mirror of https://github.com/m-labs/artiq
95 lines
4.2 KiB
Rust
95 lines
4.2 KiB
Rust
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// This is the Rust personality function, adapted for use in ARTIQ. We never actually panic
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// from Rust or recover from Rust exceptions (there's nothing to catch the panics), but we
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// need a personality function to step back through Rust frames in order to make a backtrace.
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//
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// By design, this personality function is only ever called in the search phase, although
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// to keep things simple and close to upstream, it is not modified
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use unwind as uw;
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use libc::{c_int, uintptr_t};
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use dwarf::{self, EHAction, EHContext};
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// Register ids were lifted from LLVM's TargetLowering::getExceptionPointerRegister()
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// and TargetLowering::getExceptionSelectorRegister() for each architecture,
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// then mapped to DWARF register numbers via register definition tables
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// (typically <arch>RegisterInfo.td, search for "DwarfRegNum").
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// See also http://llvm.org/docs/WritingAnLLVMBackend.html#defining-a-register.
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#[cfg(target_arch = "x86")]
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const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
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#[cfg(target_arch = "x86_64")]
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const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
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#[cfg(any(target_arch = "or1k"))]
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const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4
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#[cfg(any(target_arch = "riscv32"))]
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const UNWIND_DATA_REG: (i32, i32) = (10, 11); // X10, X11
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// The following code is based on GCC's C and C++ personality routines. For reference, see:
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// https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
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// https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c
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#[lang = "eh_personality"]
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#[no_mangle]
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#[allow(unused)]
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unsafe extern "C" fn rust_eh_personality(version: c_int,
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actions: uw::_Unwind_Action,
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exception_class: uw::_Unwind_Exception_Class,
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context)
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-> uw::_Unwind_Reason_Code {
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if version != 1 {
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return uw::_URC_FATAL_PHASE1_ERROR;
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}
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let eh_action = match find_eh_action(context) {
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Ok(action) => action,
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Err(_) => return uw::_URC_FATAL_PHASE1_ERROR,
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};
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if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
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match eh_action {
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EHAction::None |
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EHAction::Cleanup(_) => return uw::_URC_CONTINUE_UNWIND,
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EHAction::Catch(_) => return uw::_URC_HANDLER_FOUND,
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EHAction::Terminate => return uw::_URC_FATAL_PHASE1_ERROR,
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}
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} else {
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match eh_action {
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EHAction::None => return uw::_URC_CONTINUE_UNWIND,
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EHAction::Cleanup(lpad) |
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EHAction::Catch(lpad) => {
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0, exception_object as uintptr_t);
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
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uw::_Unwind_SetIP(context, lpad);
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return uw::_URC_INSTALL_CONTEXT;
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}
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EHAction::Terminate => return uw::_URC_FATAL_PHASE2_ERROR,
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}
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}
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}
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unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> Result<EHAction, ()> {
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let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
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let mut ip_before_instr: c_int = 0;
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let ip = uw::_Unwind_GetIPInfo(context, &mut ip_before_instr);
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let eh_context = EHContext {
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// The return address points 1 byte past the call instruction,
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// which could be in the next IP range in LSDA range table.
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ip: if ip_before_instr != 0 { ip } else { ip - 1 },
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func_start: uw::_Unwind_GetRegionStart(context),
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get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
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get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
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};
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dwarf::find_eh_action(lsda, &eh_context)
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}
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