From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
jing.lin@intel.com, bp@alien8.de, x86@kernel.org
Subject: Re: [PATCH] x86/asm: Add support for MOVDIR64B instruction
Date: Thu, 1 Aug 2019 23:28:08 +0300 [thread overview]
Message-ID: <20190801202808.e2cqlqetixie4gcu@box> (raw)
In-Reply-To: <20190801194947.GA12033@agluck-desk2.amr.corp.intel.com>
On Thu, Aug 01, 2019 at 12:49:48PM -0700, Luck, Tony wrote:
> On Thu, Aug 01, 2019 at 10:43:48PM +0300, Alexey Dobriyan wrote:
> > > +static inline void movdir64b(void *dst, const void *src)
> > > +{
> > > + /* movdir64b [rdx], rax */
> > > + asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
> > > + : "=m" (*(char *)dst)
> > ^^^^^^^^^^
> >
> > > + : "d" (src), "a" (dst));
> > > +}
> >
> > Probably needs fake 64-byte type, so that compiler knows what is dirty.
>
> Would that be something like this?
>
> static inline void movdir64b(void *dst, const void *src)
> {
> struct dstbytes {
> char pad[64];
> };
>
> /* movdir64b [rdx], rax */
> asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
> : "=m" (*(struct dstbytes *)dst)
> : "d" (src), "a" (dst));
> }
>
> Or did you have something else in mind?
Or should we add "memory" clobber instead, like we do for string
operations?
static inline void movdir64b(void *dst, const void *src)
{
/* movdir64b [rdx], rax */
asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
: : "d" (src), "a" (dst) : "memory");
}
--
Kirill A. Shutemov
next prev parent reply other threads:[~2019-08-01 20:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 19:43 [PATCH] x86/asm: Add support for MOVDIR64B instruction Alexey Dobriyan
2019-08-01 19:49 ` Luck, Tony
2019-08-01 20:28 ` Kirill A. Shutemov [this message]
2019-08-01 20:36 ` Borislav Petkov
2019-08-01 22:06 ` Luck, Tony
2019-08-02 14:40 ` Borislav Petkov
2019-08-05 17:50 ` Lin, Jing
2019-08-01 21:53 ` Alexey Dobriyan
2019-08-02 8:15 ` Peter Zijlstra
2019-08-02 12:58 ` Kirill A. Shutemov
-- strict thread matches above, loose matches on Subject: below --
2019-07-30 23:05 Kirill A. Shutemov
2019-07-31 0:24 ` jinglin
2019-08-01 10:03 ` Borislav Petkov
2019-08-01 11:03 ` Kirill A. Shutemov
2019-08-01 19:20 ` Luck, Tony
2019-08-01 19:36 ` Borislav Petkov
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