linux-kernel - Re: [PATCH v5 10/13] powerpc/ptrace: split out ADV_DEBUG

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Date:   Sat, 21 Mar 2020 10:27:59 +0000
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>, mikey@...ling.org
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v5 10/13] powerpc/ptrace: split out ADV_DEBUG_REGS related
 functions.



On 03/20/2020 02:12 AM, Michael Ellerman wrote:
> Christophe Leroy <christophe.leroy@....fr> writes:
>> Move ADV_DEBUG_REGS functions out of ptrace.c, into
>> ptrace-adv.c and ptrace-noadv.c
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>> ---
>> v4: Leave hw_breakpoint.h for ptrace.c
>> ---
>>   arch/powerpc/kernel/ptrace/Makefile       |   4 +
>>   arch/powerpc/kernel/ptrace/ptrace-adv.c   | 468 ++++++++++++++++
>>   arch/powerpc/kernel/ptrace/ptrace-decl.h  |   5 +
>>   arch/powerpc/kernel/ptrace/ptrace-noadv.c | 236 ++++++++
>>   arch/powerpc/kernel/ptrace/ptrace.c       | 650 ----------------------
>>   5 files changed, 713 insertions(+), 650 deletions(-)
>>   create mode 100644 arch/powerpc/kernel/ptrace/ptrace-adv.c
>>   create mode 100644 arch/powerpc/kernel/ptrace/ptrace-noadv.c
> 
> This is somehow breaking the ptrace-hwbreak selftest on Power8:
> 
>    test: ptrace-hwbreak
>    tags: git_version:v5.6-rc6-892-g7a285a6067d6
>    PTRACE_SET_DEBUGREG, WO, len: 1: Ok
>    PTRACE_SET_DEBUGREG, WO, len: 2: Ok
>    PTRACE_SET_DEBUGREG, WO, len: 4: Ok
>    PTRACE_SET_DEBUGREG, WO, len: 8: Ok
>    PTRACE_SET_DEBUGREG, RO, len: 1: Ok
>    PTRACE_SET_DEBUGREG, RO, len: 2: Ok
>    PTRACE_SET_DEBUGREG, RO, len: 4: Ok
>    PTRACE_SET_DEBUGREG, RO, len: 8: Ok
>    PTRACE_SET_DEBUGREG, RW, len: 1: Ok
>    PTRACE_SET_DEBUGREG, RW, len: 2: Ok
>    PTRACE_SET_DEBUGREG, RW, len: 4: Ok
>    PTRACE_SET_DEBUGREG, RW, len: 8: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_EXACT, WO, len: 1: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_EXACT, RO, len: 1: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_EXACT, RW, len: 1: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_RANGE, DW ALIGNED, WO, len: 6: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_RANGE, DW ALIGNED, RO, len: 6: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_RANGE, DW ALIGNED, RW, len: 6: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_RANGE, DW UNALIGNED, WO, len: 6: Ok
>    PPC_PTRACE_SETHWDEBUG, MODE_RANGE, DW UNALIGNED, RO, len: 6: Fail
>    failure: ptrace-hwbreak
> 
> I haven't had time to work out why yet.
> 

A (big) part of commit c3f68b0478e7 ("powerpc/watchpoint: Fix ptrace 
code that muck around with address/len") was lost during rebase.

I'll send a fix, up to you to squash it in or commit it as is.

Christophe