From: Borislav Petkov <bp@alien8.de>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: linux-kernel@vger.kernel.org,
H Peter Anvin <h.peter.anvin@intel.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v3 2/2] x86: Add support for the clwb instruction
Date: Wed, 28 Jan 2015 11:58:52 +0100 [thread overview]
Message-ID: <20150128105852.GF12929@pd.tnic> (raw)
In-Reply-To: <1422377631-8986-3-git-send-email-ross.zwisler@linux.intel.com>
On Tue, Jan 27, 2015 at 09:53:51AM -0700, Ross Zwisler wrote:
> Add support for the new clwb (cache line write back) instruction. This
> instruction was announced in the document "Intel Architecture
> Instruction Set Extensions Programming Reference" with reference number
> 319433-022.
...
> After this function completes the data pointed to by vaddr is has been
> accepted to memory and will be durable if the vaddr points to
> persistent memory.
>
> Regarding the details of how the alternatives assembly is set up, we
> need one additional byte at the beginning of the clflush so that we can
> flip it into a clflushopt by changing that byte into a 0x66 prefix. Two
> options are to either insert a 1 byte ASM_NOP1, or to add a 1 byte
> NOP_DS_PREFIX. Both have no functional effect with the plain clflush,
> but I've been told that executing a clflush + prefix should be faster
> than executing a clflush + NOP.
>
> We had to hard code the assembly for clwb because, lacking the ability
> to assemble the clwb instruction itself, the next closest thing is to
> have an xsaveopt instruction with a 0x66 prefix. Unfortunately xsaveopt
> itself is also relatively new, and isn't included by all the GCC
> versions that the kernel needs to support.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Cc: H Peter Anvin <h.peter.anvin@intel.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Borislav Petkov <bp@alien8.de>
Acked-by: Borislav Petkov <bp@suse.de>
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-01-28 20:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-27 16:53 [PATCH v3 0/2] add support for new persistent memory instructions Ross Zwisler
2015-01-27 16:53 ` [PATCH v3 1/2] x86: Add support for the pcommit instruction Ross Zwisler
2015-01-28 10:58 ` Borislav Petkov
2015-01-28 17:10 ` Elliott, Robert (Server Storage)
2015-01-28 17:21 ` Borislav Petkov
2015-01-28 17:27 ` Ross Zwisler
2015-02-11 22:24 ` H. Peter Anvin
2015-02-19 0:29 ` [tip:x86/asm] " tip-bot for Ross Zwisler
2015-02-19 1:15 ` Ingo Molnar
2015-02-19 17:21 ` Ross Zwisler
2015-02-19 17:33 ` Borislav Petkov
2015-02-19 17:41 ` Ross Zwisler
2015-01-27 16:53 ` [PATCH v3 2/2] x86: Add support for the clwb instruction Ross Zwisler
2015-01-28 10:58 ` Borislav Petkov [this message]
2015-02-11 22:25 ` H. Peter Anvin
2015-02-19 0:29 ` [tip:x86/asm] " tip-bot for Ross Zwisler
2015-04-02 20:31 ` Ross Zwisler
2015-04-03 5:04 ` Ingo Molnar
2015-04-03 5:10 ` [tip:x86/asm] x86/asm: Add support for the CLWB instruction tip-bot for Ross Zwisler
2015-02-05 16:24 ` [PATCH v3 0/2] add support for new persistent memory instructions Ross Zwisler
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=20150128105852.GF12929@pd.tnic \
--to=bp@alien8.de \
--cc=h.peter.anvin@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=ross.zwisler@linux.intel.com \
--cc=tglx@linutronix.de \
/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).