AuroraMiddleware/v8
1
0
Fork 0
Code Issues 2 Pull Requests Releases Wiki Activity

[wasm] Reset thread-in-wasm flag in C functions

Browse Source 
On Windows in an asan build we have to reset the thread-in-wasm flag in
the memory_init_wrapper, memory_copy_wrapper, and memory_fill_wrapper.
Accidentally I removed this code for the memory_init_wrapper and the
memory_copy_wrapper recently. This CL introduces the code again.

R=clemensb@chromium.org

Bug: v8:10281
Change-Id: If46def5cd64ac8cbff9b86108189462717961edd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2098737
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66686}
This commit is contained in:
Andreas Haas 2020-03-12 14:54:49 +01:00 committed by Commit Bot
parent 402b7f15a4
commit 4253a00ec8
1 changed files with 40 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
src/wasm/wasm-external-refs.cc
View File

@ -325,9 +325,47 @@ void float64_pow_wrapper(Address data) {
WriteUnalignedValue<double>(data, base::ieee754::pow(x, y));
}
namespace {
class ThreadNotInWasmScope {
// Asan on Windows triggers exceptions to allocate shadow memory lazily. When
// this function is called from WebAssembly, these exceptions would be handled
// by the trap handler before they get handled by Asan, and thereby confuse the
// thread-in-wasm flag. Therefore we disable ASAN for this function.
// Alternatively we could reset the thread-in-wasm flag before calling this
// function. However, as this is only a problem with Asan on Windows, we did not
// consider it worth the overhead.
#if defined(RESET_THREAD_IN_WASM_FLAG_FOR_ASAN_ON_WINDOWS)
public:
ThreadNotInWasmScope() : thread_was_in_wasm_(trap_handler::IsThreadInWasm()) {
if (thread_was_in_wasm_) {
trap_handler::ClearThreadInWasm();
}
}
~ThreadNotInWasmScope() {
if (thread_was_in_wasm_) {
trap_handler::SetThreadInWasm();
}
}
private:
bool thread_was_in_wasm_;
#else
public:
ThreadNotInWasmScope() {
// This is needed to avoid compilation errors (unused variable).
USE(this);
}
#endif
};
} // namespace
int32_t memory_init_wrapper(Address data) {
constexpr int32_t kSuccess = 1;
constexpr int32_t kOutOfBounds = 0;
ThreadNotInWasmScope thread_not_in_wasm_scope;
DisallowHeapAllocation disallow_heap_allocation;
size_t offset = 0;
Object raw_instance = ReadUnalignedValue<Object>(data);
@ -357,6 +395,7 @@ int32_t memory_init_wrapper(Address data) {
int32_t memory_copy_wrapper(Address data) {
constexpr int32_t kSuccess = 1;
constexpr int32_t kOutOfBounds = 0;
ThreadNotInWasmScope thread_not_in_wasm_scope;
DisallowHeapAllocation disallow_heap_allocation;
size_t offset = 0;
Object raw_instance = ReadUnalignedValue<Object>(data);
@ -378,17 +417,8 @@ int32_t memory_copy_wrapper(Address data) {
return kSuccess;
}
// Asan on Windows triggers exceptions in this function that confuse the
// WebAssembly trap handler, so Asan is disabled. See the comment on
// memory_copy_wrapper above for more info.
void memory_fill_wrapper(Address dst, uint32_t value, uint32_t size) {
#if defined(RESET_THREAD_IN_WASM_FLAG_FOR_ASAN_ON_WINDOWS)
bool thread_was_in_wasm = trap_handler::IsThreadInWasm();
if (thread_was_in_wasm) {
trap_handler::ClearThreadInWasm();
}
#endif
ThreadNotInWasmScope thread_not_in_wasm_scope;
// Use an explicit forward copy to match the required semantics for the
// memory.fill instruction. It is assumed that the caller of this function
// has already performed bounds checks, so {dst + size} should not overflow.
@ -398,11 +428,6 @@ void memory_fill_wrapper(Address dst, uint32_t value, uint32_t size) {
for (; size > 0; size--) {
*dst8++ = value8;
}
#if defined(RESET_THREAD_IN_WASM_FLAG_FOR_ASAN_ON_WINDOWS)
if (thread_was_in_wasm) {
trap_handler::SetThreadInWasm();
}
#endif
}
static WasmTrapCallbackForTesting wasm_trap_callback_for_testing = nullptr;