Re: [kbuild-all] [peterz-queue:locking/rfc 3/5] arch/sh/include/asm/atomic-llsc.h:76:38: note: in ex

[Fengguang Wu <fengguang.wu@intel.com>]

On Fri, Aug 26, 2016 at 02:55:39PM +0200, Peter Zijlstra wrote:
>On Fri, Aug 26, 2016 at 08:31:53PM +0800, Fengguang Wu wrote:
>> On Fri, Aug 26, 2016 at 07:42:25PM +0800, Fengguang Wu wrote:
>
>> It's this atomic_long_fetch_and() that triggered the error.
>> It builds fine if line 505 is commented out.
>>
>> 503         owner = atomic_long_read(&lock->owner);
>> 504         if (!(owner & MUTEX_FLAG_HANDOFF))
>> 505                 owner = atomic_long_fetch_and(MUTEX_FLAGS,
>> &lock->owner);
>> ~~~~~~~~~~~~~~~~~~~~~
>>
>> Cheers,
>> Fengguang
>>
>> >./arch/sh/include/asm/atomic-llsc.h:56:2: error: can’t find a register in class ‘R0_REGS’ while reloading ‘asm’
>> > __asm__ __volatile__ (      \
>> > ^
>> >./arch/sh/include/asm/atomic-llsc.h:76:38: note: in expansion of macro ‘ATOMIC_FETCH_OP’
>> >#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
>> >                                     ^~~~~~~~~~~~~~~
>> >./arch/sh/include/asm/atomic-llsc.h:78:1: note: in expansion of macro ‘ATOMIC_OPS’
>> >ATOMIC_OPS(and)
>> >^~~~~~~~~~
>> >./arch/sh/include/asm/atomic-llsc.h:56:2: error: ‘asm’ operand has impossible constraints
>> > __asm__ __volatile__ (      \
>
>Yes, that much was clear from the above. I just odn't know enough about
>SH asm to know how to go fix it.
>
>There's a note there that says movli.l/movco.l requires r0, and maybe it
>somehow tries to use 2 of those.
>
>But I cannot find the inline asm constraints documented for SH:
>
>  https://gcc.gnu.org/onlinedocs/gcc-6.2.0/gcc/Machine-Constraints.html#Machine-Constraints
>
>Ahh..
>
>  https://github.com/gcc-mirror/gcc/blob/master/gcc/config/sh/constraints.md
>
>has them... would something like so fix things?

It works! Now I got arch/sh/boot/zImage. :)

Tested-by: Fengguang Wu <fengguang.wu@intel.com>

>diff --git a/arch/sh/include/asm/atomic-llsc.h b/arch/sh/include/asm/atomic-llsc.h
>index caea2c45f6c2..1d159ce50f5a 100644
>--- a/arch/sh/include/asm/atomic-llsc.h
>+++ b/arch/sh/include/asm/atomic-llsc.h
>@@ -60,7 +60,7 @@ static inline int atomic_fetch_##op(int i, atomic_t *v)			\
> "	movco.l	%0, @%3					\n"		\
> "	bf	1b					\n"		\
> "	synco						\n"		\
>-	: "=&z" (temp), "=&z" (res)					\
>+	: "=&z" (temp), "=&r" (res)					\
> 	: "r" (i), "r" (&v->counter)					\
> 	: "t");								\
> 									\