[XRay] ARM 32-bit no-Thumb support in compiler-rt

This is a port of XRay to ARM 32-bit, without Thumb support yet.
This is one of 3 commits to different repositories of XRay ARM port. The
other 2 are:

1. https://reviews.llvm.org/D23931 (LLVM)
2. https://reviews.llvm.org/D23932 (Clang test)

Differential Revision: https://reviews.llvm.org/D23933

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@280890 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 116 insertions, 0 deletions

diff --git a/lib/xray/xray_x86_64.cc b/lib/xray/xray_x86_64.cc
new file mode 100644
index 000000000..398d6fc14
--- /dev/null
+++ b/lib/xray/xray_x86_64.cc
@@ -0,0 +1,116 @@
+#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