HWSan on AARCH64 depends on the page size

[apinski-cavium]

From https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102144:
The RingBufferSize inside hwasan/hwasan_thread_list.h depends on the page size being 4k. This does not work with 64k pages and most likely won't work with 16k pages too.
This patch works for me with 64k page size but it really really be using the pagesize rather than a hard coded #:

diff --git a/libsanitizer/hwasan/hwasan_thread_list.h b/libsanitizer/hwasan/hwasan_thread_list.h
index 15916a802d6..c13c5910b95 100644
--- a/libsanitizer/hwasan/hwasan_thread_list.h
+++ b/libsanitizer/hwasan/hwasan_thread_list.h
@@ -57,7 +57,7 @@ static uptr RingBufferSize() {
   // FIXME: increase the limit to 8 once this bug is fixed:
   // https://bugs.llvm.org/show_bug.cgi?id=39030
   for (int shift = 1; shift < 7; ++shift) {
-    uptr size = 4096 * (1ULL << shift);
+    uptr size = (64*4096) * (1ULL << shift);
     if (size >= desired_bytes)
       return size;
   }

[eugenis]

Using pagesize here would be wasteful - ex. on Android we default to a single 4Kb page for the stack ring buffer. I'd rather replace the mmap in SavedStackAllocations with InternalAlloc , this should solve the problem. There is also an efficiency issue in HwasanThreadList::DontNeedThread - if the buffer is smaller than a page, it will never be able to release anything. That's a bit harder to fix, and I'm not sure how significant it actually is.

…

On Sat, Sep 18, 2021 at 5:51 PM Andrew Pinski ***@***.***> wrote: From https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102144: The RingBufferSize inside hwasan/hwasan_thread_list.h depends on the page size being 4k. This does not work with 64k pages and most likely won't work with 16k pages too. This patch works for me with 64k page size but it really really be using the pagesize rather than a hard coded #: diff --git a/libsanitizer/hwasan/hwasan_thread_list.h b/libsanitizer/hwasan/hwasan_thread_list.h index 15916a802d6..c13c5910b95 100644 --- a/libsanitizer/hwasan/hwasan_thread_list.h +++ b/libsanitizer/hwasan/hwasan_thread_list.h @@ -57,7 +57,7 @@ static uptr RingBufferSize() { // FIXME: increase the limit to 8 once this bug is fixed: // https://bugs.llvm.org/show_bug.cgi?id=39030 for (int shift = 1; shift < 7; ++shift) { - uptr size = 4096 * (1ULL << shift); - uptr size = (64*4096) * (1ULL << shift); if (size >= desired_bytes) return size; } — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1446>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADG4SWO3IYLJ4Z5PDKNBQDUCUX2TANCNFSM5EJX6BCA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[pinskia]

So this was fixed now via
llvm/llvm-project@1293e93