From: Dave Martin <Dave.Martin@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
linux-arm-kernel@lists.infradead.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v2 1/4] kselftest/arm64: Provide a helper binary and "library" for SVE RDVL
Date: Thu, 29 Jul 2021 17:17:26 +0100 [thread overview]
Message-ID: <20210729161726.GQ1724@arm.com> (raw)
In-Reply-To: <20210729160334.GQ4670@sirena.org.uk>
On Thu, Jul 29, 2021 at 05:03:34PM +0100, Mark Brown wrote:
> On Thu, Jul 29, 2021 at 02:27:04PM +0100, Dave P Martin wrote:
> > On Thu, Jul 29, 2021 at 12:22:17PM +0100, Mark Brown wrote:
>
> > > Yeah, it doesn't seem to be in the slightest bit idiomatic for the arm64
> > > asm code the kernel has. I don't know if you think it's worth adding
> > > that to SYM_FUNC_START now we have it though?
>
> > Actually, I think the core definition of SYM_FUNC_END() in
> > <linux/linkage.h> does this.
>
> Ah, so it does.
>
> > It would be good to pick up the common linkage macros; if we have to
> > sprinkle .type manually all over the tests people will likely make
> > mistakes, to that's probably not worth it.
>
> > If picking up the macros isn't trivial to do, I guess it's not that
> > important at this stage.
>
> They're not exported from the kernel at all at the minute so that'd be a
> whole new block of work that feels out of scope here, we already have a
> stack of asm code in selftests.
Agreed. Feels like it might be a good idea at some point, but it's
orthogonal to this series, and for now nothing breaks.
> > > that those are outside the kernel either. We will have to do something
> > > like that if anyone starts building userspace with BTI though (or I
> > > might just shove a BTI C in there unconditionally, I'm sure we'll cope
> > > with the overhead on older systems).
>
> > I thought about that, but that .S file isn't annotated as supporting
> > BTI, so I guess there's no problem for now(?)
>
> True, we'll generate linker warnings but it should otherwise sort itself
> out unless someone forced BTI mode. The whole annotation thing really
> isn't fun to deal with for assembly code, hopefully there'll be some
> toolchain improvements in this area at some point.
Ack
Cheers
---Dave
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next prev parent reply other threads:[~2021-07-29 16:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-28 16:33 [PATCH v2 0/4] kselftest/arm64: Vector length configuration tests Mark Brown
2021-07-28 16:33 ` [PATCH v2 1/4] kselftest/arm64: Provide a helper binary and "library" for SVE RDVL Mark Brown
2021-07-29 9:52 ` Dave Martin
2021-07-29 11:22 ` Mark Brown
2021-07-29 13:27 ` Dave P Martin
2021-07-29 16:03 ` Mark Brown
2021-07-29 16:17 ` Dave Martin [this message]
2021-07-28 16:33 ` [PATCH v2 2/4] kselftest/arm64: Validate vector lengths are set in sve-probe-vls Mark Brown
2021-07-29 9:52 ` Dave Martin
2021-07-28 16:33 ` [PATCH v2 3/4] kselftest/arm64: Add tests for SVE vector configuration Mark Brown
2021-07-29 9:52 ` Dave Martin
2021-07-28 16:33 ` [PATCH v2 4/4] kselftest/arm64: Add a TODO list for floating point tests Mark Brown
2021-07-29 9:52 ` Dave Martin
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