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[BOLT] Fix relocations handling (#100890)

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After porting BOLT to RISCV some of the relocations were broken on both
AArch64 and X86.
On AArch64 the example of broken relocations would be GOT, during
handling them, we should replace the symbol to __BOLT_got_zero in order
to address GOT entry, not the symbol that addresses this entry. This is
done further in code, so it is too early to add rel here.
On X86 it is a mistake to add relocations without addend. This is the
exact problem that is raised on #97937. Due to different code generation
I had to use gcc-generated yaml test, since with clang I wasn't able to
reproduce problem.
Added tests for both architectures and made the problematic condition
riscV-specific.
This commit is contained in:
Vladislav Khmelevsky
2024-08-07 16:25:46 +04:00
committed by GitHub
parent 25acc16fe2
commit 097ddd3565
5 changed files with 369 additions and 1 deletions
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2
bolt/lib/Rewrite/RewriteInstance.cpp
View File

@@ -2612,7 +2612,7 @@ void RewriteInstance::handleRelocation(const SectionRef &RelocatedSection,
Expected<StringRef> SectionName = Section->getName();
if (SectionName && !SectionName->empty())
ReferencedSection = BC->getUniqueSectionByName(*SectionName);
} else if (ReferencedSymbol && ContainingBF &&
} else if (BC->isRISCV() && ReferencedSymbol && ContainingBF &&
(cantFail(Symbol.getFlags()) & SymbolRef::SF_Absolute)) {
// This might be a relocation for an ABS symbols like __global_pointer$ on
// RISC-V

9
bolt/test/AArch64/Inputs/build_id.ldscript Normal file
View File

@@ -0,0 +1,9 @@
SECTIONS
{
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000)); . = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS;
.note.gnu.build-id (0x400400):
{
build_id_note = ABSOLUTE(.);
*(.note.gnu.build-id)
}
}

25
bolt/test/AArch64/build_id.c Normal file
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@@ -0,0 +1,25 @@
// This test checks that referencing build_id through GOT table
// would result in GOT access after disassembly, not directly
// to build_id address.
// RUN: %clang %cflags -fuse-ld=lld -Wl,-T,%S/Inputs/build_id.ldscript -Wl,-q \
// RUN: -Wl,--no-relax -Wl,--build-id=sha1 %s -o %t.exe
// RUN: llvm-bolt -print-disasm --print-only=get_build_id %t.exe -o %t.bolt | \
// RUN: FileCheck %s
// CHECK: adrp [[REG:x[0-28]+]], __BOLT_got_zero
// CHECK: ldr x{{.*}}, [[[REG]], :lo12:__BOLT_got_zero{{.*}}]
struct build_id_note {
char pad[16];
char hash[20];
};
extern const struct build_id_note build_id_note;
__attribute__((noinline)) char get_build_id() { return build_id_note.hash[0]; }
int main() {
get_build_id();
return 0;
}

326
bolt/test/X86/Inputs/build_id.yaml Normal file
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@@ -0,0 +1,326 @@
--- !ELF
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Flags: [ PF_R ]
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Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x400400
AddressAlign: 0x4
Offset: 0x400
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Desc: 3C34F7D1612996940C48F98DC272543BC3C9C956
Type: NT_PRPSINFO
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Notes:
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Desc: '00000000030000000200000000000000'
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Type: SHT_PROGBITS
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Type: SHT_GNU_HASH
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Link: .dynsym
AddressAlign: 0x8
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Type: SHT_FINI_ARRAY
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Link: .dynstr
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Value: 0x404000
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Value: 0x30
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Value: 0x7
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Value: 0x8
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Value: 0x8000001
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Value: 0x400608
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Value: 0x1
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Value: 0x4005F2
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Value: 0x3
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Value: 0x0
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x404028
AddressAlign: 0x8
Content: '00000000000000003040400000000000'
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Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
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Type: SHT_RELA
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Relocations:
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Symbol: print_build_id
Type: R_X86_64_PLT32
Addend: -4
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Addend: 12
- Type: SectionHeaderTable
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- Name: .init_array
- Name: .fini_array
- Name: .dynamic
- Name: .data
- Name: .tm_clone_table
- Name: .bss
- Name: .symtab
- Name: .strtab
- Name: .shstrtab
Symbols:
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Type: STT_FUNC
Section: .text
Binding: STB_GLOBAL
Value: 0x401190
Size: 0x49
- Name: _end
Section: .bss
Binding: STB_GLOBAL
Value: 0x404040
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Type: STT_FUNC
Section: .text
Binding: STB_GLOBAL
Value: 0x4010A0
Size: 0x26
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Section: .bss
Binding: STB_GLOBAL
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Type: STT_FUNC
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Size: 0x16
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Index: SHN_ABS
Binding: STB_GLOBAL
Value: 0x400400
...

8
bolt/test/X86/build_id.test Normal file
View File

@@ -0,0 +1,8 @@
// This test checks that relocation addend used to address build_id fields
// is properly disassembled by BOLT.
RUN: yaml2obj %p/Inputs/build_id.yaml &> %t.exe
RUN: llvm-bolt -print-disasm --print-only=print_build_id %t.exe -o %t.bolt | \
RUN: FileCheck %s
CHECK: leaq build_id_note+16(%rip), %rbx