| // Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! Backtrace support using libunwind/gcc_s/etc APIs. |
| //! |
| //! This module contains the ability to unwind the stack using libunwind-style |
| //! APIs. Note that there's a whole bunch of implementations of the |
| //! libunwind-like API, and this is just trying to be compatible with most of |
| //! them all at once instead of being picky. |
| //! |
| //! The libunwind API is powered by `_Unwind_Backtrace` and is in practice very |
| //! reliable at generating a backtrace. It's not entirely clear how it does it |
| //! (frame pointers? eh_frame info? both?) but it seems to work! |
| //! |
| //! Most of the complexity of this module is handling the various platform |
| //! differences across libunwind implementations. Otherwise this is a pretty |
| //! straightforward Rust binding to the libunwind APIs. |
| //! |
| //! This is the default unwinding API for all non-Windows platforms currently. |
| |
| use core::ffi::c_void; |
| |
| pub enum Frame { |
| Raw(*mut uw::_Unwind_Context), |
| Cloned { |
| ip: *mut c_void, |
| symbol_address: *mut c_void, |
| }, |
| } |
| |
| // With a raw libunwind pointer it should only ever be access in a readonly |
| // threadsafe fashion, so it's `Sync`. When sending to other threads via `Clone` |
| // we always switch to a version which doesn't retain interior pointers, so we |
| // should be `Send` as well. |
| unsafe impl Send for Frame {} |
| unsafe impl Sync for Frame {} |
| |
| impl Frame { |
| pub fn ip(&self) -> *mut c_void { |
| let ctx = match *self { |
| Frame::Raw(ctx) => ctx, |
| Frame::Cloned { ip, .. } => return ip, |
| }; |
| unsafe { uw::_Unwind_GetIP(ctx) as *mut c_void } |
| } |
| |
| pub fn symbol_address(&self) -> *mut c_void { |
| if let Frame::Cloned { symbol_address, .. } = *self { |
| return symbol_address; |
| } |
| |
| // It seems that on OSX `_Unwind_FindEnclosingFunction` returns a |
| // pointer to... something that's unclear. It's definitely not always |
| // the enclosing function for whatever reason. It's not entirely clear |
| // to me what's going on here, so pessimize this for now and just always |
| // return the ip. |
| // |
| // Note the `skip_inner_frames.rs` test is skipped on OSX due to this |
| // clause, and if this is fixed that test in theory can be run on OSX! |
| if cfg!(target_os = "macos") || cfg!(target_os = "ios") { |
| self.ip() |
| } else { |
| unsafe { uw::_Unwind_FindEnclosingFunction(self.ip()) } |
| } |
| } |
| } |
| |
| impl Clone for Frame { |
| fn clone(&self) -> Frame { |
| Frame::Cloned { |
| ip: self.ip(), |
| symbol_address: self.symbol_address(), |
| } |
| } |
| } |
| |
| #[inline(always)] |
| pub unsafe fn trace(mut cb: &mut FnMut(&super::Frame) -> bool) { |
| uw::_Unwind_Backtrace(trace_fn, &mut cb as *mut _ as *mut _); |
| |
| extern "C" fn trace_fn( |
| ctx: *mut uw::_Unwind_Context, |
| arg: *mut c_void, |
| ) -> uw::_Unwind_Reason_Code { |
| let cb = unsafe { &mut *(arg as *mut &mut FnMut(&super::Frame) -> bool) }; |
| let cx = super::Frame { |
| inner: Frame::Raw(ctx), |
| }; |
| |
| let mut bomb = crate::Bomb { enabled: true }; |
| let keep_going = cb(&cx); |
| bomb.enabled = false; |
| |
| if keep_going { |
| uw::_URC_NO_REASON |
| } else { |
| uw::_URC_FAILURE |
| } |
| } |
| } |
| |
| /// Unwind library interface used for backtraces |
| /// |
| /// Note that dead code is allowed as here are just bindings |
| /// iOS doesn't use all of them it but adding more |
| /// platform-specific configs pollutes the code too much |
| #[allow(non_camel_case_types)] |
| #[allow(non_snake_case)] |
| #[allow(dead_code)] |
| mod uw { |
| pub use self::_Unwind_Reason_Code::*; |
| |
| use core::ffi::c_void; |
| |
| #[repr(C)] |
| pub enum _Unwind_Reason_Code { |
| _URC_NO_REASON = 0, |
| _URC_FOREIGN_EXCEPTION_CAUGHT = 1, |
| _URC_FATAL_PHASE2_ERROR = 2, |
| _URC_FATAL_PHASE1_ERROR = 3, |
| _URC_NORMAL_STOP = 4, |
| _URC_END_OF_STACK = 5, |
| _URC_HANDLER_FOUND = 6, |
| _URC_INSTALL_CONTEXT = 7, |
| _URC_CONTINUE_UNWIND = 8, |
| _URC_FAILURE = 9, // used only by ARM EABI |
| } |
| |
| pub enum _Unwind_Context {} |
| |
| pub type _Unwind_Trace_Fn = |
| extern "C" fn(ctx: *mut _Unwind_Context, arg: *mut c_void) -> _Unwind_Reason_Code; |
| |
| extern "C" { |
| // No native _Unwind_Backtrace on iOS |
| #[cfg(not(all(target_os = "ios", target_arch = "arm")))] |
| pub fn _Unwind_Backtrace( |
| trace: _Unwind_Trace_Fn, |
| trace_argument: *mut c_void, |
| ) -> _Unwind_Reason_Code; |
| |
| // available since GCC 4.2.0, should be fine for our purpose |
| #[cfg(all( |
| not(all(target_os = "android", target_arch = "arm")), |
| not(all(target_os = "freebsd", target_arch = "arm")), |
| not(all(target_os = "linux", target_arch = "arm")) |
| ))] |
| pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t; |
| |
| #[cfg(all( |
| not(target_os = "android"), |
| not(all(target_os = "freebsd", target_arch = "arm")), |
| not(all(target_os = "linux", target_arch = "arm")) |
| ))] |
| pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void; |
| } |
| |
| // On android, the function _Unwind_GetIP is a macro, and this is the |
| // expansion of the macro. This is all copy/pasted directly from the |
| // header file with the definition of _Unwind_GetIP. |
| #[cfg(any( |
| all(target_os = "android", target_arch = "arm"), |
| all(target_os = "freebsd", target_arch = "arm"), |
| all(target_os = "linux", target_arch = "arm") |
| ))] |
| pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t { |
| #[repr(C)] |
| enum _Unwind_VRS_Result { |
| _UVRSR_OK = 0, |
| _UVRSR_NOT_IMPLEMENTED = 1, |
| _UVRSR_FAILED = 2, |
| } |
| #[repr(C)] |
| enum _Unwind_VRS_RegClass { |
| _UVRSC_CORE = 0, |
| _UVRSC_VFP = 1, |
| _UVRSC_FPA = 2, |
| _UVRSC_WMMXD = 3, |
| _UVRSC_WMMXC = 4, |
| } |
| #[repr(C)] |
| enum _Unwind_VRS_DataRepresentation { |
| _UVRSD_UINT32 = 0, |
| _UVRSD_VFPX = 1, |
| _UVRSD_FPAX = 2, |
| _UVRSD_UINT64 = 3, |
| _UVRSD_FLOAT = 4, |
| _UVRSD_DOUBLE = 5, |
| } |
| |
| type _Unwind_Word = libc::c_uint; |
| extern "C" { |
| fn _Unwind_VRS_Get( |
| ctx: *mut _Unwind_Context, |
| klass: _Unwind_VRS_RegClass, |
| word: _Unwind_Word, |
| repr: _Unwind_VRS_DataRepresentation, |
| data: *mut c_void, |
| ) -> _Unwind_VRS_Result; |
| } |
| |
| let mut val: _Unwind_Word = 0; |
| let ptr = &mut val as *mut _Unwind_Word; |
| let _ = _Unwind_VRS_Get( |
| ctx, |
| _Unwind_VRS_RegClass::_UVRSC_CORE, |
| 15, |
| _Unwind_VRS_DataRepresentation::_UVRSD_UINT32, |
| ptr as *mut c_void, |
| ); |
| (val & !1) as libc::uintptr_t |
| } |
| |
| // This function also doesn't exist on Android or ARM/Linux, so make it |
| // a no-op |
| #[cfg(any( |
| target_os = "android", |
| all(target_os = "freebsd", target_arch = "arm"), |
| all(target_os = "linux", target_arch = "arm") |
| ))] |
| pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void { |
| pc |
| } |
| } |
