/* SPDX-License-Identifier: GPL-2.0 */

#include "perf-sys.h"
#include "util/cloexec.h"
#include "util/evlist.h"
#include "util/evsel.h"
#include "util/parse-events.h"
#include "util/perf_api_probe.h"
#include <perf/cpumap.h>
#include <errno.h>

typedef void (*setup_probe_fn_t)(struct evsel *evsel);

static int perf_do_probe_api(setup_probe_fn_t fn, struct perf_cpu cpu, const char *str)
{
        struct evlist *evlist;
        struct evsel *evsel;
        unsigned long flags = perf_event_open_cloexec_flag();
        int err = -EAGAIN, fd;
        static pid_t pid = -1;

        evlist = evlist__new();
        if (!evlist)
                return -ENOMEM;

        if (parse_event(evlist, str))
                goto out_delete;

        evsel = evlist__first(evlist);

        while (1) {
                fd = sys_perf_event_open(&evsel->core.attr, pid, cpu.cpu, -1, flags);
                if (fd < 0) {
                        if (pid == -1 && errno == EACCES) {
                                pid = 0;
                                continue;
                        }
                        goto out_delete;
                }
                break;
        }
        close(fd);

        fn(evsel);

        fd = sys_perf_event_open(&evsel->core.attr, pid, cpu.cpu, -1, flags);
        if (fd < 0) {
                if (errno == EINVAL)
                        err = -EINVAL;
                goto out_delete;
        }
        close(fd);
        err = 0;

out_delete:
        evlist__delete(evlist);
        return err;
}

static bool perf_probe_api(setup_probe_fn_t fn)
{
        struct perf_pmu *pmu;
        struct perf_cpu_map *cpus;
        struct perf_cpu cpu;
        int ret = 0;

        cpus = perf_cpu_map__new_online_cpus();
        if (!cpus)
                return false;
        cpu = perf_cpu_map__cpu(cpus, 0);
        perf_cpu_map__put(cpus);

        ret = perf_do_probe_api(fn, cpu, "software/cpu-clock/u");
        if (!ret)
                return true;

        pmu = perf_pmus__scan_core(/*pmu=*/NULL);
        if (pmu) {
                const char *try[] = {"cycles", "instructions", NULL};
                char buf[256];
                int i = 0;

                while (ret == -EAGAIN && try[i]) {
                        snprintf(buf, sizeof(buf), "%s/%s/u", pmu->name, try[i++]);
                        ret = perf_do_probe_api(fn, cpu, buf);
                        if (!ret)
                                return true;
                }
        }
        return false;
}

static void perf_probe_sample_identifier(struct evsel *evsel)
{
        evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
}

static void perf_probe_comm_exec(struct evsel *evsel)
{
        evsel->core.attr.comm_exec = 1;
}

static void perf_probe_context_switch(struct evsel *evsel)
{
        evsel->core.attr.context_switch = 1;
}

static void perf_probe_text_poke(struct evsel *evsel)
{
        evsel->core.attr.text_poke = 1;
}

static void perf_probe_build_id(struct evsel *evsel)
{
        evsel->core.attr.build_id = 1;
}

static void perf_probe_cgroup(struct evsel *evsel)
{
        evsel->core.attr.cgroup = 1;
}

bool perf_can_sample_identifier(void)
{
        return perf_probe_api(perf_probe_sample_identifier);
}

bool perf_can_comm_exec(void)
{
        return perf_probe_api(perf_probe_comm_exec);
}

bool perf_can_record_switch_events(void)
{
        return perf_probe_api(perf_probe_context_switch);
}

bool perf_can_record_text_poke_events(void)
{
        return perf_probe_api(perf_probe_text_poke);
}

bool perf_can_record_cpu_wide(void)
{
        struct perf_event_attr attr = {
                .type = PERF_TYPE_SOFTWARE,
                .config = PERF_COUNT_SW_CPU_CLOCK,
                .exclude_kernel = 1,
        };
        struct perf_cpu_map *cpus;
        struct perf_cpu cpu;
        int fd;

        cpus = perf_cpu_map__new_online_cpus();
        if (!cpus)
                return false;

        cpu = perf_cpu_map__cpu(cpus, 0);
        perf_cpu_map__put(cpus);

        fd = sys_perf_event_open(&attr, -1, cpu.cpu, -1, 0);
        if (fd < 0)
                return false;
        close(fd);

        return true;
}

/*
 * Architectures are expected to know if AUX area sampling is supported by the
 * hardware. Here we check for kernel support.
 */
bool perf_can_aux_sample(void)
{
        struct perf_event_attr attr = {
                .size = sizeof(struct perf_event_attr),
                .exclude_kernel = 1,
                /*
                 * Non-zero value causes the kernel to calculate the effective
                 * attribute size up to that byte.
                 */
                .aux_sample_size = 1,
        };
        int fd;

        fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
        /*
         * If the kernel attribute is big enough to contain aux_sample_size
         * then we assume that it is supported. We are relying on the kernel to
         * validate the attribute size before anything else that could be wrong.
         */
        if (fd < 0 && errno == E2BIG)
                return false;
        if (fd >= 0)
                close(fd);

        return true;
}

bool perf_can_record_build_id(void)
{
        return perf_probe_api(perf_probe_build_id);
}

bool perf_can_record_cgroup(void)
{
        return perf_probe_api(perf_probe_cgroup);
}