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

From: Deepak Gupta <debug@rivosinc.com>
To: Mark Brown <broonie@kernel.org>
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Subject: Re: [PATCH v19 00/27] riscv control-flow integrity for usermode
Date: Fri, 8 Aug 2025 10:20:17 -0700	[thread overview]
Message-ID: <aJYx0Yi3rQcdY6se@debug.ba.rivosinc.com> (raw)
In-Reply-To: <09081487-89ac-4f8d-b9fc-e563f09726d2@sirena.org.uk>

On Fri, Aug 08, 2025 at 12:48:31PM +0100, Mark Brown wrote:
>On Fri, Aug 08, 2025 at 01:23:15AM -0700, Deepak Gupta wrote:
>> On Thu, Aug 07, 2025 at 01:28:36PM +0100, Mark Brown wrote:
>
>> > Do you have an update for my clone3() shadow
>
>> No I don't.
>
>> > stack series that I could roll in for when I repost that after the merge
>> > window, and/or instructions for how to run this stuff for RISC-V on some
>> > emulated platform?
>
>> I would want to write-up instructions. But I don't want you to go through
>> a lot of hassle of building toolchain and bunch of other stuff.
>> Let me see how I can make it easy for you. Will report back.
>
>Thanks.  FWIW I should already be sorted for the kernel build, unless
>there's a super new or specialist toolchain required for this feature

Unlike x86 shadow stack and arm's GCS, push on RISC-V shadow stack is done
using dedicated `sspush` instruction and pop is done using instruction
`sspopchk`. RISC-V vDSO has certain `C` files and they would need shadow stack
push and pop (along with landing pad on them). So that's why kernel compile
would require the toolchain. I'll point you to it.

>(I'd guess I should be fine for the shadow stacks bit?) - it's userspace
>and emulation for the extension I'm missing.

Qemu changes are upstream. I'll provide the command line option.
On userspace, I'll point you to something pre-compiled rootfs.