Messages in this thread | | | Date | Mon, 14 Nov 2022 11:51:09 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] perf/x86/intel/pt: Fix sampling using single range output |
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On Sat, Nov 12, 2022 at 05:15:08PM +0200, Adrian Hunter wrote: > Deal with errata TGL052, ADL037 and RPL017 "Trace May Contain Incorrect > Data When Configured With Single Range Output Larger Than 4KB" by > disabling single range output whenever larger than 4KB. > > Fixes: 670638477aed ("perf/x86/intel/pt: Opportunistically use single range output mode") > Cc: stable@vger.kernel.org > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > --- > arch/x86/events/intel/pt.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c > index 82ef87e9a897..42a55794004a 100644 > --- a/arch/x86/events/intel/pt.c > +++ b/arch/x86/events/intel/pt.c > @@ -1263,6 +1263,15 @@ static int pt_buffer_try_single(struct pt_buffer *buf, int nr_pages) > if (1 << order != nr_pages) > goto out; > > + /* > + * Some processors cannot always support single range for more than > + * 4KB - refer errata TGL052, ADL037 and RPL017. Future processors might > + * also be affected, so for now rather than trying to keep track of > + * which ones, just disable it for all. > + */ > + if (nr_pages > 1) > + goto out;
This effectively declares single-output-mode dead? Because I don't think anybody uses PT with a single 4K buffer.
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