From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 2/2] arm64: signal: Report signal frame size to userspace via auxv
Date: Fri, 25 May 2018 16:20:23 +0100 [thread overview]
Message-ID: <20180525152022.GE3255@arm.com> (raw)
In-Reply-To: <1527261428-6662-3-git-send-email-Dave.Martin@arm.com>
On Fri, May 25, 2018 at 04:17:08PM +0100, Dave Martin wrote:
> Stateful CPU architecture extensions may require the signal frame
> to grow to a size that exceeds the arch's MINSIGSTKSZ #define.
> However, changing this #define is an ABI break.
>
> To allow userspace the option of determining the signal frame size
> in a more forwards-compatible way, this patch adds a new auxv entry
> tagged with AT_MINSIGSTKSZ, which provides the maximum signal frame
> size that the process can observe during its lifetime.
>
> If AT_MINSIGSTKSZ is absent from the aux vector, the caller can
> assume that the MINSIGSTKSZ #define is sufficient. This allows for
> a consistent interface with older kernels that do not provide
> AT_MINSIGSTKSZ.
>
> The idea is that libc could expose this via sysconf() or some
> similar mechanism.
>
> There is deliberately no AT_SIGSTKSZ. The kernel knows nothing
> about userspace's own stack overheads and should not pretend to
> know.
Thanks, Dave.
Acked-by: Will Deacon <will.deacon@arm.com>
Will
next prev parent reply other threads:[~2018-05-25 15:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-25 15:17 [PATCH v5 0/2] arm64: signal: Report signal frame size to userspace via auxv Dave Martin
2018-05-25 15:17 ` [PATCH v5 1/2] arm64/sve: Thin out initialisation sanity-checks for sve_max_vl Dave Martin
2018-05-25 15:17 ` [PATCH v5 2/2] arm64: signal: Report signal frame size to userspace via auxv Dave Martin
2018-05-25 15:20 ` Will Deacon [this message]
2018-05-29 20:42 ` Will Deacon
2018-05-30 10:48 ` Dave Martin
2018-05-31 17:20 ` Will Deacon
2018-06-01 8:44 ` Dave Martin
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