Re: [RFC PATCH 12/25] kvx: Add system call support

[Arnd Bergmann]

On Tue, Jan 3, 2023, at 17:43, Yann Sionneau wrote:

> +
> +/*
> + * Ensure that the range [addr, addr+size) is within the process's
> + * address space
> + */
> +static inline int __access_ok(unsigned long addr, unsigned long size)
> +{
> +	return size <= TASK_SIZE && addr <= TASK_SIZE - size;
> +}

This is the same as the generic version, so just use that instead.

> +#define HAVE_GET_KERNEL_NOFAULT
> +
> +#define __get_kernel_nofault(dst, src, type, err_label)			\
> +do {									\
> +	long __kr_err;							\
> +									\
> +	__get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err);	\
> +	if (unlikely(__kr_err))						\
> +		goto err_label;						\
> +} while (0)
> +
> +#define __put_kernel_nofault(dst, src, type, err_label)			\
> +do {									\
> +	long __kr_err;							\
> +									\
> +	__put_user_nocheck(*((type *)(src)), (type *)(dst), __kr_err);	\
> +	if (unlikely(__kr_err))						\
> +		goto err_label;						\
> +} while (0)

The wrapper around __get_user_nocheck/__put_user_nocheck
is not ideal here. Since I think you only support new
compilers anyway, you can use the asm-goto-with-output feature
to define the asm to branch to the label directly, and use
the same thing to build __get_user()/__put_user().

> +++ b/arch/kvx/include/uapi/asm/unistd.h
> @@ -0,0 +1,16 @@

> +
> +#define __ARCH_WANT_RENAMEAT
> +#define __ARCH_WANT_NEW_STAT
> +#define __ARCH_WANT_SET_GET_RLIMIT
> +#define __ARCH_WANT_SYS_CLONE3

It's good to have clone3() but the other three sets
of syscalls should no longer be defined for new architectures,
so please remove those.

      Arnd