Skip to content

S
swiftshader
Commit 66478362 by Nicolas Capens
Options

Implement support for ELF relocations.

Bug swiftshader:17 Change-Id: I3ba076bdfd733797f627c50c37dea83326ddee35 Reviewed-on: https://swiftshader-review.googlesource.com/7714Reviewed-by: 's avatarNicolas Capens <capn@google.com> Tested-by: 's avatarNicolas Capens <capn@google.com> Reviewed-on: https://swiftshader-review.googlesource.com/7670
parent 13ac2327
Showing with 177 additions and 12 deletions
src/Reactor/SubzeroReactor.cpp
......@@ -98,9 +98,136 @@ namespace sw
Optimization optimization[10] = {InstructionCombining, Disabled};
using ElfHeader = std::conditional<sizeof(void*) == 8, Elf64_Ehdr, Elf32_Ehdr>::type;
using SectionHeader = std::conditional<sizeof(void*) == 8, Elf64_Shdr, Elf32_Shdr>::type;
inline const SectionHeader *sectionHeader(const ElfHeader *elfHeader)
{
return reinterpret_cast<const SectionHeader*>((intptr_t)elfHeader + elfHeader->e_shoff);
}
inline const SectionHeader *elfSection(const ElfHeader *elfHeader, int index)
{
return &sectionHeader(elfHeader)[index];
}
static void *relocateSymbol(const ElfHeader *elfHeader, const Elf32_Rel &relocation, const SectionHeader &relocationTable)
{
const SectionHeader *target = elfSection(elfHeader, relocationTable.sh_info);
intptr_t address = (intptr_t)elfHeader + target->sh_offset;
int32_t *patchSite = (int*)(address + relocation.r_offset);
uint32_t index = relocation.getSymbol();
int table = relocationTable.sh_link;
void *symbolValue = nullptr;
if(index != SHN_UNDEF)
{
if(table == SHN_UNDEF) return nullptr;
const SectionHeader *symbolTable = elfSection(elfHeader, table);
uint32_t symtab_entries = symbolTable->sh_size / symbolTable->sh_entsize;
if(index >= symtab_entries)
{
assert(index < symtab_entries && "Symbol Index out of range");
return nullptr;
}
intptr_t symbolAddress = (intptr_t)elfHeader + symbolTable->sh_offset;
Elf32_Sym &symbol = ((Elf32_Sym*)symbolAddress)[index];
uint16_t section = symbol.st_shndx;
if(section != SHN_UNDEF && section < SHN_LORESERVE)
{
const SectionHeader *target = elfSection(elfHeader, symbol.st_shndx);
symbolValue = reinterpret_cast<void*>((intptr_t)elfHeader + symbol.st_value + target->sh_offset);
}
else
{
return nullptr;
}
}
switch(relocation.getType())
{
case R_386_NONE:
// No relocation
break;
case R_386_32:
*patchSite = (int32_t)((intptr_t)symbolValue + *patchSite);
break;
// case R_386_PC32:
// *patchSite = (int32_t)((intptr_t)symbolValue + *patchSite - (intptr_t)patchSite);
// break;
default:
assert(false && "Unsupported relocation type");
return nullptr;
}
return symbolValue;
}
static void *relocateSymbol(const ElfHeader *elfHeader, const Elf64_Rela &relocation, const SectionHeader &relocationTable)
{
const SectionHeader *target = elfSection(elfHeader, relocationTable.sh_info);
intptr_t address = (intptr_t)elfHeader + target->sh_offset;
int32_t *patchSite = (int*)(address + relocation.r_offset);
uint32_t index = relocation.getSymbol();
int table = relocationTable.sh_link;
void *symbolValue = nullptr;
if(index != SHN_UNDEF)
{
if(table == SHN_UNDEF) return nullptr;
const SectionHeader *symbolTable = elfSection(elfHeader, table);
uint32_t symtab_entries = symbolTable->sh_size / symbolTable->sh_entsize;
if(index >= symtab_entries)
{
assert(index < symtab_entries && "Symbol Index out of range");
return nullptr;
}
intptr_t symbolAddress = (intptr_t)elfHeader + symbolTable->sh_offset;
Elf64_Sym &symbol = ((Elf64_Sym*)symbolAddress)[index];
uint16_t section = symbol.st_shndx;
if(section != SHN_UNDEF && section < SHN_LORESERVE)
{
const SectionHeader *target = elfSection(elfHeader, symbol.st_shndx);
symbolValue = reinterpret_cast<void*>((intptr_t)elfHeader + symbol.st_value + target->sh_offset);
}
else
{
return nullptr;
}
}
switch(relocation.getType())
{
case R_X86_64_NONE:
// No relocation
break;
// case R_X86_64_64:
// *patchSite = (int32_t)((intptr_t)symbolValue + *patchSite) + relocation->r_addend;
// break;
case R_X86_64_PC32:
*patchSite = (int32_t)((intptr_t)symbolValue + *patchSite - (intptr_t)patchSite) + relocation.r_addend;
break;
// case R_X86_64_32S:
// *patchSite = (int32_t)((intptr_t)symbolValue + *patchSite) + relocation.r_addend;
// break;
default:
assert(false && "Unsupported relocation type");
return nullptr;
}
return symbolValue;
}
void *loadImage(uint8_t *const elfImage)
{
using ElfHeader = std::conditional<sizeof(void*) == 8, Elf64_Ehdr, Elf32_Ehdr>::type;
ElfHeader *elfHeader = (ElfHeader*)elfImage;
if(!elfHeader->checkMagic())
......@@ -108,15 +235,40 @@ namespace sw
return nullptr;
}
using SectionHeader = std::conditional<sizeof(void*) == 8, Elf64_Shdr, Elf32_Shdr>::type;
// Expect ELF bitness to match platform
assert(sizeof(void*) == 8 ? elfHeader->e_machine == EM_X86_64 : elfHeader->e_machine == EM_386);
SectionHeader *sectionHeader = (SectionHeader*)(elfImage + elfHeader->e_shoff);
void *entry = nullptr;
for(int i = 0; i < elfHeader->e_shnum; i++)
{
if(sectionHeader[i].sh_type == SHT_PROGBITS && sectionHeader[i].sh_flags & SHF_EXECINSTR)
if(sectionHeader[i].sh_type == SHT_PROGBITS)
{
entry = elfImage + sectionHeader[i].sh_offset;
if(sectionHeader[i].sh_flags & SHF_EXECINSTR)
{
entry = elfImage + sectionHeader[i].sh_offset;
}
}
else if(sectionHeader[i].sh_type == SHT_REL)
{
assert(sizeof(void*) == 4 && "UNIMPLEMENTED"); // Only expected/implemented for 32-bit code
for(int index = 0; index < sectionHeader[i].sh_size / sectionHeader[i].sh_entsize; index++)
{
const Elf32_Rel &relocation = ((const Elf32_Rel*)(elfImage + sectionHeader[i].sh_offset))[index];
void *symbol = relocateSymbol(elfHeader, relocation, sectionHeader[i]);
}
}
else if(sectionHeader[i].sh_type == SHT_RELA)
{
assert(sizeof(void*) == 8 && "UNIMPLEMENTED"); // Only expected/implemented for 64-bit code
for(int index = 0; index < sectionHeader[i].sh_size / sectionHeader[i].sh_entsize; index++)
{
const Elf64_Rela &relocation = ((const Elf64_Rela*)(elfImage + sectionHeader[i].sh_offset))[index];
void *symbol = relocateSymbol(elfHeader, relocation, sectionHeader[i]);
}
}
}
......@@ -193,8 +345,8 @@ namespace sw
const void *getEntry() override
{
VirtualProtect(&buffer[0], buffer.size(), PAGE_EXECUTE_READ, &oldProtection);
position = std::numeric_limits<std::size_t>::max(); // Can't write more data after this
VirtualProtect(&buffer[0], buffer.size(), PAGE_EXECUTE_READWRITE, &oldProtection);
position = std::numeric_limits<std::size_t>::max(); // Can't stream more data after this
return loadImage(&buffer[0]);
}
......@@ -209,10 +361,13 @@ namespace sw
{
::codegenMutex.lock(); // Reactor is currently not thread safe
Ice::ClFlags::Flags.setTargetArch(sizeof(void*) == 8 ? Ice::Target_X8664 : Ice::Target_X8632);
Ice::ClFlags::Flags.setOutFileType(Ice::FT_Elf);
Ice::ClFlags::Flags.setOptLevel(Ice::Opt_2);
Ice::ClFlags::Flags.setApplicationBinaryInterface(Ice::ABI_Platform);
Ice::ClFlags &Flags = Ice::ClFlags::Flags;
Ice::ClFlags::getParsedClFlags(Flags);
Flags.setTargetArch(sizeof(void*) == 8 ? Ice::Target_X8664 : Ice::Target_X8632);
Flags.setOutFileType(Ice::FT_Elf);
Flags.setOptLevel(Ice::Opt_2);
Flags.setApplicationBinaryInterface(Ice::ABI_Platform);
std::unique_ptr<Ice::Ostream> cout(new llvm::raw_os_ostream(std::cout));
......@@ -255,12 +410,22 @@ namespace sw
::function->setFunctionName(Ice::GlobalString::createWithString(::context, asciiName));
::function->translate();
auto *globals = ::function->getGlobalInits().release();
if(globals && !globals->empty())
{
::context->getGlobals()->merge(globals);
}
::context->emitFileHeader();
::function->emitIAS();
auto assembler = ::function->releaseAssembler();
::context->getObjectWriter()->writeFunctionCode(::function->getFunctionName(), false, assembler.get());
::context->getObjectWriter()->writeNonUserSections();
auto objectWriter = ::context->getObjectWriter();
assembler->alignFunction();
objectWriter->writeFunctionCode(::function->getFunctionName(), false, assembler.get());
::context->lowerGlobals("last");
objectWriter->setUndefinedSyms(::context->getConstantExternSyms());
objectWriter->writeNonUserSections();
return ::routine;
}
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment