Add arch support for LoongArch64

.github/workflows/ci.yml

@@ -15,6 +15,7 @@ jobs:
           - aarch64-unknown-linux-gnu
           - riscv64gc-unknown-linux-gnu
           - riscv32gc-unknown-linux-gnu
+          - loongarch64-unknown-linux-gnu
     runs-on: ubuntu-latest
 
     steps:

README.md

@@ -9,7 +9,7 @@ This library serves two purposes:
 1. Provide a pure Rust alternative to libgcc_eh or libunwind.
 2. Provide easier unwinding support for `#![no_std]` targets.
 
-Currently supports x86_64, x86, RV64, RV32 and AArch64.
+Currently supports x86_64, x86, RV64, RV32, AArch64, and LoongArch64.
 
 ## Unwinder
 

src/arch.rs

@@ -70,11 +70,30 @@ mod aarch64 {
 #[cfg(target_arch = "aarch64")]
 pub use aarch64::*;
 
+#[cfg(target_arch = "loongarch64")]
+mod loongarch64 {
+    use gimli::{LoongArch, Register};
+
+    pub struct Arch;
+
+    #[allow(unused)]
+    impl Arch {
+        pub const SP: Register = LoongArch::SP;
+        pub const RA: Register = LoongArch::RA;
+
+        pub const UNWIND_DATA_REG: (Register, Register) = (LoongArch::A0, LoongArch::A1);
+        pub const UNWIND_PRIVATE_DATA_SIZE: usize = 2;
+    }
+}
+#[cfg(target_arch = "loongarch64")]
+pub use loongarch64::*;
+
 #[cfg(not(any(
     target_arch = "x86_64",
     target_arch = "x86",
     target_arch = "riscv64",
     target_arch = "riscv32",
-    target_arch = "aarch64"
+    target_arch = "aarch64",
+    target_arch = "loongarch64"
 )))]
 compile_error!("Current architecture is not supported");

src/unwinder/arch/loongarch64.rs

@@ -0,0 +1,247 @@
+use core::{fmt, ops};
+use gimli::{LoongArch, Register};
+
+use super::maybe_cfi;
+
+// https://github.com/loongson/la-abi-specs/blob/release/ladwarf.adoc
+pub const MAX_REG_RULES: usize = 65;
+
+#[repr(C)]
+#[derive(Clone, Default)]
+pub struct Context {
+    pub gp: [usize; 32],
+    // sp is gp[3]
+    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(
+                LoongArch::register_name(Register(i as _)).unwrap(),
+                &format_args!("{:#x}", self.gp[i]),
+            );
+        }
+        fmt.field("sp", &self.gp[3]);
+        for i in 0..=31 {
+            fmt.field(
+                LoongArch::register_name(Register((i + 32) as _)).unwrap(),
+                &format_args!("{:#x}", 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! save_regs {
+    (gp$(, $fp:ident)?) => {
+        core::arch::naked_asm!(
+            maybe_cfi!(".cfi_startproc"),
+            "
+            move $r12, $r3
+            addi.d $r3, $r3, -0x210
+            ",
+            maybe_cfi!(".cfi_def_cfa_offset 0x210"),
+            "
+            st.d $r1, $r3, 0x200
+            ",
+            maybe_cfi!(".cfi_offset 1, -16"), // ra
+            helper!(save_gp),
+            save_regs!(maybe_save_fp($($fp)?)),
+            "
+            move $r12, $r4
+            move $r4, $r3 // argument a0 pointing the ctx base
+
+            addi.d $r13, $r3, 0x210
+            st.d $r13, $r3, 0x18 // save sp
+
+            jirl $r1, $r12, 0 // call f
+
+            ld.d $r1, $r3, 0x200
+            addi.d $r3, $r3, 0x210 // restore ra and sp
+            ",
+            maybe_cfi!(".cfi_def_cfa_offset 0"),
+            maybe_cfi!(".cfi_restore 1"), // ra
+            "
+            ret
+            ",
+            maybe_cfi!(".cfi_endproc"),
+        )
+    };
+    (maybe_save_fp(fp)) => {
+        helper!(save_fp)
+    };
+    (maybe_save_fp()) => {
+        ""
+    };
+}
+
+macro_rules! restore_regs {
+    ($ctx:expr, gp$(, $fp:ident)?) => {
+        core::arch::asm!(
+            restore_regs!(maybe_restore_fp($($fp)?)),
+            helper!(restore_gp),
+            "
+            ld.d $r4, $r4, 0x20
+            ret
+            ",
+            in("$r4") $ctx,
+            options(noreturn)
+        )
+    };
+    (maybe_restore_fp(fp)) => {
+        helper!(restore_fp)
+    };
+    (maybe_restore_fp()) => {
+        ""
+    };
+}
+
+macro_rules! helper {
+    // see https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html for ABI conventions
+    (save_gp) => {
+        "
+        st.d $r0, $r3, 0x0 // zero
+        st.d $r1, $r3, 0x8 // ra
+        st.d $r2, $r3, 0x10 // tp
+        // sp is saved later
+        st.d $r21, $r3, 0xa8 // reserved
+        st.d $r22, $r3, 0xb0 // fp
+        st.d $r23, $r3, 0xb8 // s0
+        st.d $r24, $r3, 0xc0 // s1
+        st.d $r25, $r3, 0xc8 // s2
+        st.d $r26, $r3, 0xd0 // s3
+        st.d $r27, $r3, 0xd8 // s4
+        st.d $r28, $r3, 0xe0 // s5
+        st.d $r29, $r3, 0xe8 // s6
+        st.d $r30, $r3, 0xf0 // s7
+        st.d $r31, $r3, 0xf8 // s8
+        "
+    };
+    (save_fp) => {
+        "
+        fst.d $f24, $r3, 0x1c0 // fs0
+        fst.d $f25, $r3, 0x1c8 // fs1
+        fst.d $f26, $r3, 0x1d0 // fs2
+        fst.d $f27, $r3, 0x1d8 // fs3
+        fst.d $f28, $r3, 0x1e0 // fs4
+        fst.d $f29, $r3, 0x1e8 // fs5
+        fst.d $f30, $r3, 0x1f0 // fs6
+        fst.d $f31, $r3, 0x1f8 // fs7
+        "
+    };
+    (restore_gp) => {
+        "
+        ld.d $r1, $r4, 0x8 // ra
+        ld.d $r2, $r4, 0x10 // tp
+        ld.d $r3, $r4, 0x18 // sp
+        // r4(a0) is restored later
+        ld.d $r5, $r4, 0x28 // a1
+        ld.d $r6, $r4, 0x30 // a2
+        ld.d $r7, $r4, 0x38 // a3
+        ld.d $r8, $r4, 0x40 // a4
+        ld.d $r9, $r4, 0x48 // a5
+        ld.d $r10, $r4, 0x50 // a6
+        ld.d $r11, $r4, 0x58 // a7
+        ld.d $r12, $r4, 0x60 // t0
+        ld.d $r13, $r4, 0x68 // t1
+        ld.d $r14, $r4, 0x70 // t2
+        ld.d $r15, $r4, 0x78 // t3
+        ld.d $r16, $r4, 0x80 // t4
+        ld.d $r17, $r4, 0x88 // t5
+        ld.d $r18, $r4, 0x90 // t6
+        ld.d $r19, $r4, 0x98 // t7
+        ld.d $r20, $r4, 0xa0 // t8
+        ld.d $r21, $r4, 0xa8 // reserved
+        ld.d $r22, $r4, 0xb0 // fp
+        ld.d $r23, $r4, 0xb8 // s0
+        ld.d $r24, $r4, 0xc0 // s1
+        ld.d $r25, $r4, 0xc8 // s2
+        ld.d $r26, $r4, 0xd0 // s3
+        ld.d $r27, $r4, 0xd8 // s4
+        ld.d $r28, $r4, 0xe0 // s5
+        ld.d $r29, $r4, 0xe8 // s6
+        ld.d $r30, $r4, 0xf0 // s7
+        ld.d $r31, $r4, 0xf8 // s8
+        "
+    };
+    (restore_fp) => {
+        "
+        fld.d $f0, $r4, 0x100 // fa0
+        fld.d $f1, $r4, 0x108 // fa1
+        fld.d $f2, $r4, 0x110 // fa2
+        fld.d $f3, $r4, 0x118 // fa3
+        fld.d $f4, $r4, 0x120 // fa4
+        fld.d $f5, $r4, 0x128 // fa5
+        fld.d $f6, $r4, 0x130 // fa6
+        fld.d $f7, $r4, 0x138 // fa7
+        fld.d $f8, $r4, 0x140 // ft0
+        fld.d $f9, $r4, 0x148 // ft1
+        fld.d $f10, $r4, 0x150 // ft2
+        fld.d $f11, $r4, 0x158 // ft3
+        fld.d $f12, $r4, 0x160 // ft4
+        fld.d $f13, $r4, 0x168 // ft5
+        fld.d $f14, $r4, 0x170 // ft6
+        fld.d $f15, $r4, 0x178 // ft7
+        fld.d $f16, $r4, 0x180 // ft8
+        fld.d $f17, $r4, 0x188 // ft9
+        fld.d $f18, $r4, 0x190 // ft10
+        fld.d $f19, $r4, 0x198 // ft11
+        fld.d $f20, $r4, 0x1a0 // ft12
+        fld.d $f21, $r4, 0x1a8 // ft13
+        fld.d $f22, $r4, 0x1b0 // ft14
+        fld.d $f23, $r4, 0x1b8 // ft15
+        fld.d $f24, $r4, 0x1c0 // fs0
+        fld.d $f25, $r4, 0x1c8 // fs1
+        fld.d $f26, $r4, 0x1d0 // fs2
+        fld.d $f27, $r4, 0x1d8 // fs3
+        fld.d $f28, $r4, 0x1e0 // fs4
+        fld.d $f29, $r4, 0x1e8 // fs5
+        fld.d $f30, $r4, 0x1f0 // fs6
+        fld.d $f31, $r4, 0x1f8 // fs7
+        "
+    };
+}
+
+#[unsafe(naked)]
+pub extern "C-unwind" fn save_context(f: extern "C" fn(&mut Context, *mut ()), ptr: *mut ()) {
+    #[allow(unused_unsafe)]
+    unsafe {
+        #[cfg(target_feature = "d")]
+        save_regs!(gp, fp);
+        #[cfg(not(target_feature = "d"))]
+        save_regs!(gp);
+    }
+}
+
+pub unsafe fn restore_context(ctx: &Context) -> ! {
+    unsafe {
+        #[cfg(target_feature = "d")]
+        restore_regs!(ctx, gp, fp);
+        #[cfg(not(target_feature = "d"))]
+        restore_regs!(ctx, gp);
+    }
+}

src/unwinder/arch/mod.rs

@@ -23,12 +23,18 @@ mod aarch64;
 #[cfg(target_arch = "aarch64")]
 pub use aarch64::*;
 
+#[cfg(target_arch = "loongarch64")]
+mod loongarch64;
+#[cfg(target_arch = "loongarch64")]
+pub use loongarch64::*;
+
 #[cfg(not(any(
     target_arch = "x86_64",
     target_arch = "x86",
     target_arch = "riscv64",
     target_arch = "riscv32",
-    target_arch = "aarch64"
+    target_arch = "aarch64",
+    target_arch = "loongarch64"
 )))]
 compile_error!("Current architecture is not supported");