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perf_cpum_sf.c
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perf_cpum_sf.c
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// 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)
{
unsigned long sdb, *trailer;
/* Allocate and initialize sample-data-block */
sdb = get_zeroed_page(gfp_flags);
if (!sdb)
return -ENOMEM;
trailer = trailer_entry_ptr(sdb);
*trailer = SDB_TE_ALERT_REQ_MASK;
/* 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, 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)