Index: base/allocator/allocator_shim.cc |
diff --git a/base/allocator/allocator_shim.cc b/base/allocator/allocator_shim.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..cc5097ec543cd589afc7e306b6963481b46be2ba |
--- /dev/null |
+++ b/base/allocator/allocator_shim.cc |
@@ -0,0 +1,246 @@ |
+// Copyright 2016 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "base/allocator/allocator_shim.h" |
+ |
+#include <errno.h> |
+#include <unistd.h> |
+ |
+#include <new> |
+ |
+#include "base/atomicops.h" |
+#include "base/logging.h" |
+#include "base/macros.h" |
+#include "base/threading/platform_thread.h" |
+#include "build/build_config.h" |
+ |
+// No calls to malloc / new in this file. They would would cause re-entrancy of |
+// the shim, which is hard to deal with. Keep this code as simple as possible |
+// and don't use any external C++ object here, not even //base ones. Even if |
+// they are safe to use today, in future they might be refactored. |
+ |
+namespace { |
+ |
+using namespace base; |
+ |
+subtle::AtomicWord g_chain_head = reinterpret_cast<subtle::AtomicWord>( |
+ &allocator::AllocatorDispatch::default_dispatch); |
+ |
+bool g_call_new_handler_on_malloc_failure = false; |
+subtle::Atomic32 g_new_handler_lock = 0; |
+ |
+// In theory this should be just base::ThreadChecker. But we can't afford |
+// the luxury of a LazyInstance<ThreadChecker> here as it would cause a new(). |
+bool CalledOnValidThread() { |
+ using subtle::Atomic32; |
+ const Atomic32 kInvalidTID = static_cast<Atomic32>(kInvalidThreadId); |
+ static Atomic32 g_tid = kInvalidTID; |
+ Atomic32 cur_tid = static_cast<Atomic32>(PlatformThread::CurrentId()); |
+ Atomic32 prev_tid = |
+ subtle::NoBarrier_CompareAndSwap(&g_tid, kInvalidTID, cur_tid); |
+ return prev_tid == kInvalidTID || prev_tid == cur_tid; |
+} |
+ |
+inline size_t GetPageSize() { |
+ static size_t pagesize = 0; |
+ if (!pagesize) |
+ pagesize = sysconf(_SC_PAGESIZE); |
+ return pagesize; |
+} |
+ |
+// Calls the std::new handler thread-safely. Returns true if a new_handler was |
+// set and called, false if no new_handler was set. |
+bool CallNewHandler() { |
+ // TODO(primiano): C++11 has introduced ::get_new_handler() which is supposed |
+ // to be thread safe and would avoid the spinlock boilerplate here. However |
+ // it doesn't seem to be available yet in the Linux chroot headers yet. |
+ std::new_handler nh; |
+ { |
+ while (subtle::Acquire_CompareAndSwap(&g_new_handler_lock, 0, 1)) |
+ PlatformThread::YieldCurrentThread(); |
+ nh = std::set_new_handler(0); |
+ ignore_result(std::set_new_handler(nh)); |
+ subtle::Release_Store(&g_new_handler_lock, 0); |
+ } |
+ if (!nh) |
+ return false; |
+ (*nh)(); |
+ // Assume the new_handler will abort if it fails. Exception are disabled and |
+ // we don't support the case of a new_handler throwing std::bad_balloc. |
+ return true; |
+} |
+ |
+inline const allocator::AllocatorDispatch* GetChainHead() { |
+ return reinterpret_cast<const allocator::AllocatorDispatch*>( |
+ subtle::NoBarrier_Load(&g_chain_head)); |
+} |
+ |
+} // namespace |
+ |
+namespace base { |
+namespace allocator { |
+ |
+void SetCallNewHandlerOnMallocFailure(bool value) { |
+ g_call_new_handler_on_malloc_failure = value; |
+} |
+ |
+void* UncheckedAlloc(size_t size) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ return chain_head->alloc_function(chain_head, size); |
+} |
+ |
+void InsertAllocatorDispatch(AllocatorDispatch* dispatch) { |
+ // Ensure this is always called on the same thread. |
+ DCHECK(CalledOnValidThread()); |
+ |
+ dispatch->next = GetChainHead(); |
+ |
+ // This function does not guarantee to be thread-safe w.r.t. concurrent |
+ // insertions, but still has to guarantee that all the threads always |
+ // see a consistent chain, hence the MemoryBarrier() below. |
+ // InsertAllocatorDispatch() is NOT a fastpath, as opposite to malloc(), so |
+ // we don't really want this to be a release-store with a corresponding |
+ // acquire-load during malloc(). |
+ subtle::MemoryBarrier(); |
+ |
+ subtle::NoBarrier_Store(&g_chain_head, |
+ reinterpret_cast<subtle::AtomicWord>(dispatch)); |
+} |
+ |
+void RemoveAllocatorDispatchForTesting(AllocatorDispatch* dispatch) { |
+ DCHECK(CalledOnValidThread()); |
+ DCHECK_EQ(GetChainHead(), dispatch); |
+ subtle::NoBarrier_Store(&g_chain_head, |
+ reinterpret_cast<subtle::AtomicWord>(dispatch->next)); |
+} |
+ |
+} // namespace allocator |
+} // namespace base |
+ |
+// The Shim* functions below are the entry-points into the shim-layer and |
+// are supposed to be invoked / aliased by the allocator_shim_override_* |
+// headers to route the malloc / new symbols through the shim layer. |
+extern "C" { |
+ |
+// The general pattern for allocations is: |
+// - Try to allocate, if succeded return the pointer. |
+// - If the allocation failed: |
+// - Call the std::new_handler if it was a C++ allocation. |
+// - Call the std::new_handler if it was a malloc() (or calloc() or similar) |
+// AND SetCallNewHandlerOnMallocFailure(true). |
+// - If the std::new_handler is NOT set just return nullptr. |
+// - If the std::new_handler is set: |
+// - Assume it will abort() if it fails (very likely the new_handler will |
+// just suicide priting a message). |
+// - Assume it did succeed if it returns, in which case reattempt the alloc. |
+ |
+void* ShimCppNew(size_t size) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ void* ptr; |
+ do { |
+ ptr = chain_head->alloc_function(chain_head, size); |
+ } while (!ptr && CallNewHandler()); |
+ return ptr; |
+} |
+ |
+void ShimCppDelete(void* address) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ return chain_head->free_function(chain_head, address); |
+} |
+ |
+void* ShimMalloc(size_t size) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ void* ptr; |
+ do { |
+ ptr = chain_head->alloc_function(chain_head, size); |
+ } while (!ptr && g_call_new_handler_on_malloc_failure && CallNewHandler()); |
+ return ptr; |
+} |
+ |
+void* ShimCalloc(size_t n, size_t size) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ void* ptr; |
+ do { |
+ ptr = chain_head->alloc_zero_initialized_function(chain_head, n, size); |
+ } while (!ptr && g_call_new_handler_on_malloc_failure && CallNewHandler()); |
+ return ptr; |
+} |
+ |
+void* ShimRealloc(void* address, size_t size) { |
+ // realloc(size == 0) means free() and might return a nullptr. We should |
+ // not call the std::new_handler in that case, though. |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ void* ptr; |
+ do { |
+ ptr = chain_head->realloc_function(chain_head, address, size); |
+ } while (!ptr && size && g_call_new_handler_on_malloc_failure && |
+ CallNewHandler()); |
+ return ptr; |
+} |
+ |
+void* ShimMemalign(size_t alignment, size_t size) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ void* ptr; |
+ do { |
+ ptr = chain_head->alloc_aligned_function(chain_head, alignment, size); |
+ } while (!ptr && g_call_new_handler_on_malloc_failure && CallNewHandler()); |
+ return ptr; |
+} |
+ |
+int ShimPosixMemalign(void** res, size_t alignment, size_t size) { |
+ // posix_memalign is supposed to check the arguments. See tc_posix_memalign() |
+ // in tc_malloc.cc. |
+ if (((alignment % sizeof(void*)) != 0) || |
+ ((alignment & (alignment - 1)) != 0) || (alignment == 0)) { |
+ return EINVAL; |
+ } |
+ void* ptr = ShimMemalign(alignment, size); |
+ *res = ptr; |
+ return ptr ? 0 : ENOMEM; |
+} |
+ |
+void* ShimValloc(size_t size) { |
+ return ShimMemalign(GetPageSize(), size); |
+} |
+ |
+void* ShimPvalloc(size_t size) { |
+ // pvalloc(0) should allocate one page, according to its man page. |
+ if (size == 0) { |
+ size = GetPageSize(); |
+ } else { |
+ size = (size + GetPageSize() - 1) & ~(GetPageSize() - 1); |
+ } |
+ return ShimMemalign(GetPageSize(), size); |
+} |
+ |
+void ShimFree(void* address) { |
+ const allocator::AllocatorDispatch* const chain_head = GetChainHead(); |
+ return chain_head->free_function(chain_head, address); |
+} |
+ |
+} // extern "C" |
+ |
+// Cpp symbols (new / delete) should always be routed through the shim layer. |
+#include "base/allocator/allocator_shim_override_cpp_symbols.h" |
+ |
+// Ditto for plain malloc() / calloc() / free() etc. symbols. |
+#include "base/allocator/allocator_shim_override_libc_symbols.h" |
+ |
+// In the case of tcmalloc we also want to plumb into the glibc hooks |
+// to avoid that allocations made in glibc itself (e.g., strdup()) get |
+// accidentally performed on the glibc heap instead of the tcmalloc one. |
+#if defined(USE_TCMALLOC) |
+#include "base/allocator/allocator_shim_override_glibc_weak_symbols.h" |
+#endif |
+ |
+// Cross-checks. |
+ |
+#if defined(MEMORY_TOOL_REPLACES_ALLOCATOR) |
+#error The allocator shim should not be compiled when building for memory tools. |
+#endif |
+ |
+#if (defined(__GNUC__) && defined(__EXCEPTIONS)) || \ |
+ (defined(_HAS_EXCEPTIONS) && _HAS_EXCEPTIONS) |
+#error This code cannot be used when exceptions are turned on. |
+#endif |