On Tue, 1 Dec 2015 17:00:59 -0800 Andi Kleen <a...@firstfloor.org> wrote:
> From: Andi Kleen <a...@linux.intel.com> > > For debugging low level code interacting with the CPU > it is often useful to trace the MSR read/writes. This gives > a concise summary of PMU and other operations. > > perf has an ad-hoc way to do this using trace_printk, > but it's somewhat limited (and also now spews ugly boot > messages when enabled) > > Instead define real trace points for all MSR accesses. > > This adds three new trace points: read_msr and write_msr > and rdpmc. > > They also report if the access faulted (if *_safe is used) > > This allows filtering and triggering on specific > MSR values, which allows various more advanced > debugging techniques. > > All the values are well defined in the CPU documentation. > > The trace can be post processed with > Documentation/trace/postprocess/decode_msr.py > to add symbolic MSR names to the trace. > > I only added it to native MSR accesses in C, not paravirtualized > or in entry*.S (which is not too interesting) > > Originally the patch kit moved the MSRs out of line. > This uses an alternative approach recommended by Steven Rostedt > of only moving the trace calls out of line, but open coding the > access to the jump label. > > v2: > Move MSR trace events to arch/x86/include/asm/msr-trace.h > Signed-off-by: Andi Kleen <a...@linux.intel.com> > For the general tracing part. Acked-by: Steven Rostedt <rost...@goodmis.org> -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
