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;
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);
sampl_overflow, event_overflow);
}
+#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->flags & SDB_TE_BUFFER_FULL_MASK))
+ 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->flags &= ~SDB_TE_ALERT_REQ_MASK;
+
+ debug_sprintf_event(sfdbg, 6, "aux_output_end: collect %lx SDBs\n", i);
+}
+
+/*
+ * 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.
+ */
+ 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->flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
+ te->flags = te->flags & ~SDB_TE_ALERT_REQ_MASK;
+ te->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->flags = te->flags | SDB_TE_ALERT_REQ_MASK;
+
+ /* 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, "aux_output_begin: "
+ "head->alert_mark->empty_mark (num_alert, range)"
+ "[%lx -> %lx -> %lx] (%lx, %lx) "
+ "tear index %lx, tear %lx dear %lx\n",
+ aux->head, aux->alert_mark, aux->empty_mark,
+ AUX_SDB_NUM_ALERT(aux), range,
+ 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)
+{
+ unsigned long long orig_overflow, orig_flags, new_flags;
+ struct hws_trailer_entry *te;
+
+ te = aux_sdb_trailer(aux, alert_index);
+ do {
+ orig_flags = te->flags;
+ orig_overflow = te->overflow;
+ *overflow = orig_overflow;
+ if (orig_flags & SDB_TE_BUFFER_FULL_MASK) {
+ /*
+ * SDB is already set by hardware.
+ * Abort and try to set somewhere
+ * behind.
+ */
+ return false;
+ }
+ new_flags = orig_flags | SDB_TE_ALERT_REQ_MASK;
+ } while (!cmpxchg_double(&te->flags, &te->overflow,
+ orig_flags, orig_overflow,
+ new_flags, 0ULL));
+ 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 long orig_overflow, orig_flags, new_flags;
+ unsigned long i, range_scan, idx;
+ struct hws_trailer_entry *te;
+
+ 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 = aux->empty_mark + 1;
+ for (i = 0; i < range_scan; i++, idx++) {
+ te = aux_sdb_trailer(aux, idx);
+ do {
+ orig_flags = te->flags;
+ orig_overflow = te->overflow;
+ new_flags = orig_flags & ~SDB_TE_BUFFER_FULL_MASK;
+ if (idx == aux->alert_mark)
+ new_flags |= SDB_TE_ALERT_REQ_MASK;
+ else
+ new_flags &= ~SDB_TE_ALERT_REQ_MASK;
+ } while (!cmpxchg_double(&te->flags, &te->overflow,
+ orig_flags, orig_overflow,
+ new_flags, 0ULL));
+ *overflow += orig_overflow;
+ }
+
+ /* Update empty_mark to new position */
+ aux->empty_mark = aux->head + range - 1;
+
+ 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;
+ 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, "AUX buffer used up\n");
+ 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", num_sdb);
+ debug_sprintf_event(sfdbg, 1, "head %lx range %lx "
+ "overflow %llx\n",
+ 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, "head %lx alert %lx "
+ "already full, try another\n",
+ aux->head, aux->alert_mark);
+ }
+ }
+
+ if (done)
+ debug_sprintf_event(sfdbg, 6, "aux_reset_buffer: "
+ "[%lx -> %lx -> %lx] (%lx, %lx)\n",
+ aux->head, aux->alert_mark, aux->empty_mark,
+ AUX_SDB_NUM_ALERT(aux), range);
+}
+
+/*
+ * 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, "aux_buffer_free: free "
+ "%lu SDBTs\n", num_sdbt);
+}
+
+/*
+ * aux_buffer_setup() - Setup AUX buffer for diagnostic mode sampling
+ * @cpu: On which to allocate, -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(int cpu, 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 = kmalloc(sizeof(struct aux_buffer), GFP_KERNEL);
+ if (!aux)
+ goto no_aux;
+ sfb = &aux->sfb;
+
+ /* Allocate sdbt_index for fast reference */
+ n_sdbt = (nr_pages + CPUM_SF_SDB_PER_TABLE - 1) / 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];
+ }
+ 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, "aux_buffer_setup: setup %lu SDBTs"
+ " and %lu SDBs\n",
+ 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 */
.read = cpumsf_pmu_read,
.attr_groups = cpumsf_pmu_attr_groups,
+
+ .setup_aux = aux_buffer_setup,
+ .free_aux = aux_buffer_free,
};
static void cpumf_measurement_alert(struct ext_code ext_code,
projects / users / hch / xfs.git / commitdiff