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Re: [PATCH v2 14/28] arm64/sve: Backend logic for setting the vector length
- From: Catalin Marinas <catalin dot marinas at arm dot com>
- To: Dave Martin <Dave dot Martin at arm dot com>
- Cc: linux-arch at vger dot kernel dot org, libc-alpha at sourceware dot org, gdb at sourceware dot org, Ard Biesheuvel <ard dot biesheuvel at linaro dot org>, Szabolcs Nagy <szabolcs dot nagy at arm dot com>, Richard Sandiford <richard dot sandiford at arm dot com>, Yao Qi <Yao dot Qi at arm dot com>, Will Deacon <will dot deacon at arm dot com>, Alan Hayward <alan dot hayward at arm dot com>, Alex Bennée <alex dot bennee at linaro dot org>, kvmarm at lists dot cs dot columbia dot edu, linux-arm-kernel at lists dot infradead dot org
- Date: Wed, 13 Sep 2017 15:11:23 -0700
- Subject: Re: [PATCH v2 14/28] arm64/sve: Backend logic for setting the vector length
- Authentication-results: sourceware.org; auth=none
- References: <1504198860-12951-1-git-send-email-Dave.Martin@arm.com> <1504198860-12951-15-git-send-email-Dave.Martin@arm.com> <20170913172911.3ca2h6cpju7etifi@localhost> <20170913190611.GC23415@e103592.cambridge.arm.com>
On Wed, Sep 13, 2017 at 08:06:12PM +0100, Dave P Martin wrote:
> On Wed, Sep 13, 2017 at 10:29:11AM -0700, Catalin Marinas wrote:
> > On Thu, Aug 31, 2017 at 06:00:46PM +0100, Dave P Martin wrote:
> > > This patch implements the core logic for changing a task's vector
> > > length on request from userspace. This will be used by the ptrace
> > > and prctl frontends that are implemented in later patches.
> > >
> > > The SVE architecture permits, but does not require, implementations
> > > to support vector lengths that are not a power of two. To handle
> > > this, logic is added to check a requested vector length against a
> > > possibly sparse bitmap of available vector lengths at runtime, so
> > > that the best supported value can be chosen.
> > >
> > > Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> > > Cc: Alex Bennée <alex.bennee@linaro.org>
> >
> > Can this be merged with patch 20? It seems to add the PR_ definitions
> > which get actually used later when the prctl interface is added.
>
> This patch is used both by patch 19 and by patch 20, which I preferred
> not to merge with each other: ptrace and prctl are significantly
> different things.
>
> The prctl bit definitions are added here because they are the canonical
> definitions used by both interfaces. The ptrace #defines are based on
> them.
>
> Does it make sense if I merge patch 20 into this one and apply patch 19
> on top? This avoide the appearance of prctl #defines with no prctl
> implementation.
That's fine, you can bring patch 20 forward. If there are other
non-trivial issues, feel free to ignore my comment.
--
Catalin