From d7c532d8894ce806c9af13b8dd3eec975642b348 Mon Sep 17 00:00:00 2001 From: comex Date: Sat, 1 Jul 2023 15:00:39 -0700 Subject: Fixes and workarounds to make UBSan happier on macOS There are still some other issues not addressed here, but it's a start. Workarounds for false-positive reports: - `RasterizerAccelerated`: Put a gigantic array behind a `unique_ptr`, because UBSan has a [hardcoded limit](https://stackoverflow.com/questions/64531383/c-runtime-error-using-fsanitize-undefined-object-has-a-possibly-invalid-vp) of how big it thinks objects can be, specifically when dealing with offset-to-top values used with multiple inheritance. Hopefully this doesn't have a performance impact. - `QueryCacheBase::QueryCacheBase`: Avoid an operation that UBSan thinks is UB even though it at least arguably isn't. See the link in the comment for more information. Fixes for correct reports: - `PageTable`, `Memory`: Use `uintptr_t` values instead of pointers to avoid UB from pointer overflow (when pointer arithmetic wraps around the address space). - `KScheduler::Reload`: `thread->GetOwnerProcess()` can be `nullptr`; avoid calling methods on it in this case. (The existing code returns a garbage reference to a field, which is then passed into `LoadWatchpointArray`, and apparently it's never used, so it's harmless in practice but still triggers UBSan.) - `KAutoObject::Close`: This function calls `this->Destroy()`, which overwrites the beginning of the object with junk (specifically a free list pointer). Then it calls `this->UnregisterWithKernel()`. UBSan complains about a type mismatch because the vtable has been overwritten, and I believe this is indeed UB. `UnregisterWithKernel` also loads `m_kernel` from the 'freed' object, which seems to be technically safe (the overwriting doesn't extend as far as that field), but seems dubious. Switch to a `static` method and load `m_kernel` in advance. --- src/video_core/query_cache.h | 4 +++- src/video_core/rasterizer_accelerated.cpp | 5 +++-- src/video_core/rasterizer_accelerated.h | 3 ++- 3 files changed, 8 insertions(+), 4 deletions(-) (limited to 'src/video_core') diff --git a/src/video_core/query_cache.h b/src/video_core/query_cache.h index 1528cc1dd..7047e2e63 100644 --- a/src/video_core/query_cache.h +++ b/src/video_core/query_cache.h @@ -103,7 +103,9 @@ public: explicit QueryCacheBase(VideoCore::RasterizerInterface& rasterizer_, Core::Memory::Memory& cpu_memory_) : rasterizer{rasterizer_}, - cpu_memory{cpu_memory_}, streams{{CounterStream{static_cast(*this), + // Use reinterpret_cast instead of static_cast as workaround for + // UBSan bug (https://github.com/llvm/llvm-project/issues/59060) + cpu_memory{cpu_memory_}, streams{{CounterStream{reinterpret_cast(*this), VideoCore::QueryType::SamplesPassed}}} { (void)slot_async_jobs.insert(); // Null value } diff --git a/src/video_core/rasterizer_accelerated.cpp b/src/video_core/rasterizer_accelerated.cpp index 4a197d65d..f200a650f 100644 --- a/src/video_core/rasterizer_accelerated.cpp +++ b/src/video_core/rasterizer_accelerated.cpp @@ -13,7 +13,8 @@ namespace VideoCore { using namespace Core::Memory; -RasterizerAccelerated::RasterizerAccelerated(Memory& cpu_memory_) : cpu_memory{cpu_memory_} {} +RasterizerAccelerated::RasterizerAccelerated(Memory& cpu_memory_) + : cached_pages(std::make_unique()), cpu_memory{cpu_memory_} {} RasterizerAccelerated::~RasterizerAccelerated() = default; @@ -26,7 +27,7 @@ void RasterizerAccelerated::UpdatePagesCachedCount(VAddr addr, u64 size, int del std::atomic_thread_fence(std::memory_order_acquire); const u64 page_end = Common::DivCeil(addr + size, YUZU_PAGESIZE); for (u64 page = addr >> YUZU_PAGEBITS; page != page_end; ++page) { - std::atomic_uint16_t& count = cached_pages.at(page >> 2).Count(page); + std::atomic_uint16_t& count = cached_pages->at(page >> 2).Count(page); if (delta > 0) { ASSERT_MSG(count.load(std::memory_order::relaxed) < UINT16_MAX, "Count may overflow!"); diff --git a/src/video_core/rasterizer_accelerated.h b/src/video_core/rasterizer_accelerated.h index 7118b8aff..e6c0ea87a 100644 --- a/src/video_core/rasterizer_accelerated.h +++ b/src/video_core/rasterizer_accelerated.h @@ -41,7 +41,8 @@ private: }; static_assert(sizeof(CacheEntry) == 8, "CacheEntry should be 8 bytes!"); - std::array cached_pages; + using CachedPages = std::array; + std::unique_ptr cached_pages; Core::Memory::Memory& cpu_memory; }; -- cgit v1.2.3