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Date: Wed, 6 Jun 2012 22:00:50 +0530
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 1/2] uprobes: Pass probed vaddr to
 arch_uprobe_analyze_insn()
Message-ID: <20120606163050.GB32094@linux.vnet.ibm.com>
References: <20120606091950.GB6745@in.ibm.com>
 <20120606150848.GA24641@redhat.com>
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Cc: peterz@infradead.org, lkml <linux-kernel@vger.kernel.org>,
 Paul Mackerras <paulus@samba.org>, Anton Blanchard <anton@samba.org>,
 Ingo Molnar <mingo@elte.hu>, linuxppc-dev@lists.ozlabs.org
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* Oleg Nesterov <oleg@redhat.com> [2012-06-06 17:08:48]:

> On 06/06, Ananth N Mavinakayanahalli wrote:
> >
> > From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> >
> > On RISC architectures like powerpc, instructions are fixed size.
> > Instruction analysis on such platforms is just a matter of (insn % 4).
> > Pass the vaddr at which the uprobe is to be inserted so that
> > arch_uprobe_analyze_insn() can flag misaligned registration requests.
> 
> And the next patch checks "vaddr & 0x03".
> 
> But why do you need this new arg? arch_uprobe_analyze_insn() could
> check "container_of(auprobe, struct uprobe, arch)->offset & 0x3" with
> the same effect, no? vm_start/vm_pgoff are obviously page-aligned.
> 

We cant use container_of because we moved the definition for struct
uprobe to kernel/events/uprobe.c. This was possible before when struct
uprobe definition was in include/uprobes.h 

-- 
Thanks and Regards
Srikar