This is done by creating a named shared memory region, unlinking it
and setting up a private (i.e. copy-on-write) mapping of that instead
of a regular anonymous mapping. I've experimented with regular
(sparse) files, but they can not be scaled to the size of MSan shadow
mapping, at least on Linux/X86_64 and ext3 fs.
Controlled by a common flag, decorate_proc_maps, disabled by default.
This patch has a few shortcomings:
* not all mappings are annotated, especially in TSan.
* our handling of memset() of shadow via mmap() puts small anonymous
mappings inside larger named mappings, which looks ugly and can, in
theory, hit the mapping number limit.
llvm-svn: 238621
SetCanPoisonMemory()/CanPoisonMemory() functions are now used
instead of "poison_heap" flag to determine if ASan is allowed
to poison the shadow memory. This allows to hot-patch this
value in runtime (e.g. during ASan activation) without introducing
a data race.
llvm-svn: 224395
This is covered by existing ASan test.
This does not change anything for TSan by default (but provides a flag to
change the threshold size).
Based on a patch by florent.bruneau here:
https://code.google.com/p/address-sanitizer/issues/detail?id=256
llvm-svn: 201400
Evgeniy Stepanov