auxtrace.c

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#include <stdbool.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/log2.h>

#include "../../util/evlist.h"
#include "../../util/auxtrace.h"
#include "../../util/evsel.h"

#define PERF_EVENT_CPUM_SF      0xB0000 /* Event: Basic-sampling */
#define PERF_EVENT_CPUM_SF_DIAG     0xBD000 /* Event: Combined-sampling */
#define DEFAULT_AUX_PAGES       128
#define DEFAULT_FREQ            4000

static void cpumsf_free(struct auxtrace_record *itr)
{
    free(itr);
}

static size_t cpumsf_info_priv_size(struct auxtrace_record *itr __maybe_unused,
                    struct perf_evlist *evlist __maybe_unused)
{
    return 0;
}

static int
cpumsf_info_fill(struct auxtrace_record *itr __maybe_unused,
         struct perf_session *session __maybe_unused,
         struct auxtrace_info_event *auxtrace_info __maybe_unused,
         size_t priv_size __maybe_unused)
{
    return 0;
}

static unsigned long
cpumsf_reference(struct auxtrace_record *itr __maybe_unused)
{
    return 0;
}

static int
cpumsf_recording_options(struct auxtrace_record *ar __maybe_unused,
             struct perf_evlist *evlist __maybe_unused,
             struct record_opts *opts)
{
    unsigned int factor = 1;
    unsigned int pages;

    opts->full_auxtrace = true;

    /*
     * The AUX buffer size should be set properly to avoid
     * overflow of samples if it is not set explicitly.
     * DEFAULT_AUX_PAGES is an proper size when sampling frequency
     * is DEFAULT_FREQ. It is expected to hold about 1/2 second
     * of sampling data. The size used for AUX buffer will scale
     * according to the specified frequency and DEFAULT_FREQ.
     */
    if (!opts->auxtrace_mmap_pages) {
        if (opts->user_freq != UINT_MAX)
            factor = (opts->user_freq + DEFAULT_FREQ
                  - 1) / DEFAULT_FREQ;
        pages = DEFAULT_AUX_PAGES * factor;
        opts->auxtrace_mmap_pages = roundup_pow_of_two(pages);
    }

    return 0;
}

static int
cpumsf_parse_snapshot_options(struct auxtrace_record *itr __maybe_unused,
                  struct record_opts *opts __maybe_unused,
                  const char *str __maybe_unused)
{
    return 0;
}

/*
 * auxtrace_record__init is called when perf record
 * check if the event really need auxtrace
 */
struct auxtrace_record *auxtrace_record__init(struct perf_evlist *evlist,
                          int *err)
{
    struct auxtrace_record *aux;
    struct perf_evsel *pos;
    int diagnose = 0;

    *err = 0;
    if (evlist->nr_entries == 0)
        return NULL;

    evlist__for_each_entry(evlist, pos) {
        if (pos->attr.config == PERF_EVENT_CPUM_SF_DIAG) {
            diagnose = 1;
            break;
        }
    }

    if (!diagnose)
        return NULL;

    /* sampling in diagnose mode. alloc aux buffer */
    aux = zalloc(sizeof(*aux));
    if (aux == NULL) {
        *err = -ENOMEM;
        return NULL;
    }

    aux->parse_snapshot_options = cpumsf_parse_snapshot_options;
    aux->recording_options = cpumsf_recording_options;
    aux->info_priv_size = cpumsf_info_priv_size;
    aux->info_fill = cpumsf_info_fill;
    aux->free = cpumsf_free;
    aux->reference = cpumsf_reference;

    return aux;
}