From 6a42bb3b4a46fd24687fbf24a4015a787127adde Mon Sep 17 00:00:00 2001
From: Zejun Zhao <jelly.zhao.42@gmail.com>
Date: Fri, 26 Sep 2025 13:28:12 +0800
Subject: [PATCH] Make syscall restart mechanism work across all architectures

---
 kernel/src/arch/loongarch/cpu.rs |  4 ----
 kernel/src/arch/riscv/cpu.rs     |  4 ----
 kernel/src/arch/x86/cpu.rs       |  4 ----
 kernel/src/cpu.rs                |  3 ---
 kernel/src/process/signal/mod.rs | 10 +++++-----
 kernel/src/thread/task.rs        |  6 +++---
 6 files changed, 8 insertions(+), 23 deletions(-)

diff --git a/kernel/src/arch/loongarch/cpu.rs b/kernel/src/arch/loongarch/cpu.rs
index a08984f55..a6c5a6121 100644
--- a/kernel/src/arch/loongarch/cpu.rs
+++ b/kernel/src/arch/loongarch/cpu.rs
@@ -17,10 +17,6 @@ impl LinuxAbi for UserContext {
         self.a7()
     }
 
-    fn set_syscall_num(&mut self, num: usize) {
-        self.set_a7(num);
-    }
-
     fn syscall_ret(&self) -> usize {
         self.a0()
     }
diff --git a/kernel/src/arch/riscv/cpu.rs b/kernel/src/arch/riscv/cpu.rs
index 707c1a69e..7b5cab29d 100644
--- a/kernel/src/arch/riscv/cpu.rs
+++ b/kernel/src/arch/riscv/cpu.rs
@@ -17,10 +17,6 @@ impl LinuxAbi for UserContext {
         self.a7()
     }
 
-    fn set_syscall_num(&mut self, num: usize) {
-        self.set_a7(num);
-    }
-
     fn syscall_ret(&self) -> usize {
         self.a0()
     }
diff --git a/kernel/src/arch/x86/cpu.rs b/kernel/src/arch/x86/cpu.rs
index 9bae0dd16..d28620730 100644
--- a/kernel/src/arch/x86/cpu.rs
+++ b/kernel/src/arch/x86/cpu.rs
@@ -29,10 +29,6 @@ impl LinuxAbi for UserContext {
         self.rax()
     }
 
-    fn set_syscall_num(&mut self, num: usize) {
-        self.set_rax(num);
-    }
-
     fn set_syscall_ret(&mut self, ret: usize) {
         self.set_rax(ret);
     }
diff --git a/kernel/src/cpu.rs b/kernel/src/cpu.rs
index 72597874b..c872ac5df 100644
--- a/kernel/src/cpu.rs
+++ b/kernel/src/cpu.rs
@@ -8,9 +8,6 @@ pub trait LinuxAbi {
     /// Gets the return value of the system call.
     fn syscall_ret(&self) -> usize;
 
-    /// Sets the system call number.
-    fn set_syscall_num(&mut self, num: usize);
-
     /// Sets the return value of the system call.
     fn set_syscall_ret(&mut self, ret: usize);
 
diff --git a/kernel/src/process/signal/mod.rs b/kernel/src/process/signal/mod.rs
index 91c9022cc..8261ab151 100644
--- a/kernel/src/process/signal/mod.rs
+++ b/kernel/src/process/signal/mod.rs
@@ -49,14 +49,14 @@ pub trait SignalContext {
 pub fn handle_pending_signal(
     user_ctx: &mut UserContext,
     ctx: &Context,
-    syscall_number: Option<usize>,
+    pre_syscall_ret: Option<usize>,
 ) {
-    let syscall_restart = if let Some(syscall_number) = syscall_number
+    let syscall_restart = if let Some(pre_syscall_ret) = pre_syscall_ret
         && user_ctx.syscall_ret() == -(Errno::ERESTARTSYS as i32) as usize
     {
         // We should never return `ERESTARTSYS` to the userspace.
         user_ctx.set_syscall_ret(-(Errno::EINTR as i32) as usize);
-        Some(syscall_number)
+        Some(pre_syscall_ret)
     } else {
         None
     };
@@ -90,7 +90,7 @@ pub fn handle_pending_signal(
             restorer_addr,
             mask,
         } => {
-            if let Some(syscall_number) = syscall_restart
+            if let Some(pre_syscall_ret) = syscall_restart
                 && flags.contains(SigActionFlags::SA_RESTART)
             {
                 #[cfg(target_arch = "x86_64")]
@@ -100,7 +100,7 @@ pub fn handle_pending_signal(
                 #[cfg(target_arch = "loongarch64")]
                 const SYSCALL_INSTR_LEN: usize = 4; // syscall
 
-                user_ctx.set_syscall_num(syscall_number);
+                user_ctx.set_syscall_ret(pre_syscall_ret);
                 user_ctx
                     .set_instruction_pointer(user_ctx.instruction_pointer() - SYSCALL_INSTR_LEN);
             }
diff --git a/kernel/src/thread/task.rs b/kernel/src/thread/task.rs
index ea9e610b8..72e64a5b6 100644
--- a/kernel/src/thread/task.rs
+++ b/kernel/src/thread/task.rs
@@ -83,14 +83,14 @@ pub fn create_new_user_task(
 
             // Handle user events
             let user_ctx = user_mode.context_mut();
-            let mut syscall_number = None;
+            let mut pre_syscall_ret = None;
             match return_reason {
                 ReturnReason::UserException => {
                     let exception = user_ctx.take_exception().unwrap();
                     handle_exception(&ctx, user_ctx, exception)
                 }
                 ReturnReason::UserSyscall => {
-                    syscall_number = Some(user_ctx.syscall_num());
+                    pre_syscall_ret = Some(user_ctx.syscall_ret());
                     handle_syscall(&ctx, user_ctx);
                 }
                 ReturnReason::KernelEvent => {}
@@ -102,7 +102,7 @@ pub fn create_new_user_task(
             }
 
             // Handle signals
-            handle_pending_signal(user_ctx, &ctx, syscall_number);
+            handle_pending_signal(user_ctx, &ctx, pre_syscall_ret);
 
             // Handle signals while the thread is stopped
             // FIXME: Currently, we handle all signals when the process is stopped.