2017-12-14 16:56:36 +08:00
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// REQUIRES: arm
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// RUN: llvm-mc -filetype=obj -triple=thumbv7a-windows-gnu %s -o %t.obj
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[LLD][COFF] When using LLD-as-a-library, always prevent re-entrance on failures
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
2020-11-12 21:14:20 +08:00
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// RUN: env LLD_IN_TEST=1 not lld-link -entry:_start -subsystem:console %t.obj -out:%t.exe 2>&1 | FileCheck %s
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2017-12-14 16:56:36 +08:00
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.syntax unified
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.globl _start
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_start:
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bne too_far20
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2018-09-25 18:59:29 +08:00
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.space 0x100000
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.section .text$a, "xr"
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too_far20:
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bx lr
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2017-12-14 16:56:36 +08:00
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2018-09-25 18:59:29 +08:00
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// When trying to add a thunk at the end of the section, the thunk itself
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// will be too far away, so this won't converge.
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// CHECK: adding thunks hasn't converged
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