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 <npig...@gmail.com>
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
  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