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Implement ARM personality routine in Rust.

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Remove the `eh_personality_catch` lang item.
Use a simplified version of `cfg_if!` in libunwind.
This commit is contained in:
Vadim Chugunov 2016-07-23 17:25:25 -07:00
parent 2c50f4e484
commit 6cef93d400
5 changed files with 339 additions and 295 deletions
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291
src/libpanic_unwind/gcc.rs
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@ -61,6 +61,8 @@ use core::ptr;
use alloc::boxed::Box;
use unwind as uw;
use libc::{c_int, uintptr_t};
use dwarf::eh::{self, EHContext, EHAction};
#[repr(C)]
struct Exception {
@ -106,139 +108,184 @@ fn rust_exception_class() -> uw::_Unwind_Exception_Class {
0x4d4f5a_00_52555354
}
// 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
// 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
// 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
// The personality routine for most of our targets, except ARM, which has a slightly different ABI
// (however, iOS goes here as it uses SjLj unwinding). Also, the 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, uintptr_t};
use dwarf::eh::{EHContext, EHAction, find_eh_action};
// 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]
#[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);
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 {
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,
}
}
#[lang = "eh_personality"]
#[no_mangle]
#[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;
}
#[cfg(stage0)]
#[lang = "eh_personality_catch"]
#[no_mangle]
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)
let eh_action = find_eh_action(context);
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 {
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,
}
}
}
// ARM EHABI uses a slightly different personality routine signature,
// but otherwise works the same.
// ARM EHABI personality routine.
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf
#[cfg(all(target_arch = "arm", not(target_os = "ios")))]
pub mod eabi {
use unwind as uw;
use libc::c_int;
extern "C" {
fn __gcc_personality_v0(state: uw::_Unwind_State,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code;
}
#[lang = "eh_personality"]
#[no_mangle]
extern "C" fn rust_eh_personality(state: uw::_Unwind_State,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
unsafe { __gcc_personality_v0(state, ue_header, context) }
}
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern "C" fn rust_eh_personality_catch(state: uw::_Unwind_State,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
#[lang = "eh_personality"]
#[no_mangle]
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 as c_int & uw::_US_ACTION_MASK as c_int) ==
uw::_US_VIRTUAL_UNWIND_FRAME as c_int &&
(state as c_int & uw::_US_FORCE_UNWIND as c_int) == 0 {
// search phase
uw::_URC_HANDLER_FOUND // catch!
} else {
// cleanup phase
unsafe { __gcc_personality_v0(state, ue_header, context) }
// 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 = find_eh_action(context);
if search_phase {
match eh_action {
EHAction::None |
EHAction::Cleanup(_) => return continue_unwind(exception_object, context),
EHAction::Catch(_) => 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;
}
}
unsafe fn find_eh_action(context: *mut uw::_Unwind_Context) -> 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: 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),
};
eh::find_eh_action(lsda, &eh_context)
}
// *** Delete after a new snapshot ***
#[cfg(all(stage0, any(target_os = "ios", not(target_arch = "arm"))))]
#[lang = "eh_personality_catch"]
#[no_mangle]
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)
}
// *** Delete after a new snapshot ***
#[cfg(all(stage0, target_arch = "arm", not(target_os = "ios")))]
#[lang = "eh_personality_catch"]
#[no_mangle]
pub unsafe extern "C" fn rust_eh_personality_catch(state: uw::_Unwind_State,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
rust_eh_personality(state, ue_header, context)
}
// See docs in the `unwind` module.