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

Dmitry V. Levin
2025-01-30T11:22:25Z

On Thu, Jan 30, 2025 at 09:33:03AM +0100, Sven Schnelle wrote:
> "Dmitry V. Levin" <ldv@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@strace.io>
> > Tested-by: Charlie Jenkins <charlie@rivosinc.com>
> > Reviewed-by: Charlie Jenkins <charlie@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?