RISC-V unwinder support

src/unwinder/arch/mod.rs

@@ -2,3 +2,8 @@
 mod x86_64;
 #[cfg(target_arch = "x86_64")]
 pub use x86_64::*;
+
+#[cfg(target_arch = "riscv64")]
+mod riscv64;
+#[cfg(target_arch = "riscv64")]
+pub use riscv64::*;

src/unwinder/arch/riscv64.rs

@@ -0,0 +1,195 @@
+use core::fmt;
+use core::ops;
+use gimli::{Register, RiscV};
+
+#[repr(C)]
+#[derive(Clone, Default)]
+pub struct Context {
+    pub gp: [usize; 32],
+    pub fp: [usize; 32],
+}
+
+impl fmt::Debug for Context {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut fmt = fmt.debug_struct("Context");
+        for i in 0..=31 {
+            fmt.field(RiscV::register_name(Register(i as _)).unwrap(), &self.gp[i]);
+        }
+        for i in 0..=31 {
+            fmt.field(
+                RiscV::register_name(Register((i + 32) as _)).unwrap(),
+                &self.fp[i],
+            );
+        }
+        fmt.finish()
+    }
+}
+
+impl ops::Index<Register> for Context {
+    type Output = usize;
+
+    fn index(&self, reg: Register) -> &usize {
+        match reg {
+            Register(0..=31) => &self.gp[reg.0 as usize],
+            Register(32..=63) => &self.fp[(reg.0 - 32) as usize],
+            _ => unimplemented!(),
+        }
+    }
+}
+
+impl ops::IndexMut<gimli::Register> for Context {
+    fn index_mut(&mut self, reg: Register) -> &mut usize {
+        match reg {
+            Register(0..=31) => &mut self.gp[reg.0 as usize],
+            Register(32..=63) => &mut self.fp[(reg.0 - 32) as usize],
+            _ => unimplemented!(),
+        }
+    }
+}
+
+macro_rules! code {
+    (save_gp) => {
+        "
+        sd x0, 0x00(a0)
+        sd ra, 0x08(a0)
+        sd sp, 0x10(a0)
+        sd gp, 0x18(a0)
+        sd tp, 0x20(a0)
+        sd s0, 0x40(a0)
+        sd s1, 0x48(a0)
+        sd s2, 0x90(a0)
+        sd s3, 0x98(a0)
+        sd s4, 0xA0(a0)
+        sd s5, 0xA8(a0)
+        sd s6, 0xB0(a0)
+        sd s7, 0xB8(a0)
+        sd s8, 0xC0(a0)
+        sd s9, 0xC8(a0)
+        sd s10, 0xD0(a0)
+        sd s11, 0xD8(a0)
+        "
+    };
+    (save_fp) => {
+        "
+        fsd fs0, 0x140(a0)
+        fsd fs1, 0x148(a0)
+        fsd fs2, 0x190(a0)
+        fsd fs3, 0x198(a0)
+        fsd fs4, 0x1A0(a0)
+        fsd fs5, 0x1A8(a0)
+        fsd fs6, 0x1B0(a0)
+        fsd fs7, 0x1B8(a0)
+        fsd fs8, 0x1C0(a0)
+        fsd fs9, 0x1C8(a0)
+        fsd fs10, 0x1D0(a0)
+        fsd fs11, 0x1D8(a0)
+        "
+    };
+    (restore_gp) => {
+        "
+        ld ra, 0x08(a0)
+        ld sp, 0x10(a0)
+        ld gp, 0x18(a0)
+        ld tp, 0x20(a0)
+        ld t0, 0x28(a0)
+        ld t1, 0x30(a0)
+        ld t2, 0x38(a0)
+        ld s0, 0x40(a0)
+        ld s1, 0x48(a0)
+        ld a1, 0x58(a0)
+        ld a2, 0x60(a0)
+        ld a3, 0x68(a0)
+        ld a4, 0x70(a0)
+        ld a5, 0x78(a0)
+        ld a6, 0x80(a0)
+        ld a7, 0x88(a0)
+        ld s2, 0x90(a0)
+        ld s3, 0x98(a0)
+        ld s4, 0xA0(a0)
+        ld s5, 0xA8(a0)
+        ld s6, 0xB0(a0)
+        ld s7, 0xB8(a0)
+        ld s8, 0xC0(a0)
+        ld s9, 0xC8(a0)
+        ld s10, 0xD0(a0)
+        ld s11, 0xD8(a0)
+        ld t3, 0xE0(a0)
+        ld t4, 0xE8(a0)
+        ld t5, 0xF0(a0)
+        ld t6, 0xF8(a0)
+        "
+    };
+    (restore_fp) => {
+        "
+        fld ft0, 0x100(a0)
+        fld ft1, 0x108(a0)
+        fld ft2, 0x110(a0)
+        fld ft3, 0x118(a0)
+        fld ft4, 0x120(a0)
+        fld ft5, 0x128(a0)
+        fld ft6, 0x130(a0)
+        fld ft7, 0x138(a0)
+        fld fs0, 0x140(a0)
+        fld fs1, 0x148(a0)
+        fld fa0, 0x150(a0)
+        fld fa1, 0x158(a0)
+        fld fa2, 0x160(a0)
+        fld fa3, 0x168(a0)
+        fld fa4, 0x170(a0)
+        fld fa5, 0x178(a0)
+        fld fa6, 0x180(a0)
+        fld fa7, 0x188(a0)
+        fld fs2, 0x190(a0)
+        fld fs3, 0x198(a0)
+        fld fs4, 0x1A0(a0)
+        fld fs5, 0x1A8(a0)
+        fld fs6, 0x1B0(a0)
+        fld fs7, 0x1B8(a0)
+        fld fs8, 0x1C0(a0)
+        fld fs9, 0x1C8(a0)
+        fld fs10, 0x1D0(a0)
+        fld fs11, 0x1D8(a0)
+        fld ft8, 0x1E0(a0)
+        fld ft9, 0x1E8(a0)
+        fld ft10, 0x1F0(a0)
+        fld ft11, 0x1F8(a0)
+        "
+    };
+}
+
+#[naked]
+pub extern "C-unwind" fn save_context() -> Context {
+    // No need to save caller-saved registers here.
+    #[cfg(target_feature = "d")]
+    unsafe {
+        asm!(
+            concat!(code!(save_gp), code!(save_fp), "ret"),
+            options(noreturn)
+        );
+    }
+    #[cfg(not(target_feature = "d"))]
+    unsafe {
+        asm!(
+            concat!(code!(save_gp), "ret"),
+            options(noreturn)
+        );
+    }
+}
+
+#[naked]
+pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
+    #[cfg(target_feature = "d")]
+    unsafe {
+        asm!(
+            concat!(code!(restore_fp), code!(restore_gp), "ld a0, 0x50(a0)\nret"),
+            options(noreturn)
+        );
+    }
+    #[cfg(not(target_feature = "d"))]
+    unsafe {
+        asm!(
+            concat!(code!(restore_gp), "ld a0, 0x50(a0)\nret"),
+            options(noreturn)
+        );
+    }
+}