DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:sender:in-reply-to:references:date
         :x-google-sender-auth:message-id:subject:from:to:cc:content-type
         :content-transfer-encoding;
        b=AA+KEm7upPmnDOMO+B2MpJbBqJxQ7dzz5tIc2vZIegBk/rBZYbBEpJCd6sfLcUTC5q
         AeTk0dxMaRUqhfGwXjlmk6xxhzyHmGkIELYy1JPoJ5qRsyrIhYpYoq3RYEbF8DDX/iBn
         o4598JnlChJBcUcedfmP/SlhnafjElou7DtrE=
MIME-Version: 1.0
In-Reply-To: <1283011478-27237-8-git-send-email-brgerst@gmail.com>
References: <1283011478-27237-1-git-send-email-brgerst@gmail.com>
	<1283011478-27237-8-git-send-email-brgerst@gmail.com>
Date: Sun, 29 Aug 2010 21:45:11 +0300
Message-ID: <AANLkTi=+cEywooPp-ERx2+7GL3fs_d-xQ_fX9A7pc9St@mail.gmail.com>
Subject: Re: [PATCH 07/11] x86-64: Simplify constraints for fxsave/fxtstor
From: Pekka Enberg <penberg@kernel.org>
To: Brian Gerst <brgerst@gmail.com>
Cc: hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8BIT
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1781
Lines: 43

On Sat, Aug 28, 2010 at 7:04 PM, Brian Gerst <brgerst@gmail.com> wrote:
> Use the "R" constraint (legacy register) instead of listing all the
> possible registers. ?Clean up the comments as well.
>
> Signed-off-by: Brian Gerst <brgerst@gmail.com>
> ---
> ?arch/x86/include/asm/i387.h | ? 44 ++++++++++++++++--------------------------
> ?1 files changed, 17 insertions(+), 27 deletions(-)
>
> diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
> index 8b40a83..768fcb2 100644
> --- a/arch/x86/include/asm/i387.h
> +++ b/arch/x86/include/asm/i387.h
> @@ -81,6 +81,7 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
> ?{
> ? ? ? ?int err;
>
> + ? ? ? /* See comment in fxsave() below. */
> ? ? ? ?asm volatile("1: ?rex64/fxrstor (%[fx])\n\t"
> ? ? ? ? ? ? ? ? ? ? "2:\n"
> ? ? ? ? ? ? ? ? ? ? ".section .fixup,\"ax\"\n"
> @@ -89,11 +90,7 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
> ? ? ? ? ? ? ? ? ? ? ".previous\n"
> ? ? ? ? ? ? ? ? ? ? _ASM_EXTABLE(1b, 3b)
> ? ? ? ? ? ? ? ? ? ? : [err] "=r" (err)
> -#if 0 /* See comment in fxsave() below. */
> - ? ? ? ? ? ? ? ? ? ?: [fx] "r" (fx), "m" (*fx), "0" (0));
> -#else
> - ? ? ? ? ? ? ? ? ? ?: [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
> -#endif
> + ? ? ? ? ? ? ? ? ? ?: [fx] "R" (fx), "m" (*fx), "0" (0));

Please correct me if I'm wrong but "legacy registers" also include bp
and sp that are not part of the original constraints:

http://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html

So why is it OK to use "R" here?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/