Revert 126020 - Experiment for updating the tcmalloc chromium branch to r144 (gperftools 2.0).

third_party/tcmalloc/chromium/src/windows/preamble_patcher.cc

 /* Copyright (c) 2007, Google Inc.
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  * 
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 11 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * ---
  * Author: Joi Sigurdsson
- * Author: Scott Francis
  *
  * Implementation of PreamblePatcher
  */
 
 #include "preamble_patcher.h"
 
 #include "mini_disassembler.h"
 
 // compatibility shims
 #include "base/logging.h"
 
 // Definitions of assembly statements we need
 #define ASM_JMP32REL 0xE9
 #define ASM_INT3 0xCC
 #define ASM_JMP32ABS_0 0xFF
 #define ASM_JMP32ABS_1 0x25
 #define ASM_JMP8REL 0xEB
-#define ASM_JCC32REL_0 0x0F
-#define ASM_JCC32REL_1_MASK 0x80
-#define ASM_NOP 0x90
-// X64 opcodes
-#define ASM_REXW 0x48
-#define ASM_MOVRAX_IMM 0xB8
-#define ASM_JMP 0xFF
-#define ASM_JMP_RAX 0xE0
 
 namespace sidestep {
 
-PreamblePatcher::PreamblePage* PreamblePatcher::preamble_pages_ = NULL;
-long PreamblePatcher::granularity_ = 0;
-long PreamblePatcher::pagesize_ = 0;
-bool PreamblePatcher::initialized_ = false;
-
-static const unsigned int kPreamblePageMagic = 0x4347414D; // "MAGC"
-
 // Handle a special case that we see with functions that point into an
 // IAT table (including functions linked statically into the
 // application): these function already starts with ASM_JMP32*.  For
 // instance, malloc() might be implemented as a JMP to __malloc().
 // This function follows the initial JMPs for us, until we get to the
 // place where the actual code is defined.  If we get to STOP_BEFORE,
-// we return the address before stop_before.  The stop_before_trampoline
-// flag is used in 64-bit mode.  If true, we will return the address
-// before a trampoline is detected.  Trampolines are defined as:
-//
-//    nop
-//    mov rax, <replacement_function>
-//    jmp rax
-//
-// See PreamblePatcher::RawPatchWithStub for more information.
+// we return the address before stop_before.
 void* PreamblePatcher::ResolveTargetImpl(unsigned char* target,
-                                         unsigned char* stop_before,
-                                         bool stop_before_trampoline) {
+                                         unsigned char* stop_before) {
   if (target == NULL)
     return NULL;
   while (1) {
     unsigned char* new_target;
     if (target[0] == ASM_JMP32REL) {
       // target[1-4] holds the place the jmp goes to, but it's
       // relative to the next instruction.
       int relative_offset;   // Windows guarantees int is 4 bytes
       SIDESTEP_ASSERT(sizeof(relative_offset) == 4);
       memcpy(reinterpret_cast<void*>(&relative_offset),
              reinterpret_cast<void*>(target + 1), 4);
       new_target = target + 5 + relative_offset;
     } else if (target[0] == ASM_JMP8REL) {
       // Visual Studio 7.1 implements new[] as an 8 bit jump to new
       signed char relative_offset;
       memcpy(reinterpret_cast<void*>(&relative_offset),
              reinterpret_cast<void*>(target + 1), 1);
       new_target = target + 2 + relative_offset;
     } else if (target[0] == ASM_JMP32ABS_0 &&
                target[1] == ASM_JMP32ABS_1) {
       // Visual studio seems to sometimes do it this way instead of the
       // previous way.  Not sure what the rules are, but it was happening
       // with operator new in some binaries.
-      void** new_target_v;
-      if (kIs64BitBinary) {
-        // In 64-bit mode JMPs are RIP-relative, not absolute
-        int target_offset;
-        memcpy(reinterpret_cast<void*>(&target_offset),
-               reinterpret_cast<void*>(target + 2), 4);
-        new_target_v = reinterpret_cast<void**>(target + target_offset + 6);
-      } else {
-        SIDESTEP_ASSERT(sizeof(new_target) == 4);
-        memcpy(&new_target_v, reinterpret_cast<void*>(target + 2), 4);
-      }
+      void **new_target_v;
+      SIDESTEP_ASSERT(sizeof(new_target) == 4);
+      memcpy(&new_target_v, reinterpret_cast<void*>(target + 2), 4);
       new_target = reinterpret_cast<unsigned char*>(*new_target_v);
     } else {
       break;
     }
     if (new_target == stop_before)
       break;
-    if (stop_before_trampoline && *new_target == ASM_NOP
-        && new_target[1] == ASM_REXW && new_target[2] == ASM_MOVRAX_IMM)
-      break;
     target = new_target;
   }
   return target;
 }
 
 // Special case scoped_ptr to avoid dependency on scoped_ptr below.
 class DeleteUnsignedCharArray {
  public:
   DeleteUnsignedCharArray(unsigned char* array) : array_(array) {
   }
 
   ~DeleteUnsignedCharArray() {
     if (array_) {
-      PreamblePatcher::FreePreambleBlock(array_);
+      delete [] array_;
     }
   }
 
   unsigned char* Release() {
     unsigned char* temp = array_;
     array_ = NULL;
     return temp;
   }
 
  private:
@@ skipping 67 matching lines @@
 
 SideStepError PreamblePatcher::RawPatch(void* target_function,
                                         void* replacement_function,
                                         void** original_function_stub) {
   if (!target_function || !replacement_function || !original_function_stub ||
       (*original_function_stub) || target_function == replacement_function) {
     SIDESTEP_ASSERT(false && "Preconditions not met");
     return SIDESTEP_INVALID_PARAMETER;
   }
 
-  BOOL succeeded = FALSE;
-
-  // First, deal with a special case that we see with functions that
-  // point into an IAT table (including functions linked statically
-  // into the application): these function already starts with
-  // ASM_JMP32REL.  For instance, malloc() might be implemented as a
-  // JMP to __malloc().  In that case, we replace the destination of
-  // the JMP (__malloc), rather than the JMP itself (malloc).  This
-  // way we get the correct behavior no matter how malloc gets called.
-  void* new_target = ResolveTarget(target_function);
-  if (new_target != target_function) {
-    target_function = new_target;
-  }
-
-  // In 64-bit mode, preamble_stub must be within 2GB of target function
-  // so that if target contains a jump, we can translate it.
-  unsigned char* preamble_stub = AllocPreambleBlockNear(target_function);
+  // @see MAX_PREAMBLE_STUB_SIZE for an explanation of how we arrives at
+  // this size
+  unsigned char* preamble_stub = new unsigned char[MAX_PREAMBLE_STUB_SIZE];
   if (!preamble_stub) {
     SIDESTEP_ASSERT(false && "Unable to allocate preamble-stub.");
     return SIDESTEP_INSUFFICIENT_BUFFER;
   }
 
   // Frees the array at end of scope.
   DeleteUnsignedCharArray guard_preamble_stub(preamble_stub);
 
+  // Change the protection of the newly allocated preamble stub to
+  // PAGE_EXECUTE_READWRITE. This is required to work with DEP (Data
+  // Execution Prevention) which will cause an exception if code is executed
+  // from a page on which you do not have read access.
+  DWORD old_stub_protect = 0;
+  BOOL succeeded = ::VirtualProtect(preamble_stub, MAX_PREAMBLE_STUB_SIZE,
+                                    PAGE_EXECUTE_READWRITE, &old_stub_protect);
+  if (!succeeded) {
+    SIDESTEP_ASSERT(false &&
+                    "Failed to make page preamble stub read-write-execute.");
+    return SIDESTEP_ACCESS_DENIED;
+  }
+
   SideStepError error_code = RawPatchWithStubAndProtections(
       target_function, replacement_function, preamble_stub,
       MAX_PREAMBLE_STUB_SIZE, NULL);
 
   if (SIDESTEP_SUCCESS != error_code) {
     SIDESTEP_ASSERT(false);
     return error_code;
   }
 
   // Flush the instruction cache to make sure the processor doesn't execute the
@@ skipping 25 matching lines @@
 SideStepError PreamblePatcher::Unpatch(void* target_function,
                                        void* replacement_function,
                                        void* original_function_stub) {
   SIDESTEP_ASSERT(target_function && replacement_function &&
                   original_function_stub);
   if (!target_function || !replacement_function ||
       !original_function_stub) {
     return SIDESTEP_INVALID_PARAMETER;
   }
 
+  // We disassemble the preamble of the _stub_ to see how many bytes we
+  // originally copied to the stub.
+  MiniDisassembler disassembler;
+  unsigned int preamble_bytes = 0;
+  while (preamble_bytes < 5) {
+    InstructionType instruction_type =
+        disassembler.Disassemble(
+            reinterpret_cast<unsigned char*>(original_function_stub) +
+            preamble_bytes,
+            preamble_bytes);
+    if (IT_GENERIC != instruction_type) {
+      SIDESTEP_ASSERT(false &&
+                      "Should only have generic instructions in stub!!");
+      return SIDESTEP_UNSUPPORTED_INSTRUCTION;
+    }
+  }
+
   // Before unpatching, target_function should be a JMP to
   // replacement_function.  If it's not, then either it's an error, or
   // we're falling into the case where the original instruction was a
   // JMP, and we patched the jumped_to address rather than the JMP
   // itself.  (For instance, if malloc() is just a JMP to __malloc(),
   // we patched __malloc() and not malloc().)
   unsigned char* target = reinterpret_cast<unsigned char*>(target_function);
   target = reinterpret_cast<unsigned char*>(
       ResolveTargetImpl(
-          target, reinterpret_cast<unsigned char*>(replacement_function),
-          true));
+          target, reinterpret_cast<unsigned char*>(replacement_function)));
   // We should end at the function we patched.  When we patch, we insert
   // a ASM_JMP32REL instruction, so look for that as a sanity check.
   if (target[0] != ASM_JMP32REL) {
     SIDESTEP_ASSERT(false &&
                     "target_function does not look like it was patched.");
     return SIDESTEP_INVALID_PARAMETER;
   }
 
-  const unsigned int kRequiredTargetPatchBytes = 5;
-
   // We need to be able to write to a process-local copy of the first
-  // kRequiredTargetPatchBytes bytes of target_function
+  // MAX_PREAMBLE_STUB_SIZE bytes of target_function
   DWORD old_target_function_protect = 0;
-  BOOL succeeded = ::VirtualProtect(reinterpret_cast<void*>(target),
-                                    kRequiredTargetPatchBytes,
+  BOOL succeeded = ::VirtualProtect(reinterpret_cast<void*>(target_function),
+                                    MAX_PREAMBLE_STUB_SIZE,
                                     PAGE_EXECUTE_READWRITE,
                                     &old_target_function_protect);
   if (!succeeded) {
     SIDESTEP_ASSERT(false && "Failed to make page containing target function "
                     "copy-on-write.");
     return SIDESTEP_ACCESS_DENIED;
   }
 
-  unsigned char* preamble_stub = reinterpret_cast<unsigned char*>(
-                                   original_function_stub);
+  // Replace the first few bytes of the original function with the bytes we
+  // previously moved to the preamble stub.
+  memcpy(reinterpret_cast<void*>(target),
+         original_function_stub, preamble_bytes);
 
-  // Disassemble the preamble of stub and copy the bytes back to target.
-  // If we've done any conditional jumps in the preamble we need to convert
-  // them back to the orignal REL8 jumps in the target.
-  MiniDisassembler disassembler;
-  unsigned int preamble_bytes = 0;
-  unsigned int target_bytes = 0;
-  while (target_bytes < kRequiredTargetPatchBytes) {
-    unsigned int cur_bytes = 0;
-    InstructionType instruction_type =
-        disassembler.Disassemble(preamble_stub + preamble_bytes, cur_bytes);
-    if (IT_JUMP == instruction_type) {
-      unsigned int jump_bytes = 0;
-      SideStepError jump_ret = SIDESTEP_JUMP_INSTRUCTION;
-      if (IsNearConditionalJump(preamble_stub + preamble_bytes, cur_bytes) ||
-          IsNearRelativeJump(preamble_stub + preamble_bytes, cur_bytes) ||
-          IsNearAbsoluteCall(preamble_stub + preamble_bytes, cur_bytes) ||
-          IsNearRelativeCall(preamble_stub + preamble_bytes, cur_bytes)) {
-        jump_ret = PatchNearJumpOrCall(preamble_stub + preamble_bytes, 
-                                       cur_bytes, target + target_bytes, 
-                                       &jump_bytes, MAX_PREAMBLE_STUB_SIZE);
-      }
-      if (jump_ret == SIDESTEP_JUMP_INSTRUCTION) {
-        SIDESTEP_ASSERT(false &&
-                        "Found unsupported jump instruction in stub!!");
-        return SIDESTEP_UNSUPPORTED_INSTRUCTION;
-      }
-      target_bytes += jump_bytes;
-    } else if (IT_GENERIC == instruction_type) {
-      if (IsMovWithDisplacement(preamble_stub + preamble_bytes, cur_bytes)) {
-        unsigned int mov_bytes = 0;
-        if (PatchMovWithDisplacement(preamble_stub + preamble_bytes, cur_bytes,
-                                     target + target_bytes, &mov_bytes,
-                                     MAX_PREAMBLE_STUB_SIZE)
-                                     != SIDESTEP_SUCCESS) {
-          SIDESTEP_ASSERT(false &&
-                          "Found unsupported generic instruction in stub!!");
-          return SIDESTEP_UNSUPPORTED_INSTRUCTION;
-        }
-      } else {
-        memcpy(reinterpret_cast<void*>(target + target_bytes),
-               reinterpret_cast<void*>(reinterpret_cast<unsigned char*>(
-                   original_function_stub) + preamble_bytes), cur_bytes);
-        target_bytes += cur_bytes;
-      }
-    } else {
-      SIDESTEP_ASSERT(false &&
-                      "Found unsupported instruction in stub!!");
-      return SIDESTEP_UNSUPPORTED_INSTRUCTION;
-    }
-    preamble_bytes += cur_bytes;
-  }
+  // Stub is now useless so delete it.
+  // [csilvers: Commented out for perftools because it causes big problems
+  //  when we're unpatching malloc.  We just let this live on as a  leak.]
+  //delete [] reinterpret_cast<unsigned char*>(original_function_stub);
 
-  FreePreambleBlock(reinterpret_cast<unsigned char*>(original_function_stub));
-
-  // Restore the protection of the first kRequiredTargetPatchBytes bytes of
+  // Restore the protection of the first MAX_PREAMBLE_STUB_SIZE bytes of
   // target to what they were before we started goofing around.
   succeeded = ::VirtualProtect(reinterpret_cast<void*>(target),
-                               kRequiredTargetPatchBytes,
+                               MAX_PREAMBLE_STUB_SIZE,
                                old_target_function_protect,
                                &old_target_function_protect);
 
   // Flush the instruction cache to make sure the processor doesn't execute the
   // old version of the instructions (before our patch).
   //
   // See comment on FlushInstructionCache elsewhere in this file.
   succeeded = ::FlushInstructionCache(::GetCurrentProcess(),
                                       target,
                                       MAX_PREAMBLE_STUB_SIZE);
   if (!succeeded) {
     SIDESTEP_ASSERT(false && "Failed to flush instruction cache.");
     return SIDESTEP_UNEXPECTED;
   }
 
   SIDESTEP_LOG("PreamblePatcher::Unpatch successfully unpatched.");
   return SIDESTEP_SUCCESS;
 }
 
-void PreamblePatcher::Initialize() {
-  if (!initialized_) {
-    SYSTEM_INFO si = { 0 };
-    ::GetSystemInfo(&si);
-    granularity_ = si.dwAllocationGranularity;
-    pagesize_ = si.dwPageSize;
-    initialized_ = true;
-  }
-}
-
-unsigned char* PreamblePatcher::AllocPreambleBlockNear(void* target) {
-  PreamblePage* preamble_page = preamble_pages_;
-  while (preamble_page != NULL) {
-    if (preamble_page->free_ != NULL) {
-      __int64 val = reinterpret_cast<__int64>(preamble_page) -
-          reinterpret_cast<__int64>(target);
-      if ((val > 0 && val + pagesize_ <= INT_MAX) ||
-          (val < 0 && val >= INT_MIN)) {
-        break;
-      }
-    }
-    preamble_page = preamble_page->next_;
-  }
-
-  // The free_ member of the page is used to store the next available block
-  // of memory to use or NULL if there are no chunks available, in which case
-  // we'll allocate a new page.
-  if (preamble_page == NULL || preamble_page->free_ == NULL) {
-    // Create a new preamble page and initialize the free list
-    preamble_page = reinterpret_cast<PreamblePage*>(AllocPageNear(target));
-    SIDESTEP_ASSERT(preamble_page != NULL && "Could not allocate page!");
-    void** pp = &preamble_page->free_;
-    unsigned char* ptr = reinterpret_cast<unsigned char*>(preamble_page) +
-        MAX_PREAMBLE_STUB_SIZE;
-    unsigned char* limit = reinterpret_cast<unsigned char*>(preamble_page) +
-        pagesize_;
-    while (ptr < limit) {
-      *pp = ptr;
-      pp = reinterpret_cast<void**>(ptr);
-      ptr += MAX_PREAMBLE_STUB_SIZE;
-    }
-    *pp = NULL;
-    // Insert the new page into the list
-    preamble_page->magic_ = kPreamblePageMagic;
-    preamble_page->next_ = preamble_pages_;
-    preamble_pages_ = preamble_page;
-  }
-  unsigned char* ret = reinterpret_cast<unsigned char*>(preamble_page->free_);
-  preamble_page->free_ = *(reinterpret_cast<void**>(preamble_page->free_));
-  return ret;
-}
-
-void PreamblePatcher::FreePreambleBlock(unsigned char* block) {
-  SIDESTEP_ASSERT(block != NULL);
-  SIDESTEP_ASSERT(granularity_ != 0);
-  uintptr_t ptr = reinterpret_cast<uintptr_t>(block);
-  ptr -= ptr & (granularity_ - 1);
-  PreamblePage* preamble_page = reinterpret_cast<PreamblePage*>(ptr);
-  SIDESTEP_ASSERT(preamble_page->magic_ == kPreamblePageMagic);
-  *(reinterpret_cast<void**>(block)) = preamble_page->free_;
-  preamble_page->free_ = block;
-}
-
-void* PreamblePatcher::AllocPageNear(void* target) {
-  MEMORY_BASIC_INFORMATION mbi = { 0 };
-  if (!::VirtualQuery(target, &mbi, sizeof(mbi))) {
-    SIDESTEP_ASSERT(false && "VirtualQuery failed on target address");
-    return 0;
-  }
-  if (initialized_ == false) {
-    PreamblePatcher::Initialize();
-    SIDESTEP_ASSERT(initialized_);
-  }
-  void* pv = NULL;
-  unsigned char* allocation_base = reinterpret_cast<unsigned char*>(
-      mbi.AllocationBase);
-  __int64 i = 1;
-  bool high_target = reinterpret_cast<__int64>(target) > UINT_MAX;
-  while (pv == NULL) {
-    __int64 val = reinterpret_cast<__int64>(allocation_base) -
-        (i * granularity_);
-    if (high_target &&
-        reinterpret_cast<__int64>(target) - val > INT_MAX) {
-        // We're further than 2GB from the target
-      break;
-    } else if (val <= NULL) {
-      // Less than 0
-      break;
-    }
-    pv = ::VirtualAlloc(reinterpret_cast<void*>(allocation_base -
-                            (i++ * granularity_)),
-                        pagesize_, MEM_COMMIT | MEM_RESERVE,
-                        PAGE_EXECUTE_READWRITE);
-  }
-
-  // We couldn't allocate low, try to allocate high
-  if (pv == NULL) {
-    i = 1;
-    // Round up to the next multiple of page granularity
-    allocation_base = reinterpret_cast<unsigned char*>(
-        (reinterpret_cast<__int64>(target) &
-        (~(granularity_ - 1))) + granularity_);
-    while (pv == NULL) {
-      __int64 val = reinterpret_cast<__int64>(allocation_base) +
-          (i * granularity_) - reinterpret_cast<__int64>(target);
-      if (val > INT_MAX || val < 0) {
-        // We're too far or we overflowed
-        break;
-      }
-      pv = ::VirtualAlloc(reinterpret_cast<void*>(allocation_base +
-                              (i++ * granularity_)),
-                          pagesize_, MEM_COMMIT | MEM_RESERVE,
-                          PAGE_EXECUTE_READWRITE);
-    }
-  }
-  return pv;
-}
-
-bool PreamblePatcher::IsShortConditionalJump(
-    unsigned char* target,
-    unsigned int instruction_size) {
-  return (*(target) & 0x70) == 0x70 && instruction_size == 2;
-}
-
-bool PreamblePatcher::IsNearConditionalJump(
-    unsigned char* target,
-    unsigned int instruction_size) {
-  return *(target) == 0xf && (*(target + 1) & 0x80) == 0x80 &&
-      instruction_size == 6;
-}
-
-bool PreamblePatcher::IsNearRelativeJump(
-    unsigned char* target,
-    unsigned int instruction_size) {
-  return *(target) == 0xe9 && instruction_size == 5;
-}
-
-bool PreamblePatcher::IsNearAbsoluteCall(
-    unsigned char* target,
-    unsigned int instruction_size) {
-  return *(target) == 0xff && (*(target + 1) & 0x10) == 0x10 &&
-      instruction_size == 6;
-}
-
-bool PreamblePatcher::IsNearRelativeCall(
-    unsigned char* target,
-    unsigned int instruction_size) {
-  return *(target) == 0xe8 && instruction_size == 5;
-}
-
-bool PreamblePatcher::IsMovWithDisplacement(
-    unsigned char* target,
-    unsigned int instruction_size) {
-  // In this case, the ModRM byte's mod field will be 0 and r/m will be 101b (5)
-  return instruction_size == 7 && *target == 0x48 && *(target + 1) == 0x8b &&
-      (*(target + 2) >> 6) == 0 && (*(target + 2) & 0x7) == 5;
-}
-
-SideStepError PreamblePatcher::PatchShortConditionalJump(
-    unsigned char* source,
-    unsigned int instruction_size,
-    unsigned char* target,
-    unsigned int* target_bytes,
-    unsigned int target_size) {
-  unsigned char* original_jump_dest = (source + 2) + source[1];
-  unsigned char* stub_jump_from = target + 6;
-  __int64 fixup_jump_offset = original_jump_dest - stub_jump_from;
-  if (fixup_jump_offset > INT_MAX || fixup_jump_offset < INT_MIN) {
-    SIDESTEP_ASSERT(false &&
-                    "Unable to fix up short jump because target"
-                    " is too far away.");
-    return SIDESTEP_JUMP_INSTRUCTION;
-  }
-
-  *target_bytes = 6;
-  if (target_size > *target_bytes) {
-    // Convert the short jump to a near jump.
-    //
-    // 0f 8x xx xx xx xx = Jcc rel32off
-    unsigned short jmpcode = ((0x80 | (source[0] & 0xf)) << 8) | 0x0f;
-    memcpy(reinterpret_cast<void*>(target),
-           reinterpret_cast<void*>(&jmpcode), 2);
-    memcpy(reinterpret_cast<void*>(target + 2),
-           reinterpret_cast<void*>(&fixup_jump_offset), 4);
-  }
-
-  return SIDESTEP_SUCCESS;
-}
-
-SideStepError PreamblePatcher::PatchNearJumpOrCall(
-    unsigned char* source,
-    unsigned int instruction_size,
-    unsigned char* target,
-    unsigned int* target_bytes,
-    unsigned int target_size) {
-  SIDESTEP_ASSERT(instruction_size == 5 || instruction_size == 6);
-  unsigned int jmp_offset_in_instruction = instruction_size == 5 ? 1 : 2;
-  unsigned char* original_jump_dest = reinterpret_cast<unsigned char *>(
-      reinterpret_cast<__int64>(source + instruction_size) +
-      *(reinterpret_cast<int*>(source + jmp_offset_in_instruction)));
-  unsigned char* stub_jump_from = target + instruction_size;
-  __int64 fixup_jump_offset = original_jump_dest - stub_jump_from;
-  if (fixup_jump_offset > INT_MAX || fixup_jump_offset < INT_MIN) {
-    SIDESTEP_ASSERT(false &&
-                    "Unable to fix up near jump because target"
-                    " is too far away.");
-    return SIDESTEP_JUMP_INSTRUCTION;
-  }
-
-  if ((fixup_jump_offset < SCHAR_MAX && fixup_jump_offset > SCHAR_MIN)) {
-    *target_bytes = 2;
-    if (target_size > *target_bytes) {
-      // If the new offset is in range, use a short jump instead of a near jump.
-      if (source[0] == ASM_JCC32REL_0 &&
-          (source[1] & ASM_JCC32REL_1_MASK) == ASM_JCC32REL_1_MASK) {
-        unsigned short jmpcode = (static_cast<unsigned char>(
-            fixup_jump_offset) << 8) | (0x70 | (source[1] & 0xf));
-        memcpy(reinterpret_cast<void*>(target),
-               reinterpret_cast<void*>(&jmpcode),
-               2);
-      } else {
-        target[0] = ASM_JMP8REL;
-        target[1] = static_cast<unsigned char>(fixup_jump_offset);
-      }
-    }
-  } else {
-    *target_bytes = instruction_size;
-    if (target_size > *target_bytes) {
-      memcpy(reinterpret_cast<void*>(target),
-             reinterpret_cast<void*>(source),
-             jmp_offset_in_instruction);
-      memcpy(reinterpret_cast<void*>(target + jmp_offset_in_instruction),
-             reinterpret_cast<void*>(&fixup_jump_offset),
-             4);
-    }
-  }
-
-  return SIDESTEP_SUCCESS;
-}
-
-SideStepError PreamblePatcher::PatchMovWithDisplacement(
-     unsigned char* source,
-     unsigned int instruction_size,
-     unsigned char* target,
-     unsigned int* target_bytes,
-     unsigned int target_size) {
-  SIDESTEP_ASSERT(instruction_size == 7);
-  const int mov_offset_in_instruction = 3; // 0x48 0x8b 0x0d <offset>
-  unsigned char* original_mov_dest = reinterpret_cast<unsigned char*>(
-      reinterpret_cast<__int64>(source + instruction_size) +
-      *(reinterpret_cast<int*>(source + mov_offset_in_instruction)));
-  unsigned char* stub_mov_from = target + instruction_size;
-  __int64 fixup_mov_offset = original_mov_dest - stub_mov_from;
-  if (fixup_mov_offset > INT_MAX || fixup_mov_offset < INT_MIN) {
-    SIDESTEP_ASSERT(false &&
-        "Unable to fix up near MOV because target is too far away.");
-    return SIDESTEP_UNEXPECTED;
-  }
-  *target_bytes = instruction_size;
-  if (target_size > *target_bytes) {
-    memcpy(reinterpret_cast<void*>(target),
-           reinterpret_cast<void*>(source),
-           mov_offset_in_instruction);
-    memcpy(reinterpret_cast<void*>(target + mov_offset_in_instruction),
-           reinterpret_cast<void*>(&fixup_mov_offset),
-           4);
-  }
-  return SIDESTEP_SUCCESS;
-}
-
 };  // namespace sidestep