rv64: implement signal handling

kernel/src/arch/riscv64/exception.rs

@@ -1,11 +1,6 @@
 use core::arch::global_asm;
 
-use abi::{
-    arch::SavedFrame,
-    primitive_enum,
-    process::{ExitCode, Signal},
-    SyscallFunction,
-};
+use abi::{arch::SavedFrame, primitive_enum, process::Signal, SyscallFunction};
 use kernel_arch::task::TaskFrame;
 use libk::{device::external_interrupt_controller, task::thread::Thread};
 use tock_registers::interfaces::ReadWriteable;
@@ -17,7 +12,7 @@ use crate::syscall;
 use super::{smp, timer};
 
 primitive_enum! {
-    pub enum Cause: u64 {
+    pub enum Cause: usize {
         MisalignedInstruction = 0,
         InstructionAccessFault = 1,
         IllegalInstruction = 2,
@@ -39,18 +34,18 @@ primitive_enum! {
 #[repr(C)]
 pub struct TrapFrame {
     // General-purpose
-    pub ra: u64,
-    pub gp: u64,
-    pub tn: [u64; 7],
-    pub sn: [u64; 12],
+    pub ra: usize,
+    pub gp: usize,
+    pub tn: [usize; 7],
+    pub sn: [usize; 12],
     pub an: [usize; 8],
     // Special
-    pub sp: u64,
-    pub sstatus: u64,
-    pub sepc: u64,
-    pub stval: u64,
-    pub scause: u64,
-    pub tp: u64,
+    pub sp: usize,
+    pub sstatus: usize,
+    pub sepc: usize,
+    pub stval: usize,
+    pub scause: usize,
+    pub tp: usize,
 }
 
 pub fn init_smode_exceptions() {
@@ -82,7 +77,10 @@ unsafe fn umode_exception_handler(frame: &mut TrapFrame) {
         Some(Cause::EcallUmode) => {
             let func = frame.an[0];
             if func == usize::from(SyscallFunction::ExitSignal) {
-                todo!()
+                unsafe {
+                    syscall::handle_signal_exit(frame);
+                }
+                return;
             }
 
             let args = &frame.an[1..];
@@ -112,7 +110,7 @@ unsafe fn umode_exception_handler(frame: &mut TrapFrame) {
         log::warn!("Of process {} ({:?})", process.id, process.name);
 
         if dump_tval {
-            let translation = process.space().translate(frame.stval as usize).ok();
+            let translation = process.space().translate(frame.stval).ok();
 
             if let Some(physical) = translation {
                 log::warn!(" * tval translates to {physical:#x}");
@@ -120,8 +118,6 @@ unsafe fn umode_exception_handler(frame: &mut TrapFrame) {
                 log::warn!(" * tval does not translate");
             }
         }
-
-        thread.exit_process(ExitCode::BySignal(Ok(Signal::MemoryAccessViolation)));
     }
 }
 
@@ -146,7 +142,7 @@ unsafe fn smode_exception_handler(frame: &mut TrapFrame) {
                 .and_then(|t| t.try_get_process())
                 .map(|p| p.space())
             {
-                space.translate(frame.stval as usize).ok()
+                space.translate(frame.stval).ok()
             } else {
                 None
             };
@@ -206,39 +202,53 @@ unsafe extern "C" fn smode_general_trap_handler(frame: *mut TrapFrame) {
 
 impl TaskFrame for TrapFrame {
     fn store(&self) -> SavedFrame {
-        todo!()
+        SavedFrame {
+            ra: self.ra,
+            gp: self.gp,
+            tn: self.tn,
+            sn: self.sn,
+            an: self.an,
+
+            sp: self.sp,
+            ip: self.sepc,
+            tp: self.tp,
+        }
     }
 
     fn restore(&mut self, saved: &SavedFrame) {
-        let _ = saved;
-        todo!()
+        self.ra = saved.ra;
+        self.gp = saved.gp;
+        self.tn = saved.tn;
+        self.sn = saved.sn;
+        self.an = saved.an;
+
+        self.sp = saved.sp;
+        self.sepc = saved.ip;
+        self.tp = saved.tp;
     }
 
     fn user_sp(&self) -> usize {
-        todo!()
+        self.sp
     }
 
     fn user_ip(&self) -> usize {
-        todo!()
+        self.sepc
     }
 
     fn argument(&self) -> u64 {
-        todo!()
+        self.an[0] as u64
     }
 
     fn set_user_sp(&mut self, value: usize) {
-        let _ = value;
-        todo!()
+        self.sp = value;
     }
 
     fn set_user_ip(&mut self, value: usize) {
-        let _ = value;
-        todo!()
+        self.sepc = value;
     }
 
     fn set_argument(&mut self, value: u64) {
-        let _ = value;
-        todo!()
+        self.an[0] = value as usize;
     }
 
     fn set_single_step(&mut self, step: bool) {
@@ -247,8 +257,7 @@ impl TaskFrame for TrapFrame {
     }
 
     fn set_return_value(&mut self, value: u64) {
-        let _ = value;
-        todo!()
+        self.an[0] = value as usize;
     }
 }
 

lib/abi/src/arch/riscv64.rs

@@ -5,7 +5,18 @@ use super::FrameOps;
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[derive(Clone, Debug, Default)]
 #[repr(C)]
-pub struct SavedFrame {}
+pub struct SavedFrame {
+    // General-purpose
+    pub ra: usize,
+    pub gp: usize,
+    pub tn: [usize; 7],
+    pub sn: [usize; 12],
+    pub an: [usize; 8],
+    // Special
+    pub sp: usize,
+    pub ip: usize,
+    pub tp: usize,
+}
 
 impl FrameOps for SavedFrame {
     fn set_user_ip(&mut self, value: usize) {