From: Stefan Agner <stefan@agner.ch>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>,
Andrew Lunn <andrew@lunn.ch>, Mans Rullgard <mans@mansr.com>,
Tony Lindgren <tony@atomide.com>, Rob Herring <robh@kernel.org>,
Florian Fainelli <f.fainelli@gmail.com>,
Gregory CLEMENT <gregory.clement@bootlin.com>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
Krzysztof Kozlowski <krzk@kernel.org>,
Kukjin Kim <kgene@kernel.org>,
bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
Jason Cooper <jason@lakedaemon.net>,
Marc Gonzalez <marc.w.gonzalez@free.fr>,
Ray Jui <rjui@broadcom.com>,
Santosh Shilimkar <ssantosh@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Scott Branden <sbranden@broadcom.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 1/3] ARM: use arch_extension directive instead of arch argument
Date: Sun, 24 Mar 2019 22:50:33 +0100 [thread overview]
Message-ID: <b5f1ea23f1e436f2603e0d5993389e8e@agner.ch> (raw)
In-Reply-To: <CAK8P3a0XBN+noCkdGT_TYfPNY1j9CcVH8mTjh_mQL3w+Z6jfaw@mail.gmail.com>
On 23.03.2019 21:06, Arnd Bergmann wrote:
> On Sat, Mar 23, 2019 at 4:52 PM Stefan Agner <stefan@agner.ch> wrote:
>>
>> The LLVM Target parser currently does not allow to specify the security
>> extension as part of -march (see also LLVM Bug 40186 [0]). When trying
>> to use Clang with LLVM's integrated assembler, this leads to a build
>> errors such as this:
>> clang-8: error: the clang compiler does not support '-Wa,-march=armv7-a+sec'
>>
>> Use ".arch_extension sec" to enable the security extension in a more
>> portable fasion.
>>
>> Note that this is technically not exactly the same as the old code
>> checked for availabilty of the security extension by calling as-instr.
>> However, there are already other sites which use ".arch_extension sec"
>> unconditionally, hence de-facto we need an assembler capable of
>> ".arch_extension sec" already today (arch/arm/mm/proc-v7.S). The
>> arch extension "sec" is available since binutils 2.21 according to
>> its documentation [1].
>>
>> [0] https://bugs.llvm.org/show_bug.cgi?id=40186
>> [1] https://sourceware.org/binutils/docs-2.21/as/ARM-Options.html
>>
>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>
> This sounds like a good idea. I think we have platform specific
> minimum toolchain versions elsewhere, but I don't see a problem
> with raising the minimum version for all the armv7ve platforms.
>
> I've added this patch to my randconfig test queue, but please
> send it to arm@kernel.org for inclusion when you have
> collected more Acks.
Cool, will do!
>
> Do you have a git tree with other patches required for the
> integrated assembler? I might try that out as well with
> my randconfig tree. At the moment I'm building with
> clang-8 and a small number of patches on top.
I do have some more work in progress patches. I made some rough commits
and pushed the tree here:
https://github.com/ClangBuiltLinux/linux/commits/arm-fixes-hacks-to-make-llvm-integrated-as-work
This tree compiles for me and a test boot with qemu seems to work.
It seems that LLVM's integrated assembler is capable of assembling
almost the whole kernel a lot can be worked around/fixed on kernel side.
There are only about a handful of files where I still use the GNU
assembler. Haven't looked closely at these cases yet.
There is one issue which probably need a change in LLVM:
https://github.com/ClangBuiltLinux/linux/issues/306
I proposed this fix:
https://reviews.llvm.org/D59733
>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
Thx.
--
Stefan
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next prev parent reply other threads:[~2019-03-24 21:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-23 15:52 [PATCH 1/3] ARM: use arch_extension directive instead of arch argument Stefan Agner
2019-03-23 15:52 ` [PATCH 2/3] ARM: mvebu: drop unnecessary label Stefan Agner
2019-03-23 17:55 ` nicolas.pitre
2019-03-23 15:52 ` [PATCH 3/3] ARM: mvebu: prefix coprocessor operand with p Stefan Agner
2019-03-23 17:56 ` nicolas.pitre
2019-03-23 16:02 ` [PATCH 1/3] ARM: use arch_extension directive instead of arch argument Måns Rullgård
2019-03-23 20:06 ` Arnd Bergmann
2019-03-24 21:50 ` Stefan Agner [this message]
2019-03-31 17:34 ` Arnd Bergmann
2019-04-08 20:23 ` Stefan Agner
2019-03-25 8:11 ` Marc Gonzalez
2019-03-25 10:53 ` Krzysztof Kozlowski
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