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Date: Wed, 10 Jul 2019 12:08:36 +0530 From: Ravi Bangoria <ravi.bangoria@...ux.ibm.com> To: Christophe Leroy <christophe.leroy@....fr> Cc: mpe@...erman.id.au, mikey@...ling.org, 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 <ravi.bangoria@...ux.ibm.com> Subject: Re: [PATCH v3 2/3] Powerpc64/Watchpoint: Don't ignore extraneous exceptions On 7/10/19 11:57 AM, Christophe Leroy wrote: > > > Le 10/07/2019 à 06:54, Ravi Bangoria a écrit : >> On Powerpc64, watchpoint match range is double-word granular. On >> a watchpoint hit, DAR is set to the first byte of overlap between >> actual access and watched range. And thus it's quite possible that >> DAR does not point inside user specified range. Ex, say user creates >> a watchpoint with address range 0x1004 to 0x1007. So hw would be >> configured to watch from 0x1000 to 0x1007. If there is a 4 byte >> access from 0x1002 to 0x1005, DAR will point to 0x1002 and thus >> interrupt handler considers it as extraneous, but it's actually not, >> because part of the access belongs to what user has asked. So, let >> kernel pass it on to user and let user decide what to do with it >> instead of silently ignoring it. The drawback is, it can generate >> false positive events. > > Why adding some #ifdefs based on CONFIG_8xx ? I don't know how 8xx behaves so I'm keeping the current behavior(ignore extraneous exception) for 8xx. > > I see your commit log mentions 'Powerpc64'. What about BOOK3S/32 ? Hmm, I should not have mention 64 there. Yes, the change should cover both Books3S/64 and Book3S/32.
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