mm: abstract the vma_merge()/split_vma() pattern for mprotect() et al.

[linux.git] / arch / powerpc / perf / core-book3s.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Performance event support - powerpc architecture code
 *
 * Copyright 2008-2009 Paul Mackerras, IBM Corporation.
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/perf_event.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <asm/reg.h>
#include <asm/pmc.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/ptrace.h>
#include <asm/code-patching.h>
#include <asm/hw_irq.h>
#include <asm/interrupt.h>

#ifdef CONFIG_PPC64
#include "internal.h"
#endif

#define BHRB_MAX_ENTRIES        32
#define BHRB_TARGET             0x0000000000000002
#define BHRB_PREDICTION         0x0000000000000001
#define BHRB_EA                 0xFFFFFFFFFFFFFFFCUL

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];
        struct mmcr_regs mmcr;
        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];

        unsigned int txn_flags;
        int n_txn_start;

        /* BHRB bits */
        u64                             bhrb_filter;    /* BHRB HW branch filter */
        unsigned int                    bhrb_users;
        void                            *bhrb_context;
        struct  perf_branch_stack       bhrb_stack;
        struct  perf_branch_entry       bhrb_entries[BHRB_MAX_ENTRIES];
        u64                             ic_init;

        /* Store the PMC values */
        unsigned long pmcs[MAX_HWEVENTS];
};

static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);

static 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.
 * Also 32-bit doesn't have MMCR3, SIER2 and SIER3.
 * Define them as zero knowing that any code path accessing
 * these registers (via mtspr/mfspr) are done under ppmu flag
 * check for PPMU_ARCH_31 and we will not enter that code path
 * for 32-bit.
 */
#ifdef CONFIG_PPC32

#define MMCR0_FCHV              0
#define MMCR0_PMCjCE            MMCR0_PMCnCE
#define MMCR0_FC56              0
#define MMCR0_PMAO              0
#define MMCR0_EBE               0
#define MMCR0_BHRBA             0
#define MMCR0_PMCC              0
#define MMCR0_PMCC_U6           0

#define SPRN_MMCRA              SPRN_MMCR2
#define SPRN_MMCR3              0
#define SPRN_SIER2              0
#define SPRN_SIER3              0
#define MMCRA_SAMPLE_ENABLE     0
#define MMCRA_BHRB_DISABLE     0
#define MMCR0_PMCCEXT           0

static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
{
        return 0;
}
static inline void perf_get_data_addr(struct perf_event *event, 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)
{
        regs->result = 0;
}

static inline int siar_valid(struct pt_regs *regs)
{
        return 1;
}

static bool is_ebb_event(struct perf_event *event) { return false; }
static int ebb_event_check(struct perf_event *event) { return 0; }
static void ebb_event_add(struct perf_event *event) { }
static void ebb_switch_out(unsigned long mmcr0) { }
static unsigned long ebb_switch_in(bool ebb, struct cpu_hw_events *cpuhw)
{
        return cpuhw->mmcr.mmcr0;
}

static inline void power_pmu_bhrb_enable(struct perf_event *event) {}
static inline void power_pmu_bhrb_disable(struct perf_event *event) {}
static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) {}
static inline void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw) {}
static void pmao_restore_workaround(bool ebb) { }
#endif /* CONFIG_PPC32 */

bool is_sier_available(void)
{
        if (!ppmu)
                return false;

        if (ppmu->flags & PPMU_HAS_SIER)
                return true;

        return false;
}

/*
 * Return PMC value corresponding to the
 * index passed.
 */
unsigned long get_pmcs_ext_regs(int idx)
{
        struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);

        return cpuhw->pmcs[idx];
}

static bool regs_use_siar(struct pt_regs *regs)
{
        /*
         * When we take a performance monitor exception the regs are setup
         * using perf_read_regs() which overloads some fields, in particular
         * regs->result to tell us whether to use SIAR.
         *
         * However if the regs are from another exception, eg. a syscall, then
         * they have not been setup using perf_read_regs() and so regs->result
         * is something random.
         */
        return ((TRAP(regs) == INTERRUPT_PERFMON) && regs->result);
}

/*
 * 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 ((ppmu->flags & PPMU_HAS_SSLOT) && (mmcra & MMCRA_SAMPLE_ENABLE)) {
                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, the
 * [POWER7P_]MMCRA_SDAR_VALID bit in MMCRA, or the SDAR_VALID bit in SIER.
 */
static inline void perf_get_data_addr(struct perf_event *event, struct pt_regs *regs, u64 *addrp)
{
        unsigned long mmcra = regs->dsisr;
        bool sdar_valid;

        if (ppmu->flags & PPMU_HAS_SIER)
                sdar_valid = regs->dar & SIER_SDAR_VALID;
        else {
                unsigned long sdsync;

                if (ppmu->flags & PPMU_SIAR_VALID)
                        sdsync = POWER7P_MMCRA_SDAR_VALID;
                else if (ppmu->flags & PPMU_ALT_SIPR)
                        sdsync = POWER6_MMCRA_SDSYNC;
                else if (ppmu->flags & PPMU_NO_SIAR)
                        sdsync = MMCRA_SAMPLE_ENABLE;
                else
                        sdsync = MMCRA_SDSYNC;

                sdar_valid = mmcra & sdsync;
        }

        if (!(mmcra & MMCRA_SAMPLE_ENABLE) || sdar_valid)
                *addrp = mfspr(SPRN_SDAR);

        if (is_kernel_addr(mfspr(SPRN_SDAR)) && event->attr.exclude_kernel)
                *addrp = 0;
}

static bool regs_sihv(struct pt_regs *regs)
{
        unsigned long sihv = MMCRA_SIHV;

        if (ppmu->flags & PPMU_HAS_SIER)
                return !!(regs->dar & SIER_SIHV);

        if (ppmu->flags & PPMU_ALT_SIPR)
                sihv = POWER6_MMCRA_SIHV;

        return !!(regs->dsisr & sihv);
}

static bool regs_sipr(struct pt_regs *regs)
{
        unsigned long sipr = MMCRA_SIPR;

        if (ppmu->flags & PPMU_HAS_SIER)
                return !!(regs->dar & SIER_SIPR);

        if (ppmu->flags & PPMU_ALT_SIPR)
                sipr = POWER6_MMCRA_SIPR;

        return !!(regs->dsisr & sipr);
}

static inline u32 perf_flags_from_msr(struct pt_regs *regs)
{
        if (regs->msr & MSR_PR)
                return PERF_RECORD_MISC_USER;
        if ((regs->msr & MSR_HV) && freeze_events_kernel != MMCR0_FCHV)
                return PERF_RECORD_MISC_HYPERVISOR;
        return PERF_RECORD_MISC_KERNEL;
}

static inline u32 perf_get_misc_flags(struct pt_regs *regs)
{
        bool use_siar = regs_use_siar(regs);
        unsigned long mmcra = regs->dsisr;
        int marked = mmcra & MMCRA_SAMPLE_ENABLE;

        if (!use_siar)
                return perf_flags_from_msr(regs);

        /*
         * Check the address in SIAR to identify the
         * privilege levels since the SIER[MSR_HV, MSR_PR]
         * bits are not set for marked events in power10
         * DD1.
         */
        if (marked && (ppmu->flags & PPMU_P10_DD1)) {
                unsigned long siar = mfspr(SPRN_SIAR);
                if (siar) {
                        if (is_kernel_addr(siar))
                                return PERF_RECORD_MISC_KERNEL;
                        return PERF_RECORD_MISC_USER;
                } else {
                        if (is_kernel_addr(regs->nip))
                                return PERF_RECORD_MISC_KERNEL;
                        return PERF_RECORD_MISC_USER;
                }
        }

        /*
         * If we don't have flags in MMCRA, rather than using
         * the MSR, we intuit the flags from the address in
         * SIAR which should give slightly more reliable
         * results
         */
        if (ppmu->flags & PPMU_NO_SIPR) {
                unsigned long siar = mfspr(SPRN_SIAR);
                if (is_kernel_addr(siar))
                        return PERF_RECORD_MISC_KERNEL;
                return PERF_RECORD_MISC_USER;
        }

        /* PR has priority over HV, so order below is important */
        if (regs_sipr(regs))
                return PERF_RECORD_MISC_USER;

        if (regs_sihv(regs) && (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.
 * Overload regs->dar to store SIER if we have it.
 * Overload regs->result to specify whether we should use the MSR (result
 * is zero) or the SIAR (result is non zero).
 */
static inline void perf_read_regs(struct pt_regs *regs)
{
        unsigned long mmcra = mfspr(SPRN_MMCRA);
        int marked = mmcra & MMCRA_SAMPLE_ENABLE;
        int use_siar;

        regs->dsisr = mmcra;

        if (ppmu->flags & PPMU_HAS_SIER)
                regs->dar = mfspr(SPRN_SIER);

        /*
         * If this isn't a PMU exception (eg a software event) the SIAR is
         * not valid. Use pt_regs.
         *
         * If it is a marked event use the SIAR.
         *
         * If the PMU doesn't update the SIAR for non marked events use
         * pt_regs.
         *
         * If regs is a kernel interrupt, always use SIAR. Some PMUs have an
         * issue with regs_sipr not being in synch with SIAR in interrupt entry
         * and return sequences, which can result in regs_sipr being true for
         * kernel interrupts and SIAR, which has the effect of causing samples
         * to pile up at mtmsrd MSR[EE] 0->1 or pending irq replay around
         * interrupt entry/exit.
         *
         * If the PMU has HV/PR flags then check to see if they
         * place the exception in userspace. If so, use pt_regs. In
         * continuous sampling mode the SIAR and the PMU exception are
         * not synchronised, so they may be many instructions apart.
         * This can result in confusing backtraces. We still want
         * hypervisor samples as well as samples in the kernel with
         * interrupts off hence the userspace check.
         */
        if (TRAP(regs) != INTERRUPT_PERFMON)
                use_siar = 0;
        else if ((ppmu->flags & PPMU_NO_SIAR))
                use_siar = 0;
        else if (marked)
                use_siar = 1;
        else if ((ppmu->flags & PPMU_NO_CONT_SAMPLING))
                use_siar = 0;
        else if (!user_mode(regs))
                use_siar = 1;
        else if (!(ppmu->flags & PPMU_NO_SIPR) && regs_sipr(regs))
                use_siar = 0;
        else
                use_siar = 1;

        regs->result = use_siar;
}

/*
 * On processors like P7+ that have the SIAR-Valid bit, marked instructions
 * must be sampled only if the SIAR-valid bit is set.
 *
 * For unmarked instructions and for processors that don't have the SIAR-Valid
 * bit, assume that SIAR is valid.
 */
static inline int siar_valid(struct pt_regs *regs)
{
        unsigned long mmcra = regs->dsisr;
        int marked = mmcra & MMCRA_SAMPLE_ENABLE;

        if (marked) {
                /*
                 * SIER[SIAR_VALID] is not set for some
                 * marked events on power10 DD1, so drop
                 * the check for SIER[SIAR_VALID] and return true.
                 */
                if (ppmu->flags & PPMU_P10_DD1)
                        return 0x1;
                else if (ppmu->flags & PPMU_HAS_SIER)
                        return regs->dar & SIER_SIAR_VALID;

                if (ppmu->flags & PPMU_SIAR_VALID)
                        return mmcra & POWER7P_MMCRA_SIAR_VALID;
        }

        return 1;
}


/* Reset all possible BHRB entries */
static void power_pmu_bhrb_reset(void)
{
        asm volatile(PPC_CLRBHRB);
}

static void power_pmu_bhrb_enable(struct perf_event *event)
{
        struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);

        if (!ppmu->bhrb_nr)
                return;

        /* Clear BHRB if we changed task context to avoid data leaks */
        if (event->ctx->task && cpuhw->bhrb_context != event->ctx) {
                power_pmu_bhrb_reset();
                cpuhw->bhrb_context = event->ctx;
        }
        cpuhw->bhrb_users++;
        perf_sched_cb_inc(event->pmu);
}

static void power_pmu_bhrb_disable(struct perf_event *event)
{
        struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);

        if (!ppmu->bhrb_nr)
                return;

        WARN_ON_ONCE(!cpuhw->bhrb_users);
        cpuhw->bhrb_users--;
        perf_sched_cb_dec(event->pmu);

        if (!cpuhw->disabled && !cpuhw->bhrb_users) {
                /* BHRB cannot be turned off when other
                 * events are active on the PMU.
                 */

                /* avoid stale pointer */
                cpuhw->bhrb_context = NULL;
        }
}

/* Called from ctxsw to prevent one process's branch entries to
 * mingle with the other process's entries during context switch.
 */
static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
{
        if (!ppmu->bhrb_nr)
                return;

        if (sched_in)
                power_pmu_bhrb_reset();
}
/* Calculate the to address for a branch */
static __u64 power_pmu_bhrb_to(u64 addr)
{
        unsigned int instr;
        __u64 target;

        if (is_kernel_addr(addr)) {
                if (copy_from_kernel_nofault(&instr, (void *)addr,
                                sizeof(instr)))
                        return 0;

                return branch_target(&instr);
        }

        /* Userspace: need copy instruction here then translate it */
        if (copy_from_user_nofault(&instr, (unsigned int __user *)addr,
                        sizeof(instr)))
                return 0;

        target = branch_target(&instr);
        if ((!target) || (instr & BRANCH_ABSOLUTE))
                return target;

        /* Translate relative branch target from kernel to user address */
        return target - (unsigned long)&instr + addr;
}

/* Processing BHRB entries */
static void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw)
{
        u64 val;
        u64 addr;
        int r_index, u_index, pred;

        r_index = 0;
        u_index = 0;
        while (r_index < ppmu->bhrb_nr) {
                /* Assembly read function */
                val = read_bhrb(r_index++);
                if (!val)
                        /* Terminal marker: End of valid BHRB entries */
                        break;
                else {
                        addr = val & BHRB_EA;
                        pred = val & BHRB_PREDICTION;

                        if (!addr)
                                /* invalid entry */
                                continue;

                        /*
                         * BHRB rolling buffer could very much contain the kernel
                         * addresses at this point. Check the privileges before
                         * exporting it to userspace (avoid exposure of regions
                         * where we could have speculative execution)
                         * Incase of ISA v3.1, BHRB will capture only user-space
                         * addresses, hence include a check before filtering code
                         */
                        if (!(ppmu->flags & PPMU_ARCH_31) &&
                            is_kernel_addr(addr) && event->attr.exclude_kernel)
                                continue;

                        /* Branches are read most recent first (ie. mfbhrb 0 is
                         * the most recent branch).
                         * There are two types of valid entries:
                         * 1) a target entry which is the to address of a
                         *    computed goto like a blr,bctr,btar.  The next
                         *    entry read from the bhrb will be branch
                         *    corresponding to this target (ie. the actual
                         *    blr/bctr/btar instruction).
                         * 2) a from address which is an actual branch.  If a
                         *    target entry proceeds this, then this is the
                         *    matching branch for that target.  If this is not
                         *    following a target entry, then this is a branch
                         *    where the target is given as an immediate field
                         *    in the instruction (ie. an i or b form branch).
                         *    In this case we need to read the instruction from
                         *    memory to determine the target/to address.
                         */

                        if (val & BHRB_TARGET) {
                                /* Target branches use two entries
                                 * (ie. computed gotos/XL form)
                                 */
                                cpuhw->bhrb_entries[u_index].to = addr;
                                cpuhw->bhrb_entries[u_index].mispred = pred;
                                cpuhw->bhrb_entries[u_index].predicted = ~pred;

                                /* Get from address in next entry */
                                val = read_bhrb(r_index++);
                                addr = val & BHRB_EA;
                                if (val & BHRB_TARGET) {
                                        /* Shouldn't have two targets in a
                                           row.. Reset index and try again */
                                        r_index--;
                                        addr = 0;
                                }
                                cpuhw->bhrb_entries[u_index].from = addr;
                        } else {
                                /* Branches to immediate field 
                                   (ie I or B form) */
                                cpuhw->bhrb_entries[u_index].from = addr;
                                cpuhw->bhrb_entries[u_index].to =
                                        power_pmu_bhrb_to(addr);
                                cpuhw->bhrb_entries[u_index].mispred = pred;
                                cpuhw->bhrb_entries[u_index].predicted = ~pred;
                        }
                        u_index++;

                }
        }
        cpuhw->bhrb_stack.nr = u_index;
        cpuhw->bhrb_stack.hw_idx = -1ULL;
        return;
}

static bool is_ebb_event(struct perf_event *event)
{
        /*
         * This could be a per-PMU callback, but we'd rather avoid the cost. We
         * check that the PMU supports EBB, meaning those that don't can still
         * use bit 63 of the event code for something else if they wish.
         */
        return (ppmu->flags & PPMU_ARCH_207S) &&
               ((event->attr.config >> PERF_EVENT_CONFIG_EBB_SHIFT) & 1);
}

static int ebb_event_check(struct perf_event *event)
{
        struct perf_event *leader = event->group_leader;

        /* Event and group leader must agree on EBB */
        if (is_ebb_event(leader) != is_ebb_event(event))
                return -EINVAL;

        if (is_ebb_event(event)) {
                if (!(event->attach_state & PERF_ATTACH_TASK))
                        return -EINVAL;

                if (!leader->attr.pinned || !leader->attr.exclusive)
                        return -EINVAL;

                if (event->attr.freq ||
                    event->attr.inherit ||
                    event->attr.sample_type ||
                    event->attr.sample_period ||
                    event->attr.enable_on_exec)
                        return -EINVAL;
        }

        return 0;
}

static void ebb_event_add(struct perf_event *event)
{
        if (!is_ebb_event(event) || current->thread.used_ebb)
                return;

        /*
         * IFF this is the first time we've added an EBB event, set
         * PMXE in the user MMCR0 so we can detect when it's cleared by
         * userspace. We need this so that we can context switch while
         * userspace is in the EBB handler (where PMXE is 0).
         */
        current->thread.used_ebb = 1;
        current->thread.mmcr0 |= MMCR0_PMXE;
}

static void ebb_switch_out(unsigned long mmcr0)
{
        if (!(mmcr0 & MMCR0_EBE))
                return;

        current->thread.siar  = mfspr(SPRN_SIAR);
        current->thread.sier  = mfspr(SPRN_SIER);
        current->thread.sdar  = mfspr(SPRN_SDAR);
        current->thread.mmcr0 = mmcr0 & MMCR0_USER_MASK;
        current->thread.mmcr2 = mfspr(SPRN_MMCR2) & MMCR2_USER_MASK;
        if (ppmu->flags & PPMU_ARCH_31) {
                current->thread.mmcr3 = mfspr(SPRN_MMCR3);
                current->thread.sier2 = mfspr(SPRN_SIER2);
                current->thread.sier3 = mfspr(SPRN_SIER3);
        }
}

static unsigned long ebb_switch_in(bool ebb, struct cpu_hw_events *cpuhw)
{
        unsigned long mmcr0 = cpuhw->mmcr.mmcr0;

        if (!ebb)
                goto out;

        /* Enable EBB and read/write to all 6 PMCs and BHRB for userspace */
        mmcr0 |= MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC_U6;

        /*
         * Add any bits from the user MMCR0, FC or PMAO. This is compatible
         * with pmao_restore_workaround() because we may add PMAO but we never
         * clear it here.
         */
        mmcr0 |= current->thread.mmcr0;

        /*
         * Be careful not to set PMXE if userspace had it cleared. This is also
         * compatible with pmao_restore_workaround() because it has already
         * cleared PMXE and we leave PMAO alone.
         */
        if (!(current->thread.mmcr0 & MMCR0_PMXE))
                mmcr0 &= ~MMCR0_PMXE;

        mtspr(SPRN_SIAR, current->thread.siar);
        mtspr(SPRN_SIER, current->thread.sier);
        mtspr(SPRN_SDAR, current->thread.sdar);

        /*
         * Merge the kernel & user values of MMCR2. The semantics we implement
         * are that the user MMCR2 can set bits, ie. cause counters to freeze,
         * but not clear bits. If a task wants to be able to clear bits, ie.
         * unfreeze counters, it should not set exclude_xxx in its events and
         * instead manage the MMCR2 entirely by itself.
         */
        mtspr(SPRN_MMCR2, cpuhw->mmcr.mmcr2 | current->thread.mmcr2);

        if (ppmu->flags & PPMU_ARCH_31) {
                mtspr(SPRN_MMCR3, current->thread.mmcr3);
                mtspr(SPRN_SIER2, current->thread.sier2);
                mtspr(SPRN_SIER3, current->thread.sier3);
        }
out:
        return mmcr0;
}

static void pmao_restore_workaround(bool ebb)
{
        unsigned pmcs[6];

        if (!cpu_has_feature(CPU_FTR_PMAO_BUG))
                return;

        /*
         * On POWER8E there is a hardware defect which affects the PMU context
         * switch logic, ie. power_pmu_disable/enable().
         *
         * When a counter overflows PMXE is cleared and FC/PMAO is set in MMCR0
         * by the hardware. Sometime later the actual PMU exception is
         * delivered.
         *
         * If we context switch, or simply disable/enable, the PMU prior to the
         * exception arriving, the exception will be lost when we clear PMAO.
         *
         * When we reenable the PMU, we will write the saved MMCR0 with PMAO
         * set, and this _should_ generate an exception. However because of the
         * defect no exception is generated when we write PMAO, and we get
         * stuck with no counters counting but no exception delivered.
         *
         * The workaround is to detect this case and tweak the hardware to
         * create another pending PMU exception.
         *
         * We do that by setting up PMC6 (cycles) for an imminent overflow and
         * enabling the PMU. That causes a new exception to be generated in the
         * chip, but we don't take it yet because we have interrupts hard
         * disabled. We then write back the PMU state as we want it to be seen
         * by the exception handler. When we reenable interrupts the exception
         * handler will be called and see the correct state.
         *
         * The logic is the same for EBB, except that the exception is gated by
         * us having interrupts hard disabled as well as the fact that we are
         * not in userspace. The exception is finally delivered when we return
         * to userspace.
         */

        /* Only if PMAO is set and PMAO_SYNC is clear */
        if ((current->thread.mmcr0 & (MMCR0_PMAO | MMCR0_PMAO_SYNC)) != MMCR0_PMAO)
                return;

        /* If we're doing EBB, only if BESCR[GE] is set */
        if (ebb && !(current->thread.bescr & BESCR_GE))
                return;

        /*
         * We are already soft-disabled in power_pmu_enable(). We need to hard
         * disable to actually prevent the PMU exception from firing.
         */
        hard_irq_disable();

        /*
         * This is a bit gross, but we know we're on POWER8E and have 6 PMCs.
         * Using read/write_pmc() in a for loop adds 12 function calls and
         * almost doubles our code size.
         */
        pmcs[0] = mfspr(SPRN_PMC1);
        pmcs[1] = mfspr(SPRN_PMC2);
        pmcs[2] = mfspr(SPRN_PMC3);
        pmcs[3] = mfspr(SPRN_PMC4);
        pmcs[4] = mfspr(SPRN_PMC5);
        pmcs[5] = mfspr(SPRN_PMC6);

        /* Ensure all freeze bits are unset */
        mtspr(SPRN_MMCR2, 0);

        /* Set up PMC6 to overflow in one cycle */
        mtspr(SPRN_PMC6, 0x7FFFFFFE);

        /* Enable exceptions and unfreeze PMC6 */
        mtspr(SPRN_MMCR0, MMCR0_PMXE | MMCR0_PMCjCE | MMCR0_PMAO);

        /* Now we need to refreeze and restore the PMCs */
        mtspr(SPRN_MMCR0, MMCR0_FC | MMCR0_PMAO);

        mtspr(SPRN_PMC1, pmcs[0]);
        mtspr(SPRN_PMC2, pmcs[1]);
        mtspr(SPRN_PMC3, pmcs[2]);
        mtspr(SPRN_PMC4, pmcs[3]);
        mtspr(SPRN_PMC5, pmcs[4]);
        mtspr(SPRN_PMC6, pmcs[5]);
}

/*
 * If the perf subsystem wants performance monitor interrupts as soon as
 * possible (e.g., to sample the instruction address and stack chain),
 * this should return true. The IRQ masking code can then enable MSR[EE]
 * in some places (e.g., interrupt handlers) that allows PMI interrupts
 * through to improve accuracy of profiles, at the cost of some performance.
 *
 * The PMU counters can be enabled by other means (e.g., sysfs raw SPR
 * access), but in that case there is no need for prompt PMI handling.
 *
 * This currently returns true if any perf counter is being used. It
 * could possibly return false if only events are being counted rather than
 * samples being taken, but for now this is good enough.
 */
bool power_pmu_wants_prompt_pmi(void)
{
        struct cpu_hw_events *cpuhw;

        /*
         * This could simply test local_paca->pmcregs_in_use if that were not
         * under ifdef KVM.
         */
        if (!ppmu)
                return false;

        cpuhw = this_cpu_ptr(&cpu_hw_events);
        return cpuhw->n_events;
}
#endif /* CONFIG_PPC64 */

static void perf_event_interrupt(struct pt_regs *regs);

/*
 * 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);
        }
}

static int any_pmc_overflown(struct cpu_hw_events *cpuhw)
{
        int i, idx;

        for (i = 0; i < cpuhw->n_events; i++) {
                idx = cpuhw->event[i]->hw.idx;
                if ((idx) && ((int)read_pmc(idx) < 0))
                        return idx;
        }

        return 0;
}

/* Called from sysrq_handle_showregs() */
void perf_event_print_debug(void)
{
        unsigned long sdar, sier, flags;
        u32 pmcs[MAX_HWEVENTS];
        int i;

        if (!ppmu) {
                pr_info("Performance monitor hardware not registered.\n");
                return;
        }

        if (!ppmu->n_counter)
                return;

        local_irq_save(flags);

        pr_info("CPU: %d PMU registers, ppmu = %s n_counters = %d",
                 smp_processor_id(), ppmu->name, ppmu->n_counter);

        for (i = 0; i < ppmu->n_counter; i++)
                pmcs[i] = read_pmc(i + 1);

        for (; i < MAX_HWEVENTS; i++)
                pmcs[i] = 0xdeadbeef;

        pr_info("PMC1:  %08x PMC2: %08x PMC3: %08x PMC4: %08x\n",
                 pmcs[0], pmcs[1], pmcs[2], pmcs[3]);

        if (ppmu->n_counter > 4)
                pr_info("PMC5:  %08x PMC6: %08x PMC7: %08x PMC8: %08x\n",
                         pmcs[4], pmcs[5], pmcs[6], pmcs[7]);

        pr_info("MMCR0: %016lx MMCR1: %016lx MMCRA: %016lx\n",
                mfspr(SPRN_MMCR0), mfspr(SPRN_MMCR1), mfspr(SPRN_MMCRA));

        sdar = sier = 0;
#ifdef CONFIG_PPC64
        sdar = mfspr(SPRN_SDAR);

        if (ppmu->flags & PPMU_HAS_SIER)
                sier = mfspr(SPRN_SIER);

        if (ppmu->flags & PPMU_ARCH_207S) {
                pr_info("MMCR2: %016lx EBBHR: %016lx\n",
                        mfspr(SPRN_MMCR2), mfspr(SPRN_EBBHR));
                pr_info("EBBRR: %016lx BESCR: %016lx\n",
                        mfspr(SPRN_EBBRR), mfspr(SPRN_BESCR));
        }

        if (ppmu->flags & PPMU_ARCH_31) {
                pr_info("MMCR3: %016lx SIER2: %016lx SIER3: %016lx\n",
                        mfspr(SPRN_MMCR3), mfspr(SPRN_SIER2), mfspr(SPRN_SIER3));
        }
#endif
        pr_info("SIAR:  %016lx SDAR:  %016lx SIER:  %016lx\n",
                mfspr(SPRN_SIAR), sdar, sier);

        local_irq_restore(flags);
}

/*
 * 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, struct perf_event **event)
{
        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;
        unsigned long grp_mask = ppmu->group_constraint_mask;
        unsigned long grp_val = ppmu->group_constraint_val;

        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], event[i]->attr.config1))
                        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) & (~grp_mask)) != 0)
                        break;

                if (((((nv + tadd) ^ cpuhw->avalues[i][0]) & cpuhw->amasks[i][0])
                        & (~grp_mask)) != 0)
                        break;

                value = nv;
                mask |= cpuhw->amasks[i][0];
        }
        if (i == n_ev) {
                if ((value & mask & grp_mask) != (mask & grp_val))
                        return -1;
                else
                        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],
                                             event[i]->attr.config1);
        }

        /* 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;

        /*
         * If the PMU we're on supports per event exclude settings then we
         * 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)
                return 0;

        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 u64 check_and_compute_delta(u64 prev, u64 val)
{
        u64 delta = (val - prev) & 0xfffffffful;

        /*
         * POWER7 can roll back counter values, if the new value is smaller
         * than the previous value it will cause the delta and the counter to
         * have bogus values unless we rolled a counter over.  If a counter is
         * rolled back, it will be smaller, but within 256, which is the maximum
         * number of events to rollback at once.  If we detect a rollback
         * return 0.  This can lead to a small lack of precision in the
         * counters.
         */
        if (prev > val && (prev - val) < 256)
                delta = 0;

        return delta;
}

static void power_pmu_read(struct perf_event *event)
{
        s64 val, delta, prev;

        if (event->hw.state & PERF_HES_STOPPED)
                return;

        if (!event->hw.idx)
                return;

        if (is_ebb_event(event)) {
                val = read_pmc(event->hw.idx);
                local64_set(&event->hw.prev_count, val);
                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 = local64_read(&event->hw.prev_count);
                barrier();
                val = read_pmc(event->hw.idx);
                delta = check_and_compute_delta(prev, val);
                if (!delta)
                        return;
        } while (local64_cmpxchg(&event->hw.prev_count, prev, val) != prev);

        local64_add(delta, &event->count);

        /*
         * A number of places program the PMC with (0x80000000 - period_left).
         * We never want period_left to be less than 1 because we will program
         * the PMC with a value >= 0x800000000 and an edge detected PMC will
         * roll around to 0 before taking an exception. We have seen this
         * on POWER8.
         *
         * To fix this, clamp the minimum value of period_left to 1.
         */
        do {
                prev = local64_read(&event->hw.period_left);
                val = prev - delta;
                if (val < 1)
                        val = 1;
        } while (local64_cmpxchg(&event->hw.period_left, prev, val) != prev);
}

/*
 * 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 = local64_read(&event->hw.prev_count);
                event->hw.idx = 0;
                delta = check_and_compute_delta(prev, val);
                if (delta)
                        local64_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, prev;
        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;
                prev = local64_read(&event->hw.prev_count);
                if (check_and_compute_delta(prev, val))
                        local64_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.
 */
static void power_pmu_disable(struct pmu *pmu)
{
        struct cpu_hw_events *cpuhw;
        unsigned long flags, mmcr0, val, mmcra;

        if (!ppmu)
                return;
        local_irq_save(flags);
        cpuhw = this_cpu_ptr(&cpu_hw_events);

        if (!cpuhw->disabled) {
                /*
                 * Check if we ever enabled the PMU on this cpu.
                 */
                if (!cpuhw->pmcs_enabled) {
                        ppc_enable_pmcs();
                        cpuhw->pmcs_enabled = 1;
                }

                /*
                 * Set the 'freeze counters' bit, clear EBE/BHRBA/PMCC/PMAO/FC56
                 * Also clear PMXE to disable PMI's getting triggered in some
                 * corner cases during PMU disable.
                 */
                val  = mmcr0 = mfspr(SPRN_MMCR0);
                val |= MMCR0_FC;
                val &= ~(MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC | MMCR0_PMAO |
                         MMCR0_PMXE | MMCR0_FC56);
                /* Set mmcr0 PMCCEXT for p10 */
                if (ppmu->flags & PPMU_ARCH_31)
                        val |= MMCR0_PMCCEXT;

                /*
                 * The barrier is to make sure the mtspr has been
                 * executed and the PMU has frozen the events etc.
                 * before we return.
                 */
                write_mmcr0(cpuhw, val);
                mb();
                isync();

                /*
                 * Some corner cases could clear the PMU counter overflow
                 * while a masked PMI is pending. One such case is when
                 * a PMI happens during interrupt replay and perf counter
                 * values are cleared by PMU callbacks before replay.
                 *
                 * Disable the interrupt by clearing the paca bit for PMI
                 * since we are disabling the PMU now. Otherwise provide a
                 * warning if there is PMI pending, but no counter is found
                 * overflown.
                 *
                 * Since power_pmu_disable runs under local_irq_save, it
                 * could happen that code hits a PMC overflow without PMI
                 * pending in paca. Hence only clear PMI pending if it was
                 * set.
                 *
                 * If a PMI is pending, then MSR[EE] must be disabled (because
                 * the masked PMI handler disabling EE). So it is safe to
                 * call clear_pmi_irq_pending().
                 */
                if (pmi_irq_pending())
                        clear_pmi_irq_pending();

                val = mmcra = cpuhw->mmcr.mmcra;

                /*
                 * Disable instruction sampling if it was enabled
                 */
                if (cpuhw->mmcr.mmcra & MMCRA_SAMPLE_ENABLE)
                        val &= ~MMCRA_SAMPLE_ENABLE;

                /* Disable BHRB via mmcra (BHRBRD) for p10 */
                if (ppmu->flags & PPMU_ARCH_31)
                        val |= MMCRA_BHRB_DISABLE;

                /*
                 * Write SPRN_MMCRA if mmcra has either disabled
                 * instruction sampling or BHRB.
                 */
                if (val != mmcra) {
                        mtspr(SPRN_MMCRA, mmcra);
                        mb();
                        isync();
                }

                cpuhw->disabled = 1;
                cpuhw->n_added = 0;

                ebb_switch_out(mmcr0);

#ifdef CONFIG_PPC64
                /*
                 * These are readable by userspace, may contain kernel
                 * addresses and are not switched by context switch, so clear
                 * them now to avoid leaking anything to userspace in general
                 * including to another process.
                 */
                if (ppmu->flags & PPMU_ARCH_207S) {
                        mtspr(SPRN_SDAR, 0);
                        mtspr(SPRN_SIAR, 0);
                }
#endif
        }

        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.
 */
static void power_pmu_enable(struct pmu *pmu)
{
        struct perf_event *event;
        struct cpu_hw_events *cpuhw;
        unsigned long flags;
        long i;
        unsigned long val, mmcr0;
        s64 left;
        unsigned int hwc_index[MAX_HWEVENTS];
        int n_lim;
        int idx;
        bool ebb;

        if (!ppmu)
                return;
        local_irq_save(flags);

        cpuhw = this_cpu_ptr(&cpu_hw_events);
        if (!cpuhw->disabled)
                goto out;

        if (cpuhw->n_events == 0) {
                ppc_set_pmu_inuse(0);
                goto out;
        }

        cpuhw->disabled = 0;

        /*
         * EBB requires an exclusive group and all events must have the EBB
         * flag set, or not set, so we can just check a single event. Also we
         * know we have at least one event.
         */
        ebb = is_ebb_event(cpuhw->event[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) {
                /*
                 * If there is any active event with an overflown PMC
                 * value, set back PACA_IRQ_PMI which would have been
                 * cleared in power_pmu_disable().
                 */
                hard_irq_disable();
                if (any_pmc_overflown(cpuhw))
                        set_pmi_irq_pending();

                mtspr(SPRN_MMCRA, cpuhw->mmcr.mmcra & ~MMCRA_SAMPLE_ENABLE);
                mtspr(SPRN_MMCR1, cpuhw->mmcr.mmcr1);
                if (ppmu->flags & PPMU_ARCH_31)
                        mtspr(SPRN_MMCR3, cpuhw->mmcr.mmcr3);
                goto out_enable;
        }

        /*
         * Clear all MMCR settings and recompute them for the new set of events.
         */
        memset(&cpuhw->mmcr, 0, sizeof(cpuhw->mmcr));

        if (ppmu->compute_mmcr(cpuhw->events, cpuhw->n_events, hwc_index,
                               &cpuhw->mmcr, cpuhw->event, ppmu->flags)) {
                /* shouldn't ever get here */
                printk(KERN_ERR "oops compute_mmcr failed\n");
                goto out;
        }

        if (!(ppmu->flags & PPMU_ARCH_207S)) {
                /*
                 * 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 value for these bits as the first event.
                 */
                event = cpuhw->event[0];
                if (event->attr.exclude_user)
                        cpuhw->mmcr.mmcr0 |= MMCR0_FCP;
                if (event->attr.exclude_kernel)
                        cpuhw->mmcr.mmcr0 |= freeze_events_kernel;
                if (event->attr.exclude_hv)
                        cpuhw->mmcr.mmcr0 |= 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.mmcra & ~MMCRA_SAMPLE_ENABLE);
        mtspr(SPRN_MMCR1, cpuhw->mmcr.mmcr1);
        mtspr(SPRN_MMCR0, (cpuhw->mmcr.mmcr0 & ~(MMCR0_PMC1CE | MMCR0_PMCjCE))
                                | MMCR0_FC);
        if (ppmu->flags & PPMU_ARCH_207S)
                mtspr(SPRN_MMCR2, cpuhw->mmcr.mmcr2);

        if (ppmu->flags & PPMU_ARCH_31)
                mtspr(SPRN_MMCR3, cpuhw->mmcr.mmcr3);

        /*
         * 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;
                }

                if (ebb)
                        val = local64_read(&event->hw.prev_count);
                else {
                        val = 0;
                        if (event->hw.sample_period) {
                                left = local64_read(&event->hw.period_left);
                                if (left < 0x80000000L)
                                        val = 0x80000000L - left;
                        }
                        local64_set(&event->hw.prev_count, val);
                }

                event->hw.idx = idx;
                if (event->hw.state & PERF_HES_STOPPED)
                        val = 0;
                write_pmc(idx, val);

                perf_event_update_userpage(event);
        }
        cpuhw->n_limited = n_lim;
        cpuhw->mmcr.mmcr0 |= MMCR0_PMXE | MMCR0_FCECE;

 out_enable:
        pmao_restore_workaround(ebb);

        mmcr0 = ebb_switch_in(ebb, cpuhw);

        mb();
        if (cpuhw->bhrb_users)
                ppmu->config_bhrb(cpuhw->bhrb_filter);

        write_mmcr0(cpuhw, mmcr0);

        /*
         * Enable instruction sampling if necessary
         */
        if (cpuhw->mmcr.mmcra & MMCRA_SAMPLE_ENABLE) {
                mb();
                mtspr(SPRN_MMCRA, cpuhw->mmcr.mmcra);
        }

 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 (group->pmu->task_ctx_nr == perf_hw_context) {
                if (n >= max_count)
                        return -1;
                ctrs[n] = group;
                flags[n] = group->hw.event_base;
                events[n++] = group->hw.config;
        }
        for_each_sibling_event(event, group) {
                if (event->pmu->task_ctx_nr == perf_hw_context &&
                    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;
}

/*
 * Add an 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_add(struct perf_event *event, int ef_flags)
{
        struct cpu_hw_events *cpuhw;
        unsigned long flags;
        int n0;
        int ret = -EAGAIN;

        local_irq_save(flags);
        perf_pmu_disable(event->pmu);

        /*
         * Add the event to the list (if there is room)
         * and check whether the total set is still feasible.
         */
        cpuhw = this_cpu_ptr(&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;

        /*
         * This event may have been disabled/stopped in record_and_restart()
         * because we exceeded the ->event_limit. If re-starting the event,
         * clear the ->hw.state (STOPPED and UPTODATE flags), so the user
         * notification is re-enabled.
         */
        if (!(ef_flags & PERF_EF_START))
                event->hw.state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
        else
                event->hw.state = 0;

        /*
         * If group events scheduling transaction was started,
         * skip the schedulability test here, it will be performed
         * at commit time(->commit_txn) as a whole
         */
        if (cpuhw->txn_flags & PERF_PMU_TXN_ADD)
                goto nocheck;

        if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
                goto out;
        if (power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n0 + 1, cpuhw->event))
                goto out;
        event->hw.config = cpuhw->events[n0];

nocheck:
        ebb_event_add(event);

        ++cpuhw->n_events;
        ++cpuhw->n_added;

        ret = 0;
 out:
        if (has_branch_stack(event)) {
                u64 bhrb_filter = -1;

                if (ppmu->bhrb_filter_map)
                        bhrb_filter = ppmu->bhrb_filter_map(
                                event->attr.branch_sample_type);

                if (bhrb_filter != -1) {
                        cpuhw->bhrb_filter = bhrb_filter;
                        power_pmu_bhrb_enable(event);
                }
        }

        perf_pmu_enable(event->pmu);
        local_irq_restore(flags);
        return ret;
}

/*
 * Remove an event from the PMU.
 */
static void power_pmu_del(struct perf_event *event, int ef_flags)
{
        struct cpu_hw_events *cpuhw;
        long i;
        unsigned long flags;

        local_irq_save(flags);
        perf_pmu_disable(event->pmu);

        power_pmu_read(event);

        cpuhw = this_cpu_ptr(&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->events[i-1] = cpuhw->events[i];
                                cpuhw->flags[i-1] = cpuhw->flags[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.mmcr0 &= ~(MMCR0_PMXE | MMCR0_FCECE);
        }

        if (has_branch_stack(event))
                power_pmu_bhrb_disable(event);

        perf_pmu_enable(event->pmu);
        local_irq_restore(flags);
}

/*
 * POWER-PMU does not support disabling individual counters, hence
 * program their cycle counter to their max value and ignore the interrupts.
 */

static void power_pmu_start(struct perf_event *event, int ef_flags)
{
        unsigned long flags;
        s64 left;
        unsigned long val;

        if (!event->hw.idx || !event->hw.sample_period)
                return;

        if (!(event->hw.state & PERF_HES_STOPPED))
                return;

        if (ef_flags & PERF_EF_RELOAD)
                WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));

        local_irq_save(flags);
        perf_pmu_disable(event->pmu);

        event->hw.state = 0;
        left = local64_read(&event->hw.period_left);

        val = 0;
        if (left < 0x80000000L)
                val = 0x80000000L - left;

        write_pmc(event->hw.idx, val);

        perf_event_update_userpage(event);
        perf_pmu_enable(event->pmu);
        local_irq_restore(flags);
}

static void power_pmu_stop(struct perf_event *event, int ef_flags)
{
        unsigned long flags;

        if (!event->hw.idx || !event->hw.sample_period)
                return;

        if (event->hw.state & PERF_HES_STOPPED)
                return;

        local_irq_save(flags);
        perf_pmu_disable(event->pmu);

        power_pmu_read(event);
        event->hw.state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
        write_pmc(event->hw.idx, 0);

        perf_event_update_userpage(event);
        perf_pmu_enable(event->pmu);
        local_irq_restore(flags);
}

/*
 * Start group events scheduling transaction
 * Set the flag to make pmu::enable() not perform the
 * schedulability test, it will be performed at commit time
 *
 * We only support PERF_PMU_TXN_ADD transactions. Save the
 * transaction flags but otherwise ignore non-PERF_PMU_TXN_ADD
 * transactions.
 */
static void power_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
{
        struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);

        WARN_ON_ONCE(cpuhw->txn_flags);         /* txn already in flight */

        cpuhw->txn_flags = txn_flags;
        if (txn_flags & ~PERF_PMU_TXN_ADD)
                return;

        perf_pmu_disable(pmu);
        cpuhw->n_txn_start = cpuhw->n_events;
}

/*
 * Stop group events scheduling transaction
 * Clear the flag and pmu::enable() will perform the
 * schedulability test.
 */
static void power_pmu_cancel_txn(struct pmu *pmu)
{
        struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);
        unsigned int txn_flags;

        WARN_ON_ONCE(!cpuhw->txn_flags);        /* no txn in flight */

        txn_flags = cpuhw->txn_flags;
        cpuhw->txn_flags = 0;
        if (txn_flags & ~PERF_PMU_TXN_ADD)
                return;

        perf_pmu_enable(pmu);
}

/*
 * Commit group events scheduling transaction
 * Perform the group schedulability test as a whole
 * Return 0 if success
 */
static int power_pmu_commit_txn(struct pmu *pmu)
{
        struct cpu_hw_events *cpuhw;
        long i, n;

        if (!ppmu)
                return -EAGAIN;

        cpuhw = this_cpu_ptr(&cpu_hw_events);
        WARN_ON_ONCE(!cpuhw->txn_flags);        /* no txn in flight */

        if (cpuhw->txn_flags & ~PERF_PMU_TXN_ADD) {
                cpuhw->txn_flags = 0;
                return 0;
        }

        n = cpuhw->n_events;
        if (check_excludes(cpuhw->event, cpuhw->flags, 0, n))
                return -EAGAIN;
        i = power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n, cpuhw->event);
        if (i < 0)
                return -EAGAIN;

        for (i = cpuhw->n_txn_start; i < n; ++i)
                cpuhw->event[i]->hw.config = cpuhw->events[i];

        cpuhw->txn_flags = 0;
        perf_pmu_enable(pmu);
        return 0;
}

/*
 * Return 1 if we might be able to put event on a limited PMC,
 * or 0 if not.
 * An 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;
        u64 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;
}

static bool is_event_blacklisted(u64 ev)
{
        int i;

        for (i=0; i < ppmu->n_blacklist_ev; i++) {
                if (ppmu->blacklist_ev[i] == ev)
                        return true;
        }

        return false;
}

static int power_pmu_event_init(struct perf_event *event)
{
        u64 ev;
        unsigned long flags, irq_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 -ENOENT;

        if (has_branch_stack(event)) {
                /* PMU has BHRB enabled */
                if (!(ppmu->flags & PPMU_ARCH_207S))
                        return -EOPNOTSUPP;
        }

        switch (event->attr.type) {
        case PERF_TYPE_HARDWARE:
                ev = event->attr.config;
                if (ev >= ppmu->n_generic || ppmu->generic_events[ev] == 0)
                        return -EOPNOTSUPP;

                if (ppmu->blacklist_ev && is_event_blacklisted(ev))
                        return -EINVAL;
                ev = ppmu->generic_events[ev];
                break;
        case PERF_TYPE_HW_CACHE:
                err = hw_perf_cache_event(event->attr.config, &ev);
                if (err)
                        return err;

                if (ppmu->blacklist_ev && is_event_blacklisted(ev))
                        return -EINVAL;
                break;
        case PERF_TYPE_RAW:
                ev = event->attr.config;

                if (ppmu->blacklist_ev && is_event_blacklisted(ev))
                        return -EINVAL;
                break;
        default:
                return -ENOENT;
        }

        /*
         * PMU config registers have fields that are
         * reserved and some specific values for bit fields are reserved.
         * For ex., MMCRA[61:62] is Random Sampling Mode (SM)
         * and value of 0b11 to this field is reserved.
         * Check for invalid values in attr.config.
         */
        if (ppmu->check_attr_config &&
            ppmu->check_attr_config(event))
                return -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->attach_state & PERF_ATTACH_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 -EINVAL;
                }
        }

        /* Extra checks for EBB */
        err = ebb_event_check(event);
        if (err)
                return err;

        /*
         * 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 -EINVAL;
        }
        events[n] = ev;
        ctrs[n] = event;
        cflags[n] = flags;
        if (check_excludes(ctrs, cflags, n, 1))
                return -EINVAL;

        local_irq_save(irq_flags);
        cpuhw = this_cpu_ptr(&cpu_hw_events);

        err = power_check_constraints(cpuhw, events, cflags, n + 1, ctrs);

        if (has_branch_stack(event)) {
                u64 bhrb_filter = -1;

                /*
                 * Currently no PMU supports having multiple branch filters
                 * at the same time. Branch filters are set via MMCRA IFM[32:33]
                 * bits for Power8 and above. Return EOPNOTSUPP when multiple
                 * branch filters are requested in the event attr.
                 *
                 * When opening event via perf_event_open(), branch_sample_type
                 * gets adjusted in perf_copy_attr(). Kernel will automatically
                 * adjust the branch_sample_type based on the event modifier
                 * settings to include PERF_SAMPLE_BRANCH_PLM_ALL. Hence drop
                 * the check for PERF_SAMPLE_BRANCH_PLM_ALL.
                 */
                if (hweight64(event->attr.branch_sample_type & ~PERF_SAMPLE_BRANCH_PLM_ALL) > 1) {
                        local_irq_restore(irq_flags);
                        return -EOPNOTSUPP;
                }

                if (ppmu->bhrb_filter_map)
                        bhrb_filter = ppmu->bhrb_filter_map(
                                        event->attr.branch_sample_type);

                if (bhrb_filter == -1) {
                        local_irq_restore(irq_flags);
                        return -EOPNOTSUPP;
                }
                cpuhw->bhrb_filter = bhrb_filter;
        }

        local_irq_restore(irq_flags);
        if (err)
                return -EINVAL;

        event->hw.config = events[n];
        event->hw.event_base = cflags[n];
        event->hw.last_period = event->hw.sample_period;
        local64_set(&event->hw.period_left, event->hw.last_period);

        /*
         * For EBB events we just context switch the PMC value, we don't do any
         * of the sample_period logic. We use hw.prev_count for this.
         */
        if (is_ebb_event(event))
                local64_set(&event->hw.prev_count, 0);

        /*
         * 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;

        return err;
}

static int power_pmu_event_idx(struct perf_event *event)
{
        return event->hw.idx;
}

ssize_t power_events_sysfs_show(struct device *dev,
                                struct device_attribute *attr, char *page)
{
        struct perf_pmu_events_attr *pmu_attr;

        pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);

        return sprintf(page, "event=0x%02llx\n", pmu_attr->id);
}

static struct pmu power_pmu = {
        .pmu_enable     = power_pmu_enable,
        .pmu_disable    = power_pmu_disable,
        .event_init     = power_pmu_event_init,
        .add            = power_pmu_add,
        .del            = power_pmu_del,
        .start          = power_pmu_start,
        .stop           = power_pmu_stop,
        .read           = power_pmu_read,
        .start_txn      = power_pmu_start_txn,
        .cancel_txn     = power_pmu_cancel_txn,
        .commit_txn     = power_pmu_commit_txn,
        .event_idx      = power_pmu_event_idx,
        .sched_task     = power_pmu_sched_task,
};

#define PERF_SAMPLE_ADDR_TYPE  (PERF_SAMPLE_ADDR |              \
                                PERF_SAMPLE_PHYS_ADDR |         \
                                PERF_SAMPLE_DATA_PAGE_SIZE)
/*
 * 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)
{
        u64 period = event->hw.sample_period;
        s64 prev, delta, left;
        int record = 0;

        if (event->hw.state & PERF_HES_STOPPED) {
                write_pmc(event->hw.idx, 0);
                return;
        }

        /* we don't have to worry about interrupts here */
        prev = local64_read(&event->hw.prev_count);
        delta = check_and_compute_delta(prev, val);
        local64_add(delta, &event->count);

        /*
         * See if the total period for this event has expired,
         * and update for the next period.
         */
        val = 0;
        left = local64_read(&event->hw.period_left) - delta;
        if (delta == 0)
                left++;
        if (period) {
                if (left <= 0) {
                        left += period;
                        if (left <= 0)
                                left = period;

                        /*
                         * If address is not requested in the sample via
                         * PERF_SAMPLE_IP, just record that sample irrespective
                         * of SIAR valid check.
                         */
                        if (event->attr.sample_type & PERF_SAMPLE_IP)
                                record = siar_valid(regs);
                        else
                                record = 1;

                        event->hw.last_period = event->hw.sample_period;
                }
                if (left < 0x80000000LL)
                        val = 0x80000000LL - left;
        }

        write_pmc(event->hw.idx, val);
        local64_set(&event->hw.prev_count, val);
        local64_set(&event->hw.period_left, left);
        perf_event_update_userpage(event);

        /*
         * Due to hardware limitation, sometimes SIAR could sample a kernel
         * address even when freeze on supervisor state (kernel) is set in
         * MMCR2. Check attr.exclude_kernel and address to drop the sample in
         * these cases.
         */
        if (event->attr.exclude_kernel &&
            (event->attr.sample_type & PERF_SAMPLE_IP) &&
            is_kernel_addr(mfspr(SPRN_SIAR)))
                record = 0;

        /*
         * Finally record data if requested.
         */
        if (record) {
                struct perf_sample_data data;

                perf_sample_data_init(&data, ~0ULL, event->hw.last_period);

                if (event->attr.sample_type & PERF_SAMPLE_ADDR_TYPE)
                        perf_get_data_addr(event, regs, &data.addr);

                if (event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK) {
                        struct cpu_hw_events *cpuhw;
                        cpuhw = this_cpu_ptr(&cpu_hw_events);
                        power_pmu_bhrb_read(event, cpuhw);
                        perf_sample_save_brstack(&data, event, &cpuhw->bhrb_stack);
                }

                if (event->attr.sample_type & PERF_SAMPLE_DATA_SRC &&
                                                ppmu->get_mem_data_src) {
                        ppmu->get_mem_data_src(&data.data_src, ppmu->flags, regs);
                        data.sample_flags |= PERF_SAMPLE_DATA_SRC;
                }

                if (event->attr.sample_type & PERF_SAMPLE_WEIGHT_TYPE &&
                                                ppmu->get_mem_weight) {
                        ppmu->get_mem_weight(&data.weight.full, event->attr.sample_type);
                        data.sample_flags |= PERF_SAMPLE_WEIGHT_TYPE;
                }
                if (perf_event_overflow(event, &data, regs))
                        power_pmu_stop(event, 0);
        } else if (period) {
                /* Account for interrupt in case of invalid SIAR */
                if (perf_event_account_interrupt(event))
                        power_pmu_stop(event, 0);
        }
}

/*
 * 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 siar = mfspr(SPRN_SIAR);

        if (regs_use_siar(regs) && siar_valid(regs) && siar)
                return siar + perf_ip_adjust(regs);
        else
                return regs->nip;
}

static bool pmc_overflow_power7(unsigned long val)
{
        /*
         * Events on POWER7 can roll back if a speculative event doesn't
         * eventually complete. Unfortunately in some rare cases they will
         * raise a performance monitor exception. We need to catch this to
         * ensure we reset the PMC. In all cases the PMC will be 256 or less
         * cycles from overflow.
         *
         * We only do this if the first pass fails to find any overflowing
         * PMCs because a user might set a period of less than 256 and we
         * don't want to mistakenly reset them.
         */
        if ((0x80000000 - val) <= 256)
                return true;

        return false;
}

static bool pmc_overflow(unsigned long val)
{
        if ((int)val < 0)
                return true;

        return false;
}

/*
 * Performance monitor interrupt stuff
 */
static void __perf_event_interrupt(struct pt_regs *regs)
{
        int i, j;
        struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);
        struct perf_event *event;
        int found, active;

        if (cpuhw->n_limited)
                freeze_limited_counters(cpuhw, mfspr(SPRN_PMC5),
                                        mfspr(SPRN_PMC6));

        perf_read_regs(regs);

        /* Read all the PMCs since we'll need them a bunch of times */
        for (i = 0; i < ppmu->n_counter; ++i)
                cpuhw->pmcs[i] = read_pmc(i + 1);

        /* Try to find what caused the IRQ */
        found = 0;
        for (i = 0; i < ppmu->n_counter; ++i) {
                if (!pmc_overflow(cpuhw->pmcs[i]))
                        continue;
                if (is_limited_pmc(i + 1))
                        continue; /* these won't generate IRQs */
                /*
                 * We've found one that's overflowed.  For active
                 * counters we need to log this.  For inactive
                 * counters, we need to reset it anyway
                 */
                found = 1;
                active = 0;
                for (j = 0; j < cpuhw->n_events; ++j) {
                        event = cpuhw->event[j];
                        if (event->hw.idx == (i + 1)) {
                                active = 1;
                                record_and_restart(event, cpuhw->pmcs[i], regs);
                                break;
                        }
                }

                /*
                 * Clear PACA_IRQ_PMI in case it was set by
                 * set_pmi_irq_pending() when PMU was enabled
                 * after accounting for interrupts.
                 */
                clear_pmi_irq_pending();

                if (!active)
                        /* reset non active counters that have overflowed */
                        write_pmc(i + 1, 0);
        }
        if (!found && pvr_version_is(PVR_POWER7)) {
                /* check active counters for special buggy p7 overflow */
                for (i = 0; i < cpuhw->n_events; ++i) {
                        event = cpuhw->event[i];
                        if (!event->hw.idx || is_limited_pmc(event->hw.idx))
                                continue;
                        if (pmc_overflow_power7(cpuhw->pmcs[event->hw.idx - 1])) {
                                /* event has overflowed in a buggy way*/
                                found = 1;
                                record_and_restart(event,
                                                   cpuhw->pmcs[event->hw.idx - 1],
                                                   regs);
                        }
                }
        }

        /*
         * During system wide profiling or while specific CPU is monitored for an
         * event, some corner cases could cause PMC to overflow in idle path. This
         * will trigger a PMI after waking up from idle. Since counter values are _not_
         * saved/restored in idle path, can lead to below "Can't find PMC" message.
         */
        if (unlikely(!found) && !arch_irq_disabled_regs(regs))
                printk_ratelimited(KERN_WARNING "Can't find PMC that caused IRQ\n");

        /*
         * 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.mmcr0);

        /* Clear the cpuhw->pmcs */
        memset(&cpuhw->pmcs, 0, sizeof(cpuhw->pmcs));

}

static void perf_event_interrupt(struct pt_regs *regs)
{
        u64 start_clock = sched_clock();

        __perf_event_interrupt(regs);
        perf_sample_event_took(sched_clock() - start_clock);
}

static int power_pmu_prepare_cpu(unsigned int cpu)
{
        struct cpu_hw_events *cpuhw = &per_cpu(cpu_hw_events, cpu);

        if (ppmu) {
                memset(cpuhw, 0, sizeof(*cpuhw));
                cpuhw->mmcr.mmcr0 = MMCR0_FC;
        }
        return 0;
}

static ssize_t pmu_name_show(struct device *cdev,
                struct device_attribute *attr,
                char *buf)
{
        if (ppmu)
                return sysfs_emit(buf, "%s", ppmu->name);

        return 0;
}

static DEVICE_ATTR_RO(pmu_name);

static struct attribute *pmu_caps_attrs[] = {
        &dev_attr_pmu_name.attr,
        NULL
};

static const struct attribute_group pmu_caps_group = {
        .name  = "caps",
        .attrs = pmu_caps_attrs,
};

static const struct attribute_group *pmu_caps_groups[] = {
        &pmu_caps_group,
        NULL,
};

int __init 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);

        power_pmu.attr_groups = ppmu->attr_groups;

        if (ppmu->flags & PPMU_ARCH_207S)
                power_pmu.attr_update = pmu_caps_groups;

        power_pmu.capabilities |= (ppmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS);

#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 */

        perf_pmu_register(&power_pmu, "cpu", PERF_TYPE_RAW);
        cpuhp_setup_state(CPUHP_PERF_POWER, "perf/powerpc:prepare",
                          power_pmu_prepare_cpu, NULL);
        return 0;
}

#ifdef CONFIG_PPC64
static bool pmu_override = false;
static unsigned long pmu_override_val;
static void do_pmu_override(void *data)
{
        ppc_set_pmu_inuse(1);
        if (pmu_override_val)
                mtspr(SPRN_MMCR1, pmu_override_val);
        mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
}

static int __init init_ppc64_pmu(void)
{
        if (cpu_has_feature(CPU_FTR_HVMODE) && pmu_override) {
                pr_warn("disabling perf due to pmu_override= command line option.\n");
                on_each_cpu(do_pmu_override, NULL, 1);
                return 0;
        }

        /* run through all the pmu drivers one at a time */
        if (!init_power5_pmu())
                return 0;
        else if (!init_power5p_pmu())
                return 0;
        else if (!init_power6_pmu())
                return 0;
        else if (!init_power7_pmu())
                return 0;
        else if (!init_power8_pmu())
                return 0;
        else if (!init_power9_pmu())
                return 0;
        else if (!init_power10_pmu())
                return 0;
        else if (!init_ppc970_pmu())
                return 0;
        else
                return init_generic_compat_pmu();
}
early_initcall(init_ppc64_pmu);

static int __init pmu_setup(char *str)
{
        unsigned long val;

        if (!early_cpu_has_feature(CPU_FTR_HVMODE))
                return 0;

        pmu_override = true;

        if (kstrtoul(str, 0, &val))
                val = 0;

        pmu_override_val = val;

        return 1;
}
__setup("pmu_override=", pmu_setup);

#endif