perf_counter: powerpc: supply more precise information on counter overflow events

This uses values from the MMCRA, SIAR and SDAR registers on
powerpc to supply more precise information for overflow events,
including a data address when PERF_RECORD_ADDR is specified.

Since POWER6 uses different bit positions in MMCRA from earlier
processors, this converts the struct power_pmu limited_pmc5_6
field, which only had 0/1 values, into a flags field and
defines bit values for its previous use (PPMU_LIMITED_PMC5_6)
and a new flag (PPMU_ALT_SIPR) to indicate that the processor
uses the POWER6 bit positions rather than the earlier
positions.  It also adds definitions in reg.h for the new and
old positions of the bit that indicates that the SIAR and SDAR
values come from the same instruction.

For the data address, the SDAR value is supplied if we are not
doing instruction sampling.  In that case there is no guarantee
that the address given in the PERF_RECORD_ADDR subrecord will
correspond to the instruction whose address is given in the
PERF_RECORD_IP subrecord.

If instruction sampling is enabled (e.g. because this counter
is counting a marked instruction event), then we only supply
the SDAR value for the PERF_RECORD_ADDR subrecord if it
corresponds to the instruction whose address is in the
PERF_RECORD_IP subrecord.  Otherwise we supply 0.

[ Impact: support more PMU hardware features on PowerPC ]

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <18955.37028.48861.555309@drongo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 80 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c
index 8d4cafc84b82..6baae5a5c331 100644
--- a/arch/powerpc/kernel/perf_counter.c
+++ b/arch/powerpc/kernel/perf_counter.c
@@ -17,6 +17,7 @@
 #include <asm/pmc.h>
 #include <asm/machdep.h>
 #include <asm/firmware.h>
+#include <asm/ptrace.h>
 
 struct cpu_hw_counters {
 	int n_counters;
@@ -310,7 +311,8 @@ static void power_pmu_read(struct perf_counter *counter)
  */
 static int is_limited_pmc(int pmcnum)
 {
-	return ppmu->limited_pmc5_6 && (pmcnum == 5 || pmcnum == 6);
+	return (ppmu->flags & PPMU_LIMITED_PMC5_6)
+		&& (pmcnum == 5 || pmcnum == 6);
 }
 
 static void freeze_limited_counters(struct cpu_hw_counters *cpuhw,
@@ -860,7 +862,7 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
 	 * If this machine has limited counters, check whether this
 	 * event could go on a limited counter.
 	 */
-	if (ppmu->limited_pmc5_6) {
+	if (ppmu->flags & PPMU_LIMITED_PMC5_6) {
 		if (can_go_on_limited_pmc(counter, ev, flags)) {
 			flags |= PPMU_LIMITED_PMC_OK;
 		} else if (ppmu->limited_pmc_event(ev)) {
@@ -933,6 +935,7 @@ static void record_and_restart(struct perf_counter *counter, long val,
 	u64 period = counter->hw.irq_period;
 	s64 prev, delta, left;
 	int record = 0;
+	u64 addr, mmcra, sdsync;
 
 	/* we don't have to worry about interrupts here */
 	prev = atomic64_read(&counter->hw.prev_count);
@@ -963,8 +966,76 @@ static void record_and_restart(struct perf_counter *counter, long val,
 	/*
 	 * Finally record data if requested.
 	 */
-	if (record)
-		perf_counter_overflow(counter, nmi, regs, 0);
+	if (record) {
+		addr = 0;
+		if (counter->hw_event.record_type & PERF_RECORD_ADDR) {
+			/*
+			 * The user wants a data address recorded.
+			 * If we're not doing instruction sampling,
+			 * give them the SDAR (sampled data address).
+			 * If we are doing instruction sampling, then only
+			 * give them the SDAR if it corresponds to the
+			 * instruction pointed to by SIAR; this is indicated
+			 * by the [POWER6_]MMCRA_SDSYNC bit in MMCRA.
+			 */
+			mmcra = regs->dsisr;
+			sdsync = (ppmu->flags & PPMU_ALT_SIPR) ?
+				POWER6_MMCRA_SDSYNC : MMCRA_SDSYNC;
+			if (!(mmcra & MMCRA_SAMPLE_ENABLE) || (mmcra & sdsync))
+				addr = mfspr(SPRN_SDAR);
+		}
+		perf_counter_overflow(counter, nmi, regs, addr);
+	}
+}
+
+/*
+ * Called from generic code to get the misc flags (i.e. processor mode)
+ * for an event.
+ */
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+	unsigned long mmcra;
+
+	if (TRAP(regs) != 0xf00) {
+		/* not a PMU interrupt */
+		return user_mode(regs) ? PERF_EVENT_MISC_USER :
+			PERF_EVENT_MISC_KERNEL;
+	}
+
+	mmcra = regs->dsisr;
+	if (ppmu->flags & PPMU_ALT_SIPR) {
+		if (mmcra & POWER6_MMCRA_SIHV)
+			return PERF_EVENT_MISC_HYPERVISOR;
+		return (mmcra & POWER6_MMCRA_SIPR) ? PERF_EVENT_MISC_USER :
+			PERF_EVENT_MISC_KERNEL;
+	}
+	if (mmcra & MMCRA_SIHV)
+		return PERF_EVENT_MISC_HYPERVISOR;
+	return (mmcra & MMCRA_SIPR) ? PERF_EVENT_MISC_USER :
+			PERF_EVENT_MISC_KERNEL;
+}
+
+/*
+ * Called from generic code to get the instruction pointer
+ * for an event.
+ */
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+	unsigned long mmcra;
+	unsigned long ip;
+	unsigned long slot;
+
+	if (TRAP(regs) != 0xf00)
+		return regs->nip;	/* not a PMU interrupt */
+
+	ip = mfspr(SPRN_SIAR);
+	mmcra = regs->dsisr;
+	if ((mmcra & MMCRA_SAMPLE_ENABLE) && !(ppmu->flags & PPMU_ALT_SIPR)) {
+		slot = (mmcra & MMCRA_SLOT) >> MMCRA_SLOT_SHIFT;
+		if (slot > 1)
+			ip += 4 * (slot - 1);
+	}
+	return ip;
 }
 
 /*
@@ -984,6 +1055,11 @@ static void perf_counter_interrupt(struct pt_regs *regs)
 					mfspr(SPRN_PMC6));
 
 	/*
+	 * Overload regs->dsisr to store MMCRA so we only need to read it once.
+	 */
+	regs->dsisr = mfspr(SPRN_MMCRA);
+
+	/*
 	 * If interrupts were soft-disabled when this PMU interrupt
 	 * occurred, treat it as an NMI.
 	 */