Changeset 111234 in webkit

Timestamp:

Mar 19, 2012 1:39:15 PM (12 years ago)

Author:

commit-queue@webkit.org

Message:

[BlackBerry] Implement OSAllocator::commit/decommit in the correct way
​https://bugs.webkit.org/show_bug.cgi?id=77013

We should use mmap(PROT_NONE, MAP_LAZY) instead of posix_madvise() to
implement memory decommitting for QNX.

Patch by Yong Li <​yoli@rim.com> on 2012-03-19
Reviewed by Rob Buis.

• wtf/OSAllocatorPosix.cpp:

(WTF::OSAllocator::reserveUncommitted):
(WTF::OSAllocator::commit):
(WTF::OSAllocator::decommit):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• wtf/OSAllocatorPosix.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2012-03-19  Yong Li  <yoli@rim.com>
+
+        [BlackBerry] Implement OSAllocator::commit/decommit in the correct way
+        https://bugs.webkit.org/show_bug.cgi?id=77013
+
+        We should use mmap(PROT_NONE, MAP_LAZY) instead of posix_madvise() to
+        implement memory decommitting for QNX.
+
+        Reviewed by Rob Buis.
+
+        * wtf/OSAllocatorPosix.cpp:
+        (WTF::OSAllocator::reserveUncommitted):
+        (WTF::OSAllocator::commit):
+        (WTF::OSAllocator::decommit):
+
 2012-03-19  Gavin Barraclough  <barraclough@apple.com>
 

trunk/Source/JavaScriptCore/wtf/OSAllocatorPosix.cpp

@@ -37 +37 @@
 void* OSAllocator::reserveUncommitted(size_t bytes, Usage usage, bool writable, bool executable, bool includesGuardPages)
 {
+#if OS(QNX)
+    // Reserve memory with PROT_NONE and MAP_LAZY so it isn't committed now.
+    void* result = mmap(0, bytes, PROT_NONE, MAP_LAZY | MAP_PRIVATE | MAP_ANON, -1, 0);
+    if (result == MAP_FAILED)
+        CRASH();
+#else // OS(QNX)
+
     void* result = reserveAndCommit(bytes, usage, writable, executable, includesGuardPages);
-#if OS(QNX)
-    posix_madvise(result, bytes, POSIX_MADV_DONTNEED);
-#elif OS(LINUX)
+#if OS(LINUX)
     madvise(result, bytes, MADV_DONTNEED);
 #elif HAVE(MADV_FREE_REUSE)
@@ -46 +51 @@
     while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
 #endif
+
+#endif // OS(QNX)
+
     return result;
 }
@@ -123 +131 @@
 }
 
-void OSAllocator::commit(void* address, size_t bytes, bool, bool)
+void OSAllocator::commit(void* address, size_t bytes, bool writable, bool executable)
 {
 #if OS(QNX)
-    posix_madvise(address, bytes, POSIX_MADV_WILLNEED);
+    int protection = PROT_READ;
+    if (writable)
+        protection |= PROT_WRITE;
+    if (executable)
+        protection |= PROT_EXEC;
+    if (MAP_FAILED == mmap(address, bytes, protection, MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0))
+        CRASH();
 #elif OS(LINUX)
+    UNUSED_PARAM(writable);
+    UNUSED_PARAM(executable);
     madvise(address, bytes, MADV_WILLNEED);
 #elif HAVE(MADV_FREE_REUSE)
+    UNUSED_PARAM(writable);
+    UNUSED_PARAM(executable);
     while (madvise(address, bytes, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { }
 #else
@@ -135 +153 @@
     UNUSED_PARAM(address);
     UNUSED_PARAM(bytes);
+    UNUSED_PARAM(writable);
+    UNUSED_PARAM(executable);
 #endif
 }
@@ -141 +161 @@
 {
 #if OS(QNX)
-    posix_madvise(address, bytes, POSIX_MADV_DONTNEED);
+    // Use PROT_NONE and MAP_LAZY to decommit the pages.
+    mmap(address, bytes, PROT_NONE, MAP_FIXED | MAP_LAZY | MAP_PRIVATE | MAP_ANON, -1, 0);
 #elif OS(LINUX)
     madvise(address, bytes, MADV_DONTNEED);