perf: Do the big rename: Performance Counters -> Performance Events

Bye-bye Performance Counters, welcome Performance Events!

In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.

Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.

All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)

The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.

Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.

User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)

This patch has been generated via the following script:

  FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

  sed -i \
    -e 's/PERF_EVENT_/PERF_RECORD_/g' \
    -e 's/PERF_COUNTER/PERF_EVENT/g' \
    -e 's/perf_counter/perf_event/g' \
    -e 's/nb_counters/nb_events/g' \
    -e 's/swcounter/swevent/g' \
    -e 's/tpcounter_event/tp_event/g' \
    $FILES

  for N in $(find . -name perf_counter.[ch]); do
    M=$(echo $N | sed 's/perf_counter/perf_event/g')
    mv $N $M
  done

  FILES=$(find . -name perf_event.*)

  sed -i \
    -e 's/COUNTER_MASK/REG_MASK/g' \
    -e 's/COUNTER/EVENT/g' \
    -e 's/\<event\>/event_id/g' \
    -e 's/counter/event/g' \
    -e 's/Counter/Event/g' \
    $FILES

... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.

Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.

( NOTE: 'counters' are still the proper terminology when we deal
  with hardware registers - and these sed scripts are a bit
  over-eager in renaming them. I've undone some of that, but
  in case there's something left where 'counter' would be
  better than 'event' we can undo that on an individual basis
  instead of touching an otherwise nicely automated patch. )

Suggested-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1315 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c
new file mode 100644
index 00000000000..c98321fcb45
--- /dev/null
+++ b/arch/powerpc/kernel/perf_event.c
@@ -0,0 +1,1315 @@
+/*
+ * 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_event[MAX_LIMITED_HWEVENTS];
+        u8  limited_hwidx[MAX_LIMITED_HWEVENTS];
+        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 events
+ * 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;
+
+        if (TRAP(regs) != 0xf00)
+                return 0;       /* not a PMU interrupt */
+
+        if (ppmu->flags & PPMU_ALT_SIPR) {
+                if (mmcra & POWER6_MMCRA_SIHV)
+                        return PERF_RECORD_MISC_HYPERVISOR;
+                return (mmcra & POWER6_MMCRA_SIPR) ?
+                        PERF_RECORD_MISC_USER : PERF_RECORD_MISC_KERNEL;
+        }
+        if (mmcra & MMCRA_SIHV)
+                return PERF_RECORD_MISC_HYPERVISOR;
+        return (mmcra & MMCRA_SIPR) ? PERF_RECORD_MISC_USER :
+                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 event (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_event)
+                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 events 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_events(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_event[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_events(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_event[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_events(cpuhw, pmc5, pmc6);
+        else
+                thaw_limited_events(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 events' 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_event[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, list_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_event - 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, list_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_event)
+                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_event[i])
+                        break;
+        if (i < cpuhw->n_limited) {
+                while (++i < cpuhw->n_limited) {
+                        cpuhw->limited_event[i-1] = cpuhw->limited_event[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_event - 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 event 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_events(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_event; ++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 events) 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;
+}