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Date: Thu, 10 Oct 2019 11:30:27 +0200
From: Christophe Leroy <christophe.leroy@....fr>
To: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Cc: mpe@...erman.id.au, mikey@...ling.org, npiggin@...il.com,
benh@...nel.crashing.org, paulus@...ba.org,
naveen.n.rao@...ux.vnet.ibm.com, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/5] Powerpc/Watchpoint: Few important fixes
Le 10/10/2019 à 06:44, Ravi Bangoria a écrit :
>
>>> @Christophe, Is patch5 works for you on 8xx?
>>>
>>
>> Getting the following :
>>
>> root@...ip:~# ./ptrace-hwbreak
>> test: ptrace-hwbreak
>> tags: git_version:v5.4-rc2-710-gf0082e173fe4-dirty
>> 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: Fail
>> failure: ptrace-hwbreak
>>
>
> Thanks Christophe. I don't have any 8xx box. I checked qemu and it seems
> qemu emulation for 8xx is not yet supported. So I can't debug this. Can
> you please check why it's failing?
>
First issue: we get a mismatch between the parent and the child, because
len 8 test generates two reads/writes while the parent installs the
breakpoint only once.
Changing glvar from __u64 to unsigned long fixes the problem.
Then I get:
test: ptrace-hwbreak
tags: git_version:v5.4-rc2-710-gf0082e173fe4-dirty
PTRACE_SET_DEBUGREG, WO, len: 1: Ok
PTRACE_SET_DEBUGREG, WO, len: 2: Ok
PTRACE_SET_DEBUGREG, WO, len: 4: 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, RW, len: 1: Ok
PTRACE_SET_DEBUGREG, RW, len: 2: Ok
PTRACE_SET_DEBUGREG, RW, len: 4: 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: Fail
failure: ptrace-hwbreak
Which shows that PPC_PTRACE_SETHWDEBUG doesn't work in MODE_RANGE
Christophe
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