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From: Florian Mayer <fmayer@google.com>
To: gcc@gcc.gnu.org
Cc: Evgenii Stepanov <eugenis@google.com>, Fangrui Song <maskray@google.com>
Subject: .eh_frame augmentation character for MTE stack tagging
Date: Fri, 3 Jun 2022 16:52:38 -0700	[thread overview]
Message-ID: <CAJAyTCDHRLfxUWARpH5fzis9sqWtuF1PV5MsjLuyYU3LxPx9cA@mail.gmail.com> (raw)

Hey!

We are in the process of implementing MTE (Memory Tagging Extension)
stack tagging in LLVM. To support stack tagging in combination with
exceptions, we need to make sure that the unwinder will untag stack
frames, to avoid leaving behind stale tags. As such, we need some way
to communicate to the unwinder to do that.

In a discussion on llvm-dev [1], it was decided the best way to go
forward with this would be to add a new character ('G' for taG, as the
MTE instructions stg etc.) to the eh_frame augmentation string, and
then handle that in libunwind by clearing the tags of the respective
frame.

How does that sound? Would that be a good course of action for GCC as well?

Thanks,
Florian

[1]: https://lists.llvm.org/pipermail/llvm-dev/2020-May/141345.html

             reply	other threads:[~2022-06-03 23:52 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-03 23:52 Florian Mayer [this message]
2022-06-06 11:00 ` Richard Earnshaw
2022-06-06 14:15   ` Matthew Malcomson

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