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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/199936">199936</a></dd>
<dt>Author</dt> <dd>ggaren@apple.com</dd>
<dt>Date</dt> <dd>2016-04-22 16:56:53 -0700 (Fri, 22 Apr 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>bmalloc: vm allocations should plant guard pages
https://bugs.webkit.org/show_bug.cgi?id=156937
Reviewed by Michael Saboff.
* bmalloc/Object.h:
(bmalloc::Object::operator-): Added a - helper.
* bmalloc/VMAllocate.h:
(bmalloc::vmRevokePermissions): Added a helper to revoke permissions on
a VM region. We use this for guard pages.
* bmalloc/VMHeap.cpp:
(bmalloc::VMHeap::allocateSmallChunk): Add guard pages to the start and
end of the chunk.
Note that we don't guard large chunks becuase we need to be able to merge
them. Otherwise, we will run out of virtual addresses.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourcebmallocChangeLog">trunk/Source/bmalloc/ChangeLog</a></li>
<li><a href="#trunkSourcebmallocbmallocObjecth">trunk/Source/bmalloc/bmalloc/Object.h</a></li>
<li><a href="#trunkSourcebmallocbmallocVMAllocateh">trunk/Source/bmalloc/bmalloc/VMAllocate.h</a></li>
<li><a href="#trunkSourcebmallocbmallocVMHeapcpp">trunk/Source/bmalloc/bmalloc/VMHeap.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourcebmallocChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/ChangeLog (199935 => 199936)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/ChangeLog 2016-04-22 23:48:44 UTC (rev 199935)
+++ trunk/Source/bmalloc/ChangeLog 2016-04-22 23:56:53 UTC (rev 199936)
</span><span class="lines">@@ -1,5 +1,26 @@
</span><span class="cx"> 2016-04-22 Geoffrey Garen <ggaren@apple.com>
</span><span class="cx">
</span><ins>+ bmalloc: vm allocations should plant guard pages
+ https://bugs.webkit.org/show_bug.cgi?id=156937
+
+ Reviewed by Michael Saboff.
+
+ * bmalloc/Object.h:
+ (bmalloc::Object::operator-): Added a - helper.
+
+ * bmalloc/VMAllocate.h:
+ (bmalloc::vmRevokePermissions): Added a helper to revoke permissions on
+ a VM region. We use this for guard pages.
+
+ * bmalloc/VMHeap.cpp:
+ (bmalloc::VMHeap::allocateSmallChunk): Add guard pages to the start and
+ end of the chunk.
+
+ Note that we don't guard large chunks becuase we need to be able to merge
+ them. Otherwise, we will run out of virtual addresses.
+
+2016-04-22 Geoffrey Garen <ggaren@apple.com>
+
</ins><span class="cx"> bmalloc: Constify introspect function pointer table
</span><span class="cx"> https://bugs.webkit.org/show_bug.cgi?id=156936
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocObjecth"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/Object.h (199935 => 199936)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/Object.h 2016-04-22 23:48:44 UTC (rev 199935)
+++ trunk/Source/bmalloc/bmalloc/Object.h 2016-04-22 23:56:53 UTC (rev 199936)
</span><span class="lines">@@ -52,6 +52,7 @@
</span><span class="cx"> SmallPage* page();
</span><span class="cx">
</span><span class="cx"> Object operator+(size_t);
</span><ins>+ Object operator-(size_t);
</ins><span class="cx"> bool operator<=(const Object&);
</span><span class="cx">
</span><span class="cx"> private:
</span><span class="lines">@@ -64,6 +65,11 @@
</span><span class="cx"> return Object(m_chunk, m_offset + offset);
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+inline Object Object::operator-(size_t offset)
+{
+ return Object(m_chunk, m_offset - offset);
+}
+
</ins><span class="cx"> inline bool Object::operator<=(const Object& other)
</span><span class="cx"> {
</span><span class="cx"> BASSERT(m_chunk == other.m_chunk);
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocVMAllocateh"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/VMAllocate.h (199935 => 199936)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/VMAllocate.h 2016-04-22 23:48:44 UTC (rev 199935)
+++ trunk/Source/bmalloc/bmalloc/VMAllocate.h 2016-04-22 23:56:53 UTC (rev 199936)
</span><span class="lines">@@ -137,6 +137,12 @@
</span><span class="cx"> munmap(p, vmSize);
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+inline void vmRevokePermissions(void* p, size_t vmSize)
+{
+ vmValidate(p, vmSize);
+ mprotect(p, vmSize, PROT_NONE);
+}
+
</ins><span class="cx"> // Allocates vmSize bytes at a specified power-of-two alignment.
</span><span class="cx"> // Use this function to create maskable memory regions.
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocVMHeapcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/VMHeap.cpp (199935 => 199936)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/VMHeap.cpp 2016-04-22 23:48:44 UTC (rev 199935)
+++ trunk/Source/bmalloc/bmalloc/VMHeap.cpp 2016-04-22 23:56:53 UTC (rev 199936)
</span><span class="lines">@@ -75,6 +75,12 @@
</span><span class="cx"> Object begin(chunk, metadataSize);
</span><span class="cx"> Object end(chunk, chunkSize);
</span><span class="cx">
</span><ins>+ vmRevokePermissions(begin.begin(), pageSize);
+ vmRevokePermissions(end.begin() - pageSize, pageSize);
+
+ begin = begin + pageSize;
+ end = end - pageSize;
+
</ins><span class="cx"> for (Object it = begin; it + pageSize <= end; it = it + pageSize) {
</span><span class="cx"> SmallPage* page = it.page();
</span><span class="cx"> new (page) SmallPage;
</span></span></pre>
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