[Lldb-commits] [PATCH] D101361: [LLDB] Support AArch64/Linux watchpoint on tagged addresses

Muhammad Omair Javaid via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Tue May 4 05:14:55 PDT 2021

omjavaid added inline comments.

Comment at: lldb/source/Plugins/Process/Utility/NativeRegisterContextDBReg_arm64.cpp:476
+  return hit_addr & ((1ULL << 56) - 1);
DavidSpickett wrote:
> I think it was fine where it was, my point was just to check whether FreeBSD enables TBI at all.
> Seems like it should be an OS level query. 99% of the time we'd be fine assuming it's enabled but I don't like the idea of pretending that it is and giving a false impression.
> Unless assuming TBI is safe just because the hardware registers don't hold those bits anyway. In which case the comment should justify that.
My first choice was to ignore FreeBSD implementation unless someone from FreeBSD does it after testing. The test-case in this patch is also enabled only for Linux/AArch 64. 
But as an after thought, to make things uniform across LLDB, I made this change given that we are ignoring top-byte of watchpoint install address from all platforms with ABISysV on host side. Also watchpoint address in DBGWVR is 48 bits in normal VA mode and 52 bits in LVA mode so thought ignoring top byte across all platforms seemed safe.
But lets wait for what @mgorny has to say on this.



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