[Android] Introduce libheap_profiler for memory profiling.

tools/android/heap_profiler/heap_profiler_hooks_android.c

+// Copyright 2014 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 <dlfcn.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <unwind.h>
+
+#include "tools/android/heap_profiler/heap_profiler.h"
+
+#define HEAP_PROFILER_EXPORT __attribute__((visibility("default")))
+
+
+static inline __attribute__((always_inline))
+uint32_t get_backtrace(uintptr_t* frames, uint32_t max_depth);
+
+// Function pointers typedefs for the hooked symbols.
+typedef void* (*mmap_t)(void*, size_t, int, int, int, off_t);
+typedef void* (*mmap2_t)(void*, size_t, int, int, int, off_t);
+typedef void* (*mmap64_t)(void*, size_t, int, int, int, off64_t);
+typedef void* (*mremap_t)(void*, size_t, size_t, unsigned long);
+typedef int (*munmap_t)(void*, size_t);
+typedef void* (*malloc_t)(size_t);
+typedef void* (*calloc_t)(size_t, size_t);
+typedef void* (*realloc_t)(void*, size_t);
+typedef void (*free_t)(void*);
+
+// And their actual definitions.
+static mmap_t real_mmap;
+static mmap2_t real_mmap2;
+static mmap64_t real_mmap64;
+static mremap_t real_mremap;
+static munmap_t real_munmap;
+static malloc_t real_malloc;
+static calloc_t real_calloc;
+static realloc_t real_realloc;
+static free_t real_free;
+static int* has_forked_off_zygote;
+
+HEAP_PROFILER_EXPORT const HeapStats* heap_profiler_stats_for_tests;
+
+// +---------------------------------------------------------------------------+
+// + Initialization of heap_profiler and lookup of hooks' addresses            +
+// +---------------------------------------------------------------------------+
+__attribute__((constructor))
+static void initialize() {
+  real_mmap = (mmap_t) dlsym(RTLD_NEXT, "mmap");
+  real_mmap2 = (mmap_t) dlsym(RTLD_NEXT, "mmap2");
+  real_mmap64 = (mmap64_t) dlsym(RTLD_NEXT, "mmap64");
+  real_mremap = (mremap_t) dlsym(RTLD_NEXT, "mremap");
+  real_munmap = (munmap_t) dlsym(RTLD_NEXT, "munmap");
+  real_malloc = (malloc_t) dlsym(RTLD_NEXT, "malloc");
+  real_calloc = (calloc_t) dlsym(RTLD_NEXT, "calloc");
+  real_realloc = (realloc_t) dlsym(RTLD_NEXT, "realloc");
+  real_free = (free_t) dlsym(RTLD_NEXT, "free");
+
+  // gMallocLeakZygoteChild is an extra useful piece of information to have.
+  // When available, it tells whether we're in the zygote (=0) or forked (=1)
+  // a child off it. In the worst case it will be NULL and we'll just ignore it.
+  has_forked_off_zygote = (int*) dlsym(RTLD_NEXT, "gMallocLeakZygoteChild");
+
+  // Allocate room for the HeapStats area and initialize the heap profiler.
+  // Make an explicit map of /dev/zero (instead of MAP_ANONYMOUS), so that the
+  // heap_dump tool can easily spot the mapping in the target process.
+  int fd = open("/dev/zero", O_RDONLY);
+  if (fd < 0) {
+    abort();  // This world has gone wrong. Good night Vienna.
+  }
+
+  HeapStats* stats = (HeapStats*) real_mmap(
+      0, sizeof(HeapStats), PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+  heap_profiler_stats_for_tests = stats;
+  heap_profiler_init(stats);
+}
+
+static inline __attribute__((always_inline)) void unwind_and_record_alloc(
+    void* start, size_t size, uint32_t flags) {
+  const int errno_save = errno;
+  uintptr_t frames[HEAP_PROFILER_MAX_DEPTH];
+  const uint32_t depth = get_backtrace(frames, HEAP_PROFILER_MAX_DEPTH);
+  if (has_forked_off_zygote != NULL && *has_forked_off_zygote == 0)
+    flags |= HEAP_PROFILER_FLAGS_IN_ZYGOTE;
+  heap_profiler_alloc(start, size, frames, depth, flags);
+  errno = errno_save;
+}
+
+static inline __attribute__((always_inline)) void discard_alloc(
+    void* start, size_t size, uint32_t* old_flags) {
+  const int errno_save = errno;
+  heap_profiler_free(start, size, old_flags);
+  errno = errno_save;
+}
+
+// Flags are non-functional extra decorators that are made available to the
+// final heap_dump tool, to get more details about the source of the allocation.
+static uint32_t get_flags_for_mmap(int fd) {
+  return HEAP_PROFILER_FLAGS_MMAP | (fd ? HEAP_PROFILER_FLAGS_MMAP_FILE : 0);
+}
+
+// +---------------------------------------------------------------------------+
+// + Actual mmap/malloc hooks                                                  +
+// +---------------------------------------------------------------------------+
+HEAP_PROFILER_EXPORT void* mmap(
+    void* addr, size_t size, int prot, int flags, int fd, off_t offset)  {
+  void* ret = real_mmap(addr, size, prot, flags, fd, offset);
+  if (ret != MAP_FAILED)
+    unwind_and_record_alloc(ret, size, get_flags_for_mmap(fd));
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void* mmap2(
+    void* addr, size_t size, int prot, int flags, int fd, off_t pgoffset)  {
+  void* ret = real_mmap2(addr, size, prot, flags, fd, pgoffset);
+  if (ret != MAP_FAILED)
+    unwind_and_record_alloc(ret, size, get_flags_for_mmap(fd));
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void* mmap64(
+    void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
+  void* ret = real_mmap64(addr, size, prot, flags, fd, offset);
+  if (ret != MAP_FAILED)
+    unwind_and_record_alloc(ret, size, get_flags_for_mmap(fd));
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void* mremap(
+    void* addr, size_t oldlen, size_t newlen, unsigned long flags) {
+  void* ret = real_mremap(addr, oldlen, newlen, flags);
+  if (ret != MAP_FAILED) {
+    uint32_t flags = 0;
+    if (addr)
+      discard_alloc(addr, oldlen, &flags);
+    if (newlen > 0)
+      unwind_and_record_alloc(ret, newlen, flags);
+  }
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT int munmap(void* ptr, size_t size) {
+  int ret = real_munmap(ptr, size);
+  discard_alloc(ptr, size, /*old_flags=*/NULL);
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void* malloc(size_t byte_count) {
+  void* ret = real_malloc(byte_count);
+  if (ret != NULL)
+    unwind_and_record_alloc(ret, byte_count, HEAP_PROFILER_FLAGS_MALLOC);
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void* calloc(size_t nmemb, size_t size) {
+  void* ret = real_calloc(nmemb, size);
+  if (ret != NULL)
+    unwind_and_record_alloc(ret, nmemb * size, HEAP_PROFILER_FLAGS_MALLOC);
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void* realloc(void* ptr, size_t size) {
+  void* ret = real_realloc(ptr, size);
+  uint32_t flags = 0;
+  if (ptr)
+    discard_alloc(ptr, 0, &flags);
+  if (ret != NULL)
+    unwind_and_record_alloc(ret, size, flags | HEAP_PROFILER_FLAGS_MALLOC);
+  return ret;
+}
+
+HEAP_PROFILER_EXPORT void free(void* ptr) {
+  real_free(ptr);
+  discard_alloc(ptr, 0, /*old_flags=*/NULL);
+}
+
+// +---------------------------------------------------------------------------+
+// + Stack unwinder                                                            +
+// +---------------------------------------------------------------------------+
+typedef struct {
+  uintptr_t* frames;
+  uint32_t frame_count;
+  uint32_t max_depth;
+  bool have_skipped_self;
+} stack_crawl_state_t;
+
+static _Unwind_Reason_Code unwind_fn(struct _Unwind_Context* ctx, void* arg) {
+  stack_crawl_state_t* state = (stack_crawl_state_t*) arg;
+  uintptr_t ip = _Unwind_GetIP(ctx);
+
+  if (ip != 0 && !state->have_skipped_self) {
+    state->have_skipped_self = true;
+    return _URC_NO_REASON;
+  }
+
+  state->frames[state->frame_count++] = ip;
+  return (state->frame_count >= state->max_depth) ?
+          _URC_END_OF_STACK : _URC_NO_REASON;
+}
+
+static uint32_t get_backtrace(uintptr_t* frames, uint32_t max_depth) {
+  stack_crawl_state_t state = {.frames = frames, .max_depth = max_depth};
+  _Unwind_Backtrace(unwind_fn, &state);
+  return state.frame_count;
+}