Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2254 insertions, 0 deletions

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
new file mode 100644
index 000000000..ce886a035
--- /dev/null
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -0,0 +1,2254 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Performance event support for the System z CPU-measurement Sampling Facility
+ *
+ * Copyright IBM Corp. 2013, 2018
+ * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
+ */
+#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/pid.h>
+#include <linux/notifier.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/moduleparam.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
+
+/* Number of sample-data-blocks per sample-data-block-table (SDBT):
+ * A table contains SDB pointers (8 bytes) and one table-link entry
+ * that points to the origin of the next SDBT.
+ */
+#define CPUM_SF_SDB_PER_TABLE	((PAGE_SIZE - 8) / 8)
+
+/* Maximum page offset for an SDBT table-link entry:
+ * If this page offset is reached, a table-link entry to the next SDBT
+ * must be added.
+ */
+#define CPUM_SF_SDBT_TL_OFFSET	(CPUM_SF_SDB_PER_TABLE * 8)
+static inline int require_table_link(const void *sdbt)
+{
+	return ((unsigned long) sdbt & ~PAGE_MASK) == CPUM_SF_SDBT_TL_OFFSET;
+}
+
+/* Minimum and maximum sampling buffer sizes:
+ *
+ * This number represents the maximum size of the sampling buffer taking
+ * the number of sample-data-block-tables into account.  Note that these
+ * numbers apply to the basic-sampling function only.
+ * The maximum number of SDBs is increased by CPUM_SF_SDB_DIAG_FACTOR if
+ * the diagnostic-sampling function is active.
+ *
+ * Sampling buffer size		Buffer characteristics
+ * ---------------------------------------------------
+ *	 64KB		    ==	  16 pages (4KB per page)
+ *				   1 page  for SDB-tables
+ *				  15 pages for SDBs
+ *
+ *  32MB		    ==	8192 pages (4KB per page)
+ *				  16 pages for SDB-tables
+ *				8176 pages for SDBs
+ */
+static unsigned long __read_mostly CPUM_SF_MIN_SDB = 15;
+static unsigned long __read_mostly CPUM_SF_MAX_SDB = 8176;
+static unsigned long __read_mostly CPUM_SF_SDB_DIAG_FACTOR = 1;
+
+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 num_sdbt;	    /* Number of sample-data-block-tables */
+	unsigned long	 *tail;	    /* last sample-data-block-table */
+};
+
+struct aux_buffer {
+	struct sf_buffer sfb;
+	unsigned long head;	   /* index of SDB of buffer head */
+	unsigned long alert_mark;  /* index of SDB of alert request position */
+	unsigned long empty_mark;  /* mark of SDB not marked full */
+	unsigned long *sdb_index;  /* SDB address for fast lookup */
+	unsigned long *sdbt_index; /* SDBT address for fast lookup */
+};
+
+struct cpu_hw_sf {
+	/* CPU-measurement sampling information block */
+	struct hws_qsi_info_block qsi;
+	/* CPU-measurement sampling control block */
+	struct hws_lsctl_request_block lsctl;
+	struct sf_buffer sfb;	    /* Sampling buffer */
+	unsigned int flags;	    /* Status flags */
+	struct perf_event *event;   /* Scheduled perf event */
+	struct perf_output_handle handle; /* AUX buffer output handle */
+};
+static DEFINE_PER_CPU(struct cpu_hw_sf, cpu_hw_sf);
+
+/* Debug feature */
+static debug_info_t *sfdbg;
+
+/*
+ * 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);
+}
+
+/*
+ * sf_buffer_available() - Check for an allocated sampling buffer
+ */
+static int sf_buffer_available(struct cpu_hw_sf *cpuhw)
+{
+	return !!cpuhw->sfb.sdbt;
+}
+
+/*
+ * 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 = sdbt;
+
+	/* Free the SDBT after all SDBs are processed... */
+	while (1) {
+		if (!*curr || !sdbt)
+			break;
+
+		/* Process table-link entries */
+		if (is_link_entry(curr)) {
+			curr = get_next_sdbt(curr);
+			if (sdbt)
+				free_page((unsigned long) sdbt);
+
+			/* If the origin is reached, sampling buffer is freed */
+			if (curr == sfb->sdbt)
+				break;
+			else
+				sdbt = curr;
+		} else {
+			/* Process SDB pointer */
+			if (*curr) {
+				free_page(*curr);
+				curr++;
+			}
+		}
+	}
+
+	debug_sprintf_event(sfdbg, 5, "%s: freed sdbt %#lx\n", __func__,
+			    (unsigned long)sfb->sdbt);
+	memset(sfb, 0, sizeof(*sfb));
+}
+
+static int alloc_sample_data_block(unsigned long *sdbt, gfp_t gfp_flags)
+{
+	struct hws_trailer_entry *te;
+	unsigned long sdb;
+
+	/* Allocate and initialize sample-data-block */
+	sdb = get_zeroed_page(gfp_flags);
+	if (!sdb)
+		return -ENOMEM;
+	te = (struct hws_trailer_entry *)trailer_entry_ptr(sdb);
+	te->header.a = 1;
+
+	/* Link SDB into the sample-data-block-table */
+	*sdbt = sdb;
+
+	return 0;
+}
+
+/*
+ * realloc_sampling_buffer() - extend sampler memory
+ *
+ * Allocates new sample-data-blocks and adds them to the specified sampling
+ * buffer memory.
+ *
+ * Important: This modifies the sampling buffer and must be called when the
+ *	      sampling facility is disabled.
+ *
+ * Returns zero on success, non-zero otherwise.
+ */
+static int realloc_sampling_buffer(struct sf_buffer *sfb,
+				   unsigned long num_sdb, gfp_t gfp_flags)
+{
+	int i, rc;
+	unsigned long *new, *tail, *tail_prev = NULL;
+
+	if (!sfb->sdbt || !sfb->tail)
+		return -EINVAL;
+
+	if (!is_link_entry(sfb->tail))
+		return -EINVAL;
+
+	/* Append to the existing sampling buffer, overwriting the table-link
+	 * register.
+	 * The tail variables always points to the "tail" (last and table-link)
+	 * entry in an SDB-table.
+	 */
+	tail = sfb->tail;
+
+	/* Do a sanity check whether the table-link entry points to
+	 * the sampling buffer origin.
+	 */
+	if (sfb->sdbt != get_next_sdbt(tail)) {
+		debug_sprintf_event(sfdbg, 3, "%s: "
+				    "sampling buffer is not linked: origin %#lx"
+				    " tail %#lx\n", __func__,
+				    (unsigned long)sfb->sdbt,
+				    (unsigned long)tail);
+		return -EINVAL;
+	}
+
+	/* Allocate remaining SDBs */
+	rc = 0;
+	for (i = 0; i < num_sdb; i++) {
+		/* Allocate a new SDB-table if it is full. */
+		if (require_table_link(tail)) {
+			new = (unsigned long *) get_zeroed_page(gfp_flags);
+			if (!new) {
+				rc = -ENOMEM;
+				break;
+			}
+			sfb->num_sdbt++;
+			/* Link current page to tail of chain */
+			*tail = (unsigned long)(void *) new + 1;
+			tail_prev = tail;
+			tail = new;
+		}
+
+		/* Allocate a new sample-data-block.
+		 * If there is not enough memory, stop the realloc process
+		 * and simply use what was allocated.  If this is a temporary
+		 * issue, a new realloc call (if required) might succeed.
+		 */
+		rc = alloc_sample_data_block(tail, gfp_flags);
+		if (rc) {
+			/* Undo last SDBT. An SDBT with no SDB at its first
+			 * entry but with an SDBT entry instead can not be
+			 * handled by the interrupt handler code.
+			 * Avoid this situation.
+			 */
+			if (tail_prev) {
+				sfb->num_sdbt--;
+				free_page((unsigned long) new);
+				tail = tail_prev;
+			}
+			break;
+		}
+		sfb->num_sdb++;
+		tail++;
+		tail_prev = new = NULL;	/* Allocated at least one SBD */
+	}
+
+	/* Link sampling buffer to its origin */
+	*tail = (unsigned long) sfb->sdbt + 1;
+	sfb->tail = tail;
+
+	debug_sprintf_event(sfdbg, 4, "%s: new buffer"
+			    " settings: sdbt %lu sdb %lu\n", __func__,
+			    sfb->num_sdbt, sfb->num_sdb);
+	return rc;
+}
+
+/*
+ * 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 rc;
+
+	if (sfb->sdbt)
+		return -EINVAL;
+
+	/* Allocate the sample-data-block-table origin */
+	sfb->sdbt = (unsigned long *) get_zeroed_page(GFP_KERNEL);
+	if (!sfb->sdbt)
+		return -ENOMEM;
+	sfb->num_sdb = 0;
+	sfb->num_sdbt = 1;
+
+	/* Link the table origin to point to itself to prepare for
+	 * realloc_sampling_buffer() invocation.
+	 */
+	sfb->tail = sfb->sdbt;
+	*sfb->tail = (unsigned long)(void *) sfb->sdbt + 1;
+
+	/* Allocate requested number of sample-data-blocks */
+	rc = realloc_sampling_buffer(sfb, num_sdb, GFP_KERNEL);
+	if (rc) {
+		free_sampling_buffer(sfb);
+		debug_sprintf_event(sfdbg, 4, "%s: "
+			"realloc_sampling_buffer failed with rc %i\n",
+			__func__, rc);
+	} else
+		debug_sprintf_event(sfdbg, 4,
+			"%s: tear %#lx dear %#lx\n", __func__,
+			(unsigned long)sfb->sdbt, (unsigned long)*sfb->sdbt);
+	return rc;
+}
+
+static void sfb_set_limits(unsigned long min, unsigned long max)
+{
+	struct hws_qsi_info_block si;
+
+	CPUM_SF_MIN_SDB = min;
+	CPUM_SF_MAX_SDB = max;
+
+	memset(&si, 0, sizeof(si));
+	if (!qsi(&si))
+		CPUM_SF_SDB_DIAG_FACTOR = DIV_ROUND_UP(si.dsdes, si.bsdes);
+}
+
+static unsigned long sfb_max_limit(struct hw_perf_event *hwc)
+{
+	return SAMPL_DIAG_MODE(hwc) ? CPUM_SF_MAX_SDB * CPUM_SF_SDB_DIAG_FACTOR
+				    : CPUM_SF_MAX_SDB;
+}
+
+static unsigned long sfb_pending_allocs(struct sf_buffer *sfb,
+					struct hw_perf_event *hwc)
+{
+	if (!sfb->sdbt)
+		return SFB_ALLOC_REG(hwc);
+	if (SFB_ALLOC_REG(hwc) > sfb->num_sdb)
+		return SFB_ALLOC_REG(hwc) - sfb->num_sdb;
+	return 0;
+}
+
+static int sfb_has_pending_allocs(struct sf_buffer *sfb,
+				   struct hw_perf_event *hwc)
+{
+	return sfb_pending_allocs(sfb, hwc) > 0;
+}
+
+static void sfb_account_allocs(unsigned long num, struct hw_perf_event *hwc)
+{
+	/* Limit the number of SDBs to not exceed the maximum */
+	num = min_t(unsigned long, num, sfb_max_limit(hwc) - SFB_ALLOC_REG(hwc));
+	if (num)
+		SFB_ALLOC_REG(hwc) += num;
+}
+
+static void sfb_init_allocs(unsigned long num, struct hw_perf_event *hwc)
+{
+	SFB_ALLOC_REG(hwc) = 0;
+	sfb_account_allocs(num, hwc);
+}
+
+static void deallocate_buffers(struct cpu_hw_sf *cpuhw)
+{
+	if (cpuhw->sfb.sdbt)
+		free_sampling_buffer(&cpuhw->sfb);
+}
+
+static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc)
+{
+	unsigned long n_sdb, freq;
+	size_t sample_size;
+
+	/* Calculate sampling buffers using 4K pages
+	 *
+	 *    1. The sampling size is 32 bytes for basic sampling. This size
+	 *	 is the same for all machine types. Diagnostic
+	 *	 sampling uses auxlilary data buffer setup which provides the
+	 *	 memory for SDBs using linux common code auxiliary trace
+	 *	 setup.
+	 *
+	 *    2. Function alloc_sampling_buffer() sets the Alert Request
+	 *	 Control indicator to trigger a measurement-alert to harvest
+	 *	 sample-data-blocks (SDB). This is done per SDB. This
+	 *	 measurement alert interrupt fires quick enough to handle
+	 *	 one SDB, on very high frequency and work loads there might
+	 *	 be 2 to 3 SBDs available for sample processing.
+	 *	 Currently there is no need for setup alert request on every
+	 *	 n-th page. This is counterproductive as one IRQ triggers
+	 *	 a very high number of samples to be processed at one IRQ.
+	 *
+	 *    3. Use the sampling frequency as input.
+	 *	 Compute the number of SDBs and ensure a minimum
+	 *	 of CPUM_SF_MIN_SDB.  Depending on frequency add some more
+	 *	 SDBs to handle a higher sampling rate.
+	 *	 Use a minimum of CPUM_SF_MIN_SDB and allow for 100 samples
+	 *	 (one SDB) for every 10000 HZ frequency increment.
+	 *
+	 *    4. Compute the number of sample-data-block-tables (SDBT) and
+	 *	 ensure a minimum of CPUM_SF_MIN_SDBT (one table can manage up
+	 *	 to 511 SDBs).
+	 */
+	sample_size = sizeof(struct hws_basic_entry);
+	freq = sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc));
+	n_sdb = CPUM_SF_MIN_SDB + DIV_ROUND_UP(freq, 10000);
+
+	/* If there is already a sampling buffer allocated, it is very likely
+	 * that the sampling facility is enabled too.  If the event to be
+	 * initialized requires a greater sampling buffer, the allocation must
+	 * be postponed.  Changing the sampling buffer requires the sampling
+	 * facility to be in the disabled state.  So, account the number of
+	 * required SDBs and let cpumsf_pmu_enable() resize the buffer just
+	 * before the event is started.
+	 */
+	sfb_init_allocs(n_sdb, hwc);
+	if (sf_buffer_available(cpuhw))
+		return 0;
+
+	debug_sprintf_event(sfdbg, 3,
+			    "%s: rate %lu f %lu sdb %lu/%lu"
+			    " sample_size %lu cpuhw %p\n", __func__,
+			    SAMPL_RATE(hwc), freq, n_sdb, sfb_max_limit(hwc),
+			    sample_size, cpuhw);
+
+	return alloc_sampling_buffer(&cpuhw->sfb,
+				     sfb_pending_allocs(&cpuhw->sfb, hwc));
+}
+
+static unsigned long min_percent(unsigned int percent, unsigned long base,
+				 unsigned long min)
+{
+	return min_t(unsigned long, min, DIV_ROUND_UP(percent * base, 100));
+}
+
+static unsigned long compute_sfb_extent(unsigned long ratio, unsigned long base)
+{
+	/* Use a percentage-based approach to extend the sampling facility
+	 * buffer.  Accept up to 5% sample data loss.
+	 * Vary the extents between 1% to 5% of the current number of
+	 * sample-data-blocks.
+	 */
+	if (ratio <= 5)
+		return 0;
+	if (ratio <= 25)
+		return min_percent(1, base, 1);
+	if (ratio <= 50)
+		return min_percent(1, base, 1);
+	if (ratio <= 75)
+		return min_percent(2, base, 2);
+	if (ratio <= 100)
+		return min_percent(3, base, 3);
+	if (ratio <= 250)
+		return min_percent(4, base, 4);
+
+	return min_percent(5, base, 8);
+}
+
+static void sfb_account_overflows(struct cpu_hw_sf *cpuhw,
+				  struct hw_perf_event *hwc)
+{
+	unsigned long ratio, num;
+
+	if (!OVERFLOW_REG(hwc))
+		return;
+
+	/* The sample_overflow contains the average number of sample data
+	 * that has been lost because sample-data-blocks were full.
+	 *
+	 * Calculate the total number of sample data entries that has been
+	 * discarded.  Then calculate the ratio of lost samples to total samples
+	 * per second in percent.
+	 */
+	ratio = DIV_ROUND_UP(100 * OVERFLOW_REG(hwc) * cpuhw->sfb.num_sdb,
+			     sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc)));
+
+	/* Compute number of sample-data-blocks */
+	num = compute_sfb_extent(ratio, cpuhw->sfb.num_sdb);
+	if (num)
+		sfb_account_allocs(num, hwc);
+
+	debug_sprintf_event(sfdbg, 5, "%s: overflow %llu ratio %lu num %lu\n",
+			    __func__, OVERFLOW_REG(hwc), ratio, num);
+	OVERFLOW_REG(hwc) = 0;
+}
+
+/* extend_sampling_buffer() - Extend sampling buffer
+ * @sfb:	Sampling buffer structure (for local CPU)
+ * @hwc:	Perf event hardware structure
+ *
+ * Use this function to extend the sampling buffer based on the overflow counter
+ * and postponed allocation extents stored in the specified Perf event hardware.
+ *
+ * Important: This function disables the sampling facility in order to safely
+ *	      change the sampling buffer structure.  Do not call this function
+ *	      when the PMU is active.
+ */
+static void extend_sampling_buffer(struct sf_buffer *sfb,
+				   struct hw_perf_event *hwc)
+{
+	unsigned long num, num_old;
+	int rc;
+
+	num = sfb_pending_allocs(sfb, hwc);
+	if (!num)
+		return;
+	num_old = sfb->num_sdb;
+
+	/* Disable the sampling facility to reset any states and also
+	 * clear pending measurement alerts.
+	 */
+	sf_disable();
+
+	/* Extend the sampling buffer.
+	 * This memory allocation typically happens in an atomic context when
+	 * called by perf.  Because this is a reallocation, it is fine if the
+	 * new SDB-request cannot be satisfied immediately.
+	 */
+	rc = realloc_sampling_buffer(sfb, num, GFP_ATOMIC);
+	if (rc)
+		debug_sprintf_event(sfdbg, 5, "%s: realloc failed with rc %i\n",
+				    __func__, rc);
+
+	if (sfb_has_pending_allocs(sfb, hwc))
+		debug_sprintf_event(sfdbg, 5, "%s: "
+				    "req %lu alloc %lu remaining %lu\n",
+				    __func__, num, sfb->num_sdb - num_old,
+				    sfb_pending_allocs(sfb, hwc));
+}
+
+/* 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);
+
+#define PMC_INIT      0
+#define PMC_RELEASE   1
+#define PMC_FAILURE   2
+static void setup_pmc_cpu(void *flags)
+{
+	int err;
+	struct cpu_hw_sf *cpusf = this_cpu_ptr(&cpu_hw_sf);
+
+	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,
+				    "%s: initialized: cpuhw %p\n", __func__,
+				    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
+			deallocate_buffers(cpusf);
+		debug_sprintf_event(sfdbg, 5,
+				    "%s: released: cpuhw %p\n", __func__,
+				    cpusf);
+		break;
+	}
+	if (err)
+		*((int *) flags) |= PMC_FAILURE;
+}
+
+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);
+	if (flags & PMC_FAILURE) {
+		release_pmc_hardware();
+		return -ENODEV;
+	}
+	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 unsigned long hw_limit_rate(const struct hws_qsi_info_block *si,
+				   unsigned long rate)
+{
+	return clamp_t(unsigned long, rate,
+		       si->min_sampl_rate, si->max_sampl_rate);
+}
+
+static u32 cpumsf_pid_type(struct perf_event *event,
+			   u32 pid, enum pid_type type)
+{
+	struct task_struct *tsk;
+
+	/* Idle process */
+	if (!pid)
+		goto out;
+
+	tsk = find_task_by_pid_ns(pid, &init_pid_ns);
+	pid = -1;
+	if (tsk) {
+		/*
+		 * Only top level events contain the pid namespace in which
+		 * they are created.
+		 */
+		if (event->parent)
+			event = event->parent;
+		pid = __task_pid_nr_ns(tsk, type, event->ns);
+		/*
+		 * See also 1d953111b648
+		 * "perf/core: Don't report zero PIDs for exiting tasks".
+		 */
+		if (!pid && !pid_alive(tsk))
+			pid = -1;
+	}
+out:
+	return pid;
+}
+
+static void cpumsf_output_event_pid(struct perf_event *event,
+				    struct perf_sample_data *data,
+				    struct pt_regs *regs)
+{
+	u32 pid;
+	struct perf_event_header header;
+	struct perf_output_handle handle;
+
+	/*
+	 * Obtain the PID from the basic-sampling data entry and
+	 * correct the data->tid_entry.pid value.
+	 */
+	pid = data->tid_entry.pid;
+
+	/* Protect callchain buffers, tasks */
+	rcu_read_lock();
+
+	perf_prepare_sample(&header, data, event, regs);
+	if (perf_output_begin(&handle, data, event, header.size))
+		goto out;
+
+	/* Update the process ID (see also kernel/events/core.c) */
+	data->tid_entry.pid = cpumsf_pid_type(event, pid, PIDTYPE_TGID);
+	data->tid_entry.tid = cpumsf_pid_type(event, pid, PIDTYPE_PID);
+
+	perf_output_sample(&handle, &header, data, event);
+	perf_output_end(&handle);
+out:
+	rcu_read_unlock();
+}
+
+static unsigned long getrate(bool freq, unsigned long sample,
+			     struct hws_qsi_info_block *si)
+{
+	unsigned long rate;
+
+	if (freq) {
+		rate = freq_to_sample_rate(si, sample);
+		rate = hw_limit_rate(si, 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, sample);
+
+		/* 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) {
+			debug_sprintf_event(sfdbg, 1, "%s: "
+					    "Sampling rate exceeds maximum "
+					    "perf sample rate\n", __func__);
+			rate = 0;
+		}
+	}
+	return rate;
+}
+
+/* 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.
+ *
+ * Since the CPU Measurement sampling facility can not handle frequency
+ * calculate the sampling interval when frequency is specified using
+ * this formula:
+ *	interval := cpu_speed * 1000000 / sample_freq
+ *
+ * Returns errno on bad input and zero on success with parameter interval
+ * set to the correct sampling rate.
+ *
+ * Note: This function turns off freq bit to avoid calling function
+ * perf_adjust_period(). This causes frequency adjustment in the common
+ * code part which causes tremendous variations in the counter values.
+ */
+static int __hw_perf_event_init_rate(struct perf_event *event,
+				     struct hws_qsi_info_block *si)
+{
+	struct perf_event_attr *attr = &event->attr;
+	struct hw_perf_event *hwc = &event->hw;
+	unsigned long rate;
+
+	if (attr->freq) {
+		if (!attr->sample_freq)
+			return -EINVAL;
+		rate = getrate(attr->freq, attr->sample_freq, si);
+		attr->freq = 0;		/* Don't call  perf_adjust_period() */
+		SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_FREQ_MODE;
+	} else {
+		rate = getrate(attr->freq, attr->sample_period, si);
+		if (!rate)
+			return -EINVAL;
+	}
+	attr->sample_period = rate;
+	SAMPL_RATE(hwc) = rate;
+	hw_init_period(hwc, SAMPL_RATE(hwc));
+	debug_sprintf_event(sfdbg, 4, "%s: cpu %d period %#llx freq %d,%#lx\n",
+			    __func__, event->cpu, event->attr.sample_period,
+			    event->attr.freq, SAMPLE_FREQ_MODE(hwc));
+	return 0;
+}
+
+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;
+	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;
+	}
+
+	if (si.ribm & CPU_MF_SF_RIBM_NOTAV) {
+		pr_warn("CPU Measurement Facility sampling is temporarily not available\n");
+		err = -EBUSY;
+		goto out;
+	}
+
+	/* Always enable basic sampling */
+	SAMPL_FLAGS(hwc) = PERF_CPUM_SF_BASIC_MODE;
+
+	/* Check if diagnostic sampling is requested.  Deny if the required
+	 * sampling authorization is missing.
+	 */
+	if (attr->config == PERF_EVENT_CPUM_SF_DIAG) {
+		if (!si.ad) {
+			err = -EPERM;
+			goto out;
+		}
+		SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_DIAG_MODE;
+	}
+
+	/* Check and set other sampling flags */
+	if (attr->config1 & PERF_CPUM_SF_FULL_BLOCKS)
+		SAMPL_FLAGS(hwc) |= PERF_CPUM_SF_FULL_BLOCKS;
+
+	err =  __hw_perf_event_init_rate(event, &si);
+	if (err)
+		goto out;
+
+	/* Initialize sample data overflow accounting */
+	hwc->extra_reg.reg = REG_OVERFLOW;
+	OVERFLOW_REG(hwc) = 0;
+
+	/* Use AUX buffer. No need to allocate it by ourself */
+	if (attr->config == PERF_EVENT_CPUM_SF_DIAG)
+		return 0;
+
+	/* 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_buffers(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_buffers(cpuhw, hwc);
+			if (err)
+				break;
+		}
+	}
+
+	/* If PID/TID sampling is active, replace the default overflow
+	 * handler to extract and resolve the PIDs from the basic-sampling
+	 * data entries.
+	 */
+	if (event->attr.sample_type & PERF_SAMPLE_TID)
+		if (is_default_overflow_handler(event))
+			event->overflow_handler = cpumsf_output_event_pid;
+out:
+	return err;
+}
+
+static bool is_callchain_event(struct perf_event *event)
+{
+	u64 sample_type = event->attr.sample_type;
+
+	return sample_type & (PERF_SAMPLE_CALLCHAIN | PERF_SAMPLE_REGS_USER |
+			      PERF_SAMPLE_STACK_USER);
+}
+
+static int cpumsf_pmu_event_init(struct perf_event *event)
+{
+	int err;
+
+	/* No support for taken branch sampling */
+	/* No support for callchain, stacks and registers */
+	if (has_branch_stack(event) || is_callchain_event(event))
+		return -EOPNOTSUPP;
+
+	switch (event->attr.type) {
+	case PERF_TYPE_RAW:
+		if ((event->attr.config != PERF_EVENT_CPUM_SF) &&
+		    (event->attr.config != PERF_EVENT_CPUM_SF_DIAG))
+			return -ENOENT;
+		break;
+	case PERF_TYPE_HARDWARE:
+		/* Support sampling of CPU cycles in addition to the
+		 * counter facility.  However, the counter facility
+		 * is more precise and, hence, restrict this PMU to
+		 * sampling events only.
+		 */
+		if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES)
+			return -ENOENT;
+		if (!is_sampling_event(event))
+			return -ENOENT;
+		break;
+	default:
+		return -ENOENT;
+	}
+
+	/* Check online status of the CPU to which the event is pinned */
+	if (event->cpu >= 0 && !cpu_online(event->cpu))
+		return -ENODEV;
+
+	/* Force reset of idle/hv excludes regardless of what the
+	 * user requested.
+	 */
+	if (event->attr.exclude_hv)
+		event->attr.exclude_hv = 0;
+	if (event->attr.exclude_idle)
+		event->attr.exclude_idle = 0;
+
+	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 = this_cpu_ptr(&cpu_hw_sf);
+	struct hw_perf_event *hwc;
+	int err;
+
+	if (cpuhw->flags & PMU_F_ENABLED)
+		return;
+
+	if (cpuhw->flags & PMU_F_ERR_MASK)
+		return;
+
+	/* Check whether to extent the sampling buffer.
+	 *
+	 * Two conditions trigger an increase of the sampling buffer for a
+	 * perf event:
+	 *    1. Postponed buffer allocations from the event initialization.
+	 *    2. Sampling overflows that contribute to pending allocations.
+	 *
+	 * Note that the extend_sampling_buffer() function disables the sampling
+	 * facility, but it can be fully re-enabled using sampling controls that
+	 * have been saved in cpumsf_pmu_disable().
+	 */
+	if (cpuhw->event) {
+		hwc = &cpuhw->event->hw;
+		if (!(SAMPL_DIAG_MODE(hwc))) {
+			/*
+			 * Account number of overflow-designated
+			 * buffer extents
+			 */
+			sfb_account_overflows(cpuhw, hwc);
+			extend_sampling_buffer(&cpuhw->sfb, hwc);
+		}
+		/* Rate may be adjusted with ioctl() */
+		cpuhw->lsctl.interval = SAMPL_RATE(&cpuhw->event->hw);
+	}
+
+	/* (Re)enable the PMU and sampling facility */
+	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;
+	}
+
+	/* Load current program parameter */
+	lpp(&S390_lowcore.lpp);
+
+	debug_sprintf_event(sfdbg, 6, "%s: es %i cs %i ed %i cd %i "
+			    "interval %#lx tear %#lx dear %#lx\n", __func__,
+			    cpuhw->lsctl.es, cpuhw->lsctl.cs, cpuhw->lsctl.ed,
+			    cpuhw->lsctl.cd, cpuhw->lsctl.interval,
+			    cpuhw->lsctl.tear, cpuhw->lsctl.dear);
+}
+
+static void cpumsf_pmu_disable(struct pmu *pmu)
+{
+	struct cpu_hw_sf *cpuhw = this_cpu_ptr(&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;
+	inactive.cd = 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 */
+	err = qsi(&si);
+	if (!err) {
+		/* 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, "%s: qsi() failed with err %i\n",
+				    __func__, err);
+
+	cpuhw->flags &= ~PMU_F_ENABLED;
+}
+
+/* perf_exclude_event() - Filter event
+ * @event:	The perf event
+ * @regs:	pt_regs structure
+ * @sde_regs:	Sample-data-entry (sde) regs structure
+ *
+ * Filter perf events according to their exclude specification.
+ *
+ * Return non-zero if the event shall be excluded.
+ */
+static int perf_exclude_event(struct perf_event *event, struct pt_regs *regs,
+			      struct perf_sf_sde_regs *sde_regs)
+{
+	if (event->attr.exclude_user && user_mode(regs))
+		return 1;
+	if (event->attr.exclude_kernel && !user_mode(regs))
+		return 1;
+	if (event->attr.exclude_guest && sde_regs->in_guest)
+		return 1;
+	if (event->attr.exclude_host && !sde_regs->in_guest)
+		return 1;
+	return 0;
+}
+
+/* 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_basic_entry *basic)
+{
+	int overflow;
+	struct pt_regs regs;
+	struct perf_sf_sde_regs *sde_regs;
+	struct perf_sample_data data;
+
+	/* Setup perf sample */
+	perf_sample_data_init(&data, 0, event->hw.last_period);
+
+	/* Setup pt_regs to look like an CPU-measurement external interrupt
+	 * using the Program Request Alert code.  The regs.int_parm_long
+	 * field which is unused contains additional sample-data-entry related
+	 * indicators.
+	 */
+	memset(&regs, 0, sizeof(regs));
+	regs.int_code = 0x1407;
+	regs.int_parm = CPU_MF_INT_SF_PRA;
+	sde_regs = (struct perf_sf_sde_regs *) &regs.int_parm_long;
+
+	psw_bits(regs.psw).ia	= basic->ia;
+	psw_bits(regs.psw).dat	= basic->T;
+	psw_bits(regs.psw).wait = basic->W;
+	psw_bits(regs.psw).pstate = basic->P;
+	psw_bits(regs.psw).as	= basic->AS;
+
+	/*
+	 * Use the hardware provided configuration level to decide if the
+	 * sample belongs to a guest or host. If that is not available,
+	 * fall back to the following heuristics:
+	 * A non-zero guest program parameter always indicates a guest
+	 * sample. Some early samples or samples from guests without
+	 * lpp usage would be misaccounted to the host. We use the asn
+	 * value as an addon heuristic to detect most of these guest samples.
+	 * If the value differs from 0xffff (the host value), we assume to
+	 * be a KVM guest.
+	 */
+	switch (basic->CL) {
+	case 1: /* logical partition */
+		sde_regs->in_guest = 0;
+		break;
+	case 2: /* virtual machine */
+		sde_regs->in_guest = 1;
+		break;
+	default: /* old machine, use heuristics */
+		if (basic->gpp || basic->prim_asn != 0xffff)
+			sde_regs->in_guest = 1;
+		break;
+	}
+
+	/*
+	 * Store the PID value from the sample-data-entry to be
+	 * processed and resolved by cpumsf_output_event_pid().
+	 */
+	data.tid_entry.pid = basic->hpp & LPP_PID_MASK;
+
+	overflow = 0;
+	if (perf_exclude_event(event, &regs, sde_regs))
+		goto out;
+	if (perf_event_overflow(event, &data, &regs)) {
+		overflow = 1;
+		event->pmu->stop(event, 0);
+	}
+	perf_event_update_userpage(event);
+out:
+	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 sampling data entries that are
+ * then pushed to the perf event subsystem.  Depending on the sampling function,
+ * there can be either basic-sampling or combined-sampling data entries.  A
+ * combined-sampling data entry consists of a basic- and a diagnostic-sampling
+ * data entry.	The sampling function is determined by the flags in the perf
+ * event hardware structure.  The function always works with a combined-sampling
+ * data entry but ignores the the diagnostic portion if it is not available.
+ *
+ * Note that the implementation focuses on basic-sampling data entries and, if
+ * such an entry is not valid, the entire combined-sampling data entry is
+ * ignored.
+ *
+ * The overflow variables counts the number of samples that has been discarded
+ * due to a perf event overflow.
+ */
+static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
+			       unsigned long long *overflow)
+{
+	struct hws_trailer_entry *te;
+	struct hws_basic_entry *sample;
+
+	te = (struct hws_trailer_entry *) trailer_entry_ptr(*sdbt);
+	sample = (struct hws_basic_entry *) *sdbt;
+	while ((unsigned long *) sample < (unsigned long *) te) {
+		/* Check for an empty sample */
+		if (!sample->def || sample->LS)
+			break;
+
+		/* Update perf event period */
+		perf_event_count_update(event, SAMPL_RATE(&event->hw));
+
+		/* Check whether sample is valid */
+		if (sample->def == 0x0001) {
+			/* If an event overflow occurred, the PMU is stopped to
+			 * throttle event delivery.  Remaining sample data is
+			 * discarded.
+			 */
+			if (!*overflow) {
+				/* Check whether sample is consistent */
+				if (sample->I == 0 && sample->W == 0) {
+					/* Deliver sample data to perf */
+					*overflow = perf_push_sample(event,
+								     sample);
+				}
+			} else
+				/* Count discarded samples */
+				*overflow += 1;
+		} else {
+			debug_sprintf_event(sfdbg, 4,
+					    "%s: Found unknown"
+					    " sampling data entry: te->f %i"
+					    " basic.def %#4x (%p)\n", __func__,
+					    te->header.f, sample->def, sample);
+			/* Sample slot is not yet written or other record.
+			 *
+			 * This condition can occur if the buffer was reused
+			 * from a combined basic- and diagnostic-sampling.
+			 * If only basic-sampling is then active, entries are
+			 * written into the larger diagnostic entries.
+			 * This is typically the case for sample-data-blocks
+			 * that are not full.  Stop processing if the first
+			 * invalid format was detected.
+			 */
+			if (!te->header.f)
+				break;
+		}
+
+		/* Reset sample slot and advance to next sample */
+		sample->def = 0;
+		sample++;
+	}
+}
+
+static inline __uint128_t __cdsg(__uint128_t *ptr, __uint128_t old, __uint128_t new)
+{
+	asm volatile(
+		"	cdsg	%[old],%[new],%[ptr]\n"
+		: [old] "+d" (old), [ptr] "+QS" (*ptr)
+		: [new] "d" (new)
+		: "memory", "cc");
+	return old;
+}
+
+/* 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.  It is ignored
+ * if PERF_CPUM_SF_FULL_BLOCKS is set.	The PERF_CPUM_SF_FULL_BLOCKS flag
+ * enforces the processing of full sample-data-blocks only (trailer entries
+ * with the block-full-indicator bit set).
+ */
+static void hw_perf_event_update(struct perf_event *event, int flush_all)
+{
+	unsigned long long event_overflow, sampl_overflow, num_sdb;
+	union hws_trailer_header old, prev, new;
+	struct hw_perf_event *hwc = &event->hw;
+	struct hws_trailer_entry *te;
+	unsigned long *sdbt;
+	int done;
+
+	/*
+	 * AUX buffer is used when in diagnostic sampling mode.
+	 * No perf events/samples are created.
+	 */
+	if (SAMPL_DIAG_MODE(&event->hw))
+		return;
+
+	if (flush_all && SDB_FULL_BLOCKS(hwc))
+		flush_all = 0;
+
+	sdbt = (unsigned long *) TEAR_REG(hwc);
+	done = event_overflow = sampl_overflow = num_sdb = 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->header.f) {
+			done = 1;
+			if (!flush_all)
+				break;
+		}
+
+		/* Check the sample overflow count */
+		if (te->header.overflow)
+			/* Account sample overflows and, if a particular limit
+			 * is reached, extend the sampling buffer.
+			 * For details, see sfb_account_overflows().
+			 */
+			sampl_overflow += te->header.overflow;
+
+		/* Timestamps are valid for full sample-data-blocks only */
+		debug_sprintf_event(sfdbg, 6, "%s: sdbt %#lx "
+				    "overflow %llu timestamp %#llx\n",
+				    __func__, (unsigned long)sdbt, te->header.overflow,
+				    (te->header.f) ? trailer_timestamp(te) : 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);
+		num_sdb++;
+
+		/* Reset trailer (using compare-double-and-swap) */
+		/* READ_ONCE() 16 byte header */
+		prev.val = __cdsg(&te->header.val, 0, 0);
+		do {
+			old.val = prev.val;
+			new.val = prev.val;
+			new.f = 0;
+			new.a = 1;
+			new.overflow = 0;
+			prev.val = __cdsg(&te->header.val, old.val, new.val);
+		} while (prev.val != old.val);
+
+		/* 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;
+	}
+
+	/* Account sample overflows in the event hardware structure */
+	if (sampl_overflow)
+		OVERFLOW_REG(hwc) = DIV_ROUND_UP(OVERFLOW_REG(hwc) +
+						 sampl_overflow, 1 + num_sdb);
+
+	/* Perf_event_overflow() and perf_event_account_interrupt() limit
+	 * the interrupt rate to an upper limit. Roughly 1000 samples per
+	 * task tick.
+	 * Hitting this limit results in a large number
+	 * of throttled REF_REPORT_THROTTLE entries and the samples
+	 * are dropped.
+	 * Slightly increase the interval to avoid hitting this limit.
+	 */
+	if (event_overflow) {
+		SAMPL_RATE(hwc) += DIV_ROUND_UP(SAMPL_RATE(hwc), 10);
+		debug_sprintf_event(sfdbg, 1, "%s: rate adjustment %ld\n",
+				    __func__,
+				    DIV_ROUND_UP(SAMPL_RATE(hwc), 10));
+	}
+
+	if (sampl_overflow || event_overflow)
+		debug_sprintf_event(sfdbg, 4, "%s: "
+				    "overflows: sample %llu event %llu"
+				    " total %llu num_sdb %llu\n",
+				    __func__, sampl_overflow, event_overflow,
+				    OVERFLOW_REG(hwc), num_sdb);
+}
+
+#define AUX_SDB_INDEX(aux, i) ((i) % aux->sfb.num_sdb)
+#define AUX_SDB_NUM(aux, start, end) (end >= start ? end - start + 1 : 0)
+#define AUX_SDB_NUM_ALERT(aux) AUX_SDB_NUM(aux, aux->head, aux->alert_mark)
+#define AUX_SDB_NUM_EMPTY(aux) AUX_SDB_NUM(aux, aux->head, aux->empty_mark)
+
+/*
+ * Get trailer entry by index of SDB.
+ */
+static struct hws_trailer_entry *aux_sdb_trailer(struct aux_buffer *aux,
+						 unsigned long index)
+{
+	unsigned long sdb;
+
+	index = AUX_SDB_INDEX(aux, index);
+	sdb = aux->sdb_index[index];
+	return (struct hws_trailer_entry *)trailer_entry_ptr(sdb);
+}
+
+/*
+ * Finish sampling on the cpu. Called by cpumsf_pmu_del() with pmu
+ * disabled. Collect the full SDBs in AUX buffer which have not reached
+ * the point of alert indicator. And ignore the SDBs which are not
+ * full.
+ *
+ * 1. Scan SDBs to see how much data is there and consume them.
+ * 2. Remove alert indicator in the buffer.
+ */
+static void aux_output_end(struct perf_output_handle *handle)
+{
+	unsigned long i, range_scan, idx;
+	struct aux_buffer *aux;
+	struct hws_trailer_entry *te;
+
+	aux = perf_get_aux(handle);
+	if (!aux)
+		return;
+
+	range_scan = AUX_SDB_NUM_ALERT(aux);
+	for (i = 0, idx = aux->head; i < range_scan; i++, idx++) {
+		te = aux_sdb_trailer(aux, idx);
+		if (!te->header.f)
+			break;
+	}
+	/* i is num of SDBs which are full */
+	perf_aux_output_end(handle, i << PAGE_SHIFT);
+
+	/* Remove alert indicators in the buffer */
+	te = aux_sdb_trailer(aux, aux->alert_mark);
+	te->header.a = 0;
+
+	debug_sprintf_event(sfdbg, 6, "%s: SDBs %ld range %ld head %ld\n",
+			    __func__, i, range_scan, aux->head);
+}
+
+/*
+ * Start sampling on the CPU. Called by cpumsf_pmu_add() when an event
+ * is first added to the CPU or rescheduled again to the CPU. It is called
+ * with pmu disabled.
+ *
+ * 1. Reset the trailer of SDBs to get ready for new data.
+ * 2. Tell the hardware where to put the data by reset the SDBs buffer
+ *    head(tear/dear).
+ */
+static int aux_output_begin(struct perf_output_handle *handle,
+			    struct aux_buffer *aux,
+			    struct cpu_hw_sf *cpuhw)
+{
+	unsigned long range;
+	unsigned long i, range_scan, idx;
+	unsigned long head, base, offset;
+	struct hws_trailer_entry *te;
+
+	if (WARN_ON_ONCE(handle->head & ~PAGE_MASK))
+		return -EINVAL;
+
+	aux->head = handle->head >> PAGE_SHIFT;
+	range = (handle->size + 1) >> PAGE_SHIFT;
+	if (range <= 1)
+		return -ENOMEM;
+
+	/*
+	 * SDBs between aux->head and aux->empty_mark are already ready
+	 * for new data. range_scan is num of SDBs not within them.
+	 */
+	debug_sprintf_event(sfdbg, 6,
+			    "%s: range %ld head %ld alert %ld empty %ld\n",
+			    __func__, range, aux->head, aux->alert_mark,
+			    aux->empty_mark);
+	if (range > AUX_SDB_NUM_EMPTY(aux)) {
+		range_scan = range - AUX_SDB_NUM_EMPTY(aux);
+		idx = aux->empty_mark + 1;
+		for (i = 0; i < range_scan; i++, idx++) {
+			te = aux_sdb_trailer(aux, idx);
+			te->header.f = 0;
+			te->header.a = 0;
+			te->header.overflow = 0;
+		}
+		/* Save the position of empty SDBs */
+		aux->empty_mark = aux->head + range - 1;
+	}
+
+	/* Set alert indicator */
+	aux->alert_mark = aux->head + range/2 - 1;
+	te = aux_sdb_trailer(aux, aux->alert_mark);
+	te->header.a = 1;
+
+	/* Reset hardware buffer head */
+	head = AUX_SDB_INDEX(aux, aux->head);
+	base = aux->sdbt_index[head / CPUM_SF_SDB_PER_TABLE];
+	offset = head % CPUM_SF_SDB_PER_TABLE;
+	cpuhw->lsctl.tear = base + offset * sizeof(unsigned long);
+	cpuhw->lsctl.dear = aux->sdb_index[head];
+
+	debug_sprintf_event(sfdbg, 6, "%s: head %ld alert %ld empty %ld "
+			    "index %ld tear %#lx dear %#lx\n", __func__,
+			    aux->head, aux->alert_mark, aux->empty_mark,
+			    head / CPUM_SF_SDB_PER_TABLE,
+			    cpuhw->lsctl.tear, cpuhw->lsctl.dear);
+
+	return 0;
+}
+
+/*
+ * Set alert indicator on SDB at index @alert_index while sampler is running.
+ *
+ * Return true if successfully.
+ * Return false if full indicator is already set by hardware sampler.
+ */
+static bool aux_set_alert(struct aux_buffer *aux, unsigned long alert_index,
+			  unsigned long long *overflow)
+{
+	union hws_trailer_header old, prev, new;
+	struct hws_trailer_entry *te;
+
+	te = aux_sdb_trailer(aux, alert_index);
+	/* READ_ONCE() 16 byte header */
+	prev.val = __cdsg(&te->header.val, 0, 0);
+	do {
+		old.val = prev.val;
+		new.val = prev.val;
+		*overflow = old.overflow;
+		if (old.f) {
+			/*
+			 * SDB is already set by hardware.
+			 * Abort and try to set somewhere
+			 * behind.
+			 */
+			return false;
+		}
+		new.a = 1;
+		new.overflow = 0;
+		prev.val = __cdsg(&te->header.val, old.val, new.val);
+	} while (prev.val != old.val);
+	return true;
+}
+
+/*
+ * aux_reset_buffer() - Scan and setup SDBs for new samples
+ * @aux:	The AUX buffer to set
+ * @range:	The range of SDBs to scan started from aux->head
+ * @overflow:	Set to overflow count
+ *
+ * Set alert indicator on the SDB at index of aux->alert_mark. If this SDB is
+ * marked as empty, check if it is already set full by the hardware sampler.
+ * If yes, that means new data is already there before we can set an alert
+ * indicator. Caller should try to set alert indicator to some position behind.
+ *
+ * Scan the SDBs in AUX buffer from behind aux->empty_mark. They are used
+ * previously and have already been consumed by user space. Reset these SDBs
+ * (clear full indicator and alert indicator) for new data.
+ * If aux->alert_mark fall in this area, just set it. Overflow count is
+ * recorded while scanning.
+ *
+ * SDBs between aux->head and aux->empty_mark are already reset at last time.
+ * and ready for new samples. So scanning on this area could be skipped.
+ *
+ * Return true if alert indicator is set successfully and false if not.
+ */
+static bool aux_reset_buffer(struct aux_buffer *aux, unsigned long range,
+			     unsigned long long *overflow)
+{
+	unsigned long i, range_scan, idx, idx_old;
+	union hws_trailer_header old, prev, new;
+	unsigned long long orig_overflow;
+	struct hws_trailer_entry *te;
+
+	debug_sprintf_event(sfdbg, 6, "%s: range %ld head %ld alert %ld "
+			    "empty %ld\n", __func__, range, aux->head,
+			    aux->alert_mark, aux->empty_mark);
+	if (range <= AUX_SDB_NUM_EMPTY(aux))
+		/*
+		 * No need to scan. All SDBs in range are marked as empty.
+		 * Just set alert indicator. Should check race with hardware
+		 * sampler.
+		 */
+		return aux_set_alert(aux, aux->alert_mark, overflow);
+
+	if (aux->alert_mark <= aux->empty_mark)
+		/*
+		 * Set alert indicator on empty SDB. Should check race
+		 * with hardware sampler.
+		 */
+		if (!aux_set_alert(aux, aux->alert_mark, overflow))
+			return false;
+
+	/*
+	 * Scan the SDBs to clear full and alert indicator used previously.
+	 * Start scanning from one SDB behind empty_mark. If the new alert
+	 * indicator fall into this range, set it.
+	 */
+	range_scan = range - AUX_SDB_NUM_EMPTY(aux);
+	idx_old = idx = aux->empty_mark + 1;
+	for (i = 0; i < range_scan; i++, idx++) {
+		te = aux_sdb_trailer(aux, idx);
+		/* READ_ONCE() 16 byte header */
+		prev.val = __cdsg(&te->header.val, 0, 0);
+		do {
+			old.val = prev.val;
+			new.val = prev.val;
+			orig_overflow = old.overflow;
+			new.f = 0;
+			new.overflow = 0;
+			if (idx == aux->alert_mark)
+				new.a = 1;
+			else
+				new.a = 0;
+			prev.val = __cdsg(&te->header.val, old.val, new.val);
+		} while (prev.val != old.val);
+		*overflow += orig_overflow;
+	}
+
+	/* Update empty_mark to new position */
+	aux->empty_mark = aux->head + range - 1;
+
+	debug_sprintf_event(sfdbg, 6, "%s: range_scan %ld idx %ld..%ld "
+			    "empty %ld\n", __func__, range_scan, idx_old,
+			    idx - 1, aux->empty_mark);
+	return true;
+}
+
+/*
+ * Measurement alert handler for diagnostic mode sampling.
+ */
+static void hw_collect_aux(struct cpu_hw_sf *cpuhw)
+{
+	struct aux_buffer *aux;
+	int done = 0;
+	unsigned long range = 0, size;
+	unsigned long long overflow = 0;
+	struct perf_output_handle *handle = &cpuhw->handle;
+	unsigned long num_sdb;
+
+	aux = perf_get_aux(handle);
+	if (WARN_ON_ONCE(!aux))
+		return;
+
+	/* Inform user space new data arrived */
+	size = AUX_SDB_NUM_ALERT(aux) << PAGE_SHIFT;
+	debug_sprintf_event(sfdbg, 6, "%s: #alert %ld\n", __func__,
+			    size >> PAGE_SHIFT);
+	perf_aux_output_end(handle, size);
+
+	num_sdb = aux->sfb.num_sdb;
+	while (!done) {
+		/* Get an output handle */
+		aux = perf_aux_output_begin(handle, cpuhw->event);
+		if (handle->size == 0) {
+			pr_err("The AUX buffer with %lu pages for the "
+			       "diagnostic-sampling mode is full\n",
+				num_sdb);
+			debug_sprintf_event(sfdbg, 1,
+					    "%s: AUX buffer used up\n",
+					    __func__);
+			break;
+		}
+		if (WARN_ON_ONCE(!aux))
+			return;
+
+		/* Update head and alert_mark to new position */
+		aux->head = handle->head >> PAGE_SHIFT;
+		range = (handle->size + 1) >> PAGE_SHIFT;
+		if (range == 1)
+			aux->alert_mark = aux->head;
+		else
+			aux->alert_mark = aux->head + range/2 - 1;
+
+		if (aux_reset_buffer(aux, range, &overflow)) {
+			if (!overflow) {
+				done = 1;
+				break;
+			}
+			size = range << PAGE_SHIFT;
+			perf_aux_output_end(&cpuhw->handle, size);
+			pr_err("Sample data caused the AUX buffer with %lu "
+			       "pages to overflow\n", aux->sfb.num_sdb);
+			debug_sprintf_event(sfdbg, 1, "%s: head %ld range %ld "
+					    "overflow %lld\n", __func__,
+					    aux->head, range, overflow);
+		} else {
+			size = AUX_SDB_NUM_ALERT(aux) << PAGE_SHIFT;
+			perf_aux_output_end(&cpuhw->handle, size);
+			debug_sprintf_event(sfdbg, 6, "%s: head %ld alert %ld "
+					    "already full, try another\n",
+					    __func__,
+					    aux->head, aux->alert_mark);
+		}
+	}
+
+	if (done)
+		debug_sprintf_event(sfdbg, 6, "%s: head %ld alert %ld "
+				    "empty %ld\n", __func__, aux->head,
+				    aux->alert_mark, aux->empty_mark);
+}
+
+/*
+ * Callback when freeing AUX buffers.
+ */
+static void aux_buffer_free(void *data)
+{
+	struct aux_buffer *aux = data;
+	unsigned long i, num_sdbt;
+
+	if (!aux)
+		return;
+
+	/* Free SDBT. SDB is freed by the caller */
+	num_sdbt = aux->sfb.num_sdbt;
+	for (i = 0; i < num_sdbt; i++)
+		free_page(aux->sdbt_index[i]);
+
+	kfree(aux->sdbt_index);
+	kfree(aux->sdb_index);
+	kfree(aux);
+
+	debug_sprintf_event(sfdbg, 4, "%s: SDBTs %lu\n", __func__, num_sdbt);
+}
+
+static void aux_sdb_init(unsigned long sdb)
+{
+	struct hws_trailer_entry *te;
+
+	te = (struct hws_trailer_entry *)trailer_entry_ptr(sdb);
+
+	/* Save clock base */
+	te->clock_base = 1;
+	te->progusage2 = tod_clock_base.tod;
+}
+
+/*
+ * aux_buffer_setup() - Setup AUX buffer for diagnostic mode sampling
+ * @event:	Event the buffer is setup for, event->cpu == -1 means current
+ * @pages:	Array of pointers to buffer pages passed from perf core
+ * @nr_pages:	Total pages
+ * @snapshot:	Flag for snapshot mode
+ *
+ * This is the callback when setup an event using AUX buffer. Perf tool can
+ * trigger this by an additional mmap() call on the event. Unlike the buffer
+ * for basic samples, AUX buffer belongs to the event. It is scheduled with
+ * the task among online cpus when it is a per-thread event.
+ *
+ * Return the private AUX buffer structure if success or NULL if fails.
+ */
+static void *aux_buffer_setup(struct perf_event *event, void **pages,
+			      int nr_pages, bool snapshot)
+{
+	struct sf_buffer *sfb;
+	struct aux_buffer *aux;
+	unsigned long *new, *tail;
+	int i, n_sdbt;
+
+	if (!nr_pages || !pages)
+		return NULL;
+
+	if (nr_pages > CPUM_SF_MAX_SDB * CPUM_SF_SDB_DIAG_FACTOR) {
+		pr_err("AUX buffer size (%i pages) is larger than the "
+		       "maximum sampling buffer limit\n",
+		       nr_pages);
+		return NULL;
+	} else if (nr_pages < CPUM_SF_MIN_SDB * CPUM_SF_SDB_DIAG_FACTOR) {
+		pr_err("AUX buffer size (%i pages) is less than the "
+		       "minimum sampling buffer limit\n",
+		       nr_pages);
+		return NULL;
+	}
+
+	/* Allocate aux_buffer struct for the event */
+	aux = kzalloc(sizeof(struct aux_buffer), GFP_KERNEL);
+	if (!aux)
+		goto no_aux;
+	sfb = &aux->sfb;
+
+	/* Allocate sdbt_index for fast reference */
+	n_sdbt = DIV_ROUND_UP(nr_pages, CPUM_SF_SDB_PER_TABLE);
+	aux->sdbt_index = kmalloc_array(n_sdbt, sizeof(void *), GFP_KERNEL);
+	if (!aux->sdbt_index)
+		goto no_sdbt_index;
+
+	/* Allocate sdb_index for fast reference */
+	aux->sdb_index = kmalloc_array(nr_pages, sizeof(void *), GFP_KERNEL);
+	if (!aux->sdb_index)
+		goto no_sdb_index;
+
+	/* Allocate the first SDBT */
+	sfb->num_sdbt = 0;
+	sfb->sdbt = (unsigned long *) get_zeroed_page(GFP_KERNEL);
+	if (!sfb->sdbt)
+		goto no_sdbt;
+	aux->sdbt_index[sfb->num_sdbt++] = (unsigned long)sfb->sdbt;
+	tail = sfb->tail = sfb->sdbt;
+
+	/*
+	 * Link the provided pages of AUX buffer to SDBT.
+	 * Allocate SDBT if needed.
+	 */
+	for (i = 0; i < nr_pages; i++, tail++) {
+		if (require_table_link(tail)) {
+			new = (unsigned long *) get_zeroed_page(GFP_KERNEL);
+			if (!new)
+				goto no_sdbt;
+			aux->sdbt_index[sfb->num_sdbt++] = (unsigned long)new;
+			/* Link current page to tail of chain */
+			*tail = (unsigned long)(void *) new + 1;
+			tail = new;
+		}
+		/* Tail is the entry in a SDBT */
+		*tail = (unsigned long)pages[i];
+		aux->sdb_index[i] = (unsigned long)pages[i];
+		aux_sdb_init((unsigned long)pages[i]);
+	}
+	sfb->num_sdb = nr_pages;
+
+	/* Link the last entry in the SDBT to the first SDBT */
+	*tail = (unsigned long) sfb->sdbt + 1;
+	sfb->tail = tail;
+
+	/*
+	 * Initial all SDBs are zeroed. Mark it as empty.
+	 * So there is no need to clear the full indicator
+	 * when this event is first added.
+	 */
+	aux->empty_mark = sfb->num_sdb - 1;
+
+	debug_sprintf_event(sfdbg, 4, "%s: SDBTs %lu SDBs %lu\n", __func__,
+			    sfb->num_sdbt, sfb->num_sdb);
+
+	return aux;
+
+no_sdbt:
+	/* SDBs (AUX buffer pages) are freed by caller */
+	for (i = 0; i < sfb->num_sdbt; i++)
+		free_page(aux->sdbt_index[i]);
+	kfree(aux->sdb_index);
+no_sdb_index:
+	kfree(aux->sdbt_index);
+no_sdbt_index:
+	kfree(aux);
+no_aux:
+	return NULL;
+}
+
+static void cpumsf_pmu_read(struct perf_event *event)
+{
+	/* Nothing to do ... updates are interrupt-driven */
+}
+
+/* Check if the new sampling period/freqeuncy is appropriate.
+ *
+ * Return non-zero on error and zero on passed checks.
+ */
+static int cpumsf_pmu_check_period(struct perf_event *event, u64 value)
+{
+	struct hws_qsi_info_block si;
+	unsigned long rate;
+	bool do_freq;
+
+	memset(&si, 0, sizeof(si));
+	if (event->cpu == -1) {
+		if (qsi(&si))
+			return -ENODEV;
+	} else {
+		/* Event is pinned to a particular CPU, retrieve the per-CPU
+		 * sampling structure for accessing the CPU-specific QSI.
+		 */
+		struct cpu_hw_sf *cpuhw = &per_cpu(cpu_hw_sf, event->cpu);
+
+		si = cpuhw->qsi;
+	}
+
+	do_freq = !!SAMPLE_FREQ_MODE(&event->hw);
+	rate = getrate(do_freq, value, &si);
+	if (!rate)
+		return -EINVAL;
+
+	event->attr.sample_period = rate;
+	SAMPL_RATE(&event->hw) = rate;
+	hw_init_period(&event->hw, SAMPL_RATE(&event->hw));
+	debug_sprintf_event(sfdbg, 4, "%s:"
+			    " cpu %d value %#llx period %#llx freq %d\n",
+			    __func__, event->cpu, value,
+			    event->attr.sample_period, do_freq);
+	return 0;
+}
+
+/* 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 = this_cpu_ptr(&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;
+	if (SAMPL_DIAG_MODE(&event->hw))
+		cpuhw->lsctl.cd = 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 = this_cpu_ptr(&cpu_hw_sf);
+
+	if (event->hw.state & PERF_HES_STOPPED)
+		return;
+
+	perf_pmu_disable(event->pmu);
+	cpuhw->lsctl.cs = 0;
+	cpuhw->lsctl.cd = 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 = this_cpu_ptr(&cpu_hw_sf);
+	struct aux_buffer *aux;
+	int err;
+
+	if (cpuhw->flags & PMU_F_IN_USE)
+		return -EAGAIN;
+
+	if (!SAMPL_DIAG_MODE(&event->hw) && !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.interval = SAMPL_RATE(&event->hw);
+	if (!SAMPL_DIAG_MODE(&event->hw)) {
+		cpuhw->lsctl.tear = (unsigned long) cpuhw->sfb.sdbt;
+		cpuhw->lsctl.dear = *(unsigned long *) cpuhw->sfb.sdbt;
+		TEAR_REG(&event->hw) = (unsigned long) 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 || cpuhw->lsctl.ed == 1)) {
+		err = -EAGAIN;
+		goto out;
+	}
+	if (SAMPL_DIAG_MODE(&event->hw)) {
+		aux = perf_aux_output_begin(&cpuhw->handle, event);
+		if (!aux) {
+			err = -EINVAL;
+			goto out;
+		}
+		err = aux_output_begin(&cpuhw->handle, aux, cpuhw);
+		if (err)
+			goto out;
+		cpuhw->lsctl.ed = 1;
+	}
+	cpuhw->lsctl.es = 1;
+
+	/* Set in_use flag and store event */
+	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 = this_cpu_ptr(&cpu_hw_sf);
+
+	perf_pmu_disable(event->pmu);
+	cpumsf_pmu_stop(event, PERF_EF_UPDATE);
+
+	cpuhw->lsctl.es = 0;
+	cpuhw->lsctl.ed = 0;
+	cpuhw->flags &= ~PMU_F_IN_USE;
+	cpuhw->event = NULL;
+
+	if (SAMPL_DIAG_MODE(&event->hw))
+		aux_output_end(&cpuhw->handle);
+	perf_event_update_userpage(event);
+	perf_pmu_enable(event->pmu);
+}
+
+CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC, PERF_EVENT_CPUM_SF);
+CPUMF_EVENT_ATTR(SF, SF_CYCLES_BASIC_DIAG, PERF_EVENT_CPUM_SF_DIAG);
+
+/* Attribute list for CPU_SF.
+ *
+ * The availablitiy depends on the CPU_MF sampling facility authorization
+ * for basic + diagnositic samples. This is determined at initialization
+ * time by the sampling facility device driver.
+ * If the authorization for basic samples is turned off, it should be
+ * also turned off for diagnostic sampling.
+ *
+ * During initialization of the device driver, check the authorization
+ * level for diagnostic sampling and installs the attribute
+ * file for diagnostic sampling if necessary.
+ *
+ * For now install a placeholder to reference all possible attributes:
+ * SF_CYCLES_BASIC and SF_CYCLES_BASIC_DIAG.
+ * Add another entry for the final NULL pointer.
+ */
+enum {
+	SF_CYCLES_BASIC_ATTR_IDX = 0,
+	SF_CYCLES_BASIC_DIAG_ATTR_IDX,
+	SF_CYCLES_ATTR_MAX
+};
+
+static struct attribute *cpumsf_pmu_events_attr[SF_CYCLES_ATTR_MAX + 1] = {
+	[SF_CYCLES_BASIC_ATTR_IDX] = CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC)
+};
+
+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,
+
+	.attr_groups  = cpumsf_pmu_attr_groups,
+
+	.setup_aux    = aux_buffer_setup,
+	.free_aux     = aux_buffer_free,
+
+	.check_period = cpumsf_pmu_check_period,
+};
+
+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 = this_cpu_ptr(&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)
+			if (SAMPL_DIAG_MODE(&cpuhw->event->hw))
+				hw_collect_aux(cpuhw);
+			else
+				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, "%s: alert %#x\n", __func__,
+				    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 cpusf_pmu_setup(unsigned int cpu, int flags)
+{
+	/* Ignore the notification if no events are scheduled on the PMU.
+	 * This might be racy...
+	 */
+	if (!atomic_read(&num_events))
+		return 0;
+
+	local_irq_disable();
+	setup_pmc_cpu(&flags);
+	local_irq_enable();
+	return 0;
+}
+
+static int s390_pmu_sf_online_cpu(unsigned int cpu)
+{
+	return cpusf_pmu_setup(cpu, PMC_INIT);
+}
+
+static int s390_pmu_sf_offline_cpu(unsigned int cpu)
+{
+	return cpusf_pmu_setup(cpu, PMC_RELEASE);
+}
+
+static int param_get_sfb_size(char *buffer, const struct kernel_param *kp)
+{
+	if (!cpum_sf_avail())
+		return -ENODEV;
+	return sprintf(buffer, "%lu,%lu", CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB);
+}
+
+static int param_set_sfb_size(const char *val, const struct kernel_param *kp)
+{
+	int rc;
+	unsigned long min, max;
+
+	if (!cpum_sf_avail())
+		return -ENODEV;
+	if (!val || !strlen(val))
+		return -EINVAL;
+
+	/* Valid parameter values: "min,max" or "max" */
+	min = CPUM_SF_MIN_SDB;
+	max = CPUM_SF_MAX_SDB;
+	if (strchr(val, ','))
+		rc = (sscanf(val, "%lu,%lu", &min, &max) == 2) ? 0 : -EINVAL;
+	else
+		rc = kstrtoul(val, 10, &max);
+
+	if (min < 2 || min >= max || max > get_num_physpages())
+		rc = -EINVAL;
+	if (rc)
+		return rc;
+
+	sfb_set_limits(min, max);
+	pr_info("The sampling buffer limits have changed to: "
+		"min %lu max %lu (diag %lu)\n",
+		CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB, CPUM_SF_SDB_DIAG_FACTOR);
+	return 0;
+}
+
+#define param_check_sfb_size(name, p) __param_check(name, p, void)
+static const struct kernel_param_ops param_ops_sfb_size = {
+	.set = param_set_sfb_size,
+	.get = param_get_sfb_size,
+};
+
+#define RS_INIT_FAILURE_QSI	  0x0001
+#define RS_INIT_FAILURE_BSDES	  0x0002
+#define RS_INIT_FAILURE_ALRT	  0x0003
+#define RS_INIT_FAILURE_PERF	  0x0004
+static void __init pr_cpumsf_err(unsigned int reason)
+{
+	pr_err("Sampling facility support for perf is not available: "
+	       "reason %#x\n", reason);
+}
+
+static int __init init_cpum_sampling_pmu(void)
+{
+	struct hws_qsi_info_block si;
+	int err;
+
+	if (!cpum_sf_avail())
+		return -ENODEV;
+
+	memset(&si, 0, sizeof(si));
+	if (qsi(&si)) {
+		pr_cpumsf_err(RS_INIT_FAILURE_QSI);
+		return -ENODEV;
+	}
+
+	if (!si.as && !si.ad)
+		return -ENODEV;
+
+	if (si.bsdes != sizeof(struct hws_basic_entry)) {
+		pr_cpumsf_err(RS_INIT_FAILURE_BSDES);
+		return -EINVAL;
+	}
+
+	if (si.ad) {
+		sfb_set_limits(CPUM_SF_MIN_SDB, CPUM_SF_MAX_SDB);
+		/* Sampling of diagnostic data authorized,
+		 * install event into attribute list of PMU device.
+		 */
+		cpumsf_pmu_events_attr[SF_CYCLES_BASIC_DIAG_ATTR_IDX] =
+			CPUMF_EVENT_PTR(SF, SF_CYCLES_BASIC_DIAG);
+	}
+
+	sfdbg = debug_register(KMSG_COMPONENT, 2, 1, 80);
+	if (!sfdbg) {
+		pr_err("Registering for s390dbf failed\n");
+		return -ENOMEM;
+	}
+	debug_register_view(sfdbg, &debug_sprintf_view);
+
+	err = register_external_irq(EXT_IRQ_MEASURE_ALERT,
+				    cpumf_measurement_alert);
+	if (err) {
+		pr_cpumsf_err(RS_INIT_FAILURE_ALRT);
+		debug_unregister(sfdbg);
+		goto out;
+	}
+
+	err = perf_pmu_register(&cpumf_sampling, "cpum_sf", PERF_TYPE_RAW);
+	if (err) {
+		pr_cpumsf_err(RS_INIT_FAILURE_PERF);
+		unregister_external_irq(EXT_IRQ_MEASURE_ALERT,
+					cpumf_measurement_alert);
+		debug_unregister(sfdbg);
+		goto out;
+	}
+
+	cpuhp_setup_state(CPUHP_AP_PERF_S390_SF_ONLINE, "perf/s390/sf:online",
+			  s390_pmu_sf_online_cpu, s390_pmu_sf_offline_cpu);
+out:
+	return err;
+}
+
+arch_initcall(init_cpum_sampling_pmu);
+core_param(cpum_sfb_size, CPUM_SF_MAX_SDB, sfb_size, 0644);