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OptimizerBranches.cpp
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OptimizerBranches.cpp
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/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
*
* Copyright (c) 2015 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <unistd.h>
#include <CommonCrypto/CommonDigest.h>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include "StringUtils.h"
#include "Trie.hpp"
#include "MachOFileAbstraction.hpp"
#include "MachOAnalyzer.h"
#include "Diagnostics.h"
#include "DyldSharedCache.h"
#include "CacheBuilder.h"
static const bool verbose = false;
template <typename P>
class StubOptimizer {
public:
void redirectCallSitesToIslands();
StubOptimizer(int64_t cacheSlide,
const std::string& archName,
const CacheBuilder::StubOptimizerInfo& image,
const std::unordered_map<uint64_t, std::pair<uint64_t, uint8_t*>>& stubsToIslands,
Diagnostics& diags);
void buildStubMap(const std::unordered_set<std::string>& neverStubEliminate);
void optimizeStubs();
void optimizeCallSites(std::unordered_map<uint64_t, uint64_t>& targetAddrToOptStubAddr);
const char* dylibID() { return _dylibID; }
const uint8_t* exportsTrie() {
if ( _dyldInfo != nullptr )
return &_linkeditBias[_dyldInfo->export_off()];
else
return &_linkeditBias[_exportTrie->dataoff()];
}
uint32_t exportsTrieSize() {
if ( _dyldInfo != nullptr )
return _dyldInfo->export_size();
else
return _exportTrie->datasize();
}
uint32_t _stubCount = 0;
uint32_t _stubOptimizedCount = 0;
uint32_t _stubsLeftInterposable = 0;
uint32_t _branchToStubCount = 0;
uint32_t _branchOptimizedToDirectCount = 0;
uint32_t _branchToOptimizedStubCount = 0;
uint32_t _branchToReUsedOptimizedStubCount = 0;
private:
typedef std::function<bool(uint8_t callSiteKind, uint64_t callSiteAddr, uint64_t stubAddr, uint32_t& instruction)> CallSiteHandler;
typedef typename P::uint_t pint_t;
typedef typename P::E E;
void forEachCallSiteToAStub(CallSiteHandler);
void optimizeArm64CallSites(std::unordered_map<uint64_t, uint64_t>& targetAddrToOptStubAddr);
void optimizeArm64Stubs();
void redirectArm64CallSitesToIslands();
#if SUPPORT_ARCH_arm64e
void optimizeArm64eStubs();
void redirectArm64eCallSitesToIslands();
#endif
#if SUPPORT_ARCH_arm64_32
void optimizeArm64_32Stubs();
void redirectArm64_32CallSitesToIslands();
#endif
void optimizeArmCallSites(std::unordered_map<uint64_t, uint64_t>& targetAddrToOptStubAddr);
void optimizeArmStubs();
uint64_t lazyPointerAddrFromArm64Stub(const uint8_t* stubInstructions, uint64_t stubVMAddr);
#if SUPPORT_ARCH_arm64e
uint64_t lazyPointerAddrFromArm64eStub(const uint8_t* stubInstructions, uint64_t stubVMAddr);
#endif
#if SUPPORT_ARCH_arm64_32
uint64_t lazyPointerAddrFromArm64_32Stub(const uint8_t* stubInstructions, uint64_t stubVMAddr);
#endif
uint32_t lazyPointerAddrFromArmStub(const uint8_t* stubInstructions, uint32_t stubVMAddr);
int32_t getDisplacementFromThumbBranch(uint32_t instruction, uint32_t instrAddr);
uint32_t setDisplacementInThumbBranch(uint32_t instruction, uint32_t instrAddr,
int32_t displacement, bool targetIsThumb);
uint32_t cpuSubtype() { return ((dyld3::MachOFile*)_mh)->maskedCpuSubtype(); }
struct AddressAndName { pint_t targetVMAddr; const char* targetName; };
typedef std::unordered_map<pint_t, AddressAndName> StubVMAddrToTarget;
typedef const std::unordered_map<uint64_t, std::pair<uint64_t, uint8_t*>> StubsToIslands;
static const int64_t b128MegLimit = 0x07FFFFFF;
static const int64_t b16MegLimit = 0x00FFFFFF;
typedef CacheBuilder::DylibSectionCoalescer::OptimizedSection GOTSection;
Diagnostics& _diagnostics;
macho_header<P>* _mh;
const GOTSection* _coalescedGOTs = nullptr;
const GOTSection* _coalescedAuthGOTs = nullptr;
int64_t _cacheSlide = 0;
uint32_t _linkeditSize = 0;
uint64_t _linkeditAddr = 0;
const uint8_t* _linkeditBias = nullptr;
const char* _dylibID = nullptr;
const macho_symtab_command<P>* _symTabCmd = nullptr;
const macho_dysymtab_command<P>* _dynSymTabCmd = nullptr;
const macho_dyld_info_command<P>* _dyldInfo = nullptr;
const macho_linkedit_data_command<P>* _exportTrie = nullptr;
macho_linkedit_data_command<P>* _splitSegInfoCmd = nullptr;
const macho_section<P>* _textSection = nullptr;
const macho_section<P>* _stubSection = nullptr;
uint32_t _textSectionIndex = 0;
uint32_t _stubSectionIndex = 0;
pint_t _textSegStartAddr = 0;
std::vector<macho_segment_command<P>*> _segCmds;
std::unordered_map<pint_t, pint_t> _stubAddrToLPAddr;
std::unordered_map<pint_t, pint_t> _lpAddrToTargetAddr;
std::unordered_map<pint_t, const char*> _targetAddrToName;
std::unordered_set<uint64_t> _stubsToOptimize;
StubsToIslands& _stubsToIslands;
};
template <typename P>
StubOptimizer<P>::StubOptimizer(int64_t cacheSlide,
const std::string& archName,
const CacheBuilder::StubOptimizerInfo& image,
StubsToIslands& stubsToIslands,
Diagnostics& diags)
: _diagnostics(diags), _mh((macho_header<P>*)image.mh), _coalescedGOTs(image.gots), _coalescedAuthGOTs(image.auth_gots),
_cacheSlide(cacheSlide), _dylibID(image.dylibID), _stubsToIslands(stubsToIslands)
{
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)_mh + sizeof(macho_header<P>));
const uint32_t cmd_count = _mh->ncmds();
macho_segment_command<P>* segCmd;
uint32_t sectionIndex = 0;
const macho_load_command<P>* cmd = cmds;
for (uint32_t i = 0; i < cmd_count; ++i) {
switch (cmd->cmd()) {
case LC_SYMTAB:
_symTabCmd = (macho_symtab_command<P>*)cmd;
break;
case LC_DYSYMTAB:
_dynSymTabCmd = (macho_dysymtab_command<P>*)cmd;
break;
case LC_SEGMENT_SPLIT_INFO:
_splitSegInfoCmd = (macho_linkedit_data_command<P>*)cmd;
break;
case LC_DYLD_INFO:
case LC_DYLD_INFO_ONLY:
_dyldInfo = (macho_dyld_info_command<P>*)cmd;
break;
case LC_DYLD_EXPORTS_TRIE:
_exportTrie = (macho_linkedit_data_command<P>*)cmd;
break;
case macho_segment_command<P>::CMD:
segCmd =( macho_segment_command<P>*)cmd;
_segCmds.push_back(segCmd);
if ( strcmp(segCmd->segname(), "__LINKEDIT") == 0 ) {
_linkeditBias = (uint8_t*)(segCmd->vmaddr() + _cacheSlide - segCmd->fileoff());
_linkeditSize = (uint32_t)segCmd->vmsize();
_linkeditAddr = segCmd->vmaddr();
}
else if ( strcmp(segCmd->segname(), "__TEXT") == 0 ) {
_textSegStartAddr = (pint_t)segCmd->vmaddr();
const macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)segCmd + sizeof(macho_segment_command<P>));
const macho_section<P>* const sectionsEnd = §ionsStart[segCmd->nsects()];
for (const macho_section<P>* sect = sectionsStart; sect < sectionsEnd; ++sect) {
++sectionIndex;
if ( strcmp(sect->sectname(), "__text") == 0 ) {
_textSection = sect;
_textSectionIndex = sectionIndex;
}
else if ( ((sect->flags() & SECTION_TYPE) == S_SYMBOL_STUBS) && (sect->size() != 0) ) {
_stubSection = sect;
_stubSectionIndex = sectionIndex;
}
}
}
break;
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
}
template <typename P>
uint32_t StubOptimizer<P>::lazyPointerAddrFromArmStub(const uint8_t* stubInstructions, uint32_t stubVMAddr)
{
uint32_t stubInstr1 = E::get32(*(uint32_t*)stubInstructions);
uint32_t stubInstr2 = E::get32(*(uint32_t*)(stubInstructions+4));
uint32_t stubInstr3 = E::get32(*(uint32_t*)(stubInstructions+8));
int32_t stubData = E::get32(*(uint32_t*)(stubInstructions+12));
if ( stubInstr1 != 0xe59fc004 ) {
_diagnostics.warning("first instruction of stub (0x%08X) is not 'ldr ip, pc + 12' for stub at addr 0x%0llX in %s",
stubInstr1, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
if ( stubInstr2 != 0xe08fc00c ) {
_diagnostics.warning("second instruction of stub (0x%08X) is not 'add ip, pc, ip' for stub at addr 0x%0llX in %s",
stubInstr1, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
if ( stubInstr3 != 0xe59cf000 ) {
_diagnostics.warning("third instruction of stub (0x%08X) is not 'ldr pc, [ip]' for stub at addr 0x%0llX in %s",
stubInstr1, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
return stubVMAddr + 12 + stubData;
}
template <typename P>
uint64_t StubOptimizer<P>::lazyPointerAddrFromArm64Stub(const uint8_t* stubInstructions, uint64_t stubVMAddr)
{
uint32_t stubInstr1 = E::get32(*(uint32_t*)stubInstructions);
if ( (stubInstr1 & 0x9F00001F) != 0x90000010 ) {
_diagnostics.warning("first instruction of stub (0x%08X) is not ADRP for stub at addr 0x%0llX in %s",
stubInstr1, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
int32_t adrpValue = ((stubInstr1 & 0x00FFFFE0) >> 3) | ((stubInstr1 & 0x60000000) >> 29);
if ( stubInstr1 & 0x00800000 )
adrpValue |= 0xFFF00000;
uint32_t stubInstr2 = E::get32(*(uint32_t*)(stubInstructions + 4));
if ( (stubInstr2 & 0xFFC003FF) != 0xF9400210 ) {
_diagnostics.warning("second instruction of stub (0x%08X) is not LDR for stub at addr 0x%0llX in %s",
stubInstr2, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
uint32_t ldrValue = ((stubInstr2 >> 10) & 0x00000FFF);
return (stubVMAddr & (-4096)) + adrpValue*4096 + ldrValue*8;
}
#if SUPPORT_ARCH_arm64_32
template <typename P>
uint64_t StubOptimizer<P>::lazyPointerAddrFromArm64_32Stub(const uint8_t* stubInstructions, uint64_t stubVMAddr)
{
uint32_t stubInstr1 = E::get32(*(uint32_t*)stubInstructions);
if ( (stubInstr1 & 0x9F00001F) != 0x90000010 ) {
_diagnostics.warning("first instruction of stub (0x%08X) is not ADRP for stub at addr 0x%0llX in %s",
stubInstr1, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
int32_t adrpValue = ((stubInstr1 & 0x00FFFFE0) >> 3) | ((stubInstr1 & 0x60000000) >> 29);
if ( stubInstr1 & 0x00800000 )
adrpValue |= 0xFFF00000;
uint32_t stubInstr2 = E::get32(*(uint32_t*)(stubInstructions + 4));
if ( (stubInstr2 & 0xFFC003FF) != 0xB9400210 ) {
_diagnostics.warning("second instruction of stub (0x%08X) is not LDR for stub at addr 0x%0llX in %s",
stubInstr2, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
uint32_t ldrValue = ((stubInstr2 >> 10) & 0x00000FFF);
return (stubVMAddr & (-4096)) + adrpValue*4096 + ldrValue*4; // LDR Wn has a scale factor of 4
}
#endif
#if SUPPORT_ARCH_arm64e
template <typename P>
uint64_t StubOptimizer<P>::lazyPointerAddrFromArm64eStub(const uint8_t* stubInstructions, uint64_t stubVMAddr)
{
uint32_t stubInstr1 = E::get32(*(uint32_t*)stubInstructions);
// ADRP X17, dyld_ImageLoaderCache@page
if ( (stubInstr1 & 0x9F00001F) != 0x90000011 ) {
_diagnostics.warning("first instruction of stub (0x%08X) is not ADRP for stub at addr 0x%0llX in %s",
stubInstr1, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
int32_t adrpValue = ((stubInstr1 & 0x00FFFFE0) >> 3) | ((stubInstr1 & 0x60000000) >> 29);
if ( stubInstr1 & 0x00800000 )
adrpValue |= 0xFFF00000;
// ADD X17, X17, dyld_ImageLoaderCache@pageoff
uint32_t stubInstr2 = E::get32(*(uint32_t*)(stubInstructions + 4));
if ( (stubInstr2 & 0xFFC003FF) != 0x91000231 ) {
_diagnostics.warning("second instruction of stub (0x%08X) is not ADD for stub at addr 0x%0llX in %s",
stubInstr2, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
uint32_t addValue = ((stubInstr2 & 0x003FFC00) >> 10);
// LDR X16, [X17]
uint32_t stubInstr3 = E::get32(*(uint32_t*)(stubInstructions + 8));
if ( stubInstr3 != 0xF9400230 ) {
_diagnostics.warning("second instruction of stub (0x%08X) is not LDR for stub at addr 0x%0llX in %s",
stubInstr2, (uint64_t)stubVMAddr, _dylibID);
return 0;
}
return (stubVMAddr & (-4096)) + adrpValue*4096 + addValue;
}
#endif
template <typename P>
void StubOptimizer<P>::buildStubMap(const std::unordered_set<std::string>& neverStubEliminate)
{
// find all stubs and lazy pointers
const macho_nlist<P>* symbolTable = (const macho_nlist<P>*)(&_linkeditBias[_symTabCmd->symoff()]);
const char* symbolStrings = (char*)(&_linkeditBias[_symTabCmd->stroff()]);
const uint32_t* const indirectTable = (uint32_t*)(&_linkeditBias[_dynSymTabCmd->indirectsymoff()]);
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)_mh + sizeof(macho_header<P>));
const uint32_t cmd_count = _mh->ncmds();
const macho_load_command<P>* cmd = cmds;
for (uint32_t i = 0; i < cmd_count; ++i) {
if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)seg + sizeof(macho_segment_command<P>));
macho_section<P>* const sectionsEnd = §ionsStart[seg->nsects()];
for(macho_section<P>* sect = sectionsStart; sect < sectionsEnd; ++sect) {
if ( sect->size() == 0 )
continue;
unsigned sectionType = (sect->flags() & SECTION_TYPE);
const uint32_t indirectTableOffset = sect->reserved1();
if ( sectionType == S_SYMBOL_STUBS ) {
const uint32_t stubSize = sect->reserved2();
_stubCount = (uint32_t)(sect->size() / stubSize);
pint_t stubVMAddr = (pint_t)sect->addr();
for (uint32_t j=0; j < _stubCount; ++j, stubVMAddr += stubSize) {
uint32_t symbolIndex = E::get32(indirectTable[indirectTableOffset + j]);
switch ( symbolIndex ) {
case INDIRECT_SYMBOL_ABS:
case INDIRECT_SYMBOL_LOCAL:
case INDIRECT_SYMBOL_ABS | INDIRECT_SYMBOL_LOCAL:
break;
default:
if ( symbolIndex >= _symTabCmd->nsyms() ) {
_diagnostics.warning("symbol index out of range (%d of %d) for stub at addr 0x%0llX in %s",
symbolIndex, _symTabCmd->nsyms(), (uint64_t)stubVMAddr, _dylibID);
continue;
}
const macho_nlist<P>* sym = &symbolTable[symbolIndex];
uint32_t stringOffset = sym->n_strx();
if ( stringOffset > _symTabCmd->strsize() ) {
_diagnostics.warning("symbol string offset out of range (%u of %u) for stub at addr 0x%0llX in %s",
stringOffset, sym->n_strx(), (uint64_t)stubVMAddr, _dylibID);
continue;
}
const char* symName = &symbolStrings[stringOffset];
if ( neverStubEliminate.count(symName) ) {
//fprintf(stderr, "stubVMAddr=0x%llX, not bypassing stub to %s in %s because target is interposable\n", (uint64_t)stubVMAddr, symName, _dylibID);
_stubsLeftInterposable++;
continue;
}
const uint8_t* stubInstrs = (uint8_t*)(long)stubVMAddr + _cacheSlide;
pint_t targetLPAddr = 0;
switch ( _mh->cputype() ) {
case CPU_TYPE_ARM64:
#if SUPPORT_ARCH_arm64e
if (cpuSubtype() == CPU_SUBTYPE_ARM64E)
targetLPAddr = (pint_t)lazyPointerAddrFromArm64eStub(stubInstrs, stubVMAddr);
else
#endif
targetLPAddr = (pint_t)lazyPointerAddrFromArm64Stub(stubInstrs, stubVMAddr);
break;
#if SUPPORT_ARCH_arm64_32
case CPU_TYPE_ARM64_32:
if (cpuSubtype() == CPU_SUBTYPE_ARM64_32_V8)
targetLPAddr = (pint_t)lazyPointerAddrFromArm64_32Stub(stubInstrs, stubVMAddr);
break;
#endif
case CPU_TYPE_ARM:
targetLPAddr = (pint_t)lazyPointerAddrFromArmStub(stubInstrs, (uint32_t)stubVMAddr);
break;
}
if ( targetLPAddr != 0 )
_stubAddrToLPAddr[stubVMAddr] = targetLPAddr;
break;
}
}
}
else if ( (sectionType == S_LAZY_SYMBOL_POINTERS) || (sectionType == S_NON_LAZY_SYMBOL_POINTERS) ) {
pint_t lpVMAddr;
pint_t* lpContent = (pint_t*)(sect->addr() + _cacheSlide);
uint32_t elementCount = (uint32_t)(sect->size() / sizeof(pint_t));
uint64_t textSegStartAddr = _segCmds[0]->vmaddr();
uint64_t textSegEndAddr = _segCmds[0]->vmaddr() + _segCmds[0]->vmsize();
pint_t lpValue;
const CacheBuilder::DylibSectionCoalescer::OptimizedSection* optimizedSection = nullptr;
if ( !strcmp(sect->sectname(), "__got") )
optimizedSection = this->_coalescedGOTs;
else if ( !strcmp(sect->sectname(), "__auth_got") )
optimizedSection = this->_coalescedAuthGOTs;
for (uint32_t j=0; j < elementCount; ++j) {
uint32_t symbolIndex = E::get32(indirectTable[indirectTableOffset + j]);
switch ( symbolIndex ) {
case INDIRECT_SYMBOL_ABS:
case INDIRECT_SYMBOL_LOCAL:
case INDIRECT_SYMBOL_LOCAL|INDIRECT_SYMBOL_ABS:
break;
default:
lpValue = (pint_t)P::getP(lpContent[j]);
lpVMAddr = (pint_t)sect->addr() + j * sizeof(pint_t);
if ( symbolIndex >= _symTabCmd->nsyms() ) {
_diagnostics.warning("symbol index out of range (%d of %d) for lazy pointer at addr 0x%0llX in %s",
symbolIndex, _symTabCmd->nsyms(), (uint64_t)lpVMAddr, _dylibID);
continue;
}
const macho_nlist<P>* sym = &symbolTable[symbolIndex];
uint32_t stringOffset = sym->n_strx();
if ( stringOffset > _symTabCmd->strsize() ) {
_diagnostics.warning("symbol string offset out of range (%u of %u) for lazy pointer at addr 0x%0llX in %s",
stringOffset, sym->n_strx(), (uint64_t)lpVMAddr, _dylibID);
continue;
}
const char* symName = &symbolStrings[stringOffset];
// GOT uniquing redirected the stub to a new GOT, so it won't point to this one
// Additionally, this GOT has been set to null, so that any accidental uses would be crashes
// If this is a rewritten GOT, change it to point to the new GOT
if ( optimizedSection != nullptr ) {
uint32_t sectionOffset = (uint32_t)(j * sizeof(pint_t));
auto it = optimizedSection->offsetMap.find(sectionOffset);
if ( it != optimizedSection->offsetMap.end() ) {
uint64_t cacheGOTVMAddr = optimizedSection->subCacheSection->bufferVMAddr + it->second;
lpVMAddr = (pint_t)cacheGOTVMAddr;
// Load the GOT in the cache to see where points to
const uint8_t* cacheGOTLocation = optimizedSection->subCacheSection->bufferAddr + it->second;
lpValue = (pint_t)P::getP(*(pint_t*)cacheGOTLocation);
}
}
if ( (lpValue > textSegStartAddr) && (lpValue< textSegEndAddr) ) {
//fprintf(stderr, "skipping lazy pointer at 0x%0lX to %s in %s because target is within dylib\n", (long)lpVMAddr, symName, _dylibID);
}
else if ( (sizeof(pint_t) == 8) && ((lpValue % 4) != 0) ) {
// Only warn on lazy pointers which correspond to call targets
if ( sectionType == S_LAZY_SYMBOL_POINTERS ) {
_diagnostics.warning("lazy pointer at 0x%0llX does not point to 4-byte aligned address(0x%0llX) for symbol '%s' in %s",
(uint64_t)lpVMAddr, (uint64_t)lpValue, symName, _dylibID);
}
}
else {
_lpAddrToTargetAddr[lpVMAddr] = lpValue;
_targetAddrToName[lpValue] = symName;
}
break;
}
}
}
}
}
cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
}
}
template <typename P>
void StubOptimizer<P>::forEachCallSiteToAStub(CallSiteHandler handler)
{
if (_diagnostics.hasError())
return;
const uint8_t* infoStart = &_linkeditBias[_splitSegInfoCmd->dataoff()];
const uint8_t* infoEnd = &infoStart[_splitSegInfoCmd->datasize()];
if ( *infoStart++ != DYLD_CACHE_ADJ_V2_FORMAT ) {
_diagnostics.error("malformed split seg info in %s", _dylibID);
return;
}
uint8_t* textSectionContent = (uint8_t*)(_textSection->addr() + _cacheSlide);
// Whole :== <count> FromToSection+
// FromToSection :== <from-sect-index> <to-sect-index> <count> ToOffset+
// ToOffset :== <to-sect-offset-delta> <count> FromOffset+
// FromOffset :== <kind> <count> <from-sect-offset-delta>
const uint8_t* p = infoStart;
uint64_t sectionCount = read_uleb128(p, infoEnd);
for (uint64_t i=0; i < sectionCount; ++i) {
uint64_t fromSectionIndex = read_uleb128(p, infoEnd);
uint64_t toSectionIndex = read_uleb128(p, infoEnd);
uint64_t toOffsetCount = read_uleb128(p, infoEnd);
uint64_t toSectionOffset = 0;
for (uint64_t j=0; j < toOffsetCount; ++j) {
uint64_t toSectionDelta = read_uleb128(p, infoEnd);
uint64_t fromOffsetCount = read_uleb128(p, infoEnd);
toSectionOffset += toSectionDelta;
for (uint64_t k=0; k < fromOffsetCount; ++k) {
uint64_t kind = read_uleb128(p, infoEnd);
if ( kind > 13 ) {
_diagnostics.error("bad kind (%llu) value in %s\n", kind, _dylibID);
}
uint64_t fromSectDeltaCount = read_uleb128(p, infoEnd);
uint64_t fromSectionOffset = 0;
for (uint64_t l=0; l < fromSectDeltaCount; ++l) {
uint64_t delta = read_uleb128(p, infoEnd);
fromSectionOffset += delta;
if ( (fromSectionIndex == _textSectionIndex) && (toSectionIndex == _stubSectionIndex) ) {
uint32_t* instrPtr = (uint32_t*)(textSectionContent + fromSectionOffset);
uint64_t instrAddr = _textSection->addr() + fromSectionOffset;
uint64_t stubAddr = _stubSection->addr() + toSectionOffset;
uint32_t instruction = E::get32(*instrPtr);
_branchToStubCount++;
if ( handler(kind, instrAddr, stubAddr, instruction) ) {
E::set32(*instrPtr, instruction);
}
}
}
}
}
}
}
/// Extract displacement from a thumb b/bl/blx instruction.
template <typename P>
int32_t StubOptimizer<P>::getDisplacementFromThumbBranch(uint32_t instruction, uint32_t instrAddr)
{
bool is_blx = ((instruction & 0xD000F800) == 0xC000F000);
uint32_t s = (instruction >> 10) & 0x1;
uint32_t j1 = (instruction >> 29) & 0x1;
uint32_t j2 = (instruction >> 27) & 0x1;
uint32_t imm10 = instruction & 0x3FF;
uint32_t imm11 = (instruction >> 16) & 0x7FF;
uint32_t i1 = (j1 == s);
uint32_t i2 = (j2 == s);
uint32_t dis = (s << 24) | (i1 << 23) | (i2 << 22) | (imm10 << 12) | (imm11 << 1);
int32_t sdis = dis;
int32_t result = s ? (sdis | 0xFE000000) : sdis;
if ( is_blx && (instrAddr & 0x2) ) {
// The thumb blx instruction always has low bit of imm11 as zero. The way
// a 2-byte aligned blx can branch to a 4-byte aligned ARM target is that
// the blx instruction always 4-byte aligns the pc before adding the
// displacement from the blx. We must emulate that when decoding this.
result -= 2;
}
return result;
}
/// Update a thumb b/bl/blx instruction, switching bl <-> blx as needed.
template <typename P>
uint32_t StubOptimizer<P>::setDisplacementInThumbBranch(uint32_t instruction, uint32_t instrAddr,
int32_t displacement, bool targetIsThumb) {
if ( (displacement > 16777214) || (displacement < (-16777216)) ) {
_diagnostics.error("thumb branch out of range at 0x%0X in %s", instrAddr, _dylibID);
return 0;
}
bool is_bl = ((instruction & 0xD000F800) == 0xD000F000);
bool is_blx = ((instruction & 0xD000F800) == 0xC000F000);
bool is_b = ((instruction & 0xD000F800) == 0x9000F000);
uint32_t newInstruction = (instruction & 0xD000F800);
if (is_bl || is_blx) {
if (targetIsThumb) {
newInstruction = 0xD000F000; // Use bl
}
else {
newInstruction = 0xC000F000; // Use blx
// See note in getDisplacementFromThumbBranch() about blx.
if (instrAddr & 0x2)
displacement += 2;
}
}
else if (is_b) {
if ( !targetIsThumb ) {
_diagnostics.error("no pc-rel thumb branch instruction that switches to arm mode at 0x%0X in %s", instrAddr, _dylibID);
return 0;
}
}
else {
_diagnostics.error("not b/bl/blx at 0x%0X in %s", instrAddr, _dylibID);
return 0;
}
uint32_t s = (uint32_t)(displacement >> 24) & 0x1;
uint32_t i1 = (uint32_t)(displacement >> 23) & 0x1;
uint32_t i2 = (uint32_t)(displacement >> 22) & 0x1;
uint32_t imm10 = (uint32_t)(displacement >> 12) & 0x3FF;
uint32_t imm11 = (uint32_t)(displacement >> 1) & 0x7FF;
uint32_t j1 = (i1 == s);
uint32_t j2 = (i2 == s);
uint32_t nextDisp = (j1 << 13) | (j2 << 11) | imm11;
uint32_t firstDisp = (s << 10) | imm10;
newInstruction |= (nextDisp << 16) | firstDisp;
return newInstruction;
}
template <typename P>
void StubOptimizer<P>::optimizeArmCallSites(std::unordered_map<uint64_t, uint64_t>& targetAddrToOptStubAddr)
{
forEachCallSiteToAStub([&](uint8_t kind, uint64_t callSiteAddr, uint64_t stubAddr, uint32_t& instruction) -> bool {
if ( kind == DYLD_CACHE_ADJ_V2_THUMB_BR22 ) {
bool is_bl = ((instruction & 0xD000F800) == 0xD000F000);
bool is_blx = ((instruction & 0xD000F800) == 0xC000F000);
bool is_b = ((instruction & 0xD000F800) == 0x9000F000);
if ( !is_bl && !is_blx && !is_b ){
_diagnostics.warning("non-branch instruction at 0x%0llX in %s", callSiteAddr, _dylibID);
return false;
}
int32_t brDelta = getDisplacementFromThumbBranch(instruction, (uint32_t)callSiteAddr);
pint_t targetAddr = (pint_t)callSiteAddr + 4 + brDelta;
if ( targetAddr != stubAddr ) {
_diagnostics.warning("stub target mismatch at callsite 0x%0llX in %s", callSiteAddr, _dylibID);
return false;
}
// ignore branch if not to a known stub
const auto& pos = _stubAddrToLPAddr.find(targetAddr);
if ( pos == _stubAddrToLPAddr.end() )
return false;
// ignore branch if lazy pointer is not known (resolver or interposable)
uint64_t lpAddr = pos->second;
const auto& pos2 = _lpAddrToTargetAddr.find((pint_t)lpAddr);
if ( pos2 == _lpAddrToTargetAddr.end() )
return false;
uint64_t finalTargetAddr = pos2->second;
int64_t deltaToFinalTarget = finalTargetAddr - (callSiteAddr + 4);
// if final target within range, change to branch there directly
if ( (deltaToFinalTarget > -b16MegLimit) && (deltaToFinalTarget < b16MegLimit) ) {
bool targetIsThumb = (finalTargetAddr & 1);
instruction = setDisplacementInThumbBranch(instruction, (uint32_t)callSiteAddr, (int32_t)deltaToFinalTarget, targetIsThumb);
if (_diagnostics.hasError())
return false;
_branchOptimizedToDirectCount++;
return true;
}
// try to re-use an existing optimized stub
const auto& pos3 = targetAddrToOptStubAddr.find(finalTargetAddr);
if ( pos3 != targetAddrToOptStubAddr.end() ) {
uint64_t existingStub = pos3->second;
if ( existingStub != stubAddr ) {
int64_t deltaToOptStub = existingStub - (callSiteAddr + 4);
if ( (deltaToOptStub > -b16MegLimit) && (deltaToOptStub < b16MegLimit) ) {
bool targetIsThumb = (existingStub & 1);
instruction = setDisplacementInThumbBranch(instruction, (uint32_t)callSiteAddr, (int32_t)deltaToOptStub, targetIsThumb);
if (_diagnostics.hasError())
return false;
_branchToReUsedOptimizedStubCount++;
return true;
}
}
}
// leave as BL to stub, but optimize the stub
_stubsToOptimize.insert(stubAddr);
targetAddrToOptStubAddr[finalTargetAddr] = stubAddr;
_branchToOptimizedStubCount++;
return false;
}
else if ( kind == DYLD_CACHE_ADJ_V2_ARM_BR24 ) {
// too few of these to be worth trying to optimize
}
return false;
});
if (_diagnostics.hasError())
return;
}
template <typename P>
void StubOptimizer<P>::optimizeArmStubs()
{
for (const auto& stubEntry : _stubAddrToLPAddr) {
pint_t stubVMAddr = stubEntry.first;
pint_t lpVMAddr = stubEntry.second;
const auto& pos = _lpAddrToTargetAddr.find(lpVMAddr);
if ( pos == _lpAddrToTargetAddr.end() )
return;
pint_t targetVMAddr = pos->second;
int32_t delta = (int32_t)(targetVMAddr - (stubVMAddr + 12));
uint32_t* stubInstructions = (uint32_t*)((uint8_t*)(long)stubVMAddr + _cacheSlide);
assert(stubInstructions[0] == 0xe59fc004);
stubInstructions[0] = 0xe59fc000; // ldr ip, L0
stubInstructions[1] = 0xe08ff00c; // add pc, pc, ip
stubInstructions[2] = delta; // L0: .long xxxx
stubInstructions[3] = 0xe7ffdefe; // trap
_stubOptimizedCount++;
}
}
template <typename P>
void StubOptimizer<P>::optimizeArm64Stubs()
{
for (const uint64_t stubVMAddr : _stubsToOptimize ) {
pint_t lpVMAddr = _stubAddrToLPAddr[(pint_t)stubVMAddr];
const auto& pos = _lpAddrToTargetAddr.find(lpVMAddr);
if ( pos == _lpAddrToTargetAddr.end() )
return;
pint_t targetVMAddr = pos->second;
int64_t adrpDelta = (targetVMAddr & -4096) - (stubVMAddr & -4096);
// Note: ADRP/ADD can only span +/-4GB
uint32_t* stubInstructions = (uint32_t*)((uint8_t*)(long)stubVMAddr + _cacheSlide);
bool rightInstr1 = ((stubInstructions[0] & 0x9F00001F) == 0x90000010); // ADRP X16, lp@page
bool rightInstr2 = ((stubInstructions[1] & 0xFFC003FF) == 0xF9400210); // LDR X16, [X16, lp@pageoff]
bool rightInstr3 = (stubInstructions[2] == 0xD61F0200); // BR X16
if ( rightInstr1 && rightInstr2 && rightInstr3 ) {
uint32_t immhi = (adrpDelta >> 9) & (0x00FFFFE0);
uint32_t immlo = (adrpDelta << 17) & (0x60000000);
uint32_t newADRP = (0x90000010) | immlo | immhi;
uint32_t off12 = (targetVMAddr & 0xFFF);
uint32_t newADD = (0x91000210) | (off12 << 10);
stubInstructions[0] = newADRP; // ADRP X16, target@page
stubInstructions[1] = newADD; // ADD X16, X16, target@pageoff
stubInstructions[2] = 0xD61F0200; // BR X16
_stubOptimizedCount++;
}
}
}
#if SUPPORT_ARCH_arm64e
template <typename P>
void StubOptimizer<P>::optimizeArm64eStubs()
{
for (const uint64_t stubVMAddr : _stubsToOptimize ) {
pint_t lpVMAddr = _stubAddrToLPAddr[(pint_t)stubVMAddr];
const auto& pos = _lpAddrToTargetAddr.find(lpVMAddr);
if ( pos == _lpAddrToTargetAddr.end() )
return;
pint_t targetVMAddr = pos->second;
int64_t adrpDelta = (targetVMAddr & -4096) - (stubVMAddr & -4096);
// Note: ADRP/ADD can only span +/-4GB
uint32_t* stubInstructions = (uint32_t*)((uint8_t*)(long)stubVMAddr + _cacheSlide);
bool rightInstr1 = ((stubInstructions[0] & 0x9F00001F) == 0x90000011); // ADRP X17, lp@page
bool rightInstr2 = ((stubInstructions[1] & 0xFFC003FF) == 0x91000231); // ADD X17, [X17, lp@pageoff]
bool rightInstr3 = (stubInstructions[2] == 0xF9400230); // LDR X16, [X17]
bool rightInstr4 = (stubInstructions[3] == 0xD71F0A11); // BRAA X16, X17
if ( rightInstr1 && rightInstr2 && rightInstr3 && rightInstr4) {
uint32_t immhi = (adrpDelta >> 9) & (0x00FFFFE0);
uint32_t immlo = (adrpDelta << 17) & (0x60000000);
uint32_t newADRP = (0x90000010) | immlo | immhi;
uint32_t off12 = (targetVMAddr & 0xFFF);
uint32_t newADD = (0x91000210) | (off12 << 10);
stubInstructions[0] = newADRP; // ADRP X16, target@page
stubInstructions[1] = newADD; // ADD X16, X16, target@pageoff
stubInstructions[2] = 0xD61F0200; // BR X16
stubInstructions[3] = 0xD4200020; // TRAP
_stubOptimizedCount++;
}
}
}
#endif
#if SUPPORT_ARCH_arm64_32
template <typename P>
void StubOptimizer<P>::optimizeArm64_32Stubs()
{
for (const uint64_t stubVMAddr : _stubsToOptimize ) {
pint_t lpVMAddr = _stubAddrToLPAddr[(pint_t)stubVMAddr];
const auto& pos = _lpAddrToTargetAddr.find(lpVMAddr);
if ( pos == _lpAddrToTargetAddr.end() )
return;
pint_t targetVMAddr = pos->second;
int64_t adrpDelta = (targetVMAddr & -4096) - (stubVMAddr & -4096);
uint32_t* stubInstructions = (uint32_t*)((uint8_t*)(long)stubVMAddr + _cacheSlide);
bool rightInstr1 = ((stubInstructions[0] & 0x9F00001F) == 0x90000010); // ADRP X16, lp@page
bool rightInstr2 = ((stubInstructions[1] & 0xFFC003FF) == 0xB9400210); // LDR W16, [X16, lp@pageoff]
bool rightInstr3 = (stubInstructions[2] == 0xD61F0200); // BR X16
if ( rightInstr1 && rightInstr2 && rightInstr3 ) {
uint32_t immhi = (adrpDelta >> 9) & (0x00FFFFE0);
uint32_t immlo = (adrpDelta << 17) & (0x60000000);
uint32_t newADRP = (0x90000010) | immlo | immhi;
uint32_t off12 = (targetVMAddr & 0xFFF);
uint32_t newADD = (0x91000210) | (off12 << 10);
stubInstructions[0] = newADRP; // ADRP X16, target@page
stubInstructions[1] = newADD; // ADD X16, X16, target@pageoff
stubInstructions[2] = 0xD61F0200; // BR X16
_stubOptimizedCount++;
}
}
}
#endif
template <typename P>
void StubOptimizer<P>::optimizeArm64CallSites(std::unordered_map<uint64_t, uint64_t>& targetAddrToOptStubAddr)
{
forEachCallSiteToAStub([&](uint8_t kind, uint64_t callSiteAddr, uint64_t stubAddr, uint32_t& instruction) -> bool {
if ( kind != DYLD_CACHE_ADJ_V2_ARM64_BR26 )
return false;
// skip all but BL or B
if ( (instruction & 0x7C000000) != 0x14000000 )
return false;
// compute target of branch instruction
int32_t brDelta = (instruction & 0x03FFFFFF) << 2;
if ( brDelta & 0x08000000 )
brDelta |= 0xF0000000;
uint64_t targetAddr = callSiteAddr + (int64_t)brDelta;
if ( targetAddr != stubAddr ) {
_diagnostics.warning("stub target mismatch");
return false;
}
// ignore branch if not to a known stub
const auto& pos = _stubAddrToLPAddr.find((pint_t)targetAddr);
if ( pos == _stubAddrToLPAddr.end() )
return false;
// ignore branch if lazy pointer is not known (resolver or interposable)
uint64_t lpAddr = pos->second;
const auto& pos2 = _lpAddrToTargetAddr.find((pint_t)lpAddr);
if ( pos2 == _lpAddrToTargetAddr.end() )
return false;
uint64_t finalTargetAddr = pos2->second;
int64_t deltaToFinalTarget = finalTargetAddr - callSiteAddr;
// if final target within range, change to branch there directly
if ( (deltaToFinalTarget > -b128MegLimit) && (deltaToFinalTarget < b128MegLimit) ) {
instruction= (instruction & 0xFC000000) | ((deltaToFinalTarget >> 2) & 0x03FFFFFF);
_branchOptimizedToDirectCount++;
return true;
}
// try to re-use an existing optimized stub
const auto& pos3 = targetAddrToOptStubAddr.find((pint_t)finalTargetAddr);
if ( pos3 != targetAddrToOptStubAddr.end() ) {
uint64_t existingStub = pos3->second;
if ( existingStub != stubAddr ) {
int64_t deltaToOptStub = existingStub - callSiteAddr;
if ( (deltaToOptStub > -b128MegLimit) && (deltaToOptStub < b128MegLimit) ) {
instruction = (instruction & 0xFC000000) | ((deltaToOptStub >> 2) & 0x03FFFFFF);
_branchToReUsedOptimizedStubCount++;
return true;
}
}
}
// leave as BL to stub, but optimize the stub
_stubsToOptimize.insert(stubAddr);
targetAddrToOptStubAddr[(pint_t)finalTargetAddr] = (pint_t)stubAddr;
_branchToOptimizedStubCount++;
return false;
});
if (_diagnostics.hasError())
return;
}
template <typename P>
void StubOptimizer<P>::redirectArm64_32CallSitesToIslands()
{
forEachCallSiteToAStub([&](uint8_t kind, uint64_t callSiteAddr, uint64_t stubAddr, uint32_t& instruction) -> bool {
if ( kind != DYLD_CACHE_ADJ_V2_ARM64_BR26 )
return false;
// skip all but BL or B
if ( (instruction & 0x7C000000) != 0x14000000 )
return false;
// compute target of branch instruction
int32_t brDelta = (instruction & 0x03FFFFFF) << 2;
if ( brDelta & 0x08000000 )
brDelta |= 0xF0000000;
uint64_t targetAddr = callSiteAddr + (int64_t)brDelta;
if ( targetAddr != stubAddr ) {
_diagnostics.warning("stub target mismatch");
return false;
}
// ignore branch if not to a known stub
const auto& pos = _stubAddrToLPAddr.find((pint_t)targetAddr);
if ( pos == _stubAddrToLPAddr.end() )
return false;
uint64_t lpAddr = pos->second;
// ignore branch if lazy pointer is not known (resolver or interposable)
const auto& posB = _lpAddrToTargetAddr.find((pint_t)lpAddr);
if ( posB == _lpAddrToTargetAddr.end() ) {
return false;
}
uint64_t finalTargetAddr = posB->second;
// change BL target to stub island
const auto& posC = _stubsToIslands.find(stubAddr);
if ( posC == _stubsToIslands.end() ) {
_diagnostics.error("could not find stub in islands");
return false;
}
uint64_t newStubAddr = posC->second.first;
uint8_t* devStubsBuffer = posC->second.second;
int64_t deltaToNewStub = newStubAddr - callSiteAddr;
if ( (deltaToNewStub <= -b128MegLimit) || (deltaToNewStub >= b128MegLimit) ) {
_diagnostics.error("%s call could not reach stub island at offset 0x%llx", this->dylibID(), deltaToNewStub);
return false;
}
// customer
int64_t adrpDelta = (finalTargetAddr & -4096) - ((uint64_t)newStubAddr & -4096);
uint32_t immhi = (adrpDelta >> 9) & (0x00FFFFE0);
uint32_t immlo = (adrpDelta << 17) & (0x60000000);
uint32_t newADRP = (0x90000010) | immlo | immhi;
uint32_t off12 = (finalTargetAddr & 0xFFF);
uint32_t newADD = (0x91000210) | (off12 << 10);
uint32_t* stubInstructions = (uint32_t*)(newStubAddr + _cacheSlide);
stubInstructions[0] = newADRP; // ADRP X16, target@page
stubInstructions[1] = newADD; // ADD X16, X16, target@pageoff
stubInstructions[2] = 0xD61F0200; // BR X16
// dev
adrpDelta = (lpAddr & -4096) - ((uint64_t)newStubAddr & -4096);
immhi = (adrpDelta >> 9) & (0x00FFFFE0);
immlo = (adrpDelta << 17) & (0x60000000);
newADRP = (0x90000010) | immlo | immhi;
off12 = (lpAddr & 0xFFF) >> 2;
uint32_t newLDR = (0xB9400210) | (off12 << 10);
stubInstructions = (uint32_t*)devStubsBuffer;
stubInstructions[0] = newADRP; // ADRP X16, lazy_pointer@page
stubInstructions[1] = newLDR; // LDR W16, [X16, lazy_pointer@pageoff]
stubInstructions[2] = 0xD61F0200; // BR X16
return true;
});
}
template <typename P>
void StubOptimizer<P>::redirectArm64CallSitesToIslands()
{
forEachCallSiteToAStub([&](uint8_t kind, uint64_t callSiteAddr, uint64_t stubAddr, uint32_t& instruction) -> bool {
if ( kind != DYLD_CACHE_ADJ_V2_ARM64_BR26 )
return false;
// skip all but BL or B
if ( (instruction & 0x7C000000) != 0x14000000 )
return false;
// compute target of branch instruction
int32_t brDelta = (instruction & 0x03FFFFFF) << 2;
if ( brDelta & 0x08000000 )
brDelta |= 0xF0000000;
uint64_t targetAddr = callSiteAddr + (int64_t)brDelta;
if ( targetAddr != stubAddr ) {
_diagnostics.warning("stub target mismatch");
return false;
}
// ignore branch if not to a known stub
const auto& pos = _stubAddrToLPAddr.find((pint_t)targetAddr);
if ( pos == _stubAddrToLPAddr.end() )
return false;
uint64_t lpAddr = pos->second;
// ignore branch if lazy pointer is not known (resolver or interposable)
const auto& posB = _lpAddrToTargetAddr.find((pint_t)lpAddr);
if ( posB == _lpAddrToTargetAddr.end() ) {
return false;
}
uint64_t finalTargetAddr = posB->second;
// change BL target to stub island
const auto& posC = _stubsToIslands.find(stubAddr);
if ( posC == _stubsToIslands.end() ) {
_diagnostics.error("could not find stub in islands");
return false;
}
uint64_t newStubAddr = posC->second.first;
uint8_t* devStubsBuffer = posC->second.second;
int64_t deltaToNewStub = newStubAddr - callSiteAddr;
if ( (deltaToNewStub <= -b128MegLimit) || (deltaToNewStub >= b128MegLimit) ) {
_diagnostics.error("%s call could not reach stub island at offset 0x%llx", this->dylibID(), deltaToNewStub);