Excerpts from Christophe Leroy's message of January 26, 2021 12:48 am:
> Only PPC64 has scv. No need to check the 0x7ff0 trap on PPC32.
>
> And ignore the scv parameter in syscall_exit_prepare (Save 14 cycles
> 346 => 332 cycles)
>
> Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
> ---
> arch/powerpc/kernel/entry_32.S | 1 -
> arch/powerpc/kernel/syscall.c | 7 +++++--
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
> index 9922a04650f7..6ae9c7bcb06c 100644
> --- a/arch/powerpc/kernel/entry_32.S
> +++ b/arch/powerpc/kernel/entry_32.S
> @@ -343,7 +343,6 @@ transfer_to_syscall:
>
> ret_from_syscall:
> addi r4,r1,STACK_FRAME_OVERHEAD
> - li r5,0
> bl syscall_exit_prepare
> #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
> /* If the process has its own DBCR0 value, load it up. The internal
> diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
> index 476909b11051..30f8a397a522 100644
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -86,7 +86,7 @@ notrace long system_call_exception(long r3, long r4, long
> r5,
> local_irq_enable();
>
> if (unlikely(current_thread_info()->flags & _TIF_SYSCALL_DOTRACE)) {
> - if (unlikely(regs->trap == 0x7ff0)) {
> + if (IS_ENABLED(CONFIG_PPC64) && unlikely(regs->trap == 0x7ff0))
> {
> /* Unsupported scv vector */
> _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
> return regs->gpr[3];
> @@ -109,7 +109,7 @@ notrace long system_call_exception(long r3, long r4, long
> r5,
> r8 = regs->gpr[8];
>
> } else if (unlikely(r0 >= NR_syscalls)) {
> - if (unlikely(regs->trap == 0x7ff0)) {
> + if (IS_ENABLED(CONFIG_PPC64) && unlikely(regs->trap == 0x7ff0))
> {
Perhaps this could be hidden behind a function like trap_is_scv()?
trap_is_unsupported_scv() ?
Thanks,
Nick
