linux-kernel - Re: [PATCH v2 4/4] uprobes/powerpc: Make use of generic routines to enable single step

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Message-ID: <50CFFAF7.6070406@in.ibm.com>
Date:	Tue, 18 Dec 2012 10:41:19 +0530
From:	"Suzuki K. Poulose" <suzuki@...ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	bigeasy@...utronix.de, ananth@...ibm.com,
	srikar@...ux.vnet.ibm.com, peterz@...radead.org,
	benh@...nel.crashing.org, mingo@...e.hu, anton@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] uprobes/powerpc: Make use of generic routines
 to enable single step

On 12/15/2012 01:32 AM, Oleg Nesterov wrote:
> On 12/03, Suzuki K. Poulose wrote:
>>
>> Replace the ptrace helpers with the powerpc generic routines to
>> enable/disable single step. We save/restore the MSR (and DCBR for BookE)
>> across for the operation. We don't have to disable the single step,
>> as restoring the MSR/DBCR would restore the previous state.
>
> Obviously I can't review this series (although it looks fine to me).
>
> Just one note,
>
>> @@ -121,7 +132,7 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
>>
>>   	WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
>>
>> -	uprobe_restore_context_sstep(&utask->autask);
>> +	uprobe_restore_context_sstep(&utask->autask, regs);
>
> I am not sure ppc needs this, but note that x86 does a bit more.
>
> Not only we need to restore the "single-step" state, we need to
> send SIGTRAP if it was not set by us. The same for _skip_sstep.
>
Ok. I will investigate that part and do the necessary.

Thanks
Suzuki

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