1 files changed, 202 insertions, 0 deletions
diff --git a/lib/xray/xray_x86_64.cc b/lib/xray/xray_x86_64.cc
new file mode 100644
index 0000000000000..3ee91896c6e0a
--- /dev/null
+++ b/lib/xray/xray_x86_64.cc
@@ -0,0 +1,202 @@
+#include "sanitizer_common/sanitizer_common.h"
+#include "xray_defs.h"
+#include "xray_interface_internal.h"
+#include <atomic>
+#include <cstdint>
+#include <errno.h>
+#include <fcntl.h>
+#include <iterator>
+#include <limits>
+#include <tuple>
+#include <unistd.h>
+
+namespace __xray {
+
+static std::pair<ssize_t, bool>
+retryingReadSome(int Fd, char *Begin, char *End) XRAY_NEVER_INSTRUMENT {
+  auto BytesToRead = std::distance(Begin, End);
+  ssize_t BytesRead;
+  ssize_t TotalBytesRead = 0;
+  while (BytesToRead && (BytesRead = read(Fd, Begin, BytesToRead))) {
+    if (BytesRead == -1) {
+      if (errno == EINTR)
+        continue;
+      Report("Read error; errno = %d\n", errno);
+      return std::make_pair(TotalBytesRead, false);
+    }
+
+    TotalBytesRead += BytesRead;
+    BytesToRead -= BytesRead;
+    Begin += BytesRead;
+  }
+  return std::make_pair(TotalBytesRead, true);
+}
+
+static bool readValueFromFile(const char *Filename,
+                              long long *Value) XRAY_NEVER_INSTRUMENT {
+  int Fd = open(Filename, O_RDONLY | O_CLOEXEC);
+  if (Fd == -1)
+    return false;
+  static constexpr size_t BufSize = 256;
+  char Line[BufSize] = {};
+  ssize_t BytesRead;
+  bool Success;
+  std::tie(BytesRead, Success) = retryingReadSome(Fd, Line, Line + BufSize);
+  if (!Success)
+    return false;
+  close(Fd);
+  char *End = nullptr;
+  long long Tmp = internal_simple_strtoll(Line, &End, 10);
+  bool Result = false;
+  if (Line[0] != '\0' && (*End == '\n' || *End == '\0')) {
+    *Value = Tmp;
+    Result = true;
+  }
+  return Result;
+}
+
+uint64_t cycleFrequency() XRAY_NEVER_INSTRUMENT {
+  long long CPUFrequency = -1;
+  if (readValueFromFile("/sys/devices/system/cpu/cpu0/tsc_freq_khz",
+                        &CPUFrequency)) {
+    CPUFrequency *= 1000;
+  } else if (readValueFromFile(
+      "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq",
+      &CPUFrequency)) {
+    CPUFrequency *= 1000;
+  } else {
+    Report("Unable to determine CPU frequency for TSC accounting.\n");
+  }
+  return CPUFrequency == -1 ? 0 : static_cast<uint64_t>(CPUFrequency);
+}
+
+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) XRAY_NEVER_INSTRUMENT {
+  // 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)\n",
+           __xray_FunctionEntry, reinterpret_cast<void *>(Sled.Address));
+    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) XRAY_NEVER_INSTRUMENT {
+  // 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)\n",
+           __xray_FunctionExit, reinterpret_cast<void *>(Sled.Address));
+    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;
+}
+
+bool patchFunctionTailExit(const bool Enable, const uint32_t FuncId,
+                           const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
+  // Here we do the dance of replacing the tail call sled with a similar
+  // sequence as the entry sled, but calls the tail exit sled instead.
+  int64_t TrampolineOffset =
+      reinterpret_cast<int64_t>(__xray_FunctionTailExit) -
+      (static_cast<int64_t>(Sled.Address) + 11);
+  if (TrampolineOffset < MinOffset || TrampolineOffset > MaxOffset) {
+    Report("XRay Exit trampoline (%p) too far from sled (%p)\n",
+           __xray_FunctionExit, reinterpret_cast<void *>(Sled.Address));
+    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;
+}
+
+} // namespace __xray