Reland "Reland "Mac: use frame-pointer unwind for macOS 10.14+ and ARM""

This is a reland of 62de5d0

Previous reland didn't include https://chromium-review.googlesource.com/c/chromium/src/+/3465714

Original change's description:
> Reland "Mac: use frame-pointer unwind for macOS 10.14+ and ARM"
>
> This is a reland of 1fe207f
>
> Fix in patchset 2
>
> Original change's description:
> > Mac: use frame-pointer unwind for macOS 10.14+ and ARM
> >
> > This change keeps NativeMacUnwinder for now. In a future change
> > (possibly after this bakes), we can backport pthread_stack_frame_decode_np
> > and remove it.
> >
> > For convenience, since I renamed the file, here's a separate diff
> > of TryUnwind: https://gist.github.com/speednoisemovement/5545f236ebe674360528895d1ae5c0de
> >
> > Bug: 1101399, 1102197
> > Change-Id: Id2ca3f8e34d5f91d9adc668831a3f1ea7b46b1ad
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3336376
> > Reviewed-by: David Jean <djean@chromium.org>
> > Reviewed-by: Mike Wittman <wittman@chromium.org>
> > Reviewed-by: Eric Seckler <eseckler@chromium.org>
> > Commit-Queue: Leonard Grey <lgrey@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#971214}
>
> Bug: 1101399, 1102197
> Change-Id: If8446743a5b82cd54ca620f575c4d0ea4efeab42
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3466814
> Reviewed-by: Mike Wittman <wittman@chromium.org>
> Reviewed-by: David Jean <djean@chromium.org>
> Reviewed-by: Eric Seckler <eseckler@chromium.org>
> Commit-Queue: Leonard Grey <lgrey@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#972478}

Bug: 1101399, 1102197
Change-Id: Ie40d25a9e2ac67cfe5f314b8d2718f4fd1d23c7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3472124
Auto-Submit: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Mike Wittman <wittman@chromium.org>
Reviewed-by: Eric Seckler <eseckler@chromium.org>
Commit-Queue: Eric Seckler <eseckler@chromium.org>
Cr-Commit-Position: refs/heads/main@{#972861}

base/BUILD.gn

@@ -1263,6 +1263,8 @@ mixed_component("base") {
       "process/process_mac.cc",
       "process/process_metrics_mac.cc",
       "profiler/module_cache_mac.cc",
+      "profiler/native_unwinder_apple.cc",
+      "profiler/native_unwinder_apple.h",
       "profiler/native_unwinder_mac.cc",
       "profiler/native_unwinder_mac.h",
       "profiler/stack_sampler_mac.cc",
@@ -1310,8 +1312,8 @@ mixed_component("base") {
 
     if (ios_stack_profiler_enabled) {
       sources += [
-        "profiler/native_unwinder_ios.cc",
-        "profiler/native_unwinder_ios.h",
+        "profiler/native_unwinder_apple.cc",
+        "profiler/native_unwinder_apple.h",
         "profiler/suspendable_thread_delegate_mac.cc",
         "profiler/suspendable_thread_delegate_mac.h",
       ]
@@ -3817,6 +3819,9 @@ test("base_unittests") {
     }
     sources += [ "files/os_validation_win_unittest.cc" ]
   }
+  if (is_apple) {
+    sources += [ "profiler/native_unwinder_apple_unittest.cc" ]
+  }
 
   if (use_allocator_shim) {
     sources += [

base/profiler/native_unwinder_apple.cc

@@ -0,0 +1,92 @@
+// Copyright 2021 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.
+
+#include "base/profiler/native_unwinder_apple.h"
+
+#include <pthread/stack_np.h>
+
+#include "base/check_op.h"
+#include "base/notreached.h"
+#include "base/numerics/clamped_math.h"
+#include "base/profiler/module_cache.h"
+#include "base/profiler/native_unwinder.h"
+#include "build/build_config.h"
+
+namespace base {
+
+NativeUnwinderApple::NativeUnwinderApple() = default;
+
+bool NativeUnwinderApple::CanUnwindFrom(const Frame& current_frame) const {
+  return current_frame.module && current_frame.module->IsNative();
+}
+
+UnwindResult NativeUnwinderApple::TryUnwind(RegisterContext* thread_context,
+                                            uintptr_t stack_top,
+                                            std::vector<Frame>* stack) const {
+  // We expect the frame corresponding to the |thread_context| register state to
+  // exist within |stack|.
+  DCHECK_GT(stack->size(), 0u);
+#if defined(ARCH_CPU_ARM64)
+  constexpr uintptr_t align_mask = 0x1;
+#elif defined(ARCH_CPU_X86_64)
+  constexpr uintptr_t align_mask = 0xf;
+#endif
+
+  uintptr_t next_frame = RegisterContextFramePointer(thread_context);
+  uintptr_t frame_lower_bound = RegisterContextStackPointer(thread_context);
+  const auto is_fp_valid = [&](uintptr_t fp) {
+    // Ensure there's space on the stack to read two values: the caller's
+    // frame pointer and the return address.
+    return next_frame >= frame_lower_bound &&
+           ClampAdd(next_frame, sizeof(uintptr_t) * 2) <= stack_top &&
+           (next_frame & align_mask) == 0;
+  };
+  if (!is_fp_valid(next_frame))
+    return UnwindResult::kAborted;
+
+  for (;;) {
+    if (!stack->back().module) {
+      return UnwindResult::kAborted;
+    }
+    if (!stack->back().module->IsNative()) {
+      // This is a non-native module associated with the auxiliary unwinder
+      // (e.g. corresponding to a frame in V8 generated code). Report as
+      // UNRECOGNIZED_FRAME to allow that unwinder to unwind the frame.
+      return UnwindResult::kUnrecognizedFrame;
+    }
+    uintptr_t retaddr;
+    uintptr_t frame = next_frame;
+    next_frame = pthread_stack_frame_decode_np(frame, &retaddr);
+    frame_lower_bound = frame + 1;
+    // If `next_frame` is 0, we've hit the root and `retaddr` isn't useful.
+    // Bail without recording the frame.
+    if (next_frame == 0)
+      return UnwindResult::kCompleted;
+    const ModuleCache::Module* module =
+        module_cache()->GetModuleForAddress(retaddr);
+    // V8 doesn't conform to the x86_64 ABI re: stack alignment. For V8 frames,
+    // let the V8 unwinder determine whether the FP is valid or not.
+    bool is_non_native_module = module && !module->IsNative();
+    // If the FP doesn't look correct, don't record this frame.
+    if (!is_non_native_module && !is_fp_valid(next_frame))
+      return UnwindResult::kAborted;
+
+    RegisterContextFramePointer(thread_context) = next_frame;
+    RegisterContextInstructionPointer(thread_context) = retaddr;
+    RegisterContextStackPointer(thread_context) = frame + sizeof(uintptr_t) * 2;
+    stack->emplace_back(retaddr, module);
+  }
+
+  NOTREACHED();
+  return UnwindResult::kCompleted;
+}
+
+// Mac version is defined in NativeUnwinderMac
+#if BUILDFLAG(IS_IOS)
+std::unique_ptr<Unwinder> CreateNativeUnwinder(ModuleCache* module_cache) {
+  return std::make_unique<NativeUnwinderApple>();
+}
+#endif
+
+}  // namespace base

base/profiler/native_unwinder_apple.h

@@ -0,0 +1,35 @@
+// Copyright 2021 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.
+
+#ifndef BASE_PROFILER_NATIVE_UNWINDER_APPLE_H_
+#define BASE_PROFILER_NATIVE_UNWINDER_APPLE_H_
+
+#include <vector>
+
+#include <os/availability.h>
+
+#include "base/base_export.h"
+#include "base/profiler/unwinder.h"
+
+namespace base {
+
+// Native unwinder implementation for iOS, ARM64 and X86_64, and macOS 10.14+.
+class BASE_EXPORT API_AVAILABLE(ios(12), macosx(10.14)) NativeUnwinderApple
+    : public Unwinder {
+ public:
+  NativeUnwinderApple();
+
+  NativeUnwinderApple(const NativeUnwinderApple&) = delete;
+  NativeUnwinderApple& operator=(const NativeUnwinderApple&) = delete;
+
+  // Unwinder:
+  bool CanUnwindFrom(const Frame& current_frame) const override;
+  UnwindResult TryUnwind(RegisterContext* thread_context,
+                         uintptr_t stack_top,
+                         std::vector<Frame>* stack) const override;
+};
+
+}  // namespace base
+
+#endif  // BASE_PROFILER_NATIVE_UNWINDER_APPLE_H_