CSE2410 Fall 2014 Bounce

// Copyright 2012 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Platform specific code for OpenBSD and NetBSD goes here. For the POSIX

// comaptible parts the implementation is in platform-posix.cc.

#include <pthread.h>

#include <semaphore.h>

#include <signal.h>

#include <sys/time.h>

#include <sys/resource.h>

#include <sys/syscall.h>

#include <sys/types.h>

#include <stdlib.h>

#include <sys/types.h>  // mmap & munmap

#include <sys/mman.h>   // mmap & munmap

#include <sys/stat.h>   // open

#include <fcntl.h>      // open

#include <unistd.h>     // sysconf

#include <strings.h>    // index

#include <errno.h>

#include <stdarg.h>

#undef MAP_TYPE

#include "v8.h"

#include "platform.h"

#include "v8threads.h"

#include "vm-state-inl.h"

namespace v8 {

namespace internal {

const char* OS::LocalTimezone(double time) {

  if (std::isnan(time)) return "";

  time_t tv = static_cast<time_t>(floor(time/msPerSecond));

  struct tm* t = localtime(&tv);

  if (NULL == t) return "";

  return t->tm_zone;

}

double OS::LocalTimeOffset() {

  time_t tv = time(NULL);

  struct tm* t = localtime(&tv);

  // tm_gmtoff includes any daylight savings offset, so subtract it.

  return static_cast<double>(t->tm_gmtoff * msPerSecond -

                             (t->tm_isdst > 0 ? 3600 * msPerSecond : 0));

}

void* OS::Allocate(const size_t requested,

                   size_t* allocated,

                   bool is_executable) {

  const size_t msize = RoundUp(requested, AllocateAlignment());

  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);

  void* addr = OS::GetRandomMmapAddr();

  void* mbase = mmap(addr, msize, prot, MAP_PRIVATE | MAP_ANON, -1, 0);

  if (mbase == MAP_FAILED) {

    LOG(i::Isolate::Current(),

        StringEvent("OS::Allocate", "mmap failed"));

    return NULL;

  }

  *allocated = msize;

  return mbase;

}

class PosixMemoryMappedFile : public OS::MemoryMappedFile {

 public:

  PosixMemoryMappedFile(FILE* file, void* memory, int size)

    : file_(file), memory_(memory), size_(size) { }

  virtual ~PosixMemoryMappedFile();

  virtual void* memory() { return memory_; }

  virtual int size() { return size_; }

 private:

  FILE* file_;

  void* memory_;

  int size_;

};

OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {

  FILE* file = fopen(name, "r+");

  if (file == NULL) return NULL;

  fseek(file, 0, SEEK_END);

  int size = ftell(file);

  void* memory =

      mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);

  return new PosixMemoryMappedFile(file, memory, size);

}

OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,

    void* initial) {

  FILE* file = fopen(name, "w+");

  if (file == NULL) return NULL;

  int result = fwrite(initial, size, 1, file);

  if (result < 1) {

    fclose(file);

    return NULL;

  }

  void* memory =

      mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);

  return new PosixMemoryMappedFile(file, memory, size);

}

PosixMemoryMappedFile::~PosixMemoryMappedFile() {

  if (memory_) OS::Free(memory_, size_);

  fclose(file_);

}

void OS::LogSharedLibraryAddresses(Isolate* isolate) {

  // This function assumes that the layout of the file is as follows:

  // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]

  // If we encounter an unexpected situation we abort scanning further entries.

  FILE* fp = fopen("/proc/self/maps", "r");

  if (fp == NULL) return;

  // Allocate enough room to be able to store a full file name.

  const int kLibNameLen = FILENAME_MAX + 1;

  char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));

  // This loop will terminate once the scanning hits an EOF.

  while (true) {

    uintptr_t start, end;

    char attr_r, attr_w, attr_x, attr_p;

    // Parse the addresses and permission bits at the beginning of the line.

    if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;

    if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;

    int c;

    if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {

      // Found a read-only executable entry. Skip characters until we reach

      // the beginning of the filename or the end of the line.

      do {

        c = getc(fp);

      } while ((c != EOF) && (c != '\n') && (c != '/'));

      if (c == EOF) break;  // EOF: Was unexpected, just exit.

      // Process the filename if found.

      if (c == '/') {

        ungetc(c, fp);  // Push the '/' back into the stream to be read below.

        // Read to the end of the line. Exit if the read fails.

        if (fgets(lib_name, kLibNameLen, fp) == NULL) break;

        // Drop the newline character read by fgets. We do not need to check

        // for a zero-length string because we know that we at least read the

        // '/' character.

        lib_name[strlen(lib_name) - 1] = '\0';

      } else {

        // No library name found, just record the raw address range.

        snprintf(lib_name, kLibNameLen,

                 "%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end);

      }

      LOG(isolate, SharedLibraryEvent(lib_name, start, end));

    } else {

      // Entry not describing executable data. Skip to end of line to set up

      // reading the next entry.

      do {

        c = getc(fp);

      } while ((c != EOF) && (c != '\n'));

      if (c == EOF) break;

    }

  }

  free(lib_name);

  fclose(fp);

}

void OS::SignalCodeMovingGC() {

  // Support for ll_prof.py.

  //

  // The Linux profiler built into the kernel logs all mmap's with

  // PROT_EXEC so that analysis tools can properly attribute ticks. We

  // do a mmap with a name known by ll_prof.py and immediately munmap

  // it. This injects a GC marker into the stream of events generated

  // by the kernel and allows us to synchronize V8 code log and the

  // kernel log.

  int size = sysconf(_SC_PAGESIZE);

  FILE* f = fopen(FLAG_gc_fake_mmap, "w+");

  if (f == NULL) {

    OS::PrintError("Failed to open %s\n", FLAG_gc_fake_mmap);

    OS::Abort();

  }

  void* addr = mmap(NULL, size, PROT_READ | PROT_EXEC, MAP_PRIVATE,

                    fileno(f), 0);

  ASSERT(addr != MAP_FAILED);

  OS::Free(addr, size);

  fclose(f);

}

// Constants used for mmap.

static const int kMmapFd = -1;

static const int kMmapFdOffset = 0;

VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }

VirtualMemory::VirtualMemory(size_t size)

    : address_(ReserveRegion(size)), size_(size) { }

VirtualMemory::VirtualMemory(size_t size, size_t alignment)

    : address_(NULL), size_(0) {

  ASSERT(IsAligned(alignment, static_cast<intptr_t>(OS::AllocateAlignment())));

  size_t request_size = RoundUp(size + alignment,

                                static_cast<intptr_t>(OS::AllocateAlignment()));

  void* reservation = mmap(OS::GetRandomMmapAddr(),

                           request_size,

                           PROT_NONE,

                           MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,

                           kMmapFd,

                           kMmapFdOffset);

  if (reservation == MAP_FAILED) return;

  Address base = static_cast<Address>(reservation);

  Address aligned_base = RoundUp(base, alignment);

  ASSERT_LE(base, aligned_base);

  // Unmap extra memory reserved before and after the desired block.

  if (aligned_base != base) {

    size_t prefix_size = static_cast<size_t>(aligned_base - base);

    OS::Free(base, prefix_size);

    request_size -= prefix_size;

  }

  size_t aligned_size = RoundUp(size, OS::AllocateAlignment());

  ASSERT_LE(aligned_size, request_size);

  if (aligned_size != request_size) {

    size_t suffix_size = request_size - aligned_size;

    OS::Free(aligned_base + aligned_size, suffix_size);

    request_size -= suffix_size;

  }

  ASSERT(aligned_size == request_size);

  address_ = static_cast<void*>(aligned_base);

  size_ = aligned_size;

}

VirtualMemory::~VirtualMemory() {

  if (IsReserved()) {

    bool result = ReleaseRegion(address(), size());

    ASSERT(result);

    USE(result);

  }

}

bool VirtualMemory::IsReserved() {

  return address_ != NULL;

}

void VirtualMemory::Reset() {

  address_ = NULL;

  size_ = 0;

}

bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {

  return CommitRegion(address, size, is_executable);

}

bool VirtualMemory::Uncommit(void* address, size_t size) {

  return UncommitRegion(address, size);

}

bool VirtualMemory::Guard(void* address) {

  OS::Guard(address, OS::CommitPageSize());

  return true;

}

void* VirtualMemory::ReserveRegion(size_t size) {

  void* result = mmap(OS::GetRandomMmapAddr(),

                      size,

                      PROT_NONE,

                      MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,

                      kMmapFd,

                      kMmapFdOffset);

  if (result == MAP_FAILED) return NULL;

  return result;

}

bool VirtualMemory::CommitRegion(void* base, size_t size, bool is_executable) {

  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);

  if (MAP_FAILED == mmap(base,

                         size,

                         prot,

                         MAP_PRIVATE | MAP_ANON | MAP_FIXED,

                         kMmapFd,

                         kMmapFdOffset)) {

    return false;

  }

  return true;

}

bool VirtualMemory::UncommitRegion(void* base, size_t size) {

  return mmap(base,

              size,

              PROT_NONE,

              MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | MAP_FIXED,

              kMmapFd,

              kMmapFdOffset) != MAP_FAILED;

}

bool VirtualMemory::ReleaseRegion(void* base, size_t size) {

  return munmap(base, size) == 0;

}

bool VirtualMemory::HasLazyCommits() {

  // TODO(alph): implement for the platform.

  return false;

}

} }  // namespace v8::internal