linux-kernel - Re: [PATCH v19 00/27] riscv control-flow integrity for usermode

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Message-ID: <lhu3484i9en.fsf@oldenburg.str.redhat.com>
Date: Tue, 30 Sep 2025 11:20:32 +0200
From: Florian Weimer <fweimer@...hat.com>
To: Deepak Gupta <debug@...osinc.com>
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Subject: Re: [PATCH v19 00/27] riscv control-flow integrity for usermode

* Deepak Gupta:

> In case of shadow stack, it similar situation. If enabled compiler
> decides to insert sspush and sspopchk. They necessarily won't be
> prologue or epilogue but somewhere in function body as deemed fit by
> compiler, thus increasing the complexity of runtime patching.
>
> More so, here are wishing for kernel to do this patching for usermode
> vDSO when there is no guarantee of such of rest of usermode (which if
> was compiled with shadow stack would have faulted before vDSO's
> sspush/sspopchk if ran on pre-zimop hardware)

I think this capability is desirable so that you can use a distribution
kernel during CFI userspace bringup.

Thanks,
Florian