Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

1 files changed, 1318 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c
new file mode 100644
index 000000000000..87f1663584b0
--- /dev/null
+++ b/arch/powerpc/kernel/perf_event.c
@@ -0,0 +1,1318 @@
+/*
+ * Performance event support - powerpc architecture code
+ *
+ * Copyright 2008-2009 Paul Mackerras, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_event.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <asm/reg.h>
+#include <asm/pmc.h>
+#include <asm/machdep.h>
+#include <asm/firmware.h>
+#include <asm/ptrace.h>
+
+struct cpu_hw_events {
+	int n_events;
+	int n_percpu;
+	int disabled;
+	int n_added;
+	int n_limited;
+	u8  pmcs_enabled;
+	struct perf_event *event[MAX_HWEVENTS];
+	u64 events[MAX_HWEVENTS];
+	unsigned int flags[MAX_HWEVENTS];
+	unsigned long mmcr[3];
+	struct perf_event *limited_counter[MAX_LIMITED_HWCOUNTERS];
+	u8  limited_hwidx[MAX_LIMITED_HWCOUNTERS];
+	u64 alternatives[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
+	unsigned long amasks[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
+	unsigned long avalues[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
+};
+DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
+
+struct power_pmu *ppmu;
+
+/*
+ * Normally, to ignore kernel events we set the FCS (freeze counters
+ * in supervisor mode) bit in MMCR0, but if the kernel runs with the
+ * hypervisor bit set in the MSR, or if we are running on a processor
+ * where the hypervisor bit is forced to 1 (as on Apple G5 processors),
+ * then we need to use the FCHV bit to ignore kernel events.
+ */
+static unsigned int freeze_events_kernel = MMCR0_FCS;
+
+/*
+ * 32-bit doesn't have MMCRA but does have an MMCR2,
+ * and a few other names are different.
+ */
+#ifdef CONFIG_PPC32
+
+#define MMCR0_FCHV		0
+#define MMCR0_PMCjCE		MMCR0_PMCnCE
+
+#define SPRN_MMCRA		SPRN_MMCR2
+#define MMCRA_SAMPLE_ENABLE	0
+
+static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
+{
+	return 0;
+}
+static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp) { }
+static inline u32 perf_get_misc_flags(struct pt_regs *regs)
+{
+	return 0;
+}
+static inline void perf_read_regs(struct pt_regs *regs) { }
+static inline int perf_intr_is_nmi(struct pt_regs *regs)
+{
+	return 0;
+}
+
+#endif /* CONFIG_PPC32 */
+
+/*
+ * Things that are specific to 64-bit implementations.
+ */
+#ifdef CONFIG_PPC64
+
+static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
+{
+	unsigned long mmcra = regs->dsisr;
+
+	if ((mmcra & MMCRA_SAMPLE_ENABLE) && !(ppmu->flags & PPMU_ALT_SIPR)) {
+		unsigned long slot = (mmcra & MMCRA_SLOT) >> MMCRA_SLOT_SHIFT;
+		if (slot > 1)
+			return 4 * (slot - 1);
+	}
+	return 0;
+}
+
+/*
+ * 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.
+ */
+static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp)
+{
+	unsigned long mmcra = regs->dsisr;
+	unsigned long sdsync = (ppmu->flags & PPMU_ALT_SIPR) ?
+		POWER6_MMCRA_SDSYNC : MMCRA_SDSYNC;
+
+	if (!(mmcra & MMCRA_SAMPLE_ENABLE) || (mmcra & sdsync))
+		*addrp = mfspr(SPRN_SDAR);
+}
+
+static inline u32 perf_get_misc_flags(struct pt_regs *regs)
+{
+	unsigned long mmcra = regs->dsisr;
+	unsigned long sihv = MMCRA_SIHV;
+	unsigned long sipr = MMCRA_SIPR;
+
+	if (TRAP(regs) != 0xf00)
+		return 0;	/* not a PMU interrupt */
+
+	if (ppmu->flags & PPMU_ALT_SIPR) {
+		sihv = POWER6_MMCRA_SIHV;
+		sipr = POWER6_MMCRA_SIPR;
+	}
+
+	/* PR has priority over HV, so order below is important */
+	if (mmcra & sipr)
+		return PERF_RECORD_MISC_USER;
+	if ((mmcra & sihv) && (freeze_events_kernel != MMCR0_FCHV))
+		return PERF_RECORD_MISC_HYPERVISOR;
+	return PERF_RECORD_MISC_KERNEL;
+}
+
+/*
+ * Overload regs->dsisr to store MMCRA so we only need to read it once
+ * on each interrupt.
+ */
+static inline void perf_read_regs(struct pt_regs *regs)
+{
+	regs->dsisr = mfspr(SPRN_MMCRA);
+}
+
+/*
+ * If interrupts were soft-disabled when a PMU interrupt occurs, treat
+ * it as an NMI.
+ */
+static inline int perf_intr_is_nmi(struct pt_regs *regs)
+{
+	return !regs->softe;
+}
+
+#endif /* CONFIG_PPC64 */
+
+static void perf_event_interrupt(struct pt_regs *regs);
+
+void perf_event_print_debug(void)
+{
+}
+
+/*
+ * Read one performance monitor counter (PMC).
+ */
+static unsigned long read_pmc(int idx)
+{
+	unsigned long val;
+
+	switch (idx) {
+	case 1:
+		val = mfspr(SPRN_PMC1);
+		break;
+	case 2:
+		val = mfspr(SPRN_PMC2);
+		break;
+	case 3:
+		val = mfspr(SPRN_PMC3);
+		break;
+	case 4:
+		val = mfspr(SPRN_PMC4);
+		break;
+	case 5:
+		val = mfspr(SPRN_PMC5);
+		break;
+	case 6:
+		val = mfspr(SPRN_PMC6);
+		break;
+#ifdef CONFIG_PPC64
+	case 7:
+		val = mfspr(SPRN_PMC7);
+		break;
+	case 8:
+		val = mfspr(SPRN_PMC8);
+		break;
+#endif /* CONFIG_PPC64 */
+	default:
+		printk(KERN_ERR "oops trying to read PMC%d\n", idx);
+		val = 0;
+	}
+	return val;
+}
+
+/*
+ * Write one PMC.
+ */
+static void write_pmc(int idx, unsigned long val)
+{
+	switch (idx) {
+	case 1:
+		mtspr(SPRN_PMC1, val);
+		break;
+	case 2:
+		mtspr(SPRN_PMC2, val);
+		break;
+	case 3:
+		mtspr(SPRN_PMC3, val);
+		break;
+	case 4:
+		mtspr(SPRN_PMC4, val);
+		break;
+	case 5:
+		mtspr(SPRN_PMC5, val);
+		break;
+	case 6:
+		mtspr(SPRN_PMC6, val);
+		break;
+#ifdef CONFIG_PPC64
+	case 7:
+		mtspr(SPRN_PMC7, val);
+		break;
+	case 8:
+		mtspr(SPRN_PMC8, val);
+		break;
+#endif /* CONFIG_PPC64 */
+	default:
+		printk(KERN_ERR "oops trying to write PMC%d\n", idx);
+	}
+}
+
+/*
+ * Check if a set of events can all go on the PMU at once.
+ * If they can't, this will look at alternative codes for the events
+ * and see if any combination of alternative codes is feasible.
+ * The feasible set is returned in event_id[].
+ */
+static int power_check_constraints(struct cpu_hw_events *cpuhw,
+				   u64 event_id[], unsigned int cflags[],
+				   int n_ev)
+{
+	unsigned long mask, value, nv;
+	unsigned long smasks[MAX_HWEVENTS], svalues[MAX_HWEVENTS];
+	int n_alt[MAX_HWEVENTS], choice[MAX_HWEVENTS];
+	int i, j;
+	unsigned long addf = ppmu->add_fields;
+	unsigned long tadd = ppmu->test_adder;
+
+	if (n_ev > ppmu->n_counter)
+		return -1;
+
+	/* First see if the events will go on as-is */
+	for (i = 0; i < n_ev; ++i) {
+		if ((cflags[i] & PPMU_LIMITED_PMC_REQD)
+		    && !ppmu->limited_pmc_event(event_id[i])) {
+			ppmu->get_alternatives(event_id[i], cflags[i],
+					       cpuhw->alternatives[i]);
+			event_id[i] = cpuhw->alternatives[i][0];
+		}
+		if (ppmu->get_constraint(event_id[i], &cpuhw->amasks[i][0],
+					 &cpuhw->avalues[i][0]))
+			return -1;
+	}
+	value = mask = 0;
+	for (i = 0; i < n_ev; ++i) {
+		nv = (value | cpuhw->avalues[i][0]) +
+			(value & cpuhw->avalues[i][0] & addf);
+		if ((((nv + tadd) ^ value) & mask) != 0 ||
+		    (((nv + tadd) ^ cpuhw->avalues[i][0]) &
+		     cpuhw->amasks[i][0]) != 0)
+			break;
+		value = nv;
+		mask |= cpuhw->amasks[i][0];
+	}
+	if (i == n_ev)
+		return 0;	/* all OK */
+
+	/* doesn't work, gather alternatives... */
+	if (!ppmu->get_alternatives)
+		return -1;
+	for (i = 0; i < n_ev; ++i) {
+		choice[i] = 0;
+		n_alt[i] = ppmu->get_alternatives(event_id[i], cflags[i],
+						  cpuhw->alternatives[i]);
+		for (j = 1; j < n_alt[i]; ++j)
+			ppmu->get_constraint(cpuhw->alternatives[i][j],
+					     &cpuhw->amasks[i][j],
+					     &cpuhw->avalues[i][j]);
+	}
+
+	/* enumerate all possibilities and see if any will work */
+	i = 0;
+	j = -1;
+	value = mask = nv = 0;
+	while (i < n_ev) {
+		if (j >= 0) {
+			/* we're backtracking, restore context */
+			value = svalues[i];
+			mask = smasks[i];
+			j = choice[i];
+		}
+		/*
+		 * See if any alternative k for event_id i,
+		 * where k > j, will satisfy the constraints.
+		 */
+		while (++j < n_alt[i]) {
+			nv = (value | cpuhw->avalues[i][j]) +
+				(value & cpuhw->avalues[i][j] & addf);
+			if ((((nv + tadd) ^ value) & mask) == 0 &&
+			    (((nv + tadd) ^ cpuhw->avalues[i][j])
+			     & cpuhw->amasks[i][j]) == 0)
+				break;
+		}
+		if (j >= n_alt[i]) {
+			/*
+			 * No feasible alternative, backtrack
+			 * to event_id i-1 and continue enumerating its
+			 * alternatives from where we got up to.
+			 */
+			if (--i < 0)
+				return -1;
+		} else {
+			/*
+			 * Found a feasible alternative for event_id i,
+			 * remember where we got up to with this event_id,
+			 * go on to the next event_id, and start with
+			 * the first alternative for it.
+			 */
+			choice[i] = j;
+			svalues[i] = value;
+			smasks[i] = mask;
+			value = nv;
+			mask |= cpuhw->amasks[i][j];
+			++i;
+			j = -1;
+		}
+	}
+
+	/* OK, we have a feasible combination, tell the caller the solution */
+	for (i = 0; i < n_ev; ++i)
+		event_id[i] = cpuhw->alternatives[i][choice[i]];
+	return 0;
+}
+
+/*
+ * Check if newly-added events have consistent settings for
+ * exclude_{user,kernel,hv} with each other and any previously
+ * added events.
+ */
+static int check_excludes(struct perf_event **ctrs, unsigned int cflags[],
+			  int n_prev, int n_new)
+{
+	int eu = 0, ek = 0, eh = 0;
+	int i, n, first;
+	struct perf_event *event;
+
+	n = n_prev + n_new;
+	if (n <= 1)
+		return 0;
+
+	first = 1;
+	for (i = 0; i < n; ++i) {
+		if (cflags[i] & PPMU_LIMITED_PMC_OK) {
+			cflags[i] &= ~PPMU_LIMITED_PMC_REQD;
+			continue;
+		}
+		event = ctrs[i];
+		if (first) {
+			eu = event->attr.exclude_user;
+			ek = event->attr.exclude_kernel;
+			eh = event->attr.exclude_hv;
+			first = 0;
+		} else if (event->attr.exclude_user != eu ||
+			   event->attr.exclude_kernel != ek ||
+			   event->attr.exclude_hv != eh) {
+			return -EAGAIN;
+		}
+	}
+
+	if (eu || ek || eh)
+		for (i = 0; i < n; ++i)
+			if (cflags[i] & PPMU_LIMITED_PMC_OK)
+				cflags[i] |= PPMU_LIMITED_PMC_REQD;
+
+	return 0;
+}
+
+static void power_pmu_read(struct perf_event *event)
+{
+	s64 val, delta, prev;
+
+	if (!event->hw.idx)
+		return;
+	/*
+	 * Performance monitor interrupts come even when interrupts
+	 * are soft-disabled, as long as interrupts are hard-enabled.
+	 * Therefore we treat them like NMIs.
+	 */
+	do {
+		prev = atomic64_read(&event->hw.prev_count);
+		barrier();
+		val = read_pmc(event->hw.idx);
+	} while (atomic64_cmpxchg(&event->hw.prev_count, prev, val) != prev);
+
+	/* The counters are only 32 bits wide */
+	delta = (val - prev) & 0xfffffffful;
+	atomic64_add(delta, &event->count);
+	atomic64_sub(delta, &event->hw.period_left);
+}
+
+/*
+ * On some machines, PMC5 and PMC6 can't be written, don't respect
+ * the freeze conditions, and don't generate interrupts.  This tells
+ * us if `event' is using such a PMC.
+ */
+static int is_limited_pmc(int pmcnum)
+{
+	return (ppmu->flags & PPMU_LIMITED_PMC5_6)
+		&& (pmcnum == 5 || pmcnum == 6);
+}
+
+static void freeze_limited_counters(struct cpu_hw_events *cpuhw,
+				    unsigned long pmc5, unsigned long pmc6)
+{
+	struct perf_event *event;
+	u64 val, prev, delta;
+	int i;
+
+	for (i = 0; i < cpuhw->n_limited; ++i) {
+		event = cpuhw->limited_counter[i];
+		if (!event->hw.idx)
+			continue;
+		val = (event->hw.idx == 5) ? pmc5 : pmc6;
+		prev = atomic64_read(&event->hw.prev_count);
+		event->hw.idx = 0;
+		delta = (val - prev) & 0xfffffffful;
+		atomic64_add(delta, &event->count);
+	}
+}
+
+static void thaw_limited_counters(struct cpu_hw_events *cpuhw,
+				  unsigned long pmc5, unsigned long pmc6)
+{
+	struct perf_event *event;
+	u64 val;
+	int i;
+
+	for (i = 0; i < cpuhw->n_limited; ++i) {
+		event = cpuhw->limited_counter[i];
+		event->hw.idx = cpuhw->limited_hwidx[i];
+		val = (event->hw.idx == 5) ? pmc5 : pmc6;
+		atomic64_set(&event->hw.prev_count, val);
+		perf_event_update_userpage(event);
+	}
+}
+
+/*
+ * Since limited events don't respect the freeze conditions, we
+ * have to read them immediately after freezing or unfreezing the
+ * other events.  We try to keep the values from the limited
+ * events as consistent as possible by keeping the delay (in
+ * cycles and instructions) between freezing/unfreezing and reading
+ * the limited events as small and consistent as possible.
+ * Therefore, if any limited events are in use, we read them
+ * both, and always in the same order, to minimize variability,
+ * and do it inside the same asm that writes MMCR0.
+ */
+static void write_mmcr0(struct cpu_hw_events *cpuhw, unsigned long mmcr0)
+{
+	unsigned long pmc5, pmc6;
+
+	if (!cpuhw->n_limited) {
+		mtspr(SPRN_MMCR0, mmcr0);
+		return;
+	}
+
+	/*
+	 * Write MMCR0, then read PMC5 and PMC6 immediately.
+	 * To ensure we don't get a performance monitor interrupt
+	 * between writing MMCR0 and freezing/thawing the limited
+	 * events, we first write MMCR0 with the event overflow
+	 * interrupt enable bits turned off.
+	 */
+	asm volatile("mtspr %3,%2; mfspr %0,%4; mfspr %1,%5"
+		     : "=&r" (pmc5), "=&r" (pmc6)
+		     : "r" (mmcr0 & ~(MMCR0_PMC1CE | MMCR0_PMCjCE)),
+		       "i" (SPRN_MMCR0),
+		       "i" (SPRN_PMC5), "i" (SPRN_PMC6));
+
+	if (mmcr0 & MMCR0_FC)
+		freeze_limited_counters(cpuhw, pmc5, pmc6);
+	else
+		thaw_limited_counters(cpuhw, pmc5, pmc6);
+
+	/*
+	 * Write the full MMCR0 including the event overflow interrupt
+	 * enable bits, if necessary.
+	 */
+	if (mmcr0 & (MMCR0_PMC1CE | MMCR0_PMCjCE))
+		mtspr(SPRN_MMCR0, mmcr0);
+}
+
+/*
+ * Disable all events to prevent PMU interrupts and to allow
+ * events to be added or removed.
+ */
+void hw_perf_disable(void)
+{
+	struct cpu_hw_events *cpuhw;
+	unsigned long flags;
+
+	if (!ppmu)
+		return;
+	local_irq_save(flags);
+	cpuhw = &__get_cpu_var(cpu_hw_events);
+
+	if (!cpuhw->disabled) {
+		cpuhw->disabled = 1;
+		cpuhw->n_added = 0;
+
+		/*
+		 * Check if we ever enabled the PMU on this cpu.
+		 */
+		if (!cpuhw->pmcs_enabled) {
+			ppc_enable_pmcs();
+			cpuhw->pmcs_enabled = 1;
+		}
+
+		/*
+		 * Disable instruction sampling if it was enabled
+		 */
+		if (cpuhw->mmcr[2] & MMCRA_SAMPLE_ENABLE) {
+			mtspr(SPRN_MMCRA,
+			      cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE);
+			mb();
+		}
+
+		/*
+		 * Set the 'freeze counters' bit.
+		 * The barrier is to make sure the mtspr has been
+		 * executed and the PMU has frozen the events
+		 * before we return.
+		 */
+		write_mmcr0(cpuhw, mfspr(SPRN_MMCR0) | MMCR0_FC);
+		mb();
+	}
+	local_irq_restore(flags);
+}
+
+/*
+ * Re-enable all events if disable == 0.
+ * If we were previously disabled and events were added, then
+ * put the new config on the PMU.
+ */
+void hw_perf_enable(void)
+{
+	struct perf_event *event;
+	struct cpu_hw_events *cpuhw;
+	unsigned long flags;
+	long i;
+	unsigned long val;
+	s64 left;
+	unsigned int hwc_index[MAX_HWEVENTS];
+	int n_lim;
+	int idx;
+
+	if (!ppmu)
+		return;
+	local_irq_save(flags);
+	cpuhw = &__get_cpu_var(cpu_hw_events);
+	if (!cpuhw->disabled) {
+		local_irq_restore(flags);
+		return;
+	}
+	cpuhw->disabled = 0;
+
+	/*
+	 * If we didn't change anything, or only removed events,
+	 * no need to recalculate MMCR* settings and reset the PMCs.
+	 * Just reenable the PMU with the current MMCR* settings
+	 * (possibly updated for removal of events).
+	 */
+	if (!cpuhw->n_added) {
+		mtspr(SPRN_MMCRA, cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE);
+		mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
+		if (cpuhw->n_events == 0)
+			ppc_set_pmu_inuse(0);
+		goto out_enable;
+	}
+
+	/*
+	 * Compute MMCR* values for the new set of events
+	 */
+	if (ppmu->compute_mmcr(cpuhw->events, cpuhw->n_events, hwc_index,
+			       cpuhw->mmcr)) {
+		/* shouldn't ever get here */
+		printk(KERN_ERR "oops compute_mmcr failed\n");
+		goto out;
+	}
+
+	/*
+	 * Add in MMCR0 freeze bits corresponding to the
+	 * attr.exclude_* bits for the first event.
+	 * We have already checked that all events have the
+	 * same values for these bits as the first event.
+	 */
+	event = cpuhw->event[0];
+	if (event->attr.exclude_user)
+		cpuhw->mmcr[0] |= MMCR0_FCP;
+	if (event->attr.exclude_kernel)
+		cpuhw->mmcr[0] |= freeze_events_kernel;
+	if (event->attr.exclude_hv)
+		cpuhw->mmcr[0] |= MMCR0_FCHV;
+
+	/*
+	 * Write the new configuration to MMCR* with the freeze
+	 * bit set and set the hardware events to their initial values.
+	 * Then unfreeze the events.
+	 */
+	ppc_set_pmu_inuse(1);
+	mtspr(SPRN_MMCRA, cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE);
+	mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
+	mtspr(SPRN_MMCR0, (cpuhw->mmcr[0] & ~(MMCR0_PMC1CE | MMCR0_PMCjCE))
+				| MMCR0_FC);
+
+	/*
+	 * Read off any pre-existing events that need to move
+	 * to another PMC.
+	 */
+	for (i = 0; i < cpuhw->n_events; ++i) {
+		event = cpuhw->event[i];
+		if (event->hw.idx && event->hw.idx != hwc_index[i] + 1) {
+			power_pmu_read(event);
+			write_pmc(event->hw.idx, 0);
+			event->hw.idx = 0;
+		}
+	}
+
+	/*
+	 * Initialize the PMCs for all the new and moved events.
+	 */
+	cpuhw->n_limited = n_lim = 0;
+	for (i = 0; i < cpuhw->n_events; ++i) {
+		event = cpuhw->event[i];
+		if (event->hw.idx)
+			continue;
+		idx = hwc_index[i] + 1;
+		if (is_limited_pmc(idx)) {
+			cpuhw->limited_counter[n_lim] = event;
+			cpuhw->limited_hwidx[n_lim] = idx;
+			++n_lim;
+			continue;
+		}
+		val = 0;
+		if (event->hw.sample_period) {
+			left = atomic64_read(&event->hw.period_left);
+			if (left < 0x80000000L)
+				val = 0x80000000L - left;
+		}
+		atomic64_set(&event->hw.prev_count, val);
+		event->hw.idx = idx;
+		write_pmc(idx, val);
+		perf_event_update_userpage(event);
+	}
+	cpuhw->n_limited = n_lim;
+	cpuhw->mmcr[0] |= MMCR0_PMXE | MMCR0_FCECE;
+
+ out_enable:
+	mb();
+	write_mmcr0(cpuhw, cpuhw->mmcr[0]);
+
+	/*
+	 * Enable instruction sampling if necessary
+	 */
+	if (cpuhw->mmcr[2] & MMCRA_SAMPLE_ENABLE) {
+		mb();
+		mtspr(SPRN_MMCRA, cpuhw->mmcr[2]);
+	}
+
+ out:
+	local_irq_restore(flags);
+}
+
+static int collect_events(struct perf_event *group, int max_count,
+			  struct perf_event *ctrs[], u64 *events,
+			  unsigned int *flags)
+{
+	int n = 0;
+	struct perf_event *event;
+
+	if (!is_software_event(group)) {
+		if (n >= max_count)
+			return -1;
+		ctrs[n] = group;
+		flags[n] = group->hw.event_base;
+		events[n++] = group->hw.config;
+	}
+	list_for_each_entry(event, &group->sibling_list, group_entry) {
+		if (!is_software_event(event) &&
+		    event->state != PERF_EVENT_STATE_OFF) {
+			if (n >= max_count)
+				return -1;
+			ctrs[n] = event;
+			flags[n] = event->hw.event_base;
+			events[n++] = event->hw.config;
+		}
+	}
+	return n;
+}
+
+static void event_sched_in(struct perf_event *event, int cpu)
+{
+	event->state = PERF_EVENT_STATE_ACTIVE;
+	event->oncpu = cpu;
+	event->tstamp_running += event->ctx->time - event->tstamp_stopped;
+	if (is_software_event(event))
+		event->pmu->enable(event);
+}
+
+/*
+ * Called to enable a whole group of events.
+ * Returns 1 if the group was enabled, or -EAGAIN if it could not be.
+ * Assumes the caller has disabled interrupts and has
+ * frozen the PMU with hw_perf_save_disable.
+ */
+int hw_perf_group_sched_in(struct perf_event *group_leader,
+	       struct perf_cpu_context *cpuctx,
+	       struct perf_event_context *ctx, int cpu)
+{
+	struct cpu_hw_events *cpuhw;
+	long i, n, n0;
+	struct perf_event *sub;
+
+	if (!ppmu)
+		return 0;
+	cpuhw = &__get_cpu_var(cpu_hw_events);
+	n0 = cpuhw->n_events;
+	n = collect_events(group_leader, ppmu->n_counter - n0,
+			   &cpuhw->event[n0], &cpuhw->events[n0],
+			   &cpuhw->flags[n0]);
+	if (n < 0)
+		return -EAGAIN;
+	if (check_excludes(cpuhw->event, cpuhw->flags, n0, n))
+		return -EAGAIN;
+	i = power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n + n0);
+	if (i < 0)
+		return -EAGAIN;
+	cpuhw->n_events = n0 + n;
+	cpuhw->n_added += n;
+
+	/*
+	 * OK, this group can go on; update event states etc.,
+	 * and enable any software events
+	 */
+	for (i = n0; i < n0 + n; ++i)
+		cpuhw->event[i]->hw.config = cpuhw->events[i];
+	cpuctx->active_oncpu += n;
+	n = 1;
+	event_sched_in(group_leader, cpu);
+	list_for_each_entry(sub, &group_leader->sibling_list, group_entry) {
+		if (sub->state != PERF_EVENT_STATE_OFF) {
+			event_sched_in(sub, cpu);
+			++n;
+		}
+	}
+	ctx->nr_active += n;
+
+	return 1;
+}
+
+/*
+ * Add a event to the PMU.
+ * If all events are not already frozen, then we disable and
+ * re-enable the PMU in order to get hw_perf_enable to do the
+ * actual work of reconfiguring the PMU.
+ */
+static int power_pmu_enable(struct perf_event *event)
+{
+	struct cpu_hw_events *cpuhw;
+	unsigned long flags;
+	int n0;
+	int ret = -EAGAIN;
+
+	local_irq_save(flags);
+	perf_disable();
+
+	/*
+	 * Add the event to the list (if there is room)
+	 * and check whether the total set is still feasible.
+	 */
+	cpuhw = &__get_cpu_var(cpu_hw_events);
+	n0 = cpuhw->n_events;
+	if (n0 >= ppmu->n_counter)
+		goto out;
+	cpuhw->event[n0] = event;
+	cpuhw->events[n0] = event->hw.config;
+	cpuhw->flags[n0] = event->hw.event_base;
+	if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
+		goto out;
+	if (power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n0 + 1))
+		goto out;
+
+	event->hw.config = cpuhw->events[n0];
+	++cpuhw->n_events;
+	++cpuhw->n_added;
+
+	ret = 0;
+ out:
+	perf_enable();
+	local_irq_restore(flags);
+	return ret;
+}
+
+/*
+ * Remove a event from the PMU.
+ */
+static void power_pmu_disable(struct perf_event *event)
+{
+	struct cpu_hw_events *cpuhw;
+	long i;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	perf_disable();
+
+	power_pmu_read(event);
+
+	cpuhw = &__get_cpu_var(cpu_hw_events);
+	for (i = 0; i < cpuhw->n_events; ++i) {
+		if (event == cpuhw->event[i]) {
+			while (++i < cpuhw->n_events)
+				cpuhw->event[i-1] = cpuhw->event[i];
+			--cpuhw->n_events;
+			ppmu->disable_pmc(event->hw.idx - 1, cpuhw->mmcr);
+			if (event->hw.idx) {
+				write_pmc(event->hw.idx, 0);
+				event->hw.idx = 0;
+			}
+			perf_event_update_userpage(event);
+			break;
+		}
+	}
+	for (i = 0; i < cpuhw->n_limited; ++i)
+		if (event == cpuhw->limited_counter[i])
+			break;
+	if (i < cpuhw->n_limited) {
+		while (++i < cpuhw->n_limited) {
+			cpuhw->limited_counter[i-1] = cpuhw->limited_counter[i];
+			cpuhw->limited_hwidx[i-1] = cpuhw->limited_hwidx[i];
+		}
+		--cpuhw->n_limited;
+	}
+	if (cpuhw->n_events == 0) {
+		/* disable exceptions if no events are running */
+		cpuhw->mmcr[0] &= ~(MMCR0_PMXE | MMCR0_FCECE);
+	}
+
+	perf_enable();
+	local_irq_restore(flags);
+}
+
+/*
+ * Re-enable interrupts on a event after they were throttled
+ * because they were coming too fast.
+ */
+static void power_pmu_unthrottle(struct perf_event *event)
+{
+	s64 val, left;
+	unsigned long flags;
+
+	if (!event->hw.idx || !event->hw.sample_period)
+		return;
+	local_irq_save(flags);
+	perf_disable();
+	power_pmu_read(event);
+	left = event->hw.sample_period;
+	event->hw.last_period = left;
+	val = 0;
+	if (left < 0x80000000L)
+		val = 0x80000000L - left;
+	write_pmc(event->hw.idx, val);
+	atomic64_set(&event->hw.prev_count, val);
+	atomic64_set(&event->hw.period_left, left);
+	perf_event_update_userpage(event);
+	perf_enable();
+	local_irq_restore(flags);
+}
+
+struct pmu power_pmu = {
+	.enable		= power_pmu_enable,
+	.disable	= power_pmu_disable,
+	.read		= power_pmu_read,
+	.unthrottle	= power_pmu_unthrottle,
+};
+
+/*
+ * Return 1 if we might be able to put event on a limited PMC,
+ * or 0 if not.
+ * A event can only go on a limited PMC if it counts something
+ * that a limited PMC can count, doesn't require interrupts, and
+ * doesn't exclude any processor mode.
+ */
+static int can_go_on_limited_pmc(struct perf_event *event, u64 ev,
+				 unsigned int flags)
+{
+	int n;
+	u64 alt[MAX_EVENT_ALTERNATIVES];
+
+	if (event->attr.exclude_user
+	    || event->attr.exclude_kernel
+	    || event->attr.exclude_hv
+	    || event->attr.sample_period)
+		return 0;
+
+	if (ppmu->limited_pmc_event(ev))
+		return 1;
+
+	/*
+	 * The requested event_id isn't on a limited PMC already;
+	 * see if any alternative code goes on a limited PMC.
+	 */
+	if (!ppmu->get_alternatives)
+		return 0;
+
+	flags |= PPMU_LIMITED_PMC_OK | PPMU_LIMITED_PMC_REQD;
+	n = ppmu->get_alternatives(ev, flags, alt);
+
+	return n > 0;
+}
+
+/*
+ * Find an alternative event_id that goes on a normal PMC, if possible,
+ * and return the event_id code, or 0 if there is no such alternative.
+ * (Note: event_id code 0 is "don't count" on all machines.)
+ */
+static u64 normal_pmc_alternative(u64 ev, unsigned long flags)
+{
+	u64 alt[MAX_EVENT_ALTERNATIVES];
+	int n;
+
+	flags &= ~(PPMU_LIMITED_PMC_OK | PPMU_LIMITED_PMC_REQD);
+	n = ppmu->get_alternatives(ev, flags, alt);
+	if (!n)
+		return 0;
+	return alt[0];
+}
+
+/* Number of perf_events counting hardware events */
+static atomic_t num_events;
+/* Used to avoid races in calling reserve/release_pmc_hardware */
+static DEFINE_MUTEX(pmc_reserve_mutex);
+
+/*
+ * Release the PMU if this is the last perf_event.
+ */
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+	if (!atomic_add_unless(&num_events, -1, 1)) {
+		mutex_lock(&pmc_reserve_mutex);
+		if (atomic_dec_return(&num_events) == 0)
+			release_pmc_hardware();
+		mutex_unlock(&pmc_reserve_mutex);
+	}
+}
+
+/*
+ * Translate a generic cache event_id config to a raw event_id code.
+ */
+static int hw_perf_cache_event(u64 config, u64 *eventp)
+{
+	unsigned long type, op, result;
+	int ev;
+
+	if (!ppmu->cache_events)
+		return -EINVAL;
+
+	/* unpack config */
+	type = config & 0xff;
+	op = (config >> 8) & 0xff;
+	result = (config >> 16) & 0xff;
+
+	if (type >= PERF_COUNT_HW_CACHE_MAX ||
+	    op >= PERF_COUNT_HW_CACHE_OP_MAX ||
+	    result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+		return -EINVAL;
+
+	ev = (*ppmu->cache_events)[type][op][result];
+	if (ev == 0)
+		return -EOPNOTSUPP;
+	if (ev == -1)
+		return -EINVAL;
+	*eventp = ev;
+	return 0;
+}
+
+const struct pmu *hw_perf_event_init(struct perf_event *event)
+{
+	u64 ev;
+	unsigned long flags;
+	struct perf_event *ctrs[MAX_HWEVENTS];
+	u64 events[MAX_HWEVENTS];
+	unsigned int cflags[MAX_HWEVENTS];
+	int n;
+	int err;
+	struct cpu_hw_events *cpuhw;
+
+	if (!ppmu)
+		return ERR_PTR(-ENXIO);
+	switch (event->attr.type) {
+	case PERF_TYPE_HARDWARE:
+		ev = event->attr.config;
+		if (ev >= ppmu->n_generic || ppmu->generic_events[ev] == 0)
+			return ERR_PTR(-EOPNOTSUPP);
+		ev = ppmu->generic_events[ev];
+		break;
+	case PERF_TYPE_HW_CACHE:
+		err = hw_perf_cache_event(event->attr.config, &ev);
+		if (err)
+			return ERR_PTR(err);
+		break;
+	case PERF_TYPE_RAW:
+		ev = event->attr.config;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+	event->hw.config_base = ev;
+	event->hw.idx = 0;
+
+	/*
+	 * If we are not running on a hypervisor, force the
+	 * exclude_hv bit to 0 so that we don't care what
+	 * the user set it to.
+	 */
+	if (!firmware_has_feature(FW_FEATURE_LPAR))
+		event->attr.exclude_hv = 0;
+
+	/*
+	 * If this is a per-task event, then we can use
+	 * PM_RUN_* events interchangeably with their non RUN_*
+	 * equivalents, e.g. PM_RUN_CYC instead of PM_CYC.
+	 * XXX we should check if the task is an idle task.
+	 */
+	flags = 0;
+	if (event->ctx->task)
+		flags |= PPMU_ONLY_COUNT_RUN;
+
+	/*
+	 * If this machine has limited events, check whether this
+	 * event_id could go on a limited event.
+	 */
+	if (ppmu->flags & PPMU_LIMITED_PMC5_6) {
+		if (can_go_on_limited_pmc(event, ev, flags)) {
+			flags |= PPMU_LIMITED_PMC_OK;
+		} else if (ppmu->limited_pmc_event(ev)) {
+			/*
+			 * The requested event_id is on a limited PMC,
+			 * but we can't use a limited PMC; see if any
+			 * alternative goes on a normal PMC.
+			 */
+			ev = normal_pmc_alternative(ev, flags);
+			if (!ev)
+				return ERR_PTR(-EINVAL);
+		}
+	}
+
+	/*
+	 * If this is in a group, check if it can go on with all the
+	 * other hardware events in the group.  We assume the event
+	 * hasn't been linked into its leader's sibling list at this point.
+	 */
+	n = 0;
+	if (event->group_leader != event) {
+		n = collect_events(event->group_leader, ppmu->n_counter - 1,
+				   ctrs, events, cflags);
+		if (n < 0)
+			return ERR_PTR(-EINVAL);
+	}
+	events[n] = ev;
+	ctrs[n] = event;
+	cflags[n] = flags;
+	if (check_excludes(ctrs, cflags, n, 1))
+		return ERR_PTR(-EINVAL);
+
+	cpuhw = &get_cpu_var(cpu_hw_events);
+	err = power_check_constraints(cpuhw, events, cflags, n + 1);
+	put_cpu_var(cpu_hw_events);
+	if (err)
+		return ERR_PTR(-EINVAL);
+
+	event->hw.config = events[n];
+	event->hw.event_base = cflags[n];
+	event->hw.last_period = event->hw.sample_period;
+	atomic64_set(&event->hw.period_left, event->hw.last_period);
+
+	/*
+	 * See if we need to reserve the PMU.
+	 * If no events are currently in use, then we have to take a
+	 * mutex to ensure that we don't race with another task doing
+	 * reserve_pmc_hardware or release_pmc_hardware.
+	 */
+	err = 0;
+	if (!atomic_inc_not_zero(&num_events)) {
+		mutex_lock(&pmc_reserve_mutex);
+		if (atomic_read(&num_events) == 0 &&
+		    reserve_pmc_hardware(perf_event_interrupt))
+			err = -EBUSY;
+		else
+			atomic_inc(&num_events);
+		mutex_unlock(&pmc_reserve_mutex);
+	}
+	event->destroy = hw_perf_event_destroy;
+
+	if (err)
+		return ERR_PTR(err);
+	return &power_pmu;
+}
+
+/*
+ * A counter has overflowed; update its count and record
+ * things if requested.  Note that interrupts are hard-disabled
+ * here so there is no possibility of being interrupted.
+ */
+static void record_and_restart(struct perf_event *event, unsigned long val,
+			       struct pt_regs *regs, int nmi)
+{
+	u64 period = event->hw.sample_period;
+	s64 prev, delta, left;
+	int record = 0;
+
+	/* we don't have to worry about interrupts here */
+	prev = atomic64_read(&event->hw.prev_count);
+	delta = (val - prev) & 0xfffffffful;
+	atomic64_add(delta, &event->count);
+
+	/*
+	 * See if the total period for this event has expired,
+	 * and update for the next period.
+	 */
+	val = 0;
+	left = atomic64_read(&event->hw.period_left) - delta;
+	if (period) {
+		if (left <= 0) {
+			left += period;
+			if (left <= 0)
+				left = period;
+			record = 1;
+		}
+		if (left < 0x80000000LL)
+			val = 0x80000000LL - left;
+	}
+
+	/*
+	 * Finally record data if requested.
+	 */
+	if (record) {
+		struct perf_sample_data data = {
+			.addr	= 0,
+			.period	= event->hw.last_period,
+		};
+
+		if (event->attr.sample_type & PERF_SAMPLE_ADDR)
+			perf_get_data_addr(regs, &data.addr);
+
+		if (perf_event_overflow(event, nmi, &data, regs)) {
+			/*
+			 * Interrupts are coming too fast - throttle them
+			 * by setting the event to 0, so it will be
+			 * at least 2^30 cycles until the next interrupt
+			 * (assuming each event counts at most 2 counts
+			 * per cycle).
+			 */
+			val = 0;
+			left = ~0ULL >> 1;
+		}
+	}
+
+	write_pmc(event->hw.idx, val);
+	atomic64_set(&event->hw.prev_count, val);
+	atomic64_set(&event->hw.period_left, left);
+	perf_event_update_userpage(event);
+}
+
+/*
+ * Called from generic code to get the misc flags (i.e. processor mode)
+ * for an event_id.
+ */
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+	u32 flags = perf_get_misc_flags(regs);
+
+	if (flags)
+		return flags;
+	return user_mode(regs) ? PERF_RECORD_MISC_USER :
+		PERF_RECORD_MISC_KERNEL;
+}
+
+/*
+ * Called from generic code to get the instruction pointer
+ * for an event_id.
+ */
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+	unsigned long ip;
+
+	if (TRAP(regs) != 0xf00)
+		return regs->nip;	/* not a PMU interrupt */
+
+	ip = mfspr(SPRN_SIAR) + perf_ip_adjust(regs);
+	return ip;
+}
+
+/*
+ * Performance monitor interrupt stuff
+ */
+static void perf_event_interrupt(struct pt_regs *regs)
+{
+	int i;
+	struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+	struct perf_event *event;
+	unsigned long val;
+	int found = 0;
+	int nmi;
+
+	if (cpuhw->n_limited)
+		freeze_limited_counters(cpuhw, mfspr(SPRN_PMC5),
+					mfspr(SPRN_PMC6));
+
+	perf_read_regs(regs);
+
+	nmi = perf_intr_is_nmi(regs);
+	if (nmi)
+		nmi_enter();
+	else
+		irq_enter();
+
+	for (i = 0; i < cpuhw->n_events; ++i) {
+		event = cpuhw->event[i];
+		if (!event->hw.idx || is_limited_pmc(event->hw.idx))
+			continue;
+		val = read_pmc(event->hw.idx);
+		if ((int)val < 0) {
+			/* event has overflowed */
+			found = 1;
+			record_and_restart(event, val, regs, nmi);
+		}
+	}
+
+	/*
+	 * In case we didn't find and reset the event that caused
+	 * the interrupt, scan all events and reset any that are
+	 * negative, to avoid getting continual interrupts.
+	 * Any that we processed in the previous loop will not be negative.
+	 */
+	if (!found) {
+		for (i = 0; i < ppmu->n_counter; ++i) {
+			if (is_limited_pmc(i + 1))
+				continue;
+			val = read_pmc(i + 1);
+			if ((int)val < 0)
+				write_pmc(i + 1, 0);
+		}
+	}
+
+	/*
+	 * Reset MMCR0 to its normal value.  This will set PMXE and
+	 * clear FC (freeze counters) and PMAO (perf mon alert occurred)
+	 * and thus allow interrupts to occur again.
+	 * XXX might want to use MSR.PM to keep the events frozen until
+	 * we get back out of this interrupt.
+	 */
+	write_mmcr0(cpuhw, cpuhw->mmcr[0]);
+
+	if (nmi)
+		nmi_exit();
+	else
+		irq_exit();
+}
+
+void hw_perf_event_setup(int cpu)
+{
+	struct cpu_hw_events *cpuhw = &per_cpu(cpu_hw_events, cpu);
+
+	if (!ppmu)
+		return;
+	memset(cpuhw, 0, sizeof(*cpuhw));
+	cpuhw->mmcr[0] = MMCR0_FC;
+}
+
+int register_power_pmu(struct power_pmu *pmu)
+{
+	if (ppmu)
+		return -EBUSY;		/* something's already registered */
+
+	ppmu = pmu;
+	pr_info("%s performance monitor hardware support registered\n",
+		pmu->name);
+
+#ifdef MSR_HV
+	/*
+	 * Use FCHV to ignore kernel events if MSR.HV is set.
+	 */
+	if (mfmsr() & MSR_HV)
+		freeze_events_kernel = MMCR0_FCHV;
+#endif /* CONFIG_PPC64 */
+
+	return 0;
+}