Add a way to handle illegal system call and segmentation faults in

signal handlers

include/sys/amd64/syscall.h

@@ -7,5 +7,5 @@ struct cpu_context;
 extern uint64_t syscall_count;
 
 void amd64_syscall_init(void);
-extern void amd64_syscall_iretq(struct cpu_context *ctx);
+__attribute__((noreturn)) void amd64_syscall_iretq(struct cpu_context *ctx);
 __attribute__((noreturn)) void amd64_syscall_yield_stopped(void);

include/sys/signum.h

@@ -1,12 +1,10 @@
 #pragma once
 
 #define SIGINT      2
-#define SIGQUIT     3
-#define SIGILL      4
 #define SIGABRT     6
-#define SIGFPE      8
 #define SIGKILL     9
 #define SIGSEGV     11
+#define SIGSYS      12
 #define SIGTERM     15
 
 #define SIGUSR1     16

include/sys/types.h

@@ -1,5 +1,13 @@
 #pragma once
+#if defined(__KERNEL__)
 #include <stdint.h>
+#else
+typedef unsigned int uint32_t;
+typedef int int32_t;
+typedef unsigned long uint64_t;
+typedef long int64_t;
+typedef int sig_atomic_t;
+#endif
 
 #ifndef NULL
 #define NULL ((void *) 0)

sys/amd64/hw/pfault.c

@@ -1,7 +1,9 @@
 #include "sys/amd64/mm/map.h"
+#include "sys/amd64/syscall.h"
 #include "sys/amd64/cpu.h"
 #include "sys/assert.h"
 #include "sys/thread.h"
+#include "sys/signum.h"
 #include "sys/debug.h"
 
 extern void amd64_syscall_yield_stopped();
@@ -23,6 +25,7 @@ int amd64_pfault(uintptr_t cr2) {
         thr->pid);
 
     kerror("CR2 = %p\n", cr2);
+    kerror("RIP = %p\n", ctx->rip);
 
     // Dump registers
     cpu_print_context(DEBUG_ERROR, ctx);
@@ -35,9 +38,25 @@ int amd64_pfault(uintptr_t cr2) {
     // because they're presumably fucked up by error code
     // push
 
-    thr->flags |= THREAD_STOPPED;
-    amd64_syscall_yield_stopped();
-    return -1;
+    // The whole thread context is on the stack
+
+    if (thr->pid > 0) {
+        thread_signal(thr, SIGSEGV);
+
+        // Suicide signal, just hang on and wait
+        // until scheduler decides it's our time
+        while (thr->sigq) {
+            asm volatile ("sti; hlt; cli");
+        }
+
+        amd64_syscall_iretq(ctx);
+    } else {
+        panic("Segmentation fault happened in kernel thread\n");
+    }
+
+    //thr->flags |= THREAD_STOPPED;
+    //amd64_syscall_yield_stopped();
+    //return -1;
 }
 
 void amd64_pfault_kernel(uintptr_t rip, uintptr_t cr2) {

sys/amd64/hw/pfault_s.S

@@ -14,9 +14,12 @@ amd64_exc_isr_14:
     // rip
     swapgs_if_needed
 
+    // Fuck error code
+    addq $8, %rsp
+
     pushq %rax
     movq $(1 << 63), %rax
-    testq %rax, 16(%rsp)
+    testq %rax, 8(%rsp)
     jnz _pfault_kernel
     popq %rax
 
@@ -38,16 +41,7 @@ amd64_exc_isr_14:
 
     movq %cr2, %rdi
     call amd64_pfault
-
-    // If fault handler returned zero, it means next task is selected
-    // and should be run
-    test %rax, %rax
-    jnz 1f
-
-    // Ok, continue
-
-
-    // Fail
+    // Failed to handle the fault
 1:
     cli
     hlt

sys/amd64/sys_proc.c

@@ -2,6 +2,7 @@
 #include "sys/amd64/syscall.h"
 #include "sys/amd64/cpu.h"
 #include "sys/assert.h"
+#include "sys/signum.h"
 #include "sys/sched.h"
 #include "sys/thread.h"
 #include "sys/debug.h"
@@ -138,3 +139,19 @@ gid_t sys_getgid(void) {
     _assert(thr);
     return thr->ioctx.gid;
 }
+
+int sys_unknown(int no) {
+    asm volatile ("cli");
+    struct thread *thr = get_cpu()->thread;
+    _assert(thr);
+
+    thread_signal(thr, SIGSYS);
+
+    // Suicide signal, just hang on and wait
+    // until scheduler decides it's our time
+    while (thr->sigq) {
+        asm volatile ("sti; hlt; cli");
+    }
+
+    return -EINVAL;
+}

sys/amd64/syscall.c

@@ -53,6 +53,5 @@ const void *amd64_syscall_jmp_table[256] = {
 
     // Memory
     [SYSCALL_NR_BRK] = sys_brk,
-    NULL
 };
 

sys/amd64/syscall_s.S

@@ -76,15 +76,15 @@ amd64_syscall_entry:
     movq %r10, %rcx
     incq syscall_count(%rip)
     leaq amd64_syscall_jmp_table(%rip), %r10
-    movq (%r10, %rax, 8), %rax
-    test %rax, %rax
+    movq (%r10, %rax, 8), %r10
+    test %r10, %r10
     jz 1f
     sti
-    call *%rax
+    call *%r10
     jmp 2f
 1:
-    // -EINVAL
-    mov $-22, %rax
+    movq %rax, %rdi
+    call sys_unknown
 2:
     //movq %rax, %r9
     //call amd64_syscall

sys/vfs/vfs.c

@@ -307,7 +307,6 @@ static int vfs_find_internal(struct vfs_ioctx *ctx, struct vnode *at, const char
         break;
     }
 
-    // TODO: lookup_or_load
     if ((err = vfs_lookup_or_load(at, name, &node)) != 0) {
         kdebug("miss %s in %s\n", name, at->name);
         return err;