linux-kernel - Re: [PATCH v6 0/8] powerpc/watchpoint: Bug fixes plus new feature flag

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Date:   Fri, 18 Sep 2020 20:50:49 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Rogerio Alves <rcardoso@...ux.ibm.com>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        christophe.leroy@....fr
Cc:     mikey@...ling.org, jniethe5@...il.com, pedromfc@...ux.ibm.com,
        linux-kernel@...r.kernel.org, paulus@...ba.org,
        rogealve@...ux.ibm.com, naveen.n.rao@...ux.vnet.ibm.com,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v6 0/8] powerpc/watchpoint: Bug fixes plus new feature flag

Rogerio Alves <rcardoso@...ux.ibm.com> writes:
> On 9/2/20 1:29 AM, Ravi Bangoria wrote:
>> Patch #1 fixes issue for quardword instruction on p10 predecessors.
>> Patch #2 fixes issue for vector instructions.
>> Patch #3 fixes a bug about watchpoint not firing when created with
>>           ptrace PPC_PTRACE_SETHWDEBUG and CONFIG_HAVE_HW_BREAKPOINT=N.
>>           The fix uses HW_BRK_TYPE_PRIV_ALL for ptrace user which, I
>>           guess, should be fine because we don't leak any kernel
>>           addresses and PRIV_ALL will also help to cover scenarios when
>>           kernel accesses user memory.
>> Patch #4,#5 fixes infinite exception bug, again the bug happens only
>>           with CONFIG_HAVE_HW_BREAKPOINT=N.
>> Patch #6 fixes two places where we are missing to set hw_len.
>> Patch #7 introduce new feature bit PPC_DEBUG_FEATURE_DATA_BP_ARCH_31
>>           which will be set when running on ISA 3.1 compliant machine.
>> Patch #8 finally adds selftest to test scenarios fixed by patch#2,#3
>>           and also moves MODE_EXACT tests outside of BP_RANGE condition.
>> 
>> Christophe, let me know if this series breaks something for 8xx.
>> 
>> v5: https://lore.kernel.org/r/20200825043617.1073634-1-ravi.bangoria@linux.ibm.com
>> 
>> v5->v6:
>>   - Fix build faulure reported by kernel test robot
>>   - patch #5. Use more compact if condition, suggested by Christophe
>> 
>> 
>> Ravi Bangoria (8):
>>    powerpc/watchpoint: Fix quarword instruction handling on p10
>>      predecessors
>>    powerpc/watchpoint: Fix handling of vector instructions
>>    powerpc/watchpoint/ptrace: Fix SETHWDEBUG when
>>      CONFIG_HAVE_HW_BREAKPOINT=N
>>    powerpc/watchpoint: Move DAWR detection logic outside of
>>      hw_breakpoint.c
>>    powerpc/watchpoint: Fix exception handling for
>>      CONFIG_HAVE_HW_BREAKPOINT=N
>>    powerpc/watchpoint: Add hw_len wherever missing
>>    powerpc/watchpoint/ptrace: Introduce PPC_DEBUG_FEATURE_DATA_BP_ARCH_31
>>    powerpc/watchpoint/selftests: Tests for kernel accessing user memory
>> 
>>   Documentation/powerpc/ptrace.rst              |   1 +
>>   arch/powerpc/include/asm/hw_breakpoint.h      |  12 ++
>>   arch/powerpc/include/uapi/asm/ptrace.h        |   1 +
>>   arch/powerpc/kernel/Makefile                  |   3 +-
>>   arch/powerpc/kernel/hw_breakpoint.c           | 149 +---------------
>>   .../kernel/hw_breakpoint_constraints.c        | 162 ++++++++++++++++++
>>   arch/powerpc/kernel/process.c                 |  48 ++++++
>>   arch/powerpc/kernel/ptrace/ptrace-noadv.c     |   9 +-
>>   arch/powerpc/xmon/xmon.c                      |   1 +
>>   .../selftests/powerpc/ptrace/ptrace-hwbreak.c |  48 +++++-
>>   10 files changed, 282 insertions(+), 152 deletions(-)
>>   create mode 100644 arch/powerpc/kernel/hw_breakpoint_constraints.c
>> 
>
> Tested this patch set for:
> - SETHWDEBUG when CONFIG_HAVE_HW_BREAKPOINT=N = OK
> - Fix exception handling for CONFIG_HAVE_HW_BREAKPOINT=N = OK
> - Check for PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 = OK
> - Fix quarword instruction handling on p10 predecessors = OK
> - Fix handling of vector instructions = OK
>
> Also tested for:
> - Set second watchpoint (P10 Mambo) = OK
> - Infinity loop on sc instruction = OK

Thanks.

I wasn't able to pick up your Tested-by tags as I'd already applied the
patches, but thanks for sending them anyway, they will live on in the
mailing list archives for eternity.

cheers