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Use DataExtractor to decode SLEB128 in android_relas.

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A simple refactoring patch which let us use `DataExtractor::getSLEB128` rather than using a lambda function.

Differential Revision: https://reviews.llvm.org/D95158
This commit is contained in:
Rahman Lavaee 2021-01-22 09:13:30 -08:00
parent 9096396021
commit a688c9d8f1
2 changed files with 24 additions and 36 deletions
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58
lib/Object/ELF.cpp
View File

@ -8,7 +8,7 @@
#include "llvm/Object/ELF.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/DataExtractor.h"
using namespace llvm;
using namespace object;
@ -373,39 +373,31 @@ ELFFile<ELFT>::android_relas(const Elf_Shdr &Sec) const {
Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
if (!ContentsOrErr)
return ContentsOrErr.takeError();
const uint8_t *Cur = ContentsOrErr->begin();
const uint8_t *End = ContentsOrErr->end();
if (ContentsOrErr->size() < 4 || Cur[0] != 'A' || Cur[1] != 'P' ||
Cur[2] != 'S' || Cur[3] != '2')
ArrayRef<uint8_t> Content = *ContentsOrErr;
if (Content.size() < 4 || Content[0] != 'A' || Content[1] != 'P' ||
Content[2] != 'S' || Content[3] != '2')
return createError("invalid packed relocation header");
Cur += 4;
DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4);
DataExtractor::Cursor Cur(/*Offset=*/4);
const char *ErrStr = nullptr;
auto ReadSLEB = [&]() -> int64_t {
if (ErrStr)
return 0;
unsigned Len;
int64_t Result = decodeSLEB128(Cur, &Len, End, &ErrStr);
Cur += Len;
return Result;
};
uint64_t NumRelocs = ReadSLEB();
uint64_t Offset = ReadSLEB();
uint64_t NumRelocs = Data.getSLEB128(Cur);
uint64_t Offset = Data.getSLEB128(Cur);
uint64_t Addend = 0;
if (ErrStr)
return createError(ErrStr);
if (!Cur)
return std::move(Cur.takeError());
std::vector<Elf_Rela> Relocs;
Relocs.reserve(NumRelocs);
while (NumRelocs) {
uint64_t NumRelocsInGroup = ReadSLEB();
uint64_t NumRelocsInGroup = Data.getSLEB128(Cur);
if (!Cur)
return std::move(Cur.takeError());
if (NumRelocsInGroup > NumRelocs)
return createError("relocation group unexpectedly large");
NumRelocs -= NumRelocsInGroup;
uint64_t GroupFlags = ReadSLEB();
uint64_t GroupFlags = Data.getSLEB128(Cur);
bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG;
bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG;
bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG;
@ -413,34 +405,30 @@ ELFFile<ELFT>::android_relas(const Elf_Shdr &Sec) const {
uint64_t GroupOffsetDelta;
if (GroupedByOffsetDelta)
GroupOffsetDelta = ReadSLEB();
GroupOffsetDelta = Data.getSLEB128(Cur);
uint64_t GroupRInfo;
if (GroupedByInfo)
GroupRInfo = ReadSLEB();
GroupRInfo = Data.getSLEB128(Cur);
if (GroupedByAddend && GroupHasAddend)
Addend += ReadSLEB();
Addend += Data.getSLEB128(Cur);
if (!GroupHasAddend)
Addend = 0;
for (uint64_t I = 0; I != NumRelocsInGroup; ++I) {
for (uint64_t I = 0; Cur && I != NumRelocsInGroup; ++I) {
Elf_Rela R;
Offset += GroupedByOffsetDelta ? GroupOffsetDelta : ReadSLEB();
Offset += GroupedByOffsetDelta ? GroupOffsetDelta : Data.getSLEB128(Cur);
R.r_offset = Offset;
R.r_info = GroupedByInfo ? GroupRInfo : ReadSLEB();
R.r_info = GroupedByInfo ? GroupRInfo : Data.getSLEB128(Cur);
if (GroupHasAddend && !GroupedByAddend)
Addend += ReadSLEB();
Addend += Data.getSLEB128(Cur);
R.r_addend = Addend;
Relocs.push_back(R);
if (ErrStr)
return createError(ErrStr);
}
if (ErrStr)
return createError(ErrStr);
if (!Cur)
return std::move(Cur.takeError());
}
return Relocs;

2
test/tools/llvm-readobj/ELF/packed-relocs-errors.s
View File

@ -23,7 +23,7 @@
.section .rela.dyn, "a", @0x60000001
.ascii "APS2"
# ERR-PAST-END: warning: '[[FILE]]': unable to read relocations from SHT_ANDROID_REL section with index 3: malformed sleb128, extends past end
# ERR-PAST-END: warning: '[[FILE]]': unable to read relocations from SHT_ANDROID_REL section with index 3: unable to decode LEB128 at offset 0x{{([[:xdigit:]]{8})}}: malformed sleb128, extends past end
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %t/asm3.s -o %t3.o
# RUN: llvm-readobj --relocations %t3.o 2>&1 | FileCheck %s -DFILE=%t3.o --check-prefix=ERR-PAST-END