1 files changed, 1007 insertions, 0 deletions

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
new file mode 100644
index 000000000..2ca10d796
--- /dev/null
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -0,0 +1,1007 @@
+/*
+ * intel_pt.c: Intel Processor Trace support
+ * Copyright (c) 2013-2015, 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.
+ *
+ */
+
+#include <stdbool.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/log2.h>
+#include <cpuid.h>
+
+#include "../../perf.h"
+#include "../../util/session.h"
+#include "../../util/event.h"
+#include "../../util/evlist.h"
+#include "../../util/evsel.h"
+#include "../../util/cpumap.h"
+#include "../../util/parse-options.h"
+#include "../../util/parse-events.h"
+#include "../../util/pmu.h"
+#include "../../util/debug.h"
+#include "../../util/auxtrace.h"
+#include "../../util/tsc.h"
+#include "../../util/intel-pt.h"
+
+#define KiB(x) ((x) * 1024)
+#define MiB(x) ((x) * 1024 * 1024)
+#define KiB_MASK(x) (KiB(x) - 1)
+#define MiB_MASK(x) (MiB(x) - 1)
+
+#define INTEL_PT_DEFAULT_SAMPLE_SIZE	KiB(4)
+
+#define INTEL_PT_MAX_SAMPLE_SIZE	KiB(60)
+
+#define INTEL_PT_PSB_PERIOD_NEAR	256
+
+struct intel_pt_snapshot_ref {
+	void *ref_buf;
+	size_t ref_offset;
+	bool wrapped;
+};
+
+struct intel_pt_recording {
+	struct auxtrace_record		itr;
+	struct perf_pmu			*intel_pt_pmu;
+	int				have_sched_switch;
+	struct perf_evlist		*evlist;
+	bool				snapshot_mode;
+	bool				snapshot_init_done;
+	size_t				snapshot_size;
+	size_t				snapshot_ref_buf_size;
+	int				snapshot_ref_cnt;
+	struct intel_pt_snapshot_ref	*snapshot_refs;
+};
+
+static int intel_pt_parse_terms_with_default(struct list_head *formats,
+					     const char *str,
+					     u64 *config)
+{
+	struct list_head *terms;
+	struct perf_event_attr attr = { .size = 0, };
+	int err;
+
+	terms = malloc(sizeof(struct list_head));
+	if (!terms)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(terms);
+
+	err = parse_events_terms(terms, str);
+	if (err)
+		goto out_free;
+
+	attr.config = *config;
+	err = perf_pmu__config_terms(formats, &attr, terms, true, NULL);
+	if (err)
+		goto out_free;
+
+	*config = attr.config;
+out_free:
+	parse_events__free_terms(terms);
+	return err;
+}
+
+static int intel_pt_parse_terms(struct list_head *formats, const char *str,
+				u64 *config)
+{
+	*config = 0;
+	return intel_pt_parse_terms_with_default(formats, str, config);
+}
+
+static u64 intel_pt_masked_bits(u64 mask, u64 bits)
+{
+	const u64 top_bit = 1ULL << 63;
+	u64 res = 0;
+	int i;
+
+	for (i = 0; i < 64; i++) {
+		if (mask & top_bit) {
+			res <<= 1;
+			if (bits & top_bit)
+				res |= 1;
+		}
+		mask <<= 1;
+		bits <<= 1;
+	}
+
+	return res;
+}
+
+static int intel_pt_read_config(struct perf_pmu *intel_pt_pmu, const char *str,
+				struct perf_evlist *evlist, u64 *res)
+{
+	struct perf_evsel *evsel;
+	u64 mask;
+
+	*res = 0;
+
+	mask = perf_pmu__format_bits(&intel_pt_pmu->format, str);
+	if (!mask)
+		return -EINVAL;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->attr.type == intel_pt_pmu->type) {
+			*res = intel_pt_masked_bits(mask, evsel->attr.config);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static size_t intel_pt_psb_period(struct perf_pmu *intel_pt_pmu,
+				  struct perf_evlist *evlist)
+{
+	u64 val;
+	int err, topa_multiple_entries;
+	size_t psb_period;
+
+	if (perf_pmu__scan_file(intel_pt_pmu, "caps/topa_multiple_entries",
+				"%d", &topa_multiple_entries) != 1)
+		topa_multiple_entries = 0;
+
+	/*
+	 * Use caps/topa_multiple_entries to indicate early hardware that had
+	 * extra frequent PSBs.
+	 */
+	if (!topa_multiple_entries) {
+		psb_period = 256;
+		goto out;
+	}
+
+	err = intel_pt_read_config(intel_pt_pmu, "psb_period", evlist, &val);
+	if (err)
+		val = 0;
+
+	psb_period = 1 << (val + 11);
+out:
+	pr_debug2("%s psb_period %zu\n", intel_pt_pmu->name, psb_period);
+	return psb_period;
+}
+
+static int intel_pt_pick_bit(int bits, int target)
+{
+	int pos, pick = -1;
+
+	for (pos = 0; bits; bits >>= 1, pos++) {
+		if (bits & 1) {
+			if (pos <= target || pick < 0)
+				pick = pos;
+			if (pos >= target)
+				break;
+		}
+	}
+
+	return pick;
+}
+
+static u64 intel_pt_default_config(struct perf_pmu *intel_pt_pmu)
+{
+	char buf[256];
+	int mtc, mtc_periods = 0, mtc_period;
+	int psb_cyc, psb_periods, psb_period;
+	int pos = 0;
+	u64 config;
+
+	pos += scnprintf(buf + pos, sizeof(buf) - pos, "tsc");
+
+	if (perf_pmu__scan_file(intel_pt_pmu, "caps/mtc", "%d",
+				&mtc) != 1)
+		mtc = 1;
+
+	if (mtc) {
+		if (perf_pmu__scan_file(intel_pt_pmu, "caps/mtc_periods", "%x",
+					&mtc_periods) != 1)
+			mtc_periods = 0;
+		if (mtc_periods) {
+			mtc_period = intel_pt_pick_bit(mtc_periods, 3);
+			pos += scnprintf(buf + pos, sizeof(buf) - pos,
+					 ",mtc,mtc_period=%d", mtc_period);
+		}
+	}
+
+	if (perf_pmu__scan_file(intel_pt_pmu, "caps/psb_cyc", "%d",
+				&psb_cyc) != 1)
+		psb_cyc = 1;
+
+	if (psb_cyc && mtc_periods) {
+		if (perf_pmu__scan_file(intel_pt_pmu, "caps/psb_periods", "%x",
+					&psb_periods) != 1)
+			psb_periods = 0;
+		if (psb_periods) {
+			psb_period = intel_pt_pick_bit(psb_periods, 3);
+			pos += scnprintf(buf + pos, sizeof(buf) - pos,
+					 ",psb_period=%d", psb_period);
+		}
+	}
+
+	pr_debug2("%s default config: %s\n", intel_pt_pmu->name, buf);
+
+	intel_pt_parse_terms(&intel_pt_pmu->format, buf, &config);
+
+	return config;
+}
+
+static int intel_pt_parse_snapshot_options(struct auxtrace_record *itr,
+					   struct record_opts *opts,
+					   const char *str)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	unsigned long long snapshot_size = 0;
+	char *endptr;
+
+	if (str) {
+		snapshot_size = strtoull(str, &endptr, 0);
+		if (*endptr || snapshot_size > SIZE_MAX)
+			return -1;
+	}
+
+	opts->auxtrace_snapshot_mode = true;
+	opts->auxtrace_snapshot_size = snapshot_size;
+
+	ptr->snapshot_size = snapshot_size;
+
+	return 0;
+}
+
+struct perf_event_attr *
+intel_pt_pmu_default_config(struct perf_pmu *intel_pt_pmu)
+{
+	struct perf_event_attr *attr;
+
+	attr = zalloc(sizeof(struct perf_event_attr));
+	if (!attr)
+		return NULL;
+
+	attr->config = intel_pt_default_config(intel_pt_pmu);
+
+	intel_pt_pmu->selectable = true;
+
+	return attr;
+}
+
+static size_t intel_pt_info_priv_size(struct auxtrace_record *itr __maybe_unused)
+{
+	return INTEL_PT_AUXTRACE_PRIV_SIZE;
+}
+
+static void intel_pt_tsc_ctc_ratio(u32 *n, u32 *d)
+{
+	unsigned int eax = 0, ebx = 0, ecx = 0, edx = 0;
+
+	__get_cpuid(0x15, &eax, &ebx, &ecx, &edx);
+	*n = ebx;
+	*d = eax;
+}
+
+static int intel_pt_info_fill(struct auxtrace_record *itr,
+			      struct perf_session *session,
+			      struct auxtrace_info_event *auxtrace_info,
+			      size_t priv_size)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	struct perf_pmu *intel_pt_pmu = ptr->intel_pt_pmu;
+	struct perf_event_mmap_page *pc;
+	struct perf_tsc_conversion tc = { .time_mult = 0, };
+	bool cap_user_time_zero = false, per_cpu_mmaps;
+	u64 tsc_bit, mtc_bit, mtc_freq_bits, cyc_bit, noretcomp_bit;
+	u32 tsc_ctc_ratio_n, tsc_ctc_ratio_d;
+	int err;
+
+	if (priv_size != INTEL_PT_AUXTRACE_PRIV_SIZE)
+		return -EINVAL;
+
+	intel_pt_parse_terms(&intel_pt_pmu->format, "tsc", &tsc_bit);
+	intel_pt_parse_terms(&intel_pt_pmu->format, "noretcomp",
+			     &noretcomp_bit);
+	intel_pt_parse_terms(&intel_pt_pmu->format, "mtc", &mtc_bit);
+	mtc_freq_bits = perf_pmu__format_bits(&intel_pt_pmu->format,
+					      "mtc_period");
+	intel_pt_parse_terms(&intel_pt_pmu->format, "cyc", &cyc_bit);
+
+	intel_pt_tsc_ctc_ratio(&tsc_ctc_ratio_n, &tsc_ctc_ratio_d);
+
+	if (!session->evlist->nr_mmaps)
+		return -EINVAL;
+
+	pc = session->evlist->mmap[0].base;
+	if (pc) {
+		err = perf_read_tsc_conversion(pc, &tc);
+		if (err) {
+			if (err != -EOPNOTSUPP)
+				return err;
+		} else {
+			cap_user_time_zero = tc.time_mult != 0;
+		}
+		if (!cap_user_time_zero)
+			ui__warning("Intel Processor Trace: TSC not available\n");
+	}
+
+	per_cpu_mmaps = !cpu_map__empty(session->evlist->cpus);
+
+	auxtrace_info->type = PERF_AUXTRACE_INTEL_PT;
+	auxtrace_info->priv[INTEL_PT_PMU_TYPE] = intel_pt_pmu->type;
+	auxtrace_info->priv[INTEL_PT_TIME_SHIFT] = tc.time_shift;
+	auxtrace_info->priv[INTEL_PT_TIME_MULT] = tc.time_mult;
+	auxtrace_info->priv[INTEL_PT_TIME_ZERO] = tc.time_zero;
+	auxtrace_info->priv[INTEL_PT_CAP_USER_TIME_ZERO] = cap_user_time_zero;
+	auxtrace_info->priv[INTEL_PT_TSC_BIT] = tsc_bit;
+	auxtrace_info->priv[INTEL_PT_NORETCOMP_BIT] = noretcomp_bit;
+	auxtrace_info->priv[INTEL_PT_HAVE_SCHED_SWITCH] = ptr->have_sched_switch;
+	auxtrace_info->priv[INTEL_PT_SNAPSHOT_MODE] = ptr->snapshot_mode;
+	auxtrace_info->priv[INTEL_PT_PER_CPU_MMAPS] = per_cpu_mmaps;
+	auxtrace_info->priv[INTEL_PT_MTC_BIT] = mtc_bit;
+	auxtrace_info->priv[INTEL_PT_MTC_FREQ_BITS] = mtc_freq_bits;
+	auxtrace_info->priv[INTEL_PT_TSC_CTC_N] = tsc_ctc_ratio_n;
+	auxtrace_info->priv[INTEL_PT_TSC_CTC_D] = tsc_ctc_ratio_d;
+	auxtrace_info->priv[INTEL_PT_CYC_BIT] = cyc_bit;
+
+	return 0;
+}
+
+static int intel_pt_track_switches(struct perf_evlist *evlist)
+{
+	const char *sched_switch = "sched:sched_switch";
+	struct perf_evsel *evsel;
+	int err;
+
+	if (!perf_evlist__can_select_event(evlist, sched_switch))
+		return -EPERM;
+
+	err = parse_events(evlist, sched_switch, NULL);
+	if (err) {
+		pr_debug2("%s: failed to parse %s, error %d\n",
+			  __func__, sched_switch, err);
+		return err;
+	}
+
+	evsel = perf_evlist__last(evlist);
+
+	perf_evsel__set_sample_bit(evsel, CPU);
+	perf_evsel__set_sample_bit(evsel, TIME);
+
+	evsel->system_wide = true;
+	evsel->no_aux_samples = true;
+	evsel->immediate = true;
+
+	return 0;
+}
+
+static void intel_pt_valid_str(char *str, size_t len, u64 valid)
+{
+	unsigned int val, last = 0, state = 1;
+	int p = 0;
+
+	str[0] = '\0';
+
+	for (val = 0; val <= 64; val++, valid >>= 1) {
+		if (valid & 1) {
+			last = val;
+			switch (state) {
+			case 0:
+				p += scnprintf(str + p, len - p, ",");
+				/* Fall through */
+			case 1:
+				p += scnprintf(str + p, len - p, "%u", val);
+				state = 2;
+				break;
+			case 2:
+				state = 3;
+				break;
+			case 3:
+				state = 4;
+				break;
+			default:
+				break;
+			}
+		} else {
+			switch (state) {
+			case 3:
+				p += scnprintf(str + p, len - p, ",%u", last);
+				state = 0;
+				break;
+			case 4:
+				p += scnprintf(str + p, len - p, "-%u", last);
+				state = 0;
+				break;
+			default:
+				break;
+			}
+			if (state != 1)
+				state = 0;
+		}
+	}
+}
+
+static int intel_pt_val_config_term(struct perf_pmu *intel_pt_pmu,
+				    const char *caps, const char *name,
+				    const char *supported, u64 config)
+{
+	char valid_str[256];
+	unsigned int shift;
+	unsigned long long valid;
+	u64 bits;
+	int ok;
+
+	if (perf_pmu__scan_file(intel_pt_pmu, caps, "%llx", &valid) != 1)
+		valid = 0;
+
+	if (supported &&
+	    perf_pmu__scan_file(intel_pt_pmu, supported, "%d", &ok) == 1 && !ok)
+		valid = 0;
+
+	valid |= 1;
+
+	bits = perf_pmu__format_bits(&intel_pt_pmu->format, name);
+
+	config &= bits;
+
+	for (shift = 0; bits && !(bits & 1); shift++)
+		bits >>= 1;
+
+	config >>= shift;
+
+	if (config > 63)
+		goto out_err;
+
+	if (valid & (1 << config))
+		return 0;
+out_err:
+	intel_pt_valid_str(valid_str, sizeof(valid_str), valid);
+	pr_err("Invalid %s for %s. Valid values are: %s\n",
+	       name, INTEL_PT_PMU_NAME, valid_str);
+	return -EINVAL;
+}
+
+static int intel_pt_validate_config(struct perf_pmu *intel_pt_pmu,
+				    struct perf_evsel *evsel)
+{
+	int err;
+
+	if (!evsel)
+		return 0;
+
+	err = intel_pt_val_config_term(intel_pt_pmu, "caps/cycle_thresholds",
+				       "cyc_thresh", "caps/psb_cyc",
+				       evsel->attr.config);
+	if (err)
+		return err;
+
+	err = intel_pt_val_config_term(intel_pt_pmu, "caps/mtc_periods",
+				       "mtc_period", "caps/mtc",
+				       evsel->attr.config);
+	if (err)
+		return err;
+
+	return intel_pt_val_config_term(intel_pt_pmu, "caps/psb_periods",
+					"psb_period", "caps/psb_cyc",
+					evsel->attr.config);
+}
+
+static int intel_pt_recording_options(struct auxtrace_record *itr,
+				      struct perf_evlist *evlist,
+				      struct record_opts *opts)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	struct perf_pmu *intel_pt_pmu = ptr->intel_pt_pmu;
+	bool have_timing_info;
+	struct perf_evsel *evsel, *intel_pt_evsel = NULL;
+	const struct cpu_map *cpus = evlist->cpus;
+	bool privileged = geteuid() == 0 || perf_event_paranoid() < 0;
+	u64 tsc_bit;
+	int err;
+
+	ptr->evlist = evlist;
+	ptr->snapshot_mode = opts->auxtrace_snapshot_mode;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->attr.type == intel_pt_pmu->type) {
+			if (intel_pt_evsel) {
+				pr_err("There may be only one " INTEL_PT_PMU_NAME " event\n");
+				return -EINVAL;
+			}
+			evsel->attr.freq = 0;
+			evsel->attr.sample_period = 1;
+			intel_pt_evsel = evsel;
+			opts->full_auxtrace = true;
+		}
+	}
+
+	if (opts->auxtrace_snapshot_mode && !opts->full_auxtrace) {
+		pr_err("Snapshot mode (-S option) requires " INTEL_PT_PMU_NAME " PMU event (-e " INTEL_PT_PMU_NAME ")\n");
+		return -EINVAL;
+	}
+
+	if (opts->use_clockid) {
+		pr_err("Cannot use clockid (-k option) with " INTEL_PT_PMU_NAME "\n");
+		return -EINVAL;
+	}
+
+	if (!opts->full_auxtrace)
+		return 0;
+
+	err = intel_pt_validate_config(intel_pt_pmu, intel_pt_evsel);
+	if (err)
+		return err;
+
+	/* Set default sizes for snapshot mode */
+	if (opts->auxtrace_snapshot_mode) {
+		size_t psb_period = intel_pt_psb_period(intel_pt_pmu, evlist);
+
+		if (!opts->auxtrace_snapshot_size && !opts->auxtrace_mmap_pages) {
+			if (privileged) {
+				opts->auxtrace_mmap_pages = MiB(4) / page_size;
+			} else {
+				opts->auxtrace_mmap_pages = KiB(128) / page_size;
+				if (opts->mmap_pages == UINT_MAX)
+					opts->mmap_pages = KiB(256) / page_size;
+			}
+		} else if (!opts->auxtrace_mmap_pages && !privileged &&
+			   opts->mmap_pages == UINT_MAX) {
+			opts->mmap_pages = KiB(256) / page_size;
+		}
+		if (!opts->auxtrace_snapshot_size)
+			opts->auxtrace_snapshot_size =
+				opts->auxtrace_mmap_pages * (size_t)page_size;
+		if (!opts->auxtrace_mmap_pages) {
+			size_t sz = opts->auxtrace_snapshot_size;
+
+			sz = round_up(sz, page_size) / page_size;
+			opts->auxtrace_mmap_pages = roundup_pow_of_two(sz);
+		}
+		if (opts->auxtrace_snapshot_size >
+				opts->auxtrace_mmap_pages * (size_t)page_size) {
+			pr_err("Snapshot size %zu must not be greater than AUX area tracing mmap size %zu\n",
+			       opts->auxtrace_snapshot_size,
+			       opts->auxtrace_mmap_pages * (size_t)page_size);
+			return -EINVAL;
+		}
+		if (!opts->auxtrace_snapshot_size || !opts->auxtrace_mmap_pages) {
+			pr_err("Failed to calculate default snapshot size and/or AUX area tracing mmap pages\n");
+			return -EINVAL;
+		}
+		pr_debug2("Intel PT snapshot size: %zu\n",
+			  opts->auxtrace_snapshot_size);
+		if (psb_period &&
+		    opts->auxtrace_snapshot_size <= psb_period +
+						  INTEL_PT_PSB_PERIOD_NEAR)
+			ui__warning("Intel PT snapshot size (%zu) may be too small for PSB period (%zu)\n",
+				    opts->auxtrace_snapshot_size, psb_period);
+	}
+
+	/* Set default sizes for full trace mode */
+	if (opts->full_auxtrace && !opts->auxtrace_mmap_pages) {
+		if (privileged) {
+			opts->auxtrace_mmap_pages = MiB(4) / page_size;
+		} else {
+			opts->auxtrace_mmap_pages = KiB(128) / page_size;
+			if (opts->mmap_pages == UINT_MAX)
+				opts->mmap_pages = KiB(256) / page_size;
+		}
+	}
+
+	/* Validate auxtrace_mmap_pages */
+	if (opts->auxtrace_mmap_pages) {
+		size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;
+		size_t min_sz;
+
+		if (opts->auxtrace_snapshot_mode)
+			min_sz = KiB(4);
+		else
+			min_sz = KiB(8);
+
+		if (sz < min_sz || !is_power_of_2(sz)) {
+			pr_err("Invalid mmap size for Intel Processor Trace: must be at least %zuKiB and a power of 2\n",
+			       min_sz / 1024);
+			return -EINVAL;
+		}
+	}
+
+	intel_pt_parse_terms(&intel_pt_pmu->format, "tsc", &tsc_bit);
+
+	if (opts->full_auxtrace && (intel_pt_evsel->attr.config & tsc_bit))
+		have_timing_info = true;
+	else
+		have_timing_info = false;
+
+	/*
+	 * Per-cpu recording needs sched_switch events to distinguish different
+	 * threads.
+	 */
+	if (have_timing_info && !cpu_map__empty(cpus)) {
+		err = intel_pt_track_switches(evlist);
+		if (err == -EPERM)
+			pr_debug2("Unable to select sched:sched_switch\n");
+		else if (err)
+			return err;
+		else
+			ptr->have_sched_switch = 1;
+	}
+
+	if (intel_pt_evsel) {
+		/*
+		 * To obtain the auxtrace buffer file descriptor, the auxtrace
+		 * event must come first.
+		 */
+		perf_evlist__to_front(evlist, intel_pt_evsel);
+		/*
+		 * In the case of per-cpu mmaps, we need the CPU on the
+		 * AUX event.
+		 */
+		if (!cpu_map__empty(cpus))
+			perf_evsel__set_sample_bit(intel_pt_evsel, CPU);
+	}
+
+	/* Add dummy event to keep tracking */
+	if (opts->full_auxtrace) {
+		struct perf_evsel *tracking_evsel;
+
+		err = parse_events(evlist, "dummy:u", NULL);
+		if (err)
+			return err;
+
+		tracking_evsel = perf_evlist__last(evlist);
+
+		perf_evlist__set_tracking_event(evlist, tracking_evsel);
+
+		tracking_evsel->attr.freq = 0;
+		tracking_evsel->attr.sample_period = 1;
+
+		/* In per-cpu case, always need the time of mmap events etc */
+		if (!cpu_map__empty(cpus))
+			perf_evsel__set_sample_bit(tracking_evsel, TIME);
+	}
+
+	/*
+	 * Warn the user when we do not have enough information to decode i.e.
+	 * per-cpu with no sched_switch (except workload-only).
+	 */
+	if (!ptr->have_sched_switch && !cpu_map__empty(cpus) &&
+	    !target__none(&opts->target))
+		ui__warning("Intel Processor Trace decoding will not be possible except for kernel tracing!\n");
+
+	return 0;
+}
+
+static int intel_pt_snapshot_start(struct auxtrace_record *itr)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	struct perf_evsel *evsel;
+
+	evlist__for_each(ptr->evlist, evsel) {
+		if (evsel->attr.type == ptr->intel_pt_pmu->type)
+			return perf_evlist__disable_event(ptr->evlist, evsel);
+	}
+	return -EINVAL;
+}
+
+static int intel_pt_snapshot_finish(struct auxtrace_record *itr)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	struct perf_evsel *evsel;
+
+	evlist__for_each(ptr->evlist, evsel) {
+		if (evsel->attr.type == ptr->intel_pt_pmu->type)
+			return perf_evlist__enable_event(ptr->evlist, evsel);
+	}
+	return -EINVAL;
+}
+
+static int intel_pt_alloc_snapshot_refs(struct intel_pt_recording *ptr, int idx)
+{
+	const size_t sz = sizeof(struct intel_pt_snapshot_ref);
+	int cnt = ptr->snapshot_ref_cnt, new_cnt = cnt * 2;
+	struct intel_pt_snapshot_ref *refs;
+
+	if (!new_cnt)
+		new_cnt = 16;
+
+	while (new_cnt <= idx)
+		new_cnt *= 2;
+
+	refs = calloc(new_cnt, sz);
+	if (!refs)
+		return -ENOMEM;
+
+	memcpy(refs, ptr->snapshot_refs, cnt * sz);
+
+	ptr->snapshot_refs = refs;
+	ptr->snapshot_ref_cnt = new_cnt;
+
+	return 0;
+}
+
+static void intel_pt_free_snapshot_refs(struct intel_pt_recording *ptr)
+{
+	int i;
+
+	for (i = 0; i < ptr->snapshot_ref_cnt; i++)
+		zfree(&ptr->snapshot_refs[i].ref_buf);
+	zfree(&ptr->snapshot_refs);
+}
+
+static void intel_pt_recording_free(struct auxtrace_record *itr)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+
+	intel_pt_free_snapshot_refs(ptr);
+	free(ptr);
+}
+
+static int intel_pt_alloc_snapshot_ref(struct intel_pt_recording *ptr, int idx,
+				       size_t snapshot_buf_size)
+{
+	size_t ref_buf_size = ptr->snapshot_ref_buf_size;
+	void *ref_buf;
+
+	ref_buf = zalloc(ref_buf_size);
+	if (!ref_buf)
+		return -ENOMEM;
+
+	ptr->snapshot_refs[idx].ref_buf = ref_buf;
+	ptr->snapshot_refs[idx].ref_offset = snapshot_buf_size - ref_buf_size;
+
+	return 0;
+}
+
+static size_t intel_pt_snapshot_ref_buf_size(struct intel_pt_recording *ptr,
+					     size_t snapshot_buf_size)
+{
+	const size_t max_size = 256 * 1024;
+	size_t buf_size = 0, psb_period;
+
+	if (ptr->snapshot_size <= 64 * 1024)
+		return 0;
+
+	psb_period = intel_pt_psb_period(ptr->intel_pt_pmu, ptr->evlist);
+	if (psb_period)
+		buf_size = psb_period * 2;
+
+	if (!buf_size || buf_size > max_size)
+		buf_size = max_size;
+
+	if (buf_size >= snapshot_buf_size)
+		return 0;
+
+	if (buf_size >= ptr->snapshot_size / 2)
+		return 0;
+
+	return buf_size;
+}
+
+static int intel_pt_snapshot_init(struct intel_pt_recording *ptr,
+				  size_t snapshot_buf_size)
+{
+	if (ptr->snapshot_init_done)
+		return 0;
+
+	ptr->snapshot_init_done = true;
+
+	ptr->snapshot_ref_buf_size = intel_pt_snapshot_ref_buf_size(ptr,
+							snapshot_buf_size);
+
+	return 0;
+}
+
+/**
+ * intel_pt_compare_buffers - compare bytes in a buffer to a circular buffer.
+ * @buf1: first buffer
+ * @compare_size: number of bytes to compare
+ * @buf2: second buffer (a circular buffer)
+ * @offs2: offset in second buffer
+ * @buf2_size: size of second buffer
+ *
+ * The comparison allows for the possibility that the bytes to compare in the
+ * circular buffer are not contiguous.  It is assumed that @compare_size <=
+ * @buf2_size.  This function returns %false if the bytes are identical, %true
+ * otherwise.
+ */
+static bool intel_pt_compare_buffers(void *buf1, size_t compare_size,
+				     void *buf2, size_t offs2, size_t buf2_size)
+{
+	size_t end2 = offs2 + compare_size, part_size;
+
+	if (end2 <= buf2_size)
+		return memcmp(buf1, buf2 + offs2, compare_size);
+
+	part_size = end2 - buf2_size;
+	if (memcmp(buf1, buf2 + offs2, part_size))
+		return true;
+
+	compare_size -= part_size;
+
+	return memcmp(buf1 + part_size, buf2, compare_size);
+}
+
+static bool intel_pt_compare_ref(void *ref_buf, size_t ref_offset,
+				 size_t ref_size, size_t buf_size,
+				 void *data, size_t head)
+{
+	size_t ref_end = ref_offset + ref_size;
+
+	if (ref_end > buf_size) {
+		if (head > ref_offset || head < ref_end - buf_size)
+			return true;
+	} else if (head > ref_offset && head < ref_end) {
+		return true;
+	}
+
+	return intel_pt_compare_buffers(ref_buf, ref_size, data, ref_offset,
+					buf_size);
+}
+
+static void intel_pt_copy_ref(void *ref_buf, size_t ref_size, size_t buf_size,
+			      void *data, size_t head)
+{
+	if (head >= ref_size) {
+		memcpy(ref_buf, data + head - ref_size, ref_size);
+	} else {
+		memcpy(ref_buf, data, head);
+		ref_size -= head;
+		memcpy(ref_buf + head, data + buf_size - ref_size, ref_size);
+	}
+}
+
+static bool intel_pt_wrapped(struct intel_pt_recording *ptr, int idx,
+			     struct auxtrace_mmap *mm, unsigned char *data,
+			     u64 head)
+{
+	struct intel_pt_snapshot_ref *ref = &ptr->snapshot_refs[idx];
+	bool wrapped;
+
+	wrapped = intel_pt_compare_ref(ref->ref_buf, ref->ref_offset,
+				       ptr->snapshot_ref_buf_size, mm->len,
+				       data, head);
+
+	intel_pt_copy_ref(ref->ref_buf, ptr->snapshot_ref_buf_size, mm->len,
+			  data, head);
+
+	return wrapped;
+}
+
+static bool intel_pt_first_wrap(u64 *data, size_t buf_size)
+{
+	int i, a, b;
+
+	b = buf_size >> 3;
+	a = b - 512;
+	if (a < 0)
+		a = 0;
+
+	for (i = a; i < b; i++) {
+		if (data[i])
+			return true;
+	}
+
+	return false;
+}
+
+static int intel_pt_find_snapshot(struct auxtrace_record *itr, int idx,
+				  struct auxtrace_mmap *mm, unsigned char *data,
+				  u64 *head, u64 *old)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	bool wrapped;
+	int err;
+
+	pr_debug3("%s: mmap index %d old head %zu new head %zu\n",
+		  __func__, idx, (size_t)*old, (size_t)*head);
+
+	err = intel_pt_snapshot_init(ptr, mm->len);
+	if (err)
+		goto out_err;
+
+	if (idx >= ptr->snapshot_ref_cnt) {
+		err = intel_pt_alloc_snapshot_refs(ptr, idx);
+		if (err)
+			goto out_err;
+	}
+
+	if (ptr->snapshot_ref_buf_size) {
+		if (!ptr->snapshot_refs[idx].ref_buf) {
+			err = intel_pt_alloc_snapshot_ref(ptr, idx, mm->len);
+			if (err)
+				goto out_err;
+		}
+		wrapped = intel_pt_wrapped(ptr, idx, mm, data, *head);
+	} else {
+		wrapped = ptr->snapshot_refs[idx].wrapped;
+		if (!wrapped && intel_pt_first_wrap((u64 *)data, mm->len)) {
+			ptr->snapshot_refs[idx].wrapped = true;
+			wrapped = true;
+		}
+	}
+
+	/*
+	 * In full trace mode 'head' continually increases.  However in snapshot
+	 * mode 'head' is an offset within the buffer.  Here 'old' and 'head'
+	 * are adjusted to match the full trace case which expects that 'old' is
+	 * always less than 'head'.
+	 */
+	if (wrapped) {
+		*old = *head;
+		*head += mm->len;
+	} else {
+		if (mm->mask)
+			*old &= mm->mask;
+		else
+			*old %= mm->len;
+		if (*old > *head)
+			*head += mm->len;
+	}
+
+	pr_debug3("%s: wrap-around %sdetected, adjusted old head %zu adjusted new head %zu\n",
+		  __func__, wrapped ? "" : "not ", (size_t)*old, (size_t)*head);
+
+	return 0;
+
+out_err:
+	pr_err("%s: failed, error %d\n", __func__, err);
+	return err;
+}
+
+static u64 intel_pt_reference(struct auxtrace_record *itr __maybe_unused)
+{
+	return rdtsc();
+}
+
+static int intel_pt_read_finish(struct auxtrace_record *itr, int idx)
+{
+	struct intel_pt_recording *ptr =
+			container_of(itr, struct intel_pt_recording, itr);
+	struct perf_evsel *evsel;
+
+	evlist__for_each(ptr->evlist, evsel) {
+		if (evsel->attr.type == ptr->intel_pt_pmu->type)
+			return perf_evlist__enable_event_idx(ptr->evlist, evsel,
+							     idx);
+	}
+	return -EINVAL;
+}
+
+struct auxtrace_record *intel_pt_recording_init(int *err)
+{
+	struct perf_pmu *intel_pt_pmu = perf_pmu__find(INTEL_PT_PMU_NAME);
+	struct intel_pt_recording *ptr;
+
+	if (!intel_pt_pmu)
+		return NULL;
+
+	ptr = zalloc(sizeof(struct intel_pt_recording));
+	if (!ptr) {
+		*err = -ENOMEM;
+		return NULL;
+	}
+
+	ptr->intel_pt_pmu = intel_pt_pmu;
+	ptr->itr.recording_options = intel_pt_recording_options;
+	ptr->itr.info_priv_size = intel_pt_info_priv_size;
+	ptr->itr.info_fill = intel_pt_info_fill;
+	ptr->itr.free = intel_pt_recording_free;
+	ptr->itr.snapshot_start = intel_pt_snapshot_start;
+	ptr->itr.snapshot_finish = intel_pt_snapshot_finish;
+	ptr->itr.find_snapshot = intel_pt_find_snapshot;
+	ptr->itr.parse_snapshot_options = intel_pt_parse_snapshot_options;
+	ptr->itr.reference = intel_pt_reference;
+	ptr->itr.read_finish = intel_pt_read_finish;
+	return &ptr->itr;
+}