From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9
Date: Mon, 19 Oct 2020 15:10:45 -0500 [thread overview]
Message-ID: <20201019201045.GS2672@gate.crashing.org> (raw)
In-Reply-To: <5ffcb064f695d5285bf1faab91bffa3f9245fc26.1603109522.git.christophe.leroy@csgroup.eu>
On Mon, Oct 19, 2020 at 12:12:46PM +0000, Christophe Leroy wrote:
> GCC 4.9 sometimes fails to build with "m<>" constraint in
> inline assembly.
> --- a/arch/powerpc/include/asm/uaccess.h
> +++ b/arch/powerpc/include/asm/uaccess.h
> @@ -223,7 +223,7 @@ do { \
> "1: " op "%U1%X1 %0,%1 # put_user\n" \
> EX_TABLE(1b, %l2) \
> : \
> - : "r" (x), "m<>" (*addr) \
> + : "r" (x), "m"UPD_CONSTR (*addr) \
> : \
> : label)
>
> @@ -294,7 +294,7 @@ extern long __get_user_bad(void);
> ".previous\n" \
> EX_TABLE(1b, 3b) \
> : "=r" (err), "=r" (x) \
> - : "m<>" (*addr), "i" (-EFAULT), "0" (err))
> + : "m"UPD_CONSTR (*addr), "i" (-EFAULT), "0" (err))
Wow, ugly! But these are the only two places that use this, so
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
I just hope that we get rid of 4.9 before we would use this a lot more ;-)
Segher
prev parent reply other threads:[~2020-10-19 20:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 12:12 [PATCH 1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9 Christophe Leroy
2020-10-19 12:12 ` [PATCH 2/3] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at Christophe Leroy
2020-10-19 20:14 ` Segher Boessenkool
2020-10-19 12:12 ` [PATCH 3/3] powerpc: Fix pre-update addressing in inline assembly Christophe Leroy
2020-10-19 15:35 ` kernel test robot
2020-10-19 18:23 ` Christophe Leroy
2020-10-19 20:24 ` Segher Boessenkool
2020-10-20 7:44 ` Christophe Leroy
2020-10-20 11:51 ` Segher Boessenkool
2020-10-19 20:10 ` Segher Boessenkool [this message]
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