diff options
| -rw-r--r-- | arch/s390/kernel/perf_cpum_sf.c | 446 |
1 files changed, 446 insertions, 0 deletions
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c index bd4bbf61aaf3..51dbd8d90dbe 100644 --- a/arch/s390/kernel/perf_cpum_sf.c +++ b/arch/s390/kernel/perf_cpum_sf.c @@ -77,6 +77,15 @@ struct sf_buffer { 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; @@ -85,6 +94,7 @@ struct cpu_hw_sf { 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); @@ -1291,6 +1301,439 @@ static void hw_perf_event_update(struct perf_event *event, int flush_all) 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 */ @@ -1448,6 +1891,9 @@ static struct pmu cpumf_sampling = { .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, |