intel-bts.c

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/*
 * 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;
}