db278b90c3
For Intel LBR, the LBR Top-of-Stack (TOS) information is the HW index of raw branch record for the most recent branch. For non-adaptive PEBS and non-PEBS, the TOS information can be directly retrieved from TOS MSR read in intel_pmu_lbr_read(). For adaptive PEBS, the LBR information stored in PEBS record doesn't include the TOS information. For single PEBS, TOS can be directly read from MSR, because the PMI is triggered immediately after PEBS is written. TOS MSR is still unchanged. For large PEBS, TOS MSR has stale value. Set -1ULL to indicate that the TOS information is not available. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200127165355.27495-3-kan.liang@linux.intel.com