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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
90 lines
3.1 KiB
YAML
90 lines
3.1 KiB
YAML
# RUN: yaml2obj %s -o %t.obj
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# RUN: env LLD_IN_TEST=1 not lld-link /out:%t.exe /entry:func1 /subsystem:console %t.obj 2>&1 | FileCheck %s
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# This file is like pdata-arm64.yaml, except that .pdata has been extended with
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# 4 bytes. This can happen due to for example bad assembler input. Check that
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# lld errors gracefully instead of crashing.
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# CHECK: unexpected .pdata size: 20 is not a multiple of 8
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--- !COFF
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header:
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Machine: IMAGE_FILE_MACHINE_ARM64
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Characteristics: [ ]
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sections:
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- Name: .text
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Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
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Alignment: 4
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SectionData: ff4300d1f37b00a9f303012a00000094e003132a00000094f37b40a9ff430091c0035fd6f353bea9fe0b00f9f303012af403022a00000094e003132a00000094e003142a00000094fe0b40f9f353c2a8c0035fd6c0035fd6
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Relocations:
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- VirtualAddress: 12
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SymbolName: func3
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Type: IMAGE_REL_ARM64_BRANCH26
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- VirtualAddress: 20
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SymbolName: func3
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Type: IMAGE_REL_ARM64_BRANCH26
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- VirtualAddress: 52
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SymbolName: func3
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Type: IMAGE_REL_ARM64_BRANCH26
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- VirtualAddress: 60
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SymbolName: func3
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Type: IMAGE_REL_ARM64_BRANCH26
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- VirtualAddress: 68
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SymbolName: func3
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Type: IMAGE_REL_ARM64_BRANCH26
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- Name: .pdata
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Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
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Alignment: 4
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SectionData: 0000000031002201000000002500a10000000000
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Relocations:
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- VirtualAddress: 0
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SymbolName: func2
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Type: IMAGE_REL_ARM64_ADDR32NB
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- VirtualAddress: 8
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SymbolName: func1
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Type: IMAGE_REL_ARM64_ADDR32NB
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symbols:
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- Name: .text
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Value: 0
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_NULL
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StorageClass: IMAGE_SYM_CLASS_STATIC
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SectionDefinition:
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Length: 57
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NumberOfRelocations: 0
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NumberOfLinenumbers: 0
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CheckSum: 0
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Number: 1
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- Name: .pdata
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Value: 0
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SectionNumber: 2
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_NULL
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StorageClass: IMAGE_SYM_CLASS_STATIC
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SectionDefinition:
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Length: 20
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NumberOfRelocations: 2
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NumberOfLinenumbers: 0
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CheckSum: 0
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Number: 2
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- Name: func1
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Value: 0
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_FUNCTION
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StorageClass: IMAGE_SYM_CLASS_EXTERNAL
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- Name: func2
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Value: 36
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_FUNCTION
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StorageClass: IMAGE_SYM_CLASS_EXTERNAL
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- Name: func3
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Value: 84
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_NULL
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StorageClass: IMAGE_SYM_CLASS_EXTERNAL
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...
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