Re: Question about missing "cld" in x86 string assembly code

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From: "nai.xia" <nai.xia@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Brian Gerst <brgerst@gmail.com>, Andi Kleen <ak@linux.intel.com>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: Question about missing "cld" in x86 string assembly code
Date: Thu, 22 Dec 2011 23:52:35 +0800	[thread overview]
Message-ID: <4EF35243.9030600@gmail.com> (raw)
In-Reply-To: <CA+55aFzyEgDUSaNVQ1Nw5SBNd36Cvb-KrVdc1MYj+oRJt8xWgg@mail.gmail.com>



On 2011a1'12ae??18ae?JPY 02:39, Linus Torvalds wrote:
> On Sat, Dec 17, 2011 at 9:08 AM, Brian Gerst<brgerst@gmail.com>  wrote:
>>
>> The i386 ELF ABI states "The direction flag must be set to the
>> a??a??forwarda??a?? (that is, zero) direction before entry and upon exit from
>> a function."  Therefore it can be assumed to be clear, unless
>> explicitly set.
>
> The exception, of course, being bootup, fault and interrupt handlers,
> and after we've called out to foreign code (ie BIOS).

Yeah, I think I see these cld's now. Thanks for the answers!


Nai
>
> So there *are* a few cld's sprinkled around, they are just fairly rare.
>
>                      Linus

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WARNING: multiple messages have this Message-ID (diff)

From: "nai.xia" <nai.xia@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Brian Gerst <brgerst@gmail.com>, Andi Kleen <ak@linux.intel.com>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: Question about missing "cld" in x86 string assembly code
Date: Thu, 22 Dec 2011 23:52:35 +0800	[thread overview]
Message-ID: <4EF35243.9030600@gmail.com> (raw)
In-Reply-To: <CA+55aFzyEgDUSaNVQ1Nw5SBNd36Cvb-KrVdc1MYj+oRJt8xWgg@mail.gmail.com>



On 2011年12月18日 02:39, Linus Torvalds wrote:
> On Sat, Dec 17, 2011 at 9:08 AM, Brian Gerst<brgerst@gmail.com>  wrote:
>>
>> The i386 ELF ABI states "The direction flag must be set to the
>> ‘‘forward’’ (that is, zero) direction before entry and upon exit from
>> a function."  Therefore it can be assumed to be clear, unless
>> explicitly set.
>
> The exception, of course, being bootup, fault and interrupt handlers,
> and after we've called out to foreign code (ie BIOS).

Yeah, I think I see these cld's now. Thanks for the answers!


Nai
>
> So there *are* a few cld's sprinkled around, they are just fairly rare.
>
>                      Linus

next prev parent reply	other threads:[~2011-12-22 15:52 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-17 14:58 Question about missing "cld" in x86 string assembly code Nai Xia
2011-12-17 14:58 ` Nai Xia
2011-12-17 17:08 ` Brian Gerst
2011-12-17 17:08   ` Brian Gerst
2011-12-17 18:39   ` Linus Torvalds
2011-12-17 18:39     ` Linus Torvalds
2011-12-22 15:52     ` nai.xia [this message]
2011-12-22 15:52       ` nai.xia
2011-12-22 15:34   ` nai.xia
2011-12-22 15:34     ` nai.xia
  -- strict thread matches above, loose matches on Subject: below --
2011-12-17 14:52 Nai Xia
2011-12-17 14:52 ` Nai Xia

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