[RFC Patch 1/2] PPC64-HWBKPT: Disable interrupts for data breakpoint exceptions
Paul Mackerras
paulus at samba.org
Tue Mar 30 16:24:42 EST 2010
On Tue, Mar 23, 2010 at 07:37:02PM +0530, K.Prasad wrote:
> Index: linux-2.6.ppc64_test/arch/powerpc/kernel/exceptions-64s.S
> ===================================================================
> --- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/exceptions-64s.S
> +++ linux-2.6.ppc64_test/arch/powerpc/kernel/exceptions-64s.S
> @@ -735,6 +735,9 @@ _STATIC(do_hash_page)
> std r3,_DAR(r1)
> std r4,_DSISR(r1)
>
> + andis. r0,r4,0x0040 /* Data Address Breakpoint match? */
Minor comment: why not DSISR_DABRMATCH at h instead of 0x0040?
> + bne- handle_dabr_fault
> +
> andis. r0,r4,0xa450 /* weird error? */
> bne- handle_page_fault /* if not, try to insert a HPTE */
> BEGIN_FTR_SECTION
> @@ -823,6 +826,15 @@ END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISER
> bl .raw_local_irq_restore
> b 11f
>
> +/* We have a data breakpoint exception - handle it */
> +handle_dabr_fault:
> + /* Populate the pt_regs structure */
Another minor comment: that comment isn't accurate since you're not
putting anything in the pt_regs, just getting arguments to do_dabr
from it.
> + ld r4,_DAR(r1)
> + ld r5,_DSISR(r1)
> + addi r3,r1,STACK_FRAME_OVERHEAD
> + bl .do_dabr
> + b .ret_from_except_lite
> +
> /* Here we have a page fault that hash_page can't handle. */
> handle_page_fault:
> ENABLE_INTS
> Index: linux-2.6.ppc64_test/arch/powerpc/mm/fault.c
> ===================================================================
> --- linux-2.6.ppc64_test.orig/arch/powerpc/mm/fault.c
> +++ linux-2.6.ppc64_test/arch/powerpc/mm/fault.c
> @@ -151,7 +151,7 @@ int __kprobes do_page_fault(struct pt_re
> if (!user_mode(regs) && (address >= TASK_SIZE))
> return SIGSEGV;
>
> -#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
> +#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || defined(CONFIG_PPC64))
If we added similar code to head_32.S, we could probably remove this
whole ifdef block. But that can be done in a later patch.
Paul.
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