linux-kernel - Re: [PATCH] bcm: address clang inline asm incompatibility

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Message-ID: <CAKv+Gu_NCgMmX_LQqi7vtjtP4ofrW+kx8FPgRd4-LWwK=73-xg@mail.gmail.com>
Date:	Wed, 28 Jan 2015 11:15:53 +0000
From:	Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:	Behan Webster <behanw@...verseincode.com>
Cc:	bcm@...thebug.org, f.fainelli@...il.com,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	mporter@...aro.org, bcm-kernel-feedback-list@...adcom.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Alex Elder <elder@...aro.org>
Subject: Re: [PATCH] bcm: address clang inline asm incompatibility

On 28 January 2015 at 05:18, Behan Webster <behanw@...verseincode.com> wrote:
> From: Alex Elder <elder@...aro.org>
>
> My GCC-based build environment likes to call register r12 by the
> name "ip" in inline asm.  Behan Webster informed me that his Clang-
> based build environment likes "r12" instead.
>
> Try to make them both happy.
>
> Signed-off-by: Alex Elder <elder@...aro.org>
> Signed-off-by: Behan Webster <behanw@...verseincode.com>
> ---
>  arch/arm/mach-bcm/bcm_kona_smc.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-bcm/bcm_kona_smc.c b/arch/arm/mach-bcm/bcm_kona_smc.c
> index a55a7ec..3937bd5 100644
> --- a/arch/arm/mach-bcm/bcm_kona_smc.c
> +++ b/arch/arm/mach-bcm/bcm_kona_smc.c
> @@ -106,9 +106,14 @@ int __init bcm_kona_smc_init(void)
>   * request result appropriately.  This result value is found in r0
>   * when the "smc" request completes.
>   */
> +#ifdef __clang__
> +#define R12    "r12"
> +#else  /* !__clang__ */
> +#define R12    "ip"    /* gcc calls r12 "ip" */
> +#endif /* !__clang__ */

Why not just use r12 for both?

>  static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
>  {
> -       register u32 ip asm("ip");      /* Also called r12 */
> +       register u32 ip asm(R12);       /* Also called r12 */
>         register u32 r0 asm("r0");
>         register u32 r4 asm("r4");
>         register u32 r5 asm("r5");
> @@ -120,7 +125,7 @@ static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
>
>         asm volatile (
>                 /* Make sure we got the registers we want */
> -               __asmeq("%0", "ip")
> +               __asmeq("%0", R12)
>                 __asmeq("%1", "r0")
>                 __asmeq("%2", "r4")
>                 __asmeq("%3", "r5")
> --
> 1.9.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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