Messages in this thread | | | Date | Wed, 27 Mar 2013 15:34:37 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH v7 11/18] perf tools: add mem access sampling core support |
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On Wed, Mar 27, 2013 at 03:20:14PM +0100, Peter Zijlstra wrote: > On Wed, 2013-03-27 at 15:14 +0100, Jiri Olsa wrote: > > we have correct cpumode for sample->ip, but I think it's the > > PEBS->dla (sample->addr) where we need to guess.. right? > > kernel mode very much fakes the cpumode/segment stuff for PEBS. PEBS > assumes you're running in a linear/flat mode. >
say we hit the sample when kernel accesses the user data, we will endup with IP in kernel space and DATA ptr in user space.. in theory ;-)
and that would need the cpumode guessing for DATA ptr, because cpumode value is deduced from cs register
jirka
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