// binaries, but it should never be called as we don't link in an unwinding
// runtime at all.
pub mod personalities {
- #[rustc_std_internal_symbol]
- #[cfg(not(any(
- all(target_family = "wasm", not(target_os = "emscripten")),
- all(target_os = "windows", target_env = "gnu", target_arch = "x86_64",),
- )))]
- pub extern "C" fn rust_eh_personality() {}
-
- // On x86_64-pc-windows-gnu we use our own personality function that needs
- // to return `ExceptionContinueSearch` as we're passing on all our frames.
- #[rustc_std_internal_symbol]
- #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86_64"))]
- pub extern "C" fn rust_eh_personality(
- _record: usize,
- _frame: usize,
- _context: usize,
- _dispatcher: usize,
- ) -> u32 {
- 1 // `ExceptionContinueSearch`
- }
-
// Similar to above, this corresponds to the `eh_catch_typeinfo` lang item
// that's only used on Emscripten currently.
//
+++ /dev/null
-//! Parsing of GCC-style Language-Specific Data Area (LSDA)
-//! For details see:
-//! * <https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA/ehframechpt.html>
-//! * <https://itanium-cxx-abi.github.io/cxx-abi/exceptions.pdf>
-//! * <https://www.airs.com/blog/archives/460>
-//! * <https://www.airs.com/blog/archives/464>
-//!
-//! A reference implementation may be found in the GCC source tree
-//! (`<root>/libgcc/unwind-c.c` as of this writing).
-
-#![allow(non_upper_case_globals)]
-#![allow(unused)]
-
-use crate::dwarf::DwarfReader;
-use core::mem;
-
-pub const DW_EH_PE_omit: u8 = 0xFF;
-pub const DW_EH_PE_absptr: u8 = 0x00;
-
-pub const DW_EH_PE_uleb128: u8 = 0x01;
-pub const DW_EH_PE_udata2: u8 = 0x02;
-pub const DW_EH_PE_udata4: u8 = 0x03;
-pub const DW_EH_PE_udata8: u8 = 0x04;
-pub const DW_EH_PE_sleb128: u8 = 0x09;
-pub const DW_EH_PE_sdata2: u8 = 0x0A;
-pub const DW_EH_PE_sdata4: u8 = 0x0B;
-pub const DW_EH_PE_sdata8: u8 = 0x0C;
-
-pub const DW_EH_PE_pcrel: u8 = 0x10;
-pub const DW_EH_PE_textrel: u8 = 0x20;
-pub const DW_EH_PE_datarel: u8 = 0x30;
-pub const DW_EH_PE_funcrel: u8 = 0x40;
-pub const DW_EH_PE_aligned: u8 = 0x50;
-
-pub const DW_EH_PE_indirect: u8 = 0x80;
-
-#[derive(Copy, Clone)]
-pub struct EHContext<'a> {
- pub ip: usize, // Current instruction pointer
- pub func_start: usize, // Address of the current function
- pub get_text_start: &'a dyn Fn() -> usize, // Get address of the code section
- pub get_data_start: &'a dyn Fn() -> usize, // Get address of the data section
-}
-
-pub enum EHAction {
- None,
- Cleanup(usize),
- Catch(usize),
- Terminate,
-}
-
-pub const USING_SJLJ_EXCEPTIONS: bool = cfg!(all(target_os = "ios", target_arch = "arm"));
-
-pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result<EHAction, ()> {
- if lsda.is_null() {
- return Ok(EHAction::None);
- }
-
- let func_start = context.func_start;
- let mut reader = DwarfReader::new(lsda);
-
- let start_encoding = reader.read::<u8>();
- // base address for landing pad offsets
- let lpad_base = if start_encoding != DW_EH_PE_omit {
- read_encoded_pointer(&mut reader, context, start_encoding)?
- } else {
- func_start
- };
-
- let ttype_encoding = reader.read::<u8>();
- if ttype_encoding != DW_EH_PE_omit {
- // Rust doesn't analyze exception types, so we don't care about the type table
- reader.read_uleb128();
- }
-
- let call_site_encoding = reader.read::<u8>();
- let call_site_table_length = reader.read_uleb128();
- let action_table = reader.ptr.add(call_site_table_length as usize);
- let ip = context.ip;
-
- if !USING_SJLJ_EXCEPTIONS {
- while reader.ptr < action_table {
- let cs_start = read_encoded_pointer(&mut reader, context, call_site_encoding)?;
- let cs_len = read_encoded_pointer(&mut reader, context, call_site_encoding)?;
- let cs_lpad = read_encoded_pointer(&mut reader, context, call_site_encoding)?;
- let cs_action = reader.read_uleb128();
- // Callsite table is sorted by cs_start, so if we've passed the ip, we
- // may stop searching.
- if ip < func_start + cs_start {
- break;
- }
- if ip < func_start + cs_start + cs_len {
- if cs_lpad == 0 {
- return Ok(EHAction::None);
- } else {
- let lpad = lpad_base + cs_lpad;
- return Ok(interpret_cs_action(cs_action, lpad));
- }
- }
- }
- // Ip is not present in the table. This should not happen... but it does: issue #35011.
- // So rather than returning EHAction::Terminate, we do this.
- Ok(EHAction::None)
- } else {
- // SjLj version:
- // The "IP" is an index into the call-site table, with two exceptions:
- // -1 means 'no-action', and 0 means 'terminate'.
- match ip as isize {
- -1 => return Ok(EHAction::None),
- 0 => return Ok(EHAction::Terminate),
- _ => (),
- }
- let mut idx = ip;
- loop {
- let cs_lpad = reader.read_uleb128();
- let cs_action = reader.read_uleb128();
- idx -= 1;
- if idx == 0 {
- // Can never have null landing pad for sjlj -- that would have
- // been indicated by a -1 call site index.
- let lpad = (cs_lpad + 1) as usize;
- return Ok(interpret_cs_action(cs_action, lpad));
- }
- }
- }
-}
-
-fn interpret_cs_action(cs_action: u64, lpad: usize) -> EHAction {
- if cs_action == 0 {
- // If cs_action is 0 then this is a cleanup (Drop::drop). We run these
- // for both Rust panics and foreign exceptions.
- EHAction::Cleanup(lpad)
- } else {
- // Stop unwinding Rust panics at catch_unwind.
- EHAction::Catch(lpad)
- }
-}
-
-#[inline]
-fn round_up(unrounded: usize, align: usize) -> Result<usize, ()> {
- if align.is_power_of_two() { Ok((unrounded + align - 1) & !(align - 1)) } else { Err(()) }
-}
-
-unsafe fn read_encoded_pointer(
- reader: &mut DwarfReader,
- context: &EHContext<'_>,
- encoding: u8,
-) -> Result<usize, ()> {
- if encoding == DW_EH_PE_omit {
- return Err(());
- }
-
- // DW_EH_PE_aligned implies it's an absolute pointer value
- if encoding == DW_EH_PE_aligned {
- reader.ptr = round_up(reader.ptr as usize, mem::size_of::<usize>())? as *const u8;
- return Ok(reader.read::<usize>());
- }
-
- let mut result = match encoding & 0x0F {
- DW_EH_PE_absptr => reader.read::<usize>(),
- DW_EH_PE_uleb128 => reader.read_uleb128() as usize,
- DW_EH_PE_udata2 => reader.read::<u16>() as usize,
- DW_EH_PE_udata4 => reader.read::<u32>() as usize,
- DW_EH_PE_udata8 => reader.read::<u64>() as usize,
- DW_EH_PE_sleb128 => reader.read_sleb128() as usize,
- DW_EH_PE_sdata2 => reader.read::<i16>() as usize,
- DW_EH_PE_sdata4 => reader.read::<i32>() as usize,
- DW_EH_PE_sdata8 => reader.read::<i64>() as usize,
- _ => return Err(()),
- };
-
- result += match encoding & 0x70 {
- DW_EH_PE_absptr => 0,
- // relative to address of the encoded value, despite the name
- DW_EH_PE_pcrel => reader.ptr as usize,
- DW_EH_PE_funcrel => {
- if context.func_start == 0 {
- return Err(());
- }
- context.func_start
- }
- DW_EH_PE_textrel => (*context.get_text_start)(),
- DW_EH_PE_datarel => (*context.get_data_start)(),
- _ => return Err(()),
- };
-
- if encoding & DW_EH_PE_indirect != 0 {
- result = *(result as *const usize);
- }
-
- Ok(result)
-}
+++ /dev/null
-//! Utilities for parsing DWARF-encoded data streams.
-//! See <http://www.dwarfstd.org>,
-//! DWARF-4 standard, Section 7 - "Data Representation"
-
-// This module is used only by x86_64-pc-windows-gnu for now, but we
-// are compiling it everywhere to avoid regressions.
-#![allow(unused)]
-
-#[cfg(test)]
-mod tests;
-
-pub mod eh;
-
-use core::mem;
-
-pub struct DwarfReader {
- pub ptr: *const u8,
-}
-
-#[repr(C, packed)]
-struct Unaligned<T>(T);
-
-impl DwarfReader {
- pub fn new(ptr: *const u8) -> DwarfReader {
- DwarfReader { ptr }
- }
-
- // DWARF streams are packed, so e.g., a u32 would not necessarily be aligned
- // on a 4-byte boundary. This may cause problems on platforms with strict
- // alignment requirements. By wrapping data in a "packed" struct, we are
- // telling the backend to generate "misalignment-safe" code.
- pub unsafe fn read<T: Copy>(&mut self) -> T {
- let Unaligned(result) = *(self.ptr as *const Unaligned<T>);
- self.ptr = self.ptr.add(mem::size_of::<T>());
- result
- }
-
- // ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable
- // Length Data".
- pub unsafe fn read_uleb128(&mut self) -> u64 {
- let mut shift: usize = 0;
- let mut result: u64 = 0;
- let mut byte: u8;
- loop {
- byte = self.read::<u8>();
- result |= ((byte & 0x7F) as u64) << shift;
- shift += 7;
- if byte & 0x80 == 0 {
- break;
- }
- }
- result
- }
-
- pub unsafe fn read_sleb128(&mut self) -> i64 {
- let mut shift: u32 = 0;
- let mut result: u64 = 0;
- let mut byte: u8;
- loop {
- byte = self.read::<u8>();
- result |= ((byte & 0x7F) as u64) << shift;
- shift += 7;
- if byte & 0x80 == 0 {
- break;
- }
- }
- // sign-extend
- if shift < u64::BITS && (byte & 0x40) != 0 {
- result |= (!0 as u64) << shift;
- }
- result as i64
- }
-}
+++ /dev/null
-use super::*;
-
-#[test]
-fn dwarf_reader() {
- let encoded: &[u8] = &[1, 2, 3, 4, 5, 6, 7, 0xE5, 0x8E, 0x26, 0x9B, 0xF1, 0x59, 0xFF, 0xFF];
-
- let mut reader = DwarfReader::new(encoded.as_ptr());
-
- unsafe {
- assert!(reader.read::<u8>() == u8::to_be(1u8));
- assert!(reader.read::<u16>() == u16::to_be(0x0203));
- assert!(reader.read::<u32>() == u32::to_be(0x04050607));
-
- assert!(reader.read_uleb128() == 624485);
- assert!(reader.read_sleb128() == -624485);
-
- assert!(reader.read::<i8>() == i8::to_be(-1));
- }
-}
use core::mem;
use core::ptr;
use core::sync::atomic::{AtomicBool, Ordering};
-use libc::{self, c_int};
use unwind as uw;
// This matches the layout of std::type_info in C++
}
}
-// This is required by the compiler to exist (e.g., it's a lang item), but it's
-// never actually called by the compiler. Emscripten EH doesn't use a
-// personality function at all, it instead uses __cxa_find_matching_catch.
-// Wasm error handling would use __gxx_personality_wasm0.
-#[lang = "eh_personality"]
-unsafe extern "C" fn rust_eh_personality(
- _version: c_int,
- _actions: uw::_Unwind_Action,
- _exception_class: uw::_Unwind_Exception_Class,
- _exception_object: *mut uw::_Unwind_Exception,
- _context: *mut uw::_Unwind_Context,
-) -> uw::_Unwind_Reason_Code {
- core::intrinsics::abort()
-}
-
extern "C" {
fn __cxa_allocate_exception(thrown_size: libc::size_t) -> *mut libc::c_void;
fn __cxa_begin_catch(thrown_exception: *mut libc::c_void) -> *mut libc::c_void;
use alloc::boxed::Box;
use core::any::Any;
-use crate::dwarf::eh::{self, EHAction, EHContext};
-use libc::{c_int, uintptr_t};
use unwind as uw;
#[repr(C)]
0x4d4f5a_00_52555354
}
-// Register ids were lifted from LLVM's TargetLowering::getExceptionPointerRegister()
-// and TargetLowering::getExceptionSelectorRegister() for each architecture,
-// then mapped to DWARF register numbers via register definition tables
-// (typically <arch>RegisterInfo.td, search for "DwarfRegNum").
-// See also https://llvm.org/docs/WritingAnLLVMBackend.html#defining-a-register.
-
-#[cfg(target_arch = "x86")]
-const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
-
-#[cfg(target_arch = "x86_64")]
-const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
-
-#[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
-const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 / X0, X1
-
-#[cfg(target_arch = "m68k")]
-const UNWIND_DATA_REG: (i32, i32) = (0, 1); // D0, D1
-
-#[cfg(any(target_arch = "mips", target_arch = "mips64"))]
-const UNWIND_DATA_REG: (i32, i32) = (4, 5); // A0, A1
-
-#[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
-const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 / X3, X4
-
-#[cfg(target_arch = "s390x")]
-const UNWIND_DATA_REG: (i32, i32) = (6, 7); // R6, R7
-
-#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
-const UNWIND_DATA_REG: (i32, i32) = (24, 25); // I0, I1
-
-#[cfg(target_arch = "hexagon")]
-const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1
-
-#[cfg(any(target_arch = "riscv64", target_arch = "riscv32"))]
-const UNWIND_DATA_REG: (i32, i32) = (10, 11); // x10, x11
-
-// The following code is based on GCC's C and C++ personality routines. For reference, see:
-// https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
-// https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c
-
-cfg_if::cfg_if! {
- if #[cfg(all(target_arch = "arm", not(target_os = "ios"), not(target_os = "watchos"), not(target_os = "netbsd")))] {
- // ARM EHABI personality routine.
- // https://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf
- //
- // iOS uses the default routine instead since it uses SjLj unwinding.
- #[lang = "eh_personality"]
- unsafe extern "C" fn rust_eh_personality(state: uw::_Unwind_State,
- exception_object: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- let state = state as c_int;
- let action = state & uw::_US_ACTION_MASK as c_int;
- let search_phase = if action == uw::_US_VIRTUAL_UNWIND_FRAME as c_int {
- // Backtraces on ARM will call the personality routine with
- // state == _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND. In those cases
- // we want to continue unwinding the stack, otherwise all our backtraces
- // would end at __rust_try
- if state & uw::_US_FORCE_UNWIND as c_int != 0 {
- return continue_unwind(exception_object, context);
- }
- true
- } else if action == uw::_US_UNWIND_FRAME_STARTING as c_int {
- false
- } else if action == uw::_US_UNWIND_FRAME_RESUME as c_int {
- return continue_unwind(exception_object, context);
- } else {
- return uw::_URC_FAILURE;
- };
-
- // The DWARF unwinder assumes that _Unwind_Context holds things like the function
- // and LSDA pointers, however ARM EHABI places them into the exception object.
- // To preserve signatures of functions like _Unwind_GetLanguageSpecificData(), which
- // take only the context pointer, GCC personality routines stash a pointer to
- // exception_object in the context, using location reserved for ARM's
- // "scratch register" (r12).
- uw::_Unwind_SetGR(context,
- uw::UNWIND_POINTER_REG,
- exception_object as uw::_Unwind_Ptr);
- // ...A more principled approach would be to provide the full definition of ARM's
- // _Unwind_Context in our libunwind bindings and fetch the required data from there
- // directly, bypassing DWARF compatibility functions.
-
- let eh_action = match find_eh_action(context) {
- Ok(action) => action,
- Err(_) => return uw::_URC_FAILURE,
- };
- if search_phase {
- match eh_action {
- EHAction::None |
- EHAction::Cleanup(_) => return continue_unwind(exception_object, context),
- EHAction::Catch(_) => {
- // EHABI requires the personality routine to update the
- // SP value in the barrier cache of the exception object.
- (*exception_object).private[5] =
- uw::_Unwind_GetGR(context, uw::UNWIND_SP_REG);
- return uw::_URC_HANDLER_FOUND;
- }
- EHAction::Terminate => return uw::_URC_FAILURE,
- }
- } else {
- match eh_action {
- EHAction::None => return continue_unwind(exception_object, context),
- EHAction::Cleanup(lpad) |
- EHAction::Catch(lpad) => {
- uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0,
- exception_object as uintptr_t);
- uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
- uw::_Unwind_SetIP(context, lpad);
- return uw::_URC_INSTALL_CONTEXT;
- }
- EHAction::Terminate => return uw::_URC_FAILURE,
- }
- }
-
- // On ARM EHABI the personality routine is responsible for actually
- // unwinding a single stack frame before returning (ARM EHABI Sec. 6.1).
- unsafe fn continue_unwind(exception_object: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- if __gnu_unwind_frame(exception_object, context) == uw::_URC_NO_REASON {
- uw::_URC_CONTINUE_UNWIND
- } else {
- uw::_URC_FAILURE
- }
- }
- // defined in libgcc
- extern "C" {
- fn __gnu_unwind_frame(exception_object: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code;
- }
- }
- } else {
- // Default personality routine, which is used directly on most targets
- // and indirectly on Windows x86_64 via SEH.
- unsafe extern "C" fn rust_eh_personality_impl(version: c_int,
- actions: uw::_Unwind_Action,
- _exception_class: uw::_Unwind_Exception_Class,
- exception_object: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- if version != 1 {
- return uw::_URC_FATAL_PHASE1_ERROR;
- }
- let eh_action = match find_eh_action(context) {
- Ok(action) => action,
- Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
- };
- if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
- match eh_action {
- EHAction::None |
- EHAction::Cleanup(_) => uw::_URC_CONTINUE_UNWIND,
- EHAction::Catch(_) => uw::_URC_HANDLER_FOUND,
- EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR,
- }
- } else {
- match eh_action {
- EHAction::None => uw::_URC_CONTINUE_UNWIND,
- EHAction::Cleanup(lpad) |
- EHAction::Catch(lpad) => {
- uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0,
- exception_object as uintptr_t);
- uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
- uw::_Unwind_SetIP(context, lpad);
- uw::_URC_INSTALL_CONTEXT
- }
- EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR,
- }
- }
- }
-
- cfg_if::cfg_if! {
- if #[cfg(all(windows, target_arch = "x86_64", target_env = "gnu"))] {
- // On x86_64 MinGW targets, the unwinding mechanism is SEH however the unwind
- // handler data (aka LSDA) uses GCC-compatible encoding.
- #[lang = "eh_personality"]
- #[allow(nonstandard_style)]
- unsafe extern "C" fn rust_eh_personality(exceptionRecord: *mut uw::EXCEPTION_RECORD,
- establisherFrame: uw::LPVOID,
- contextRecord: *mut uw::CONTEXT,
- dispatcherContext: *mut uw::DISPATCHER_CONTEXT)
- -> uw::EXCEPTION_DISPOSITION {
- uw::_GCC_specific_handler(exceptionRecord,
- establisherFrame,
- contextRecord,
- dispatcherContext,
- rust_eh_personality_impl)
- }
- } else {
- // The personality routine for most of our targets.
- #[lang = "eh_personality"]
- unsafe extern "C" fn rust_eh_personality(version: c_int,
- actions: uw::_Unwind_Action,
- exception_class: uw::_Unwind_Exception_Class,
- exception_object: *mut uw::_Unwind_Exception,
- context: *mut uw::_Unwind_Context)
- -> uw::_Unwind_Reason_Code {
- rust_eh_personality_impl(version,
- actions,
- exception_class,
- exception_object,
- context)
- }
- }
- }
- }
-}
-
-unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> Result<EHAction, ()> {
- let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
- let mut ip_before_instr: c_int = 0;
- let ip = uw::_Unwind_GetIPInfo(context, &mut ip_before_instr);
- let eh_context = EHContext {
- // The return address points 1 byte past the call instruction,
- // which could be in the next IP range in LSDA range table.
- //
- // `ip = -1` has special meaning, so use wrapping sub to allow for that
- ip: if ip_before_instr != 0 { ip } else { ip.wrapping_sub(1) },
- func_start: uw::_Unwind_GetRegionStart(context),
- get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
- get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
- };
- eh::find_eh_action(lsda, &eh_context)
-}
-
// Frame unwind info registration
//
// Each module's image contains a frame unwind info section (usually
fn __rust_foreign_exception() -> !;
}
-mod dwarf;
-
#[rustc_std_internal_symbol]
#[allow(improper_ctypes_definitions)]
pub unsafe extern "C" fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any + Send + 'static) {
exception.data.take().unwrap()
}
}
-
-// This is required by the compiler to exist (e.g., it's a lang item), but
-// it's never actually called by the compiler because _CxxFrameHandler3
-// is the personality function that is always used.
-// Hence this is just an aborting stub.
-#[lang = "eh_personality"]
-#[cfg(not(test))]
-fn rust_eh_personality() {
- core::intrinsics::abort()
-}
// Private support modules
mod panicking;
+mod personality;
#[path = "../../backtrace/src/lib.rs"]
#[allow(dead_code, unused_attributes)]
--- /dev/null
+//! This module contains the implementation of the `eh_personality` lang item.
+//!
+//! The actual implementation is heavily dependent on the target since Rust
+//! tries to use the native stack unwinding mechanism whenever possible.
+//!
+//! This personality function is still required with `-C panic=abort` because
+//! it is used to catch foreign exceptions from `extern "C-unwind"` and turn
+//! them into aborts.
+//!
+//! Additionally, ARM EHABI uses the personality function when generating
+//! backtraces.
+
+mod dwarf;
+
+#[cfg(not(test))]
+cfg_if::cfg_if! {
+ if #[cfg(target_os = "emscripten")] {
+ mod emcc;
+ } else if #[cfg(target_env = "msvc")] {
+ // This is required by the compiler to exist (e.g., it's a lang item),
+ // but it's never actually called by the compiler because
+ // _CxxFrameHandler3 is the personality function that is always used.
+ // Hence this is just an aborting stub.
+ #[lang = "eh_personality"]
+ fn rust_eh_personality() {
+ core::intrinsics::abort()
+ }
+ } else if #[cfg(any(
+ all(target_family = "windows", target_env = "gnu"),
+ target_os = "psp",
+ target_os = "solid_asp3",
+ all(target_family = "unix", not(target_os = "espidf")),
+ all(target_vendor = "fortanix", target_env = "sgx"),
+ ))] {
+ mod gcc;
+ } else {
+ // Targets that don't support unwinding.
+ // - family=wasm
+ // - os=none ("bare metal" targets)
+ // - os=uefi
+ // - os=espidf
+ // - os=hermit
+ // - nvptx64-nvidia-cuda
+ // - arch=avr
+ }
+}
--- /dev/null
+//! Parsing of GCC-style Language-Specific Data Area (LSDA)
+//! For details see:
+//! * <https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA/ehframechpt.html>
+//! * <https://itanium-cxx-abi.github.io/cxx-abi/exceptions.pdf>
+//! * <https://www.airs.com/blog/archives/460>
+//! * <https://www.airs.com/blog/archives/464>
+//!
+//! A reference implementation may be found in the GCC source tree
+//! (`<root>/libgcc/unwind-c.c` as of this writing).
+
+#![allow(non_upper_case_globals)]
+#![allow(unused)]
+
+use super::DwarfReader;
+use core::mem;
+
+pub const DW_EH_PE_omit: u8 = 0xFF;
+pub const DW_EH_PE_absptr: u8 = 0x00;
+
+pub const DW_EH_PE_uleb128: u8 = 0x01;
+pub const DW_EH_PE_udata2: u8 = 0x02;
+pub const DW_EH_PE_udata4: u8 = 0x03;
+pub const DW_EH_PE_udata8: u8 = 0x04;
+pub const DW_EH_PE_sleb128: u8 = 0x09;
+pub const DW_EH_PE_sdata2: u8 = 0x0A;
+pub const DW_EH_PE_sdata4: u8 = 0x0B;
+pub const DW_EH_PE_sdata8: u8 = 0x0C;
+
+pub const DW_EH_PE_pcrel: u8 = 0x10;
+pub const DW_EH_PE_textrel: u8 = 0x20;
+pub const DW_EH_PE_datarel: u8 = 0x30;
+pub const DW_EH_PE_funcrel: u8 = 0x40;
+pub const DW_EH_PE_aligned: u8 = 0x50;
+
+pub const DW_EH_PE_indirect: u8 = 0x80;
+
+#[derive(Copy, Clone)]
+pub struct EHContext<'a> {
+ pub ip: usize, // Current instruction pointer
+ pub func_start: usize, // Address of the current function
+ pub get_text_start: &'a dyn Fn() -> usize, // Get address of the code section
+ pub get_data_start: &'a dyn Fn() -> usize, // Get address of the data section
+}
+
+pub enum EHAction {
+ None,
+ Cleanup(usize),
+ Catch(usize),
+ Terminate,
+}
+
+pub const USING_SJLJ_EXCEPTIONS: bool = cfg!(all(target_os = "ios", target_arch = "arm"));
+
+pub unsafe fn find_eh_action(lsda: *const u8, context: &EHContext<'_>) -> Result<EHAction, ()> {
+ if lsda.is_null() {
+ return Ok(EHAction::None);
+ }
+
+ let func_start = context.func_start;
+ let mut reader = DwarfReader::new(lsda);
+
+ let start_encoding = reader.read::<u8>();
+ // base address for landing pad offsets
+ let lpad_base = if start_encoding != DW_EH_PE_omit {
+ read_encoded_pointer(&mut reader, context, start_encoding)?
+ } else {
+ func_start
+ };
+
+ let ttype_encoding = reader.read::<u8>();
+ if ttype_encoding != DW_EH_PE_omit {
+ // Rust doesn't analyze exception types, so we don't care about the type table
+ reader.read_uleb128();
+ }
+
+ let call_site_encoding = reader.read::<u8>();
+ let call_site_table_length = reader.read_uleb128();
+ let action_table = reader.ptr.add(call_site_table_length as usize);
+ let ip = context.ip;
+
+ if !USING_SJLJ_EXCEPTIONS {
+ while reader.ptr < action_table {
+ let cs_start = read_encoded_pointer(&mut reader, context, call_site_encoding)?;
+ let cs_len = read_encoded_pointer(&mut reader, context, call_site_encoding)?;
+ let cs_lpad = read_encoded_pointer(&mut reader, context, call_site_encoding)?;
+ let cs_action = reader.read_uleb128();
+ // Callsite table is sorted by cs_start, so if we've passed the ip, we
+ // may stop searching.
+ if ip < func_start + cs_start {
+ break;
+ }
+ if ip < func_start + cs_start + cs_len {
+ if cs_lpad == 0 {
+ return Ok(EHAction::None);
+ } else {
+ let lpad = lpad_base + cs_lpad;
+ return Ok(interpret_cs_action(cs_action, lpad));
+ }
+ }
+ }
+ // Ip is not present in the table. This should not happen... but it does: issue #35011.
+ // So rather than returning EHAction::Terminate, we do this.
+ Ok(EHAction::None)
+ } else {
+ // SjLj version:
+ // The "IP" is an index into the call-site table, with two exceptions:
+ // -1 means 'no-action', and 0 means 'terminate'.
+ match ip as isize {
+ -1 => return Ok(EHAction::None),
+ 0 => return Ok(EHAction::Terminate),
+ _ => (),
+ }
+ let mut idx = ip;
+ loop {
+ let cs_lpad = reader.read_uleb128();
+ let cs_action = reader.read_uleb128();
+ idx -= 1;
+ if idx == 0 {
+ // Can never have null landing pad for sjlj -- that would have
+ // been indicated by a -1 call site index.
+ let lpad = (cs_lpad + 1) as usize;
+ return Ok(interpret_cs_action(cs_action, lpad));
+ }
+ }
+ }
+}
+
+fn interpret_cs_action(cs_action: u64, lpad: usize) -> EHAction {
+ if cs_action == 0 {
+ // If cs_action is 0 then this is a cleanup (Drop::drop). We run these
+ // for both Rust panics and foreign exceptions.
+ EHAction::Cleanup(lpad)
+ } else {
+ // Stop unwinding Rust panics at catch_unwind.
+ EHAction::Catch(lpad)
+ }
+}
+
+#[inline]
+fn round_up(unrounded: usize, align: usize) -> Result<usize, ()> {
+ if align.is_power_of_two() { Ok((unrounded + align - 1) & !(align - 1)) } else { Err(()) }
+}
+
+unsafe fn read_encoded_pointer(
+ reader: &mut DwarfReader,
+ context: &EHContext<'_>,
+ encoding: u8,
+) -> Result<usize, ()> {
+ if encoding == DW_EH_PE_omit {
+ return Err(());
+ }
+
+ // DW_EH_PE_aligned implies it's an absolute pointer value
+ if encoding == DW_EH_PE_aligned {
+ reader.ptr = round_up(reader.ptr as usize, mem::size_of::<usize>())? as *const u8;
+ return Ok(reader.read::<usize>());
+ }
+
+ let mut result = match encoding & 0x0F {
+ DW_EH_PE_absptr => reader.read::<usize>(),
+ DW_EH_PE_uleb128 => reader.read_uleb128() as usize,
+ DW_EH_PE_udata2 => reader.read::<u16>() as usize,
+ DW_EH_PE_udata4 => reader.read::<u32>() as usize,
+ DW_EH_PE_udata8 => reader.read::<u64>() as usize,
+ DW_EH_PE_sleb128 => reader.read_sleb128() as usize,
+ DW_EH_PE_sdata2 => reader.read::<i16>() as usize,
+ DW_EH_PE_sdata4 => reader.read::<i32>() as usize,
+ DW_EH_PE_sdata8 => reader.read::<i64>() as usize,
+ _ => return Err(()),
+ };
+
+ result += match encoding & 0x70 {
+ DW_EH_PE_absptr => 0,
+ // relative to address of the encoded value, despite the name
+ DW_EH_PE_pcrel => reader.ptr as usize,
+ DW_EH_PE_funcrel => {
+ if context.func_start == 0 {
+ return Err(());
+ }
+ context.func_start
+ }
+ DW_EH_PE_textrel => (*context.get_text_start)(),
+ DW_EH_PE_datarel => (*context.get_data_start)(),
+ _ => return Err(()),
+ };
+
+ if encoding & DW_EH_PE_indirect != 0 {
+ result = *(result as *const usize);
+ }
+
+ Ok(result)
+}
--- /dev/null
+//! Utilities for parsing DWARF-encoded data streams.
+//! See <http://www.dwarfstd.org>,
+//! DWARF-4 standard, Section 7 - "Data Representation"
+
+// This module is used only by x86_64-pc-windows-gnu for now, but we
+// are compiling it everywhere to avoid regressions.
+#![allow(unused)]
+
+#[cfg(test)]
+mod tests;
+
+pub mod eh;
+
+use core::mem;
+
+pub struct DwarfReader {
+ pub ptr: *const u8,
+}
+
+#[repr(C, packed)]
+struct Unaligned<T>(T);
+
+impl DwarfReader {
+ pub fn new(ptr: *const u8) -> DwarfReader {
+ DwarfReader { ptr }
+ }
+
+ // DWARF streams are packed, so e.g., a u32 would not necessarily be aligned
+ // on a 4-byte boundary. This may cause problems on platforms with strict
+ // alignment requirements. By wrapping data in a "packed" struct, we are
+ // telling the backend to generate "misalignment-safe" code.
+ pub unsafe fn read<T: Copy>(&mut self) -> T {
+ let Unaligned(result) = *(self.ptr as *const Unaligned<T>);
+ self.ptr = self.ptr.add(mem::size_of::<T>());
+ result
+ }
+
+ // ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable
+ // Length Data".
+ pub unsafe fn read_uleb128(&mut self) -> u64 {
+ let mut shift: usize = 0;
+ let mut result: u64 = 0;
+ let mut byte: u8;
+ loop {
+ byte = self.read::<u8>();
+ result |= ((byte & 0x7F) as u64) << shift;
+ shift += 7;
+ if byte & 0x80 == 0 {
+ break;
+ }
+ }
+ result
+ }
+
+ pub unsafe fn read_sleb128(&mut self) -> i64 {
+ let mut shift: u32 = 0;
+ let mut result: u64 = 0;
+ let mut byte: u8;
+ loop {
+ byte = self.read::<u8>();
+ result |= ((byte & 0x7F) as u64) << shift;
+ shift += 7;
+ if byte & 0x80 == 0 {
+ break;
+ }
+ }
+ // sign-extend
+ if shift < u64::BITS && (byte & 0x40) != 0 {
+ result |= (!0 as u64) << shift;
+ }
+ result as i64
+ }
+}
--- /dev/null
+use super::*;
+
+#[test]
+fn dwarf_reader() {
+ let encoded: &[u8] = &[1, 2, 3, 4, 5, 6, 7, 0xE5, 0x8E, 0x26, 0x9B, 0xF1, 0x59, 0xFF, 0xFF];
+
+ let mut reader = DwarfReader::new(encoded.as_ptr());
+
+ unsafe {
+ assert!(reader.read::<u8>() == u8::to_be(1u8));
+ assert!(reader.read::<u16>() == u16::to_be(0x0203));
+ assert!(reader.read::<u32>() == u32::to_be(0x04050607));
+
+ assert!(reader.read_uleb128() == 624485);
+ assert!(reader.read_sleb128() == -624485);
+
+ assert!(reader.read::<i8>() == i8::to_be(-1));
+ }
+}
--- /dev/null
+//! On Emscripten Rust panics are wrapped in C++ exceptions, so we just forward
+//! to `__gxx_personality_v0` which is provided by Emscripten.
+
+use libc::c_int;
+use unwind as uw;
+
+// This is required by the compiler to exist (e.g., it's a lang item), but it's
+// never actually called by the compiler. Emscripten EH doesn't use a
+// personality function at all, it instead uses __cxa_find_matching_catch.
+// Wasm error handling would use __gxx_personality_wasm0.
+#[lang = "eh_personality"]
+unsafe extern "C" fn rust_eh_personality(
+ _version: c_int,
+ _actions: uw::_Unwind_Action,
+ _exception_class: uw::_Unwind_Exception_Class,
+ _exception_object: *mut uw::_Unwind_Exception,
+ _context: *mut uw::_Unwind_Context,
+) -> uw::_Unwind_Reason_Code {
+ core::intrinsics::abort()
+}
--- /dev/null
+//! Implementation of panics backed by libgcc/libunwind (in some form).
+//!
+//! For background on exception handling and stack unwinding please see
+//! "Exception Handling in LLVM" (llvm.org/docs/ExceptionHandling.html) and
+//! documents linked from it.
+//! These are also good reads:
+//! * <https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html>
+//! * <https://monoinfinito.wordpress.com/series/exception-handling-in-c/>
+//! * <https://www.airs.com/blog/index.php?s=exception+frames>
+//!
+//! ## A brief summary
+//!
+//! Exception handling happens in two phases: a search phase and a cleanup
+//! phase.
+//!
+//! In both phases the unwinder walks stack frames from top to bottom using
+//! information from the stack frame unwind sections of the current process's
+//! modules ("module" here refers to an OS module, i.e., an executable or a
+//! dynamic library).
+//!
+//! For each stack frame, it invokes the associated "personality routine", whose
+//! address is also stored in the unwind info section.
+//!
+//! In the search phase, the job of a personality routine is to examine
+//! exception object being thrown, and to decide whether it should be caught at
+//! that stack frame. Once the handler frame has been identified, cleanup phase
+//! begins.
+//!
+//! In the cleanup phase, the unwinder invokes each personality routine again.
+//! This time it decides which (if any) cleanup code needs to be run for
+//! the current stack frame. If so, the control is transferred to a special
+//! branch in the function body, the "landing pad", which invokes destructors,
+//! frees memory, etc. At the end of the landing pad, control is transferred
+//! back to the unwinder and unwinding resumes.
+//!
+//! Once stack has been unwound down to the handler frame level, unwinding stops
+//! and the last personality routine transfers control to the catch block.
+
+use super::dwarf::eh::{self, EHAction, EHContext};
+use libc::{c_int, uintptr_t};
+use unwind as uw;
+
+// Register ids were lifted from LLVM's TargetLowering::getExceptionPointerRegister()
+// and TargetLowering::getExceptionSelectorRegister() for each architecture,
+// then mapped to DWARF register numbers via register definition tables
+// (typically <arch>RegisterInfo.td, search for "DwarfRegNum").
+// See also https://llvm.org/docs/WritingAnLLVMBackend.html#defining-a-register.
+
+#[cfg(target_arch = "x86")]
+const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
+
+#[cfg(target_arch = "x86_64")]
+const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
+
+#[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
+const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1 / X0, X1
+
+#[cfg(target_arch = "m68k")]
+const UNWIND_DATA_REG: (i32, i32) = (0, 1); // D0, D1
+
+#[cfg(any(target_arch = "mips", target_arch = "mips64"))]
+const UNWIND_DATA_REG: (i32, i32) = (4, 5); // A0, A1
+
+#[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
+const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 / X3, X4
+
+#[cfg(target_arch = "s390x")]
+const UNWIND_DATA_REG: (i32, i32) = (6, 7); // R6, R7
+
+#[cfg(any(target_arch = "sparc", target_arch = "sparc64"))]
+const UNWIND_DATA_REG: (i32, i32) = (24, 25); // I0, I1
+
+#[cfg(target_arch = "hexagon")]
+const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1
+
+#[cfg(any(target_arch = "riscv64", target_arch = "riscv32"))]
+const UNWIND_DATA_REG: (i32, i32) = (10, 11); // x10, x11
+
+// The following code is based on GCC's C and C++ personality routines. For reference, see:
+// https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
+// https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c
+
+cfg_if::cfg_if! {
+ if #[cfg(all(target_arch = "arm", not(target_os = "ios"), not(target_os = "watchos"), not(target_os = "netbsd")))] {
+ // ARM EHABI personality routine.
+ // https://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf
+ //
+ // iOS uses the default routine instead since it uses SjLj unwinding.
+ #[lang = "eh_personality"]
+ unsafe extern "C" fn rust_eh_personality(
+ state: uw::_Unwind_State,
+ exception_object: *mut uw::_Unwind_Exception,
+ context: *mut uw::_Unwind_Context,
+ ) -> uw::_Unwind_Reason_Code {
+ let state = state as c_int;
+ let action = state & uw::_US_ACTION_MASK as c_int;
+ let search_phase = if action == uw::_US_VIRTUAL_UNWIND_FRAME as c_int {
+ // Backtraces on ARM will call the personality routine with
+ // state == _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND. In those cases
+ // we want to continue unwinding the stack, otherwise all our backtraces
+ // would end at __rust_try
+ if state & uw::_US_FORCE_UNWIND as c_int != 0 {
+ return continue_unwind(exception_object, context);
+ }
+ true
+ } else if action == uw::_US_UNWIND_FRAME_STARTING as c_int {
+ false
+ } else if action == uw::_US_UNWIND_FRAME_RESUME as c_int {
+ return continue_unwind(exception_object, context);
+ } else {
+ return uw::_URC_FAILURE;
+ };
+
+ // The DWARF unwinder assumes that _Unwind_Context holds things like the function
+ // and LSDA pointers, however ARM EHABI places them into the exception object.
+ // To preserve signatures of functions like _Unwind_GetLanguageSpecificData(), which
+ // take only the context pointer, GCC personality routines stash a pointer to
+ // exception_object in the context, using location reserved for ARM's
+ // "scratch register" (r12).
+ uw::_Unwind_SetGR(context, uw::UNWIND_POINTER_REG, exception_object as uw::_Unwind_Ptr);
+ // ...A more principled approach would be to provide the full definition of ARM's
+ // _Unwind_Context in our libunwind bindings and fetch the required data from there
+ // directly, bypassing DWARF compatibility functions.
+
+ let eh_action = match find_eh_action(context) {
+ Ok(action) => action,
+ Err(_) => return uw::_URC_FAILURE,
+ };
+ if search_phase {
+ match eh_action {
+ EHAction::None | EHAction::Cleanup(_) => {
+ return continue_unwind(exception_object, context);
+ }
+ EHAction::Catch(_) => {
+ // EHABI requires the personality routine to update the
+ // SP value in the barrier cache of the exception object.
+ (*exception_object).private[5] =
+ uw::_Unwind_GetGR(context, uw::UNWIND_SP_REG);
+ return uw::_URC_HANDLER_FOUND;
+ }
+ EHAction::Terminate => return uw::_URC_FAILURE,
+ }
+ } else {
+ match eh_action {
+ EHAction::None => return continue_unwind(exception_object, context),
+ EHAction::Cleanup(lpad) | EHAction::Catch(lpad) => {
+ uw::_Unwind_SetGR(
+ context,
+ UNWIND_DATA_REG.0,
+ exception_object as uintptr_t,
+ );
+ uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
+ uw::_Unwind_SetIP(context, lpad);
+ return uw::_URC_INSTALL_CONTEXT;
+ }
+ EHAction::Terminate => return uw::_URC_FAILURE,
+ }
+ }
+
+ // On ARM EHABI the personality routine is responsible for actually
+ // unwinding a single stack frame before returning (ARM EHABI Sec. 6.1).
+ unsafe fn continue_unwind(
+ exception_object: *mut uw::_Unwind_Exception,
+ context: *mut uw::_Unwind_Context,
+ ) -> uw::_Unwind_Reason_Code {
+ if __gnu_unwind_frame(exception_object, context) == uw::_URC_NO_REASON {
+ uw::_URC_CONTINUE_UNWIND
+ } else {
+ uw::_URC_FAILURE
+ }
+ }
+ // defined in libgcc
+ extern "C" {
+ fn __gnu_unwind_frame(
+ exception_object: *mut uw::_Unwind_Exception,
+ context: *mut uw::_Unwind_Context,
+ ) -> uw::_Unwind_Reason_Code;
+ }
+ }
+ } else {
+ // Default personality routine, which is used directly on most targets
+ // and indirectly on Windows x86_64 via SEH.
+ unsafe extern "C" fn rust_eh_personality_impl(
+ version: c_int,
+ actions: uw::_Unwind_Action,
+ _exception_class: uw::_Unwind_Exception_Class,
+ exception_object: *mut uw::_Unwind_Exception,
+ context: *mut uw::_Unwind_Context,
+ ) -> uw::_Unwind_Reason_Code {
+ if version != 1 {
+ return uw::_URC_FATAL_PHASE1_ERROR;
+ }
+ let eh_action = match find_eh_action(context) {
+ Ok(action) => action,
+ Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
+ };
+ if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
+ match eh_action {
+ EHAction::None | EHAction::Cleanup(_) => uw::_URC_CONTINUE_UNWIND,
+ EHAction::Catch(_) => uw::_URC_HANDLER_FOUND,
+ EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR,
+ }
+ } else {
+ match eh_action {
+ EHAction::None => uw::_URC_CONTINUE_UNWIND,
+ EHAction::Cleanup(lpad) | EHAction::Catch(lpad) => {
+ uw::_Unwind_SetGR(
+ context,
+ UNWIND_DATA_REG.0,
+ exception_object as uintptr_t,
+ );
+ uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
+ uw::_Unwind_SetIP(context, lpad);
+ uw::_URC_INSTALL_CONTEXT
+ }
+ EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR,
+ }
+ }
+ }
+
+ cfg_if::cfg_if! {
+ if #[cfg(all(windows, target_arch = "x86_64", target_env = "gnu"))] {
+ // On x86_64 MinGW targets, the unwinding mechanism is SEH however the unwind
+ // handler data (aka LSDA) uses GCC-compatible encoding.
+ #[lang = "eh_personality"]
+ #[allow(nonstandard_style)]
+ unsafe extern "C" fn rust_eh_personality(
+ exceptionRecord: *mut uw::EXCEPTION_RECORD,
+ establisherFrame: uw::LPVOID,
+ contextRecord: *mut uw::CONTEXT,
+ dispatcherContext: *mut uw::DISPATCHER_CONTEXT,
+ ) -> uw::EXCEPTION_DISPOSITION {
+ uw::_GCC_specific_handler(
+ exceptionRecord,
+ establisherFrame,
+ contextRecord,
+ dispatcherContext,
+ rust_eh_personality_impl,
+ )
+ }
+ } else {
+ // The personality routine for most of our targets.
+ #[lang = "eh_personality"]
+ unsafe extern "C" fn rust_eh_personality(
+ version: c_int,
+ actions: uw::_Unwind_Action,
+ exception_class: uw::_Unwind_Exception_Class,
+ exception_object: *mut uw::_Unwind_Exception,
+ context: *mut uw::_Unwind_Context,
+ ) -> uw::_Unwind_Reason_Code {
+ rust_eh_personality_impl(
+ version,
+ actions,
+ exception_class,
+ exception_object,
+ context,
+ )
+ }
+ }
+ }
+ }
+}
+
+unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> Result<EHAction, ()> {
+ let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
+ let mut ip_before_instr: c_int = 0;
+ let ip = uw::_Unwind_GetIPInfo(context, &mut ip_before_instr);
+ let eh_context = EHContext {
+ // The return address points 1 byte past the call instruction,
+ // which could be in the next IP range in LSDA range table.
+ //
+ // `ip = -1` has special meaning, so use wrapping sub to allow for that
+ ip: if ip_before_instr != 0 { ip } else { ip.wrapping_sub(1) },
+ func_start: uw::_Unwind_GetRegionStart(context),
+ get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
+ get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
+ };
+ eh::find_eh_action(lsda, &eh_context)
+}
projects / rust.git / commitdiff