Revert r16648, r16641, r16638 and r16637.

src/platform-linux.cc

Index: src/platform-linux.cc
diff --git a/src/platform-linux.cc b/src/platform-linux.cc
index 8296b6c34ad3c5d5c15958a32d4454a58717b30f..b8b96025e1fae2307006f10392b1cca70ef257d7 100644
--- a/src/platform-linux.cc
+++ b/src/platform-linux.cc
@@ -137,6 +137,23 @@ double OS::LocalTimeOffset() {
 }
 
 
+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_ANONYMOUS, -1, 0);
+  if (mbase == MAP_FAILED) {
+    LOG(i::Isolate::Current(),
+        StringEvent("OS::Allocate", "mmap failed"));
+    return NULL;
+  }
+  *allocated = msize;
+  return mbase;
+}
+
+
 void OS::DumpBacktrace() {
   // backtrace is a glibc extension.
 #if defined(__GLIBC__) && !defined(__UCLIBC__)
@@ -167,16 +184,12 @@ OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
   int size = ftell(file);
 
   void* memory =
-      mmap(NULL,
+      mmap(OS::GetRandomMmapAddr(),
            size,
            PROT_READ | PROT_WRITE,
            MAP_SHARED,
            fileno(file),
            0);
-  if (memory == MAP_FAILED) {
-    fclose(file);
-    return NULL;
-  }
   return new PosixMemoryMappedFile(file, memory, size);
 }
 
@@ -191,24 +204,18 @@ OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
     return NULL;
   }
   void* memory =
-      mmap(NULL,
+      mmap(OS::GetRandomMmapAddr(),
            size,
            PROT_READ | PROT_WRITE,
            MAP_SHARED,
            fileno(file),
            0);
-  if (memory == MAP_FAILED) {
-    fclose(file);
-    return NULL;
-  }
   return new PosixMemoryMappedFile(file, memory, size);
 }
 
 
 PosixMemoryMappedFile::~PosixMemoryMappedFile() {
-  int result = munmap(memory_, size_);
-  ASSERT_EQ(0, result);
-  USE(result);
+  if (memory_) OS::Free(memory_, size_);
   fclose(file_);
 }
 
@@ -288,7 +295,7 @@ void OS::SignalCodeMovingGC() {
     OS::PrintError("Failed to open %s\n", FLAG_gc_fake_mmap);
     OS::Abort();
   }
-  void* addr = mmap(NULL,
+  void* addr = mmap(OS::GetRandomMmapAddr(),
                     size,
 #if defined(__native_client__)
                     // The Native Client port of V8 uses an interpreter,
@@ -301,9 +308,7 @@ void OS::SignalCodeMovingGC() {
                     fileno(f),
                     0);
   ASSERT(addr != MAP_FAILED);
-  int result = munmap(addr, size);
-  ASSERT_EQ(0, result);
-  USE(result);
+  OS::Free(addr, size);
   fclose(f);
 }
 
@@ -317,4 +322,147 @@ int OS::StackWalk(Vector<OS::StackFrame> frames) {
 #endif
 }
 
+
+// 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_ANONYMOUS | 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_ANONYMOUS | MAP_NORESERVE,
+                      kMmapFd,
+                      kMmapFdOffset);
+
+  if (result == MAP_FAILED) return NULL;
+
+  return result;
+}
+
+
+bool VirtualMemory::CommitRegion(void* base, size_t size, bool is_executable) {
+#if defined(__native_client__)
+  // The Native Client port of V8 uses an interpreter,
+  // so code pages don't need PROT_EXEC.
+  int prot = PROT_READ | PROT_WRITE;
+#else
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
+#endif
+  if (MAP_FAILED == mmap(base,
+                         size,
+                         prot,
+                         MAP_PRIVATE | MAP_ANONYMOUS | 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_ANONYMOUS | MAP_NORESERVE | MAP_FIXED,
+              kMmapFd,
+              kMmapFdOffset) != MAP_FAILED;
+}
+
+
+bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
+  return munmap(base, size) == 0;
+}
+
+
+bool VirtualMemory::HasLazyCommits() {
+  return true;
+}
+
 } }  // namespace v8::internal