1 files changed, 544 insertions, 0 deletions
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
new file mode 100644
index 000000000000..b99dc9258c0f
--- /dev/null
+++ b/arch/x86/events/intel/bts.c
@@ -0,0 +1,544 @@
+/*
+ * 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;
+
+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)(long)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.itrace_started = 1;
+	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_release_hardware();
+	x86_del_exclusive(x86_lbr_exclusive_bts);
+}
+
+static int bts_event_init(struct perf_event *event)
+{
+	int ret;
+
+	if (event->attr.type != bts_pmu.type)
+		return -ENOENT;
+
+	if (x86_add_exclusive(x86_lbr_exclusive_bts))
+		return -EBUSY;
+
+	/*
+	 * BTS leaks kernel addresses even when CPL0 tracing is
+	 * disabled, so disallow intel_bts driver for unprivileged
+	 * users on paranoid systems since it provides trace data
+	 * to the user in a zero-copy fashion.
+	 *
+	 * Note that the default paranoia setting permits unprivileged
+	 * users to profile the kernel.
+	 */
+	if (event->attr.exclude_kernel && perf_paranoid_kernel() &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	ret = x86_reserve_hardware();
+	if (ret) {
+		x86_del_exclusive(x86_lbr_exclusive_bts);
+		return ret;
+	}
+
+	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);
+}
+arch_initcall(bts_init);