Re: [PATCHv3] mips: Do not include hi and lo in clobber list for R6

["Maciej W. Rozycki" <macro@wdc.com>]

On Sat, 1 Aug 2020, Romain Naour wrote:

> v3 Avoid duplicate code (Maciej W. Rozycki)
> v2 use MIPS_ISA_REV instead of __mips_isa_rev (Alexander Lobakin)
> ---
>  arch/mips/include/asm/vdso/gettimeofday.h | 30 +++++++++++++++++++----
>  1 file changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/mips/include/asm/vdso/gettimeofday.h b/arch/mips/include/asm/vdso/gettimeofday.h
> index c63ddcaea54c..93008551282e 100644
> --- a/arch/mips/include/asm/vdso/gettimeofday.h
> +++ b/arch/mips/include/asm/vdso/gettimeofday.h
> @@ -35,7 +35,11 @@ static __always_inline long gettimeofday_fallback(
>  	: "=r" (ret), "=r" (error)
>  	: "r" (tv), "r" (tz), "r" (nr)
>  	: "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13",
> -	  "$14", "$15", "$24", "$25", "hi", "lo", "memory");
> +	  "$14", "$15", "$24", "$25",
> +#if MIPS_ISA_REV < 6
> +	  "hi", "lo",
> +#endif
> +          "memory");

 Can you please use a helper macro, say GCC_REGS_HI_LO, moving the details 
into a separate header, just as I suggested with examples given?  My very 
point was to avoid `#if MIPS_ISA_REV < 6' sprinkled throughout code.

 Also I note all the clobbers are the same across all the syscalls used 
here, so another possibility is to have a macro like VDSO_SYSCALL_CLOBBERS 
defined in a single place according to the architecture level, and then 
just use it throughout avoiding code duplication.

  Maciej