Re: [PATCH 2/3] arm64: syscall.h: Add sign extension handling in syscall_get_return_value for compat

[Oleg Nesterov]

On 04/16, He Zhe wrote:
>
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -44,7 +44,12 @@ static inline long syscall_get_error(struct task_struct *task,
>  static inline long syscall_get_return_value(struct task_struct *task,
>  					    struct pt_regs *regs)
>  {
> -	return regs->regs[0];
> +	long val = regs->regs[0];
> +
> +	if (is_compat_thread(task_thread_info(task)))
> +		val = sign_extend64(val, 31);
> +
> +	return val;
>  }

I can't really review these arm-specific patches, but with this change both
syscall_get_error() and is_syscall_success() can use syscall_get_return_value()
to avoid the code duplication.

Oleg.