[PATCH V8 02/10] powerpc, perf: Restore privillege level filter support for BHRB

[Anshuman Khandual]

From: "khandual at linux.vnet.ibm.com" <khandual at linux.vnet.ibm.com>

'commit 9de5cb0f6df8 ("powerpc/perf: Add per-event excludes on Power8")'
broke the PMU based BHRB privilege level filter. BHRB depends on the
same MMCR0 bits for privilege level filter which was used to freeze all
the PMCs as a group. Once we moved to individual event based privilege
filters through MMCR2 register on POWER8, event associated privilege
filters are no longer applicable to the BHRB captured branches.

This patch solves the problem by restoring to the previous method of
privilege level filters for the event in case BHRB based branch stack
sampling is requested. This patch also changes 'check_excludes' for
the same reason.

Signed-off-by: Anshuman Khandual <khandual at linux.vnet.ibm.com>
---
 arch/powerpc/perf/core-book3s.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index c246e65..ae61629 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -930,7 +930,7 @@ static int power_check_constraints(struct cpu_hw_events *cpuhw,
  * added events.
  */
 static int check_excludes(struct perf_event **ctrs, unsigned int cflags[],
-			  int n_prev, int n_new)
+			  int n_prev, int n_new, int bhrb_users)
 {
 	int eu = 0, ek = 0, eh = 0;
 	int i, n, first;
@@ -941,7 +941,7 @@ static int check_excludes(struct perf_event **ctrs, unsigned int cflags[],
 	 * don't need to do any of this logic. NB. This assumes no PMU has both
 	 * per event exclude and limited PMCs.
 	 */
-	if (ppmu->flags & PPMU_ARCH_207S)
+	if ((ppmu->flags & PPMU_ARCH_207S) && !bhrb_users)
 		return 0;
 
 	n = n_prev + n_new;
@@ -1259,7 +1259,7 @@ static void power_pmu_enable(struct pmu *pmu)
 		goto out;
 	}
 
-	if (!(ppmu->flags & PPMU_ARCH_207S)) {
+	if (!(ppmu->flags & PPMU_ARCH_207S) || cpuhw->bhrb_users) {
 		/*
 		 * Add in MMCR0 freeze bits corresponding to the attr.exclude_*
 		 * bits for the first event. We have already checked that all
@@ -1284,7 +1284,7 @@ static void power_pmu_enable(struct pmu *pmu)
 	mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
 	mtspr(SPRN_MMCR0, (cpuhw->mmcr[0] & ~(MMCR0_PMC1CE | MMCR0_PMCjCE))
 				| MMCR0_FC);
-	if (ppmu->flags & PPMU_ARCH_207S)
+	if ((ppmu->flags & PPMU_ARCH_207S) && !cpuhw->bhrb_users)
 		mtspr(SPRN_MMCR2, cpuhw->mmcr[3]);
 
 	/*
@@ -1436,7 +1436,8 @@ static int power_pmu_add(struct perf_event *event, int ef_flags)
 	if (cpuhw->group_flag & PERF_EVENT_TXN)
 		goto nocheck;
 
-	if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
+	if (check_excludes(cpuhw->event, cpuhw->flags,
+				n0, 1, cpuhw->bhrb_users))
 		goto out;
 	if (power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n0 + 1))
 		goto out;
@@ -1615,7 +1616,7 @@ static int power_pmu_commit_txn(struct pmu *pmu)
 		return -EAGAIN;
 	cpuhw = this_cpu_ptr(&cpu_hw_events);
 	n = cpuhw->n_events;
-	if (check_excludes(cpuhw->event, cpuhw->flags, 0, n))
+	if (check_excludes(cpuhw->event, cpuhw->flags, 0, n, cpuhw->bhrb_users))
 		return -EAGAIN;
 	i = power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n);
 	if (i < 0)
@@ -1828,10 +1829,12 @@ static int power_pmu_event_init(struct perf_event *event)
 	events[n] = ev;
 	ctrs[n] = event;
 	cflags[n] = flags;
-	if (check_excludes(ctrs, cflags, n, 1))
+	cpuhw = &get_cpu_var(cpu_hw_events);
+	if (check_excludes(ctrs, cflags, n, 1, cpuhw->bhrb_users)) {
+		put_cpu_var(cpu_hw_events);
 		return -EINVAL;
+	}
 
-	cpuhw = &get_cpu_var(cpu_hw_events);
 	err = power_check_constraints(cpuhw, events, cflags, n + 1);
 
 	if (has_branch_stack(event)) {
-- 
2.1.0