fmayer added a comment.
In D103562#3702962 <https://reviews.llvm.org/D103562#3702962>, @smd wrote:
> Hi folks,
>
> I've been working on support hwasan for risc-v and I believe I've found an
> issue with the existing lit tests this commit causes.
> Tests stack-{oob,uar,uas}.c check for correct backtrace being printed. From
> the code and comments the idea is to not to print any hwasan related
> frames(see the code and comments below).
>
> void HandleTagMismatch(AccessInfo ai, uptr pc, uptr frame, void *uc,
>
> uptr *registers_frame) {
>
> InternalMmapVector<BufferedStackTrace> stack_buffer(1);
>
> BufferedStackTrace *stack = stack_buffer.data();
>
> stack->Reset();
>
> stack->Unwind(pc, frame, uc, common_flags()->fast_unwind_on_fatal);
>
>
>
> // The second stack frame contains the failure __hwasan_check function,
> as
> // we have a stack frame for the registers saved in __hwasan_tag_mismatch
> that
> // we wish to ignore. This (currently) only occurs on AArch64, as x64
>
> // implementations use SIGTRAP to implement the failure, and thus do not
> go
> // through the stack saver.
>
> if (registers_frame && stack->trace && stack->size > 0) {
>
> stack->trace++;
>
> stack->size--;
>
> }
>
> Before this commit the return address and frame pointer to were taken
> directly from **hwasan_tag_mismatch4**, while after the commit those
> addresses are calculated after another function being called from
> hwasan_tag_mismatch4 (the **HwasanTagMismatch** one).
> So, if I understand it correctly, now it looks like 2 stack frames must be
> ignored(for **hwasan_tag_mismatch4** and **HwasanTagMismatch**) to get a
> proper backtrace.
> What do you think?
>
> Thanks
Yes, but I am not sure we can *rely* on that being the case as is. LTO could
conceivably inline this – in which case it would be one, right?
================
Comment at: compiler-rt/lib/hwasan/hwasan.cpp:205
+ if (registers_frame && stack->trace && stack->size > 0) {
+ stack->trace++;
+ stack->size--;
----------------
vitalybuka wrote:
> maybe we should pop everything up to "pc" to avoid issues with nested calls?
>
> For most users hwasan frames are not very useful. However if you work on
> sanitizer, some frames can be a useful info. So I don't mind we just relax
> test cases to accommodate this nesting.
>
> cc @smd
This is probably for another patch though, right? This is already like this on
the LHS.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D103562/new/
https://reviews.llvm.org/D103562
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