From: Matthew Malcomson <matthew.malcomson@arm.com>
To: Richard Earnshaw <Richard.Earnshaw@foss.arm.com>,
Florian Mayer <fmayer@google.com>,
gcc@gcc.gnu.org
Cc: Evgenii Stepanov <eugenis@google.com>, Fangrui Song <maskray@google.com>
Subject: Re: .eh_frame augmentation character for MTE stack tagging
Date: Mon, 6 Jun 2022 15:15:09 +0100 [thread overview]
Message-ID: <7f637a14-4045-76b3-c8cd-3de18856ecf5@arm.com> (raw)
In-Reply-To: <00728f04-2b84-13a3-2ebb-34f5953d28a5@foss.arm.com>
Hi there,
Just to mention that this decision has been included in the Arm ABI project.
https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst#id22
MM
On 6/6/22 12:00, Richard Earnshaw via Gcc wrote:
>
>
> On 04/06/2022 00:52, Florian Mayer via Gcc wrote:
>> 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
>
> Hi Florian,
>
> This is something that needs to be specified in the ABI, not just agreed
> between a couple of compilers. So while the community input is helpful,
> it isn't enough.
>
> The correct place to do this is in the ABI project here:
> https://github.com/ARM-software/abi-aa
>
> R.
prev parent reply other threads:[~2022-06-06 14:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-03 23:52 Florian Mayer
2022-06-06 11:00 ` Richard Earnshaw
2022-06-06 14:15 ` Matthew Malcomson [this message]
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