text: /*
   * intel-bts.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 <errno.h>
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/bitops.h>
  #include <linux/log2.h>
  
  #include "../../util/cpumap.h"
  #include "../../util/evsel.h"
  #include "../../util/evlist.h"
  #include "../../util/session.h"
  #include "../../util/util.h"
  #include "../../util/pmu.h"
  #include "../../util/debug.h"
  #include "../../util/tsc.h"
  #include "../../util/auxtrace.h"
  #include "../../util/intel-bts.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)
  
  struct intel_bts_snapshot_ref {
  	void	*ref_buf;
  	size_t	ref_offset;
  	bool	wrapped;
  };
  
  struct intel_bts_recording {
  	struct auxtrace_record		itr;
  	struct perf_pmu			*intel_bts_pmu;
  	struct perf_evlist		*evlist;
  	bool				snapshot_mode;
  	size_t				snapshot_size;
  	int				snapshot_ref_cnt;
  	struct intel_bts_snapshot_ref	*snapshot_refs;
  };
  
  struct branch {
  	u64 from;
  	u64 to;
  	u64 misc;
  };
  
  static size_t
  intel_bts_info_priv_size(struct auxtrace_record *itr __maybe_unused,
  			 struct perf_evlist *evlist __maybe_unused)
  {
  	return INTEL_BTS_AUXTRACE_PRIV_SIZE;
  }
  
  static int intel_bts_info_fill(struct auxtrace_record *itr,
  			       struct perf_session *session,
  			       struct auxtrace_info_event *auxtrace_info,
  			       size_t priv_size)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_recording, itr);
  	struct perf_pmu *intel_bts_pmu = btsr->intel_bts_pmu;
  	struct perf_event_mmap_page *pc;
  	struct perf_tsc_conversion tc = { .time_mult = 0, };
  	bool cap_user_time_zero = false;
  	int err;
  
  	if (priv_size != INTEL_BTS_AUXTRACE_PRIV_SIZE)
  		return -EINVAL;
  
  	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 BTS: TSC not available\n");
  	}
  
  	auxtrace_info->type = PERF_AUXTRACE_INTEL_BTS;
  	auxtrace_info->priv[INTEL_BTS_PMU_TYPE] = intel_bts_pmu->type;
  	auxtrace_info->priv[INTEL_BTS_TIME_SHIFT] = tc.time_shift;
  	auxtrace_info->priv[INTEL_BTS_TIME_MULT] = tc.time_mult;
  	auxtrace_info->priv[INTEL_BTS_TIME_ZERO] = tc.time_zero;
  	auxtrace_info->priv[INTEL_BTS_CAP_USER_TIME_ZERO] = cap_user_time_zero;
  	auxtrace_info->priv[INTEL_BTS_SNAPSHOT_MODE] = btsr->snapshot_mode;
  
  	return 0;
  }
  
  static int intel_bts_recording_options(struct auxtrace_record *itr,
  				       struct perf_evlist *evlist,
  				       struct record_opts *opts)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_recording, itr);
  	struct perf_pmu *intel_bts_pmu = btsr->intel_bts_pmu;
  	struct perf_evsel *evsel, *intel_bts_evsel = NULL;
  	const struct cpu_map *cpus = evlist->cpus;
  	bool privileged = geteuid() == 0 || perf_event_paranoid() < 0;
  
  	btsr->evlist = evlist;
  	btsr->snapshot_mode = opts->auxtrace_snapshot_mode;
  
  	evlist__for_each_entry(evlist, evsel) {
  		if (evsel->attr.type == intel_bts_pmu->type) {
  			if (intel_bts_evsel) {
  				pr_err("There may be only one " INTEL_BTS_PMU_NAME " event\n");
  				return -EINVAL;
  			}
  			evsel->attr.freq = 0;
  			evsel->attr.sample_period = 1;
  			intel_bts_evsel = evsel;
  			opts->full_auxtrace = true;
  		}
  	}
  
  	if (opts->auxtrace_snapshot_mode && !opts->full_auxtrace) {
  		pr_err("Snapshot mode (-S option) requires " INTEL_BTS_PMU_NAME " PMU event (-e " INTEL_BTS_PMU_NAME ")\n");
  		return -EINVAL;
  	}
  
  	if (!opts->full_auxtrace)
  		return 0;
  
  	if (opts->full_auxtrace && !cpu_map__empty(cpus)) {
  		pr_err(INTEL_BTS_PMU_NAME " does not support per-cpu recording\n");
  		return -EINVAL;
  	}
  
  	/* Set default sizes for snapshot mode */
  	if (opts->auxtrace_snapshot_mode) {
  		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 BTS snapshot size: %zu\n",
  			  opts->auxtrace_snapshot_size);
  	}
  
  	/* 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 BTS: must be at least %zuKiB and a power of 2\n",
  			       min_sz / 1024);
  			return -EINVAL;
  		}
  	}
  
  	if (intel_bts_evsel) {
  		/*
  		 * To obtain the auxtrace buffer file descriptor, the auxtrace event
  		 * must come first.
  		 */
  		perf_evlist__to_front(evlist, intel_bts_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_bts_evsel, CPU);
  	}
  
  	/* Add dummy event to keep tracking */
  	if (opts->full_auxtrace) {
  		struct perf_evsel *tracking_evsel;
  		int err;
  
  		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;
  	}
  
  	return 0;
  }
  
  static int intel_bts_parse_snapshot_options(struct auxtrace_record *itr,
  					    struct record_opts *opts,
  					    const char *str)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_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;
  
  	btsr->snapshot_size = snapshot_size;
  
  	return 0;
  }
  
  static u64 intel_bts_reference(struct auxtrace_record *itr __maybe_unused)
  {
  	return rdtsc();
  }
  
  static int intel_bts_alloc_snapshot_refs(struct intel_bts_recording *btsr,
  					 int idx)
  {
  	const size_t sz = sizeof(struct intel_bts_snapshot_ref);
  	int cnt = btsr->snapshot_ref_cnt, new_cnt = cnt * 2;
  	struct intel_bts_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, btsr->snapshot_refs, cnt * sz);
  
  	btsr->snapshot_refs = refs;
  	btsr->snapshot_ref_cnt = new_cnt;
  
  	return 0;
  }
  
  static void intel_bts_free_snapshot_refs(struct intel_bts_recording *btsr)
  {
  	int i;
  
  	for (i = 0; i < btsr->snapshot_ref_cnt; i++)
  		zfree(&btsr->snapshot_refs[i].ref_buf);
  	zfree(&btsr->snapshot_refs);
  }
  
  static void intel_bts_recording_free(struct auxtrace_record *itr)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_recording, itr);
  
  	intel_bts_free_snapshot_refs(btsr);
  	free(btsr);
  }
  
  static int intel_bts_snapshot_start(struct auxtrace_record *itr)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_recording, itr);
  	struct perf_evsel *evsel;
  
  	evlist__for_each_entry(btsr->evlist, evsel) {
  		if (evsel->attr.type == btsr->intel_bts_pmu->type)
  			return perf_evsel__disable(evsel);
  	}
  	return -EINVAL;
  }
  
  static int intel_bts_snapshot_finish(struct auxtrace_record *itr)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_recording, itr);
  	struct perf_evsel *evsel;
  
  	evlist__for_each_entry(btsr->evlist, evsel) {
  		if (evsel->attr.type == btsr->intel_bts_pmu->type)
  			return perf_evsel__enable(evsel);
  	}
  	return -EINVAL;
  }
  
  static bool intel_bts_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_bts_find_snapshot(struct auxtrace_record *itr, int idx,
  				   struct auxtrace_mmap *mm, unsigned char *data,
  				   u64 *head, u64 *old)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_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);
  
  	if (idx >= btsr->snapshot_ref_cnt) {
  		err = intel_bts_alloc_snapshot_refs(btsr, idx);
  		if (err)
  			goto out_err;
  	}
  
  	wrapped = btsr->snapshot_refs[idx].wrapped;
  	if (!wrapped && intel_bts_first_wrap((u64 *)data, mm->len)) {
  		btsr->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 int intel_bts_read_finish(struct auxtrace_record *itr, int idx)
  {
  	struct intel_bts_recording *btsr =
  			container_of(itr, struct intel_bts_recording, itr);
  	struct perf_evsel *evsel;
  
  	evlist__for_each_entry(btsr->evlist, evsel) {
  		if (evsel->attr.type == btsr->intel_bts_pmu->type)
  			return perf_evlist__enable_event_idx(btsr->evlist,
  							     evsel, idx);
  	}
  	return -EINVAL;
  }
  
  struct auxtrace_record *intel_bts_recording_init(int *err)
  {
  	struct perf_pmu *intel_bts_pmu = perf_pmu__find(INTEL_BTS_PMU_NAME);
  	struct intel_bts_recording *btsr;
  
  	if (!intel_bts_pmu)
  		return NULL;
  
  	if (setenv("JITDUMP_USE_ARCH_TIMESTAMP", "1", 1)) {
  		*err = -errno;
  		return NULL;
  	}
  
  	btsr = zalloc(sizeof(struct intel_bts_recording));
  	if (!btsr) {
  		*err = -ENOMEM;
  		return NULL;
  	}
  
  	btsr->intel_bts_pmu = intel_bts_pmu;
  	btsr->itr.recording_options = intel_bts_recording_options;
  	btsr->itr.info_priv_size = intel_bts_info_priv_size;
  	btsr->itr.info_fill = intel_bts_info_fill;
  	btsr->itr.free = intel_bts_recording_free;
  	btsr->itr.snapshot_start = intel_bts_snapshot_start;
  	btsr->itr.snapshot_finish = intel_bts_snapshot_finish;
  	btsr->itr.find_snapshot = intel_bts_find_snapshot;
  	btsr->itr.parse_snapshot_options = intel_bts_parse_snapshot_options;
  	btsr->itr.reference = intel_bts_reference;
  	btsr->itr.read_finish = intel_bts_read_finish;
  	btsr->itr.alignment = sizeof(struct branch);
  	return &btsr->itr;
  }
  