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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:🧝: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
113 lines
3.4 KiB
C++
113 lines
3.4 KiB
C++
//===-- Process.cpp - Implement OS Process Concept --------------*- C++ -*-===//
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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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//
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// This file implements the operating system Process concept.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/Process.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Config/config.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/Support/CrashRecoveryContext.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/Program.h"
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#include <stddef.h> // for _Exit
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using namespace llvm;
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using namespace sys;
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//===----------------------------------------------------------------------===//
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//=== WARNING: Implementation here must contain only TRULY operating system
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//=== independent code.
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//===----------------------------------------------------------------------===//
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Optional<std::string>
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Process::FindInEnvPath(StringRef EnvName, StringRef FileName, char Separator) {
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return FindInEnvPath(EnvName, FileName, {}, Separator);
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}
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Optional<std::string> Process::FindInEnvPath(StringRef EnvName,
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StringRef FileName,
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ArrayRef<std::string> IgnoreList,
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char Separator) {
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assert(!path::is_absolute(FileName));
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Optional<std::string> FoundPath;
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Optional<std::string> OptPath = Process::GetEnv(EnvName);
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if (!OptPath.hasValue())
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return FoundPath;
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const char EnvPathSeparatorStr[] = {Separator, '\0'};
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SmallVector<StringRef, 8> Dirs;
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SplitString(OptPath.getValue(), Dirs, EnvPathSeparatorStr);
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for (StringRef Dir : Dirs) {
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if (Dir.empty())
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continue;
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if (any_of(IgnoreList, [&](StringRef S) { return fs::equivalent(S, Dir); }))
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continue;
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SmallString<128> FilePath(Dir);
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path::append(FilePath, FileName);
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if (fs::exists(Twine(FilePath))) {
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FoundPath = std::string(FilePath.str());
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break;
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}
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}
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return FoundPath;
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}
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#define COLOR(FGBG, CODE, BOLD) "\033[0;" BOLD FGBG CODE "m"
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#define ALLCOLORS(FGBG,BOLD) {\
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COLOR(FGBG, "0", BOLD),\
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COLOR(FGBG, "1", BOLD),\
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COLOR(FGBG, "2", BOLD),\
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COLOR(FGBG, "3", BOLD),\
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COLOR(FGBG, "4", BOLD),\
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COLOR(FGBG, "5", BOLD),\
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COLOR(FGBG, "6", BOLD),\
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COLOR(FGBG, "7", BOLD)\
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}
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static const char colorcodes[2][2][8][10] = {
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{ ALLCOLORS("3",""), ALLCOLORS("3","1;") },
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{ ALLCOLORS("4",""), ALLCOLORS("4","1;") }
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};
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// A CMake option controls wheter we emit core dumps by default. An application
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// may disable core dumps by calling Process::PreventCoreFiles().
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static bool coreFilesPrevented = !LLVM_ENABLE_CRASH_DUMPS;
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bool Process::AreCoreFilesPrevented() { return coreFilesPrevented; }
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LLVM_ATTRIBUTE_NORETURN
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void Process::Exit(int RetCode, bool NoCleanup) {
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if (CrashRecoveryContext *CRC = CrashRecoveryContext::GetCurrent())
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CRC->HandleExit(RetCode);
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if (NoCleanup)
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_Exit(RetCode);
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else
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::exit(RetCode);
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}
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// Include the platform-specific parts of this class.
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#ifdef LLVM_ON_UNIX
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#include "Unix/Process.inc"
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#endif
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#ifdef _WIN32
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#include "Windows/Process.inc"
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#endif
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