"Naveen N. Rao" <naveen.n....@linux.vnet.ibm.com> writes:
> On P9, trying to use data breakpoints throws the splat shown below (*).
> This is because the check for a data breakpoint in DSISR is in
> do_hash_page(). Move this check to handle_page_fault() so as to catch
> data breakpoints in both hash and radix MMU modes.
>
> While at it, also remove the label '11' that was made redundant by
> commit a546498f3bf9aa ("powerpc: Call do_page_fault() with interrupts
> off")
>
> (*)
> Unable to handle kernel paging request for data at address
> 0xc000000000e19218
> Faulting instruction address: 0xc0000000001155e8
> cpu 0x0: Vector: 300 (Data Access) at [c0000000ef1e7b20]
> pc: c0000000001155e8: find_pid_ns+0x48/0xe0
> lr: c000000000116ac4: find_task_by_vpid+0x44/0x90
> sp: c0000000ef1e7da0
> msr: 9000000000009033
> dar: c000000000e19218
> dsisr: 400000
> current = 0xc0000000f1f59700
> paca = 0xc00000000fd40000 softe: 0 irq_happened: 0x01
> pid = 1192, comm = sh
> Linux version 4.12.0-rc3-nnr (root@ea605ec2993c) (gcc version 5.4.0
> 20160609 (Ubuntu/IBM 5.4.0-6ubuntu1~16.04.1) ) #74 SMP Tue Jun 13 16:52:49
> UTC 2017
> enter ? for help
> [c0000000ef1e7dc0] c000000000116ac4 find_task_by_vpid+0x44/0x90
> [c0000000ef1e7de0] c000000000108800 SyS_setpgid+0x80/0x220
> [c0000000ef1e7e30] c00000000000ba6c system_call+0x38/0xfc
> --- Exception: c01 (System Call) at 00007fff94480890
> SP (7fffd91e7260) is in userspace
>
> Fixes: caca285e5ab4a ("powerpc/mm/radix: Use STD_MMU_64 to properly
> isolate hash related code")
> Reported-by: Shriya R. Kulkarni <shriy...@in.ibm.com>
> Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
> ---
> arch/powerpc/kernel/exceptions-64s.S | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S
> b/arch/powerpc/kernel/exceptions-64s.S
> index ae418b85c17c..17ee701b8336 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1411,10 +1411,8 @@ USE_TEXT_SECTION()
> .balign IFETCH_ALIGN_BYTES
> do_hash_page:
> #ifdef CONFIG_PPC_STD_MMU_64
> - andis. r0,r4,0xa410 /* weird error? */
> + andis. r0,r4,0xa450 /* weird error? */
Can we convert that to a #define value. Ram did try to do that here.
https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-June/158607.html
> bne- handle_page_fault /* if not, try to insert a HPTE */
> - andis. r0,r4,DSISR_DABRMATCH@h
> - bne- handle_dabr_fault
> CURRENT_THREAD_INFO(r11, r1)
> lwz r0,TI_PREEMPT(r11) /* If we're in an "NMI" */
> andis. r0,r0,NMI_MASK@h /* (i.e. an irq when soft-disabled) */
> @@ -1442,7 +1440,9 @@ do_hash_page:
>
> /* Here we have a page fault that hash_page can't handle. */
> handle_page_fault:
> -11: ld r4,_DAR(r1)
> + andis. r0,r4,DSISR_DABRMATCH@h
> + bne- handle_dabr_fault
> + ld r4,_DAR(r1)
> ld r5,_DSISR(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> bl do_page_fault
> --
> 2.12.2
-aneesh
