While the instrumentation never calls dfsan_union in fast16labels mode,
the custom wrappers do. We detect fast16labels mode by checking whether
any labels have been created. If not, we must be using fast16labels
mode.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D86012
Unmapping and remapping is dangerous since another thread could touch
the shadow memory while it is unmapped. But there is really no need to
unmap anyway, since mmap(MAP_FIXED) will happily clobber the existing
mapping with zeroes. This is thread-safe since the mmap() is done under
the same kernel lock as page faults are done.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D85947
Adds the -fast-16-labels flag, which enables efficient instrumentation
for DFSan when the user needs <=16 labels. The instrumentation
eliminates most branches and most calls to __dfsan_union or
__dfsan_union_load.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D84371
Support fast16labels in `dfsan_has_label`, and print an error for all
other API functions. For `dfsan_dump_labels` we return silently rather
than crashing since it is also called from the atexit handler where it
is undefined behavior to call exit() again.
Reviewed By: kcc
Differential Revision: https://reviews.llvm.org/D84215
Summary:
Support fast16labels in `dfsan_has_label`, and print an error for all
other API functions.
Reviewers: kcc, vitalybuka, pcc
Reviewed By: kcc
Subscribers: jfb, llvm-commits, #sanitizers
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D84215
Matt Morehouse