src/platform-openbsd.cc - v8/v8.git - Git at Google

 // 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 <execinfo.h>   // backtrace, backtrace_symbols
 #include <strings.h>    // index
 #include <errno.h>
 #include <stdarg.h>

 #undef MAP_TYPE

 #include "v8.h"

 #include "platform-posix.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;
 }


 void OS::DumpBacktrace() {
   // Currently unsupported.
 }


 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
	// 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 <execinfo.h> // backtrace, backtrace_symbols
	#include <strings.h> // index
	#include <errno.h>
	#include <stdarg.h>

	#undef MAP_TYPE

	#include "v8.h"

	#include "platform-posix.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;
	}


	void OS::DumpBacktrace() {
	// Currently unsupported.
	}


	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