Re: [PATCH 09/23] asm-generic: compat: Support BE for long long args in 32-bit ABIs

["Nicholas Piggin" <npiggin@gmail.com>]

On Fri Sep 16, 2022 at 3:32 PM AEST, Rohan McLure wrote:
> 32-bit ABIs support passing 64-bit integers by registers via argument
> translation. Commit 59c10c52f573 ("riscv: compat: syscall: Add
> compat_sys_call_table implementation") implements the compat_arg_u64
> macro for efficiently defining little endian compatibility syscalls.
>
> Architectures supporting big endianness may benefit from reciprocal
> argument translation, but are welcome also to implement their own.
>
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>

Better put Arnd and linux-arch on cc...

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

> ---
> V4 -> V5: New patch.
> ---
>  include/asm-generic/compat.h | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/include/asm-generic/compat.h b/include/asm-generic/compat.h
> index d06308a2a7a8..aeb257ad3d1a 100644
> --- a/include/asm-generic/compat.h
> +++ b/include/asm-generic/compat.h
> @@ -14,12 +14,17 @@
>  #define COMPAT_OFF_T_MAX	0x7fffffff
>  #endif
>  
> -#if !defined(compat_arg_u64) && !defined(CONFIG_CPU_BIG_ENDIAN)
> +#ifndef compat_arg_u64
> +#ifdef CONFIG_CPU_BIG_ENDIAN
>  #define compat_arg_u64(name)		u32  name##_lo, u32  name##_hi
>  #define compat_arg_u64_dual(name)	u32, name##_lo, u32, name##_hi
> +#else
> +#define compat_arg_u64(name)		u32  name##_hi, u32  name##_lo
> +#define compat_arg_u64_dual(name)	u32, name##_hi, u32, name##_lo
> +#endif
>  #define compat_arg_u64_glue(name)	(((u64)name##_lo & 0xffffffffUL) | \
>  					 ((u64)name##_hi << 32))
> -#endif
> +#endif /* compat_arg_u64 */
>  
>  /* These types are common across all compat ABIs */
>  typedef u32 compat_size_t;
> -- 
> 2.34.1