Re: [PATCH 05/13] riscv: compat: syscall: Add compat_sys_call_table implementation

[Arnd Bergmann]

On Tue, Dec 21, 2021 at 5:35 PM <guoren@xxxxxxxxxx> wrote:
>
> From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
>
> Implement compat_syscall_table.c with compat_sys_call_table & fixup
> system call such as truncate64,pread64,fallocate which need two
> regs to indicate 64bit-arg (copied from arm64).
>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> ---
>  arch/riscv/include/asm/syscall.h         |  3 +
>  arch/riscv/kernel/compat_syscall_table.c | 84 ++++++++++++++++++++++++

Same here, I think most of these should go next to the actual syscalls, with the
duplicates removed from other platforms,

> +#define __SYSCALL_COMPAT
> +#undef __LP64__

What is the #undef for?

> +SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
> +       unsigned long, prot, unsigned long, flags,
> +       unsigned long, fd, unsigned long, offset)
> +{
> +       if ((prot & PROT_WRITE) && (prot & PROT_EXEC))
> +               if (unlikely(!(prot & PROT_READ)))
> +                       return -EINVAL;
> +
> +       return ksys_mmap_pgoff(addr, len, prot, flags, fd, offset);
> +}

This is one that we may have to deal with separately, introducing
sys_mmap_pgoff() was a mistake in my opinion, and we should just have
added a sys_mmap2() for all architectures that don't explicitly override it.

       Arnd