--- /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__
projects / thirdparty / gcc.git / commitdiff
