From: Andrea Corallo <andrea.corallo@arm.com>
To: Andrea Corallo via Gcc-patches <gcc-patches@gcc.gnu.org>
Cc: nd <nd@arm.com>, Richard Earnshaw <Richard.Earnshaw@arm.com>
Subject: Re: [PATCH] [1/2] arm: Implement cortex-M return signing address codegen
Date: Wed, 24 Nov 2021 11:08:18 +0100 [thread overview]
Message-ID: <gkr5yshg92l.fsf@arm.com> (raw)
In-Reply-To: <gkrlf23f0hp.fsf@arm.com> (Andrea Corallo via Gcc-patches's message of "Fri, 5 Nov 2021 09:52:18 +0100")
Andrea Corallo via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> Hi all,
>
> this patch enables address return signature and verification based on
> Armv8.1-M Pointer Authentication [1].
>
> To sign the return address, we use the PAC R12, LR, SP instruction
> upon function entry. This is signing LR using SP and storing the
> result in R12. R12 will be pushed into the stack.
>
> During function epilogue R12 will be popped and AUT R12, LR, SP will
> be used to verify that the content of LR is still valid before return.
>
> Here an example of PAC instrumented function prologue and epilogue:
>
> pac r12, lr, sp
> push {r3, r7, lr}
> push {r12}
> sub sp, sp, #4
> [...] function body
> add sp, sp, #4
> pop {r12}
> pop {r3, r7, lr}
> aut r12, lr, sp
> bx lr
>
> The patch also takes care of generating a PACBTI instruction in place
> of the sequence BTI+PAC when Branch Target Identification is enabled
> contextually.
>
> These two patches apply on top of Tejas series posted here [2].
>
> Regressioned and arm-linux-gnu aarch64-linux-gnu bootstraped.
>
> Best Regards
>
> Andrea
>
> [1] <https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/armv8-1-m-pointer-authentication-and-branch-target-identification-extension>
> [2] <https://gcc.gnu.org/pipermail/gcc-patches/2021-October/581176.html>
Ping
Best Regards
Andrea
next prev parent reply other threads:[~2021-11-24 10:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-05 8:52 Andrea Corallo
2021-11-24 10:08 ` Andrea Corallo [this message]
2021-12-08 10:33 ` Andrea Corallo
2021-12-08 11:31 ` Richard Earnshaw
2021-12-17 15:52 ` Andrea Corallo
2021-12-17 16:55 ` Richard Earnshaw
2021-12-17 17:22 ` Andrea Corallo
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