[PATCH v3 2/6] syscall.h: add syscall_set_arguments() and syscall_set_return_value()

[Sven Schnelle]

"Dmitry V. Levin" <ldv at strace.io> writes:

> These functions are going to be needed on all HAVE_ARCH_TRACEHOOK
> architectures to implement PTRACE_SET_SYSCALL_INFO API.
>
> This partially reverts commit 7962c2eddbfe ("arch: remove unused
> function syscall_set_arguments()") by reusing some of old
> syscall_set_arguments() implementations.
>
> Signed-off-by: Dmitry V. Levin <ldv at strace.io>
> Tested-by: Charlie Jenkins <charlie at rivosinc.com>
> Reviewed-by: Charlie Jenkins <charlie at rivosinc.com>
> ---
>  arch/arc/include/asm/syscall.h        | 14 +++++++++++
>  arch/arm/include/asm/syscall.h        | 13 ++++++++++
>  arch/arm64/include/asm/syscall.h      | 13 ++++++++++
>  arch/csky/include/asm/syscall.h       | 13 ++++++++++
>  arch/hexagon/include/asm/syscall.h    | 14 +++++++++++
>  arch/loongarch/include/asm/syscall.h  |  8 ++++++
>  arch/mips/include/asm/syscall.h       | 32 ++++++++++++++++++++++++
>  arch/nios2/include/asm/syscall.h      | 11 ++++++++
>  arch/openrisc/include/asm/syscall.h   |  7 ++++++
>  arch/parisc/include/asm/syscall.h     | 12 +++++++++
>  arch/powerpc/include/asm/syscall.h    | 10 ++++++++
>  arch/riscv/include/asm/syscall.h      |  9 +++++++
>  arch/s390/include/asm/syscall.h       | 12 +++++++++
>  arch/sh/include/asm/syscall_32.h      | 12 +++++++++
>  arch/sparc/include/asm/syscall.h      | 10 ++++++++
>  arch/um/include/asm/syscall-generic.h | 14 +++++++++++
>  arch/x86/include/asm/syscall.h        | 36 +++++++++++++++++++++++++++
>  arch/xtensa/include/asm/syscall.h     | 11 ++++++++
>  include/asm-generic/syscall.h         | 16 ++++++++++++
>  19 files changed, 267 insertions(+)
>
> diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
> index 27e3d804b311..b3dd883699e7 100644
> --- a/arch/s390/include/asm/syscall.h
> +++ b/arch/s390/include/asm/syscall.h
> @@ -78,6 +78,18 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	args[0] = regs->orig_gpr2 & mask;
>  }
>  
> +static inline void syscall_set_arguments(struct task_struct *task,
> +					 struct pt_regs *regs,
> +					 const unsigned long *args)
> +{
> +	unsigned int n = 6;
> +
> +	while (n-- > 0)
> +		if (n > 0)
> +			regs->gprs[2 + n] = args[n];
> +	regs->orig_gpr2 = args[0];
> +}

Could that be changed to something like:

for (int n = 1; n < 6; n++)
        regs->gprs[2 + n] = args[n];
regs->orig_gpr2 = args[0];

I think this is way easier to parse.