[PATCH V4 08/17] riscv: compat: syscall: Add compat_sys_call_table implementation

[Guo Ren]

On Sun, Jan 30, 2022 at 6:41 AM Arnd Bergmann <arnd at arndb.de> wrote:
>
> > Implement compat sys_call_table and some system call functions:
> > truncate64, ftruncate64, fallocate, pread64, pwrite64,
> > sync_file_range, readahead, fadvise64_64 which need argument
> > translation.
> >
> > Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren at kernel.org>
> > Cc: Arnd Bergmann <arnd at arndb.de>
>
> This all looks really good, but I would change one detail:
>
> > +#ifndef compat_arg_u64
> > +#define compat_arg_u64(name)           u32  name##_lo, u32  name##_hi
> > +#define compat_arg_u64_dual(name)      u32, name##_lo, u32, name##_hi
> > +#define compat_arg_u64_glue(name)      (((u64)name##_hi << 32) | \
> > +                                        ((u64)name##_lo & 0xffffffffUL))
> > +#endif
>
> I would make these endian-specific, and reverse them on big-endian
> architectures. That way it
> should be possible to share them across all compat architectures
> without needing the override
> option.
I hope it could be another patch. Because it's not clear to
_LITTLE_ENDIAN definition in archs.

eg: Names could be __ORDER_LITTLE_ENDIAN__ CPU_LITTLE_ENDIAN
SYS_SUPPORTS_LITTLE_ENDIAN __LITTLE_ENDIAN

riscv is little-endian, but no any LITTLE_ENDIAN definition.

So let's keep them in the patch, first, Thx

>
>         Arnd



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/