src/profiling/memory/wire_protocol.cc

/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "src/profiling/memory/wire_protocol.h"

#include "perfetto/base/logging.h"
#include "perfetto/ext/base/unix_socket.h"
#include "perfetto/ext/base/utils.h"
#include "src/profiling/memory/shared_ring_buffer.h"

#include <sys/socket.h>
#include <sys/types.h>

#if PERFETTO_BUILDFLAG(PERFETTO_ANDROID_BUILD)
#include <bionic/mte.h>
#else
struct ScopedDisableMTE {
  // Silence unused variable warnings in non-Android builds.
  ScopedDisableMTE() {}
};
#endif

namespace perfetto {
namespace profiling {

namespace {

template <typename T>
bool ViewAndAdvance(char** ptr, T** out, const char* end) {
  if (end - sizeof(T) < *ptr)
    return false;
  *out = reinterpret_cast<T*>(*ptr);
  *ptr += sizeof(T);
  return true;
}

// We need this to prevent crashes due to FORTIFY_SOURCE.
void UnsafeMemcpy(char* dest, const char* src, size_t n)
    __attribute__((no_sanitize("address", "hwaddress"))) {
  ScopedDisableMTE m;
  for (size_t i = 0; i < n; ++i) {
    dest[i] = src[i];
  }
}

template <typename F>
int64_t WithBuffer(SharedRingBuffer* shmem, size_t total_size, F fn) {
  SharedRingBuffer::Buffer buf;
  {
    ScopedSpinlock lock = shmem->AcquireLock(ScopedSpinlock::Mode::Try);
    if (!lock.locked()) {
      PERFETTO_DLOG("Failed to acquire spinlock.");
      errno = EAGAIN;
      return -1;
    }
    buf = shmem->BeginWrite(lock, total_size);
  }
  if (!buf) {
    PERFETTO_DLOG("Buffer overflow.");
    shmem->EndWrite(std::move(buf));
    errno = EAGAIN;
    return -1;
  }

  fn(&buf);

  auto bytes_free = buf.bytes_free;
  shmem->EndWrite(std::move(buf));
  return static_cast<int64_t>(bytes_free);
}

}  // namespace

int64_t SendWireMessage(SharedRingBuffer* shmem, const WireMessage& msg) {
  switch (msg.record_type) {
    case RecordType::Malloc: {
      size_t total_size = sizeof(msg.record_type) + sizeof(*msg.alloc_header) +
                          msg.payload_size;
      return WithBuffer(
          shmem, total_size, [msg](SharedRingBuffer::Buffer* buf) {
            memcpy(buf->data, &msg.record_type, sizeof(msg.record_type));
            memcpy(buf->data + sizeof(msg.record_type), msg.alloc_header,
                   sizeof(*msg.alloc_header));
            UnsafeMemcpy(reinterpret_cast<char*>(buf->data) +
                             sizeof(msg.record_type) +
                             sizeof(*msg.alloc_header),
                         msg.payload, msg.payload_size);
          });
    }
    case RecordType::Free: {
      constexpr size_t total_size =
          sizeof(msg.record_type) + sizeof(*msg.free_header);
      return WithBuffer(
          shmem, total_size, [msg](SharedRingBuffer::Buffer* buf) {
            memcpy(buf->data, &msg.record_type, sizeof(msg.record_type));
            memcpy(buf->data + sizeof(msg.record_type), msg.free_header,
                   sizeof(*msg.free_header));
          });
    }
    case RecordType::HeapName: {
      constexpr size_t total_size =
          sizeof(msg.record_type) + sizeof(*msg.heap_name_header);
      return WithBuffer(
          shmem, total_size, [msg](SharedRingBuffer::Buffer* buf) {
            memcpy(buf->data, &msg.record_type, sizeof(msg.record_type));
            memcpy(buf->data + sizeof(msg.record_type), msg.heap_name_header,
                   sizeof(*msg.heap_name_header));
          });
    }
  }
}

bool ReceiveWireMessage(char* buf, size_t size, WireMessage* out) {
  RecordType* record_type;
  char* end = buf + size;
  if (!ViewAndAdvance<RecordType>(&buf, &record_type, end)) {
    PERFETTO_DFATAL_OR_ELOG("Cannot read record type.");
    return false;
  }

  out->payload = nullptr;
  out->payload_size = 0;
  out->record_type = *record_type;

  if (*record_type == RecordType::Malloc) {
    if (!ViewAndAdvance<AllocMetadata>(&buf, &out->alloc_header, end)) {
      PERFETTO_DFATAL_OR_ELOG("Cannot read alloc header.");
      return false;
    }
    out->payload = buf;
    if (buf > end) {
      PERFETTO_DFATAL_OR_ELOG("Receive buffer overflowed");
      return false;
    }
    out->payload_size = static_cast<size_t>(end - buf);
  } else if (*record_type == RecordType::Free) {
    if (!ViewAndAdvance<FreeEntry>(&buf, &out->free_header, end)) {
      PERFETTO_DFATAL_OR_ELOG("Cannot read free header.");
      return false;
    }
  } else if (*record_type == RecordType::HeapName) {
    if (!ViewAndAdvance<HeapName>(&buf, &out->heap_name_header, end)) {
      PERFETTO_DFATAL_OR_ELOG("Cannot read free header.");
      return false;
    }
  } else {
    PERFETTO_DFATAL_OR_ELOG("Invalid record type.");
    return false;
  }
  return true;
}

uint64_t GetHeapSamplingInterval(const ClientConfiguration& cli_config,
                                 const char* heap_name) {
  for (uint32_t i = 0; i < cli_config.num_heaps; ++i) {
    const ClientConfigurationHeap& heap = cli_config.heaps[i];
    static_assert(sizeof(heap.name) == HEAPPROFD_HEAP_NAME_SZ,
                  "correct heap name size");
    if (strncmp(&heap.name[0], heap_name, HEAPPROFD_HEAP_NAME_SZ) == 0) {
      return heap.interval;
    }
  }
  if (cli_config.all_heaps) {
    return cli_config.default_interval;
  }
  return 0;
}

}  // namespace profiling
}  // namespace perfetto