Re: [PATCH v1 06/15] powerpc: Remove address and errorcode arguments from do_break()

[Christophe Leroy]

Le 27/12/2020 à 04:25, Nicholas Piggin a écrit :
> Excerpts from Christophe Leroy's message of December 22, 2020 11:28 pm:
> > Let do_break() retrieve address and errorcode from regs.
> >
> > This simplifies the code and shouldn't impeed performance as
> > address and errorcode are likely still hot in the cache.
> >
> > Suggested-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> > ---
> >   arch/powerpc/include/asm/debug.h     | 3 +--
> >   arch/powerpc/kernel/exceptions-64s.S | 2 --
> >   arch/powerpc/kernel/head_8xx.S       | 5 -----
> >   arch/powerpc/kernel/process.c        | 8 +++-----
> >   4 files changed, 4 insertions(+), 14 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/debug.h b/arch/powerpc/include/asm/debug.h
> > index ec57daf87f40..0550eceab3ca 100644
> > --- a/arch/powerpc/include/asm/debug.h
> > +++ b/arch/powerpc/include/asm/debug.h
> > @@ -52,8 +52,7 @@ extern void do_send_trap(struct pt_regs *regs, unsigned long address,
> >   			 unsigned long error_code, int brkpt);
> >   #else
> >   
> > -extern void do_break(struct pt_regs *regs, unsigned long address,
> > -		     unsigned long error_code);
> > +void do_break(struct pt_regs *regs);
> >   #endif
> >   
> >   #endif /* _ASM_POWERPC_DEBUG_H */
> > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> > index cfbd1d690033..3ea067bcbb95 100644
> > --- a/arch/powerpc/kernel/exceptions-64s.S
> > +++ b/arch/powerpc/kernel/exceptions-64s.S
> > @@ -3262,8 +3262,6 @@ handle_page_fault:
> >   
> >   /* We have a data breakpoint exception - handle it */
> >   handle_dabr_fault:
> > -	ld      r4,_DAR(r1)
> > -	ld      r5,_DSISR(r1)
> >   	addi    r3,r1,STACK_FRAME_OVERHEAD
> >   	bl      do_break
> >   	/*
> > diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
> > index 52702f3db6df..81f3c984f50c 100644
> > --- a/arch/powerpc/kernel/head_8xx.S
> > +++ b/arch/powerpc/kernel/head_8xx.S
> > @@ -364,11 +364,6 @@ do_databreakpoint:
> >   	addi	r3,r1,STACK_FRAME_OVERHEAD
> >   	mfspr	r4,SPRN_BAR
> >   	stw	r4,_DAR(r11)
> > -#ifdef CONFIG_VMAP_STACK
> > -	lwz	r5,_DSISR(r11)
> > -#else
> > -	mfspr	r5,SPRN_DSISR
> > -#endif
>
> I didn't think you can do this (at leastuntil after your patch 10). I have my
> !VMAP path doing mfspr r5,DSISR ; stw r3,_DSISR(r11);

Yes you are right, I went too quick.

Christophe