Index: tools/memory_watcher/preamble_patcher_with_stub.cc |
diff --git a/tools/memory_watcher/preamble_patcher_with_stub.cc b/tools/memory_watcher/preamble_patcher_with_stub.cc |
deleted file mode 100644 |
index 31303065c36e9faad5812f08bceb9969318d66b5..0000000000000000000000000000000000000000 |
--- a/tools/memory_watcher/preamble_patcher_with_stub.cc |
+++ /dev/null |
@@ -1,174 +0,0 @@ |
-// Copyright (c) 2012 The Chromium Authors. All rights reserved. |
-// Use of this source code is governed by a BSD-style license that can be |
-// found in the LICENSE file. |
- |
-/* |
- * Implementation of PreamblePatcher |
- */ |
- |
-#include "preamble_patcher.h" |
- |
-#include "mini_disassembler.h" |
- |
-// Definitions of assembly statements we need |
-#define ASM_JMP32REL 0xE9 |
-#define ASM_INT3 0xCC |
- |
-namespace sidestep { |
- |
-SideStepError PreamblePatcher::RawPatchWithStub( |
- void* target_function, |
- void *replacement_function, |
- unsigned char* preamble_stub, |
- unsigned long stub_size, |
- unsigned long* bytes_needed) { |
- if ((NULL == target_function) || |
- (NULL == replacement_function) || |
- (NULL == preamble_stub)) { |
- ASSERT(false, "Invalid parameters - either pTargetFunction or " |
- "pReplacementFunction or pPreambleStub were NULL."); |
- return SIDESTEP_INVALID_PARAMETER; |
- } |
- |
- // TODO(V7:joi) Siggi and I just had a discussion and decided that both |
- // patching and unpatching are actually unsafe. We also discussed a |
- // method of making it safe, which is to freeze all other threads in the |
- // process, check their thread context to see if their eip is currently |
- // inside the block of instructions we need to copy to the stub, and if so |
- // wait a bit and try again, then unfreeze all threads once we've patched. |
- // Not implementing this for now since we're only using SideStep for unit |
- // testing, but if we ever use it for production code this is what we |
- // should do. |
- // |
- // NOTE: Stoyan suggests we can write 8 or even 10 bytes atomically using |
- // FPU instructions, and on newer processors we could use cmpxchg8b or |
- // cmpxchg16b. So it might be possible to do the patching/unpatching |
- // atomically and avoid having to freeze other threads. Note though, that |
- // doing it atomically does not help if one of the other threads happens |
- // to have its eip in the middle of the bytes you change while you change |
- // them. |
- unsigned char* target = reinterpret_cast<unsigned char*>(target_function); |
- |
- // 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. |
- 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 |
- ASSERT1(sizeof(relative_offset) == 4); |
- memcpy(reinterpret_cast<void*>(&relative_offset), |
- reinterpret_cast<void*>(target + 1), 4); |
- // I'd like to just say "target = target + 5 + relative_offset" here, but |
- // I can't, because the new target will need to have its protections set. |
- return RawPatchWithStubAndProtections(target + 5 + relative_offset, |
- replacement_function, preamble_stub, |
- stub_size, bytes_needed); |
- } |
- |
- // Let's disassemble the preamble of the target function to see if we can |
- // patch, and to see how much of the preamble we need to take. We need 5 |
- // bytes for our jmp instruction, so let's find the minimum number of |
- // instructions to get 5 bytes. |
- MiniDisassembler disassembler; |
- unsigned int preamble_bytes = 0; |
- while (preamble_bytes < 5) { |
- InstructionType instruction_type = |
- disassembler.Disassemble(target + preamble_bytes, preamble_bytes); |
- if (IT_JUMP == instruction_type) { |
- ASSERT(false, "Unable to patch because there is a jump instruction " |
- "in the first 5 bytes."); |
- return SIDESTEP_JUMP_INSTRUCTION; |
- } else if (IT_RETURN == instruction_type) { |
- ASSERT(false, "Unable to patch because function is too short"); |
- return SIDESTEP_FUNCTION_TOO_SMALL; |
- } else if (IT_GENERIC != instruction_type) { |
- ASSERT(false, "Disassembler encountered unsupported instruction " |
- "(either unused or unknown)"); |
- return SIDESTEP_UNSUPPORTED_INSTRUCTION; |
- } |
- } |
- |
- if (NULL != bytes_needed) |
- *bytes_needed = preamble_bytes + 5; |
- |
- // Inv: cbPreamble is the number of bytes (at least 5) that we need to take |
- // from the preamble to have whole instructions that are 5 bytes or more |
- // in size total. The size of the stub required is cbPreamble + size of |
- // jmp (5) |
- if (preamble_bytes + 5 > stub_size) { |
- ASSERT1(false); |
- return SIDESTEP_INSUFFICIENT_BUFFER; |
- } |
- |
- // First, copy the preamble that we will overwrite. |
- memcpy(reinterpret_cast<void*>(preamble_stub), |
- reinterpret_cast<void*>(target), preamble_bytes); |
- |
- // Now, make a jmp instruction to the rest of the target function (minus the |
- // preamble bytes we moved into the stub) and copy it into our preamble-stub. |
- // find address to jump to, relative to next address after jmp instruction |
-#ifdef _MSC_VER |
-#pragma warning(push) |
-#pragma warning(disable:4244) |
-#endif |
- int relative_offset_to_target_rest |
- = ((reinterpret_cast<unsigned char*>(target) + preamble_bytes) - |
- (preamble_stub + preamble_bytes + 5)); |
-#ifdef _MSC_VER |
-#pragma warning(pop) |
-#endif |
- // jmp (Jump near, relative, displacement relative to next instruction) |
- preamble_stub[preamble_bytes] = ASM_JMP32REL; |
- // copy the address |
- memcpy(reinterpret_cast<void*>(preamble_stub + preamble_bytes + 1), |
- reinterpret_cast<void*>(&relative_offset_to_target_rest), 4); |
- |
- // Inv: preamble_stub points to assembly code that will execute the |
- // original function by first executing the first cbPreamble bytes of the |
- // preamble, then jumping to the rest of the function. |
- |
- // Overwrite the first 5 bytes of the target function with a jump to our |
- // replacement function. |
- // (Jump near, relative, displacement relative to next instruction) |
- target[0] = ASM_JMP32REL; |
- |
- // Find offset from instruction after jmp, to the replacement function. |
-#ifdef _MSC_VER |
-#pragma warning(push) |
-#pragma warning(disable:4244) |
-#endif |
- int offset_to_replacement_function = |
- reinterpret_cast<unsigned char*>(replacement_function) - |
- reinterpret_cast<unsigned char*>(target) - 5; |
-#ifdef _MSC_VER |
-#pragma warning(pop) |
-#endif |
- // complete the jmp instruction |
- memcpy(reinterpret_cast<void*>(target + 1), |
- reinterpret_cast<void*>(&offset_to_replacement_function), 4); |
- // Set any remaining bytes that were moved to the preamble-stub to INT3 so |
- // as not to cause confusion (otherwise you might see some strange |
- // instructions if you look at the disassembly, or even invalid |
- // instructions). Also, by doing this, we will break into the debugger if |
- // some code calls into this portion of the code. If this happens, it |
- // means that this function cannot be patched using this patcher without |
- // further thought. |
- if (preamble_bytes > 5) { |
- memset(reinterpret_cast<void*>(target + 5), ASM_INT3, preamble_bytes - 5); |
- } |
- |
- // Inv: The memory pointed to by target_function now points to a relative |
- // jump instruction that jumps over to the preamble_stub. The preamble |
- // stub contains the first stub_size bytes of the original target |
- // function's preamble code, followed by a relative jump back to the next |
- // instruction after the first cbPreamble bytes. |
- |
- return SIDESTEP_SUCCESS; |
-} |
- |
-}; // namespace sidestep |