Update to latest upstream

.github/workflows/ci.yml

@@ -0,0 +1,35 @@
+name: CI
+
+on: [push, pull_request]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        target:
+          - x86_64-unknown-linux-gnu
+          - i686-unknown-linux-gnu
+          - aarch64-unknown-linux-gnu
+          - riscv64gc-unknown-linux-gnu
+          - riscv32gc-unknown-linux-gnu
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install Rust
+      run: |
+        rustup update nightly
+        rustup default nightly
+    - name: Install cross-compilation tools
+      uses: taiki-e/setup-cross-toolchain-action@v1
+      with:
+        target: ${{ matrix.target }}
+
+    - name: Build library
+      run: cargo build --release $BUILD_STD
+
+    - name: Run tests
+      run: cargo test --release $BUILD_STD

.gitignore

@@ -1,3 +1,2 @@
 .vscode/
 target
-Cargo.lock

Cargo.lock

@@ -0,0 +1,87 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "catch_std_exception"
+version = "0.1.0"
+dependencies = [
+ "libc",
+ "unwinding",
+]
+
+[[package]]
+name = "compiler_builtins"
+version = "0.1.101"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01a6d58e9c3408138099a396a98fd0d0e6cfb25d723594d2ae48b5004513fd5b"
+
+[[package]]
+name = "gimli"
+version = "0.28.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6fb8d784f27acf97159b40fc4db5ecd8aa23b9ad5ef69cdd136d3bc80665f0c0"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.149"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a08173bc88b7955d1b3145aa561539096c421ac8debde8cbc3612ec635fee29b"
+
+[[package]]
+name = "rustc-std-workspace-alloc"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ff66d57013a5686e1917ed6a025d54dd591fcda71a41fe07edf4d16726aefa86"
+
+[[package]]
+name = "rustc-std-workspace-core"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1956f5517128a2b6f23ab2dadf1a976f4f5b27962e7724c2bf3d45e539ec098c"
+
+[[package]]
+name = "spin"
+version = "0.9.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+
+[[package]]
+name = "std_catch_exception"
+version = "0.1.0"
+dependencies = [
+ "libc",
+ "unwinding",
+]
+
+[[package]]
+name = "throw_and_catch"
+version = "0.1.0"
+dependencies = [
+ "libc",
+ "unwinding",
+]
+
+[[package]]
+name = "unwinding"
+version = "0.2.1"
+dependencies = [
+ "compiler_builtins",
+ "gimli",
+ "libc",
+ "rustc-std-workspace-core",
+ "spin",
+]
+
+[[package]]
+name = "unwinding_dyn"
+version = "0.1.0"
+dependencies = [
+ "libc",
+ "unwinding",
+]

Cargo.toml

@@ -1,16 +1,18 @@
 [package]
 name = "unwinding"
-version = "0.1.5"
+version = "0.2.1"
 authors = ["Gary Guo <gary@garyguo.net>"]
-edition = "2018"
+edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "Unwinding library in Rust and for Rust"
 repository = "https://github.com/nbdd0121/unwinding/"
 
 [dependencies]
-gimli = { version = "0.26.1", default-features = false, features = ["read-core"] }
+gimli = { version = "0.28", default-features = false, features = ["read-core"] }
 libc = { version = "0.2", optional = true }
-spin = { version = "0.9", optional = true, default-features = false, features = ["mutex", "spin_mutex"] }
+spin = { version = "0.9.8", optional = true, default-features = false, features = ["mutex", "spin_mutex"] }
+core = { version = '1.0.0', optional = true, package = 'rustc-std-workspace-core' }
+compiler_builtins = { version = "0.1.2", optional = true }
 
 [features]
 alloc = []
@@ -21,6 +23,7 @@ fde-phdr-aux = ["fde-phdr"]
 fde-registry = ["alloc"]
 fde-static = []
 fde-gnu-eh-frame-hdr = []
+fde-custom = []
 dwarf-expr = []
 hide-trace = []
 personality = []
@@ -32,6 +35,7 @@ panic-handler = ["print", "panic"]
 panic-handler-dummy = []
 system-alloc = []
 default = ["unwinder", "dwarf-expr", "hide-trace", "fde-phdr-dl", "fde-registry"]
+rustc-dep-of-std = ["core", "gimli/rustc-dep-of-std", "compiler_builtins"]
 
 [package.metadata.docs.rs]
 features = ["panic-handler"]

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 and AArch64.
+Currently supports x86_64, x86, RV64, RV32 and AArch64.
 
 ## Unwinder
 
@@ -23,6 +23,7 @@ The unwinder can be enabled with `unwinder` feature. Here are the feature gates
 | fde-registry         | Yes     | Provide `__register__frame` and others for dynamic registration. Requires either `libc` or `spin` for a mutex implementation. |
 | fde-gnu-eh-frame-hdr | No      | Use `__executable_start`, `__etext` and `__GNU_EH_FRAME_HDR` to retrieve frame unwind table. The former two symbols are usually provided by the linker, while the last one is provided if GNU LD is used and --eh-frame-hdr option is enabled. |
 | fde-static           | No      | Use `__executable_start`, `__etext` and `__eh_frame` to retrieve frame unwind table. The former two symbols are usually provided by the linker, while the last one would need to be provided by the user via linker script.  |
+| fde-custom           | No      | Allow the program to provide a custom means of retrieving frame unwind table at runtime via the `set_custom_eh_frame_finder` function. |
 | dwarf-expr           | Yes     | Enable the dwarf expression evaluator. Usually not necessary for Rust |
 | hide-trace           | Yes     | Hide unwinder frames in back trace |
 

rust-toolchain

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "nightly"

src/abi.rs

@@ -60,11 +60,11 @@ impl UnwindAction {
 
 pub type UnwindExceptionCleanupFn = unsafe extern "C" fn(UnwindReasonCode, *mut UnwindException);
 
-pub type UnwindStopFn = extern "C" fn(
+pub type UnwindStopFn = unsafe extern "C" fn(
     c_int,
     UnwindAction,
     u64,
-    &mut UnwindException,
+    *mut UnwindException,
     &mut UnwindContext<'_>,
     *mut c_void,
 ) -> UnwindReasonCode;
@@ -78,7 +78,7 @@ pub struct UnwindException {
 }
 
 pub type UnwindTraceFn =
-    extern "C" fn(ctx: &mut UnwindContext<'_>, arg: *mut c_void) -> UnwindReasonCode;
+    extern "C" fn(ctx: &UnwindContext<'_>, arg: *mut c_void) -> UnwindReasonCode;
 
 #[cfg(not(feature = "unwinder"))]
 #[repr(C)]
@@ -87,31 +87,49 @@ pub struct UnwindContext<'a> {
     phantom: core::marker::PhantomData<&'a ()>,
 }
 
-pub type PersonalityRoutine = extern "C" fn(
+pub type PersonalityRoutine = unsafe extern "C" fn(
     c_int,
     UnwindAction,
     u64,
-    &mut UnwindException,
+    *mut UnwindException,
     &mut UnwindContext<'_>,
 ) -> UnwindReasonCode;
 
 #[cfg(not(feature = "unwinder"))]
 macro_rules! binding {
-    ($(extern $abi: literal $([$t:tt])? fn $name: ident ($($arg: ident : $arg_ty: ty),*$(,)?) $(-> $ret: ty)?;)*) => {
+    () => {};
-        $(
+    (unsafe extern $abi: literal fn $name: ident ($($arg: ident : $arg_ty: ty),*$(,)?) $(-> $ret: ty)?; $($rest: tt)*) => {
-            #[allow(non_snake_case)]
+        extern $abi {
-            #[inline]
+            pub fn $name($($arg: $arg_ty),*) $(-> $ret)?;
-            pub $($t)? fn $name($($arg: $arg_ty),*) $(-> $ret)? {
+        }
-                extern $abi {
+        binding!($($rest)*);
-                    fn $name($($arg: $arg_ty),*) $(-> $ret)?;
+    };
-                }
+
-                unsafe { $name($($arg),*) }
+    (extern $abi: literal fn $name: ident ($($arg: ident : $arg_ty: ty),*$(,)?) $(-> $ret: ty)?; $($rest: tt)*) => {
+        #[allow(non_snake_case)]
+        #[inline]
+        pub fn $name($($arg: $arg_ty),*) $(-> $ret)? {
+            extern $abi {
+                fn $name($($arg: $arg_ty),*) $(-> $ret)?;
             }
-        )*
+            unsafe { $name($($arg),*) }
+        }
+        binding!($($rest)*);
+    };
+}
+
+#[cfg(feature = "unwinder")]
+macro_rules! binding {
+    () => {};
+    (unsafe extern $abi: literal fn $name: ident ($($arg: ident : $arg_ty: ty),*$(,)?) $(-> $ret: ty)?; $($rest: tt)*) => {
+        const _: unsafe extern $abi fn($($arg_ty),*) $(-> $ret)? = $name;
+    };
+
+    (extern $abi: literal fn $name: ident ($($arg: ident : $arg_ty: ty),*$(,)?) $(-> $ret: ty)?; $($rest: tt)*) => {
+        const _: extern $abi fn($($arg_ty),*) $(-> $ret)? = $name;
     };
 }
 
-#[cfg(not(feature = "unwinder"))]
 binding! {
     extern "C" fn _Unwind_GetGR(unwind_ctx: &UnwindContext<'_>, index: c_int) -> usize;
     extern "C" fn _Unwind_GetCFA(unwind_ctx: &UnwindContext<'_>) -> usize;
@@ -134,19 +152,19 @@ binding! {
     extern "C" fn _Unwind_GetTextRelBase(unwind_ctx: &UnwindContext<'_>) -> usize;
     extern "C" fn _Unwind_GetDataRelBase(unwind_ctx: &UnwindContext<'_>) -> usize;
     extern "C" fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void;
-    extern "C-unwind" fn _Unwind_RaiseException(
+    unsafe extern "C-unwind" fn _Unwind_RaiseException(
-        exception: &mut UnwindException,
+        exception: *mut UnwindException,
     ) -> UnwindReasonCode;
-    extern "C-unwind" fn _Unwind_ForcedUnwind(
+    unsafe extern "C-unwind" fn _Unwind_ForcedUnwind(
-        exception: &mut UnwindException,
+        exception: *mut UnwindException,
         stop: UnwindStopFn,
         stop_arg: *mut c_void,
     ) -> UnwindReasonCode;
-    extern "C-unwind" fn _Unwind_Resume(exception: &mut UnwindException) -> !;
+    unsafe extern "C-unwind" fn _Unwind_Resume(exception: *mut UnwindException) -> !;
-    extern "C-unwind" fn _Unwind_Resume_or_Rethrow(
+    unsafe extern "C-unwind" fn _Unwind_Resume_or_Rethrow(
-        exception: &mut UnwindException,
+        exception: *mut UnwindException,
     ) -> UnwindReasonCode;
-    extern "C" [unsafe] fn _Unwind_DeleteException(exception: *mut UnwindException);
+    unsafe extern "C" fn _Unwind_DeleteException(exception: *mut UnwindException);
     extern "C-unwind" fn _Unwind_Backtrace(
         trace: UnwindTraceFn,
         trace_argument: *mut c_void,

src/lib.rs

@@ -1,6 +1,18 @@
 #![doc = include_str!("../README.md")]
 #![feature(c_unwind)]
 #![feature(naked_functions)]
+#![feature(non_exhaustive_omitted_patterns_lint)]
+// lang_items is an internal feature. `internal_features` lint is added recently
+// so also allow unknown lints to prevent warning in older nightly versions.
+#![cfg_attr(
+    any(
+        feature = "personality",
+        feature = "personality-dummy",
+        feature = "panicking",
+        feature = "panic-handler-dummy"
+    ),
+    allow(internal_features)
+)]
 #![cfg_attr(
     any(feature = "personality", feature = "personality-dummy"),
     feature(lang_items)
@@ -20,6 +32,9 @@ extern crate alloc;
 #[cfg(feature = "unwinder")]
 mod unwinder;
 
+#[cfg(all(feature = "unwinder", feature = "fde-custom"))]
+pub use unwinder::custom_eh_frame_finder;
+
 pub mod abi;
 
 mod arch;
@@ -30,7 +45,7 @@ pub mod print;
 
 #[cfg(feature = "personality")]
 mod personality;
-#[cfg(feature = "personality-dummy")]
+#[cfg(all(not(feature = "personality"), feature = "personality-dummy"))]
 mod personality_dummy;
 
 #[cfg(feature = "panic")]
@@ -40,7 +55,7 @@ pub mod panicking;
 
 #[cfg(feature = "panic-handler")]
 mod panic_handler;
-#[cfg(feature = "panic-handler-dummy")]
+#[cfg(all(not(feature = "panic-handler"), feature = "panic-handler-dummy"))]
 mod panic_handler_dummy;
 
 #[cfg(feature = "system-alloc")]

src/panic.rs

@@ -7,6 +7,8 @@ use crate::abi::*;
 pub use crate::panic_handler::*;
 use crate::panicking::Exception;
 
+static CANARY: u8 = 0;
+
 #[repr(transparent)]
 struct RustPanic(Box<dyn Any + Send>, DropGuard);
 
@@ -18,13 +20,15 @@ impl Drop for DropGuard {
         {
             drop_panic();
         }
-        core::intrinsics::abort();
+        crate::util::abort();
     }
 }
 
 #[repr(C)]
 struct ExceptionWithPayload {
     exception: MaybeUninit<UnwindException>,
+    // See rust/library/panic_unwind/src/gcc.rs for the canary values
+    canary: *const u8,
     payload: RustPanic,
 }
 
@@ -34,12 +38,23 @@ unsafe impl Exception for RustPanic {
     fn wrap(this: Self) -> *mut UnwindException {
         Box::into_raw(Box::new(ExceptionWithPayload {
             exception: MaybeUninit::uninit(),
+            canary: &CANARY,
             payload: this,
         })) as *mut UnwindException
     }
 
     unsafe fn unwrap(ex: *mut UnwindException) -> Self {
-        let ex = unsafe { Box::from_raw(ex as *mut ExceptionWithPayload) };
+        let ex = ex as *mut ExceptionWithPayload;
+        let canary = unsafe { core::ptr::addr_of!((*ex).canary).read() };
+        if !core::ptr::eq(canary, &CANARY) {
+            // This is a Rust exception but not generated by us.
+            #[cfg(feature = "panic-handler")]
+            {
+                foreign_exception();
+            }
+            crate::util::abort();
+        }
+        let ex = unsafe { Box::from_raw(ex) };
         ex.payload
     }
 }
@@ -57,7 +72,7 @@ pub fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
                 {
                     foreign_exception();
                 }
-                core::intrinsics::abort();
+                crate::util::abort();
             }
             Some(e) => {
                 #[cfg(feature = "panic-handler")]

src/panic_handler.rs

@@ -59,10 +59,7 @@ fn stack_trace() {
     struct CallbackData {
         counter: usize,
     }
-    extern "C" fn callback(
+    extern "C" fn callback(unwind_ctx: &UnwindContext<'_>, arg: *mut c_void) -> UnwindReasonCode {
-        unwind_ctx: &mut UnwindContext<'_>,
-        arg: *mut c_void,
-    ) -> UnwindReasonCode {
         let data = unsafe { &mut *(arg as *mut CallbackData) };
         data.counter += 1;
         eprintln!(
@@ -80,7 +77,7 @@ fn do_panic(msg: Box<dyn Any + Send>) -> ! {
     if PANIC_COUNT.get() >= 1 {
         stack_trace();
         eprintln!("thread panicked while processing panic. aborting.");
-        core::intrinsics::abort();
+        crate::util::abort();
     }
     PANIC_COUNT.set(1);
     if check_env() {
@@ -88,7 +85,7 @@ fn do_panic(msg: Box<dyn Any + Send>) -> ! {
     }
     let code = crate::panic::begin_panic(Box::new(msg));
     eprintln!("failed to initiate panic, error {}", code.0);
-    core::intrinsics::abort();
+    crate::util::abort();
 }
 
 #[panic_handler]

src/panic_handler_dummy.rs

@@ -2,5 +2,5 @@ use core::panic::PanicInfo;
 
 #[panic_handler]
 fn panic(_info: &PanicInfo<'_>) -> ! {
-    core::intrinsics::abort();
+    crate::util::abort();
 }

src/panicking.rs

@@ -21,7 +21,7 @@ pub fn begin_panic<E: Exception>(exception: E) -> UnwindReasonCode {
     unsafe {
         (*ex).exception_class = u64::from_be_bytes(E::CLASS);
         (*ex).exception_cleanup = Some(exception_cleanup::<E>);
-        _Unwind_RaiseException(&mut *ex)
+        _Unwind_RaiseException(ex)
     }
 }
 
@@ -39,7 +39,7 @@ pub fn catch_unwind<E: Exception, R, F: FnOnce() -> R>(f: F) -> Result<R, Option
 
     let data_ptr = &mut data as *mut _ as *mut u8;
     unsafe {
-        return if core::intrinsics::r#try(do_call::<F, R>, data_ptr, do_catch::<E>) == 0 {
+        return if core::intrinsics::catch_unwind(do_call::<F, R>, data_ptr, do_catch::<E>) == 0 {
             Ok(ManuallyDrop::into_inner(data.r))
         } else {
             Err(ManuallyDrop::into_inner(data.p))

src/personality.rs

@@ -136,11 +136,11 @@ fn find_eh_action(
 }
 
 #[lang = "eh_personality"]
-fn rust_eh_personality(
+unsafe fn rust_eh_personality(
     version: c_int,
     actions: UnwindAction,
     _exception_class: u64,
-    exception: &mut UnwindException,
+    exception: *mut UnwindException,
     unwind_ctx: &mut UnwindContext<'_>,
 ) -> UnwindReasonCode {
     if version != 1 {
@@ -170,7 +170,7 @@ fn rust_eh_personality(
                 _Unwind_SetGR(
                     unwind_ctx,
                     Arch::UNWIND_DATA_REG.0 .0 as _,
-                    exception as *mut _ as usize,
+                    exception as usize,
                 );
                 _Unwind_SetGR(unwind_ctx, Arch::UNWIND_DATA_REG.1 .0 as _, 0);
                 _Unwind_SetIP(unwind_ctx, lpad);

src/personality_dummy.rs

@@ -2,11 +2,11 @@ use crate::abi::*;
 use crate::util::*;
 
 #[lang = "eh_personality"]
-extern "C" fn personality(
+unsafe extern "C" fn personality(
     version: c_int,
     _actions: UnwindAction,
     _exception_class: u64,
-    _exception: &mut UnwindException,
+    _exception: *mut UnwindException,
     _ctx: &mut UnwindContext<'_>,
 ) -> UnwindReasonCode {
     if version != 1 {

src/print.rs

@@ -49,3 +49,22 @@ macro_rules! eprint {
         let _ = core::write!($crate::print::StderrPrinter, $($arg)*);
     })
 }
+
+#[macro_export]
+macro_rules! dbg {
+    () => {
+        $crate::eprintln!("[{}:{}]", ::core::file!(), ::core::line!())
+    };
+    ($val:expr $(,)?) => {
+        match $val {
+            tmp => {
+                $crate::eprintln!("[{}:{}] {} = {:#?}",
+                    ::core::file!(), ::core::line!(), ::core::stringify!($val), &tmp);
+                tmp
+            }
+        }
+    };
+    ($($val:expr),+ $(,)?) => {
+        ($($crate::dbg!($val)),+,)
+    };
+}

src/unwinder/arch/aarch64.rs

@@ -59,25 +59,34 @@ impl ops::IndexMut<gimli::Register> for Context {
 }
 
 #[naked]
-pub extern "C-unwind" fn save_context() -> Context {
+pub extern "C-unwind" fn save_context(f: extern "C" fn(&mut Context, *mut ()), ptr: *mut ()) {
     // No need to save caller-saved registers here.
     unsafe {
         asm!(
             "
-            stp d8, d9, [x8, 0x140]
+            stp x29, x30, [sp, -16]!
-            stp d10, d11, [x8, 0x150]
+            sub sp, sp, 512
-            stp d12, d13, [x8, 0x160]
+            mov x8, x0
-            stp d14, d15, [x8, 0x170]
-
-            str x19, [x8, 0x98]
-            stp x20, x21, [x8, 0xA0]
-            stp x22, x23, [x8, 0xB0]
-            stp x24, x25, [x8, 0xC0]
-            stp x26, x27, [x8, 0xD0]
-            stp x28, x29, [x8, 0xE0]
             mov x0, sp
-            stp x30, x0, [x8, 0xF0]
 
+            stp d8, d9, [sp, 0x140]
+            stp d10, d11, [sp, 0x150]
+            stp d12, d13, [sp, 0x160]
+            stp d14, d15, [sp, 0x170]
+
+            str x19, [sp, 0x98]
+            stp x20, x21, [sp, 0xA0]
+            stp x22, x23, [sp, 0xB0]
+            stp x24, x25, [sp, 0xC0]
+            stp x26, x27, [sp, 0xD0]
+            stp x28, x29, [sp, 0xE0]
+            add x2, sp, 528
+            stp x30, x2, [sp, 0xF0]
+
+            blr x8
+
+            add sp, sp, 512
+            ldp x29, x30, [sp], 16
             ret
             ",
             options(noreturn)
@@ -85,8 +94,7 @@ pub extern "C-unwind" fn save_context() -> Context {
     }
 }
 
-#[naked]
+pub unsafe fn restore_context(ctx: &Context) -> ! {
-pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
     unsafe {
         asm!(
             "
@@ -127,6 +135,7 @@ pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
             ldp x0, x1, [x0, 0x00]
             ret
             ",
+            in("x0") ctx,
             options(noreturn)
         );
     }

src/unwinder/arch/mod.rs

@@ -13,6 +13,11 @@ mod riscv64;
 #[cfg(target_arch = "riscv64")]
 pub use riscv64::*;
 
+#[cfg(target_arch = "riscv32")]
+mod riscv32;
+#[cfg(target_arch = "riscv32")]
+pub use riscv32::*;
+
 #[cfg(target_arch = "aarch64")]
 mod aarch64;
 #[cfg(target_arch = "aarch64")]
@@ -22,6 +27,7 @@ pub use aarch64::*;
     target_arch = "x86_64",
     target_arch = "x86",
     target_arch = "riscv64",
+    target_arch = "riscv32",
     target_arch = "aarch64"
 )))]
 compile_error!("Current architecture is not supported");

src/unwinder/arch/riscv32.rs

@@ -0,0 +1,243 @@
+use core::arch::asm;
+use core::fmt;
+use core::ops;
+use gimli::{Register, RiscV};
+
+// Match DWARF_FRAME_REGISTERS in libgcc
+pub const MAX_REG_RULES: usize = 65;
+
+#[cfg(all(target_feature = "f", not(target_feature = "d")))]
+compile_error!("RISC-V with only F extension is not supported");
+
+#[repr(C)]
+#[derive(Clone, Default)]
+pub struct Context {
+    pub gp: [usize; 32],
+    #[cfg(target_feature = "d")]
+    pub fp: [u64; 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]);
+        }
+        #[cfg(target_feature = "d")]
+        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],
+            // We cannot support indexing fp here. It is 64-bit if D extension is implemented,
+            // and 32-bit if only F extension is implemented.
+            _ => 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],
+            // We cannot support indexing fp here. It is 64-bit if D extension is implemented,
+            // and 32-bit if only F extension is implemented.
+            _ => unimplemented!(),
+        }
+    }
+}
+
+macro_rules! code {
+    (save_gp) => {
+        "
+        sw x0, 0x00(sp)
+        sw ra, 0x04(sp)
+        sw t0, 0x08(sp)
+        sw gp, 0x0C(sp)
+        sw tp, 0x10(sp)
+        sw s0, 0x20(sp)
+        sw s1, 0x24(sp)
+        sw s2, 0x48(sp)
+        sw s3, 0x4C(sp)
+        sw s4, 0x50(sp)
+        sw s5, 0x54(sp)
+        sw s6, 0x58(sp)
+        sw s7, 0x5C(sp)
+        sw s8, 0x60(sp)
+        sw s9, 0x64(sp)
+        sw s10, 0x68(sp)
+        sw s11, 0x6C(sp)
+        "
+    };
+    (save_fp) => {
+        "
+        fsd fs0, 0xC0(sp)
+        fsd fs1, 0xC8(sp)
+        fsd fs2, 0x110(sp)
+        fsd fs3, 0x118(sp)
+        fsd fs4, 0x120(sp)
+        fsd fs5, 0x128(sp)
+        fsd fs6, 0x130(sp)
+        fsd fs7, 0x138(sp)
+        fsd fs8, 0x140(sp)
+        fsd fs9, 0x148(sp)
+        fsd fs10, 0x150(sp)
+        fsd fs11, 0x158(sp)
+        "
+    };
+    (restore_gp) => {
+        "
+        lw ra, 0x04(a0)
+        lw sp, 0x08(a0)
+        lw gp, 0x0C(a0)
+        lw tp, 0x10(a0)
+        lw t0, 0x14(a0)
+        lw t1, 0x18(a0)
+        lw t2, 0x1C(a0)
+        lw s0, 0x20(a0)
+        lw s1, 0x24(a0)
+        lw a1, 0x2C(a0)
+        lw a2, 0x30(a0)
+        lw a3, 0x34(a0)
+        lw a4, 0x38(a0)
+        lw a5, 0x3C(a0)
+        lw a6, 0x40(a0)
+        lw a7, 0x44(a0)
+        lw s2, 0x48(a0)
+        lw s3, 0x4C(a0)
+        lw s4, 0x50(a0)
+        lw s5, 0x54(a0)
+        lw s6, 0x58(a0)
+        lw s7, 0x5C(a0)
+        lw s8, 0x60(a0)
+        lw s9, 0x64(a0)
+        lw s10, 0x68(a0)
+        lw s11, 0x6C(a0)
+        lw t3, 0x70(a0)
+        lw t4, 0x74(a0)
+        lw t5, 0x78(a0)
+        lw t6, 0x7C(a0)
+        "
+    };
+    (restore_fp) => {
+        "
+        fld ft0, 0x80(a0)
+        fld ft1, 0x88(a0)
+        fld ft2, 0x90(a0)
+        fld ft3, 0x98(a0)
+        fld ft4, 0xA0(a0)
+        fld ft5, 0xA8(a0)
+        fld ft6, 0xB0(a0)
+        fld ft7, 0xB8(a0)
+        fld fs0, 0xC0(a0)
+        fld fs1, 0xC8(a0)
+        fld fa0, 0xD0(a0)
+        fld fa1, 0xD8(a0)
+        fld fa2, 0xE0(a0)
+        fld fa3, 0xE8(a0)
+        fld fa4, 0xF0(a0)
+        fld fa5, 0xF8(a0)
+        fld fa6, 0x100(a0)
+        fld fa7, 0x108(a0)
+        fld fs2, 0x110(a0)
+        fld fs3, 0x118(a0)
+        fld fs4, 0x120(a0)
+        fld fs5, 0x128(a0)
+        fld fs6, 0x130(a0)
+        fld fs7, 0x138(a0)
+        fld fs8, 0x140(a0)
+        fld fs9, 0x148(a0)
+        fld fs10, 0x150(a0)
+        fld fs11, 0x158(a0)
+        fld ft8, 0x160(a0)
+        fld ft9, 0x168(a0)
+        fld ft10, 0x170(a0)
+        fld ft11, 0x178(a0)
+        "
+    };
+}
+
+#[naked]
+pub extern "C-unwind" fn save_context(f: extern "C" fn(&mut Context, *mut ()), ptr: *mut ()) {
+    // No need to save caller-saved registers here.
+    #[cfg(target_feature = "d")]
+    unsafe {
+        asm!(
+            "
+            mv t0, sp
+            add sp, sp, -0x190
+            sw ra, 0x180(sp)
+            ",
+            code!(save_gp),
+            code!(save_fp),
+            "
+            mv t0, a0
+            mv a0, sp
+            jalr t0
+            lw ra, 0x180(sp)
+            add sp, sp, 0x190
+            ret
+            ",
+            options(noreturn)
+        );
+    }
+    #[cfg(not(target_feature = "d"))]
+    unsafe {
+        asm!(
+            "
+            mv t0, sp
+            add sp, sp, -0x90
+            sw ra, 0x80(sp)
+            ",
+            code!(save_gp),
+            "
+            mv t0, a0
+            mv a0, sp
+            jalr t0
+            lw ra, 0x80(sp)
+            add sp, sp, 0x90
+            ret
+            ",
+            options(noreturn)
+        );
+    }
+}
+
+pub unsafe fn restore_context(ctx: &Context) -> ! {
+    #[cfg(target_feature = "d")]
+    unsafe {
+        asm!(
+            code!(restore_fp),
+            code!(restore_gp),
+            "
+            lw a0, 0x28(a0)
+            ret
+            ",
+            in("a0") ctx,
+            options(noreturn)
+        );
+    }
+    #[cfg(not(target_feature = "d"))]
+    unsafe {
+        asm!(
+            code!(restore_gp),
+            "
+            lw a0, 0x28(a0)
+            ret
+            ",
+            in("a0") ctx,
+            options(noreturn)
+        );
+    }
+}

src/unwinder/arch/riscv64.rs

@@ -6,6 +6,9 @@ use gimli::{Register, RiscV};
 // Match DWARF_FRAME_REGISTERS in libgcc
 pub const MAX_REG_RULES: usize = 65;
 
+#[cfg(all(target_feature = "f", not(target_feature = "d")))]
+compile_error!("RISC-V with only F extension is not supported");
+
 #[repr(C)]
 #[derive(Clone, Default)]
 pub struct Context {
@@ -58,39 +61,39 @@ impl ops::IndexMut<gimli::Register> for Context {
 macro_rules! code {
     (save_gp) => {
         "
-        sd x0, 0x00(a0)
+        sd x0, 0x00(sp)
-        sd ra, 0x08(a0)
+        sd ra, 0x08(sp)
-        sd sp, 0x10(a0)
+        sd t0, 0x10(sp)
-        sd gp, 0x18(a0)
+        sd gp, 0x18(sp)
-        sd tp, 0x20(a0)
+        sd tp, 0x20(sp)
-        sd s0, 0x40(a0)
+        sd s0, 0x40(sp)
-        sd s1, 0x48(a0)
+        sd s1, 0x48(sp)
-        sd s2, 0x90(a0)
+        sd s2, 0x90(sp)
-        sd s3, 0x98(a0)
+        sd s3, 0x98(sp)
-        sd s4, 0xA0(a0)
+        sd s4, 0xA0(sp)
-        sd s5, 0xA8(a0)
+        sd s5, 0xA8(sp)
-        sd s6, 0xB0(a0)
+        sd s6, 0xB0(sp)
-        sd s7, 0xB8(a0)
+        sd s7, 0xB8(sp)
-        sd s8, 0xC0(a0)
+        sd s8, 0xC0(sp)
-        sd s9, 0xC8(a0)
+        sd s9, 0xC8(sp)
-        sd s10, 0xD0(a0)
+        sd s10, 0xD0(sp)
-        sd s11, 0xD8(a0)
+        sd s11, 0xD8(sp)
         "
     };
     (save_fp) => {
         "
-        fsd fs0, 0x140(a0)
+        fsd fs0, 0x140(sp)
-        fsd fs1, 0x148(a0)
+        fsd fs1, 0x148(sp)
-        fsd fs2, 0x190(a0)
+        fsd fs2, 0x190(sp)
-        fsd fs3, 0x198(a0)
+        fsd fs3, 0x198(sp)
-        fsd fs4, 0x1A0(a0)
+        fsd fs4, 0x1A0(sp)
-        fsd fs5, 0x1A8(a0)
+        fsd fs5, 0x1A8(sp)
-        fsd fs6, 0x1B0(a0)
+        fsd fs6, 0x1B0(sp)
-        fsd fs7, 0x1B8(a0)
+        fsd fs7, 0x1B8(sp)
-        fsd fs8, 0x1C0(a0)
+        fsd fs8, 0x1C0(sp)
-        fsd fs9, 0x1C8(a0)
+        fsd fs9, 0x1C8(sp)
-        fsd fs10, 0x1D0(a0)
+        fsd fs10, 0x1D0(sp)
-        fsd fs11, 0x1D8(a0)
+        fsd fs11, 0x1D8(sp)
         "
     };
     (restore_gp) => {
@@ -166,34 +169,74 @@ macro_rules! code {
 }
 
 #[naked]
-pub extern "C-unwind" fn save_context() -> Context {
+pub extern "C-unwind" fn save_context(f: extern "C" fn(&mut Context, *mut ()), ptr: *mut ()) {
     // No need to save caller-saved registers here.
     #[cfg(target_feature = "d")]
     unsafe {
         asm!(
-            concat!(code!(save_gp), code!(save_fp), "ret"),
+            "
+            mv t0, sp
+            add sp, sp, -0x210
+            sd ra, 0x200(sp)
+            ",
+            code!(save_gp),
+            code!(save_fp),
+            "
+            mv t0, a0
+            mv a0, sp
+            jalr t0
+            ld ra, 0x200(sp)
+            add sp, sp, 0x210
+            ret
+            ",
             options(noreturn)
         );
     }
     #[cfg(not(target_feature = "d"))]
     unsafe {
-        asm!(concat!(code!(save_gp), "ret"), options(noreturn));
+        asm!(
+            "
+            mv t0, sp
+            add sp, sp, -0x110
+            sd ra, 0x100(sp)
+            ",
+            code!(save_gp),
+            "
+            mv t0, a0
+            mv a0, sp
+            jalr t0
+            ld ra, 0x100(sp)
+            add sp, sp, 0x110
+            ret
+            ",
+            options(noreturn)
+        );
     }
 }
 
-#[naked]
+pub unsafe fn restore_context(ctx: &Context) -> ! {
-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"),
+            code!(restore_fp),
+            code!(restore_gp),
+            "
+            ld a0, 0x50(a0)
+            ret
+            ",
+            in("a0") ctx,
             options(noreturn)
         );
     }
     #[cfg(not(target_feature = "d"))]
     unsafe {
         asm!(
-            concat!(code!(restore_gp), "ld a0, 0x50(a0)\nret"),
+            code!(restore_gp),
+            "
+            ld a0, 0x50(a0)
+            ret
+            ",
+            in("a0") ctx,
             options(noreturn)
         );
     }

src/unwinder/arch/x86.rs

@@ -56,41 +56,50 @@ impl ops::IndexMut<gimli::Register> for Context {
 }
 
 #[naked]
-pub extern "C-unwind" fn save_context() -> Context {
+pub extern "C-unwind" fn save_context(f: extern "C" fn(&mut Context, *mut ()), ptr: *mut ()) {
     // No need to save caller-saved registers here.
     unsafe {
         asm!(
             "
-            mov eax, [esp + 4]
+            sub esp, 52
-            mov [eax + 4], ecx
+
-            mov [eax + 8], edx
+            mov [esp + 4], ecx
-            mov [eax + 12], ebx
+            mov [esp + 8], edx
-            mov [eax + 20], ebp
+            mov [esp + 12], ebx
-            mov [eax + 24], esi
-            mov [eax + 28], edi
 
             /* Adjust the stack to account for the return address */
-            lea edx, [esp + 4]
+            lea eax, [esp + 56]
-            mov [eax + 16], edx
+            mov [esp + 16], eax
 
-            mov edx, [esp]
+            mov [esp + 20], ebp
-            mov [eax + 32], edx
+            mov [esp + 24], esi
-            stmxcsr [eax + 36]
+            mov [esp + 28], edi
-            fnstcw [eax + 40]
+
-            ret 4
+            /* Return address */
+            mov eax, [esp + 52]
+            mov [esp + 32], eax
+
+            stmxcsr [esp + 36]
+            fnstcw [esp + 40]
+
+            mov eax, [esp + 60]
+            mov ecx, esp
+            push eax
+            push ecx
+            call [esp + 64]
+
+            add esp, 60
+            ret
             ",
             options(noreturn)
         );
     }
 }
 
-#[naked]
+pub unsafe fn restore_context(ctx: &Context) -> ! {
-pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
     unsafe {
         asm!(
             "
-            mov edx, [esp + 4]
-
             /* Restore stack */
             mov esp, [edx + 16]
 
@@ -118,6 +127,7 @@ pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
 
             ret
             ",
+            in("edx") ctx,
             options(noreturn)
         );
     }

src/unwinder/arch/x86_64.rs

@@ -58,27 +58,35 @@ impl ops::IndexMut<gimli::Register> for Context {
 }
 
 #[naked]
-pub extern "C-unwind" fn save_context() -> Context {
+pub extern "C-unwind" fn save_context(f: extern "C" fn(&mut Context, *mut ()), ptr: *mut ()) {
     // No need to save caller-saved registers here.
     unsafe {
         asm!(
             "
-            mov rax, rdi
+            sub rsp, 0x98
-            mov [rax + 0x18], rbx
+            mov [rsp + 0x18], rbx
-            mov [rax + 0x30], rbp
+            mov [rsp + 0x30], rbp
 
             /* Adjust the stack to account for the return address */
-            lea rdi, [rsp + 8]
+            lea rax, [rsp + 0xA0]
-            mov [rax + 0x38], rdi
+            mov [rsp + 0x38], rax
 
-            mov [rax + 0x60], r12
+            mov [rsp + 0x60], r12
-            mov [rax + 0x68], r13
+            mov [rsp + 0x68], r13
-            mov [rax + 0x70], r14
+            mov [rsp + 0x70], r14
-            mov [rax + 0x78], r15
+            mov [rsp + 0x78], r15
-            mov rdx, [rsp]
+
-            mov [rax + 0x80], rdx
+            /* Return address */
-            /* stmxcsr [rax + 0x88] */
+            mov rax, [rsp + 0x98]
-            fnstcw [rax + 0x90]
+            mov [rsp + 0x80], rax
+
+            /* stmxcsr [rsp + 0x88] */
+            fnstcw [rsp + 0x90]
+
+            mov rax, rdi
+            mov rdi, rsp
+            call rax
+            add rsp, 0x98
             ret
             ",
             options(noreturn)
@@ -86,8 +94,7 @@ pub extern "C-unwind" fn save_context() -> Context {
     }
 }
 
-#[naked]
+pub unsafe fn restore_context(ctx: &Context) -> ! {
-pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
     unsafe {
         asm!(
             "
@@ -121,11 +128,12 @@ pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
             mov r14, [rdi + 0x70]
             mov r15, [rdi + 0x78]
 
-            /* RDI resotred last */
+            /* RDI restored last */
             mov rdi, [rdi + 0x28]
 
             ret
             ",
+            in("rdi") ctx,
             options(noreturn)
         );
     }

src/unwinder/find_fde/custom.rs

@@ -0,0 +1,171 @@
+use super::{FDEFinder, FDESearchResult};
+use crate::util::{deref_pointer, get_unlimited_slice};
+
+use core::sync::atomic::{AtomicU32, Ordering};
+use gimli::{BaseAddresses, EhFrame, EhFrameHdr, NativeEndian, UnwindSection};
+
+pub(crate) struct CustomFinder(());
+
+pub(crate) fn get_finder() -> &'static CustomFinder {
+    &CustomFinder(())
+}
+
+impl FDEFinder for CustomFinder {
+    fn find_fde(&self, pc: usize) -> Option<FDESearchResult> {
+        get_custom_eh_frame_finder().and_then(|eh_frame_finder| find_fde(eh_frame_finder, pc))
+    }
+}
+
+/// A trait for types whose values can be used as the global EH frame finder set by [`set_custom_eh_frame_finder`].
+pub unsafe trait EhFrameFinder {
+    fn find(&self, pc: usize) -> Option<FrameInfo>;
+}
+
+pub struct FrameInfo {
+    pub text_base: Option<usize>,
+    pub kind: FrameInfoKind,
+}
+
+pub enum FrameInfoKind {
+    EhFrameHdr(usize),
+    EhFrame(usize),
+}
+
+static mut CUSTOM_EH_FRAME_FINDER: Option<&(dyn EhFrameFinder + Sync)> = None;
+
+static CUSTOM_EH_FRAME_FINDER_STATE: AtomicU32 = AtomicU32::new(UNINITIALIZED);
+
+const UNINITIALIZED: u32 = 0;
+const INITIALIZING: u32 = 1;
+const INITIALIZED: u32 = 2;
+
+/// The type returned by [`set_custom_eh_frame_finder`] if [`set_custom_eh_frame_finder`] has
+/// already been called.
+#[derive(Debug)]
+pub struct SetCustomEhFrameFinderError(());
+
+/// Sets the global EH frame finder.
+///
+/// This function should only be called once during the lifetime of the program.
+///
+/// # Errors
+///
+/// An error is returned if this function has already been called during the lifetime of the
+/// program.
+pub fn set_custom_eh_frame_finder(
+    fde_finder: &'static (dyn EhFrameFinder + Sync),
+) -> Result<(), SetCustomEhFrameFinderError> {
+    match CUSTOM_EH_FRAME_FINDER_STATE.compare_exchange(
+        UNINITIALIZED,
+        INITIALIZING,
+        Ordering::SeqCst,
+        Ordering::SeqCst,
+    ) {
+        Ok(UNINITIALIZED) => {
+            unsafe {
+                CUSTOM_EH_FRAME_FINDER = Some(fde_finder);
+            }
+            CUSTOM_EH_FRAME_FINDER_STATE.store(INITIALIZED, Ordering::SeqCst);
+            Ok(())
+        }
+        Err(INITIALIZING) => {
+            while CUSTOM_EH_FRAME_FINDER_STATE.load(Ordering::SeqCst) == INITIALIZING {
+                core::hint::spin_loop();
+            }
+            Err(SetCustomEhFrameFinderError(()))
+        }
+        Err(INITIALIZED) => Err(SetCustomEhFrameFinderError(())),
+        _ => {
+            unreachable!()
+        }
+    }
+}
+
+fn get_custom_eh_frame_finder() -> Option<&'static dyn EhFrameFinder> {
+    if CUSTOM_EH_FRAME_FINDER_STATE.load(Ordering::SeqCst) == INITIALIZED {
+        Some(unsafe { CUSTOM_EH_FRAME_FINDER.unwrap() })
+    } else {
+        None
+    }
+}
+
+fn find_fde<T: EhFrameFinder + ?Sized>(eh_frame_finder: &T, pc: usize) -> Option<FDESearchResult> {
+    let info = eh_frame_finder.find(pc)?;
+    let text_base = info.text_base;
+    match info.kind {
+        FrameInfoKind::EhFrameHdr(eh_frame_hdr) => {
+            find_fde_with_eh_frame_hdr(pc, text_base, eh_frame_hdr)
+        }
+        FrameInfoKind::EhFrame(eh_frame) => find_fde_with_eh_frame(pc, text_base, eh_frame),
+    }
+}
+
+fn find_fde_with_eh_frame_hdr(
+    pc: usize,
+    text_base: Option<usize>,
+    eh_frame_hdr: usize,
+) -> Option<FDESearchResult> {
+    unsafe {
+        let mut bases = BaseAddresses::default().set_eh_frame_hdr(eh_frame_hdr as _);
+        if let Some(text_base) = text_base {
+            bases = bases.set_text(text_base as _);
+        }
+        let eh_frame_hdr = EhFrameHdr::new(
+            get_unlimited_slice(eh_frame_hdr as usize as _),
+            NativeEndian,
+        )
+        .parse(&bases, core::mem::size_of::<usize>() as _)
+        .ok()?;
+        let eh_frame = deref_pointer(eh_frame_hdr.eh_frame_ptr());
+        let bases = bases.set_eh_frame(eh_frame as _);
+        let eh_frame = EhFrame::new(get_unlimited_slice(eh_frame as _), NativeEndian);
+
+        // Use binary search table for address if available.
+        if let Some(table) = eh_frame_hdr.table() {
+            if let Ok(fde) =
+                table.fde_for_address(&eh_frame, &bases, pc as _, EhFrame::cie_from_offset)
+            {
+                return Some(FDESearchResult {
+                    fde,
+                    bases,
+                    eh_frame,
+                });
+            }
+        }
+
+        // Otherwise do the linear search.
+        if let Ok(fde) = eh_frame.fde_for_address(&bases, pc as _, EhFrame::cie_from_offset) {
+            return Some(FDESearchResult {
+                fde,
+                bases,
+                eh_frame,
+            });
+        }
+
+        None
+    }
+}
+
+fn find_fde_with_eh_frame(
+    pc: usize,
+    text_base: Option<usize>,
+    eh_frame: usize,
+) -> Option<FDESearchResult> {
+    unsafe {
+        let mut bases = BaseAddresses::default().set_eh_frame(eh_frame as _);
+        if let Some(text_base) = text_base {
+            bases = bases.set_text(text_base as _);
+        }
+        let eh_frame = EhFrame::new(get_unlimited_slice(eh_frame as _), NativeEndian);
+
+        if let Ok(fde) = eh_frame.fde_for_address(&bases, pc as _, EhFrame::cie_from_offset) {
+            return Some(FDESearchResult {
+                fde,
+                bases,
+                eh_frame,
+            });
+        }
+
+        None
+    }
+}

src/unwinder/find_fde/mod.rs

@@ -1,3 +1,5 @@
+#[cfg(feature = "fde-custom")]
+mod custom;
 #[cfg(feature = "fde-static")]
 mod fixed;
 #[cfg(feature = "fde-gnu-eh-frame-hdr")]
@@ -10,6 +12,14 @@ mod registry;
 use crate::util::*;
 use gimli::{BaseAddresses, EhFrame, FrameDescriptionEntry};
 
+#[cfg(feature = "fde-custom")]
+pub mod custom_eh_frame_finder {
+    pub use super::custom::{
+        set_custom_eh_frame_finder, EhFrameFinder, FrameInfo, FrameInfoKind,
+        SetCustomEhFrameFinderError,
+    };
+}
+
 #[derive(Debug)]
 pub struct FDESearchResult {
     pub fde: FrameDescriptionEntry<StaticSlice>,
@@ -25,6 +35,10 @@ pub struct GlobalFinder(());
 
 impl FDEFinder for GlobalFinder {
     fn find_fde(&self, pc: usize) -> Option<FDESearchResult> {
+        #[cfg(feature = "fde-custom")]
+        if let Some(v) = custom::get_finder().find_fde(pc) {
+            return Some(v);
+        }
         #[cfg(feature = "fde-registry")]
         if let Some(v) = registry::get_finder().find_fde(pc) {
             return Some(v);

src/unwinder/find_fde/registry.rs

@@ -32,7 +32,7 @@ unsafe fn lock_global_state() -> impl ops::DerefMut<Target = GlobalState> {
     #[cfg(feature = "libc")]
     {
         static mut MUTEX: libc::pthread_mutex_t = libc::PTHREAD_MUTEX_INITIALIZER;
-        unsafe { libc::pthread_mutex_lock(&mut MUTEX) };
+        unsafe { libc::pthread_mutex_lock(core::ptr::addr_of_mut!(MUTEX)) };
 
         static mut STATE: GlobalState = GlobalState {
             object: ptr::null_mut(),
@@ -41,20 +41,22 @@ unsafe fn lock_global_state() -> impl ops::DerefMut<Target = GlobalState> {
         struct LockGuard;
         impl Drop for LockGuard {
             fn drop(&mut self) {
-                unsafe { libc::pthread_mutex_unlock(&mut MUTEX) };
+                unsafe { libc::pthread_mutex_unlock(core::ptr::addr_of_mut!(MUTEX)) };
             }
         }
 
         impl ops::Deref for LockGuard {
             type Target = GlobalState;
+
+            #[allow(static_mut_ref)]
             fn deref(&self) -> &GlobalState {
-                unsafe { &STATE }
+                unsafe { &*core::ptr::addr_of!(STATE) }
             }
         }
 
         impl ops::DerefMut for LockGuard {
             fn deref_mut(&mut self) -> &mut GlobalState {
-                unsafe { &mut STATE }
+                unsafe { &mut *core::ptr::addr_of_mut!(STATE) }
             }
         }
 

src/unwinder/frame.rs

@@ -125,6 +125,11 @@ impl Frame {
         Err(gimli::Error::UnsupportedEvaluation)
     }
 
+    pub fn adjust_stack_for_args(&self, ctx: &mut Context) {
+        let size = self.row.saved_args_size();
+        ctx[Arch::SP] = ctx[Arch::SP].wrapping_add(size as usize);
+    }
+
     pub fn unwind(&self, ctx: &Context) -> Result<Context, gimli::Error> {
         let row = &self.row;
         let mut new_ctx = ctx.clone();
@@ -139,6 +144,7 @@ impl Frame {
         new_ctx[Arch::SP] = cfa as _;
         new_ctx[Arch::RA] = 0;
 
+        #[warn(non_exhaustive_omitted_patterns)]
         for (reg, rule) in row.registers() {
             let value = match *rule {
                 RegisterRule::Undefined | RegisterRule::SameValue => ctx[*reg],
@@ -153,6 +159,8 @@ impl Frame {
                 }
                 RegisterRule::ValExpression(expr) => self.evaluate_expression(ctx, expr)?,
                 RegisterRule::Architectural => unreachable!(),
+                RegisterRule::Constant(value) => value as usize,
+                _ => unreachable!(),
             };
             new_ctx[*reg] = value;
         }

src/unwinder/mod.rs

@@ -13,6 +13,36 @@ use arch::*;
 use find_fde::FDEFinder;
 use frame::Frame;
 
+#[cfg(feature = "fde-custom")]
+pub use find_fde::custom_eh_frame_finder;
+
+// Helper function to turn `save_context` which takes function pointer to a closure-taking function.
+fn with_context<T, F: FnOnce(&mut Context) -> T>(f: F) -> T {
+    use core::mem::ManuallyDrop;
+
+    union Data<T, F> {
+        f: ManuallyDrop<F>,
+        t: ManuallyDrop<T>,
+    }
+
+    extern "C" fn delegate<T, F: FnOnce(&mut Context) -> T>(ctx: &mut Context, ptr: *mut ()) {
+        // SAFETY: This function is called exactly once; it extracts the function, call it and
+        // store the return value. This function is `extern "C"` so we don't need to worry about
+        // unwinding past it.
+        unsafe {
+            let data = &mut *ptr.cast::<Data<T, F>>();
+            let t = ManuallyDrop::take(&mut data.f)(ctx);
+            data.t = ManuallyDrop::new(t);
+        }
+    }
+
+    let mut data = Data {
+        f: ManuallyDrop::new(f),
+    };
+    save_context(delegate::<T, F>, ptr::addr_of_mut!(data).cast());
+    unsafe { ManuallyDrop::into_inner(data.t) }
+}
+
 #[repr(C)]
 pub struct UnwindException {
     pub exception_class: u64,
@@ -119,60 +149,63 @@ macro_rules! try2 {
 
 #[inline(never)]
 #[no_mangle]
-pub extern "C-unwind" fn _Unwind_RaiseException(
+pub unsafe extern "C-unwind" fn _Unwind_RaiseException(
-    exception: &mut UnwindException,
+    exception: *mut UnwindException,
 ) -> UnwindReasonCode {
-    let saved_ctx = save_context();
+    with_context(|saved_ctx| {
+        // Phase 1: Search for handler
+        let mut ctx = saved_ctx.clone();
+        let mut signal = false;
+        loop {
+            if let Some(frame) = try1!(Frame::from_context(&ctx, signal)) {
+                if let Some(personality) = frame.personality() {
+                    let result = unsafe {
+                        personality(
+                            1,
+                            UnwindAction::SEARCH_PHASE,
+                            (*exception).exception_class,
+                            exception,
+                            &mut UnwindContext {
+                                frame: Some(&frame),
+                                ctx: &mut ctx,
+                                signal,
+                            },
+                        )
+                    };
 
-    // Phase 1: Search for handler
+                    match result {
-    let mut ctx = saved_ctx.clone();
+                        UnwindReasonCode::CONTINUE_UNWIND => (),
-    let mut signal = false;
+                        UnwindReasonCode::HANDLER_FOUND => {
-    loop {
+                            break;
-        if let Some(frame) = try1!(Frame::from_context(&ctx, signal)) {
+                        }
-            if let Some(personality) = frame.personality() {
+                        _ => return UnwindReasonCode::FATAL_PHASE1_ERROR,
-                let result = personality(
-                    1,
-                    UnwindAction::SEARCH_PHASE,
-                    exception.exception_class,
-                    exception,
-                    &mut UnwindContext {
-                        frame: Some(&frame),
-                        ctx: &mut ctx,
-                        signal,
-                    },
-                );
-
-                match result {
-                    UnwindReasonCode::CONTINUE_UNWIND => (),
-                    UnwindReasonCode::HANDLER_FOUND => {
-                        break;
                     }
-                    _ => return UnwindReasonCode::FATAL_PHASE1_ERROR,
                 }
+
+                ctx = try1!(frame.unwind(&ctx));
+                signal = frame.is_signal_trampoline();
+            } else {
+                return UnwindReasonCode::END_OF_STACK;
             }
-
-            ctx = try1!(frame.unwind(&ctx));
-            signal = frame.is_signal_trampoline();
-        } else {
-            return UnwindReasonCode::END_OF_STACK;
         }
-    }
 
-    // Disambiguate normal frame and signal frame.
+        // Disambiguate normal frame and signal frame.
-    let handler_cfa = ctx[Arch::SP] - signal as usize;
+        let handler_cfa = ctx[Arch::SP] - signal as usize;
-    exception.private_1 = None;
+        unsafe {
-    exception.private_2 = handler_cfa;
+            (*exception).private_1 = None;
+            (*exception).private_2 = handler_cfa;
+        }
 
-    let mut ctx = saved_ctx;
+        let code = raise_exception_phase2(exception, saved_ctx, handler_cfa);
-    let code = raise_exception_phase2(exception, &mut ctx, handler_cfa);
+        match code {
-    match code {
+            UnwindReasonCode::INSTALL_CONTEXT => unsafe { restore_context(saved_ctx) },
-        UnwindReasonCode::INSTALL_CONTEXT => unsafe { restore_context(&ctx) },
+            _ => code,
-        _ => code,
+        }
-    }
+    })
 }
 
 fn raise_exception_phase2(
-    exception: &mut UnwindException,
+    exception: *mut UnwindException,
     ctx: &mut Context,
     handler_cfa: usize,
 ) -> UnwindReasonCode {
@@ -181,26 +214,31 @@ fn raise_exception_phase2(
         if let Some(frame) = try2!(Frame::from_context(ctx, signal)) {
             let frame_cfa = ctx[Arch::SP] - signal as usize;
             if let Some(personality) = frame.personality() {
-                let code = personality(
+                let code = unsafe {
-                    1,
+                    personality(
-                    UnwindAction::CLEANUP_PHASE
+                        1,
-                        | if frame_cfa == handler_cfa {
+                        UnwindAction::CLEANUP_PHASE
-                            UnwindAction::HANDLER_FRAME
+                            | if frame_cfa == handler_cfa {
-                        } else {
+                                UnwindAction::HANDLER_FRAME
-                            UnwindAction::empty()
+                            } else {
+                                UnwindAction::empty()
+                            },
+                        (*exception).exception_class,
+                        exception,
+                        &mut UnwindContext {
+                            frame: Some(&frame),
+                            ctx,
+                            signal,
                         },
-                    exception.exception_class,
+                    )
-                    exception,
+                };
-                    &mut UnwindContext {
-                        frame: Some(&frame),
-                        ctx,
-                        signal,
-                    },
-                );
 
                 match code {
                     UnwindReasonCode::CONTINUE_UNWIND => (),
-                    UnwindReasonCode::INSTALL_CONTEXT => break,
+                    UnwindReasonCode::INSTALL_CONTEXT => {
+                        frame.adjust_stack_for_args(ctx);
+                        return UnwindReasonCode::INSTALL_CONTEXT;
+                    }
                     _ => return UnwindReasonCode::FATAL_PHASE2_ERROR,
                 }
             }
@@ -211,31 +249,31 @@ fn raise_exception_phase2(
             return UnwindReasonCode::FATAL_PHASE2_ERROR;
         }
     }
-
-    UnwindReasonCode::INSTALL_CONTEXT
 }
 
 #[inline(never)]
 #[no_mangle]
-pub extern "C-unwind" fn _Unwind_ForcedUnwind(
+pub unsafe extern "C-unwind" fn _Unwind_ForcedUnwind(
-    exception: &mut UnwindException,
+    exception: *mut UnwindException,
     stop: UnwindStopFn,
     stop_arg: *mut c_void,
 ) -> UnwindReasonCode {
-    let mut ctx = save_context();
+    with_context(|ctx| {
+        unsafe {
+            (*exception).private_1 = Some(stop);
+            (*exception).private_2 = stop_arg as _;
+        }
 
-    exception.private_1 = Some(stop);
+        let code = force_unwind_phase2(exception, ctx, stop, stop_arg);
-    exception.private_2 = stop_arg as _;
+        match code {
-
+            UnwindReasonCode::INSTALL_CONTEXT => unsafe { restore_context(ctx) },
-    let code = force_unwind_phase2(exception, &mut ctx, stop, stop_arg);
+            _ => code,
-    match code {
+        }
-        UnwindReasonCode::INSTALL_CONTEXT => unsafe { restore_context(&ctx) },
+    })
-        _ => code,
-    }
 }
 
 fn force_unwind_phase2(
-    exception: &mut UnwindException,
+    exception: *mut UnwindException,
     ctx: &mut Context,
     stop: UnwindStopFn,
     stop_arg: *mut c_void,
@@ -244,24 +282,26 @@ fn force_unwind_phase2(
     loop {
         let frame = try2!(Frame::from_context(ctx, signal));
 
-        let code = stop(
+        let code = unsafe {
-            1,
+            stop(
-            UnwindAction::FORCE_UNWIND
+                1,
-                | UnwindAction::END_OF_STACK
+                UnwindAction::FORCE_UNWIND
-                | if frame.is_none() {
+                    | UnwindAction::END_OF_STACK
-                    UnwindAction::END_OF_STACK
+                    | if frame.is_none() {
-                } else {
+                        UnwindAction::END_OF_STACK
-                    UnwindAction::empty()
+                    } else {
+                        UnwindAction::empty()
+                    },
+                (*exception).exception_class,
+                exception,
+                &mut UnwindContext {
+                    frame: frame.as_ref(),
+                    ctx,
+                    signal,
                 },
-            exception.exception_class,
+                stop_arg,
-            exception,
+            )
-            &mut UnwindContext {
+        };
-                frame: frame.as_ref(),
-                ctx,
-                signal,
-            },
-            stop_arg,
-        );
         match code {
             UnwindReasonCode::NO_REASON => (),
             _ => return UnwindReasonCode::FATAL_PHASE2_ERROR,
@@ -269,21 +309,26 @@ fn force_unwind_phase2(
 
         if let Some(frame) = frame {
             if let Some(personality) = frame.personality() {
-                let code = personality(
+                let code = unsafe {
-                    1,
+                    personality(
-                    UnwindAction::FORCE_UNWIND | UnwindAction::CLEANUP_PHASE,
+                        1,
-                    exception.exception_class,
+                        UnwindAction::FORCE_UNWIND | UnwindAction::CLEANUP_PHASE,
-                    exception,
+                        (*exception).exception_class,
-                    &mut UnwindContext {
+                        exception,
-                        frame: Some(&frame),
+                        &mut UnwindContext {
-                        ctx,
+                            frame: Some(&frame),
-                        signal,
+                            ctx,
-                    },
+                            signal,
-                );
+                        },
+                    )
+                };
 
                 match code {
                     UnwindReasonCode::CONTINUE_UNWIND => (),
-                    UnwindReasonCode::INSTALL_CONTEXT => break,
+                    UnwindReasonCode::INSTALL_CONTEXT => {
+                        frame.adjust_stack_for_args(ctx);
+                        return UnwindReasonCode::INSTALL_CONTEXT;
+                    }
                     _ => return UnwindReasonCode::FATAL_PHASE2_ERROR,
                 }
             }
@@ -294,47 +339,45 @@ fn force_unwind_phase2(
             return UnwindReasonCode::END_OF_STACK;
         }
     }
-
-    UnwindReasonCode::INSTALL_CONTEXT
 }
 
 #[inline(never)]
 #[no_mangle]
-pub extern "C-unwind" fn _Unwind_Resume(exception: &mut UnwindException) -> ! {
+pub unsafe extern "C-unwind" fn _Unwind_Resume(exception: *mut UnwindException) -> ! {
-    let mut ctx = save_context();
+    with_context(|ctx| {
+        let code = match unsafe { (*exception).private_1 } {
+            None => {
+                let handler_cfa = unsafe { (*exception).private_2 };
+                raise_exception_phase2(exception, ctx, handler_cfa)
+            }
+            Some(stop) => {
+                let stop_arg = unsafe { (*exception).private_2 as _ };
+                force_unwind_phase2(exception, ctx, stop, stop_arg)
+            }
+        };
+        assert!(code == UnwindReasonCode::INSTALL_CONTEXT);
 
-    let code = match exception.private_1 {
+        unsafe { restore_context(ctx) }
-        None => {
+    })
-            let handler_cfa = exception.private_2;
-            raise_exception_phase2(exception, &mut ctx, handler_cfa)
-        }
-        Some(stop) => {
-            let stop_arg = exception.private_2 as _;
-            force_unwind_phase2(exception, &mut ctx, stop, stop_arg)
-        }
-    };
-    assert!(code == UnwindReasonCode::INSTALL_CONTEXT);
-
-    unsafe { restore_context(&ctx) }
 }
 
 #[inline(never)]
 #[no_mangle]
-pub extern "C-unwind" fn _Unwind_Resume_or_Rethrow(
+pub unsafe extern "C-unwind" fn _Unwind_Resume_or_Rethrow(
-    exception: &mut UnwindException,
+    exception: *mut UnwindException,
 ) -> UnwindReasonCode {
-    let stop = match exception.private_1 {
+    let stop = match unsafe { (*exception).private_1 } {
-        None => return _Unwind_RaiseException(exception),
+        None => return unsafe { _Unwind_RaiseException(exception) },
         Some(v) => v,
     };
 
-    let mut ctx = save_context();
+    with_context(|ctx| {
+        let stop_arg = unsafe { (*exception).private_2 as _ };
+        let code = force_unwind_phase2(exception, ctx, stop, stop_arg);
+        assert!(code == UnwindReasonCode::INSTALL_CONTEXT);
 
-    let stop_arg = exception.private_2 as _;
+        unsafe { restore_context(ctx) }
-    let code = force_unwind_phase2(exception, &mut ctx, stop, stop_arg);
+    })
-    assert!(code == UnwindReasonCode::INSTALL_CONTEXT);
-
-    unsafe { restore_context(&ctx) }
 }
 
 #[no_mangle]
@@ -350,36 +393,38 @@ pub extern "C-unwind" fn _Unwind_Backtrace(
     trace: UnwindTraceFn,
     trace_argument: *mut c_void,
 ) -> UnwindReasonCode {
-    let mut ctx = save_context();
+    with_context(|ctx| {
-    let mut signal = false;
+        let mut ctx = ctx.clone();
-    let mut skipping = cfg!(feature = "hide-trace");
+        let mut signal = false;
+        let mut skipping = cfg!(feature = "hide-trace");
 
-    loop {
+        loop {
-        let frame = try1!(Frame::from_context(&ctx, signal));
+            let frame = try1!(Frame::from_context(&ctx, signal));
-        if !skipping {
+            if !skipping {
-            let code = trace(
+                let code = trace(
-                &mut UnwindContext {
+                    &UnwindContext {
-                    frame: frame.as_ref(),
+                        frame: frame.as_ref(),
-                    ctx: &mut ctx,
+                        ctx: &mut ctx,
-                    signal,
+                        signal,
-                },
+                    },
-                trace_argument,
+                    trace_argument,
-            );
+                );
-            match code {
+                match code {
-                UnwindReasonCode::NO_REASON => (),
+                    UnwindReasonCode::NO_REASON => (),
-                _ => return UnwindReasonCode::FATAL_PHASE1_ERROR,
+                    _ => return UnwindReasonCode::FATAL_PHASE1_ERROR,
-            }
-        }
-        if let Some(frame) = frame {
-            if skipping {
-                if frame.initial_address() == _Unwind_Backtrace as usize {
-                    skipping = false;
                 }
             }
-            ctx = try1!(frame.unwind(&ctx));
+            if let Some(frame) = frame {
-            signal = frame.is_signal_trampoline();
+                if skipping {
-        } else {
+                    if frame.initial_address() == _Unwind_Backtrace as usize {
-            return UnwindReasonCode::END_OF_STACK;
+                        skipping = false;
+                    }
+                }
+                ctx = try1!(frame.unwind(&ctx));
+                signal = frame.is_signal_trampoline();
+            } else {
+                return UnwindReasonCode::END_OF_STACK;
+            }
         }
-    }
+    })
 }

src/util.rs

@@ -23,3 +23,19 @@ pub use libc::c_int;
 #[cfg(not(feature = "libc"))]
 #[allow(non_camel_case_types)]
 pub type c_int = i32;
+
+#[cfg(all(
+    any(feature = "panic", feature = "panic-handler-dummy"),
+    feature = "libc"
+))]
+pub fn abort() -> ! {
+    unsafe { libc::abort() };
+}
+
+#[cfg(all(
+    any(feature = "panic", feature = "panic-handler-dummy"),
+    not(feature = "libc")
+))]
+pub fn abort() -> ! {
+    core::intrinsics::abort();
+}

tests/compile_tests.rs

@@ -0,0 +1,20 @@
+use std::process::Command;
+
+#[test]
+fn main() {
+    let dir = env!("CARGO_MANIFEST_DIR");
+
+    let tests = [
+        "throw_and_catch",
+        "catch_std_exception",
+        "std_catch_exception",
+    ];
+
+    for test in tests {
+        let status = Command::new("./check.sh")
+            .current_dir(format!("{dir}/test_crates/{test}"))
+            .status()
+            .unwrap();
+        assert!(status.success());
+    }
+}