1 files changed, 180 insertions, 0 deletions
diff --git a/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp b/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
new file mode 100644
index 000000000000..b2628dcc4dc1
--- /dev/null
+++ b/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
@@ -0,0 +1,180 @@
+//===-- sanitizer_unwind_linux_libcdep.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the unwind.h-based (aka "slow") stack unwinding routines
+// available to the tools on Linux, Android, NetBSD, FreeBSD, and Solaris.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
+    SANITIZER_SOLARIS
+#include "sanitizer_common.h"
+#include "sanitizer_stacktrace.h"
+
+#if SANITIZER_ANDROID
+#include <dlfcn.h>  // for dlopen()
+#endif
+
+#if SANITIZER_FREEBSD
+#define _GNU_SOURCE  // to declare _Unwind_Backtrace() from <unwind.h>
+#endif
+#include <unwind.h>
+
+namespace __sanitizer {
+
+namespace {
+
+//---------------------------- UnwindSlow --------------------------------------
+
+typedef struct {
+  uptr absolute_pc;
+  uptr stack_top;
+  uptr stack_size;
+} backtrace_frame_t;
+
+extern "C" {
+typedef void *(*acquire_my_map_info_list_func)();
+typedef void (*release_my_map_info_list_func)(void *map);
+typedef sptr (*unwind_backtrace_signal_arch_func)(
+    void *siginfo, void *sigcontext, void *map_info_list,
+    backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
+acquire_my_map_info_list_func acquire_my_map_info_list;
+release_my_map_info_list_func release_my_map_info_list;
+unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
+} // extern "C"
+
+#if defined(__arm__) && !SANITIZER_NETBSD
+// NetBSD uses dwarf EH
+#define UNWIND_STOP _URC_END_OF_STACK
+#define UNWIND_CONTINUE _URC_NO_REASON
+#else
+#define UNWIND_STOP _URC_NORMAL_STOP
+#define UNWIND_CONTINUE _URC_NO_REASON
+#endif
+
+uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
+#if defined(__arm__) && !SANITIZER_MAC
+  uptr val;
+  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
+      15 /* r15 = PC */, _UVRSD_UINT32, &val);
+  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
+  // Clear the Thumb bit.
+  return val & ~(uptr)1;
+#else
+  return (uptr)_Unwind_GetIP(ctx);
+#endif
+}
+
+struct UnwindTraceArg {
+  BufferedStackTrace *stack;
+  u32 max_depth;
+};
+
+_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
+  UnwindTraceArg *arg = (UnwindTraceArg*)param;
+  CHECK_LT(arg->stack->size, arg->max_depth);
+  uptr pc = Unwind_GetIP(ctx);
+  const uptr kPageSize = GetPageSizeCached();
+  // Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and
+  // x86_64) is invalid and stop unwinding here.  If we're adding support for
+  // a platform where this isn't true, we need to reconsider this check.
+  if (pc < kPageSize) return UNWIND_STOP;
+  arg->stack->trace_buffer[arg->stack->size++] = pc;
+  if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
+  return UNWIND_CONTINUE;
+}
+
+}  // namespace
+
+#if SANITIZER_ANDROID
+void SanitizerInitializeUnwinder() {
+  if (AndroidGetApiLevel() >= ANDROID_LOLLIPOP_MR1) return;
+
+  // Pre-lollipop Android can not unwind through signal handler frames with
+  // libgcc unwinder, but it has a libcorkscrew.so library with the necessary
+  // workarounds.
+  void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
+  if (!p) {
+    VReport(1,
+            "Failed to open libcorkscrew.so. You may see broken stack traces "
+            "in SEGV reports.");
+    return;
+  }
+  acquire_my_map_info_list =
+      (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
+  release_my_map_info_list =
+      (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
+  unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
+      p, "unwind_backtrace_signal_arch");
+  if (!acquire_my_map_info_list || !release_my_map_info_list ||
+      !unwind_backtrace_signal_arch) {
+    VReport(1,
+            "Failed to find one of the required symbols in libcorkscrew.so. "
+            "You may see broken stack traces in SEGV reports.");
+    acquire_my_map_info_list = 0;
+    unwind_backtrace_signal_arch = 0;
+    release_my_map_info_list = 0;
+  }
+}
+#endif
+
+void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
+  CHECK_GE(max_depth, 2);
+  size = 0;
+  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
+  _Unwind_Backtrace(Unwind_Trace, &arg);
+  // We need to pop a few frames so that pc is on top.
+  uptr to_pop = LocatePcInTrace(pc);
+  // trace_buffer[0] belongs to the current function so we always pop it,
+  // unless there is only 1 frame in the stack trace (1 frame is always better
+  // than 0!).
+  // 1-frame stacks don't normally happen, but this depends on the actual
+  // unwinder implementation (libgcc, libunwind, etc) which is outside of our
+  // control.
+  if (to_pop == 0 && size > 1)
+    to_pop = 1;
+  PopStackFrames(to_pop);
+#if defined(__GNUC__) && defined(__sparc__)
+  // __builtin_return_address returns the address of the call instruction
+  // on the SPARC and not the return address, so we need to compensate.
+  trace_buffer[0] = GetNextInstructionPc(pc);
+#else
+  trace_buffer[0] = pc;
+#endif
+}
+
+void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {
+  CHECK(context);
+  CHECK_GE(max_depth, 2);
+  if (!unwind_backtrace_signal_arch) {
+    UnwindSlow(pc, max_depth);
+    return;
+  }
+
+  void *map = acquire_my_map_info_list();
+  CHECK(map);
+  InternalMmapVector<backtrace_frame_t> frames(kStackTraceMax);
+  // siginfo argument appears to be unused.
+  sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map,
+                                          frames.data(),
+                                          /* ignore_depth */ 0, max_depth);
+  release_my_map_info_list(map);
+  if (res < 0) return;
+  CHECK_LE((uptr)res, kStackTraceMax);
+
+  size = 0;
+  // +2 compensate for libcorkscrew unwinder returning addresses of call
+  // instructions instead of raw return addresses.
+  for (sptr i = 0; i < res; ++i)
+    trace_buffer[size++] = frames[i].absolute_pc + 2;
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||
+        // SANITIZER_SOLARIS