We used to update the deallocated block with
atomic_compare_exchange_strong to ensure the concurrent double-free will
be detected. However, this operation incurs huge performance overhead
which takes over 50% execution time in deallocate(). Given that we
already have the checksum to guard the most double-free cases and other
block verifications in the primary allocator, use atomic-store instead.
Here "memory initialization" refers to zero- or pattern-init on
non-MTE hardware, or (where possible to avoid) memory tagging on MTE
hardware. With shared TSD the per-thread memory initialization state
is stored in bit 0 of the TLS slot, similar to PointerIntPair in LLVM.
Differential Revision: https://reviews.llvm.org/D87739
Summary:
This CL makes unit tests compatible with Fuchsia's zxtest. This
required a few changes here and there, but also unearthed some
incompatibilities that had to be addressed.
A header is introduced to allow to account for the zxtest/gtest
differences, some `#if SCUDO_FUCHSIA` are used to disable incompatible
code (the 32-bit primary, or the exclusive TSD).
It also brought to my attention that I was using
`__scudo_default_options` in different tests, which ended up in a
single binary, and I am not sure how that ever worked. So move
this to the main cpp.
Additionally fully disable the secondary freelist on Fuchsia as we do
not track VMOs for secondary allocations, so no release possible.
With some modifications to Scudo's BUILD.gn in Fuchsia:
```
[==========] 79 tests from 23 test cases ran (10280 ms total).
[ PASSED ] 79 tests
```
Reviewers: mcgrathr, phosek, hctim, pcc, eugenis, cferris
Subscribers: srhines, jfb, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D70682
