diff options
Diffstat (limited to 'JavaScriptCore/jit/ExecutableAllocatorFixedVMPool.cpp')
| -rw-r--r-- | JavaScriptCore/jit/ExecutableAllocatorFixedVMPool.cpp | 37 |
1 files changed, 13 insertions, 24 deletions
diff --git a/JavaScriptCore/jit/ExecutableAllocatorFixedVMPool.cpp b/JavaScriptCore/jit/ExecutableAllocatorFixedVMPool.cpp index 15247c2..e280b2d 100644 --- a/JavaScriptCore/jit/ExecutableAllocatorFixedVMPool.cpp +++ b/JavaScriptCore/jit/ExecutableAllocatorFixedVMPool.cpp @@ -48,9 +48,6 @@ #define COALESCE_LIMIT (4u * 1024u * 1024u) // 4Mb #endif -// ASLR currently only works on darwin (due to arc4random) & 64-bit (due to address space size). -#define VM_POOL_ASLR (OS(DARWIN) && CPU(X86_64)) - using namespace WTF; namespace JSC { @@ -136,8 +133,7 @@ class FixedVMPoolAllocator void reuse(void* position, size_t size) { - bool okay = m_allocation.commit(position, size); - ASSERT_UNUSED(okay, okay); + m_allocation.commit(position, size); addToCommittedByteCount(static_cast<long>(size)); } @@ -282,24 +278,7 @@ public: : m_commonSize(commonSize) , m_countFreedSinceLastCoalesce(0) { - // Cook up an address to allocate at, using the following recipe: - // 17 bits of zero, stay in userspace kids. - // 26 bits of randomness for ASLR. - // 21 bits of zero, at least stay aligned within one level of the pagetables. - // - // But! - as a temporary workaround for some plugin problems (rdar://problem/6812854), - // for now instead of 2^26 bits of ASLR lets stick with 25 bits of randomization plus - // 2^24, which should put up somewhere in the middle of userspace (in the address range - // 0x200000000000 .. 0x5fffffffffff). -#if VM_POOL_ASLR - intptr_t randomLocation = 0; - randomLocation = arc4random() & ((1 << 25) - 1); - randomLocation += (1 << 24); - randomLocation <<= 21; - m_allocation = PageReservation::reserveAt(reinterpret_cast<void*>(randomLocation), false, totalHeapSize, PageAllocation::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true); -#else - m_allocation = PageReservation::reserve(totalHeapSize, PageAllocation::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true); -#endif + m_allocation = PageReservation::reserve(totalHeapSize, OSAllocator::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true); if (!!m_allocation) m_freeList.insert(new FreeListEntry(m_allocation.base(), m_allocation.size())); @@ -452,7 +431,8 @@ void ExecutableAllocator::intializePageSize() } static FixedVMPoolAllocator* allocator = 0; - +static size_t allocatedCount = 0; + bool ExecutableAllocator::isValid() const { SpinLockHolder lock_holder(&spinlock); @@ -461,10 +441,18 @@ bool ExecutableAllocator::isValid() const return allocator->isValid(); } +bool ExecutableAllocator::underMemoryPressure() +{ + // Technically we should take the spin lock here, but we don't care if we get stale data. + // This is only really a heuristic anyway. + return allocatedCount > (VM_POOL_SIZE / 2); +} + ExecutablePool::Allocation ExecutablePool::systemAlloc(size_t size) { SpinLockHolder lock_holder(&spinlock); ASSERT(allocator); + allocatedCount += size; return allocator->alloc(size); } @@ -472,6 +460,7 @@ void ExecutablePool::systemRelease(ExecutablePool::Allocation& allocation) { SpinLockHolder lock_holder(&spinlock); ASSERT(allocator); + allocatedCount -= allocation.size(); allocator->free(allocation); } |