refactor(userspace): split syscall stubs into arch-agnostic API + arch/riscv backend

crates/userspace/src/arch/mod.rs

@@ -0,0 +1,14 @@
+#[cfg(target_arch = "riscv64")]
+mod riscv;
+#[cfg(target_arch = "riscv64")]
+pub use riscv::*;
+
+#[cfg(target_arch = "aarch64")]
+mod arm;
+#[cfg(target_arch = "aarch64")]
+pub use arm::*;
+
+#[cfg(target_arch = "x86_64")]
+mod x86;
+#[cfg(target_arch = "x86_64")]
+pub use x86::*;

crates/userspace/src/arch/riscv.rs

@@ -0,0 +1,75 @@
+#[inline(always)]
+pub fn syscall0(nr: usize) -> usize {
+    let ret: usize;
+    unsafe {
+        core::arch::asm!(
+            "ecall",
+            in("a7") nr,
+            lateout("a0") ret,
+        );
+    }
+    ret
+}
+
+#[inline(always)]
+pub fn syscall1(nr: usize, a0: usize) -> usize {
+    let ret: usize;
+    unsafe {
+        core::arch::asm!(
+            "ecall",
+            in("a7") nr,
+            inlateout("a0") a0 => ret,
+        );
+    }
+    ret
+}
+
+#[inline(always)]
+pub fn syscall2(nr: usize, a0: usize, a1: usize) -> usize {
+    let ret: usize;
+    unsafe {
+        core::arch::asm!(
+            "ecall",
+            in("a7") nr,
+            inlateout("a0") a0 => ret,
+            in("a1") a1,
+        );
+    }
+    ret
+}
+
+#[inline(always)]
+pub fn syscall5(nr: usize, a0: usize, a1: usize, a2: usize, a3: usize, a4: usize) -> usize {
+    let ret: usize;
+    unsafe {
+        core::arch::asm!(
+            "ecall",
+            in("a7") nr,
+            inlateout("a0") a0 => ret,
+            in("a1") a1,
+            in("a2") a2,
+            in("a3") a3,
+            in("a4") a4,
+        );
+    }
+    ret
+}
+
+#[inline(always)]
+pub fn syscall_receive(nr: usize, a0: usize) -> (usize, usize, usize, usize) {
+    let r0: usize;
+    let r1: usize;
+    let r2: usize;
+    let r3: usize;
+    unsafe {
+        core::arch::asm!(
+            "ecall",
+            in("a7") nr,
+            inlateout("a0") a0 => r0,
+            lateout("a1") r1,
+            lateout("a2") r2,
+            lateout("a3") r3,
+        );
+    }
+    (r0, r1, r2, r3)
+}