--- /dev/null
+/*
+ * BTS PMU driver for perf
+ * Copyright (c) 2013-2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#undef DEBUG
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitops.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/coredump.h>
+
+#include <asm-generic/sizes.h>
+#include <asm/perf_event.h>
+
+#include "perf_event.h"
+
+struct bts_ctx {
+ struct perf_output_handle handle;
+ struct debug_store ds_back;
+ int started;
+};
+
+static DEFINE_PER_CPU(struct bts_ctx, bts_ctx);
+
+#define BTS_RECORD_SIZE 24
+#define BTS_SAFETY_MARGIN 4080
+
+struct bts_phys {
+ struct page *page;
+ unsigned long size;
+ unsigned long offset;
+ unsigned long displacement;
+};
+
+struct bts_buffer {
+ size_t real_size; /* multiple of BTS_RECORD_SIZE */
+ unsigned int nr_pages;
+ unsigned int nr_bufs;
+ unsigned int cur_buf;
+ bool snapshot;
+ local_t data_size;
+ local_t lost;
+ local_t head;
+ unsigned long end;
+ void **data_pages;
+ struct bts_phys buf[0];
+};
+
+struct pmu bts_pmu;
+
+void intel_pmu_enable_bts(u64 config);
+void intel_pmu_disable_bts(void);
+
+static size_t buf_size(struct page *page)
+{
+ return 1 << (PAGE_SHIFT + page_private(page));
+}
+
+static void *
+bts_buffer_setup_aux(int cpu, void **pages, int nr_pages, bool overwrite)
+{
+ struct bts_buffer *buf;
+ struct page *page;
+ int node = (cpu == -1) ? cpu : cpu_to_node(cpu);
+ unsigned long offset;
+ size_t size = nr_pages << PAGE_SHIFT;
+ int pg, nbuf, pad;
+
+ /* count all the high order buffers */
+ for (pg = 0, nbuf = 0; pg < nr_pages;) {
+ page = virt_to_page(pages[pg]);
+ if (WARN_ON_ONCE(!PagePrivate(page) && nr_pages > 1))
+ return NULL;
+ pg += 1 << page_private(page);
+ nbuf++;
+ }
+
+ /*
+ * to avoid interrupts in overwrite mode, only allow one physical
+ */
+ if (overwrite && nbuf > 1)
+ return NULL;
+
+ buf = kzalloc_node(offsetof(struct bts_buffer, buf[nbuf]), GFP_KERNEL, node);
+ if (!buf)
+ return NULL;
+
+ buf->nr_pages = nr_pages;
+ buf->nr_bufs = nbuf;
+ buf->snapshot = overwrite;
+ buf->data_pages = pages;
+ buf->real_size = size - size % BTS_RECORD_SIZE;
+
+ for (pg = 0, nbuf = 0, offset = 0, pad = 0; nbuf < buf->nr_bufs; nbuf++) {
+ unsigned int __nr_pages;
+
+ page = virt_to_page(pages[pg]);
+ __nr_pages = PagePrivate(page) ? 1 << page_private(page) : 1;
+ buf->buf[nbuf].page = page;
+ buf->buf[nbuf].offset = offset;
+ buf->buf[nbuf].displacement = (pad ? BTS_RECORD_SIZE - pad : 0);
+ buf->buf[nbuf].size = buf_size(page) - buf->buf[nbuf].displacement;
+ pad = buf->buf[nbuf].size % BTS_RECORD_SIZE;
+ buf->buf[nbuf].size -= pad;
+
+ pg += __nr_pages;
+ offset += __nr_pages << PAGE_SHIFT;
+ }
+
+ return buf;
+}
+
+static void bts_buffer_free_aux(void *data)
+{
+ kfree(data);
+}
+
+static unsigned long bts_buffer_offset(struct bts_buffer *buf, unsigned int idx)
+{
+ return buf->buf[idx].offset + buf->buf[idx].displacement;
+}
+
+static void
+bts_config_buffer(struct bts_buffer *buf)
+{
+ int cpu = raw_smp_processor_id();
+ struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds;
+ struct bts_phys *phys = &buf->buf[buf->cur_buf];
+ unsigned long index, thresh = 0, end = phys->size;
+ struct page *page = phys->page;
+
+ index = local_read(&buf->head);
+
+ if (!buf->snapshot) {
+ if (buf->end < phys->offset + buf_size(page))
+ end = buf->end - phys->offset - phys->displacement;
+
+ index -= phys->offset + phys->displacement;
+
+ if (end - index > BTS_SAFETY_MARGIN)
+ thresh = end - BTS_SAFETY_MARGIN;
+ else if (end - index > BTS_RECORD_SIZE)
+ thresh = end - BTS_RECORD_SIZE;
+ else
+ thresh = end;
+ }
+
+ ds->bts_buffer_base = (u64)page_address(page) + phys->displacement;
+ ds->bts_index = ds->bts_buffer_base + index;
+ ds->bts_absolute_maximum = ds->bts_buffer_base + end;
+ ds->bts_interrupt_threshold = !buf->snapshot
+ ? ds->bts_buffer_base + thresh
+ : ds->bts_absolute_maximum + BTS_RECORD_SIZE;
+}
+
+static void bts_buffer_pad_out(struct bts_phys *phys, unsigned long head)
+{
+ unsigned long index = head - phys->offset;
+
+ memset(page_address(phys->page) + index, 0, phys->size - index);
+}
+
+static bool bts_buffer_is_full(struct bts_buffer *buf, struct bts_ctx *bts)
+{
+ if (buf->snapshot)
+ return false;
+
+ if (local_read(&buf->data_size) >= bts->handle.size ||
+ bts->handle.size - local_read(&buf->data_size) < BTS_RECORD_SIZE)
+ return true;
+
+ return false;
+}
+
+static void bts_update(struct bts_ctx *bts)
+{
+ int cpu = raw_smp_processor_id();
+ struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds;
+ struct bts_buffer *buf = perf_get_aux(&bts->handle);
+ unsigned long index = ds->bts_index - ds->bts_buffer_base, old, head;
+
+ if (!buf)
+ return;
+
+ head = index + bts_buffer_offset(buf, buf->cur_buf);
+ old = local_xchg(&buf->head, head);
+
+ if (!buf->snapshot) {
+ if (old == head)
+ return;
+
+ if (ds->bts_index >= ds->bts_absolute_maximum)
+ local_inc(&buf->lost);
+
+ /*
+ * old and head are always in the same physical buffer, so we
+ * can subtract them to get the data size.
+ */
+ local_add(head - old, &buf->data_size);
+ } else {
+ local_set(&buf->data_size, head);
+ }
+}
+
+static void __bts_event_start(struct perf_event *event)
+{
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+ struct bts_buffer *buf = perf_get_aux(&bts->handle);
+ u64 config = 0;
+
+ if (!buf || bts_buffer_is_full(buf, bts))
+ return;
+
+ event->hw.state = 0;
+
+ if (!buf->snapshot)
+ config |= ARCH_PERFMON_EVENTSEL_INT;
+ if (!event->attr.exclude_kernel)
+ config |= ARCH_PERFMON_EVENTSEL_OS;
+ if (!event->attr.exclude_user)
+ config |= ARCH_PERFMON_EVENTSEL_USR;
+
+ bts_config_buffer(buf);
+
+ /*
+ * local barrier to make sure that ds configuration made it
+ * before we enable BTS
+ */
+ wmb();
+
+ intel_pmu_enable_bts(config);
+}
+
+static void bts_event_start(struct perf_event *event, int flags)
+{
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+
+ __bts_event_start(event);
+
+ /* PMI handler: this counter is running and likely generating PMIs */
+ ACCESS_ONCE(bts->started) = 1;
+}
+
+static void __bts_event_stop(struct perf_event *event)
+{
+ /*
+ * No extra synchronization is mandated by the documentation to have
+ * BTS data stores globally visible.
+ */
+ intel_pmu_disable_bts();
+
+ if (event->hw.state & PERF_HES_STOPPED)
+ return;
+
+ ACCESS_ONCE(event->hw.state) |= PERF_HES_STOPPED;
+}
+
+static void bts_event_stop(struct perf_event *event, int flags)
+{
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+
+ /* PMI handler: don't restart this counter */
+ ACCESS_ONCE(bts->started) = 0;
+
+ __bts_event_stop(event);
+
+ if (flags & PERF_EF_UPDATE)
+ bts_update(bts);
+}
+
+void intel_bts_enable_local(void)
+{
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+
+ if (bts->handle.event && bts->started)
+ __bts_event_start(bts->handle.event);
+}
+
+void intel_bts_disable_local(void)
+{
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+
+ if (bts->handle.event)
+ __bts_event_stop(bts->handle.event);
+}
+
+static int
+bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
+{
+ unsigned long head, space, next_space, pad, gap, skip, wakeup;
+ unsigned int next_buf;
+ struct bts_phys *phys, *next_phys;
+ int ret;
+
+ if (buf->snapshot)
+ return 0;
+
+ head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
+ if (WARN_ON_ONCE(head != local_read(&buf->head)))
+ return -EINVAL;
+
+ phys = &buf->buf[buf->cur_buf];
+ space = phys->offset + phys->displacement + phys->size - head;
+ pad = space;
+ if (space > handle->size) {
+ space = handle->size;
+ space -= space % BTS_RECORD_SIZE;
+ }
+ if (space <= BTS_SAFETY_MARGIN) {
+ /* See if next phys buffer has more space */
+ next_buf = buf->cur_buf + 1;
+ if (next_buf >= buf->nr_bufs)
+ next_buf = 0;
+ next_phys = &buf->buf[next_buf];
+ gap = buf_size(phys->page) - phys->displacement - phys->size +
+ next_phys->displacement;
+ skip = pad + gap;
+ if (handle->size >= skip) {
+ next_space = next_phys->size;
+ if (next_space + skip > handle->size) {
+ next_space = handle->size - skip;
+ next_space -= next_space % BTS_RECORD_SIZE;
+ }
+ if (next_space > space || !space) {
+ if (pad)
+ bts_buffer_pad_out(phys, head);
+ ret = perf_aux_output_skip(handle, skip);
+ if (ret)
+ return ret;
+ /* Advance to next phys buffer */
+ phys = next_phys;
+ space = next_space;
+ head = phys->offset + phys->displacement;
+ /*
+ * After this, cur_buf and head won't match ds
+ * anymore, so we must not be racing with
+ * bts_update().
+ */
+ buf->cur_buf = next_buf;
+ local_set(&buf->head, head);
+ }
+ }
+ }
+
+ /* Don't go far beyond wakeup watermark */
+ wakeup = BTS_SAFETY_MARGIN + BTS_RECORD_SIZE + handle->wakeup -
+ handle->head;
+ if (space > wakeup) {
+ space = wakeup;
+ space -= space % BTS_RECORD_SIZE;
+ }
+
+ buf->end = head + space;
+
+ /*
+ * If we have no space, the lost notification would have been sent when
+ * we hit absolute_maximum - see bts_update()
+ */
+ if (!space)
+ return -ENOSPC;
+
+ return 0;
+}
+
+int intel_bts_interrupt(void)
+{
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+ struct perf_event *event = bts->handle.event;
+ struct bts_buffer *buf;
+ s64 old_head;
+ int err;
+
+ if (!event || !bts->started)
+ return 0;
+
+ buf = perf_get_aux(&bts->handle);
+ /*
+ * Skip snapshot counters: they don't use the interrupt, but
+ * there's no other way of telling, because the pointer will
+ * keep moving
+ */
+ if (!buf || buf->snapshot)
+ return 0;
+
+ old_head = local_read(&buf->head);
+ bts_update(bts);
+
+ /* no new data */
+ if (old_head == local_read(&buf->head))
+ return 0;
+
+ perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
+ !!local_xchg(&buf->lost, 0));
+
+ buf = perf_aux_output_begin(&bts->handle, event);
+ if (!buf)
+ return 1;
+
+ err = bts_buffer_reset(buf, &bts->handle);
+ if (err)
+ perf_aux_output_end(&bts->handle, 0, false);
+
+ return 1;
+}
+
+static void bts_event_del(struct perf_event *event, int mode)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+ struct bts_buffer *buf = perf_get_aux(&bts->handle);
+
+ bts_event_stop(event, PERF_EF_UPDATE);
+
+ if (buf) {
+ if (buf->snapshot)
+ bts->handle.head =
+ local_xchg(&buf->data_size,
+ buf->nr_pages << PAGE_SHIFT);
+ perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
+ !!local_xchg(&buf->lost, 0));
+ }
+
+ cpuc->ds->bts_index = bts->ds_back.bts_buffer_base;
+ cpuc->ds->bts_buffer_base = bts->ds_back.bts_buffer_base;
+ cpuc->ds->bts_absolute_maximum = bts->ds_back.bts_absolute_maximum;
+ cpuc->ds->bts_interrupt_threshold = bts->ds_back.bts_interrupt_threshold;
+}
+
+static int bts_event_add(struct perf_event *event, int mode)
+{
+ struct bts_buffer *buf;
+ struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ int ret = -EBUSY;
+
+ event->hw.state = PERF_HES_STOPPED;
+
+ if (test_bit(INTEL_PMC_IDX_FIXED_BTS, cpuc->active_mask))
+ return -EBUSY;
+
+ if (bts->handle.event)
+ return -EBUSY;
+
+ buf = perf_aux_output_begin(&bts->handle, event);
+ if (!buf)
+ return -EINVAL;
+
+ ret = bts_buffer_reset(buf, &bts->handle);
+ if (ret) {
+ perf_aux_output_end(&bts->handle, 0, false);
+ return ret;
+ }
+
+ bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base;
+ bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum;
+ bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold;
+
+ if (mode & PERF_EF_START) {
+ bts_event_start(event, 0);
+ if (hwc->state & PERF_HES_STOPPED) {
+ bts_event_del(event, 0);
+ return -EBUSY;
+ }
+ }
+
+ return 0;
+}
+
+static void bts_event_destroy(struct perf_event *event)
+{
+ x86_del_exclusive(x86_lbr_exclusive_bts);
+}
+
+static int bts_event_init(struct perf_event *event)
+{
+ if (event->attr.type != bts_pmu.type)
+ return -ENOENT;
+
+ if (x86_add_exclusive(x86_lbr_exclusive_bts))
+ return -EBUSY;
+
+ event->destroy = bts_event_destroy;
+
+ return 0;
+}
+
+static void bts_event_read(struct perf_event *event)
+{
+}
+
+static __init int bts_init(void)
+{
+ if (!boot_cpu_has(X86_FEATURE_DTES64) || !x86_pmu.bts)
+ return -ENODEV;
+
+ bts_pmu.capabilities = PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_ITRACE;
+ bts_pmu.task_ctx_nr = perf_sw_context;
+ bts_pmu.event_init = bts_event_init;
+ bts_pmu.add = bts_event_add;
+ bts_pmu.del = bts_event_del;
+ bts_pmu.start = bts_event_start;
+ bts_pmu.stop = bts_event_stop;
+ bts_pmu.read = bts_event_read;
+ bts_pmu.setup_aux = bts_buffer_setup_aux;
+ bts_pmu.free_aux = bts_buffer_free_aux;
+
+ return perf_pmu_register(&bts_pmu, "intel_bts", -1);
+}
+
+module_init(bts_init);
projects / cascardo / linux.git / blobdiff