s390/perf: add support for the CPU-Measurement Sampling Facility

Introduce a perf PMU, "cpum_sf", to support the CPU-Measurement
Sampling Facility.  You can control the sampling facility through
this perf PMU interfaces.  Perf sampling events are created for
hardware samples.

For details about the CPU-Measurement Sampling Facility, see
"The Load-Program-Parameter and the CPU-Measurement Facilities" (SA23-2260).

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

5 files changed, 1086 insertions, 13 deletions

diff --git a/arch/s390/include/asm/cpu_mf.h b/arch/s390/include/asm/cpu_mf.h
index f6dddeaad965..d707abc26157 100644
--- a/arch/s390/include/asm/cpu_mf.h
+++ b/arch/s390/include/asm/cpu_mf.h
@@ -210,6 +210,20 @@ static inline int lsctl(struct hws_lsctl_request_block *req)
 
 /* Sampling control helper functions */
 
+#include <linux/time.h>
+
+static inline unsigned long freq_to_sample_rate(struct hws_qsi_info_block *qsi,
+                                                unsigned long freq)
+{
+        return (USEC_PER_SEC / freq) * qsi->cpu_speed;
+}
+
+static inline unsigned long sample_rate_to_freq(struct hws_qsi_info_block *qsi,
+                                                unsigned long rate)
+{
+        return USEC_PER_SEC * qsi->cpu_speed / rate;
+}
+
 #define SDB_TE_ALERT_REQ_MASK   0x4000000000000000UL
 #define SDB_TE_BUFFER_FULL_MASK 0x8000000000000000UL
 
diff --git a/arch/s390/include/asm/perf_event.h b/arch/s390/include/asm/perf_event.h
index 34185020ae0a..b4eea25f379e 100644
--- a/arch/s390/include/asm/perf_event.h
+++ b/arch/s390/include/asm/perf_event.h
@@ -15,12 +15,13 @@
 #include <linux/device.h>
 #include <asm/cpu_mf.h>
 
-/* CPU-measurement counter facility */
-#define PERF_CPUM_CF_MAX_CTR            256
-
 /* Per-CPU flags for PMU states */
 #define PMU_F_RESERVED                  0x1000
 #define PMU_F_ENABLED                   0x2000
+#define PMU_F_IN_USE                    0x4000
+#define PMU_F_ERR_IBE                   0x0100
+#define PMU_F_ERR_LSDA                  0x0200
+#define PMU_F_ERR_MASK                  (PMU_F_ERR_IBE|PMU_F_ERR_LSDA)
 
 /* Perf defintions for PMU event attributes in sysfs */
 extern __init const struct attribute_group **cpumf_cf_event_group(void);
@@ -41,5 +42,15 @@ extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
 extern unsigned long perf_misc_flags(struct pt_regs *regs);
 #define perf_misc_flags(regs) perf_misc_flags(regs)
 
+/* Perf PMU definitions for the counter facility */
+#define PERF_CPUM_CF_MAX_CTR            256
+
+/* Perf PMU definitions for the sampling facility */
+#define PERF_CPUM_SF_MAX_CTR            1
+#define PERF_EVENT_CPUM_SF              0xB0000UL       /* Raw event ID */
+
+#define TEAR_REG(hwc)           ((hwc)->last_tag)
+#define SAMPL_RATE(hwc)         ((hwc)->event_base)
+
 #endif /* CONFIG_64BIT */
 #endif /* _ASM_S390_PERF_EVENT_H */
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 9f1e2adbd77e..1b3ac09c11b6 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -60,7 +60,7 @@ obj-$(CONFIG_FTRACE_SYSCALLS)  += ftrace.o
 obj-$(CONFIG_CRASH_DUMP)        += crash_dump.o
 
 ifdef CONFIG_64BIT
-obj-$(CONFIG_PERF_EVENTS)       += perf_event.o perf_cpum_cf.o \
+obj-$(CONFIG_PERF_EVENTS)       += perf_event.o perf_cpum_cf.o perf_cpum_sf.o \
                                                 perf_cpum_cf_events.o
 obj-y                           += runtime_instr.o cache.o
 endif
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
new file mode 100644
index 000000000000..141eca0917f4
--- /dev/null
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -0,0 +1,1024 @@
+/*
+ * Performance event support for the System z CPU-measurement Sampling Facility
+ *
+ * Copyright IBM Corp. 2013
+ * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ */
+#define KMSG_COMPONENT  "cpum_sf"
+#define pr_fmt(fmt)     KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/kernel_stat.h>
+#include <linux/perf_event.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/export.h>
+#include <asm/cpu_mf.h>
+#include <asm/irq.h>
+#include <asm/debug.h>
+#include <asm/timex.h>
+
+/* Minimum number of sample-data-block-tables:
+ * At least one table is required for the sampling buffer structure.
+ * A single table contains up to 511 pointers to sample-data-blocks.
+ */
+#define CPUM_SF_MIN_SDBT    1
+
+/* Minimum number of sample-data-blocks:
+ * The minimum designates a single page for sample-data-block, i.e.,
+ * up to 126 sample-data-blocks with a size of 32 bytes (bsdes).
+ */
+#define CPUM_SF_MIN_SDB     126
+
+/* Maximum number of sample-data-blocks:
+ * The maximum number designates approx. 256K per CPU including
+ * the given number of sample-data-blocks and taking the number
+ * of sample-data-block tables into account.
+ *
+ * Later, this number can be increased for extending the sampling
+ * buffer, for example, by factor 2 (512K) or 4 (1M).
+ */
+#define CPUM_SF_MAX_SDB     6471
+
+struct sf_buffer {
+        unsigned long    sdbt;      /* Sample-data-block-table origin */
+        /* buffer characteristics (required for buffer increments) */
+        unsigned long num_sdb;      /* Number of sample-data-blocks */
+        unsigned long    tail;      /* last sample-data-block-table */
+};
+
+struct cpu_hw_sf {
+        /* CPU-measurement sampling information block */
+        struct hws_qsi_info_block qsi;
+        struct hws_lsctl_request_block lsctl;
+        struct sf_buffer sfb;       /* Sampling buffer */
+        unsigned int flags;         /* Status flags */
+        struct perf_event *event;   /* Scheduled perf event */
+};
+static DEFINE_PER_CPU(struct cpu_hw_sf, cpu_hw_sf);
+
+/* Debug feature */
+static debug_info_t *sfdbg;
+
+/*
+ * sf_buffer_available() - Check for an allocated sampling buffer
+ */
+static int sf_buffer_available(struct cpu_hw_sf *cpuhw)
+{
+        return (cpuhw->sfb.sdbt) ? 1 : 0;
+}
+
+/*
+ * deallocate sampling facility buffer
+ */
+static void free_sampling_buffer(struct sf_buffer *sfb)
+{
+        unsigned long sdbt, *curr;
+
+        if (!sfb->sdbt)
+                return;
+
+        sdbt = sfb->sdbt;
+        curr = (unsigned long *) sdbt;
+
+        /* we'll free the SDBT after all SDBs are processed... */
+        while (1) {
+                if (!*curr || !sdbt)
+                        break;
+
+                /* watch for link entry reset if found */
+                if (is_link_entry(curr)) {
+                        curr = get_next_sdbt(curr);
+                        if (sdbt)
+                                free_page(sdbt);
+
+                        /* we are done if we reach the origin */
+                        if ((unsigned long) curr == sfb->sdbt)
+                                break;
+                        else
+                                sdbt = (unsigned long) curr;
+                } else {
+                        /* process SDB pointer */
+                        if (*curr) {
+                                free_page(*curr);
+                                curr++;
+                        }
+                }
+        }
+
+        debug_sprintf_event(sfdbg, 5,
+                            "free_sampling_buffer: freed sdbt=%0lx\n", sfb->sdbt);
+        memset(sfb, 0, sizeof(*sfb));
+}
+
+/*
+ * allocate_sampling_buffer() - allocate sampler memory
+ *
+ * Allocates and initializes a sampling buffer structure using the
+ * specified number of sample-data-blocks (SDB).  For each allocation,
+ * a 4K page is used.  The number of sample-data-block-tables (SDBT)
+ * are calculated from SDBs.
+ * Also set the ALERT_REQ mask in each SDBs trailer.
+ *
+ * Returns zero on success, non-zero otherwise.
+ */
+static int alloc_sampling_buffer(struct sf_buffer *sfb, unsigned long num_sdb)
+{
+        int j, k, rc;
+        unsigned long *sdbt, *tail, *trailer;
+        unsigned long sdb;
+        unsigned long num_sdbt, sdb_per_table;
+
+        if (sfb->sdbt)
+                return -EINVAL;
+        sfb->num_sdb = 0;
+
+        /* Compute the number of required sample-data-block-tables (SDBT) */
+        num_sdbt = num_sdb / ((PAGE_SIZE - 8) / 8);
+        if (num_sdbt < CPUM_SF_MIN_SDBT)
+                num_sdbt = CPUM_SF_MIN_SDBT;
+        sdb_per_table = (PAGE_SIZE - 8) / 8;
+
+        debug_sprintf_event(sfdbg, 4, "alloc_sampling_buffer: num_sdbt=%lu "
+                            "num_sdb=%lu sdb_per_table=%lu\n",
+                            num_sdbt, num_sdb, sdb_per_table);
+        sdbt = NULL;
+        tail = sdbt;
+
+        for (j = 0; j < num_sdbt; j++) {
+                sdbt = (unsigned long *) get_zeroed_page(GFP_KERNEL);
+                if (!sdbt) {
+                        rc = -ENOMEM;
+                        goto allocate_sdbt_error;
+                }
+
+                /* save origin of sample-data-block-table */
+                if (!sfb->sdbt)
+                        sfb->sdbt = (unsigned long) sdbt;
+
+                /* link current page to tail of chain */
+                if (tail)
+                        *tail = (unsigned long)(void *) sdbt + 1;
+
+                for (k = 0; k < num_sdb && k < sdb_per_table; k++) {
+                        /* get and set SDB page */
+                        sdb = get_zeroed_page(GFP_KERNEL);
+                        if (!sdb) {
+                                rc = -ENOMEM;
+                                goto allocate_sdbt_error;
+                        }
+                        *sdbt = sdb;
+                        trailer = trailer_entry_ptr(*sdbt);
+                        *trailer = SDB_TE_ALERT_REQ_MASK;
+                        sdbt++;
+                }
+                num_sdb -= k;
+                sfb->num_sdb += k;      /* count allocated sdb's */
+                tail = sdbt;
+        }
+
+        rc = 0;
+        if (tail)
+                *tail = sfb->sdbt + 1;
+        sfb->tail = (unsigned long) (void *)tail;
+
+allocate_sdbt_error:
+        if (rc)
+                free_sampling_buffer(sfb);
+        else
+                debug_sprintf_event(sfdbg, 4,
+                        "alloc_sampling_buffer: tear=%0lx dear=%0lx\n",
+                        sfb->sdbt, *(unsigned long *) sfb->sdbt);
+        return rc;
+}
+
+static int allocate_sdbt(struct cpu_hw_sf *cpuhw, const struct hw_perf_event *hwc)
+{
+        unsigned long n_sdb, freq;
+        unsigned long factor;
+
+        /* Calculate sampling buffers using 4K pages
+         *
+         *    1. Use frequency as input.  The samping buffer is designed for
+         *       a complete second.  This can be adjusted through the "factor"
+         *       variable.
+         *       In any case, alloc_sampling_buffer() sets the Alert Request
+         *       Control indicator to trigger measurement-alert to harvest
+         *       sample-data-blocks (sdb).
+         *
+         *    2. Compute the number of sample-data-blocks and ensure a minimum
+         *       of CPUM_SF_MIN_SDB.  Also ensure the upper limit does not
+         *       exceed CPUM_SF_MAX_SDB.  See also the remarks for these
+         *       symbolic constants.
+         *
+         *    3. Compute number of pages used for the sample-data-block-table
+         *       and ensure a minimum of CPUM_SF_MIN_SDBT (at minimum one table
+         *       to manage up to 511 sample-data-blocks).
+         */
+        freq = sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc));
+        factor = 1;
+        n_sdb = DIV_ROUND_UP(freq, factor * ((PAGE_SIZE-64) / cpuhw->qsi.bsdes));
+        if (n_sdb < CPUM_SF_MIN_SDB)
+                n_sdb = CPUM_SF_MIN_SDB;
+
+        /* Return if there is already a sampling buffer allocated.
+         * XXX Remove this later and check number of available and
+         * required sdb's and, if necessary, increase the sampling buffer.
+         */
+        if (sf_buffer_available(cpuhw))
+                return 0;
+
+        debug_sprintf_event(sfdbg, 3,
+                            "allocate_sdbt: rate=%lu f=%lu sdb=%lu/%i cpuhw=%p\n",
+                            SAMPL_RATE(hwc), freq, n_sdb, CPUM_SF_MAX_SDB, cpuhw);
+
+        return alloc_sampling_buffer(&cpuhw->sfb,
+                               min_t(unsigned long, n_sdb, CPUM_SF_MAX_SDB));
+}
+
+
+/* Number of perf events counting hardware events */
+static atomic_t num_events;
+/* Used to avoid races in calling reserve/release_cpumf_hardware */
+static DEFINE_MUTEX(pmc_reserve_mutex);
+
+/*
+ * sf_disable() - Switch off sampling facility
+ */
+static int sf_disable(void)
+{
+        struct hws_lsctl_request_block sreq;
+
+        memset(&sreq, 0, sizeof(sreq));
+        return lsctl(&sreq);
+}
+
+
+#define PMC_INIT      0
+#define PMC_RELEASE   1
+static void setup_pmc_cpu(void *flags)
+{
+        int err;
+        struct cpu_hw_sf *cpusf = &__get_cpu_var(cpu_hw_sf);
+
+        /* XXX Improve error handling and pass a flag in the *flags
+         *     variable to indicate failures.  Alternatively, ignore
+         *     (print) errors here and let the PMU functions fail if
+         *     the per-cpu PMU_F_RESERVED flag is not.
+         */
+        err = 0;
+        switch (*((int *) flags)) {
+        case PMC_INIT:
+                memset(cpusf, 0, sizeof(*cpusf));
+                err = qsi(&cpusf->qsi);
+                if (err)
+                        break;
+                cpusf->flags |= PMU_F_RESERVED;
+                err = sf_disable();
+                if (err)
+                        pr_err("Switching off the sampling facility failed "
+                               "with rc=%i\n", err);
+                debug_sprintf_event(sfdbg, 5,
+                                    "setup_pmc_cpu: initialized: cpuhw=%p\n", cpusf);
+                break;
+        case PMC_RELEASE:
+                cpusf->flags &= ~PMU_F_RESERVED;
+                err = sf_disable();
+                if (err) {
+                        pr_err("Switching off the sampling facility failed "
+                               "with rc=%i\n", err);
+                } else {
+                        if (cpusf->sfb.sdbt)
+                                free_sampling_buffer(&cpusf->sfb);
+                }
+                debug_sprintf_event(sfdbg, 5,
+                                    "setup_pmc_cpu: released: cpuhw=%p\n", cpusf);
+                break;
+        }
+}
+
+static void release_pmc_hardware(void)
+{
+        int flags = PMC_RELEASE;
+
+        irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
+        on_each_cpu(setup_pmc_cpu, &flags, 1);
+}
+
+static int reserve_pmc_hardware(void)
+{
+        int flags = PMC_INIT;
+
+        on_each_cpu(setup_pmc_cpu, &flags, 1);
+        irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
+
+        return 0;
+}
+
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+        /* Release PMC if this is the last perf 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);
+        }
+}
+
+static void hw_init_period(struct hw_perf_event *hwc, u64 period)
+{
+        hwc->sample_period = period;
+        hwc->last_period = hwc->sample_period;
+        local64_set(&hwc->period_left, hwc->sample_period);
+}
+
+static void hw_reset_registers(struct hw_perf_event *hwc,
+                               unsigned long sdbt_origin)
+{
+        TEAR_REG(hwc) = sdbt_origin;          /* (re)set to first sdb table */
+}
+
+static unsigned long hw_limit_rate(const struct hws_qsi_info_block *si,
+                                   unsigned long rate)
+{
+        if (rate < si->min_sampl_rate)
+                return si->min_sampl_rate;
+        if (rate > si->max_sampl_rate)
+                return si->max_sampl_rate;
+        return rate;
+}
+
+static int __hw_perf_event_init(struct perf_event *event)
+{
+        struct cpu_hw_sf *cpuhw;
+        struct hws_qsi_info_block si;
+        struct perf_event_attr *attr = &event->attr;
+        struct hw_perf_event *hwc = &event->hw;
+        unsigned long rate;
+        int cpu, err;
+
+        /* Reserve CPU-measurement sampling facility */
+        err = 0;
+        if (!atomic_inc_not_zero(&num_events)) {
+                mutex_lock(&pmc_reserve_mutex);
+                if (atomic_read(&num_events) == 0 && reserve_pmc_hardware())
+                        err = -EBUSY;
+                else
+                        atomic_inc(&num_events);
+                mutex_unlock(&pmc_reserve_mutex);
+        }
+        event->destroy = hw_perf_event_destroy;
+
+        if (err)
+                goto out;
+
+        /* Access per-CPU sampling information (query sampling info) */
+        /*
+         * The event->cpu value can be -1 to count on every CPU, for example,
+         * when attaching to a task.  If this is specified, use the query
+         * sampling info from the current CPU, otherwise use event->cpu to
+         * retrieve the per-CPU information.
+         * Later, cpuhw indicates whether to allocate sampling buffers for a
+         * particular CPU (cpuhw!=NULL) or each online CPU (cpuw==NULL).
+         */
+        memset(&si, 0, sizeof(si));
+        cpuhw = NULL;
+        if (event->cpu == -1)
+                qsi(&si);
+        else {
+                /* Event is pinned to a particular CPU, retrieve the per-CPU
+                 * sampling structure for accessing the CPU-specific QSI.
+                 */
+                cpuhw = &per_cpu(cpu_hw_sf, event->cpu);
+                si = cpuhw->qsi;
+        }
+
+        /* Check sampling facility authorization and, if not authorized,
+         * fall back to other PMUs.  It is safe to check any CPU because
+         * the authorization is identical for all configured CPUs.
+         */
+        if (!si.as) {
+                err = -ENOENT;
+                goto out;
+        }
+
+        /* The sampling information (si) contains information about the
+         * min/max sampling intervals and the CPU speed.  So calculate the
+         * correct sampling interval and avoid the whole period adjust
+         * feedback loop.
+         */
+        rate = 0;
+        if (attr->freq) {
+                rate = freq_to_sample_rate(&si, attr->sample_freq);
+                rate = hw_limit_rate(&si, rate);
+                attr->freq = 0;
+                attr->sample_period = rate;
+        } else {
+                /* The min/max sampling rates specifies the valid range
+                 * of sample periods.  If the specified sample period is
+                 * out of range, limit the period to the range boundary.
+                 */
+                rate = hw_limit_rate(&si, hwc->sample_period);
+
+                /* The perf core maintains a maximum sample rate that is
+                 * configurable through the sysctl interface.  Ensure the
+                 * sampling rate does not exceed this value.  This also helps
+                 * to avoid throttling when pushing samples with
+                 * perf_event_overflow().
+                 */
+                if (sample_rate_to_freq(&si, rate) >
+                      sysctl_perf_event_sample_rate) {
+                        err = -EINVAL;
+                        debug_sprintf_event(sfdbg, 1, "Sampling rate exceeds maximum perf sample rate\n");
+                        goto out;
+                }
+        }
+        SAMPL_RATE(hwc) = rate;
+        hw_init_period(hwc, SAMPL_RATE(hwc));
+
+        /* Allocate the per-CPU sampling buffer using the CPU information
+         * from the event.  If the event is not pinned to a particular
+         * CPU (event->cpu == -1; or cpuhw == NULL), allocate sampling
+         * buffers for each online CPU.
+         */
+        if (cpuhw)
+                /* Event is pinned to a particular CPU */
+                err = allocate_sdbt(cpuhw, hwc);
+        else {
+                /* Event is not pinned, allocate sampling buffer on
+                 * each online CPU
+                 */
+                for_each_online_cpu(cpu) {
+                        cpuhw = &per_cpu(cpu_hw_sf, cpu);
+                        err = allocate_sdbt(cpuhw, hwc);
+                        if (err)
+                                break;
+                }
+        }
+out:
+        return err;
+}
+
+static int cpumsf_pmu_event_init(struct perf_event *event)
+{
+        int err;
+
+        if (event->attr.type != PERF_TYPE_RAW)
+                return -ENOENT;
+
+        if (event->attr.config != PERF_EVENT_CPUM_SF)
+                return -ENOENT;
+
+        if (event->cpu >= nr_cpumask_bits ||
+            (event->cpu >= 0 && !cpu_online(event->cpu)))
+                return -ENODEV;
+
+        err = __hw_perf_event_init(event);
+        if (unlikely(err))
+                if (event->destroy)
+                        event->destroy(event);
+        return err;
+}
+
+static void cpumsf_pmu_enable(struct pmu *pmu)
+{
+        struct cpu_hw_sf *cpuhw = &__get_cpu_var(cpu_hw_sf);
+        int err;
+
+        if (cpuhw->flags & PMU_F_ENABLED)
+                return;
+
+        if (cpuhw->flags & PMU_F_ERR_MASK)
+                return;
+
+        cpuhw->flags |= PMU_F_ENABLED;
+        barrier();
+
+        err = lsctl(&cpuhw->lsctl);
+        if (err) {
+                cpuhw->flags &= ~PMU_F_ENABLED;
+                pr_err("Loading sampling controls failed: op=%i err=%i\n",
+                        1, err);
+                return;
+        }
+
+        debug_sprintf_event(sfdbg, 6, "pmu_enable: es=%i cs=%i tear=%p dear=%p\n",
+                            cpuhw->lsctl.es, cpuhw->lsctl.cs,
+                            (void *) cpuhw->lsctl.tear, (void *) cpuhw->lsctl.dear);
+}
+
+static void cpumsf_pmu_disable(struct pmu *pmu)
+{
+        struct cpu_hw_sf *cpuhw = &__get_cpu_var(cpu_hw_sf);
+        struct hws_lsctl_request_block inactive;
+        struct hws_qsi_info_block si;
+        int err;
+
+        if (!(cpuhw->flags & PMU_F_ENABLED))
+                return;
+
+        if (cpuhw->flags & PMU_F_ERR_MASK)
+                return;
+
+        /* Switch off sampling activation control */
+        inactive = cpuhw->lsctl;
+        inactive.cs = 0;
+
+        err = lsctl(&inactive);
+        if (err) {
+                pr_err("Loading sampling controls failed: op=%i err=%i\n",
+                        2, err);
+                return;
+        }
+
+        /* Save state of TEAR and DEAR register contents */
+        if (!qsi(&si)) {
+                /* TEAR/DEAR values are valid only if the sampling facility is
+                 * enabled.  Note that cpumsf_pmu_disable() might be called even
+                 * for a disabled sampling facility because cpumsf_pmu_enable()
+                 * controls the enable/disable state.
+                 */
+                if (si.es) {
+                        cpuhw->lsctl.tear = si.tear;
+                        cpuhw->lsctl.dear = si.dear;
+                }
+        } else
+                debug_sprintf_event(sfdbg, 3, "cpumsf_pmu_disable: "
+                                    "qsi() failed with err=%i\n", err);
+
+        cpuhw->flags &= ~PMU_F_ENABLED;
+}
+
+/* perf_push_sample() - Push samples to perf
+ * @event:      The perf event
+ * @sample:     Hardware sample data
+ *
+ * Use the hardware sample data to create perf event sample.  The sample
+ * is the pushed to the event subsystem and the function checks for
+ * possible event overflows.  If an event overflow occurs, the PMU is
+ * stopped.
+ *
+ * Return non-zero if an event overflow occurred.
+ */
+static int perf_push_sample(struct perf_event *event,
+                            struct hws_data_entry *sample)
+{
+        int overflow;
+        struct pt_regs regs;
+        struct perf_sample_data data;
+
+        /* Skip samples that are invalid or for which the instruction address
+         * is not predictable.  For the latter, the wait-state bit is set.
+         */
+        if (sample->I || sample->W)
+                return 0;
+
+        perf_sample_data_init(&data, 0, event->hw.last_period);
+
+        memset(&regs, 0, sizeof(regs));
+        regs.psw.addr = sample->ia;
+        if (sample->T)
+                regs.psw.mask |= PSW_MASK_DAT;
+        if (sample->W)
+                regs.psw.mask |= PSW_MASK_WAIT;
+        if (sample->P)
+                regs.psw.mask |= PSW_MASK_PSTATE;
+        switch (sample->AS) {
+        case 0x0:
+                regs.psw.mask |= PSW_ASC_PRIMARY;
+                break;
+        case 0x1:
+                regs.psw.mask |= PSW_ASC_ACCREG;
+                break;
+        case 0x2:
+                regs.psw.mask |= PSW_ASC_SECONDARY;
+                break;
+        case 0x3:
+                regs.psw.mask |= PSW_ASC_HOME;
+                break;
+        }
+
+        overflow = 0;
+        if (perf_event_overflow(event, &data, &regs)) {
+                overflow = 1;
+                event->pmu->stop(event, 0);
+                debug_sprintf_event(sfdbg, 4, "perf_push_sample: PMU stopped"
+                                    " because of an event overflow\n");
+        }
+        perf_event_update_userpage(event);
+
+        return overflow;
+}
+
+static void perf_event_count_update(struct perf_event *event, u64 count)
+{
+        local64_add(count, &event->count);
+}
+
+/* hw_collect_samples() - Walk through a sample-data-block and collect samples
+ * @event:      The perf event
+ * @sdbt:       Sample-data-block table
+ * @overflow:   Event overflow counter
+ *
+ * Walks through a sample-data-block and collects hardware sample-data that is
+ * pushed to the perf event subsystem.  The overflow reports the number of
+ * samples that has been discarded due to an event overflow.
+ */
+static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
+                               unsigned long long *overflow)
+{
+        struct hws_data_entry *sample;
+        unsigned long *trailer;
+
+        trailer = trailer_entry_ptr(*sdbt);
+        sample = (struct hws_data_entry *) *sdbt;
+        while ((unsigned long *) sample < trailer) {
+                /* Check for an empty sample */
+                if (!sample->def)
+                        break;
+
+                /* Update perf event period */
+                perf_event_count_update(event, SAMPL_RATE(&event->hw));
+
+                /* Check for basic sampling mode */
+                if (sample->def == 0x0001) {
+                        /* If an event overflow occurred, the PMU is stopped to
+                         * throttle event delivery.  Remaining sample data is
+                         * discarded.
+                         */
+                        if (!*overflow)
+                                *overflow = perf_push_sample(event, sample);
+                        else
+                                /* Count discarded samples */
+                                *overflow += 1;
+                } else
+                        /* Sample slot is not yet written or other record */
+                        debug_sprintf_event(sfdbg, 5, "hw_collect_samples: "
+                                            "Unknown sample data entry format:"
+                                            " %i\n", sample->def);
+
+                /* Reset sample slot and advance to next sample */
+                sample->def = 0;
+                sample++;
+        }
+}
+
+/* hw_perf_event_update() - Process sampling buffer
+ * @event:      The perf event
+ * @flush_all:  Flag to also flush partially filled sample-data-blocks
+ *
+ * Processes the sampling buffer and create perf event samples.
+ * The sampling buffer position are retrieved and saved in the TEAR_REG
+ * register of the specified perf event.
+ *
+ * Only full sample-data-blocks are processed.  Specify the flash_all flag
+ * to also walk through partially filled sample-data-blocks.
+ *
+ */
+static void hw_perf_event_update(struct perf_event *event, int flush_all)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        struct hws_trailer_entry *te;
+        unsigned long *sdbt;
+        unsigned long long event_overflow, sampl_overflow;
+        int done;
+
+        sdbt = (unsigned long *) TEAR_REG(hwc);
+        done = event_overflow = sampl_overflow = 0;
+        while (!done) {
+                /* Get the trailer entry of the sample-data-block */
+                te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);
+
+                /* Leave loop if no more work to do (block full indicator) */
+                if (!te->f) {
+                        done = 1;
+                        if (!flush_all)
+                                break;
+                }
+
+                /* Check sample overflow count */
+                if (te->overflow) {
+                        /* Increment sample overflow counter */
+                        sampl_overflow += te->overflow;
+
+                        /* XXX: If an sample overflow occurs, increase the
+                         *      sampling buffer.  Set a "realloc" flag because
+                         *      the sampler must be re-enabled for changing
+                         *      the sample-data-block-table content.
+                         */
+                }
+
+                /* Timestamps are valid for full sample-data-blocks only */
+                debug_sprintf_event(sfdbg, 6, "hw_perf_event_update: sdbt=%p "
+                                    "overflow=%llu timestamp=0x%llx\n",
+                                    sdbt, te->overflow,
+                                    (te->f) ? te->timestamp : 0ULL);
+
+                /* Collect all samples from a single sample-data-block and
+                 * flag if an (perf) event overflow happened.  If so, the PMU
+                 * is stopped and remaining samples will be discarded.
+                 */
+                hw_collect_samples(event, sdbt, &event_overflow);
+
+                /* Reset trailer */
+                xchg(&te->overflow, 0);
+                xchg((unsigned char *) te, 0x40);
+
+                /* Advance to next sample-data-block */
+                sdbt++;
+                if (is_link_entry(sdbt))
+                        sdbt = get_next_sdbt(sdbt);
+
+                /* Update event hardware registers */
+                TEAR_REG(hwc) = (unsigned long) sdbt;
+
+                /* Stop processing sample-data if all samples of the current
+                 * sample-data-block were flushed even if it was not full.
+                 */
+                if (flush_all && done)
+                        break;
+
+                /* If an event overflow happened, discard samples by
+                 * processing any remaining sample-data-blocks.
+                 */
+                if (event_overflow)
+                        flush_all = 1;
+        }
+
+        if (sampl_overflow || event_overflow)
+                debug_sprintf_event(sfdbg, 4, "hw_perf_event_update: "
+                                    "overflow stats: sample=%llu event=%llu\n",
+                                    sampl_overflow, event_overflow);
+}
+
+static void cpumsf_pmu_read(struct perf_event *event)
+{
+        /* Nothing to do ... updates are interrupt-driven */
+}
+
+/* Activate sampling control.
+ * Next call of pmu_enable() starts sampling.
+ */
+static void cpumsf_pmu_start(struct perf_event *event, int flags)
+{
+        struct cpu_hw_sf *cpuhw = &__get_cpu_var(cpu_hw_sf);
+
+        if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+                return;
+
+        if (flags & PERF_EF_RELOAD)
+                WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
+
+        perf_pmu_disable(event->pmu);
+        event->hw.state = 0;
+        cpuhw->lsctl.cs = 1;
+        perf_pmu_enable(event->pmu);
+}
+
+/* Deactivate sampling control.
+ * Next call of pmu_enable() stops sampling.
+ */
+static void cpumsf_pmu_stop(struct perf_event *event, int flags)
+{
+        struct cpu_hw_sf *cpuhw = &__get_cpu_var(cpu_hw_sf);
+
+        if (event->hw.state & PERF_HES_STOPPED)
+                return;
+
+        perf_pmu_disable(event->pmu);
+        cpuhw->lsctl.cs = 0;
+        event->hw.state |= PERF_HES_STOPPED;
+
+        if ((flags & PERF_EF_UPDATE) && !(event->hw.state & PERF_HES_UPTODATE)) {
+                hw_perf_event_update(event, 1);
+                event->hw.state |= PERF_HES_UPTODATE;
+        }
+        perf_pmu_enable(event->pmu);
+}
+
+static int cpumsf_pmu_add(struct perf_event *event, int flags)
+{
+        struct cpu_hw_sf *cpuhw = &__get_cpu_var(cpu_hw_sf);
+        int err;
+
+        if (cpuhw->flags & PMU_F_IN_USE)
+                return -EAGAIN;
+
+        if (!cpuhw->sfb.sdbt)
+                return -EINVAL;
+
+        err = 0;
+        perf_pmu_disable(event->pmu);
+
+        event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+
+        /* Set up sampling controls.  Always program the sampling register
+         * using the SDB-table start.  Reset TEAR_REG event hardware register
+         * that is used by hw_perf_event_update() to store the sampling buffer
+         * position after samples have been flushed.
+         */
+        cpuhw->lsctl.s = 0;
+        cpuhw->lsctl.h = 1;
+        cpuhw->lsctl.tear = cpuhw->sfb.sdbt;
+        cpuhw->lsctl.dear = *(unsigned long *) cpuhw->sfb.sdbt;
+        cpuhw->lsctl.interval = SAMPL_RATE(&event->hw);
+        hw_reset_registers(&event->hw, cpuhw->sfb.sdbt);
+
+        /* Ensure sampling functions are in the disabled state.  If disabled,
+         * switch on sampling enable control. */
+        if (WARN_ON_ONCE(cpuhw->lsctl.es == 1)) {
+                err = -EAGAIN;
+                goto out;
+        }
+        cpuhw->lsctl.es = 1;
+
+        /* Set in_use flag and store event */
+        event->hw.idx = 0;        /* only one sampling event per CPU supported */
+        cpuhw->event = event;
+        cpuhw->flags |= PMU_F_IN_USE;
+
+        if (flags & PERF_EF_START)
+                cpumsf_pmu_start(event, PERF_EF_RELOAD);
+out:
+        perf_event_update_userpage(event);
+        perf_pmu_enable(event->pmu);
+        return err;
+}
+
+static void cpumsf_pmu_del(struct perf_event *event, int flags)
+{
+        struct cpu_hw_sf *cpuhw = &__get_cpu_var(cpu_hw_sf);
+
+        perf_pmu_disable(event->pmu);
+        cpumsf_pmu_stop(event, PERF_EF_UPDATE);
+
+        cpuhw->lsctl.es = 0;
+        cpuhw->flags &= ~PMU_F_IN_USE;
+        cpuhw->event = NULL;
+
+        perf_event_update_userpage(event);
+        perf_pmu_enable(event->pmu);
+}
+
+static int cpumsf_pmu_event_idx(struct perf_event *event)
+{
+        return event->hw.idx;
+}
+
+CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC, PERF_EVENT_CPUM_SF);
+
+static struct attribute *cpumsf_pmu_events_attr[] = {
+        CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC),
+        NULL,
+};
+
+PMU_FORMAT_ATTR(event, "config:0-63");
+
+static struct attribute *cpumsf_pmu_format_attr[] = {
+        &format_attr_event.attr,
+        NULL,
+};
+
+static struct attribute_group cpumsf_pmu_events_group = {
+        .name = "events",
+        .attrs = cpumsf_pmu_events_attr,
+};
+static struct attribute_group cpumsf_pmu_format_group = {
+        .name = "format",
+        .attrs = cpumsf_pmu_format_attr,
+};
+static const struct attribute_group *cpumsf_pmu_attr_groups[] = {
+        &cpumsf_pmu_events_group,
+        &cpumsf_pmu_format_group,
+        NULL,
+};
+
+static struct pmu cpumf_sampling = {
+        .pmu_enable   = cpumsf_pmu_enable,
+        .pmu_disable  = cpumsf_pmu_disable,
+
+        .event_init   = cpumsf_pmu_event_init,
+        .add          = cpumsf_pmu_add,
+        .del          = cpumsf_pmu_del,
+
+        .start        = cpumsf_pmu_start,
+        .stop         = cpumsf_pmu_stop,
+        .read         = cpumsf_pmu_read,
+
+        .event_idx    = cpumsf_pmu_event_idx,
+        .attr_groups  = cpumsf_pmu_attr_groups,
+};
+
+static void cpumf_measurement_alert(struct ext_code ext_code,
+                                    unsigned int alert, unsigned long unused)
+{
+        struct cpu_hw_sf *cpuhw;
+
+        if (!(alert & CPU_MF_INT_SF_MASK))
+                return;
+        inc_irq_stat(IRQEXT_CMS);
+        cpuhw = &__get_cpu_var(cpu_hw_sf);
+
+        /* Measurement alerts are shared and might happen when the PMU
+         * is not reserved.  Ignore these alerts in this case. */
+        if (!(cpuhw->flags & PMU_F_RESERVED))
+                return;
+
+        /* The processing below must take care of multiple alert events that
+         * might be indicated concurrently. */
+
+        /* Program alert request */
+        if (alert & CPU_MF_INT_SF_PRA) {
+                if (cpuhw->flags & PMU_F_IN_USE)
+                        hw_perf_event_update(cpuhw->event, 0);
+                else
+                        WARN_ON_ONCE(!(cpuhw->flags & PMU_F_IN_USE));
+        }
+
+        /* Report measurement alerts only for non-PRA codes */
+        if (alert != CPU_MF_INT_SF_PRA)
+                debug_sprintf_event(sfdbg, 6, "measurement alert: 0x%x\n", alert);
+
+        /* Sampling authorization change request */
+        if (alert & CPU_MF_INT_SF_SACA)
+                qsi(&cpuhw->qsi);
+
+        /* Loss of sample data due to high-priority machine activities */
+        if (alert & CPU_MF_INT_SF_LSDA) {
+                pr_err("Sample data was lost\n");
+                cpuhw->flags |= PMU_F_ERR_LSDA;
+                sf_disable();
+        }
+
+        /* Invalid sampling buffer entry */
+        if (alert & (CPU_MF_INT_SF_IAE|CPU_MF_INT_SF_ISE)) {
+                pr_err("A sampling buffer entry is incorrect (alert=0x%x)\n",
+                       alert);
+                cpuhw->flags |= PMU_F_ERR_IBE;
+                sf_disable();
+        }
+}
+
+static int __cpuinit cpumf_pmu_notifier(struct notifier_block *self,
+                                        unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (long) hcpu;
+        int flags;
+
+        /* Ignore the notification if no events are scheduled on the PMU.
+         * This might be racy...
+         */
+        if (!atomic_read(&num_events))
+                return NOTIFY_OK;
+
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_ONLINE:
+        case CPU_ONLINE_FROZEN:
+                flags = PMC_INIT;
+                smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
+                break;
+        case CPU_DOWN_PREPARE:
+                flags = PMC_RELEASE;
+                smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
+                break;
+        default:
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+static int __init init_cpum_sampling_pmu(void)
+{
+        int err;
+
+        if (!cpum_sf_avail())
+                return -ENODEV;
+
+        sfdbg = debug_register(KMSG_COMPONENT, 2, 1, 80);
+        if (!sfdbg)
+                pr_err("Registering for s390dbf failed\n");
+        debug_register_view(sfdbg, &debug_sprintf_view);
+
+        err = register_external_interrupt(0x1407, cpumf_measurement_alert);
+        if (err) {
+                pr_err("Failed to register for CPU-measurement alerts\n");
+                goto out;
+        }
+
+        err = perf_pmu_register(&cpumf_sampling, "cpum_sf", PERF_TYPE_RAW);
+        if (err) {
+                pr_err("Failed to register cpum_sf pmu\n");
+                unregister_external_interrupt(0x1407, cpumf_measurement_alert);
+                goto out;
+        }
+        perf_cpu_notifier(cpumf_pmu_notifier);
+out:
+        return err;
+}
+arch_initcall(init_cpum_sampling_pmu);
diff --git a/arch/s390/kernel/perf_event.c b/arch/s390/kernel/perf_event.c
index 4c1d336ce941..b9843ba9829f 100644
--- a/arch/s390/kernel/perf_event.c
+++ b/arch/s390/kernel/perf_event.c
@@ -16,6 +16,7 @@
 #include <linux/kvm_host.h>
 #include <linux/percpu.h>
 #include <linux/export.h>
+#include <linux/spinlock.h>
 #include <linux/sysfs.h>
 #include <asm/irq.h>
 #include <asm/cpu_mf.h>
@@ -36,6 +37,8 @@ int perf_num_counters(void)
 
         if (cpum_cf_avail())
                 num += PERF_CPUM_CF_MAX_CTR;
+        if (cpum_sf_avail())
+                num += PERF_CPUM_SF_MAX_CTR;
 
         return num;
 }
@@ -93,24 +96,45 @@ unsigned long perf_misc_flags(struct pt_regs *regs)
                                : PERF_RECORD_MISC_KERNEL;
 }
 
-void perf_event_print_debug(void)
+void print_debug_cf(void)
 {
         struct cpumf_ctr_info cf_info;
-        unsigned long flags;
-        int cpu;
-
-        if (!cpum_cf_avail())
-                return;
-
-        local_irq_save(flags);
+        int cpu = smp_processor_id();
 
-        cpu = smp_processor_id();
         memset(&cf_info, 0, sizeof(cf_info));
         if (!qctri(&cf_info))
                 pr_info("CPU[%i] CPUM_CF: ver=%u.%u A=%04x E=%04x C=%04x\n",
                         cpu, cf_info.cfvn, cf_info.csvn,
                         cf_info.auth_ctl, cf_info.enable_ctl, cf_info.act_ctl);
+}
+
+static void print_debug_sf(void)
+{
+        struct hws_qsi_info_block si;
+        int cpu = smp_processor_id();
+
+        memset(&si, 0, sizeof(si));
+        if (qsi(&si)) {
+                pr_err("CPU[%i]: CPM_SF: qsi failed\n");
+                return;
+        }
+
+        pr_info("CPU[%i]: CPM_SF: as=%i es=%i cs=%i bsdes=%i dsdes=%i"
+                " min=%i max=%i cpu_speed=%i tear=%p dear=%p\n",
+                cpu, si.as, si.es, si.cs, si.bsdes, si.dsdes,
+                si.min_sampl_rate, si.max_sampl_rate, si.cpu_speed,
+                si.tear, si.dear);
+}
+
+void perf_event_print_debug(void)
+{
+        unsigned long flags;
 
+        local_irq_save(flags);
+        if (cpum_cf_avail())
+                print_debug_cf();
+        if (cpum_sf_avail())
+                print_debug_sf();
         local_irq_restore(flags);
 }