+++ /dev/null
-/*******************************************************************************
- mach_override.c
- Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
- Some rights reserved: <http://opensource.org/licenses/mit-license.php>
-
- ***************************************************************************/
-#ifdef __APPLE__
-
-#include "mach_override.h"
-
-#include <mach-o/dyld.h>
-#include <mach/mach_host.h>
-#include <mach/mach_init.h>
-#include <mach/vm_map.h>
-#include <sys/mman.h>
-
-#include <CoreServices/CoreServices.h>
-
-//#define DEBUG_DISASM 1
-#undef DEBUG_DISASM
-
-/**************************
-*
-* Constants
-*
-**************************/
-#pragma mark -
-#pragma mark (Constants)
-
-#if defined(__ppc__) || defined(__POWERPC__)
-
-static
-long kIslandTemplate[] = {
- 0x9001FFFC, // stw r0,-4(SP)
- 0x3C00DEAD, // lis r0,0xDEAD
- 0x6000BEEF, // ori r0,r0,0xBEEF
- 0x7C0903A6, // mtctr r0
- 0x8001FFFC, // lwz r0,-4(SP)
- 0x60000000, // nop ; optionally replaced
- 0x4E800420 // bctr
-};
-
-#define kAddressHi 3
-#define kAddressLo 5
-#define kInstructionHi 10
-#define kInstructionLo 11
-
-#elif defined(__i386__)
-
-#define kOriginalInstructionsSize 16
-
-static
-unsigned char kIslandTemplate[] = {
- // kOriginalInstructionsSize nop instructions so that we
- // should have enough space to host original instructions
- 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
- 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
- // Now the real jump instruction
- 0xE9, 0xEF, 0xBE, 0xAD, 0xDE
-};
-
-#define kInstructions 0
-#define kJumpAddress kInstructions + kOriginalInstructionsSize + 1
-#elif defined(__x86_64__)
-
-#define kOriginalInstructionsSize 32
-
-#define kJumpAddress kOriginalInstructionsSize + 6
-
-static
-unsigned char kIslandTemplate[] = {
- // kOriginalInstructionsSize nop instructions so that we
- // should have enough space to host original instructions
- 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
- 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
- 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
- 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
- // Now the real jump instruction
- 0xFF, 0x25, 0x00, 0x00, 0x00, 0x00,
- 0x00, 0x00, 0x00, 0x00,
- 0x00, 0x00, 0x00, 0x00
-};
-
-#endif
-
-#define kAllocateHigh 1
-#define kAllocateNormal 0
-
-/**************************
-*
-* Data Types
-*
-**************************/
-#pragma mark -
-#pragma mark (Data Types)
-
-typedef struct {
- char instructions[sizeof(kIslandTemplate)];
- int allocatedHigh;
-} BranchIsland;
-
-/**************************
-*
-* Funky Protos
-*
-**************************/
-#pragma mark -
-#pragma mark (Funky Protos)
-
-
- static mach_error_t
-allocateBranchIsland(
- BranchIsland **island,
- int allocateHigh,
- void *originalFunctionAddress);
-
- static mach_error_t
-freeBranchIsland(
- BranchIsland *island );
-
- static mach_error_t
-defaultIslandMalloc(
- void **ptr, size_t unused_size, void *hint);
-
- static mach_error_t
-defaultIslandFree(
- void *ptr);
-
-#if defined(__ppc__) || defined(__POWERPC__)
- static mach_error_t
-setBranchIslandTarget(
- BranchIsland *island,
- const void *branchTo,
- long instruction );
-#endif
-
-#if defined(__i386__) || defined(__x86_64__)
-static mach_error_t
-setBranchIslandTarget_i386(
- BranchIsland *island,
- const void *branchTo,
- char* instructions );
-// Can't be made static because there's no C implementation for atomic_mov64
-// on i386.
-void
-atomic_mov64(
- uint64_t *targetAddress,
- uint64_t value ) __attribute__((visibility("hidden")));
-
- static Boolean
-eatKnownInstructions(
- unsigned char *code,
- uint64_t *newInstruction,
- int *howManyEaten,
- char *originalInstructions,
- int *originalInstructionCount,
- uint8_t *originalInstructionSizes );
-
- static void
-fixupInstructions(
- void *originalFunction,
- void *escapeIsland,
- void *instructionsToFix,
- int instructionCount,
- uint8_t *instructionSizes );
-
-#ifdef DEBUG_DISASM
- static void
-dump16Bytes(
- void *ptr);
-#endif // DEBUG_DISASM
-#endif
-
-/*******************************************************************************
-*
-* Interface
-*
-*******************************************************************************/
-#pragma mark -
-#pragma mark (Interface)
-
-#if defined(__i386__) || defined(__x86_64__)
-static mach_error_t makeIslandExecutable(void *address) {
- mach_error_t err = err_none;
- vm_size_t pageSize;
- host_page_size( mach_host_self(), &pageSize );
- uintptr_t page = (uintptr_t)address & ~(uintptr_t)(pageSize-1);
- int e = err_none;
- e |= mprotect((void *)page, pageSize, PROT_EXEC | PROT_READ | PROT_WRITE);
- e |= msync((void *)page, pageSize, MS_INVALIDATE );
- if (e) {
- err = err_cannot_override;
- }
- return err;
-}
-#endif
-
- static mach_error_t
-defaultIslandMalloc(
- void **ptr, size_t unused_size, void *hint) {
- return allocateBranchIsland( (BranchIsland**)ptr, kAllocateHigh, hint );
-}
- static mach_error_t
-defaultIslandFree(
- void *ptr) {
- return freeBranchIsland(ptr);
-}
-
- mach_error_t
-__asan_mach_override_ptr(
- void *originalFunctionAddress,
- const void *overrideFunctionAddress,
- void **originalFunctionReentryIsland )
-{
- return __asan_mach_override_ptr_custom(originalFunctionAddress,
- overrideFunctionAddress,
- originalFunctionReentryIsland,
- defaultIslandMalloc,
- defaultIslandFree);
-}
-
- mach_error_t
-__asan_mach_override_ptr_custom(
- void *originalFunctionAddress,
- const void *overrideFunctionAddress,
- void **originalFunctionReentryIsland,
- island_malloc *alloc,
- island_free *dealloc)
-{
- assert( originalFunctionAddress );
- assert( overrideFunctionAddress );
-
- // this addresses overriding such functions as AudioOutputUnitStart()
- // test with modified DefaultOutputUnit project
-#if defined(__x86_64__)
- for(;;){
- if(*(uint16_t*)originalFunctionAddress==0x25FF) // jmp qword near [rip+0x????????]
- originalFunctionAddress=*(void**)((char*)originalFunctionAddress+6+*(int32_t *)((uint16_t*)originalFunctionAddress+1));
- else break;
- }
-#elif defined(__i386__)
- for(;;){
- if(*(uint16_t*)originalFunctionAddress==0x25FF) // jmp *0x????????
- originalFunctionAddress=**(void***)((uint16_t*)originalFunctionAddress+1);
- else break;
- }
-#endif
-#ifdef DEBUG_DISASM
- {
- fprintf(stderr, "Replacing function at %p\n", originalFunctionAddress);
- fprintf(stderr, "First 16 bytes of the function: ");
- unsigned char *orig = (unsigned char *)originalFunctionAddress;
- int i;
- for (i = 0; i < 16; i++) {
- fprintf(stderr, "%x ", (unsigned int) orig[i]);
- }
- fprintf(stderr, "\n");
- fprintf(stderr,
- "To disassemble, save the following function as disas.c"
- " and run:\n gcc -c disas.c && gobjdump -d disas.o\n"
- "The first 16 bytes of the original function will start"
- " after four nop instructions.\n");
- fprintf(stderr, "\nvoid foo() {\n asm volatile(\"nop;nop;nop;nop;\");\n");
- int j = 0;
- for (j = 0; j < 2; j++) {
- fprintf(stderr, " asm volatile(\".byte ");
- for (i = 8 * j; i < 8 * (j+1) - 1; i++) {
- fprintf(stderr, "0x%x, ", (unsigned int) orig[i]);
- }
- fprintf(stderr, "0x%x;\");\n", (unsigned int) orig[8 * (j+1) - 1]);
- }
- fprintf(stderr, "}\n\n");
- }
-#endif
-
- long *originalFunctionPtr = (long*) originalFunctionAddress;
- mach_error_t err = err_none;
-
-#if defined(__ppc__) || defined(__POWERPC__)
- // Ensure first instruction isn't 'mfctr'.
- #define kMFCTRMask 0xfc1fffff
- #define kMFCTRInstruction 0x7c0903a6
-
- long originalInstruction = *originalFunctionPtr;
- if( !err && ((originalInstruction & kMFCTRMask) == kMFCTRInstruction) )
- err = err_cannot_override;
-#elif defined(__i386__) || defined(__x86_64__)
- int eatenCount = 0;
- int originalInstructionCount = 0;
- char originalInstructions[kOriginalInstructionsSize];
- uint8_t originalInstructionSizes[kOriginalInstructionsSize];
- uint64_t jumpRelativeInstruction = 0; // JMP
-
- Boolean overridePossible = eatKnownInstructions ((unsigned char *)originalFunctionPtr,
- &jumpRelativeInstruction, &eatenCount,
- originalInstructions, &originalInstructionCount,
- originalInstructionSizes );
-#ifdef DEBUG_DISASM
- if (!overridePossible) fprintf(stderr, "overridePossible = false @%d\n", __LINE__);
-#endif
- if (eatenCount > kOriginalInstructionsSize) {
-#ifdef DEBUG_DISASM
- fprintf(stderr, "Too many instructions eaten\n");
-#endif
- overridePossible = false;
- }
- if (!overridePossible) err = err_cannot_override;
- if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
-#endif
-
- // Make the original function implementation writable.
- if( !err ) {
- err = vm_protect( mach_task_self(),
- (vm_address_t) originalFunctionPtr, 8, false,
- (VM_PROT_ALL | VM_PROT_COPY) );
- if( err )
- err = vm_protect( mach_task_self(),
- (vm_address_t) originalFunctionPtr, 8, false,
- (VM_PROT_DEFAULT | VM_PROT_COPY) );
- }
- if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
-
- // Allocate and target the escape island to the overriding function.
- BranchIsland *escapeIsland = NULL;
- if( !err )
- err = alloc( (void**)&escapeIsland, sizeof(BranchIsland), originalFunctionAddress );
- if ( err ) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
-
-#if defined(__ppc__) || defined(__POWERPC__)
- if( !err )
- err = setBranchIslandTarget( escapeIsland, overrideFunctionAddress, 0 );
-
- // Build the branch absolute instruction to the escape island.
- long branchAbsoluteInstruction = 0; // Set to 0 just to silence warning.
- if( !err ) {
- long escapeIslandAddress = ((long) escapeIsland) & 0x3FFFFFF;
- branchAbsoluteInstruction = 0x48000002 | escapeIslandAddress;
- }
-#elif defined(__i386__) || defined(__x86_64__)
- if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
-
- if( !err )
- err = setBranchIslandTarget_i386( escapeIsland, overrideFunctionAddress, 0 );
-
- if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
- // Build the jump relative instruction to the escape island
-#endif
-
-
-#if defined(__i386__) || defined(__x86_64__)
- if (!err) {
- uint32_t addressOffset = ((char*)escapeIsland - (char*)originalFunctionPtr - 5);
- addressOffset = OSSwapInt32(addressOffset);
-
- jumpRelativeInstruction |= 0xE900000000000000LL;
- jumpRelativeInstruction |= ((uint64_t)addressOffset & 0xffffffff) << 24;
- jumpRelativeInstruction = OSSwapInt64(jumpRelativeInstruction);
- }
-#endif
-
- // Optionally allocate & return the reentry island. This may contain relocated
- // jmp instructions and so has all the same addressing reachability requirements
- // the escape island has to the original function, except the escape island is
- // technically our original function.
- BranchIsland *reentryIsland = NULL;
- if( !err && originalFunctionReentryIsland ) {
- err = alloc( (void**)&reentryIsland, sizeof(BranchIsland), escapeIsland);
- if( !err )
- *originalFunctionReentryIsland = reentryIsland;
- }
-
-#if defined(__ppc__) || defined(__POWERPC__)
- // Atomically:
- // o If the reentry island was allocated:
- // o Insert the original instruction into the reentry island.
- // o Target the reentry island at the 2nd instruction of the
- // original function.
- // o Replace the original instruction with the branch absolute.
- if( !err ) {
- int escapeIslandEngaged = false;
- do {
- if( reentryIsland )
- err = setBranchIslandTarget( reentryIsland,
- (void*) (originalFunctionPtr+1), originalInstruction );
- if( !err ) {
- escapeIslandEngaged = CompareAndSwap( originalInstruction,
- branchAbsoluteInstruction,
- (UInt32*)originalFunctionPtr );
- if( !escapeIslandEngaged ) {
- // Someone replaced the instruction out from under us,
- // re-read the instruction, make sure it's still not
- // 'mfctr' and try again.
- originalInstruction = *originalFunctionPtr;
- if( (originalInstruction & kMFCTRMask) == kMFCTRInstruction)
- err = err_cannot_override;
- }
- }
- } while( !err && !escapeIslandEngaged );
- }
-#elif defined(__i386__) || defined(__x86_64__)
- // Atomically:
- // o If the reentry island was allocated:
- // o Insert the original instructions into the reentry island.
- // o Target the reentry island at the first non-replaced
- // instruction of the original function.
- // o Replace the original first instructions with the jump relative.
- //
- // Note that on i386, we do not support someone else changing the code under our feet
- if ( !err ) {
- fixupInstructions(originalFunctionPtr, reentryIsland, originalInstructions,
- originalInstructionCount, originalInstructionSizes );
-
- if( reentryIsland )
- err = setBranchIslandTarget_i386( reentryIsland,
- (void*) ((char *)originalFunctionPtr+eatenCount), originalInstructions );
- // try making islands executable before planting the jmp
-#if defined(__x86_64__) || defined(__i386__)
- if( !err )
- err = makeIslandExecutable(escapeIsland);
- if( !err && reentryIsland )
- err = makeIslandExecutable(reentryIsland);
-#endif
- if ( !err )
- atomic_mov64((uint64_t *)originalFunctionPtr, jumpRelativeInstruction);
- }
-#endif
-
- // Clean up on error.
- if( err ) {
- if( reentryIsland )
- dealloc( reentryIsland );
- if( escapeIsland )
- dealloc( escapeIsland );
- }
-
-#ifdef DEBUG_DISASM
- {
- fprintf(stderr, "First 16 bytes of the function after slicing: ");
- unsigned char *orig = (unsigned char *)originalFunctionAddress;
- int i;
- for (i = 0; i < 16; i++) {
- fprintf(stderr, "%x ", (unsigned int) orig[i]);
- }
- fprintf(stderr, "\n");
- }
-#endif
- return err;
-}
-
-/*******************************************************************************
-*
-* Implementation
-*
-*******************************************************************************/
-#pragma mark -
-#pragma mark (Implementation)
-
-/***************************************************************************//**
- Implementation: Allocates memory for a branch island.
-
- @param island <- The allocated island.
- @param allocateHigh -> Whether to allocate the island at the end of the
- address space (for use with the branch absolute
- instruction).
- @result <- mach_error_t
-
- ***************************************************************************/
-
- static mach_error_t
-allocateBranchIsland(
- BranchIsland **island,
- int allocateHigh,
- void *originalFunctionAddress)
-{
- assert( island );
-
- mach_error_t err = err_none;
-
- if( allocateHigh ) {
- vm_size_t pageSize;
- err = host_page_size( mach_host_self(), &pageSize );
- if( !err ) {
- assert( sizeof( BranchIsland ) <= pageSize );
-#if defined(__ppc__) || defined(__POWERPC__)
- vm_address_t first = 0xfeffffff;
- vm_address_t last = 0xfe000000 + pageSize;
-#elif defined(__x86_64__)
- vm_address_t first = ((uint64_t)originalFunctionAddress & ~(uint64_t)(((uint64_t)1 << 31) - 1)) | ((uint64_t)1 << 31); // start in the middle of the page?
- vm_address_t last = 0x0;
-#else
- vm_address_t first = 0xffc00000;
- vm_address_t last = 0xfffe0000;
-#endif
-
- vm_address_t page = first;
- int allocated = 0;
- vm_map_t task_self = mach_task_self();
-
- while( !err && !allocated && page != last ) {
-
- err = vm_allocate( task_self, &page, pageSize, 0 );
- if( err == err_none )
- allocated = 1;
- else if( err == KERN_NO_SPACE ) {
-#if defined(__x86_64__)
- page -= pageSize;
-#else
- page += pageSize;
-#endif
- err = err_none;
- }
- }
- if( allocated )
- *island = (BranchIsland*) page;
- else if( !allocated && !err )
- err = KERN_NO_SPACE;
- }
- } else {
- void *block = malloc( sizeof( BranchIsland ) );
- if( block )
- *island = block;
- else
- err = KERN_NO_SPACE;
- }
- if( !err )
- (**island).allocatedHigh = allocateHigh;
-
- return err;
-}
-
-/***************************************************************************//**
- Implementation: Deallocates memory for a branch island.
-
- @param island -> The island to deallocate.
- @result <- mach_error_t
-
- ***************************************************************************/
-
- static mach_error_t
-freeBranchIsland(
- BranchIsland *island )
-{
- assert( island );
- assert( (*(long*)&island->instructions[0]) == kIslandTemplate[0] );
- assert( island->allocatedHigh );
-
- mach_error_t err = err_none;
-
- if( island->allocatedHigh ) {
- vm_size_t pageSize;
- err = host_page_size( mach_host_self(), &pageSize );
- if( !err ) {
- assert( sizeof( BranchIsland ) <= pageSize );
- err = vm_deallocate(
- mach_task_self(),
- (vm_address_t) island, pageSize );
- }
- } else {
- free( island );
- }
-
- return err;
-}
-
-/***************************************************************************//**
- Implementation: Sets the branch island's target, with an optional
- instruction.
-
- @param island -> The branch island to insert target into.
- @param branchTo -> The address of the target.
- @param instruction -> Optional instruction to execute prior to branch. Set
- to zero for nop.
- @result <- mach_error_t
-
- ***************************************************************************/
-#if defined(__ppc__) || defined(__POWERPC__)
- static mach_error_t
-setBranchIslandTarget(
- BranchIsland *island,
- const void *branchTo,
- long instruction )
-{
- // Copy over the template code.
- bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
-
- // Fill in the address.
- ((short*)island->instructions)[kAddressLo] = ((long) branchTo) & 0x0000FFFF;
- ((short*)island->instructions)[kAddressHi]
- = (((long) branchTo) >> 16) & 0x0000FFFF;
-
- // Fill in the (optional) instuction.
- if( instruction != 0 ) {
- ((short*)island->instructions)[kInstructionLo]
- = instruction & 0x0000FFFF;
- ((short*)island->instructions)[kInstructionHi]
- = (instruction >> 16) & 0x0000FFFF;
- }
-
- //MakeDataExecutable( island->instructions, sizeof( kIslandTemplate ) );
- msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
-
- return err_none;
-}
-#endif
-
-#if defined(__i386__)
- static mach_error_t
-setBranchIslandTarget_i386(
- BranchIsland *island,
- const void *branchTo,
- char* instructions )
-{
-
- // Copy over the template code.
- bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
-
- // copy original instructions
- if (instructions) {
- bcopy (instructions, island->instructions + kInstructions, kOriginalInstructionsSize);
- }
-
- // Fill in the address.
- int32_t addressOffset = (char *)branchTo - (island->instructions + kJumpAddress + 4);
- *((int32_t *)(island->instructions + kJumpAddress)) = addressOffset;
-
- msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
- return err_none;
-}
-
-#elif defined(__x86_64__)
-static mach_error_t
-setBranchIslandTarget_i386(
- BranchIsland *island,
- const void *branchTo,
- char* instructions )
-{
- // Copy over the template code.
- bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
-
- // Copy original instructions.
- if (instructions) {
- bcopy (instructions, island->instructions, kOriginalInstructionsSize);
- }
-
- // Fill in the address.
- *((uint64_t *)(island->instructions + kJumpAddress)) = (uint64_t)branchTo;
- msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
-
- return err_none;
-}
-#endif
-
-
-#if defined(__i386__) || defined(__x86_64__)
-// simplistic instruction matching
-typedef struct {
- unsigned int length; // max 15
- unsigned char mask[15]; // sequence of bytes in memory order
- unsigned char constraint[15]; // sequence of bytes in memory order
-} AsmInstructionMatch;
-
-#if defined(__i386__)
-static AsmInstructionMatch possibleInstructions[] = {
- { 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE9, 0x00, 0x00, 0x00, 0x00} }, // jmp 0x????????
- { 0x5, {0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, {0x55, 0x89, 0xe5, 0xc9, 0xc3} }, // push %esp; mov %esp,%ebp; leave; ret
- { 0x1, {0xFF}, {0x90} }, // nop
- { 0x1, {0xF8}, {0x50} }, // push %reg
- { 0x2, {0xFF, 0xFF}, {0x89, 0xE5} }, // mov %esp,%ebp
- { 0x3, {0xFF, 0xFF, 0xFF}, {0x89, 0x1C, 0x24} }, // mov %ebx,(%esp)
- { 0x3, {0xFF, 0xFF, 0x00}, {0x83, 0xEC, 0x00} }, // sub 0x??, %esp
- { 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00}, {0x81, 0xEC, 0x00, 0x00, 0x00, 0x00} }, // sub 0x??, %esp with 32bit immediate
- { 0x2, {0xFF, 0xFF}, {0x31, 0xC0} }, // xor %eax, %eax
- { 0x3, {0xFF, 0x4F, 0x00}, {0x8B, 0x45, 0x00} }, // mov $imm(%ebp), %reg
- { 0x3, {0xFF, 0x4C, 0x00}, {0x8B, 0x40, 0x00} }, // mov $imm(%eax-%edx), %reg
- { 0x3, {0xFF, 0xCF, 0x00}, {0x8B, 0x4D, 0x00} }, // mov $imm(%rpb), %reg
- { 0x3, {0xFF, 0x4F, 0x00}, {0x8A, 0x4D, 0x00} }, // mov $imm(%ebp), %cl
- { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x8B, 0x4C, 0x24, 0x00} }, // mov $imm(%esp), %ecx
- { 0x4, {0xFF, 0x00, 0x00, 0x00}, {0x8B, 0x00, 0x00, 0x00} }, // mov r16,r/m16 or r32,r/m32
- { 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xB9, 0x00, 0x00, 0x00, 0x00} }, // mov $imm, %ecx
- { 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xB8, 0x00, 0x00, 0x00, 0x00} }, // mov $imm, %eax
- { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x66, 0x0F, 0xEF, 0x00} }, // pxor xmm2/128, xmm1
- { 0x2, {0xFF, 0xFF}, {0xDB, 0xE3} }, // fninit
- { 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE8, 0x00, 0x00, 0x00, 0x00} }, // call $imm
- { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x0F, 0xBE, 0x55, 0x00} }, // movsbl $imm(%ebp), %edx
- { 0x0, {0x00}, {0x00} }
-};
-#elif defined(__x86_64__)
-// TODO(glider): disassembling the "0x48, 0x89" sequences is trickier than it's done below.
-// If it stops working, refer to http://ref.x86asm.net/geek.html#modrm_byte_32_64 to do it
-// more accurately.
-// Note: 0x48 is in fact the REX.W prefix, but it might be wrong to treat it as a separate
-// instruction.
-static AsmInstructionMatch possibleInstructions[] = {
- { 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE9, 0x00, 0x00, 0x00, 0x00} }, // jmp 0x????????
- { 0x1, {0xFF}, {0x90} }, // nop
- { 0x1, {0xF8}, {0x50} }, // push %rX
- { 0x1, {0xFF}, {0x65} }, // GS prefix
- { 0x3, {0xFF, 0xFF, 0xFF}, {0x48, 0x89, 0xE5} }, // mov %rsp,%rbp
- { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x48, 0x83, 0xEC, 0x00} }, // sub 0x??, %rsp
- { 0x4, {0xFB, 0xFF, 0x07, 0x00}, {0x48, 0x89, 0x05, 0x00} }, // move onto rbp
- { 0x3, {0xFB, 0xFF, 0x00}, {0x48, 0x89, 0x00} }, // mov %reg, %reg
- { 0x3, {0xFB, 0xFF, 0x00}, {0x49, 0x89, 0x00} }, // mov %reg, %reg (REX.WB)
- { 0x2, {0xFF, 0x00}, {0x41, 0x00} }, // push %rXX
- { 0x2, {0xFF, 0x00}, {0x84, 0x00} }, // test %rX8,%rX8
- { 0x2, {0xFF, 0x00}, {0x85, 0x00} }, // test %rX,%rX
- { 0x2, {0xFF, 0x00}, {0x77, 0x00} }, // ja $i8
- { 0x2, {0xFF, 0x00}, {0x74, 0x00} }, // je $i8
- { 0x5, {0xF8, 0x00, 0x00, 0x00, 0x00}, {0xB8, 0x00, 0x00, 0x00, 0x00} }, // mov $imm, %reg
- { 0x3, {0xFF, 0xFF, 0x00}, {0xFF, 0x77, 0x00} }, // pushq $imm(%rdi)
- { 0x2, {0xFF, 0xFF}, {0x31, 0xC0} }, // xor %eax, %eax
- { 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0x25, 0x00, 0x00, 0x00, 0x00} }, // and $imm, %eax
- { 0x3, {0xFF, 0xFF, 0xFF}, {0x80, 0x3F, 0x00} }, // cmpb $imm, (%rdi)
-
- { 0x8, {0xFF, 0xFF, 0xCF, 0xFF, 0x00, 0x00, 0x00, 0x00},
- {0x48, 0x8B, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00}, }, // mov $imm, %{rax,rdx,rsp,rsi}
- { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x48, 0x83, 0xFA, 0x00}, }, // cmp $i8, %rdx
- { 0x4, {0xFF, 0xFF, 0x00, 0x00}, {0x83, 0x7f, 0x00, 0x00}, }, // cmpl $imm, $imm(%rdi)
- { 0xa, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
- {0x48, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00} }, // mov $imm, %rax
- { 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00},
- {0x81, 0xE6, 0x00, 0x00, 0x00, 0x00} }, // and $imm, %esi
- { 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00},
- {0xFF, 0x25, 0x00, 0x00, 0x00, 0x00} }, // jmpq *(%rip)
- { 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x66, 0x0F, 0xEF, 0x00} }, // pxor xmm2/128, xmm1
- { 0x2, {0xFF, 0x00}, {0x89, 0x00} }, // mov r/m32,r32 or r/m16,r16
- { 0x3, {0xFF, 0xFF, 0xFF}, {0x49, 0x89, 0xF8} }, // mov %rdi,%r8
- { 0x4, {0xFF, 0xFF, 0xFF, 0xFF}, {0x40, 0x0F, 0xBE, 0xCE} }, // movsbl %sil,%ecx
- { 0x7, {0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00},
- {0x48, 0x8D, 0x05, 0x00, 0x00, 0x00, 0x00} }, // lea $imm(%rip),%rax
- { 0x3, {0xFF, 0xFF, 0xFF}, {0x0F, 0xBE, 0xCE} }, // movsbl, %dh, %ecx
- { 0x3, {0xFF, 0xFF, 0x00}, {0xFF, 0x77, 0x00} }, // pushq $imm(%rdi)
- { 0x2, {0xFF, 0xFF}, {0xDB, 0xE3} }, // fninit
- { 0x3, {0xFF, 0xFF, 0xFF}, {0x48, 0x85, 0xD2} }, // test %rdx,%rdx
- { 0x0, {0x00}, {0x00} }
-};
-#endif
-
-static Boolean codeMatchesInstruction(unsigned char *code, AsmInstructionMatch* instruction)
-{
- Boolean match = true;
-
- size_t i;
- assert(instruction);
-#ifdef DEBUG_DISASM
- fprintf(stderr, "Matching: ");
-#endif
- for (i=0; i<instruction->length; i++) {
- unsigned char mask = instruction->mask[i];
- unsigned char constraint = instruction->constraint[i];
- unsigned char codeValue = code[i];
-#ifdef DEBUG_DISASM
- fprintf(stderr, "%x ", (unsigned)codeValue);
-#endif
- match = ((codeValue & mask) == constraint);
- if (!match) break;
- }
-#ifdef DEBUG_DISASM
- if (match) {
- fprintf(stderr, " OK\n");
- } else {
- fprintf(stderr, " FAIL\n");
- }
-#endif
- return match;
-}
-
-#if defined(__i386__) || defined(__x86_64__)
- static Boolean
-eatKnownInstructions(
- unsigned char *code,
- uint64_t *newInstruction,
- int *howManyEaten,
- char *originalInstructions,
- int *originalInstructionCount,
- uint8_t *originalInstructionSizes )
-{
- Boolean allInstructionsKnown = true;
- int totalEaten = 0;
- unsigned char* ptr = code;
- int remainsToEat = 5; // a JMP instruction takes 5 bytes
- int instructionIndex = 0;
-
- if (howManyEaten) *howManyEaten = 0;
- if (originalInstructionCount) *originalInstructionCount = 0;
- while (remainsToEat > 0) {
- Boolean curInstructionKnown = false;
-
- // See if instruction matches one we know
- AsmInstructionMatch* curInstr = possibleInstructions;
- do {
- if ((curInstructionKnown = codeMatchesInstruction(ptr, curInstr))) break;
- curInstr++;
- } while (curInstr->length > 0);
-
- // if all instruction matches failed, we don't know current instruction then, stop here
- if (!curInstructionKnown) {
- allInstructionsKnown = false;
- fprintf(stderr, "mach_override: some instructions unknown! Need to update mach_override.c\n");
- break;
- }
-
- // At this point, we've matched curInstr
- int eaten = curInstr->length;
- ptr += eaten;
- remainsToEat -= eaten;
- totalEaten += eaten;
-
- if (originalInstructionSizes) originalInstructionSizes[instructionIndex] = eaten;
- instructionIndex += 1;
- if (originalInstructionCount) *originalInstructionCount = instructionIndex;
- }
-
-
- if (howManyEaten) *howManyEaten = totalEaten;
-
- if (originalInstructions) {
- Boolean enoughSpaceForOriginalInstructions = (totalEaten < kOriginalInstructionsSize);
-
- if (enoughSpaceForOriginalInstructions) {
- memset(originalInstructions, 0x90 /* NOP */, kOriginalInstructionsSize); // fill instructions with NOP
- bcopy(code, originalInstructions, totalEaten);
- } else {
-#ifdef DEBUG_DISASM
- fprintf(stderr, "Not enough space in island to store original instructions. Adapt the island definition and kOriginalInstructionsSize\n");
-#endif
- return false;
- }
- }
-
- if (allInstructionsKnown) {
- // save last 3 bytes of first 64bits of codre we'll replace
- uint64_t currentFirst64BitsOfCode = *((uint64_t *)code);
- currentFirst64BitsOfCode = OSSwapInt64(currentFirst64BitsOfCode); // back to memory representation
- currentFirst64BitsOfCode &= 0x0000000000FFFFFFLL;
-
- // keep only last 3 instructions bytes, first 5 will be replaced by JMP instr
- *newInstruction &= 0xFFFFFFFFFF000000LL; // clear last 3 bytes
- *newInstruction |= (currentFirst64BitsOfCode & 0x0000000000FFFFFFLL); // set last 3 bytes
- }
-
- return allInstructionsKnown;
-}
-
- static void
-fixupInstructions(
- void *originalFunction,
- void *escapeIsland,
- void *instructionsToFix,
- int instructionCount,
- uint8_t *instructionSizes )
-{
- void *initialOriginalFunction = originalFunction;
- int index, fixed_size, code_size = 0;
- for (index = 0;index < instructionCount;index += 1)
- code_size += instructionSizes[index];
-
-#ifdef DEBUG_DISASM
- void *initialInstructionsToFix = instructionsToFix;
- fprintf(stderr, "BEFORE FIXING:\n");
- dump16Bytes(initialOriginalFunction);
- dump16Bytes(initialInstructionsToFix);
-#endif // DEBUG_DISASM
-
- for (index = 0;index < instructionCount;index += 1)
- {
- fixed_size = instructionSizes[index];
- if ((*(uint8_t*)instructionsToFix == 0xE9) || // 32-bit jump relative
- (*(uint8_t*)instructionsToFix == 0xE8)) // 32-bit call relative
- {
- uint32_t offset = (uintptr_t)originalFunction - (uintptr_t)escapeIsland;
- uint32_t *jumpOffsetPtr = (uint32_t*)((uintptr_t)instructionsToFix + 1);
- *jumpOffsetPtr += offset;
- }
- if ((*(uint8_t*)instructionsToFix == 0x74) || // Near jump if equal (je), 2 bytes.
- (*(uint8_t*)instructionsToFix == 0x77)) // Near jump if above (ja), 2 bytes.
- {
- // We replace a near je/ja instruction, "7P JJ", with a 32-bit je/ja, "0F 8P WW XX YY ZZ".
- // This is critical, otherwise a near jump will likely fall outside the original function.
- uint32_t offset = (uintptr_t)initialOriginalFunction - (uintptr_t)escapeIsland;
- uint32_t jumpOffset = *(uint8_t*)((uintptr_t)instructionsToFix + 1);
- *((uint8_t*)instructionsToFix + 1) = *(uint8_t*)instructionsToFix + 0x10;
- *(uint8_t*)instructionsToFix = 0x0F;
- uint32_t *jumpOffsetPtr = (uint32_t*)((uintptr_t)instructionsToFix + 2 );
- *jumpOffsetPtr = offset + jumpOffset;
- fixed_size = 6;
- }
-
- originalFunction = (void*)((uintptr_t)originalFunction + instructionSizes[index]);
- escapeIsland = (void*)((uintptr_t)escapeIsland + instructionSizes[index]);
- instructionsToFix = (void*)((uintptr_t)instructionsToFix + fixed_size);
-
- // Expanding short instructions into longer ones may overwrite the next instructions,
- // so we must restore them.
- code_size -= fixed_size;
- if ((code_size > 0) && (fixed_size != instructionSizes[index])) {
- bcopy(originalFunction, instructionsToFix, code_size);
- }
- }
-#ifdef DEBUG_DISASM
- fprintf(stderr, "AFTER_FIXING:\n");
- dump16Bytes(initialOriginalFunction);
- dump16Bytes(initialInstructionsToFix);
-#endif // DEBUG_DISASM
-}
-
-#ifdef DEBUG_DISASM
-#define HEX_DIGIT(x) ((((x) % 16) < 10) ? ('0' + ((x) % 16)) : ('A' + ((x) % 16 - 10)))
-
- static void
-dump16Bytes(
- void *ptr) {
- int i;
- char buf[3];
- uint8_t *bytes = (uint8_t*)ptr;
- for (i = 0; i < 16; i++) {
- buf[0] = HEX_DIGIT(bytes[i] / 16);
- buf[1] = HEX_DIGIT(bytes[i] % 16);
- buf[2] = ' ';
- write(2, buf, 3);
- }
- write(2, "\n", 1);
-}
-#endif // DEBUG_DISASM
-#endif
-
-#if defined(__i386__)
-__asm(
- ".text;"
- ".align 2, 0x90;"
- "_atomic_mov64:;"
- " pushl %ebp;"
- " movl %esp, %ebp;"
- " pushl %esi;"
- " pushl %ebx;"
- " pushl %ecx;"
- " pushl %eax;"
- " pushl %edx;"
-
- // atomic push of value to an address
- // we use cmpxchg8b, which compares content of an address with
- // edx:eax. If they are equal, it atomically puts 64bit value
- // ecx:ebx in address.
- // We thus put contents of address in edx:eax to force ecx:ebx
- // in address
- " mov 8(%ebp), %esi;" // esi contains target address
- " mov 12(%ebp), %ebx;"
- " mov 16(%ebp), %ecx;" // ecx:ebx now contains value to put in target address
- " mov (%esi), %eax;"
- " mov 4(%esi), %edx;" // edx:eax now contains value currently contained in target address
- " lock; cmpxchg8b (%esi);" // atomic move.
-
- // restore registers
- " popl %edx;"
- " popl %eax;"
- " popl %ecx;"
- " popl %ebx;"
- " popl %esi;"
- " popl %ebp;"
- " ret"
-);
-#elif defined(__x86_64__)
-void atomic_mov64(
- uint64_t *targetAddress,
- uint64_t value )
-{
- *targetAddress = value;
-}
-#endif
-#endif
-#endif // __APPLE__
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