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

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Date:	Wed, 28 Jan 2015 08:11:16 -0600
From:	Alex Elder <elder@...aro.org>
To:	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	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>
Subject: Re: [PATCH] bcm: address clang inline asm incompatibility

On 01/28/2015 05:15 AM, Ard Biesheuvel wrote:
> 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?

Yes, that would have been an obvious fix.  But the
assembler (in the GCC environment) doesn't accept that.

					-Alex

> 
>>  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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