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

[Dmitry V. Levin]

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?


-- 
ldv