Summary:
Objective-C employs tagged pointers, that is, small objects/values may be encoded directly in the pointer bits. The resulting pointer is not backed by an allocation/does not point to a valid memory. TSan infrastructure requires a valid address for `Acquire/Release` and `Mutex{Lock/Unlock}`.
This patch establishes such a mapping via a "dummy allocation" for each encountered tagged pointer value.
Reviewers: dcoughlin, kubamracek, dvyukov, delcypher
Reviewed By: dvyukov
Subscribers: llvm-commits, #sanitizers
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D56238
llvm-svn: 350556
Objective-C tagged pointers (either bottom-most or top-most bit is 1) are valid Obj-C objects but are not valid pointers. Make sure we don't crash on them when used in objc_sync_enter/objc_sync_exit. Instead, let's synchronize on a global object.
Differential Revision: https://reviews.llvm.org/D49707
llvm-svn: 337837
Objective-C's @synchronize synchronization primitive uses calls to objc_sync_enter and objc_sync_exit runtime functions. In most cases, they end up just calling pthread_mutex_lock/pthread_mutex_unlock, but there are some cases where the synchronization from pthread_mutex_lock/pthread_mutex_unlock interceptors isn't enough. Let's add explicit interceptors for objc_sync_enter and objc_sync_exit to handle all cases.
Differential Revision: https://reviews.llvm.org/D45487
llvm-svn: 329982
Building with a new clang produces a bunch of warnings about dropped 'const' and 'volatile' qualifiers on pointers. Let's fix them.
Differential Revision: https://reviews.llvm.org/D39861
llvm-svn: 317929
TSan reports a false positive when using xpc_connection_cancel. We're missing a happens-before edge from xpc_connection_cancel to the event handler on the same connection.
Differential Revision: https://reviews.llvm.org/D31475
llvm-svn: 299086
We already have an interceptor for __shared_weak_count::__release_shared, this patch handles __shared_count::__release_shared in the same way. This should get rid of TSan false positives when using std::future.
Differential Revision: https://reviews.llvm.org/D27797
llvm-svn: 289831
This patch adds a wrapper for call_once, which uses an already-compiled helper __call_once with an atomic release which is invisible to TSan. To avoid false positives, the interceptor performs an explicit atomic release in the callback wrapper.
Differential Revision: https://reviews.llvm.org/D24188
llvm-svn: 280920
The system implementation of OSAtomicTestAndClear returns the original bit, but the TSan interceptor has a bug which always returns zero from the function. This patch fixes this and adds a test.
Differential Revision: https://reviews.llvm.org/D23061
llvm-svn: 277461
The non-barrier versions of OSAtomic* functions are semantically mo_relaxed, but the two variants (e.g. OSAtomicAdd32 and OSAtomicAdd32Barrier) are actually aliases of each other, and we cannot have different interceptors for them, because they're actually the same function. Thus, we have to stay conservative and treat the non-barrier versions as mo_acq_rel.
Differential Revision: http://reviews.llvm.org/D21733
llvm-svn: 273890
There is a "well-known" TSan false positive when using C++ weak_ptr/shared_ptr and code in destructors, e.g. described at <https://llvm.org/bugs/show_bug.cgi?id=22324>. The "standard" solution is to build and use a TSan-instrumented version of libcxx, which is not trivial for end-users. This patch tries a different approach (on OS X): It adds an interceptor for the specific function in libc++.dylib, which implements the atomic operation that needs to be visible to TSan.
Differential Revision: http://reviews.llvm.org/D21609
llvm-svn: 273806
OS X provides atomic functions in libkern/OSAtomic.h. These provide atomic guarantees and they have alternatives which have barrier semantics. This patch adds proper TSan support for the functions from libkern/OSAtomic.h.
Differential Revision: http://reviews.llvm.org/D18500
llvm-svn: 265665
XPC APIs have async callbacks, and we need some more happen-before edges to avoid false positives. This patch add them, plus a test case (sorry for the long boilerplate code, but XPC just needs all that).
Differential Revision: http://reviews.llvm.org/D18493
llvm-svn: 265661
On OS X, there are other-than-pthread locking APIs that are used quite extensively - OSSpinLock and os_lock_lock. Let's add interceptors for those.
Differential Revision: http://reviews.llvm.org/D14987
llvm-svn: 254611
Julian Lettner