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Implement rust_eh_personality in Rust, remove rust_eh_personality_catch.

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Well, not quite: ARM EHABI platforms still use the old scheme -- for now.
This commit is contained in:
Vadim Chugunov 2016-07-22 14:57:54 -07:00
parent 3cc3ad11e6
commit 051c2d14fb
6 changed files with 177 additions and 139 deletions
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169
src/libpanic_unwind/gcc.rs
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@ -106,117 +106,96 @@ fn rust_exception_class() -> uw::_Unwind_Exception_Class {
0x4d4f5a_00_52555354
}
// We could implement our personality routine in Rust, however exception
// info decoding is tedious. More importantly, personality routines have to
// handle various platform quirks, which are not fun to maintain. For this
// reason, we attempt to reuse personality routine of the C language:
// __gcc_personality_v0.
//
// Since C does not support exception catching, __gcc_personality_v0 simply
// always returns _URC_CONTINUE_UNWIND in search phase, and always returns
// _URC_INSTALL_CONTEXT (i.e. "invoke cleanup code") in cleanup phase.
//
// This is pretty close to Rust's exception handling approach, except that Rust
// does have a single "catch-all" handler at the bottom of each thread's stack.
// So we have two versions of the personality routine:
// - rust_eh_personality, used by all cleanup landing pads, which never catches,
// so the behavior of __gcc_personality_v0 is perfectly adequate there, and
// - rust_eh_personality_catch, used only by rust_try(), which always catches.
//
// See also: rustc_trans::trans::intrinsic::trans_gnu_try
#[cfg(all(not(target_arch = "arm"),
not(all(windows, target_arch = "x86_64"))))]
// All targets, except ARM which uses a slightly different ABI (however, iOS goes here as it uses
// SjLj unwinding). Also, 64-bit Windows implementation lives in seh64_gnu.rs
#[cfg(all(any(target_os = "ios", not(target_arch = "arm"))))]
pub mod eabi {
use unwind as uw;
use libc::c_int;
use libc::{c_int, uintptr_t};
use dwarf::eh::{EHContext, EHAction, find_eh_action};
extern "C" {
fn __gcc_personality_v0(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code;
}
// 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 http://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(any(target_arch = "mips", target_arch = "mipsel"))]
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
// 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
#[lang = "eh_personality"]
#[no_mangle]
extern "C" fn rust_eh_personality(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
unsafe { __gcc_personality_v0(version, actions, exception_class, ue_header, context) }
}
#[allow(unused)]
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 {
if version != 1 {
return uw::_URC_FATAL_PHASE1_ERROR;
}
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: if ip_before_instr != 0 { ip } else { ip - 1 },
func_start: uw::_Unwind_GetRegionStart(context),
get_text_start: &|| uw::_Unwind_GetTextRelBase(context),
get_data_start: &|| uw::_Unwind_GetDataRelBase(context),
};
let eh_action = find_eh_action(lsda, &eh_context);
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern "C" fn rust_eh_personality_catch(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 {
// search phase
uw::_URC_HANDLER_FOUND // catch!
if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
match eh_action {
EHAction::None | EHAction::Cleanup(_) => return uw::_URC_CONTINUE_UNWIND,
EHAction::Catch(_) => return uw::_URC_HANDLER_FOUND,
EHAction::Terminate => return uw::_URC_FATAL_PHASE1_ERROR,
}
} else {
// cleanup phase
unsafe { __gcc_personality_v0(version, actions, exception_class, ue_header, context) }
match eh_action {
EHAction::None => return 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);
return uw::_URC_INSTALL_CONTEXT;
}
EHAction::Terminate => return uw::_URC_FATAL_PHASE2_ERROR,
}
}
}
}
// iOS on armv7 is using SjLj exceptions and therefore requires to use
// a specialized personality routine: __gcc_personality_sj0
#[cfg(all(target_os = "ios", target_arch = "arm"))]
pub mod eabi {
use unwind as uw;
use libc::c_int;
extern "C" {
fn __gcc_personality_sj0(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code;
}
#[lang = "eh_personality"]
#[no_mangle]
pub extern "C" fn rust_eh_personality(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
unsafe { __gcc_personality_sj0(version, actions, exception_class, ue_header, context) }
}
#[cfg(stage0)]
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern "C" fn rust_eh_personality_catch(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 {
// search phase
uw::_URC_HANDLER_FOUND // catch!
} else {
// cleanup phase
unsafe { __gcc_personality_sj0(version, actions, exception_class, ue_header, context) }
}
pub unsafe extern "C" fn rust_eh_personality_catch(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
rust_eh_personality(version, actions, exception_class, ue_header, context)
}
}
// ARM EHABI uses a slightly different personality routine signature,
// but otherwise works the same.
#[cfg(all(target_arch = "arm", not(target_os = "ios")))]