[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:

> On Thu, Jan 30, 2025 at 09:33:03AM +0100, Sven Schnelle wrote:
>> "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.
>
> I don't mind changing syscall_set_arguments() this way, but it just
> mirrors syscall_get_arguments(), so I think it would be better if these
> two functions were written in the same style.  Would you like to change
> syscall_get_arguments() as well?

Oh. I'll prepare a patch for syscall_get_arguments(), wasn't aware
that this function looks the same. I'll send this via the s390 tree, so
it's independent of your patch series. Thanks!