Subject: Re: powerpc64/hw_breakpoints: Handle data breakpoints in radix mode

From: Michael Ellerman <[email-masked]>
Date: Mon, 19 Jun 2017 22:22:41 +1000 (AEST)

On Tue, 2017-06-13 at 18:42:00 UTC, "Naveen N. Rao" wrote:
> 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 <[email-masked]>
> Signed-off-by: Naveen N. Rao <[email-masked]>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/d89ba5353f301971dd7d2f9fdf25c4

cheers