SIZE) |i| {
-        g_fixed.entry(i + VIRTUALIZE_BASE_L1I).* = .page(
-            .{ .raw = L1.address(i) },
-            .{ .r = true, .w = true },
-        );
-    }
-
     // Map 1GiB at KERNEL_VIRTUAL_BASE -> physical 1GiB where the kernel is loaded
     g_fixed.entry(KERNEL_VIRTUAL_L1I).* = .page(
         .{ .raw = L1.address(real_l1) },
         .{ .r = true, .w = true, .x = true },
     );
 
-    const address = @intFromPtr(&g_fixed);
+    const address = @as(usize, @intFromPtr(&g_fixed));
     regs.SATP.write(.{ .PPN = @intCast(address >> 12), .MODE = .sv39 });
 }
 

src/debug.zig

@@ -55,7 +55,7 @@ pub const log = struct {
     }
 
     /// Write raw byte data into the debugging output.
-    pub fn write_raw(data: []const u8) void {
+    pub fn write_waw(data: []const u8) void {
         _ = write_wrapper_fn(0, data) catch return;
     }
 

src/kernel.zig

@@ -7,7 +7,6 @@ pub const arena = @import("arena.zig");
 pub const thread = @import("thread.zig");
 pub const util = @import("util.zig");
 pub const sync = @import("sync.zig");
-pub const syscall = @import("syscall.zig");
 
 pub const log = debug.log;
 pub const vmm = mem.vmm;
@@ -17,10 +16,13 @@ pub const TRACE_PHYSICAL_ALLOCATOR: bool = false;
 
 const std = @import("std");
 
-const userspace_code = @embedFile("userspace");
-
-fn f0(arg: usize) callconv(.C) void {
-    log.info("Argument is {}", .{arg});
+fn f0(arg: usize) callconv(.C) noreturn {
+    var c: usize = 0;
+    while (true) {
+        f1(arg, c);
+        c += 1;
+        thread.yield();
+    }
 }
 
 noinline fn f1(arg: usize, c: usize) void {
@@ -36,17 +38,15 @@ noinline fn f1(arg: usize, c: usize) void {
 /// * Physical memory must be initialized.
 /// * (optional) Logging should be set up.
 pub export fn kernel_main() callconv(.C) noreturn {
+    log.write("\x1B[2J", .{});
     var a = arena.Arena.init(256 * 0x1000) orelse @panic("Could not setup kernel arena");
     thread.Queue.init_this_cpu(&a);
 
-    log.info("Userspace code size: {} bytes", .{userspace_code.len});
-    const t1 = thread.test_create_user_from_code(&a, userspace_code) catch @panic("Could not create test thread");
-
-    const t = thread.Thread.create_kernel(&a, &f0, 1234);
-    thread.enqueue(t);
-    thread.enqueue(t1);
-
-    log.info("Test", .{});
+    const pc = @intFromPtr(&f0);
+    for (0..4) |i| {
+        const t = thread.Thread.create(&a, pc, i);
+        thread.enqueue(t);
+    }
 
     thread.enter();
 }

src/mem.zig

@@ -46,7 +46,7 @@ pub const PhysicalAddress = packed struct(u64) {
     ///
     /// Panics if the virtual address provided is outside of virtualizable memory range.
     pub fn from_virtualized(virt: usize) @This() {
-        if (virt < g_virtualize_base or virt - g_virtualize_base > g_virtualize_size) {
+        if ((virt < g_virtualize_base) || (virt - g_virtualize_base > g_virtualize_size)) {
             @panic("Invalid virtualized physical address");
         }
 

src/mem/phys.zig

@@ -15,77 +15,58 @@ const Spinlock = sync.Spinlock;
 pub const MemoryRegion = struct {
     /// Name string, used to represent where the memory comes from.
     name: []const u8,
-    /// Page frame number range of the region.
+    /// Byte range of the memory region.
     range: Range(u64),
 };
 
-const Bitmap = struct {
-    data: []u64,
+/// Represents information about a single managed physical memory page.
+pub const Page = extern struct {
+    /// Reference count of the page. Zero means the page is not allocated.
+    refcount: u32 = 0,
+    unused: [3]u32 = undefined,
 
-    const Self = @This();
-
-    pub const empty: Self = .{ .data = &.{} };
-
-    fn get_bit(self: *Self, index: usize) u1 {
-        const word_index = index / 64;
-        const bit_index = index % 64;
-        const masked = self.data[word_index] & (@as(u64, 1) << @intCast(bit_index));
-        return if (masked == 0) 0 else 1;
+    /// Returns `true` if the page is allocated/used.
+    pub fn is_used(self: *const @This()) bool {
+        return self.refcount != 0;
     }
 
-    fn set_bit(self: *Self, index: usize) void {
-        const word_index = index / 64;
-        const bit_index = index % 64;
-        self.data[word_index] |= (@as(u64, 1) << @intCast(bit_index));
+    fn make_available(self: *@This()) void {
+        self.refcount = 0;
     }
 
-    fn clear_bit(self: *Self, index: usize) void {
-        const word_index = index / 64;
-        const bit_index = index % 64;
-        self.data[word_index] &= ~(@as(u64, 1) << @intCast(bit_index));
+    fn make_reserved(self: *@This()) void {
+        self.refcount = std.math.maxInt(u32);
     }
 };
 
 const PhysicalMemoryManager = struct {
-    memory_start: u64,
-    last_free: usize,
-    len: usize,
+    page_array: []Page,
+    offset: u64 = 0,
+    last_free: usize = 0,
 
-    /// Each bit represents a page, there can be more u64s than needed
-    usage_bitmap: Bitmap,
-    page_refcounters: []u32,
-
-    const empty: @This() = .{
-        .memory_start = 0,
-        .last_free = 0,
-        .len = 0,
-        .usage_bitmap = .empty,
-        .page_refcounters = &.{},
-    };
+    const RECORDS_PER_PAGE: usize = vmm.PAGE_SIZE / @sizeOf(Page);
 
     fn alloc_page(self: *@This()) ?mem.PhysicalAddress {
-        for (self.last_free..self.len) |i| {
-            if (!self.is_page_used(i)) {
-                self.page_refcounters[i] += 1;
-                self.set_page_used(i);
-                self.last_free = (i + 1) % self.len;
-                return .{ .raw = self.memory_start + i * vmm.PAGE_SIZE };
+        for (self.last_free..self.page_array.len) |i| {
+            if (self.page_array[i].refcount == 0) {
+                self.page_array[i].refcount += 1;
+                self.last_free = (i + 1) % self.page_array.len;
+                return .{ .raw = self.offset + i * vmm.PAGE_SIZE };
             }
         }
         for (0..self.last_free) |i| {
-            if (!self.is_page_used(i)) {
-                self.page_refcounters[i] += 1;
-                self.set_page_used(i);
-                self.last_free = (i + 1) % self.len;
-                return .{ .raw = self.memory_start + i * vmm.PAGE_SIZE };
+            if (self.page_array[i].refcount == 0) {
+                self.page_array[i].refcount += 1;
+                self.last_free = (i + 1) % self.page_array.len;
+                return .{ .raw = self.offset + i * vmm.PAGE_SIZE };
             }
         }
         return null;
     }
 
     fn alloc_pages(self: *@This(), count: usize) ?mem.PhysicalAddress {
-        if (self.last_free + count < self.len) {
-            if (self.alloc_from(self.last_free, self.len, count)) |p| {
+        if (self.last_free + count < self.page_array.len) {
+            if (self.alloc_from(self.last_free, self.page_array.len, count)) |p| {
                 return p;
             }
         }
@@ -94,19 +75,19 @@ const PhysicalMemoryManager = struct {
 
     fn alloc_from(self: *@This(), start: usize, end: usize, count: usize) ?mem.PhysicalAddress {
         for (start..end) |i| {
-            const taken = taken: {
-                for (0..count) |j|
-                    if (self.is_page_used(i + j))
-                        break :taken true;
-                break :taken false;
-            };
+            var taken = false;
+            for (0..count) |j| {
+                if (self.page_array[i + j].is_used()) {
+                    taken = true;
+                    break;
+                }
+            }
 
             if (!taken) {
                 for (0..count) |j| {
-                    self.page_refcounters[i + j] = 1;
-                    self.set_page_used(i + j);
+                    self.page_array[i + j].refcount = 1;
                 }
-                return .{ .raw = self.memory_start + i * vmm.PAGE_SIZE };
+                return .{ .raw = self.offset + i * vmm.PAGE_SIZE };
             }
         }
 
@@ -114,11 +95,11 @@ const PhysicalMemoryManager = struct {
     }
 
     fn valid_index(self: *@This(), page: mem.PhysicalAddress) usize {
-        if (page.raw < self.memory_start) {
+        if (page.raw < self.offset) {
             log.panic("free_page: invalid page 0x{x}: outside of the allocation range", .{page.raw});
         }
-        const index = (page.raw - self.memory_start) / vmm.PAGE_SIZE;
-        if (index >= self.len) {
+        const index = (page.raw - self.offset) / vmm.PAGE_SIZE;
+        if (index >= self.page_array.len) {
             log.panic("free_page: invalid page 0x{x}: outside of the allocation range", .{page.raw});
         }
         return index;
@@ -126,75 +107,52 @@ const PhysicalMemoryManager = struct {
 
     fn free_page(self: *@This(), page: mem.PhysicalAddress) void {
         const index = self.valid_index(page);
-        if (!self.is_page_used(index)) {
+        if (self.page_array[index].refcount == 0) {
             log.panic("free_page: double free of page 0x{x} detected", .{page.raw});
         }
-        self.page_refcounters[index] -= 1;
-        if (self.page_refcounters[index] == 0) {
-            self.clear_page_used(index);
+        self.page_array[index].refcount -= 1;
+        if (self.page_array[index].refcount == 0) {
             self.last_free = index;
         }
     }
 
-    fn is_page_used(self: *@This(), index: usize) bool {
-        return self.usage_bitmap.get_bit(index) == 1;
-    }
-
-    fn set_page_used(self: *@This(), index: usize) void {
-        self.usage_bitmap.set_bit(index);
-    }
-
-    fn clear_page_used(self: *@This(), index: usize) void {
-        self.usage_bitmap.clear_bit(index);
+    fn get_page(self: *@This(), page: mem.PhysicalAddress) *Page {
+        const index = self.valid_index(page);
+        return &self.page_array[index];
     }
 };
 
 var g_memory_regions: std.BoundedArray(MemoryRegion, 16) = .{};
 var g_reserved_regions: std.BoundedArray(MemoryRegion, 16) = .{};
 var g_physical_memory_lock = Spinlock{};
-var g_physical_memory = PhysicalMemoryManager.empty;
+var g_physical_memory = PhysicalMemoryManager{ .page_array = undefined };
 
 /// Adds an available memory region to the list.
 ///
-/// `base` and `size` are in bytes. Regions are page-aligned "inwards", meaning the function will
-/// only add the range of full pages of the specified region. If a combination is provided that
-/// does not yield any full 4KiB pages (e.g. `base=0x1234, size=0x123`), it is ignored.
-///
 /// # Note
 ///
 /// Only meaningful to call before calling `init()`.
 pub fn add_memory_region(name: []const u8, base: u64, size: u64) void {
     log.info("Memory: '{s}', base 0x{x}, size 0x{x}", .{ name, base, size });
-    const start = vmm.L3.align_up(base) / vmm.L3.SIZE;
-    const len = vmm.L3.align_down(base + size) / vmm.L3.SIZE - start;
-    if (len > 0) {
-        g_memory_regions.append(.{ .name = name, .range = .{ .start = start, .len = len } }) //
-        catch @panic("memory regions overflow");
-    }
+    g_memory_regions.append(.{ .name = name, .range = .{ .start = base, .len = size } }) //
+    catch @panic("memory regions overflow");
 }
 
 /// Adds an reserved memory region to the list.
 ///
-/// `base` and `size` are in bytes. Regions are page-aligned "outwards", meaning that the
-/// reservation extends to any pages affected by the specified region.
-///
 /// # Note
 ///
 /// Only meaningful to call before calling `init()`.
 pub fn add_reserved_region(name: []const u8, base: u64, size: u64) void {
     log.info("Reserved: '{s}', base 0x{x}, size 0x{x}", .{ name, base, size });
-    const start = base / vmm.L3.SIZE;
-    const len = vmm.L3.align_up(base + size) / vmm.L3.SIZE - start;
-    if (len > 0) {
-        g_reserved_regions.append(.{ .name = name, .range = .{ .start = start, .len = len } }) //
-        catch @panic("reserved regions overflow");
-    }
+    g_reserved_regions.append(.{ .name = name, .range = .{ .start = base, .len = size } }) //
+    catch @panic("reserved regions overflow");
 }
 
-fn is_reserved_in(page_index: u64) ?*const MemoryRegion {
+fn is_reserved_in(page: u64) ?*const MemoryRegion {
     for (0..g_reserved_regions.len) |i| {
         const region = &g_reserved_regions.buffer[i];
-        if (page_index >= region.range.start and page_index < region.range.end()) {
+        if (page >= region.range.start and page < region.range.end()) {
             return region;
         }
     }
@@ -206,7 +164,7 @@ fn alloc_from_region(region: *const MemoryRegion, reason: []const u8, page_count
     while (offset < region.range.len) {
         var taken: ?*const MemoryRegion = null;
         for (0..page_count) |i| {
-            if (is_reserved_in(region.range.start + offset + i)) |resv| {
+            if (is_reserved_in(region.range.start + offset + i * vmm.PAGE_SIZE)) |resv| {
                 taken = resv;
                 break;
             }
@@ -217,51 +175,27 @@ fn alloc_from_region(region: *const MemoryRegion, reason: []const u8, page_count
             continue;
         }
 
-        const base = (region.range.start + offset) * vmm.L3.SIZE;
+        const base = region.range.start + offset;
         add_reserved_region(reason, base, page_count * vmm.PAGE_SIZE);
         return base;
     }
     return null;
 }
 
-/// Allocates a slice of type `T` that spans the `page_count` pages.
-fn alloc_slice_pages(comptime T: type, reason: []const u8, page_count: usize) []T {
+fn alloc_page_array(page_count: usize) []Page {
     for (g_memory_regions.constSlice()) |region| {
-        if (alloc_from_region(&region, reason, page_count)) |physAddress| {
+        if (alloc_from_region(&region, "page-array", page_count)) |physAddress| {
             const vaddr = (mem.PhysicalAddress{ .raw = physAddress }).virtualize();
-            const len = (page_count * vmm.PAGE_SIZE) / @sizeOf(T);
-            const ptr: [*]T = @ptrFromInt(vaddr);
-            const slice: []T = ptr[0..len];
+            const len = page_count * PhysicalMemoryManager.RECORDS_PER_PAGE;
+            const ptr: [*]Page = @ptrFromInt(vaddr);
+            const slice: []Page = ptr[0..len];
+            for (0..len) |i| {
+                slice[i].refcount = std.math.maxInt(u32);
+            }
             return slice;
         }
     }
-    @panic("Failed to allocate a slice");
-}
-
-/// Allocates a slice of type `T` that has at least `min_len` items, allocates in 4KiB pages.
-/// The items are zeroed out.
-fn alloc_slice(comptime T: type, reason: []const u8, min_len: usize) []T {
-    const min_alloc_bytes = min_len * @sizeOf(T);
-    // Round up to make sure we have enough space for the data
-    const needed_pages = vmm.L3.page_count(min_alloc_bytes);
-    const slice = alloc_slice_pages(T, reason, needed_pages);
-    const slice_as_bytes = std.mem.sliceAsBytes(slice);
-    @memset(slice_as_bytes, 0);
-    return slice;
-}
-
-/// Allocates a bitmap that has at least `bits_required` total bits.
-/// It can have more since we allocate 4KiB pages and the backing type is []u64
-fn alloc_bitmap(bits_required: usize) Bitmap {
-    // Round up to the upper u64 that has at least `pages` bits
-    const bitmap_entries = (bits_required + 63) / 64;
-    const bitmap = alloc_slice(u64, "bitmap", bitmap_entries);
-    return .{ .data = bitmap };
-}
-fn alloc_refcounters(count: usize) []u32 {
-    const refcounters = alloc_slice(u32, "refcounters", count);
-    @memset(refcounters, std.math.maxInt(u32));
-    return refcounters;
+    @panic("TODO");
 }
 
 /// Initializes the physical memory management.
@@ -275,7 +209,6 @@ pub fn init() void {
     var memory_end: u64 = std.math.minInt(u64);
 
     for (g_memory_regions.constSlice()) |region| {
-        log.info("Region: {}..{}", .{ region.range.start, region.range.end() });
         if (region.range.start < memory_start) {
             memory_start = region.range.start;
         }
@@ -284,43 +217,37 @@ pub fn init() void {
         }
     }
 
-    const memory_pages = memory_end - memory_start; // == bitmap bits required
-    var bitmap = alloc_bitmap(memory_pages);
-    const refcounters = alloc_refcounters(memory_pages);
+    const memory_pages = (memory_end - memory_start) / vmm.PAGE_SIZE; // == bitmap bits required
+    const page_array_pages = (memory_pages + PhysicalMemoryManager.RECORDS_PER_PAGE - 1) //
+        / PhysicalMemoryManager.RECORDS_PER_PAGE;
 
+    const page_array = alloc_page_array(page_array_pages);
     var available_pages: usize = 0;
 
     for (g_memory_regions.constSlice()) |region| {
-        const offset = region.range.start - memory_start;
-        for (0..region.range.len) |i| {
-            refcounters[offset + i] = 0;
+        const offset = (region.range.start - memory_start) / vmm.PAGE_SIZE;
+        for (0..region.range.len / vmm.PAGE_SIZE) |i| {
+            page_array[offset + i].make_available();
             available_pages += 1;
         }
     }
     for (g_reserved_regions.constSlice()) |region| {
-        const offset = region.range.start - memory_start;
-        for (0..region.range.len) |i| {
-            if (offset + i >= memory_pages) {
+        const offset = (region.range.start - memory_start) / vmm.PAGE_SIZE;
+        for (0..region.range.len / vmm.PAGE_SIZE) |i| {
+            if (offset + i >= page_array.len) {
                 break;
             }
-            refcounters[offset + i] = std.math.maxInt(u32);
-            bitmap.set_bit(offset + i);
-
+            page_array[offset + i].make_reserved();
             available_pages -= 1;
         }
     }
 
     var size_fmt: [64]u8 = undefined;
     const size_fmt_str = mem.format_size(&size_fmt, available_pages * vmm.PAGE_SIZE);
-    log.info(
-        "Available memory: {s}, bitmap {*}, refcounts {*}",
-        .{ size_fmt_str, bitmap.data, refcounters },
-    );
+    log.info("Available memory: {s}, page array {*}", .{ size_fmt_str, page_array });
 
-    g_physical_memory.len = memory_pages;
-    g_physical_memory.memory_start = memory_start * vmm.L3.SIZE;
-    g_physical_memory.usage_bitmap = bitmap;
-    g_physical_memory.page_refcounters = refcounters;
+    g_physical_memory.page_array = page_array;
+    g_physical_memory.offset = memory_start;
 }
 
 fn trace_allocation(count: usize, page: ?mem.PhysicalAddress) void {
@@ -372,3 +299,16 @@ pub fn free_page(page: mem.PhysicalAddress) void {
     defer guard.release();
     g_physical_memory.free_page(page);
 }
+
+/// Returns a `Page` struct representing the given `page`.
+///
+/// # Invariants
+///
+/// The physical memory lock must be held.
+///
+/// # Panics
+///
+/// Will panic if the `page` does not represent a valid managed page.
+pub fn get_page(page: mem.PhysicalAddress) *Page {
+    return g_physical_memory.get_page(page);
+}

src/mem/vmalloc.zig

@@ -1,443 +0,0 @@
-const std = @import("std");
-
-const Arena = @import("../arena.zig").Arena;
-const Range = @import("../util/range.zig").Range;
-
-/// Describes a single virtual memory range.
-///
-/// Used by `VirtualMemoryAllocator` to track allocated/used regions.
-pub const VirtualMemoryRange = struct {
-    range: Range(u64),
-
-    prev: ?*VirtualMemoryRange = null,
-    next: ?*VirtualMemoryRange = null,
-};
-
-/// Virtual memory allocator implementation.
-pub const VirtualMemoryAllocator = struct {
-    arena: *Arena,
-    head: ?*VirtualMemoryRange = null,
-    outer_range: Range(u64),
-
-    /// One of errors returned by the allocation logic + underlying allocator error.
-    pub const Error = error{ already_exists, invalid_region, cannot_fit };
-
-    pub const DrainIterator = struct {
-        vma: *VirtualMemoryAllocator,
-
-        pub fn next(self: *@This()) ?Range(u64) {
-            while (self.vma.head) |head| {
-                self.vma.head = head.next;
-                const range = head.range;
-                // TODO free the range
-                return range;
-            }
-            return null;
-        }
-    };
-
-    /// An iterator over VM regions being freed.
-    pub const FreeIterator = struct {
-        range: Range(u64),
-        vma: *VirtualMemoryAllocator,
-        current: ?*VirtualMemoryRange,
-
-        pub fn next(self: *@This()) Error!?Range(u64) {
-            while (self.current) |n| {
-                if (n.range.intersect(&self.range)) |xs| {
-                    if (xs.start == n.range.start) {
-                        if (xs.end() == n.range.end()) {
-                            // Whole range encompassed by requested range
-                            // Unlink the node
-                            if (n.next) |nn| {
-                                nn.prev = n.prev;
-                            }
-                            if (n.prev) |np| {
-                                np.next = n.next;
-                            } else {
-                                self.vma.head = n.next;
-                            }
-                            // Free it
-                            self.current = n.next;
-                            // self.vma.arena.destroy(n);
-
-                            return xs;
-                        }
-
-                        // Remove space from the start
-                        n.range.start += xs.len;
-                        n.range.len -= xs.len;
-                        // Does not touch the end, so can be sure this is the last node
-                        self.current = null;
-                        return xs;
-                    } else if (xs.end() == n.range.end()) {
-                        n.range.len -= xs.len;
-                        // Continue, there might be a following node affected
-                        self.current = n.next;
-                        return xs;
-                    } else {
-                        // Insert a new node after the current one
-                        const new_node = self.vma.arena.create(VirtualMemoryRange);
-                        new_node.* = VirtualMemoryRange{
-                            .range = .{ .start = xs.end(), .len = n.range.end() - xs.end() },
-                            .prev = n,
-                            .next = n.next,
-                        };
-                        n.range.len = xs.start - n.range.start;
-                        if (n.next) |nn| {
-                            nn.prev = new_node;
-                        }
-                        n.next = new_node;
-                        // Requested region is fully encompassed by this one, so no intersections
-                        // will follow
-                        self.current = null;
-                        return xs;
-                    }
-                } else {
-                    // No intersect
-                    self.current = n.next;
-                }
-            }
-            return null;
-        }
-    };
-
-    /// Creates a new instance of a virtual memory allocator.
-    pub fn init(arena: *Arena, outer_range: Range(u64)) @This() {
-        return .{
-            .outer_range = outer_range,
-            .arena = arena,
-        };
-    }
-
-    /// Allocates a free region of virtual memory of requested (`pfn_count`) size.
-    ///
-    /// # Errors
-    ///
-    /// * `cannot_fit` - if no free space found to fit the requested allocation.
-    /// * Underlying allocator error - if allocation of a new node fails.
-    pub fn allocate(self: *@This(), pfn_count: u64) Error!u64 {
-        // Try to fit before first entry
-        const gap_before_first = if (self.head) |n| (n.range.start - self.outer_range.start) else self.outer_range.len;
-
-        if (gap_before_first >= pfn_count) {
-            var new_node = self.arena.create(VirtualMemoryRange);
-
-            new_node.range = .{ .start = self.outer_range.start, .len = pfn_count };
-            new_node.next = self.head;
-            new_node.prev = null;
-
-            if (self.head) |n| {
-                n.prev = new_node;
-            }
-
-            self.head = new_node;
-
-            return self.outer_range.start;
-        }
-
-        // If cannot fit before first entry, find an entry to fit after
-        var node = self.head;
-        while (node) |n| {
-            const gap =
-                if (n.next) |nn|
-                    // Gap between this and next
-                    (nn.range.start - n.range.end())
-                else
-                    // Gap between this and the end
-                    (self.outer_range.end() - n.range.end());
-
-            if (gap >= pfn_count) {
-                // Insert after this
-                const result = n.range.end();
-                var new_node = self.arena.create(VirtualMemoryRange);
-                new_node.prev = n;
-                new_node.next = n.next;
-                new_node.range = .{ .start = result, .len = pfn_count };
-                if (n.next) |nn| {
-                    nn.prev = new_node;
-                }
-                n.next = new_node;
-                return result;
-            }
-
-            node = n.next;
-        }
-
-        return error.cannot_fit;
-    }
-
-    /// Inserts a reservation into the VM allocator.
-    ///
-    /// # Errors
-    ///
-    /// * `already_exists` - if the requested range intersects existing ranges.
-    /// * Underlying allocator error - if allocation of a new node fails.
-    pub fn insert(self: *@This(), region: Range(u64)) Error!void {
-        // Validate that the range does not escape the outer range
-        if (region.start < self.outer_range.start or region.end() > self.outer_range.end()) {
-            return error.invalid_region;
-        }
-
-        // Find the last node which is before the region supposed to be inserted
-        var node = self.head;
-        var insert_after: ?*VirtualMemoryRange = null;
-        while (node) |n| {
-            if (n.range.intersect(&region) != null) {
-                return error.already_exists;
-            }
-
-            if (n.range.end() <= region.start) {
-                insert_after = n;
-            }
-
-            node = n.next;
-        }
-
-        var new_node = self.arena.create(VirtualMemoryRange);
-
-        new_node.range = region;
-
-        if (insert_after) |ia| {
-            new_node.prev = ia;
-            new_node.next = ia.next;
-
-            if (ia.next) |ian| {
-                ian.prev = new_node;
-            }
-            ia.next = new_node;
-        } else {
-            new_node.next = null;
-            new_node.prev = null;
-
-            self.head = new_node;
-        }
-    }
-
-    /// Deallocates (shrinks/truncates) regions intersecting the requested range.
-    pub fn free(self: *@This(), start_pfn: u64, pfn_count: u64) FreeIterator {
-        const range = Range(u64){ .start = start_pfn, .len = pfn_count };
-        return FreeIterator{
-            .current = self.head,
-            .vma = self,
-            .range = range,
-        };
-    }
-
-    pub fn drain(self: *@This()) DrainIterator {
-        return DrainIterator{ .vma = self };
-    }
-};
-
-test "Inserted entries in vmalloc are properly ordered" {
-    var vma = VirtualMemoryAllocator.init(std.testing.allocator, .{ .start = 0x1000, .len = 0x2000 });
-    defer {
-        while (vma.head) |n| {
-            vma.head = n.next;
-            std.testing.allocator.destroy(n);
-        }
-    }
-    try vma.insert(.{ .start = 0x1200, .len = 0x200 });
-    {
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1200, n0.range.start);
-        try std.testing.expectEqual(0x200, n0.range.len);
-        try std.testing.expectEqual(null, n0.next);
-        try std.testing.expectEqual(null, n0.prev);
-    }
-    try vma.insert(.{ .start = 0x2000, .len = 0x200 });
-    {
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1200, n0.range.start);
-        try std.testing.expectEqual(0x200, n0.range.len);
-        try std.testing.expectEqual(null, n0.prev);
-        const n1 = n0.next.?;
-        try std.testing.expectEqual(0x2000, n1.range.start);
-        try std.testing.expectEqual(0x200, n1.range.len);
-        try std.testing.expectEqual(n0, n1.prev);
-        try std.testing.expectEqual(null, n1.next);
-    }
-    try vma.insert(.{ .start = 0x1400, .len = 0x200 });
-    {
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1200, n0.range.start);
-        try std.testing.expectEqual(0x200, n0.range.len);
-        try std.testing.expectEqual(null, n0.prev);
-        const n1 = n0.next.?;
-        try std.testing.expectEqual(0x1400, n1.range.start);
-        try std.testing.expectEqual(0x200, n1.range.len);
-        try std.testing.expectEqual(n0, n1.prev);
-        const n2 = n1.next.?;
-        try std.testing.expectEqual(0x2000, n2.range.start);
-        try std.testing.expectEqual(0x200, n2.range.len);
-        try std.testing.expectEqual(n1, n2.prev);
-        try std.testing.expectEqual(null, n2.next);
-    }
-}
-
-test "Overlapping insertions are denied" {
-    var vma = VirtualMemoryAllocator.init(std.testing.allocator, .{ .start = 0x1000, .len = 0x1000 });
-    defer {
-        while (vma.head) |n| {
-            vma.head = n.next;
-            std.testing.allocator.destroy(n);
-        }
-    }
-    try vma.insert(.{ .start = 0x1200, .len = 0x200 });
-    try std.testing.expectError(error.already_exists, vma.insert(.{ .start = 0x1100, .len = 0x200 }));
-    try std.testing.expectError(error.already_exists, vma.insert(.{ .start = 0x1300, .len = 0x200 }));
-    try std.testing.expectError(error.already_exists, vma.insert(.{ .start = 0x1100, .len = 0x400 }));
-}
-
-test "Insertions outside of bounds are denied" {
-    var vma = VirtualMemoryAllocator.init(std.testing.allocator, .{ .start = 0x1000, .len = 0x1000 });
-    // As above...
-    try std.testing.expectError(error.invalid_region, vma.insert(.{ .start = 0x2200, .len = 0x200 }));
-    // ... so below
-    try std.testing.expectError(error.invalid_region, vma.insert(.{ .start = 0x200, .len = 0x200 }));
-    // Crosses from below
-    try std.testing.expectError(error.invalid_region, vma.insert(.{ .start = 0x200, .len = 0x1000 }));
-    // Crosses into above
-    try std.testing.expectError(error.invalid_region, vma.insert(.{ .start = 0x1200, .len = 0x1000 }));
-    // Encompasses whole
-    try std.testing.expectError(error.invalid_region, vma.insert(.{ .start = 0x200, .len = 0x2000 }));
-}
-
-test "Allocations from vmalloc" {
-    var vma = VirtualMemoryAllocator.init(std.testing.allocator, .{ .start = 0x1000, .len = 0x1000 });
-    defer {
-        while (vma.head) |n| {
-            vma.head = n.next;
-            std.testing.allocator.destroy(n);
-        }
-    }
-    try vma.insert(.{ .start = 0x1200, .len = 0x200 });
-    try std.testing.expectEqual(0x1000, try vma.allocate(0x100));
-    try std.testing.expectEqual(0x1400, try vma.allocate(0x400));
-    try std.testing.expectEqual(0x1100, try vma.allocate(0x100));
-}
-
-test "vmalloc free" {
-    var vma = VirtualMemoryAllocator.init(std.testing.allocator, .{ .start = 0x1000, .len = 0x1000 });
-
-    try vma.insert(.{ .start = 0x1200, .len = 0x800 });
-    try vma.insert(.{ .start = 0x1A00, .len = 0x400 });
-
-    // Remove nothing
-    {
-        var free_it = vma.free(0x1000, 0x200);
-        try std.testing.expectEqual(null, free_it.next());
-    }
-
-    // Remove a chunk in the middle of a node
-    {
-        var free_it = vma.free(0x1400, 0x400);
-        const r0 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1400, r0.start);
-        try std.testing.expectEqual(0x400, r0.len);
-        try std.testing.expectEqual(null, free_it.next());
-
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1200, n0.range.start);
-        try std.testing.expectEqual(0x200, n0.range.len);
-        const n1 = n0.next.?;
-        try std.testing.expectEqual(0x1800, n1.range.start);
-        try std.testing.expectEqual(0x200, n1.range.len);
-        try std.testing.expectEqual(n0, n1.prev);
-        const n2 = n1.next.?;
-        try std.testing.expectEqual(0x1A00, n2.range.start);
-        try std.testing.expectEqual(0x400, n2.range.len);
-        try std.testing.expectEqual(n1, n2.prev);
-        try std.testing.expectEqual(null, n2.next);
-    }
-
-    // Remove from the start
-    {
-        var free_it = vma.free(0x1200, 0x100);
-        const r0 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1200, r0.start);
-        try std.testing.expectEqual(0x100, r0.len);
-        try std.testing.expectEqual(null, free_it.next());
-
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1300, n0.range.start);
-        try std.testing.expectEqual(0x100, n0.range.len);
-        const n1 = n0.next.?;
-        try std.testing.expectEqual(0x1800, n1.range.start);
-        try std.testing.expectEqual(0x200, n1.range.len);
-        try std.testing.expectEqual(n0, n1.prev);
-        const n2 = n1.next.?;
-        try std.testing.expectEqual(0x1A00, n2.range.start);
-        try std.testing.expectEqual(0x400, n2.range.len);
-        try std.testing.expectEqual(n1, n2.prev);
-        try std.testing.expectEqual(null, n2.next);
-    }
-
-    // Remove from the end
-    {
-        var free_it = vma.free(0x1900, 0x100);
-        const r0 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1900, r0.start);
-        try std.testing.expectEqual(0x100, r0.len);
-        try std.testing.expectEqual(null, free_it.next());
-
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1300, n0.range.start);
-        try std.testing.expectEqual(0x100, n0.range.len);
-        const n1 = n0.next.?;
-        try std.testing.expectEqual(0x1800, n1.range.start);
-        try std.testing.expectEqual(0x100, n1.range.len);
-        try std.testing.expectEqual(n0, n1.prev);
-        const n2 = n1.next.?;
-        try std.testing.expectEqual(0x1A00, n2.range.start);
-        try std.testing.expectEqual(0x400, n2.range.len);
-        try std.testing.expectEqual(n1, n2.prev);
-        try std.testing.expectEqual(null, n2.next);
-    }
-
-    // Remove single full
-    {
-        var free_it = vma.free(0x1000, 0x600);
-        const r0 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1300, r0.start);
-        try std.testing.expectEqual(0x100, r0.len);
-        try std.testing.expectEqual(null, free_it.next());
-
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1800, n0.range.start);
-        try std.testing.expectEqual(0x100, n0.range.len);
-        const n1 = n0.next.?;
-        try std.testing.expectEqual(0x1A00, n1.range.start);
-        try std.testing.expectEqual(0x400, n1.range.len);
-        try std.testing.expectEqual(n0, n1.prev);
-        try std.testing.expectEqual(null, n1.next);
-    }
-
-    // Remove one full + one partial
-    {
-        var free_it = vma.free(0x1600, 0x600);
-        const r0 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1800, r0.start);
-        try std.testing.expectEqual(0x100, r0.len);
-        const r1 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1A00, r1.start);
-        try std.testing.expectEqual(0x200, r1.len);
-        try std.testing.expectEqual(null, free_it.next());
-
-        const n0 = vma.head.?;
-        try std.testing.expectEqual(0x1C00, n0.range.start);
-        try std.testing.expectEqual(0x200, n0.range.len);
-        try std.testing.expectEqual(null, n0.next);
-    }
-
-    // Remove whatever remains
-    {
-        var free_it = vma.free(0, 0x20000);
-        const r0 = (try free_it.next()).?;
-        try std.testing.expectEqual(0x1C00, r0.start);
-        try std.testing.expectEqual(0x200, r0.len);
-        try std.testing.expectEqual(null, free_it.next());
-
-        try std.testing.expectEqual(null, vma.head);
-    }
-}

src/mem/vmm.zig

@@ -1,31 +1,13 @@
 //! Platform-independent virtual memory management definitions.
 
-const mem = @import("../mem.zig");
-const arena = @import("../arena.zig");
-const vmalloc = @import("vmalloc.zig");
-const kernel = @import("../kernel.zig");
-const sync = @import("../sync.zig");
-
-const arch = kernel.arch;
-const log = kernel.log;
-const Arena = arena.Arena;
-
-/// Last virtual memory translation level. Always 4KiB on all platforms.
-pub const L3 = mem.TranslationLevel(12, null);
-
 /// Page size is 4KiB on all platforms.
-pub const PAGE_SIZE: usize = L3.SIZE;
-
-pub const AddressSpaceError = error{
-    out_of_pages,
-} || vmalloc.VirtualMemoryAllocator.Error;
+pub const PAGE_SIZE: usize = 0x1000;
 
 /// Helper function to construct a "Translation Level" struct type from a bit shift.
-pub fn TranslationLevel(comptime shift: usize, comptime Next: ?type) type {
+pub fn TranslationLevel(comptime shift: usize) type {
     return struct {
         pub const SHIFT: usize = shift;
         pub const SIZE: usize = 1 << shift;
-        pub const NextLevel = Next;
 
         pub inline fn index(addr: usize) usize {
             return (addr >> shift) & 511;
@@ -46,62 +28,5 @@ pub fn TranslationLevel(comptime shift: usize, comptime Next: ?type) type {
         pub inline fn align_up(addr: usize) usize {
             return (addr + SIZE - 1) & ~(SIZE - 1);
         }
-
-        pub inline fn page_number(addr: usize) usize {
-            return addr >> shift;
-        }
-
-        pub inline fn page_count(size: usize) usize {
-            return (size + SIZE - 1) / SIZE;
-        }
     };
 }
-
-pub const ProcessAddressSpace = struct {
-    inner: arch.vmm.ProcessAddressSpace,
-    allocator: vmalloc.VirtualMemoryAllocator,
-    lock: sync.Spinlock,
-
-    pub fn init(a: *Arena) AddressSpaceError!ProcessAddressSpace {
-        // 0x200000..0x600000
-        const inner = try arch.vmm.ProcessAddressSpace.init();
-        const allocator = vmalloc.VirtualMemoryAllocator.init(a, .{ .start = 512, .len = 1024 });
-
-        return .{ .inner = inner, .allocator = allocator, .lock = .{} };
-    }
-
-    pub fn clear(self: *@This()) void {
-        var drain = self.allocator.drain();
-        while (drain.next()) |range| {
-            log.info("Free range: 0x{x}..0x{x}", .{ range.start * L3.SIZE, range.end() * L3.SIZE });
-            // TODO unmap/free pages
-        }
-    }
-
-    pub fn map_single_page(
-        self: *@This(),
-        virtual: usize,
-        physical: mem.PhysicalAddress,
-    ) AddressSpaceError!void {
-        self.lock.lock();
-        defer self.lock.release();
-
-        try self.allocator.insert(.{ .start = L3.page_number(virtual), .len = 1 });
-        errdefer {
-            var it = self.allocator.free(L3.page_number(virtual), 1);
-            while (it.next() catch unreachable) |n| {
-                // TODO: inner.unmap_page()
-                _ = n;
-            }
-        }
-        try self.inner.map_page(virtual, physical);
-    }
-
-    pub fn physical_address(self: *const @This()) mem.PhysicalAddress {
-        return self.inner.physical_address();
-    }
-
-    pub fn asid(self: *const @This()) u64 {
-        return self.inner.asid;
-    }
-};

src/object.zig

@@ -1,103 +0,0 @@
-const mem = @import("mem.zig");
-const kernel = @import("kernel.zig");
-const thread = @import("thread.zig");
-const abi = @import("abi");
-
-const ProcessAddressSpace = mem.vmm.ProcessAddressSpace;
-const log = kernel.log;
-const Thread = thread.Thread;
-
-pub const PhysicalMemoryObject = struct {
-    fn send(self: *const PhysicalMemoryObject, caller: *Thread, message: *const [5]usize) usize {
-        _ = self;
-        _ = caller;
-        _ = message;
-        @panic("TODO: physical memory object messaging");
-    }
-
-    fn sendrecv(self: *const PhysicalMemoryObject, caller: *Thread, message: *[5]usize) usize {
-        switch (@as(abi.PhysicalMemoryObjectAction, @enumFromInt(message[0]))) {
-            .ZO_physical_memory_allocate => {
-                // TODO somehow track ownership of the memory by the process
-                const pages = mem.phys.alloc_pages(message[1]) orelse {
-                    return 1;
-                };
-                log.info("{*}: allocated {} pages: 0x{x}", .{caller, message[1], pages.raw});
-                message[0] = pages.raw;
-                return 0;
-            },
-            .ZO_physical_memory_free => {
-                @panic("TODO: ZO_physical_memory_free");
-            },
-            else => {
-                @panic("TODO: invalid message to Physical Memory Object");
-            }
-        }
-        _ = self;
-    }
-};
-
-pub const ProcessObject = struct {
-    inner: *Thread,
-
-    fn send(self: *const ProcessObject, caller: *Thread, message: *const [5]usize) usize {
-        _ = self;
-        // TODO define this in IDL/ABI
-        switch (@as(abi.ProcessObjectAction, @enumFromInt(message[0]))) {
-            .ZO_process_exit => {
-                log.info("{*} exited with code 0x{x} ({})", .{caller, message[1], message[1]});
-                Thread.exit_current();
-            },
-            else => {
-                @panic("TODO: invalid message to Process Object");
-            }
-        }
-    }
-
-    fn sendrecv(self: *const ProcessObject, caller: *Thread, message: *[5]usize) usize {
-        _ = self;
-        _ = caller;
-        _ = message;
-        @panic("TODO: ProcessObject sendrecv()");
-    }
-};
-
-pub const DebugObject = struct {
-    fn send(self: *const DebugObject, caller: *Thread, message: *const [5]usize) usize {
-        _ = self;
-        // Debug has only one message
-        const text = @as([*]u8, @ptrFromInt(message[0]))[0..message[1]];
-        log.info("{*}: {s}", .{ caller, text });
-        return 0;
-    }
-
-    fn sendrecv(self: *const DebugObject, caller: *Thread, message: *[5]usize) usize {
-        _ = self;
-        _ = caller;
-        _ = message;
-        @panic("TODO: DebugObject sendrecv()");
-    }
-};
-
-pub const Object = union(enum) {
-    physical_memory: PhysicalMemoryObject,
-    process: ProcessObject,
-    debug: DebugObject,
-    // TODO userspace "object" can be placed here
-
-    pub fn send(self: Object, caller: *Thread, message: *const [5]usize) usize {
-        return switch (self) {
-            .physical_memory => |physical_memory| physical_memory.send(caller, message),
-            .process => |process| process.send(caller, message),
-            .debug => |debug| debug.send(caller, message),
-        };
-    }
-
-    pub fn sendrecv(self: Object, caller: *Thread, message: *[5]usize) usize {
-        return switch (self) {
-            .physical_memory => |physical_memory| physical_memory.sendrecv(caller, message),
-            .process => |process| process.sendrecv(caller, message),
-            .debug => |debug| debug.sendrecv(caller, message),
-        };
-    }
-};

src/syscall.zig

@@ -1,55 +0,0 @@
-const kernel = @import("kernel.zig");
-const abi = @import("abi");
-
-const thread = kernel.thread;
-const Thread = thread.Thread;
-const log = kernel.log;
-
-pub const SyscallFn = *const fn (*Thread, *[6]usize) void;
-
-pub const syscall_table: [abi.MAX_SYSCALL]?SyscallFn = make_syscall_table();
-
-fn make_syscall_table() [abi.MAX_SYSCALL]?SyscallFn {
-    const SC = abi.SyscallNumber;
-    var array = [_]?SyscallFn{undefined} ** abi.MAX_SYSCALL;
-    array[@intFromEnum(SC.SYS_send)] = sys_send;
-    array[@intFromEnum(SC.SYS_recv)] = sys_recv;
-    array[@intFromEnum(SC.SYS_sendrecv)] = sys_sendrecv;
-    return array;
-}
-
-fn sys_send(cthread: *Thread, frame: *[6]usize) void {
-    const handle: abi.Handle = @enumFromInt(frame[0]);
-    const object = cthread.handle(handle) orelse {
-        @panic("TODO: userspace invoked non-existent handle");
-    };
-    frame[0] = object.send(cthread, frame[1..6]);
-}
-
-fn sys_recv(cthread: *Thread, frame: *[6]usize) void {
-    _ = cthread;
-    _ = frame;
-    @panic("TODO: SYS_recv()");
-}
-
-fn sys_sendrecv(cthread: *Thread, frame: *[6]usize) void {
-    const handle: abi.Handle = @enumFromInt(frame[0]);
-    const object = cthread.handle(handle) orelse {
-        @panic("TODO: userspace invoked non-existent handle");
-    };
-    frame[0] = object.sendrecv(cthread, frame[1..6]);
-}
-
-fn sys_undefined_syscall(cthread: *Thread, frame: *[6]usize) void {
-    _ = frame;
-    log.warn("{*} invoked an undefined syscall", .{cthread});
-    Thread.exit_current();
-}
-
-pub fn syscall_handler(func: usize, frame: *[6]usize) void {
-    const cthread = thread.Thread.current();
-    const handler = if (func >= abi.MAX_SYSCALL) sys_undefined_syscall //
-        else syscall_table[func] //
-        orelse sys_undefined_syscall;
-    handler(cthread, frame);
-}

src/thread.zig

@@ -6,137 +6,6 @@ const arena = @import("arena.zig");
 const arch = @import("kernel.zig").arch;
 const log = @import("debug.zig").log;
 const mem = @import("mem.zig");
-const sync = @import("sync.zig");
-const object = @import("object.zig");
-const abi = @import("abi");
-
-const ProcessAddressSpace = mem.vmm.ProcessAddressSpace;
-const Object = object.Object;
-const Handle = abi.Handle;
-
-// TODO: are kernel threads needed at all if we're doing a microkernel?
-
-/// Signature for kernel thread entry
-pub const KernelThreadFn = fn (usize) callconv(.C) void;
-
-pub fn kernel_return() callconv(.C) noreturn {
-    Thread.exit_current();
-}
-
-/// Task to run when there are no real threads in the queue
-pub fn idle_function(arg: usize) callconv(.C) noreturn {
-    _ = arg;
-    while (true) {
-        arch.wait_for_interrupt();
-    }
-}
-
-/// Represents a single execution thread.
-pub const Thread = struct {
-    const MAX_HANDLES: usize = 64;
-
-    /// Arena.
-    allocator: *arena.Arena,
-    /// Architecture-specific task context.
-    arch_context: arch.Context,
-
-    /// Queue to which this thread belongs
-    queue: ?*Queue = null,
-    /// Next thread in the queue.
-    next: ?*Thread = null,
-    /// Previous thread in the queue.
-    prev: ?*Thread = null,
-
-    // TODO move to process
-    address_space: ?ProcessAddressSpace = null,
-    // TODO move to process
-    handle_table: [MAX_HANDLES]?Object = [_]?Object{null} ** MAX_HANDLES,
-
-    pub const Error = error{out_of_memory} || mem.vmm.AddressSpaceError;
-
-    /// Creates a new (kernel) thread with given `function` and `arg`ument.
-    pub fn create_kernel(a: *arena.Arena, function: *const KernelThreadFn, arg: usize) *Thread {
-        const thread = a.create(Thread);
-        thread.* = .{
-            .allocator = a,
-            .arch_context = arch.Context.kernel(function, arg),
-        };
-        return thread;
-    }
-
-    pub fn create_user(
-        a: *arena.Arena,
-        address_space: ProcessAddressSpace,
-        pc: usize,
-        sp: usize,
-        arg: usize,
-    ) *Thread {
-        const thread = a.create(Thread);
-        thread.* = .{
-            .allocator = a,
-            .address_space = address_space,
-            .arch_context = arch.Context.user(&address_space, pc, sp, arg),
-        };
-        // "self" process object is granted to all processes
-        const process_object = Object{ .process = object.ProcessObject {
-            .inner = thread,
-        } };
-        _ = thread.grant(process_object);
-        return thread;
-    }
-
-    /// Enters the thread, does not return.
-    pub fn enter(self: *@This()) noreturn {
-        self.arch_context.enter();
-    }
-
-    /// Switches from `from` to `self` thread.
-    pub fn switch_from(self: *@This(), from: *@This()) void {
-        self.arch_context.switch_from(&from.arch_context);
-    }
-
-    pub fn grant(self: *@This(), obj: Object) Handle {
-        for (0..MAX_HANDLES) |i| {
-            if (self.handle_table[i] == null) {
-                self.handle_table[i] = obj;
-                return @enumFromInt(i + 1);
-            }
-        }
-        @panic("TODO: ran out of objects");
-    }
-
-    pub fn handle(self: *@This(), h: Handle) ?Object {
-        const index = @as(usize, @intFromEnum(h));
-        if (index > MAX_HANDLES or index == 0) {
-            return null;
-        }
-        return self.handle_table[index - 1];
-    }
-
-    pub fn dequeue(self: *@This()) void {
-        // TODO queueing information should be put under a lock for SMP to work properly
-        if (self.queue) |q| {
-            q.dequeue(self);
-        }
-    }
-
-    pub fn current() *@This() {
-        return Queue.t_this_cpu.?.current.?;
-    }
-
-    pub fn exit_current() noreturn {
-        // Mask IRQs so they don't break current thread's state
-        const mask = arch.IrqGuard.acquire();
-        defer mask.release();
-
-        const curr = Thread.current();
-        curr.dequeue();
-
-        yield();
-
-        @panic("This code should not be reachable");
-    }
-};
 
 /// Per-CPU thread queue structure.
 pub const Queue = struct {
@@ -146,8 +15,6 @@ pub const Queue = struct {
     current: ?*Thread = null,
     /// Thread queue head pointer.
     head: ?*Thread = null,
-    /// Queue's lock
-    lock: sync.Spinlock = .{},
 
     /// Pointer to this CPU's thread queue.
     pub threadlocal var t_this_cpu: ?*Queue = null;
@@ -173,7 +40,6 @@ pub const Queue = struct {
 
     /// Yields CPU to the next available task.
     pub fn yield(self: *@This()) void {
-        // TODO locking here
         if (self.current) |curr| {
             // Switching from thread
             if (curr.next) |next| {
@@ -182,12 +48,6 @@ pub const Queue = struct {
                     self.current = next;
                     next.switch_from(curr);
                 }
-            } else if (self.head) |h| {
-                // ... to thread (head)
-                if (h != curr) {
-                    self.current = h;
-                    h.switch_from(curr);
-                }
             } else {
                 // ... to idle
                 self.current = null;
@@ -207,11 +67,6 @@ pub const Queue = struct {
 
     /// Adds an available task to this queue.
     pub fn enqueue(self: *@This(), t: *Thread) void {
-        var guard = self.lock.lock_irqsave();
-        defer guard.release();
-
-        t.queue = self;
-
         if (self.head) |gt| {
             t.next = gt;
             t.prev = gt.prev;
@@ -223,43 +78,38 @@ pub const Queue = struct {
             t.prev = t;
         }
     }
+};
 
-    /// # Invariants
-    ///
-    /// `t` must be a thread within the `self` queue.
-    fn dequeue(self: *@This(), t: *Thread) void {
-        var guard = self.lock.lock_irqsave();
-        defer guard.release();
+/// Represents a single execution thread.
+pub const Thread = struct {
+    /// Arena.
+    allocator: *arena.Arena,
+    /// Architecture-specific task context.
+    arch_context: arch.Context,
 
-        t.queue = null;
+    /// Next thread in the queue.
+    next: ?*Thread = null,
+    /// Previous thread in the queue.
+    prev: ?*Thread = null,
 
-        if (t == self.head) {
-            if (t.next == t) {
-                self.head = null;
-                t.next = null;
-                t.prev = null;
-                return;
-            }
+    /// Creates a new (kernel) thread with given `pc` (entry point) and `arg`ument.
+    pub fn create(a: *arena.Arena, pc: usize, arg: usize) *Thread {
+        const thread = a.create(Thread);
+        thread.* = .{
+            .allocator = a,
+            .arch_context = arch.Context.kernel(pc, arg),
+        };
+        return thread;
+    }
 
-            if (t.next) |tn| {
-                tn.prev = t.prev;
-            }
-            if (t.prev) |tp| {
-                tp.next = t.next;
-            }
+    /// Enters the thread, does not return.
+    pub fn enter(self: *@This()) noreturn {
+        self.arch_context.enter();
+    }
 
-            self.head = t.next;
-        } else {
-            if (t.next) |tn| {
-                tn.prev = t.prev;
-            }
-            if (t.prev) |tp| {
-                tp.next = t.next;
-            }
-        }
-
-        t.next = null;
-        t.prev = null;
+    /// Switches from `from` to `self` thread.
+    pub fn switch_from(self: *@This(), from: *@This()) void {
+        self.arch_context.switch_from(&from.arch_context);
     }
 };
 
@@ -320,49 +170,3 @@ pub fn enter() noreturn {
 pub fn yield() void {
     Queue.t_this_cpu.?.yield();
 }
-
-pub fn test_create_user_from_code(a: *arena.Arena, code: []const u8) Thread.Error!*Thread {
-    const L3 = mem.vmm.L3;
-    const CODE_BASE: usize = 0x200000;
-
-    var address_space = try ProcessAddressSpace.init(a);
-    errdefer {
-        address_space.clear();
-    }
-
-    // @ 0x200000
-    const code_page_count = L3.page_count(code.len);
-    log.info("Code is {} pages", .{code_page_count});
-    var offset: usize = 0;
-    var address: usize = CODE_BASE;
-    while (offset < code.len) {
-        const page_offset = address % L3.SIZE;
-        const amount = @min(L3.SIZE - page_offset, code.len - offset);
-
-        const page = mem.phys.alloc_page() orelse return error.out_of_memory;
-        try address_space.map_single_page(address, page);
-
-        const page_data = @as([*]u8, @ptrFromInt(page.virtualize()))[0..amount];
-        @memcpy(page_data, code[offset .. offset + amount]);
-
-        address += amount;
-        offset += amount;
-    }
-
-    // @ 0x400000
-    const sp_base = 0x400000;
-    for (0..8) |i| {
-        const page = mem.phys.alloc_page() orelse return error.out_of_memory;
-        try address_space.map_single_page(sp_base + i * L3.SIZE, page);
-    }
-    const sp = sp_base + 8 * L3.SIZE;
-
-    log.info("Enter with sp = 0x{x}", .{sp});
-
-    const thread = Thread.create_user(a, address_space, CODE_BASE, sp, 1234);
-
-    _ = thread.grant(Object { .physical_memory = object.PhysicalMemoryObject {} });
-    _ = thread.grant(Object { .debug = object.DebugObject {} });
-
-    return thread;
-}

src/util.zig

@@ -1,4 +1,2 @@
 pub const dtb = @import("util/dtb.zig");
 pub const range = @import("util/range.zig");
-pub const btree = @import("util/btree.zig");
-pub const rangemap = @import("util/rangemap.zig");

src/util/btree.zig

@@ -1,368 +0,0 @@
-const std = @import("std");
-
-const Allocator = std.mem.Allocator;
-pub const Order = std.math.Order;
-
-pub fn CompareFn(comptime N: type) type {
-    return fn (*const N, *const N) Order;
-}
-
-pub fn SearchFn(comptime N: type, comptime C: type) type {
-    return fn (*const N, C) Order;
-}
-
-pub fn BTree(comptime N: type, comptime compare_fn: CompareFn(N), comptime deinit_fn: ?fn (*N) void) type {
-    return struct {
-        gpa: Allocator,
-        root: ?*Node = null,
-
-        pub const Error = error{ already_exists, does_not_exist } || Allocator.Error;
-
-        pub fn WalkFn(comptime C: type) type {
-            return fn (*const Node, C) void;
-        }
-
-        pub const Iterator = struct {
-            current: ?*Node,
-
-            pub fn next(self: *Iterator) ?*const Node {
-                while (self.current) |n| {
-                    const v = n;
-
-                    if (n.right) |r| {
-                        // Emit
-                        self.current = Node.leftmost(r);
-                    } else {
-                        var nn = n;
-                        while (nn.parent) |p| {
-                            if (nn == p.right) {
-                                nn = p;
-                            } else {
-                                break;
-                            }
-                        }
-                        self.current = nn.parent;
-                    }
-
-                    return v;
-                }
-
-                return null;
-            }
-        };
-
-        pub const Node = struct {
-            key: N,
-            parent: ?*Node = null,
-            left: ?*Node = null,
-            right: ?*Node = null,
-
-            fn init(a: Allocator, key: N) Error!*Node {
-                const node = try a.create(Node);
-                node.* = .{
-                    .key = key,
-                };
-                return node;
-            }
-
-            fn deinit(node: ?*Node, a: Allocator) void {
-                if (node) |n| {
-                    if (comptime deinit_fn) |f| {
-                        f(&n.key);
-                    }
-
-                    Node.deinit(n.left, a);
-                    Node.deinit(n.right, a);
-
-                    // Free node itself
-                    a.destroy(n);
-                }
-            }
-
-            fn insert(node: ?*Node, a: Allocator, key: N) Error!struct { *Node, *Node } {
-                if (node) |n| {
-                    const ord = compare_fn(&n.key, &key);
-                    var inserted: *Node = undefined;
-                    switch (ord) {
-                        .lt => {
-                            const child, inserted = try Node.insert(n.right, a, key);
-                            child.parent = n;
-                            n.right = child;
-                        },
-                        .gt => {
-                            const child, inserted = try Node.insert(n.left, a, key);
-                            child.parent = n;
-                            n.left = child;
-                        },
-                        .eq => return error.already_exists,
-                    }
-                    return .{ n, inserted };
-                } else {
-                    const n = try Node.init(a, key);
-                    return .{ n, n };
-                }
-            }
-
-            fn remove_node(node: *Node, a: Allocator, destroy: bool) ?*Node {
-                if (node.left == null) {
-                    // Only right/none
-                    const tmp = node.right;
-                    if (tmp) |t| {
-                        t.parent = node.parent;
-                    }
-                    // Destroy the node
-                    if (comptime deinit_fn) |f| {
-                        if (destroy) {
-                            f(&node.key);
-                        }
-                    }
-                    a.destroy(node);
-                    return tmp;
-                }
-                if (node.right == null) {
-                    // Only left/none
-                    const tmp = node.left;
-                    if (tmp) |t| {
-                        t.parent = node.parent;
-                    }
-                    // Destroy the node
-                    if (comptime deinit_fn) |f| {
-                        if (destroy) {
-                            f(&node.key);
-                        }
-                    }
-                    a.destroy(node);
-                    return tmp;
-                }
-
-                // Both
-                var successor = node.right;
-                while (successor) |succ| {
-                    if (succ.left) |l| {
-                        successor = l;
-                    } else {
-                        break;
-                    }
-                }
-                if (successor) |succ| {
-                    node.key = succ.key;
-                    node.right = Node.remove(node.right, a, succ.key) catch unreachable;
-                }
-                return node;
-            }
-
-            fn remove(node: ?*Node, a: Allocator, key: N) Error!?*Node {
-                if (node) |n| {
-                    const ord = compare_fn(&n.key, &key);
-                    switch (ord) {
-                        .lt => n.right = try Node.remove(n.right, a, key),
-                        .gt => n.left = try Node.remove(n.left, a, key),
-                        .eq => return Node.remove_node(n, a, true),
-                    }
-                    return node;
-                } else {
-                    return error.does_not_exist;
-                }
-            }
-
-            fn walk(node: ?*Node, ctx: anytype, walk_fn: WalkFn(@TypeOf(ctx))) void {
-                if (node) |n| {
-                    Node.walk(n.left, ctx, walk_fn);
-                    walk_fn(n, ctx);
-                    Node.walk(n.right, ctx, walk_fn);
-                }
-            }
-
-            fn leftmost(node: ?*Node) ?*Node {
-                var n = node;
-                while (n) |nn| {
-                    if (nn.left == null) {
-                        break;
-                    }
-                    n = nn.left;
-                }
-                return n;
-            }
-        };
-
-        pub fn init(a: std.mem.Allocator) @This() {
-            return .{ .gpa = a };
-        }
-
-        pub fn deinit(self: *@This()) void {
-            Node.deinit(self.root, self.gpa);
-        }
-
-        pub fn iterator(self: *@This()) Iterator {
-            return .{ .current = Node.leftmost(self.root) };
-        }
-
-        pub fn insert(self: *@This(), key: N) Error!*Node {
-            self.root, const inserted = try Node.insert(self.root, self.gpa, key);
-            return inserted;
-        }
-
-        pub fn remove(self: *@This(), key: N) Error!void {
-            self.root = try Node.remove(self.root, self.gpa, key);
-        }
-
-        pub fn remove_node(self: *@This(), node: *Node, destroy: bool) Error!void {
-            if (node.parent) |p| {
-                // Non-root node
-                const np = Node.remove_node(node, self.gpa, destroy);
-                if (np) |npp| {
-                    npp.parent = p;
-                }
-                if (node == p.right) {
-                    p.right = np;
-                } else {
-                    p.left = np;
-                }
-            } else {
-                // Root node
-                const np = Node.remove_node(node, self.gpa, destroy);
-                if (np) |npp| {
-                    npp.parent = null;
-                }
-                self.root = np;
-            }
-        }
-
-        pub fn lookup(self: *const @This(), key: N) ?*Node {
-            const search_fn = struct {
-                fn call(n: *const N, cx: N) Order {
-                    return compare_fn(n, &cx);
-                }
-            }.call;
-
-            return self.search(key, search_fn);
-        }
-
-        pub fn search(
-            self: *const @This(),
-            ctx: anytype,
-            search_fn: SearchFn(N, @TypeOf(ctx)),
-        ) ?*Node {
-            var node = self.root;
-            while (node) |n| {
-                const ord = search_fn(&n.key, ctx);
-                switch (ord) {
-                    .gt => node = n.left,
-                    .eq => return n,
-                    .lt => node = n.right,
-                }
-            }
-            return null;
-        }
-
-        pub fn walk(self: *@This(), ctx: anytype, walk_fn: WalkFn(@TypeOf(ctx))) void {
-            Node.walk(self.root, ctx, walk_fn);
-        }
-    };
-}
-
-test "BTree insertion/removal" {
-    const int_compare_fn = struct {
-        fn call(a: *const u32, b: *const u32) Order {
-            if (a.* > b.*) {
-                return .gt;
-            } else if (a.* == b.*) {
-                return .eq;
-            } else {
-                return .lt;
-            }
-        }
-    }.call;
-    const Tree = BTree(u32, int_compare_fn, null);
-    var tree = Tree.init(std.testing.allocator);
-    defer tree.deinit();
-
-    for (50..100) |i| {
-        _ = try tree.insert(@truncate(i));
-    }
-    for (1..50) |i| {
-        _ = try tree.insert(@truncate(i));
-    }
-
-    for (1..100) |i| {
-        const k = @as(u32, @truncate(i));
-        try std.testing.expectEqual(k, tree.lookup(k).?.key);
-    }
-
-    for (1..100) |i| {
-        const k = 100 - @as(u32, @truncate(i));
-        if (i % 2 == 0) {
-            try tree.remove(k);
-        }
-    }
-
-    for (1..100) |i| {
-        const k = @as(u32, @truncate(i));
-        if (i % 2 == 0) {
-            try std.testing.expectEqual(null, tree.lookup(k));
-        } else {
-            try std.testing.expectEqual(k, tree.lookup(k).?.key);
-        }
-    }
-}
-
-test "BTree removal by node" {
-    const int_compare_fn = struct {
-        fn call(a: *const u32, b: *const u32) Order {
-            if (a.* > b.*) {
-                return .gt;
-            } else if (a.* == b.*) {
-                return .eq;
-            } else {
-                return .lt;
-            }
-        }
-    }.call;
-    const Tree = BTree(u32, int_compare_fn, null);
-    var tree = Tree.init(std.testing.allocator);
-    defer tree.deinit();
-
-    _ = try tree.insert(10);
-    _ = try tree.insert(11);
-    _ = try tree.insert(12);
-
-    {
-        const n = tree.lookup(10).?;
-        try tree.remove_node(n, true);
-    }
-
-    try std.testing.expectEqual(null, tree.lookup(10));
-    try std.testing.expectEqual(12, tree.lookup(12).?.key);
-    try std.testing.expectEqual(11, tree.lookup(11).?.key);
-}
-
-test "BTree iterator" {
-    const int_compare_fn = struct {
-        fn call(a: *const u32, b: *const u32) Order {
-            if (a.* > b.*) {
-                return .gt;
-            } else if (a.* == b.*) {
-                return .eq;
-            } else {
-                return .lt;
-            }
-        }
-    }.call;
-    const Tree = BTree(u32, int_compare_fn, null);
-    var tree = Tree.init(std.testing.allocator);
-    defer tree.deinit();
-
-    for (50..100) |i| {
-        _ = try tree.insert(@truncate(i));
-    }
-    for (1..50) |i| {
-        _ = try tree.insert(@truncate(i));
-    }
-
-    var it = tree.iterator();
-    for (1..100) |i| {
-        const n = it.next().?;
-        try std.testing.expectEqual(i, n.key);
-    }
-    try std.testing.expectEqual(null, it.next());
-}

src/util/dtb.zig

@@ -487,7 +487,7 @@ pub const Fdt = struct {
 
     fn dump_property(property: *const FdtNodeProp, depth: usize, all_strings: bool) void {
         for (0..depth) |_| {
-            log.write_raw("  ");
+            log.write_waw("  ");
         }
         log.write("{s}", .{property.name});
 
@@ -510,9 +510,9 @@ pub const Fdt = struct {
             var f = true;
             while (v.next()) |s| {
                 if (f) {
-                    log.write_raw(" = ");
+                    log.write_waw(" = ");
                 } else {
-                    log.write_raw(", ");
+                    log.write_waw(", ");
                 }
                 f = false;
                 log.write("\"{s}\"", .{s});
@@ -520,17 +520,17 @@ pub const Fdt = struct {
         } else {
             // Dump the rest as a cell array
             const len = property.len_cells();
-            log.write_raw(" = <");
+            log.write_waw(" = <");
             for (0..len) |i| {
                 if (i != 0) {
-                    log.write_raw(", ");
+                    log.write_waw(", ");
                 }
                 log.write("0x{x}", .{property.get_cell_unchecked(i)});
             }
-            log.write_raw(">");
+            log.write_waw(">");
         }
 
-        log.write_raw(";\r\n");
+        log.write_waw(";\r\n");
     }
 
     fn dump_node(node: *const FdtNode, depth: usize) void {
@@ -538,12 +538,12 @@ pub const Fdt = struct {
         var first_child = true;
 
         for (0..depth) |_| {
-            log.write_raw("  ");
+            log.write_waw("  ");
         }
         if (node.name.len != 0) {
             log.write("{s} ", .{node.name});
         }
-        log.write_raw("{\r\n");
+        log.write_waw("{\r\n");
         var properties = node.prop_iterator();
         const all_strings = std.mem.eql(u8, node.name, "aliases");
         while (properties.next()) |property| {
@@ -553,13 +553,13 @@ pub const Fdt = struct {
         var children = node.children();
         while (children.next()) |child| {
             if (any_properties and first_child) {
-                log.write_raw("\r\n");
+                log.write_waw("\r\n");
             }
             first_child = false;
             dump_node(&child, depth + 1);
         }
         for (0..depth) |_| {
-            log.write_raw("  ");
+            log.write_waw("  ");
         }
         log.write("}},\r\n", .{});
     }

src/util/range.zig

@@ -1,7 +1,5 @@
 //! Utilities for manipulating ranges.
 
-const std = @import("std");
-
 /// Non-inclusive range type over `T`.
 pub fn Range(comptime T: type) type {
     return struct {
@@ -31,19 +29,5 @@ pub fn Range(comptime T: type) type {
 
             return null;
         }
-
-        pub fn contains(self: *const @This(), scalar: T) bool {
-            return scalar >= self.start and scalar - self.start < self.len;
-        }
-
-        pub fn compare_disjoint(a: *const @This(), b: *const @This()) std.math.Order {
-            if (a.start >= b.end()) {
-                return .gt;
-            } else if (b.start >= a.end()) {
-                return .lt;
-            } else {
-                return .eq;
-            }
-        }
     };
 }

src/util/rangemap.zig

@@ -1,450 +0,0 @@
-const std = @import("std");
-
-const btree = @import("btree.zig");
-
-const Range = @import("range.zig").Range;
-const Allocator = std.mem.Allocator;
-const BTree = btree.BTree;
-pub const Order = btree.Order;
-
-pub fn RangeMap(
-    comptime K: type,
-    comptime V: type,
-    comptime ops: struct {
-        deinit_fn: ?fn (*V) void = null,
-        merge_fn: ?fn (*const V, *const V) bool = null,
-    },
-) type {
-    return struct {
-        pub const Node = struct {
-            key: Range(K),
-            value: V,
-
-            pub fn len(self: *const @This()) K {
-                return self.key.len;
-            }
-        };
-
-        pub const WalkFn = fn (*const Node) void;
-
-        pub const Iterator = struct {
-            inner: Tree.Iterator,
-
-            pub fn next(self: *Iterator) ?*const Node {
-                if (self.inner.next()) |n| {
-                    return &n.key;
-                } else {
-                    return null;
-                }
-            }
-        };
-
-        pub const Tree = BTree(Node, compare_fn, deinit_node_fn);
-
-        pub const Error = error{
-            scalar_out_of_range,
-            range_out_of_bounds,
-        } || Tree.Error;
-
-        fn compare_fn(a: *const Node, b: *const Node) Order {
-            return Range(K).compare_disjoint(&a.key, &b.key);
-        }
-
-        fn deinit_node_fn(n: *Node) void {
-            if (comptime ops.deinit_fn) |f| {
-                f(&n.value);
-            }
-        }
-
-        btree: Tree,
-
-        pub fn init(gpa: Allocator) @This() {
-            return .{ .btree = Tree.init(gpa) };
-        }
-
-        pub fn deinit(self: *@This()) void {
-            self.btree.deinit();
-        }
-
-        /// Returns the value at a given scalar point, along with the full range it belongs to.
-        pub fn get_scalar(self: *const @This(), scalar: K) ?*Node {
-            return if (self.get_scalar_node(scalar)) |n| &n.key else null;
-        }
-
-        /// Same as `get_scalar()`, but returns the underlying BST node.
-        pub fn get_scalar_node(self: *const @This(), scalar: K) ?*Tree.Node {
-            return self.btree.search(scalar, struct {
-                fn call(n: *const Node, cx: K) Order {
-                    if (n.key.contains(cx)) {
-                        return .eq;
-                    } else if (cx < n.key.start) {
-                        return .gt;
-                    } else {
-                        return .lt;
-                    }
-                }
-            }.call);
-        }
-
-        /// Splits a given node at a scalar point inside its interval.
-        ///
-        /// The part of the interval before `at` is considered a "left" half, the remaining
-        /// part is considered a "right" half.
-        ///
-        /// # Note
-        ///
-        /// The "right" halve's value after the split is left uninitialized and it is up to the
-        /// caller to assign a proper value to it.
-        ///
-        /// # Errors
-        ///
-        /// * `scalar_out_of_range` if the given `at` value is not inside the node's interval.
-        pub fn split_node(
-            self: *@This(),
-            node: *Tree.Node,
-            at: K,
-        ) Error!?struct { *Tree.Node, *Tree.Node } {
-            if (!node.key.key.contains(at)) {
-                return error.scalar_out_of_range;
-            }
-
-            const start = node.key.key.start;
-            const end = node.key.key.end();
-
-            if (at == start or at == end - 1) {
-                // Nothing to split here
-                return null;
-            }
-
-            const value = node.key.value;
-
-            // Remove the node, don't drop the key
-            try self.btree.remove_node(node, false);
-
-            const lnode = try self.btree.insert(
-                .{ .key = .{ .start = start, .len = at - start }, .value = value },
-            );
-            const rnode = try self.btree.insert(
-                .{ .key = .{ .start = at, .len = end - at }, .value = undefined },
-            );
-
-            return .{ lnode, rnode };
-        }
-
-        /// Maps some range to a value. Returns an error if the requested range crosses another
-        /// mapped range.
-        pub fn insert(self: *@This(), start: K, len: K, value: V) Error!*Tree.Node {
-            try validate_range(start, len);
-
-            if (comptime ops.merge_fn) |merge_fn| {
-                const left: ?*Tree.Node = if (start > 0) self.get_scalar_node(start - 1) else null;
-                const right = self.get_scalar_node(start + len);
-
-                if (left) |l| {
-                    const l_start = l.key.key.start;
-
-                    if (merge_fn(&l.key.value, &value)) {
-                        if (right) |r| {
-                            if (merge_fn(&r.key.value, &value)) {
-                                l.key.key.len += len + r.key.key.len;
-                                try self.btree.remove_node(r, true);
-                                return self.get_scalar_node(l_start).?;
-                            }
-                        }
-
-                        l.key.key.len += len;
-                        return l;
-                    }
-                }
-
-                if (right) |r| {
-                    // Only right node to potentially merge with
-                    if (merge_fn(&r.key.value, &value)) {
-                        const r_len = r.key.key.len;
-                        try self.btree.remove_node(r, true);
-                        return self.btree.insert(.{
-                            .key = .{ .start = start, .len = len + r_len },
-                            .value = value,
-                        });
-                    }
-                }
-            }
-
-            return self.btree.insert(.{
-                .key = .{ .start = start, .len = len },
-                .value = value,
-            });
-        }
-
-        pub fn iterator(self: *@This()) Iterator {
-            return .{ .inner = self.btree.iterator() };
-        }
-
-        pub fn node_iterator(self: *@This()) Tree.Iterator {
-            return self.btree.iterator();
-        }
-
-        pub fn walk(self: *@This(), walk_fn: WalkFn) void {
-            self.btree.walk(walk_fn, struct {
-                fn call(n: *const Tree.Node, cx: WalkFn) void {
-                    cx(&n.key);
-                }
-            }.call);
-        }
-
-        fn validate_range(start: K, end: K) Error!void {
-            // Check for addition overflowing the K's bit size
-            if (std.math.add(K, start, end) == error.Overflow) {
-                return error.range_out_of_bounds;
-            }
-        }
-    };
-}
-
-test "Range map insertion" {
-    const Map = RangeMap(u32, []const u8, .{});
-    var map = Map.init(std.testing.allocator);
-    defer map.deinit();
-
-    _ = try map.insert(10, 10, "Range 2");
-    _ = try map.insert(0, 10, "Range 1");
-    _ = try map.insert(20, 10, "Range 3");
-
-    try std.testing.expectError(error.already_exists, map.insert(5, 10, "Invalid range"));
-
-    _ = try map.insert(1000, 10, "Range 4");
-}
-
-test "Range map merging insertion" {
-    const Map = RangeMap(u32, bool, .{
-        .merge_fn = struct {
-            fn call(lhs: *const bool, rhs: *const bool) bool {
-                return !lhs.* and !rhs.*;
-            }
-        }.call,
-    });
-    var map = Map.init(std.testing.allocator);
-    defer map.deinit();
-
-    // Should not merge
-    _ = try map.insert(10, 10, false);
-    _ = try map.insert(0, 10, true);
-
-    {
-        var it = map.iterator();
-        try std.testing.expectEqual(true, it.next().?.value);
-        try std.testing.expectEqual(false, it.next().?.value);
-        try std.testing.expectEqual(null, it.next());
-    }
-
-    // Merge left + inserted + right
-    _ = try map.insert(30, 10, false);
-    _ = try map.insert(20, 10, false);
-
-    {
-        var it = map.iterator();
-        const n0 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 0, .len = 10 }, n0.key);
-        try std.testing.expectEqual(true, n0.value);
-
-        const n1 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 10, .len = 30 }, n1.key);
-        try std.testing.expectEqual(false, n1.value);
-
-        try std.testing.expectEqual(null, it.next());
-    }
-
-    // Should not merge again
-    _ = try map.insert(40, 10, true);
-    _ = try map.insert(50, 10, false);
-
-    {
-        var it = map.iterator();
-        const n0 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 0, .len = 10 }, n0.key);
-        try std.testing.expectEqual(true, n0.value);
-
-        const n1 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 10, .len = 30 }, n1.key);
-        try std.testing.expectEqual(false, n1.value);
-
-        const n2 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 40, .len = 10 }, n2.key);
-        try std.testing.expectEqual(true, n2.value);
-
-        const n3 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 50, .len = 10 }, n3.key);
-        try std.testing.expectEqual(false, n3.value);
-
-        try std.testing.expectEqual(null, it.next());
-    }
-
-    // Should merge left + shouldn't merge right non-contiguous
-    _ = try map.insert(71, 9, false);
-    _ = try map.insert(60, 10, false);
-
-    {
-        var it = map.iterator();
-        const n0 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 0, .len = 10 }, n0.key);
-        try std.testing.expectEqual(true, n0.value);
-
-        const n1 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 10, .len = 30 }, n1.key);
-        try std.testing.expectEqual(false, n1.value);
-
-        const n2 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 40, .len = 10 }, n2.key);
-        try std.testing.expectEqual(true, n2.value);
-
-        const n3 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 50, .len = 20 }, n3.key);
-        try std.testing.expectEqual(false, n3.value);
-
-        const n4 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 71, .len = 9 }, n4.key);
-        try std.testing.expectEqual(false, n4.value);
-
-        try std.testing.expectEqual(null, it.next());
-    }
-
-    // Should merge left and right
-    _ = try map.insert(70, 1, false);
-
-    {
-        var it = map.iterator();
-        const n0 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 0, .len = 10 }, n0.key);
-        try std.testing.expectEqual(true, n0.value);
-
-        const n1 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 10, .len = 30 }, n1.key);
-        try std.testing.expectEqual(false, n1.value);
-
-        const n2 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 40, .len = 10 }, n2.key);
-        try std.testing.expectEqual(true, n2.value);
-
-        const n3 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 50, .len = 30 }, n3.key);
-        try std.testing.expectEqual(false, n3.value);
-
-        try std.testing.expectEqual(null, it.next());
-    }
-
-    // Should merge right
-    _ = try map.insert(110, 10, false);
-    _ = try map.insert(100, 10, false);
-
-    {
-        var it = map.iterator();
-        const n0 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 0, .len = 10 }, n0.key);
-        try std.testing.expectEqual(true, n0.value);
-
-        const n1 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 10, .len = 30 }, n1.key);
-        try std.testing.expectEqual(false, n1.value);
-
-        const n2 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 40, .len = 10 }, n2.key);
-        try std.testing.expectEqual(true, n2.value);
-
-        const n3 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 50, .len = 30 }, n3.key);
-        try std.testing.expectEqual(false, n3.value);
-
-        const n4 = it.next().?;
-        try std.testing.expectEqual(Range(u32){ .start = 100, .len = 20 }, n4.key);
-        try std.testing.expectEqual(false, n4.value);
-
-        try std.testing.expectEqual(null, it.next());
-    }
-}
-
-test "Range map get scalar" {
-    const Map = RangeMap(u32, []const u8, .{});
-    var map = Map.init(std.testing.allocator);
-    defer map.deinit();
-
-    _ = try map.insert(10, 10, "Range [10..20)");
-    _ = try map.insert(30, 10, "Range [30..40)");
-
-    {
-        const n = map.get_scalar(15).?;
-        try std.testing.expectEqual(10, n.key.start);
-        try std.testing.expectEqual(20, n.key.end());
-        try std.testing.expectEqualStrings("Range [10..20)", n.value);
-    }
-    {
-        const n = map.get_scalar(35).?;
-        try std.testing.expectEqual(30, n.key.start);
-        try std.testing.expectEqual(40, n.key.end());
-        try std.testing.expectEqualStrings("Range [30..40)", n.value);
-    }
-    {
-        const n = map.get_scalar(30).?;
-        try std.testing.expectEqual(30, n.key.start);
-        try std.testing.expectEqual(40, n.key.end());
-        try std.testing.expectEqualStrings("Range [30..40)", n.value);
-    }
-    try std.testing.expectEqual(null, map.get_scalar(20));
-    try std.testing.expectEqual(null, map.get_scalar(21));
-    try std.testing.expectEqual(null, map.get_scalar(9));
-    try std.testing.expectEqual(null, map.get_scalar(100));
-    try std.testing.expectEqual(null, map.get_scalar(40));
-    try std.testing.expectEqual(null, map.get_scalar(41));
-}
-
-test "Range map split" {
-    const Map = RangeMap(u32, []const u8, .{});
-    var map = Map.init(std.testing.allocator);
-    defer map.deinit();
-
-    _ = try map.insert(0x1000, 0x1000, "Range [0x1000..0x2000)");
-
-    const node = map.get_scalar_node(0x1000).?;
-    const lnode, const rnode = (try map.split_node(node, 0x1200)).?;
-
-    lnode.key.value = "Left";
-    rnode.key.value = "Right";
-
-    {
-        const n = map.get_scalar(0x1100).?;
-        try std.testing.expectEqual(0x1000, n.key.start);
-        try std.testing.expectEqual(0x200, n.key.len);
-        try std.testing.expectEqualStrings("Left", n.value);
-    }
-    {
-        const n = map.get_scalar(0x1300).?;
-        try std.testing.expectEqual(0x1200, n.key.start);
-        try std.testing.expectEqual(0xE00, n.key.len);
-        try std.testing.expectEqualStrings("Right", n.value);
-    }
-}
-
-test "Range map iterator" {
-    const Map = RangeMap(u32, []const u8, .{});
-    var map = Map.init(std.testing.allocator);
-    defer map.deinit();
-
-    _ = try map.insert(0x1000, 0x1000, "Range [0x1000..0x2000)");
-    _ = try map.insert(0x2000, 0x1000, "Range [0x2000..0x3000)");
-    _ = try map.insert(0x4000, 0x1000, "Range [0x4000..0x5000)");
-    _ = try map.insert(0x3000, 0x1000, "Range [0x3000..0x4000)");
-
-    var it = map.iterator();
-    try std.testing.expectEqualStrings("Range [0x1000..0x2000)", it.next().?.value);
-    try std.testing.expectEqualStrings("Range [0x2000..0x3000)", it.next().?.value);
-    try std.testing.expectEqualStrings("Range [0x3000..0x4000)", it.next().?.value);
-    try std.testing.expectEqualStrings("Range [0x4000..0x5000)", it.next().?.value);
-    try std.testing.expectEqual(null, it.next());
-}
-
-test "Range map should disallow overflowing ranges" {
-    const Map = RangeMap(u32, bool, .{});
-    var map = Map.init(std.testing.allocator);
-    defer map.deinit();
-
-    try std.testing.expectError(error.range_out_of_bounds, map.insert(0xF0000000, 0x20000000, false));
-}

user/aarch64.ld

@@ -1,27 +0,0 @@
-SECTIONS {
-    . = 0x200000;
-
-    .text : {
-        *(.text.entry*);
-        *(.text*)
-    }
-
-    .rodata : ALIGN(4K) {
-        *(.rodata*)
-    }
-
-    .eh_frame_hdr : {
-        *(.eh_frame_hdr*)
-    }
-    .eh_frame : {
-        *(.eh_frame*)
-    }
-
-    .data : ALIGN(4K) {
-        *(.data*)
-    }
-
-    .bss : ALIGN(4K) {
-        *(.bss*)
-    }
-}

user/arch.zig

@@ -1,9 +0,0 @@
-const builtin = @import("builtin");
-
-const impl = switch (builtin.cpu.arch) {
-    .riscv64 => @import("arch/riscv64.zig"),
-    .aarch64 => @import("arch/aarch64.zig"),
-    else => @compileError("Unsupported architecture"),
-};
-
-pub const syscall = impl.syscall;

user/arch/aarch64.zig

@@ -1,55 +0,0 @@
-const abi = @import("abi");
-
-pub const syscall = struct {
-    pub fn send(handle: u32, msg: *const [5]usize) usize {
-        return asm volatile ("svc #0"
-            : [result] "={x0}" (-> usize),
-            : [a0] "{x0}" (handle),
-              [a1] "{x1}" (msg[0]),
-              [a2] "{x2}" (msg[1]),
-              [a3] "{x3}" (msg[2]),
-              [a4] "{x4}" (msg[3]),
-              [a5] "{x5}" (msg[4]),
-              [func] "{x8}" (@intFromEnum(abi.SyscallNumber.SYS_send)),
-            : "memory"
-        );
-    }
-
-    pub fn sendrecv(handle: u32, msg: *const[5]usize, buffer: *[5]usize) usize {
-        return asm volatile (
-            \\ svc #0
-            \\ stp x1, x2, [%[buf], #16 * 0]
-            \\ stp x3, x4, [%[buf], #16 * 1]
-            \\ str x5,     [%[buf], #16 * 2]
-            : [result] "={x0}" (-> usize),
-            : [a0] "{x0}" (handle),
-              [a1] "{x1}" (msg[0]),
-              [a2] "{x2}" (msg[1]),
-              [a3] "{x3}" (msg[2]),
-              [a4] "{x4}" (msg[3]),
-              [a5] "{x5}" (msg[4]),
-              [func] "{x8}" (@intFromEnum(abi.SyscallNumber.SYS_sendrecv)),
-              [buf] "r" (buffer),
-            : "memory"
-        );
-    }
-
-    // pub fn syscall1(func: abi.SyscallNumber, arg0: usize) usize {
-    //     return asm volatile ("svc #0"
-    //         : [result] "={x0}" (-> usize),
-    //         : [arg0] "{x0}" (arg0),
-    //           [func] "{x8}" (@intFromEnum(func)),
-    //         : "memory"
-    //     );
-    // }
-
-    // pub fn syscall2(func: abi.SyscallNumber, arg0: usize, arg1: usize) usize {
-    //     return asm volatile ("svc #0"
-    //         : [result] "={x0}" (-> usize),
-    //         : [arg0] "{x0}" (arg0),
-    //           [arg1] "{x1}" (arg1),
-    //           [func] "{x8}" (@intFromEnum(func)),
-    //         : "memory"
-    //     );
-    // }
-};

user/arch/riscv64.zig

@@ -1,22 +0,0 @@
-const abi = @import("abi");
-
-pub const syscall = struct {
-    pub fn syscall1(func: abi.SyscallNumber, arg0: usize) usize {
-        return asm volatile ("ecall"
-            : [result] "={a0}" (-> usize),
-            : [func] "{a0}" (@intFromEnum(func)),
-              [arg0] "{a1}" (arg0),
-            : "memory"
-        );
-    }
-
-    pub fn syscall2(func: abi.SyscallNumber, arg0: usize, arg1: usize) usize {
-        return asm volatile ("ecall"
-            : [result] "={a0}" (-> usize),
-            : [func] "{a0}" (@intFromEnum(func)),
-              [arg0] "{a1}" (arg0),
-              [arg1] "{a2}" (arg1),
-            : "memory"
-        );
-    }
-};

user/log.zig

@@ -1,28 +0,0 @@
-const std = @import("std");
-const syscall = @import("syscall.zig");
-
-pub const BUFFER_SIZE: usize = 512;
-
-pub const Writer = struct {
-    buffer: [BUFFER_SIZE]u8 = undefined,
-    position: usize = 0,
-
-    fn write(self: *Writer, bytes: []const u8) error{}!usize {
-        const amount = @min(BUFFER_SIZE - self.position, bytes.len);
-        if (amount != 0) {
-            @memcpy(self.buffer[self.position .. self.position + amount], bytes[0..amount]);
-            self.position += amount;
-        }
-        return amount;
-    }
-};
-
-pub fn println(comptime format: []const u8, args: anytype) void {
-    const W = std.io.GenericWriter(*Writer, error{}, Writer.write);
-    var context = Writer{};
-    var w = W{ .context = &context };
-    w.print(format, args) catch return;
-    if (context.position != 0) {
-        syscall.debug_write(context.buffer[0..context.position]);
-    }
-}

user/main.zig

@@ -1,58 +0,0 @@
-pub const arch = @import("arch.zig");
-pub const syscall = @import("syscall.zig");
-pub const log = @import("log.zig");
-const abi = @import("abi");
-
-const Handle = abi.Handle;
-
-fn debug_write(handle: Handle, message: []const u8) void {
-    _ = syscall.send(handle, &.{
-        @intFromPtr(message.ptr),
-        message.len,
-        0,
-        0,
-        0,
-    });
-}
-
-fn exit_process(handle: Handle, code: u32) noreturn {
-    _ = syscall.send(handle, &.{
-        @intFromEnum(abi.ProcessObjectAction.ZO_process_exit),
-        code,
-        0,
-        0,
-        0,
-    });
-    unreachable;
-}
-
-fn allocate_memory(handle: Handle, count: usize) u64 {
-    var output: [5]usize = undefined;
-    // TODO error code
-    _ = syscall.sendrecv(
-        handle,
-        &.{
-            @intFromEnum(abi.PhysicalMemoryObjectAction.ZO_physical_memory_allocate),
-            count,
-            0,
-            0,
-            0,
-        },
-        &output,
-    );
-    return output[0];
-}
-
-export fn _start(arg: usize) linksection(".text.entry") callconv(.C) noreturn {
-    // TODO make the kernel provide those dynamically somehow
-    const SELF_PROCESS_HANDLE: Handle = @enumFromInt(1);
-    const PHYSICAL_MEMORY_HANDLE: Handle = @enumFromInt(2);
-    const DEBUG_HANDLE: Handle = @enumFromInt(3);
-
-    _ = arg;
-    const mem = allocate_memory(PHYSICAL_MEMORY_HANDLE, 8);
-    _ = mem;
-
-    debug_write(DEBUG_HANDLE, "Hello!!!");
-    exit_process(SELF_PROCESS_HANDLE, 4321);
-}

user/riscv64.ld

@@ -1,20 +0,0 @@
-SECTIONS {
-    . = 0x200000;
-
-    .text : {
-        *(.text.entry*);
-        *(.text*)
-    }
-
-    .rodata : ALIGN(4K) {
-        *(.rodata*)
-    }
-
-    .data : ALIGN(4K) {
-        *(.data*)
-    }
-
-    .bss : ALIGN(4K) {
-        *(.bss*)
-    }
-}

user/syscall.zig

@@ -1,25 +0,0 @@
-const arch = @import("arch.zig");
-const abi = @import("abi");
-
-const sc = arch.syscall;
-
-pub inline fn send(object: abi.Handle, msg: *const [5]usize) usize {
-    return sc.send(@intFromEnum(object), msg);
-}
-
-pub inline fn recv(object: abi.Handle, buffer: *[5]usize) usize {
-    return sc.recv(@intFromEnum(object), buffer);
-}
-
-pub inline fn sendrecv(object: abi.Handle, msg: *const [5]usize, buffer: *[5]usize) usize {
-    return sc.sendrecv(@intFromEnum(object), msg, buffer);
-}
-
-// pub fn exit(code: u32) noreturn {
-//     _ = sc.syscall1(SC.SYS_exit, code);
-//     unreachable;
-// }
-//
-// pub fn debug_write(text: []const u8) void {
-//     _ = sc.syscall2(SC.SYS_debug_write, @intFromPtr(text.ptr), text.len);
-// }