Subject: Re: [PATCH v2] powerpc/uaccess: Implement unsafe_put_user() using 'asm goto'

From: Segher Boessenkool <[email-masked]>
Date: Wed, 15 Apr 2020 17:37:47 -0500

Hi!

On Wed, Apr 15, 2020 at 09:25:59AM +0000, Christophe Leroy wrote:
> +#define __put_user_goto(x, ptr, label) \
> +	__put_user_nocheck_goto((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)

This line gets too long, can you break it up somehow?

> +#define __put_user_asm_goto(x, addr, label, op)			\
> +	asm volatile goto(					\
> +		"1:	" op "%U1%X1 %0,%1	# put_user\n"	\
> +		EX_TABLE(1b, %l2)				\
> +		:						\
> +		: "r" (x), "m" (*addr)				\
> +		:						\
> +		: label)

Same "%Un" problem as in the other patch.  You could use "m<>" here,
but maybe just dropping "%Un" is better.

> +#ifdef __powerpc64__
> +#define __put_user_asm2_goto(x, ptr, label)			\
> +	__put_user_asm_goto(x, ptr, label, "std")
> +#else /* __powerpc64__ */
> +#define __put_user_asm2_goto(x, addr, label)			\
> +	asm volatile goto(					\
> +		"1:	stw%U1%X1 %0, %1\n"			\
> +		"2:	stw%U1%X1 %L0, %L1\n"			\
> +		EX_TABLE(1b, %l2)				\
> +		EX_TABLE(2b, %l2)				\
> +		:						\
> +		: "r" (x), "m" (*addr)				\
> +		:						\
> +		: label)
> +#endif /* __powerpc64__ */

Here, you should drop it for sure.

Rest looks fine.

Reviewed-by: Segher Boessenkool <[email-masked]>

Segher