* Re: [PATCH v2] riscv: cif: reduce shadow stack size limit from 4GB to 2GB
[not found] <20260428024105.645162-1-zong.li@sifive.com>
@ 2026-05-14 1:20 ` Paul Walmsley
2026-05-14 3:22 ` Zong Li
0 siblings, 1 reply; 2+ messages in thread
From: Paul Walmsley @ 2026-05-14 1:20 UTC (permalink / raw)
To: Zong Li
Cc: pjw, palmer, aou, alex, debug, linux-riscv, linux-kernel,
david.laight.linux
Hi,
On Mon, 27 Apr 2026, Zong Li wrote:
> Follow the ARM64 GCS (Guarded Control Stack) implementation approach
> by reducing the shadow stack size allocation from min(RLIMIT_STACK, 4GB)
> to min(RLIMIT_STACK/2, 2GB). see commit '506496bcbb42 "arm64/gcs: Ensure
> that new threads have a GCS")'
Sashiko caught that this patch doesn't exactly follow the ARM
implementation, in that it doesn't include the max(PAGE_SIZE, size)
constraint, which covers the case where someone sets RLIMIT_STACK to
something absurdly small ( < PAGE_SIZE ). Care to fix that and post a new
version?
thanks
- Paul
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v2] riscv: cif: reduce shadow stack size limit from 4GB to 2GB
2026-05-14 1:20 ` [PATCH v2] riscv: cif: reduce shadow stack size limit from 4GB to 2GB Paul Walmsley
@ 2026-05-14 3:22 ` Zong Li
0 siblings, 0 replies; 2+ messages in thread
From: Zong Li @ 2026-05-14 3:22 UTC (permalink / raw)
To: Paul Walmsley
Cc: palmer, aou, alex, debug, linux-riscv, linux-kernel,
david.laight.linux
On Thu, May 14, 2026 at 9:20 AM Paul Walmsley <pjw@kernel.org> wrote:
>
> Hi,
>
> On Mon, 27 Apr 2026, Zong Li wrote:
>
> > Follow the ARM64 GCS (Guarded Control Stack) implementation approach
> > by reducing the shadow stack size allocation from min(RLIMIT_STACK, 4GB)
> > to min(RLIMIT_STACK/2, 2GB). see commit '506496bcbb42 "arm64/gcs: Ensure
> > that new threads have a GCS")'
>
> Sashiko caught that this patch doesn't exactly follow the ARM
> implementation, in that it doesn't include the max(PAGE_SIZE, size)
> constraint, which covers the case where someone sets RLIMIT_STACK to
> something absurdly small ( < PAGE_SIZE ). Care to fix that and post a new
> version?
>
Ok. I will send the next version to include that. Thanks for pointing it out.
>
> thanks
>
> - Paul
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-05-14 1:20 ` [PATCH v2] riscv: cif: reduce shadow stack size limit from 4GB to 2GB Paul Walmsley
2026-05-14 3:22 ` Zong Li
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