Implemented GetSample like POSIX backtrace()

src/sampler.h

 // Copyright 2013 the V8 project 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 V8_SAMPLER_H_
 #define V8_SAMPLER_H_
 
 #include "src/base/atomicops.h"
 #include "src/frames.h"
 #include "src/globals.h"
 
+#if V8_OS_POSIX && !V8_OS_CYGWIN
+
+#define USE_SIGNALS
+
+#include <errno.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sys/time.h>
+
+#if !V8_OS_QNX && !V8_OS_NACL
+#include <sys/syscall.h>  // NOLINT
+#endif
+
+#if V8_OS_MACOSX
+#include <mach/mach.h>
+// OpenBSD doesn't have <ucontext.h>. ucontext_t lives in <signal.h>
+// and is a typedef for struct sigcontext. There is no uc_mcontext.
+#elif(!V8_OS_ANDROID || defined(__BIONIC_HAVE_UCONTEXT_T)) && \
+    !V8_OS_OPENBSD && !V8_OS_NACL
+#include <ucontext.h>
+#endif
+
+#include <unistd.h>
+
+// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
+// Old versions of the C library <signal.h> didn't define the type.
+#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
+    (defined(__arm__) || defined(__aarch64__)) && \
+    !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
+#include <asm/sigcontext.h>  // NOLINT
+#endif
+
+#elif V8_OS_WIN || V8_OS_CYGWIN
+
+#include "src/base/win32-headers.h"
+
+#endif
+
+
+#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
+
+// Not all versions of Android's C library provide ucontext_t.
+// Detect this and provide custom but compatible definitions. Note that these
+// follow the GLibc naming convention to access register values from
+// mcontext_t.
+//
+// See http://code.google.com/p/android/issues/detail?id=34784
+
+#if defined(__arm__)
+
+typedef struct sigcontext mcontext_t;
+
+typedef struct ucontext {
+  uint32_t uc_flags;
+  struct ucontext* uc_link;
+  stack_t uc_stack;
+  mcontext_t uc_mcontext;
+  // Other fields are not used by V8, don't define them here.
+} ucontext_t;
+
+#elif defined(__aarch64__)
+
+typedef struct sigcontext mcontext_t;
+
+typedef struct ucontext {
+  uint64_t uc_flags;
+  struct ucontext *uc_link;
+  stack_t uc_stack;
+  mcontext_t uc_mcontext;
+  // Other fields are not used by V8, don't define them here.
+} ucontext_t;
+
+#elif defined(__mips__)
+// MIPS version of sigcontext, for Android bionic.
+typedef struct {
+  uint32_t regmask;
+  uint32_t status;
+  uint64_t pc;
+  uint64_t gregs[32];
+  uint64_t fpregs[32];
+  uint32_t acx;
+  uint32_t fpc_csr;
+  uint32_t fpc_eir;
+  uint32_t used_math;
+  uint32_t dsp;
+  uint64_t mdhi;
+  uint64_t mdlo;
+  uint32_t hi1;
+  uint32_t lo1;
+  uint32_t hi2;
+  uint32_t lo2;
+  uint32_t hi3;
+  uint32_t lo3;
+} mcontext_t;
+
+typedef struct ucontext {
+  uint32_t uc_flags;
+  struct ucontext* uc_link;
+  stack_t uc_stack;
+  mcontext_t uc_mcontext;
+  // Other fields are not used by V8, don't define them here.
+} ucontext_t;
+
+#elif defined(__i386__)
+// x86 version for Android.
+typedef struct {
+  uint32_t gregs[19];
+  void* fpregs;
+  uint32_t oldmask;
+  uint32_t cr2;
+} mcontext_t;
+
+typedef uint32_t kernel_sigset_t[2];  // x86 kernel uses 64-bit signal masks
+typedef struct ucontext {
+  uint32_t uc_flags;
+  struct ucontext* uc_link;
+  stack_t uc_stack;
+  mcontext_t uc_mcontext;
+  // Other fields are not used by V8, don't define them here.
+} ucontext_t;
+enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };
+
+#elif defined(__x86_64__)
+// x64 version for Android.
+typedef struct {
+  uint64_t gregs[23];
+  void* fpregs;
+  uint64_t __reserved1[8];
+} mcontext_t;
+
+typedef struct ucontext {
+  uint64_t uc_flags;
+  struct ucontext *uc_link;
+  stack_t uc_stack;
+  mcontext_t uc_mcontext;
+  // Other fields are not used by V8, don't define them here.
+} ucontext_t;
+enum { REG_RBP = 10, REG_RSP = 15, REG_RIP = 16 };
+#endif
+
+#endif  // V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
+
+
 namespace v8 {
 namespace internal {
 
 class Isolate;
 
 // ----------------------------------------------------------------------------
 // Sampler
 //
 // A sampler periodically samples the state of the VM and optionally
 // (if used for profiling) the program counter and stack pointer for
 // the thread that created it.
 
-struct RegisterState {
-  RegisterState() : pc(NULL), sp(NULL), fp(NULL) {}
-  Address pc;      // Instruction pointer.
-  Address sp;      // Stack pointer.
-  Address fp;      // Frame pointer.
-};
-
 // TickSample captures the information collected for each sample.
 struct TickSample {
   TickSample()
       : state(OTHER),
         pc(NULL),
         external_callback(NULL),
         frames_count(0),
         has_external_callback(false),
         top_frame_type(StackFrame::NONE) {}
-  void Init(Isolate* isolate, const RegisterState& state);
+  void Init(Isolate* isolate, const v8::RegisterState& state);
   StateTag state;  // The state of the VM.
   Address pc;      // Instruction pointer.
   union {
     Address tos;   // Top stack value (*sp).
     Address external_callback;
   };
   static const unsigned kMaxFramesCountLog2 = 8;
   static const unsigned kMaxFramesCount = (1 << kMaxFramesCountLog2) - 1;
   Address stack[kMaxFramesCount];  // Call stack.
   base::TimeTicks timestamp;
   unsigned frames_count : kMaxFramesCountLog2;  // Number of captured frames.
   bool has_external_callback : 1;
   StackFrame::Type top_frame_type : 4;
 };
 
 class Sampler {
  public:
   // Initializes the Sampler support. Called once at VM startup.
   static void SetUp();
   static void TearDown();
 
   // Initialize sampler.
   Sampler(Isolate* isolate, int interval);
   virtual ~Sampler();
 
   Isolate* isolate() const { return isolate_; }
   int interval() const { return interval_; }
 
   // Performs stack sampling.
-  void SampleStack(const RegisterState& regs);
+  void SampleStack(const v8::RegisterState& regs);
 
   // Start and stop sampler.
   void Start();
   void Stop();
 
   // Whether the sampling thread should use this Sampler for CPU profiling?
   bool IsProfiling() const {
     return base::NoBarrier_Load(&profiling_) > 0 &&
         !base::NoBarrier_Load(&has_processing_thread_);
   }
   void IncreaseProfilingDepth();
   void DecreaseProfilingDepth();
 
   // Whether the sampler is running (that is, consumes resources).
   bool IsActive() const { return base::NoBarrier_Load(&active_); }
 
   void DoSample();
+
+  static int GetSample(Isolate* isolate,
+                       const v8::RegisterState& state,
+                       void** buffer,
+                       unsigned int depth);
+
   // If true next sample must be initiated on the profiler event processor
   // thread right after latest sample is processed.
   void SetHasProcessingThread(bool value) {
     base::NoBarrier_Store(&has_processing_thread_, value);
   }
 
   // Used in tests to make sure that stack sampling is performed.
   unsigned js_and_external_sample_count() const {
     return js_and_external_sample_count_;
   }
@@ skipping 22 matching lines @@
   bool is_counting_samples_;
   // Counts stack samples taken in JS VM state.
   unsigned js_and_external_sample_count_;
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SAMPLER_H_