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0784b1eefa
TSan's shadow mappings only support 30-bits of ASLR entropy on x86 Linux, and it is not practical to support the maximum of 32-bits (due to pointer compression and the overhead of shadow mappings). Instead, this patch changes TSan to re-exec without ASLR if it encounters an incompatible memory layout, as suggested by Dmitry in https://github.com/google/sanitizers/issues/1716. If ASLR is already disabled but the memory layout is still incompatible, it will abort. This patch involves a bit of refactoring, because the old code is: 1. InitializePlatformEarly() 2. InitializeAllocator() 3. InitializePlatform(): CheckAndProtect() but it may already segfault during InitializeAllocator() if the memory layout is incompatible, before we get a chance to check in CheckAndProtect(). This patch adds CheckAndProtect() during InitializePlatformEarly(), before the allocator is initialized. Naturally, it is necessary to ensure that CheckAndProtect() does *not* allow the heap regions to be occupied here, hence we generalize CheckAndProtect() to optionally check the heap regions. We keep the original behavior of CheckAndProtect() in InitializePlatform() as a last line of defense. We need to be careful not to prematurely abort if ASLR is disabled but TSan was going to re-exec for other reasons (e.g., unlimited stack size); we implement this by moving all the re-exec logic into ReExecIfNeeded().
Compiler-RT ================================ This directory and its subdirectories contain source code for the compiler support routines. Compiler-RT is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. ================================