We used to mmap C++ shadow stack as part of the trace region
before ed7f3f5bc9 ("tsan: move shadow stack into ThreadState"),
which moved the shadow stack into TLS. This started causing
timeouts and OOMs on some of our internal tests that repeatedly
create and destroy thousands of threads.
Allocate C++ shadow stack with mmap and small pages again.
This prevents the observed timeouts and OOMs.
But we now need to be more careful with interceptors that
run after thread finalization because FuncEntry/Exit and
TraceAddEvent all need the shadow stack.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D113786
This change switches tsan to the new runtime which features:
- 2x smaller shadow memory (2x of app memory)
- faster fully vectorized race detection
- small fixed-size vector clocks (512b)
- fast vectorized vector clock operations
- unlimited number of alive threads/goroutimes
Depends on D112602.
Reviewed By: melver
Differential Revision: https://reviews.llvm.org/D112603
Some of the DPrintf's currently produce -Wformat warnings if enabled.
Fix these format strings.
Reviewed By: melver
Differential Revision: https://reviews.llvm.org/D110131
We frequenty allocate sizeof(T) memory and call T ctor on that memory
(C++ new keyword effectively). Currently it's quite verbose and
usually takes 2 lines of code.
Add New<T>() helper that does it much more concisely.
Rename internal_free to Free that also sets the pointer to nullptr.
Shorter and safer.
Rename internal_alloc to Alloc, just shorter.
Reviewed By: vitalybuka, melver
Differential Revision: https://reviews.llvm.org/D107085
We used to count number of allocations/bytes based on the type
and maybe record them in heap block headers.
But that's all in the past, now it's not used for anything.
Remove the mblock type.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D106971
I don't think the stat subsystem was ever used since tsan
development in 2012. But it adds lots of code and this
effectively dead code needs to be updated if the runtime
code changes, which adds maintanance cost for no benefit.
Normal profiler usually gives enough info and that info
is more trustworthy.
Remove the stats subsystem.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D106276
Commit efd254b6362 ("tsan: fix deadlock in pthread_atfork callbacks")
fixed another deadlock related to atfork handling.
But builders with DCHECKs enabled reported failures of
pthread_atfork_deadlock2.c and pthread_atfork_deadlock3.c tests
related to the fact that we hold runtime locks on interceptor exit:
https://lab.llvm.org/buildbot/#/builders/70/builds/6727
This issue is somewhat inherent to the current approach,
we indeed execute user code (atfork callbacks) with runtime lock held.
Refactor fork handling to not run user code (atfork callbacks)
with runtime locks held. This change does this by installing
own atfork callbacks during runtime initialization.
Atfork callbacks run in LIFO order, so the expectation is that
our callbacks run last, right before the actual fork.
This way we lock runtime mutexes around fork, but not around
user callbacks.
Extend tests to also install after fork callbacks just to cover
more scenarios. Some tests also started reporting real races
that we previously suppressed.
Also extend tests to cover fork syscall support.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D101517
Commit efd254b6362 ("tsan: fix deadlock in pthread_atfork callbacks")
fixed another deadlock related to atfork handling.
But builders with DCHECKs enabled reported failures of
pthread_atfork_deadlock2.c and pthread_atfork_deadlock3.c tests
related to the fact that we hold runtime locks on interceptor exit:
https://lab.llvm.org/buildbot/#/builders/70/builds/6727
This issue is somewhat inherent to the current approach,
we indeed execute user code (atfork callbacks) with runtime lock held.
Refactor fork handling to not run user code (atfork callbacks)
with runtime locks held. This change does this by installing
own atfork callbacks during runtime initialization.
Atfork callbacks run in LIFO order, so the expectation is that
our callbacks run last, right before the actual fork.
This way we lock runtime mutexes around fork, but not around
user callbacks.
Extend tests to also install after fork callbacks just to cover
more scenarios. Some tests also started reporting real races
that we previously suppressed.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D101385
We take report/thread_registry locks around fork.
This means we cannot report any bugs in atfork handlers.
We resolved this by enabling per-thread ignores around fork.
This resolved some of the cases, but not all.
The added test triggers a race report from a signal handler
called from atfork callback, we reset per-thread ignores
around signal handlers, so we tried to report it and deadlocked.
But there are more cases: a signal handler can be called
synchronously if it's sent to itself. Or any other report
types would cause deadlocks as well: mutex misuse,
signal handler spoiling errno, etc.
Disable all reports for the duration of fork with
thr->suppress_reports and don't re-enable them around
signal handlers.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D101154
Summary:
The flag allows the user to specify a maximum allocation size that the
sanitizers will honor. Any larger allocations will return nullptr or
crash depending on allocator_may_return_null.
Reviewers: kcc, eugenis
Reviewed By: kcc, eugenis
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D69576
