From: Alexey Dobriyan <adobriyan@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Mark Hemment <markhemm@googlemail.com>,
Andrew Morton <akpm@linux-foundation.org>,
the arch/x86 maintainers <x86@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
patrice.chotard@foss.st.com,
Mikulas Patocka <mpatocka@redhat.com>,
Lukas Czerner <lczerner@redhat.com>,
Christoph Hellwig <hch@lst.de>,
"Darrick J. Wong" <djwong@kernel.org>,
Chuck Lever <chuck.lever@oracle.com>,
Hugh Dickins <hughd@google.com>,
patches@lists.linux.dev, Linux-MM <linux-mm@kvack.org>,
mm-commits@vger.kernel.org, Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH -final] x86/clear_user: Make it faster
Date: Wed, 6 Jul 2022 12:24:12 +0300 [thread overview]
Message-ID: <YsVUvK/zQaIW749P@localhost.localdomain> (raw)
In-Reply-To: <YsRuUl24zkhpE3s/@zn.tnic>
On Tue, Jul 05, 2022 at 07:01:06PM +0200, Borislav Petkov wrote:
> + asm volatile(
> + "1:\n\t"
> + ALTERNATIVE_3("rep stosb",
> + "call clear_user_erms", ALT_NOT(X86_FEATURE_FSRM),
> + "call clear_user_rep_good", ALT_NOT(X86_FEATURE_ERMS),
> + "call clear_user_original", ALT_NOT(X86_FEATURE_REP_GOOD))
> + "2:\n"
> + _ASM_EXTABLE_UA(1b, 2b)
> + : "+&c" (size), "+&D" (addr), ASM_CALL_CONSTRAINT
> + : "a" (0)
> + /* rep_good clobbers %rdx */
> + : "rdx");
"+c" and "+D" should be enough for 1 instruction assembly?
next parent reply other threads:[~2022-07-06 9:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
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[not found] ` <YrQ1PPB77PBWyaHs@zn.tnic>
[not found] ` <YsRuUl24zkhpE3s/@zn.tnic>
2022-07-06 9:24 ` Alexey Dobriyan [this message]
2022-07-11 10:33 ` [PATCH -final] x86/clear_user: Make it faster Borislav Petkov
2022-07-12 12:32 ` Alexey Dobriyan
2022-08-06 12:49 ` Borislav Petkov
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