Date: Fri, 16 Jun 2017 12:10:41 -0700
From: Ram Pai <linuxram@us.ibm.com>
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        dave.hansen@intel.com, paulus@samba.org,
        aneesh.kumar@linux.vnet.ibm.com
Subject: Re: [RFC PATCH 7/7 v1]powerpc: Deliver SEGV signal on protection key
 violation.
Reply-To: Ram Pai <linuxram@us.ibm.com>
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On Fri, Jun 16, 2017 at 02:50:13PM +0530, Anshuman Khandual wrote:
> On 06/06/2017 06:35 AM, Ram Pai wrote:
> > The value of the AMR register at the time of the exception
> > is made available in gp_regs[PT_AMR] of the siginfo.
> 
> But its already available there in uctxt->uc_mcontext.regs->amr
> while inside the signal delivery context in the user space. The
> pt_regs already got updated with new AMR register. Then why we
> need gp_regs to also contain AMR as well ?

It should not be available in uctxt->uc_mcontext.regs->amr.
In fact that field itself should not be there.

The ideas was to use one of the unused fields in gp_regs; without
extending gp_regs, to provide the contents of AMR. the 
PT_AMR offset in gp_regs is currently not used, which I am using
in this patch.

However this patch needs to be modified not to extend pt_regs,
or uctxt->uc_mcontext.regs

Thanks for initiating this concern.
RP

-- 
Ram Pai