Refactor and cleanup VirtualMemory.

src/platform/virtual-memory.cc

Index: src/platform/virtual-memory.cc
diff --git a/src/platform/virtual-memory.cc b/src/platform/virtual-memory.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b5f6d2d06a36351dde87db09615c1f2120af4a2b
--- /dev/null
+++ b/src/platform/virtual-memory.cc
@@ -0,0 +1,510 @@
+// Copyright 2013 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.
+
+#include "platform/virtual-memory.h"
+
+#if V8_OS_POSIX
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+
+#include <unistd.h>
+#endif
+
+#if V8_OS_MACOSX
+#include <mach/vm_statistics.h>
+#endif
+
+#include <cerrno>
+
+#include "platform/mutex.h"
+#include "utils.h"
+#include "utils/random-number-generator.h"
+#if V8_OS_CYGIN || V8_OS_WIN
+#include "win32-headers.h"
+#endif
+
+namespace v8 {
+namespace internal {
+
+class RandomAddressGenerator V8_FINAL {
+  public:
+  V8_INLINE(uintptr_t NextAddress()) {
+    LockGuard<Mutex> lock_guard(&mutex_);
+    uintptr_t address = rng_.NextInt();
+#if V8_HOST_ARCH_64_BIT
+    address = (address << 32) + static_cast<uintptr_t>(rng_.NextInt());
+#endif
+    return address;
+  }
+
+  private:
+  Mutex mutex_;
+  RandomNumberGenerator rng_;
+};
+
+typedef LazyInstance<RandomAddressGenerator,
+                     DefaultConstructTrait<RandomAddressGenerator>,
+                     ThreadSafeInitOnceTrait>::type LazyRandomAddressGenerator;
+
+#define LAZY_RANDOM_ADDRESS_GENERATOR_INITIALIZER LAZY_INSTANCE_INITIALIZER
+
+
+static V8_INLINE(void* GenerateRandomAddress()) {
+#if V8_OS_NACL
+  // TODO(bradchen): Restore randomization once Native Client gets smarter
+  // about using mmap address hints.
+  // See http://code.google.com/p/nativeclient/issues/3341
+  return NULL;
+#else  // V8_OS_NACL
+  LazyRandomAddressGenerator random_address_generator =
+      LAZY_RANDOM_ADDRESS_GENERATOR_INITIALIZER;
+  uintptr_t address = random_address_generator.Pointer()->NextAddress();
+
+# if V8_TARGET_ARCH_X64
+#  if V8_OS_CYGWIN || V8_OS_WIN
+    // Try not to map pages into the default range that windows loads DLLs.
+    // Use a multiple of 64KiB to prevent committing unused memory.
+    address += V8_UINT64_C(0x00080000000);
+    address &= V8_UINT64_C(0x3ffffff0000);
+#  else  // V8_OS_CYGWIN || V8_OS_WIN
+    // Currently available CPUs have 48 bits of virtual addressing. Truncate
+    // the hint address to 46 bits to give the kernel a fighting chance of
+    // fulfilling our placement request.
+    address &= V8_UINT64_C(0x3ffffffff000);
+#  endif  // V8_OS_CYGWIN || V8_OS_WIN
+# else  // V8_TARGET_ARCH_X64
+#  if V8_OS_CYGWIN || V8_OS_WIN
+    // Try not to map pages into the default range that windows loads DLLs.
+    // Use a multiple of 64KiB to prevent committing unused memory.
+    address += 0x04000000;
+    address &= 0x3fff0000;
+#  elif V8_OS_SOLARIS
+    // For our Solaris/illumos mmap hint, we pick a random address in the bottom
+    // half of the top half of the address space (that is, the third quarter).
+    // Because we do not MAP_FIXED, this will be treated only as a hint -- the
+    // system will not fail to mmap() because something else happens to already
+    // be mapped at our random address. We deliberately set the hint high enough
+    // to get well above the system's break (that is, the heap); Solaris and
+    // illumos will try the hint and if that fails allocate as if there were
+    // no hint at all. The high hint prevents the break from getting hemmed in
+    // at low values, ceding half of the address space to the system heap.
+    address &= 0x3ffff000;
+    address += 0x80000000;
+#  else  // V8_OS_CYGWIN || V8_OS_WIN
+    // The range 0x20000000 - 0x60000000 is relatively unpopulated across a
+    // variety of ASLR modes (PAE kernel, NX compat mode, etc) and on Mac OS X
+    // 10.6 and 10.7.
+    address &= 0x3ffff000;
+    address += 0x20000000;
+#  endif  // V8_OS_CYGIN || V8_OS_WIN
+# endif  // V8_TARGET_ARCH_X64
+    return reinterpret_cast<void*>(address);
+#endif  // V8_OS_NACL
+}
+
+
+// static
+void* VirtualMemory::AllocateRegion(size_t size,
+                                    size_t* size_return,
+                                    Executability executability) {
+  ASSERT_LT(0, size);
+  ASSERT_NE(NULL, size_return);
+  void* address = ReserveRegion(size, &size);
+  if (address == NULL) return NULL;
+  if (!CommitRegion(address, size, executability)) {
+    bool result = ReleaseRegion(address, size);
+    ASSERT(result);
+    USE(result);
+    return NULL;
+  }
+  *size_return = size;
+  return address;
+}
+
+#if V8_OS_CYGWIN || V8_OS_WIN
+
+// static
+void* VirtualMemory::ReserveRegion(size_t size, size_t* size_return) {
+  ASSERT_LT(0, size);
+  ASSERT_NE(NULL, size_return);
+  // The minimum size that can be reserved is 64KiB, see
+  // http://msdn.microsoft.com/en-us/library/ms810627.aspx
+  if (size < 64 * KB) {
+    size = 64 * KB;
+  }
+  size = RoundUp(size, GetAllocationGranularity());
+  LPVOID address = NULL;
+  // Try and randomize the allocation address (up to three attempts).
+  for (unsigned attempts = 0; address == NULL && attempts < 3; ++attempts) {
+    address = VirtualAlloc(GenerateRandomAddress(),
+                           size,
+                           MEM_RESERVE,
+                           PAGE_NOACCESS);
+  }
+  if (address == NULL) {
+    // After three attempts give up and let the kernel find and address.

[Toon Verwaest, 2013/09/10 15:11:41]

find an address

[Benedikt Meurer, 2013/09/11 09:38:08]

Done.

+    address = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
+  }
+  if (address == NULL) {
+    return NULL;
+  }
+  ASSERT(IsAligned(reinterpret_cast<uintptr_t>(address),
+                   GetAllocationGranularity()));
+  *size_return = size;
+  return address;
+}
+
+
+// static
+void* VirtualMemory::ReserveRegion(size_t size,
+                                   size_t* size_return,
+                                   size_t alignment) {
+  ASSERT_LT(0, size);
+  ASSERT_NE(NULL, size_return);
+  ASSERT(IsAligned(alignment, GetAllocationGranularity()));
+
+  size_t reserved_size;
+  Address reserved_base = static_cast<Address>(
+      ReserveRegion(size + alignment, &reserved_size));
+  if (reserved_base == NULL) {
+    return NULL;
+  }
+  ASSERT_LE(size, reserved_size);
+  ASSERT(IsAligned(reserved_size, GetPageSize()));
+
+  // Try reducing the size by freeing and then reallocating a specific area.
+  bool result = ReleaseRegion(reserved_base, reserved_size);
+  USE(result);
+  ASSERT(result);
+  size_t aligned_size = RoundUp(size, GetPageSize());
+  Address aligned_base = static_cast<Address>(
+      VirtualAlloc(RoundUp(reserved_base, alignment),
+                   aligned_size,
+                   MEM_RESERVE,
+                   PAGE_NOACCESS));
+  if (aligned_base != NULL) {
+    ASSERT(aligned_base == RoundUp(reserved_base, alignment));
+    ASSERT(IsAligned(reinterpret_cast<uintptr_t>(aligned_base),
+                     GetAllocationGranularity()));
+    ASSERT(IsAligned(aligned_size, GetPageSize()));
+    *size_return = aligned_size;
+    return aligned_base;
+  }
+
+  // Resizing failed, just go with a bigger area.
+  return ReserveRegion(reserved_size, size_return);
+}
+
+
+// static
+bool VirtualMemory::CommitRegion(void* address,
+                                 size_t size,
+                                 Executability executability) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  DWORD protect = 0;
+  switch (executability) {
+    case NOT_EXECUTABLE:
+      protect = PAGE_READWRITE;
+      break;
+
+    case EXECUTABLE:
+      protect = PAGE_EXECUTE_READWRITE;
+      break;
+  }
+  LPVOID result = VirtualAlloc(address, size, MEM_COMMIT, protect);
+  if (result == NULL) {
+    ASSERT(GetLastError() != ERROR_INVALID_ADDRESS);
+    return false;
+  }
+  ASSERT_EQ(address, result);
+  return true;
+}
+
+
+// static
+bool VirtualMemory::UncommitRegion(void* address, size_t size) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  int result = VirtualFree(address, size, MEM_DECOMMIT);
+  if (result == 0) {
+    return false;
+  }
+  return true;
+}
+
+
+// static
+bool VirtualMemory::ProtectRegion(void* address, size_t size) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  DWORD old_protect;
+  return VirtualProtect(address, size, PAGE_EXECUTE_READ, &old_protect);
+}
+
+
+// static
+bool VirtualMemory::ReleaseRegion(void* address, size_t size) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  USE(size);
+  int result = VirtualFree(address, 0, MEM_RELEASE);
+  if (result == 0) {
+    return false;
+  }
+  return true;
+}
+
+
+// static
+size_t VirtualMemory::GetAllocationGranularity() {
+  static size_t allocation_granularity = 0;
+  if (allocation_granularity == 0) {
+    SYSTEM_INFO system_info;
+    GetSystemInfo(&system_info);
+    allocation_granularity = system_info.dwAllocationGranularity;
+    MemoryBarrier();
+  }
+  return allocation_granularity;
+}
+
+
+// static
+size_t VirtualMemory::GetLimit() {
+  return 0;
+}
+
+
+// static
+size_t VirtualMemory::GetPageSize() {
+  static size_t page_size = 0;
+  if (page_size == 0) {
+    SYSTEM_INFO system_info;
+    GetSystemInfo(&system_info);
+    page_size = system_info.dwPageSize;
+    MemoryBarrier();
+  }
+  return page_size;
+}
+
+
+#else  // V8_OS_CYGIN || V8_OS_WIN
+
+
+// Constants used for mmap.
+#if V8_OS_MACOSX
+// kMmapFd is used to pass vm_alloc flags to tag the region with the user
+// defined tag 255 This helps identify V8-allocated regions in memory analysis
+// tools like vmmap(1).
+static const int kMmapFd = VM_MAKE_TAG(255);
+#else
+static const int kMmapFd = -1;
+#endif  // V8_OS_MACOSX
+static const off_t kMmapFdOffset = 0;
+
+
+// static
+void* VirtualMemory::ReserveRegion(size_t size, size_t* size_return) {
+  ASSERT_LT(0, size);
+  ASSERT_NE(NULL, size_return);
+
+  size = RoundUp(size, GetPageSize());
+  void* address = mmap(GenerateRandomAddress(),
+                       size,
+                       PROT_NONE,
+                       MAP_ANON | MAP_NORESERVE | MAP_PRIVATE,
+                       kMmapFd,
+                       kMmapFdOffset);
+  if (address == MAP_FAILED) {
+    ASSERT_NE(EINVAL, errno);
+    return NULL;
+  }
+  *size_return = size;
+  return address;
+}
+
+
+// static
+void* VirtualMemory::ReserveRegion(size_t size,
+                                   size_t* size_return,
+                                   size_t alignment) {
+  ASSERT_LT(0, size);
+  ASSERT_NE(NULL, size_return);
+  ASSERT(IsAligned(alignment, GetPageSize()));
+
+  size_t reserved_size;
+  Address reserved_base = static_cast<Address>(
+      ReserveRegion(size + alignment, &reserved_size));
+  if (reserved_base == NULL) {
+    return NULL;
+  }
+
+  Address aligned_base = RoundUp(reserved_base, alignment);
+  ASSERT_LE(reserved_base, aligned_base);
+
+  // Unmap extra memory reserved before the aligned region.
+  if (aligned_base != reserved_base) {
+    size_t prefix_size = static_cast<size_t>(aligned_base - reserved_base);
+    bool result = ReleaseRegion(reserved_base, prefix_size);
+    ASSERT(result);
+    USE(result);
+    reserved_size -= prefix_size;
+  }
+
+  size_t aligned_size = RoundUp(size, GetPageSize());
+  ASSERT_LE(aligned_size, reserved_size);
+
+  // Unmap extra memory reserved after the aligned region.
+  if (aligned_size != reserved_size) {
+    size_t suffix_size = reserved_size - aligned_size;
+    bool result = ReleaseRegion(aligned_base + aligned_size, suffix_size);
+    ASSERT(result);
+    USE(result);
+    reserved_size -= suffix_size;
+  }
+
+  ASSERT(aligned_size == reserved_size);
+  ASSERT_NE(NULL, aligned_base);
+
+  *size_return = aligned_size;
+  return aligned_base;
+}
+
+
+// static
+bool VirtualMemory::CommitRegion(void* address,
+                                 size_t size,
+                                 Executability executability) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  int prot = 0;
+  // The Native Client port of V8 uses an interpreter,
+  // so code pages don't need PROT_EXEC.
+#if V8_OS_NACL
+  executability = NOT_EXECUTABLE;
+#endif
+  switch (executability) {
+    case NOT_EXECUTABLE:
+      prot = PROT_READ | PROT_WRITE;
+      break;
+
+    case EXECUTABLE:
+      prot = PROT_EXEC | PROT_READ | PROT_WRITE;
+      break;
+  }
+  void* result = mmap(address,
+                      size,
+                      prot,
+                      MAP_ANON | MAP_FIXED | MAP_PRIVATE,
+                      kMmapFd,
+                      kMmapFdOffset);
+  if (result == MAP_FAILED) {
+    ASSERT_NE(EINVAL, errno);
+    return false;
+  }
+  return true;
+}
+
+
+// static
+bool VirtualMemory::UncommitRegion(void* address, size_t size) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  void* result = mmap(address,
+                      size,
+                      PROT_NONE,
+                      MAP_ANON | MAP_FIXED | MAP_NORESERVE | MAP_PRIVATE,
+                      kMmapFd,
+                      kMmapFdOffset);
+  if (result == MAP_FAILED) {
+    ASSERT_NE(EINVAL, errno);
+    return false;
+  }
+  return true;
+}
+
+
+// static
+bool VirtualMemory::ProtectRegion(void* address, size_t size) {

[Toon Verwaest, 2013/09/10 15:11:41]

I'd prefer a more descriptive name here. Maybe WriteProtectRegion? And if it's
called that way, could we mask out the write-bit rather than making whatever you
call this with executable?

[Benedikt Meurer, 2013/09/11 09:38:08]

Done. I think we will replace this method with a better alternative once we can
write protect the code areas in the heap. Until then we'll stick to
WriteProtectRegion().

+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+#if V8_OS_NACL
+  // The Native Client port of V8 uses an interpreter,
+  // so code pages don't need PROT_EXEC.
+  int prot = PROT_READ;
+#else
+  int prot = PROT_EXEC | PROT_READ;
+#endif
+  int result = mprotect(address, size, prot);
+  if (result < 0) {
+    ASSERT_NE(EINVAL, errno);
+    return false;
+  }
+  return true;
+}
+
+
+// static
+bool VirtualMemory::ReleaseRegion(void* address, size_t size) {
+  ASSERT_NE(NULL, address);
+  ASSERT_LT(0, size);
+  int result = munmap(address, size);
+  if (result < 0) {
+    ASSERT_NE(EINVAL, errno);
+    return false;
+  }
+  return true;
+}
+
+
+// static
+size_t VirtualMemory::GetAllocationGranularity() {
+  return GetPageSize();
+}
+
+
+// static
+size_t VirtualMemory::GetLimit() {
+  struct rlimit rlim;
+  int result = getrlimit(RLIMIT_DATA, &rlim);
+  ASSERT_EQ(0, result);
+  USE(result);
+  return rlim.rlim_cur;
+}
+
+
+// static
+size_t VirtualMemory::GetPageSize() {
+  static const size_t kPageSize = getpagesize();
+  return kPageSize;
+}
+
+#endif  // V8_OS_CYGWIN || V8_OS_WIN
+
+} }  // namespace v8::internal