[23545] trunk/dports/lang/erlang
source_changes at macosforge.org
source_changes at macosforge.org
Tue Apr 3 23:36:22 PDT 2007
Revision: 23545
http://trac.macosforge.org/projects/macports/changeset/23545
Author: bfulgham at macports.org
Date: 2007-04-03 23:36:21 -0700 (Tue, 03 Apr 2007)
Log Message:
-----------
Update to support HiPE for x86.
Modified Paths:
--------------
trunk/dports/lang/erlang/Portfile
Added Paths:
-----------
trunk/dports/lang/erlang/files/mach_override.c
trunk/dports/lang/erlang/files/mach_override.h
Modified: trunk/dports/lang/erlang/Portfile
===================================================================
--- trunk/dports/lang/erlang/Portfile 2007-04-04 04:22:26 UTC (rev 23544)
+++ trunk/dports/lang/erlang/Portfile 2007-04-04 06:36:21 UTC (rev 23545)
@@ -3,7 +3,7 @@
PortSystem 1.0
name erlang
version R11B-4
-revision 1
+revision 2
categories lang erlang
maintainers bfulgham at macports.org
platforms darwin
@@ -51,6 +51,15 @@
configure.args-delete --disable-smp-support
}
+platform i386 {
+ pre-configure {
+ file copy ${filespath}/mach_override.[ch] ${workpath}/${name}-${version}/erts/emulator/hipe
+ configure.args-append --enable-hipe
+ }
+}
+
+
+
depends_build bin:gawk:gawk
depends_run bin:wish:tk
Added: trunk/dports/lang/erlang/files/mach_override.c
===================================================================
--- trunk/dports/lang/erlang/files/mach_override.c (rev 0)
+++ trunk/dports/lang/erlang/files/mach_override.c 2007-04-04 06:36:21 UTC (rev 23545)
@@ -0,0 +1,603 @@
+/*******************************************************************************
+ mach_override.c
+ Copyright (c) 2003-2005 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+ Some rights reserved: <http://creativecommons.org/licenses/by/2.0/>
+
+ ***************************************************************************/
+
+#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>
+
+/**************************
+*
+* Constants
+*
+**************************/
+#pragma mark -
+#pragma mark (Constants)
+
+#if defined(__ppc__) || defined(__POWERPC__)
+
+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
+
+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
+#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)
+
+ mach_error_t
+allocateBranchIsland(
+ BranchIsland **island,
+ int allocateHigh );
+
+ mach_error_t
+freeBranchIsland(
+ BranchIsland *island );
+
+#if defined(__ppc__) || defined(__POWERPC__)
+ mach_error_t
+setBranchIslandTarget(
+ BranchIsland *island,
+ const void *branchTo,
+ long instruction );
+#endif
+
+#if defined(__i386__)
+mach_error_t
+setBranchIslandTarget_i386(
+ BranchIsland *island,
+ const void *branchTo,
+ char* instructions );
+void
+atomic_mov64(
+ uint64_t *targetAddress,
+ uint64_t value );
+
+ static Boolean
+eatKnownInstructions(
+ unsigned char *code,
+ uint64_t *newInstruction,
+ int *howManyEaten,
+ char *originalInstructions );
+#endif
+
+/*******************************************************************************
+*
+* Interface
+*
+*******************************************************************************/
+#pragma mark -
+#pragma mark (Interface)
+
+ mach_error_t
+mach_override(
+ char *originalFunctionSymbolName,
+ const char *originalFunctionLibraryNameHint,
+ const void *overrideFunctionAddress,
+ void **originalFunctionReentryIsland )
+{
+ assert( originalFunctionSymbolName );
+ assert( strlen( originalFunctionSymbolName ) );
+ assert( overrideFunctionAddress );
+
+ // Lookup the original function's code pointer.
+ long *originalFunctionPtr;
+ if( originalFunctionLibraryNameHint )
+ _dyld_lookup_and_bind_with_hint(
+ originalFunctionSymbolName,
+ originalFunctionLibraryNameHint,
+ (void*) &originalFunctionPtr,
+ NULL );
+ else
+ _dyld_lookup_and_bind(
+ originalFunctionSymbolName,
+ (void*) &originalFunctionPtr,
+ NULL );
+
+ return mach_override_ptr( originalFunctionPtr, overrideFunctionAddress,
+ originalFunctionReentryIsland );
+}
+
+ mach_error_t
+mach_override_ptr(
+ void *originalFunctionAddress,
+ const void *overrideFunctionAddress,
+ void **originalFunctionReentryIsland )
+{
+ assert( originalFunctionAddress );
+ assert( overrideFunctionAddress );
+
+ 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__)
+ int eatenCount = 0;
+ char originalInstructions[kOriginalInstructionsSize];
+ uint64_t jumpRelativeInstruction = 0; // JMP
+
+ Boolean overridePossible = eatKnownInstructions ((unsigned char *)originalFunctionPtr,
+ &jumpRelativeInstruction, &eatenCount, originalInstructions);
+ if (eatenCount > kOriginalInstructionsSize) {
+ //printf ("Too many instructions eaten\n");
+ overridePossible = false;
+ }
+ if (!overridePossible) err = err_cannot_override;
+#endif
+
+ // Make the original function implementation writable.
+ if( !err ) {
+ err = vm_protect( mach_task_self(),
+ (vm_address_t) originalFunctionPtr,
+ sizeof(long), false, (VM_PROT_ALL | VM_PROT_COPY) );
+ if( err )
+ err = vm_protect( mach_task_self(),
+ (vm_address_t) originalFunctionPtr, sizeof(long), false,
+ (VM_PROT_DEFAULT | VM_PROT_COPY) );
+ }
+
+ // Allocate and target the escape island to the overriding function.
+ BranchIsland *escapeIsland = NULL;
+ if( !err )
+ err = allocateBranchIsland( &escapeIsland, kAllocateHigh );
+
+#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__)
+ if( !err )
+ err = setBranchIslandTarget_i386( escapeIsland, overrideFunctionAddress, 0 );
+
+ // Build the jump relative instruction to the escape island
+ if (!err) {
+ int32_t addressOffset = ((int32_t)escapeIsland - (int32_t)originalFunctionPtr - 5);
+ addressOffset = OSSwapInt32(addressOffset);
+
+ jumpRelativeInstruction |= 0xE900000000000000LL;
+ jumpRelativeInstruction |= ((uint64_t)addressOffset & 0xffffffff) << 24;
+ jumpRelativeInstruction = OSSwapInt64(jumpRelativeInstruction);
+ }
+#endif
+
+ // Optionally allocate & return the reentry island.
+ BranchIsland *reentryIsland = NULL;
+ if( !err && originalFunctionReentryIsland ) {
+ err = allocateBranchIsland( &reentryIsland, kAllocateNormal );
+ 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__)
+ // 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 ) {
+ if( reentryIsland )
+ err = setBranchIslandTarget_i386( reentryIsland,
+ (void*) ((char *)originalFunctionPtr+eatenCount), originalInstructions );
+ if ( !err )
+ atomic_mov64((uint64_t *)originalFunctionPtr, jumpRelativeInstruction);
+ }
+#endif
+
+ // Clean up on error.
+ if( err ) {
+ if( reentryIsland )
+ freeBranchIsland( reentryIsland );
+ if( escapeIsland )
+ freeBranchIsland( escapeIsland );
+ }
+
+ 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
+
+ ***************************************************************************/
+
+ mach_error_t
+allocateBranchIsland(
+ BranchIsland **island,
+ int allocateHigh )
+{
+ 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 );
+ vm_address_t first = 0xfeffffff;
+ vm_address_t last = 0xfe000000 + pageSize;
+ 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 ) {
+ page += pageSize;
+ err = err_none;
+ }
+ }
+ if( allocated )
+ *island = (void*) 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
+
+ ***************************************************************************/
+
+ 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__)
+ 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__)
+ 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;
+
+ //MakeDataExecutable( island->instructions, sizeof( kIslandTemplate ) );
+ msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+
+ return err_none;
+}
+#endif
+
+
+#if defined (__i386__)
+// 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;
+
+static AsmInstructionMatch possibleInstructions[] = {
+ { 0x1, {0xFF}, {0x90} }, // nop
+ { 0x1, {0xFF}, {0x55} }, // push %esp
+ { 0x2, {0xFF, 0xFF}, {0x89, 0xE5} }, // mov %esp,%ebp
+ { 0x1, {0xFF}, {0x53} }, // push %ebx
+ { 0x3, {0xFF, 0xFF, 0x00}, {0x83, 0xEC, 0x00} }, // sub 0x??, %esp
+ { 0x1, {0xFF}, {0x57} }, // push %edi
+ { 0x1, {0xFF}, {0x56} }, // push %esi
+ { 0x0 }
+};
+
+static Boolean codeMatchesInstruction(unsigned char *code, AsmInstructionMatch* instruction)
+{
+ Boolean match = true;
+
+ int i;
+ for (i=0; i<instruction->length; i++) {
+ unsigned char mask = instruction->mask[i];
+ unsigned char constraint = instruction->constraint[i];
+ unsigned char codeValue = code[i];
+ match = ((codeValue & mask) == constraint);
+ if (!match) break;
+ }
+
+ return match;
+}
+
+ static Boolean
+eatKnownInstructions(
+ unsigned char *code,
+ uint64_t* newInstruction,
+ int* howManyEaten,
+ char* originalInstructions )
+{
+ Boolean allInstructionsKnown = true;
+ int totalEaten = 0;
+ unsigned char* ptr = code;
+ int remainsToEat = 5; // a JMP instruction takes 5 bytes
+
+ if (howManyEaten) *howManyEaten = 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;
+ break;
+ }
+
+ // At this point, we've matched curInstr
+ int eaten = curInstr->length;
+ ptr += eaten;
+ remainsToEat -= eaten;
+ totalEaten += eaten;
+ }
+
+
+ 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 {
+ // printf ("Not enough space in island to store original instructions. Adapt the island definition and kOriginalInstructionsSize\n");
+ 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;
+}
+
+asm(
+ ".text;"
+ ".align 2, 0x90;"
+ ".globl _atomic_mov64;"
+ "_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"
+);
+
+#endif
Added: trunk/dports/lang/erlang/files/mach_override.h
===================================================================
--- trunk/dports/lang/erlang/files/mach_override.h (rev 0)
+++ trunk/dports/lang/erlang/files/mach_override.h 2007-04-04 06:36:21 UTC (rev 23545)
@@ -0,0 +1,123 @@
+/*******************************************************************************
+ mach_override.h
+ Copyright (c) 2003-2005 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+ Some rights reserved: <http://creativecommons.org/licenses/by/2.0/>
+
+ ***************************************************************************/
+
+/***************************************************************************//**
+ @mainpage mach_override
+ @author Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+
+ This package, coded in C to the Mach API, allows you to override ("patch")
+ program- and system-supplied functions at runtime. You can fully replace
+ functions with your implementations, or merely head- or tail-patch the
+ original implementations.
+
+ Use it by #include'ing mach_override.h from your .c, .m or .mm file(s).
+
+ @todo Discontinue use of Carbon's MakeDataExecutable() and
+ CompareAndSwap() calls and start using the Mach equivalents, if they
+ exist. If they don't, write them and roll them in. That way, this
+ code will be pure Mach, which will make it easier to use everywhere.
+ Update: MakeDataExecutable() has been replaced by
+ msync(MS_INVALIDATE). There is an OSCompareAndSwap in libkern, but
+ I'm currently unsure if I can link against it. May have to roll in
+ my own version...
+ @todo Stop using an entire 4K high-allocated VM page per 28-byte escape
+ branch island. Done right, this will dramatically speed up escape
+ island allocations when they number over 250. Then again, if you're
+ overriding more than 250 functions, maybe speed isn't your main
+ concern...
+ @todo Add detection of: b, bl, bla, bc, bcl, bcla, bcctrl, bclrl
+ first-instructions. Initially, we should refuse to override
+ functions beginning with these instructions. Eventually, we should
+ dynamically rewrite them to make them position-independent.
+ @todo Write mach_unoverride(), which would remove an override placed on a
+ function. Must be multiple-override aware, which means an almost
+ complete rewrite under the covers, because the target address can't
+ be spread across two load instructions like it is now since it will
+ need to be atomically updatable.
+ @todo Add non-rentry variants of overrides to test_mach_override.
+
+ ***************************************************************************/
+
+#ifndef _mach_override_
+#define _mach_override_
+
+#include <sys/types.h>
+#include <mach/error.h>
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/**
+ Returned if the function to be overrided begins with a 'mfctr' instruction.
+*/
+#define err_cannot_override (err_local|1)
+
+/***************************************************************************//**
+ Dynamically overrides the function implementation referenced by
+ originalFunctionSymbolName with the implentation pointed to by
+ overrideFunctionAddress. Optionally returns a pointer to a "reentry island"
+ which, if jumped to, will resume the original implementation.
+
+ @param originalFunctionSymbolName -> Required symbol name of the
+ function to override (with
+ overrideFunctionAddress).
+ Remember, C function name
+ symbols are prepended with an
+ underscore.
+ @param originalFunctionLibraryNameHint -> Optional name of the library
+ which contains
+ originalFunctionSymbolName. Can
+ be NULL, but this may result in
+ the wrong function being
+ overridden and/or a crash.
+ @param overrideFunctionAddress -> Required address to the
+ overriding function.
+ @param originalFunctionReentryIsland <- Optional pointer to pointer to
+ the reentry island. Can be NULL.
+ @result <- err_cannot_override if the
+ original function's
+ implementation begins with the
+ 'mfctr' instruction.
+
+ ***************************************************************************/
+
+ mach_error_t
+mach_override(
+ char *originalFunctionSymbolName,
+ const char *originalFunctionLibraryNameHint,
+ const void *overrideFunctionAddress,
+ void **originalFunctionReentryIsland );
+
+/************************************************************************************//**
+ Dynamically overrides the function implementation referenced by
+ originalFunctionAddress with the implentation pointed to by overrideFunctionAddress.
+ Optionally returns a pointer to a "reentry island" which, if jumped to, will resume
+ the original implementation.
+
+ @param originalFunctionAddress -> Required address of the function to
+ override (with overrideFunctionAddress).
+ @param overrideFunctionAddress -> Required address to the overriding
+ function.
+ @param originalFunctionReentryIsland <- Optional pointer to pointer to the
+ reentry island. Can be NULL.
+ @result <- err_cannot_override if the original
+ function's implementation begins with
+ the 'mfctr' instruction.
+
+ ************************************************************************************/
+
+ mach_error_t
+mach_override_ptr(
+ void *originalFunctionAddress,
+ const void *overrideFunctionAddress,
+ void **originalFunctionReentryIsland );
+
+#ifdef __cplusplus
+ }
+#endif
+#endif // _mach_override_
\ No newline at end of file
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