45b8a741fb
This is a follow-up for D70378 (Cover usage of LLD as a library). While debugging an intermittent failure on a bot, I recalled this scenario which causes the issue: 1.When executing lld/test/ELF/invalid/symtab-sh-info.s L45, we reach lld::elf::Obj-File::ObjFile() which goes straight into its base ELFFileBase(), then ELFFileBase::init(). 2.At that point fatal() is thrown in lld/ELF/InputFiles.cpp L381, leaving a half-initialized ObjFile instance. 3.We then end up in lld::exitLld() and since we are running with LLD_IN_TEST, we hapily restore the control flow to CrashRecoveryContext::RunSafely() then back in lld::safeLldMain(). 4.Before this patch, we called errorHandler().reset() just after, and this attempted to reset the associated SpecificAlloc<ObjFile<ELF64LE>>. That tried to free the half-initialized ObjFile instance, and more precisely its ObjFile::dwarf member. Sometimes that worked, sometimes it failed and was catched by the CrashRecoveryContext. This scenario was the reason we called errorHandler().reset() through a CrashRecoveryContext. But in some rare cases, the above repro somehow corrupted the heap, creating a stack overflow. When the CrashRecoveryContext's filter (that is, __except (ExceptionFilter(GetExceptionInformation()))) tried to handle the exception, it crashed again since the stack was exhausted -- and that took the whole application down. That is the issue seen on the bot. Locally it happens about 1 times out of 15. Now this situation can happen anywhere in LLD. Since catching stack overflows is not a reliable scenario ATM when using CrashRecoveryContext, we're now preventing further re-entrance when such failures occur, by signaling lld::SafeReturn::canRunAgain=false. When running with LLD_IN_TEST=2 (or above), only one iteration will be executed, instead of two. Differential Revision: https://reviews.llvm.org/D88348
62 lines
2.0 KiB
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62 lines
2.0 KiB
C++
//===- lld/Common/Driver.h - Linker Driver Emulator -----------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_COMMON_DRIVER_H
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#define LLD_COMMON_DRIVER_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/Support/raw_ostream.h"
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namespace lld {
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struct SafeReturn {
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int ret;
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bool canRunAgain;
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};
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// Generic entry point when using LLD as a library, safe for re-entry, supports
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// crash recovery. Returns a general completion code and a boolean telling
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// whether it can be called again. In some cases, a crash could corrupt memory
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// and re-entry would not be possible anymore. Use exitLld() in that case to
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// properly exit your application and avoid intermittent crashes on exit caused
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// by cleanup.
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SafeReturn safeLldMain(int argc, const char **argv, llvm::raw_ostream &stdoutOS,
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llvm::raw_ostream &stderrOS);
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namespace coff {
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bool link(llvm::ArrayRef<const char *> args, bool canExitEarly,
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llvm::raw_ostream &stdoutOS, llvm::raw_ostream &stderrOS);
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}
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namespace mingw {
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bool link(llvm::ArrayRef<const char *> args, bool canExitEarly,
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llvm::raw_ostream &stdoutOS, llvm::raw_ostream &stderrOS);
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}
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namespace elf {
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bool link(llvm::ArrayRef<const char *> args, bool canExitEarly,
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llvm::raw_ostream &stdoutOS, llvm::raw_ostream &stderrOS);
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}
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namespace mach_o {
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bool link(llvm::ArrayRef<const char *> args, bool canExitEarly,
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llvm::raw_ostream &stdoutOS, llvm::raw_ostream &stderrOS);
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}
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namespace macho {
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bool link(llvm::ArrayRef<const char *> args, bool canExitEarly,
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llvm::raw_ostream &stdoutOS, llvm::raw_ostream &stderrOS);
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}
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namespace wasm {
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bool link(llvm::ArrayRef<const char *> args, bool canExitEarly,
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llvm::raw_ostream &stdoutOS, llvm::raw_ostream &stderrOS);
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}
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}
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#endif
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