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@xxxxxxxxxxxxx>
Better put Arnd and linux-arch on cc...
Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> ---
> 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
