linux-kernel - Re: [PATCH v3 3/3] Powerpc64/Watchpoint: Rewrite ptrace-hwbreak.c selftest

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Date:   Wed, 4 Sep 2019 14:40:49 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Christophe Leroy <christophe.leroy@....fr>, mpe@...erman.id.au,
        mikey@...ling.org
Cc:     benh@...nel.crashing.org, paulus@...ba.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        npiggin@...il.com, naveen.n.rao@...ux.vnet.ibm.com,
        ravi.bangoria@...ux.ibm.com
Subject: Re: [PATCH v3 3/3] Powerpc64/Watchpoint: Rewrite ptrace-hwbreak.c
 selftest



On 8/28/19 11:44 AM, Christophe Leroy wrote:
> 
> 
> Le 10/07/2019 à 06:54, Ravi Bangoria a écrit :
>> ptrace-hwbreak.c selftest is logically broken. On powerpc, when
>> watchpoint is created with ptrace, signals are generated before
>> executing the instruction and user has to manually singlestep
>> the instruction with watchpoint disabled, which selftest never
>> does and thus it keeps on getting the signal at the same
>> instruction. If we fix it, selftest fails because the logical
>> connection between tracer(parent) and tracee(child) is also
>> broken. Rewrite the selftest and add new tests for unaligned
>> access.
> 
> On the 8xx, signals are generated after executing the instruction.
> 
> Can we make the test work in both case ?

Sure. I don't mind. I guess, it should be trivial to do that.

But I'm still waiting for Mikey / Mpe's replay on actual patches.
Mikey, mpe, is it ok to not ignore actual events but generate false 
positive events? Is there any other better approach?

Ravi