Re: [PATCH v2 1/7] powerpc: properly negate error in syscall_set_return_value()

Alexey Gladkov
2025-01-14T13:00:22Z

On Mon, Jan 13, 2025 at 07:10:54PM +0200, Dmitry V. Levin wrote:
> Bring syscall_set_return_value() in sync with syscall_get_error(),
> and let upcoming ptrace/set_syscall_info selftest pass on powerpc.
>
> This reverts commit 1b1a3702a65c ("powerpc: Don't negate error in
> syscall_set_return_value()").
>
> Signed-off-by: Dmitry V. Levin <ldv@strace.io>
> ---
> arch/powerpc/include/asm/syscall.h | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
> index 3dd36c5e334a..422d7735ace6 100644
> --- a/arch/powerpc/include/asm/syscall.h
> +++ b/arch/powerpc/include/asm/syscall.h
> @@ -82,7 +82,11 @@ static inline void syscall_set_return_value(struct task_struct *task,
> */
> if (error) {
> regs->ccr |= 0x10000000L;
> - regs->gpr[3] = error;
> + /*
> + * In case of an error regs->gpr[3] contains
> + * a positive ERRORCODE.
> + */
> + regs->gpr[3] = -error;

After this change the syscall_get_error() will return positive value if
the system call failed. Since syscall_get_error() still believes
regs->gpr[3] is still positive in case !trap_is_scv().

Or am I missing something?

It looks like the selftest you mentioned in the commit message doesn't
check the !trap_is_scv() branch.

> } else {
> regs->ccr &= ~0x10000000L;
> regs->gpr[3] = val;
> --
> ldv

--
Rgrds, legion