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#include "xray_interface_internal.h"
#include "sanitizer_common/sanitizer_common.h"
#include <atomic>
#include <cstdint>
#include <limits>
namespace __xray {
static constexpr uint8_t CallOpCode = 0xe8;
static constexpr uint16_t MovR10Seq = 0xba41;
static constexpr uint16_t Jmp9Seq = 0x09eb;
static constexpr uint8_t JmpOpCode = 0xe9;
static constexpr uint8_t RetOpCode = 0xc3;
static constexpr int64_t MinOffset{std::numeric_limits<int32_t>::min()};
static constexpr int64_t MaxOffset{std::numeric_limits<int32_t>::max()};
bool patchFunctionEntry(const bool Enable, const uint32_t FuncId, const XRaySledEntry& Sled)
{
// Here we do the dance of replacing the following sled:
//
// xray_sled_n:
// jmp +9
// <9 byte nop>
//
// With the following:
//
// mov r10d, <function id>
// call <relative 32bit offset to entry trampoline>
//
// We need to do this in the following order:
//
// 1. Put the function id first, 2 bytes from the start of the sled (just
// after the 2-byte jmp instruction).
// 2. Put the call opcode 6 bytes from the start of the sled.
// 3. Put the relative offset 7 bytes from the start of the sled.
// 4. Do an atomic write over the jmp instruction for the "mov r10d"
// opcode and first operand.
//
// Prerequisite is to compute the relative offset to the
// __xray_FunctionEntry function's address.
int64_t TrampolineOffset =
reinterpret_cast<int64_t>(__xray_FunctionEntry) -
(static_cast<int64_t>(Sled.Address) + 11);
if (TrampolineOffset < MinOffset || TrampolineOffset > MaxOffset) {
Report("XRay Entry trampoline (%p) too far from sled (%p); distance = "
"%ld\n",
__xray_FunctionEntry, reinterpret_cast<void *>(Sled.Address),
TrampolineOffset);
return false;
}
if (Enable) {
*reinterpret_cast<uint32_t *>(Sled.Address + 2) = FuncId;
*reinterpret_cast<uint8_t *>(Sled.Address + 6) = CallOpCode;
*reinterpret_cast<uint32_t *>(Sled.Address + 7) = TrampolineOffset;
std::atomic_store_explicit(
reinterpret_cast<std::atomic<uint16_t> *>(Sled.Address), MovR10Seq,
std::memory_order_release);
} else {
std::atomic_store_explicit(
reinterpret_cast<std::atomic<uint16_t> *>(Sled.Address), Jmp9Seq,
std::memory_order_release);
// FIXME: Write out the nops still?
}
return true;
}
bool patchFunctionExit(const bool Enable, const uint32_t FuncId, const XRaySledEntry& Sled)
{
// Here we do the dance of replacing the following sled:
//
// xray_sled_n:
// ret
// <10 byte nop>
//
// With the following:
//
// mov r10d, <function id>
// jmp <relative 32bit offset to exit trampoline>
//
// 1. Put the function id first, 2 bytes from the start of the sled (just
// after the 1-byte ret instruction).
// 2. Put the jmp opcode 6 bytes from the start of the sled.
// 3. Put the relative offset 7 bytes from the start of the sled.
// 4. Do an atomic write over the jmp instruction for the "mov r10d"
// opcode and first operand.
//
// Prerequisite is to compute the relative offset fo the
// __xray_FunctionExit function's address.
int64_t TrampolineOffset =
reinterpret_cast<int64_t>(__xray_FunctionExit) -
(static_cast<int64_t>(Sled.Address) + 11);
if (TrampolineOffset < MinOffset || TrampolineOffset > MaxOffset) {
Report("XRay Exit trampoline (%p) too far from sled (%p); distance = "
"%ld\n",
__xray_FunctionExit, reinterpret_cast<void *>(Sled.Address),
TrampolineOffset);
return false;
}
if (Enable) {
*reinterpret_cast<uint32_t *>(Sled.Address + 2) = FuncId;
*reinterpret_cast<uint8_t *>(Sled.Address + 6) = JmpOpCode;
*reinterpret_cast<uint32_t *>(Sled.Address + 7) = TrampolineOffset;
std::atomic_store_explicit(
reinterpret_cast<std::atomic<uint16_t> *>(Sled.Address), MovR10Seq,
std::memory_order_release);
} else {
std::atomic_store_explicit(
reinterpret_cast<std::atomic<uint8_t> *>(Sled.Address), RetOpCode,
std::memory_order_release);
// FIXME: Write out the nops still?
}
return true;
}
} // namespace __xray
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