From: Palmer Dabbelt <palmer@sifive.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: aou@eecs.berkeley.edu, nickhu@andestech.com,
alankao@andestech.com, Atish Patra <Atish.Patra@wdc.com>,
Greg KH <gregkh@linuxfoundation.org>,
Anup Patel <Anup.Patel@wdc.com>,
linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
zong@andestech.com, alexios.zavras@intel.com, glider@google.com,
green.hu@gmail.com, Paul Walmsley <paul.walmsley@sifive.com>,
aryabinin@virtuozzo.com, tglx@linutronix.de, deanbo422@gmail.com,
linux-riscv@lists.infradead.org, dvyukov@google.com
Subject: Re: [PATCH 1/2] riscv: Add memmove string operation.
Date: Tue, 13 Aug 2019 16:50:58 -0700 (PDT) [thread overview]
Message-ID: <mhng-ba92c635-7087-4783-baa5-2a111e0e2710@palmer-si-x1e> (raw)
In-Reply-To: <20190812150446.GI26897@infradead.org>
On Mon, 12 Aug 2019 08:04:46 PDT (-0700), Christoph Hellwig wrote:
> On Wed, Aug 07, 2019 at 03:19:14PM +0800, Nick Hu wrote:
>> There are some features which need this string operation for compilation,
>> like KASAN. So the purpose of this porting is for the features like KASAN
>> which cannot be compiled without it.
>>
>> KASAN's string operations would replace the original string operations and
>> call for the architecture defined string operations. Since we don't have
>> this in current kernel, this patch provides the implementation.
>>
>> This porting refers to the 'arch/nds32/lib/memmove.S'.
>
> This looks sensible to me, although my stringop asm is rather rusty,
> so just an ack and not a real review-by:
>
> Acked-by: Christoph Hellwig <hch@lst.de>
FWIW, we just write this in C everywhere else and rely on the compiler to
unroll the loops. I always prefer C to assembly when possible, so I'd prefer
if we just adopt the string code from newlib. We have a RISC-V-specific memcpy
in there, but just use the generic memmove.
Maybe the best bet here would be to adopt the newlib memcpy/memmove as generic
Linux functions? They're both in C so they should be fine, and they both look
faster than what's in lib/string.c. Then everyone would benefit and we don't
need this tricky RISC-V assembly. Also, from the look of it the newlib code is
faster because the inner loop is unrolled.
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2019-08-13 23:51 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 7:19 [PATCH 0/2] KASAN support for RISC-V Nick Hu
2019-08-07 7:19 ` [PATCH 1/2] riscv: Add memmove string operation Nick Hu
2019-08-12 15:04 ` Christoph Hellwig
2019-08-13 23:50 ` Palmer Dabbelt [this message]
2019-08-14 2:22 ` Paul Walmsley
2019-08-14 3:27 ` Nick Hu
2019-08-14 17:03 ` Paul Walmsley
2019-08-15 3:12 ` Nick Hu
2019-08-15 18:27 ` Paul Walmsley
2019-08-19 6:29 ` Nick Hu
2019-08-14 18:33 ` Palmer Dabbelt
2019-08-22 15:59 ` Andrey Ryabinin
2019-08-27 9:07 ` Nick Hu
2019-08-27 9:33 ` Andrey Ryabinin
2019-08-28 3:06 ` Nick Hu
2019-08-07 7:19 ` [PATCH 2/2] riscv: Add KASAN support Nick Hu
2019-08-12 15:10 ` Christoph Hellwig
2019-08-14 7:44 ` Nick Hu
2019-08-22 17:08 ` Andrey Ryabinin
2019-09-03 15:08 ` Daniel Axtens
2019-09-04 2:24 ` Nick Hu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=mhng-ba92c635-7087-4783-baa5-2a111e0e2710@palmer-si-x1e \
--to=palmer@sifive.com \
--cc=Anup.Patel@wdc.com \
--cc=Atish.Patra@wdc.com \
--cc=alankao@andestech.com \
--cc=alexios.zavras@intel.com \
--cc=aou@eecs.berkeley.edu \
--cc=aryabinin@virtuozzo.com \
--cc=deanbo422@gmail.com \
--cc=dvyukov@google.com \
--cc=glider@google.com \
--cc=green.hu@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=hch@infradead.org \
--cc=kasan-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=nickhu@andestech.com \
--cc=paul.walmsley@sifive.com \
--cc=tglx@linutronix.de \
--cc=zong@andestech.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).