Move some of the flags previously in Options, as well as the
UseMemoryTagging flag previously in the primary allocator, into an
atomic variable so that it can be updated while other threads are
running. Relaxed accesses are used because we only have the requirement
that the other threads see the new value eventually.
The code is set up so that the variable is generally loaded once per
allocation function call with the exception of some rarely used code
such as error handlers. The flag bits can generally stay in a register
during the execution of the allocation function which means that they
can be branched on with minimal overhead (e.g. TBZ on aarch64).
Differential Revision: https://reviews.llvm.org/D88523
`atomic_compare_exchange_weak` is unused in Scudo, and its associated
test is actually wrong since the weak variant is allowed to fail
spuriously (thanks Roland).
This lead to flakes such as:
```
[ RUN ] ScudoAtomicTest.AtomicCompareExchangeTest
../../zircon/third_party/scudo/src/tests/atomic_test.cpp:98: Failure: Expected atomic_compare_exchange_weak(reinterpret_cast<T *>(&V), &OldVal, NewVal, memory_order_relaxed) is true.
Expected: true
Which is: 01
Actual : atomic_compare_exchange_weak(reinterpret_cast<T *>(&V), &OldVal, NewVal, memory_order_relaxed)
Which is: 00
../../zircon/third_party/scudo/src/tests/atomic_test.cpp💯 Failure: Expected atomic_compare_exchange_weak( reinterpret_cast<T *>(&V), &OldVal, NewVal, memory_order_relaxed) is false.
Expected: false
Which is: 00
Actual : atomic_compare_exchange_weak( reinterpret_cast<T *>(&V), &OldVal, NewVal, memory_order_relaxed)
Which is: 01
../../zircon/third_party/scudo/src/tests/atomic_test.cpp:101: Failure: Expected OldVal == NewVal.
Expected: NewVal
Which is: 24
Actual : OldVal
Which is: 42
[ FAILED ] ScudoAtomicTest.AtomicCompareExchangeTest (0 ms)
[----------] 2 tests from ScudoAtomicTest (1 ms total)
```
So I am removing this, if someone ever needs the weak variant, feel
free to add it back with a test that is not as terrible. This test was
initially ported from sanitizer_common, but their weak version calls
the strong version, so it works for them.
Differential Revision: https://reviews.llvm.org/D88443
The macros INLINE and COMPILER_CHECK always expand to the same thing (inline
and static_assert respectively). Both expansions are standards compliant C++
and are used consistently in the rest of LLVM, so let's improve consistency
with the rest of LLVM by replacing them with the expansions.
Differential Revision: https://reviews.llvm.org/D70793
Summary:
We ran into a problem on Fuchsia where yielding threads would never
be deboosted, ultimately resulting in several threads spinning on the
same TSD, and no possibility for another thread to be scheduled,
dead-locking the process.
While this was fixed in Zircon, this lead to discussions about if
spinning without a break condition was a good decision, and settled on
a new hybrid model that would spin for a while then block.
Currently we are using a number of iterations for spinning that is
mostly arbitrary (based on sanitizer_common values), but this can
be tuned in the future.
Since we are touching `common.h`, we also use this change as a vehicle
for an Android optimization (the page size is fixed in Bionic, so use
a fixed value too).
Reviewers: morehouse, hctim, eugenis, dvyukov, vitalybuka
Reviewed By: hctim
Subscribers: srhines, delcypher, jfb, #sanitizers, llvm-commits
Tags: #llvm, #sanitizers
Differential Revision: https://reviews.llvm.org/D64358
llvm-svn: 365790
Summary:
This CL adds the platform specific code for Fuchsia, Linux & Android,
as well as some tests related to those (more tests to come later).
While some of it is pretty much a straight port of the existing scudo &
sanitizer_common code, the memory mapping functions have been reworked
a bit to fit the limited usage scenario that Scudo has for them.
For Fuchsia, I can now track the Vmar/Vmo pair for memory mappings if
there is an intent to grow or decommit some mapping (that will be
useful for the Primary).
Reviewers: eugenis, vitalybuka, mcgrathr, phosek, flowerhack, morehouse, dmmoore415
Reviewed By: vitalybuka, morehouse
Subscribers: kcc, dvyukov, srhines, mgorny, delcypher, jfb, jdoerfert, #sanitizers, llvm-commits
Tags: #llvm, #sanitizers
Differential Revision: https://reviews.llvm.org/D58184
llvm-svn: 354895
Summary:
This is the initial check-in for the Standalone version of Scudo.
The project is initially going to live in scudo/standalone then will
replace scudo. See http://lists.llvm.org/pipermail/llvm-dev/2019-January/129113.html
for details.
This initial CL is meant to lay out the project structure, of both
code & tests, providing a minimal amount of functionalities, namely
various definitions, some atomic helpers and an intrusive list.
(empty.cc is just here to have a compilation unit, but will go away
in the upcoming CLs).
Initial support is restricted to Linux i386 & x86_64 in make files
and will be extended once things land & work.
We will grow organically from here, adding functionalities in limited
amounts.
Reviewers: morehouse, eugenis, vitalybuka, kcc, mcgrathr, flowerhack
Reviewed By: morehouse, vitalybuka
Subscribers: srhines, mgorny, krytarowski, delcypher, jfb, #sanitizers, llvm-commits
Tags: #llvm, #sanitizers
Differential Revision: https://reviews.llvm.org/D57412
llvm-svn: 353055
Peter Collingbourne