From eb750eb1f0051a58d0cf6f7bce78b47227ca3a9d Mon Sep 17 00:00:00 2001 From: pca006132 Date: Thu, 2 Jul 2020 10:10:33 +0800 Subject: [PATCH] Exception handling: patched exception handling for ARTIQ. --- src/armv7-none-eabihf.json | 2 + src/runtime/src/eh_artiq.rs | 245 +++++++++++++++++++----------------- src/runtime/src/kernel.rs | 16 ++- src/runtime/src/main.rs | 1 + 4 files changed, 140 insertions(+), 124 deletions(-) diff --git a/src/armv7-none-eabihf.json b/src/armv7-none-eabihf.json index 4fc452f6..a677f3a4 100644 --- a/src/armv7-none-eabihf.json +++ b/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", diff --git a/src/runtime/src/eh_artiq.rs b/src/runtime/src/eh_artiq.rs index 8bfc171a..a81dd3d7 100644 --- a/src/runtime/src/eh_artiq.rs +++ b/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 @@ // , 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 libc::{c_int, uintptr_t}; +use log::debug; -use eh::dwarf::{self, EHAction}; +use dwarf::eh::{self, EHAction, EHContext}; -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; -} + +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 +unsafe fn find_eh_action( + context: *mut uw::_Unwind_Context, + foreign_exception: bool, +) -> Result { + 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) +} -#[cfg(any(target_arch = "or1k"))] -const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 - -#[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); } + 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; + }; - let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8; - let ip = uw::_Unwind_GetIP(context) - 1; - let func_start = uw::_Unwind_GetRegionStart(context); + // 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_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, + 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; } + 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 { - 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, - } + 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)); 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] + }) } } + diff --git a/src/runtime/src/kernel.rs b/src/runtime/src/kernel.rs index a590b1e5..5e8df096 100644 --- a/src/runtime/src/kernel.rs +++ b/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 { 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() diff --git a/src/runtime/src/main.rs b/src/runtime/src/main.rs index 4734b472..21402a9e 100644 --- a/src/runtime/src/main.rs +++ b/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 {