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Exception handling: patched exception handling for ARTIQ.

core0-buffer
pca006132 2 years ago
parent
commit
eb750eb1f0
  1. 2
      src/armv7-none-eabihf.json
  2. 253
      src/runtime/src/eh_artiq.rs
  3. 16
      src/runtime/src/kernel.rs
  4. 1
      src/runtime/src/main.rs

2
src/armv7-none-eabihf.json

@ -20,6 +20,8 @@
"max-atomic-width": 32,
"os": "none",
"panic-strategy": "abort",
"requires-uwtable": true,
"force-unwind-tables": "yes",
"relocation-model": "static",
"target-c-int-width": "32",
"target-endian": "little",

253
src/runtime/src/eh_artiq.rs

@ -1,3 +1,5 @@
// From Current artiq firmware ksupport implementation.
// Modified to suit the case of artiq-zynq port, for ARM EHABI.
// Portions of the code in this file are derived from code by:
//
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
@ -8,27 +10,21 @@
// <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.
#![allow(private_no_mangle_fns, non_camel_case_types)]
#![allow(non_camel_case_types)]
use core::{ptr, mem};
use core::mem;
use cslice::CSlice;
use unwind as uw;
use libc::{c_int, c_void};
use eh::dwarf::{self, EHAction};
type _Unwind_Stop_Fn = extern "C" fn(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
exception_object: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context,
stop_parameter: *mut c_void)
-> uw::_Unwind_Reason_Code;
extern {
fn _Unwind_ForcedUnwind(exception: *mut uw::_Unwind_Exception,
stop_fn: _Unwind_Stop_Fn,
stop_parameter: *mut c_void) -> uw::_Unwind_Reason_Code;
}
use libc::{c_int, uintptr_t};
use log::debug;
use dwarf::eh::{self, EHAction, EHContext};
const EXCEPTION_CLASS: uw::_Unwind_Exception_Class = 0x4d_4c_42_53_41_52_54_51; /* 'MLBSARTQ' */
#[cfg(target_arch = "arm")]
const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1
#[repr(C)]
#[derive(Clone, Copy)]
@ -42,8 +38,6 @@ pub struct Exception<'a> {
pub param: [i64; 3]
}
const EXCEPTION_CLASS: uw::_Unwind_Exception_Class = 0x4d_4c_42_53_41_52_54_51; /* 'MLBSARTQ' */
const MAX_BACKTRACE_SIZE: usize = 128;
#[repr(C)]
@ -55,61 +49,113 @@ struct ExceptionInfo {
backtrace_size: usize
}
#[cfg(target_arch = "x86_64")]
const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
#[cfg(any(target_arch = "or1k"))]
const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4
unsafe fn find_eh_action(
context: *mut uw::_Unwind_Context,
foreign_exception: bool,
) -> 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: 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, foreign_exception)
}
#[export_name="__artiq_personality"]
pub extern fn personality(version: c_int,
actions: uw::_Unwind_Action,
uw_exception_class: uw::_Unwind_Exception_Class,
uw_exception: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code {
unsafe {
if version != 1 || uw_exception_class != EXCEPTION_CLASS {
return uw::_URC_FATAL_PHASE1_ERROR
pub unsafe fn artiq_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);
}
let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
let ip = uw::_Unwind_GetIP(context) - 1;
let func_start = uw::_Unwind_GetRegionStart(context);
let exception_info = &mut *(uw_exception as *mut ExceptionInfo);
let exception = &exception_info.exception.unwrap();
let eh_action = dwarf::find_eh_action(lsda, func_start, ip, exception.name);
if actions as u32 & uw::_UA_SEARCH_PHASE as u32 != 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,
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 exception_class = (*exception_object).exception_class;
let foreign_exception = exception_class != EXCEPTION_CLASS;
let eh_action = match find_eh_action(context, foreign_exception) {
Ok(action) => action,
Err(_) => return uw::_URC_FAILURE,
};
let exception_info = &mut *(exception_object as *mut ExceptionInfo);
let exception = &exception_info.exception.unwrap();
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;
}
} else {
match eh_action {
EHAction::None => return uw::_URC_CONTINUE_UNWIND,
EHAction::Cleanup(lpad) |
EHAction::Catch(lpad) => {
if actions as u32 & uw::_UA_HANDLER_FRAME as u32 != 0 {
exception_info.handled = true
}
// Pass a pair of the unwinder exception and ARTIQ exception
// (which immediately follows).
uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0,
uw_exception as uw::_Unwind_Word);
uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1,
exception as *const _ as uw::_Unwind_Word);
uw::_Unwind_SetIP(context, lpad);
return uw::_URC_INSTALL_CONTEXT;
}
EHAction::Terminate => return uw::_URC_FATAL_PHASE2_ERROR,
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, exception as *const _ as uw::_Unwind_Word);
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;
}
}
extern fn cleanup(_unwind_code: uw::_Unwind_Reason_Code,
@ -121,33 +167,6 @@ extern fn cleanup(_unwind_code: uw::_Unwind_Reason_Code,
}
}
extern fn uncaught_exception(_version: c_int,
actions: uw::_Unwind_Action,
_uw_exception_class: uw::_Unwind_Exception_Class,
uw_exception: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context,
_stop_parameter: *mut c_void)
-> uw::_Unwind_Reason_Code {
unsafe {
let exception_info = &mut *(uw_exception as *mut ExceptionInfo);
if exception_info.backtrace_size < exception_info.backtrace.len() {
let ip = uw::_Unwind_GetIP(context);
exception_info.backtrace[exception_info.backtrace_size] = ip;
exception_info.backtrace_size += 1;
}
if actions as u32 & uw::_UA_END_OF_STACK as u32 != 0 {
::terminate(&exception_info.exception.unwrap(),
exception_info.backtrace[..exception_info.backtrace_size].as_mut())
} else {
uw::_URC_NO_REASON
}
}
}
// We can unfortunately not use mem::zeroed in a static, so Option<> is used as a workaround.
// See https://github.com/rust-lang/rust/issues/39498.
static mut INFLIGHT: ExceptionInfo = ExceptionInfo {
uw_exception: uw::_Unwind_Exception {
exception_class: EXCEPTION_CLASS,
@ -160,44 +179,40 @@ static mut INFLIGHT: ExceptionInfo = ExceptionInfo {
backtrace_size: 0
};
#[export_name="__artiq_raise"]
#[unwind(allowed)]
pub unsafe extern fn raise(exception: *const Exception) -> ! {
// Zing! The Exception<'a> to Exception<'static> transmute is not really sound in case
// the exception is ever captured. Fortunately, they currently aren't, and we save
// on the hassle of having to allocate exceptions somewhere except on stack.
debug!("Trying to raise exception");
INFLIGHT.exception = Some(mem::transmute::<Exception, Exception<'static>>(*exception));
INFLIGHT.handled = false;
let result = uw::_Unwind_RaiseException(&mut INFLIGHT.uw_exception);
assert!(result == uw::_URC_END_OF_STACK);
debug!("Result: {:?}", result);
INFLIGHT.backtrace_size = 0;
let _result = _Unwind_ForcedUnwind(&mut INFLIGHT.uw_exception,
uncaught_exception, ptr::null_mut());
unreachable!()
unimplemented!("top level exception handling");
}
#[export_name="__artiq_reraise"]
#[unwind(allowed)]
pub unsafe extern fn reraise() -> ! {
use cslice::AsCSlice;
if INFLIGHT.handled {
match INFLIGHT.exception {
Some(ref exception) => raise(exception),
None => raise(&Exception {
name: "0:artiq.coredevice.exceptions.RuntimeError".as_c_slice(),
file: file!().as_c_slice(),
line: line!(),
column: column!(),
// https://github.com/rust-lang/rfcs/pull/1719
function: "__artiq_reraise".as_c_slice(),
message: "No active exception to reraise".as_c_slice(),
param: [0, 0, 0]
})
}
} else {
uw::_Unwind_Resume(&mut INFLIGHT.uw_exception)
debug!("Re-raise");
// current implementation uses raise as _Unwind_Resume is not working now
// would debug that later.
match INFLIGHT.exception {
Some(ref exception) => raise(exception),
None => raise(&Exception {
name: "0:artiq.coredevice.exceptions.RuntimeError".as_c_slice(),
file: file!().as_c_slice(),
line: line!(),
column: column!(),
// https://github.com/rust-lang/rfcs/pull/1719
function: "__artiq_reraise".as_c_slice(),
message: "No active exception to reraise".as_c_slice(),
param: [0, 0, 0]
})
}
}

16
src/runtime/src/kernel.rs

@ -7,6 +7,7 @@ use libcortex_a9::{cache::dcci_slice, mutex::Mutex, sync_channel::{self, sync_ch
use libsupport_zynq::boot::Core1;
use dyld;
use crate::eh_artiq;
use crate::rpc;
use crate::rtio;
@ -132,10 +133,6 @@ extern fn rpc_recv(slot: *mut ()) -> usize {
}
}
extern fn exception_unimplemented() {
unimplemented!();
}
macro_rules! api {
($i:ident) => ({
extern { static $i: u8; }
@ -250,12 +247,13 @@ fn resolve(required: &[u8]) -> Option<u32> {
api!(__aeabi_memclr8),
api!(__aeabi_memclr4),
api!(__aeabi_memclr),
// libc
api!(memcmp, extern { fn memcmp(a: *const u8, b: *mut u8, size: usize); }),
// exceptions
api!(_Unwind_Resume = exception_unimplemented),
api!(__artiq_personality = exception_unimplemented),
api!(__artiq_raise = exception_unimplemented),
api!(__artiq_reraise = exception_unimplemented),
api!(_Unwind_Resume = unwind::_Unwind_Resume),
api!(__artiq_personality = eh_artiq::artiq_personality),
api!(__artiq_raise = eh_artiq::raise),
api!(__artiq_reraise = eh_artiq::reraise),
];
api.iter()

1
src/runtime/src/main.rs

@ -23,6 +23,7 @@ mod rtio;
mod kernel;
mod moninj;
mod load_pl;
mod eh_artiq;
fn identifier_read(buf: &mut [u8]) -> &str {
unsafe {

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