// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright(C) 2015 Linaro Limited. All rights reserved.
 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
 */

#include <api/fs/fs.h>
#include <linux/bits.h>
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <linux/coresight-pmu.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/types.h>
#include <linux/zalloc.h>

#include "cs-etm.h"
#include "../../perf.h"
#include "../../util/auxtrace.h"
#include "../../util/cpumap.h"
#include "../../util/evlist.h"
#include "../../util/evsel.h"
#include "../../util/pmu.h"
#include "../../util/thread_map.h"
#include "../../util/cs-etm.h"
#include "../../util/util.h"

#include <errno.h>
#include <stdlib.h>
#include <sys/stat.h>

struct cs_etm_recording {
        struct auxtrace_record  itr;
        struct perf_pmu         *cs_etm_pmu;
        struct perf_evlist      *evlist;
        int                     wrapped_cnt;
        bool                    *wrapped;
        bool                    snapshot_mode;
        size_t                  snapshot_size;
};

static const char *metadata_etmv3_ro[CS_ETM_PRIV_MAX] = {
        [CS_ETM_ETMCCER]        = "mgmt/etmccer",
        [CS_ETM_ETMIDR]         = "mgmt/etmidr",
};

static const char *metadata_etmv4_ro[CS_ETMV4_PRIV_MAX] = {
        [CS_ETMV4_TRCIDR0]              = "trcidr/trcidr0",
        [CS_ETMV4_TRCIDR1]              = "trcidr/trcidr1",
        [CS_ETMV4_TRCIDR2]              = "trcidr/trcidr2",
        [CS_ETMV4_TRCIDR8]              = "trcidr/trcidr8",
        [CS_ETMV4_TRCAUTHSTATUS]        = "mgmt/trcauthstatus",
};

static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu);

static int cs_etm_set_context_id(struct auxtrace_record *itr,
                                 struct perf_evsel *evsel, int cpu)
{
        struct cs_etm_recording *ptr;
        struct perf_pmu *cs_etm_pmu;
        char path[PATH_MAX];
        int err = -EINVAL;
        u32 val;

        ptr = container_of(itr, struct cs_etm_recording, itr);
        cs_etm_pmu = ptr->cs_etm_pmu;

        if (!cs_etm_is_etmv4(itr, cpu))
                goto out;

        /* Get a handle on TRCIRD2 */
        snprintf(path, PATH_MAX, "cpu%d/%s",
                 cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR2]);
        err = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);

        /* There was a problem reading the file, bailing out */
        if (err != 1) {
                pr_err("%s: can't read file %s\n",
                       CORESIGHT_ETM_PMU_NAME, path);
                goto out;
        }

        /*
         * TRCIDR2.CIDSIZE, bit [9-5], indicates whether contextID tracing
         * is supported:
         *  0b00000 Context ID tracing is not supported.
         *  0b00100 Maximum of 32-bit Context ID size.
         *  All other values are reserved.
         */
        val = BMVAL(val, 5, 9);
        if (!val || val != 0x4) {
                err = -EINVAL;
                goto out;
        }

        /* All good, let the kernel know */
        evsel->attr.config |= (1 << ETM_OPT_CTXTID);
        err = 0;

out:

        return err;
}

static int cs_etm_set_timestamp(struct auxtrace_record *itr,
                                struct perf_evsel *evsel, int cpu)
{
        struct cs_etm_recording *ptr;
        struct perf_pmu *cs_etm_pmu;
        char path[PATH_MAX];
        int err = -EINVAL;
        u32 val;

        ptr = container_of(itr, struct cs_etm_recording, itr);
        cs_etm_pmu = ptr->cs_etm_pmu;

        if (!cs_etm_is_etmv4(itr, cpu))
                goto out;

        /* Get a handle on TRCIRD0 */
        snprintf(path, PATH_MAX, "cpu%d/%s",
                 cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
        err = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);

        /* There was a problem reading the file, bailing out */
        if (err != 1) {
                pr_err("%s: can't read file %s\n",
                       CORESIGHT_ETM_PMU_NAME, path);
                goto out;
        }

        /*
         * TRCIDR0.TSSIZE, bit [28-24], indicates whether global timestamping
         * is supported:
         *  0b00000 Global timestamping is not implemented
         *  0b00110 Implementation supports a maximum timestamp of 48bits.
         *  0b01000 Implementation supports a maximum timestamp of 64bits.
         */
        val &= GENMASK(28, 24);
        if (!val) {
                err = -EINVAL;
                goto out;
        }

        /* All good, let the kernel know */
        evsel->attr.config |= (1 << ETM_OPT_TS);
        err = 0;

out:
        return err;
}

static int cs_etm_set_option(struct auxtrace_record *itr,
                             struct perf_evsel *evsel, u32 option)
{
        int i, err = -EINVAL;
        struct cpu_map *event_cpus = evsel->evlist->cpus;
        struct cpu_map *online_cpus = cpu_map__new(NULL);

        /* Set option of each CPU we have */
        for (i = 0; i < cpu__max_cpu(); i++) {
                if (!cpu_map__has(event_cpus, i) ||
                    !cpu_map__has(online_cpus, i))
                        continue;

                if (option & ETM_OPT_CTXTID) {
                        err = cs_etm_set_context_id(itr, evsel, i);
                        if (err)
                                goto out;
                }
                if (option & ETM_OPT_TS) {
                        err = cs_etm_set_timestamp(itr, evsel, i);
                        if (err)
                                goto out;
                }
                if (option & ~(ETM_OPT_CTXTID | ETM_OPT_TS))
                        /* Nothing else is currently supported */
                        goto out;
        }

        err = 0;
out:
        cpu_map__put(online_cpus);
        return err;
}

static int cs_etm_parse_snapshot_options(struct auxtrace_record *itr,
                                         struct record_opts *opts,
                                         const char *str)
{
        struct cs_etm_recording *ptr =
                                container_of(itr, struct cs_etm_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;
}

static int cs_etm_set_sink_attr(struct perf_pmu *pmu,
                                struct perf_evsel *evsel)
{
        char msg[BUFSIZ], path[PATH_MAX], *sink;
        struct perf_evsel_config_term *term;
        int ret = -EINVAL;
        u32 hash;

        if (evsel->attr.config2 & GENMASK(31, 0))
                return 0;

        list_for_each_entry(term, &evsel->config_terms, list) {
                if (term->type != PERF_EVSEL__CONFIG_TERM_DRV_CFG)
                        continue;

                sink = term->val.drv_cfg;
                snprintf(path, PATH_MAX, "sinks/%s", sink);

                ret = perf_pmu__scan_file(pmu, path, "%x", &hash);
                if (ret != 1) {
                        pr_err("failed to set sink \"%s\" on event %s with %d (%s)\n",
                               sink, perf_evsel__name(evsel), errno,
                               str_error_r(errno, msg, sizeof(msg)));
                        return ret;
                }

                evsel->attr.config2 |= hash;
                return 0;
        }

        /*
         * No sink was provided on the command line - for _now_ treat
         * this as an error.
         */
        return ret;
}

static int cs_etm_recording_options(struct auxtrace_record *itr,
                                    struct perf_evlist *evlist,
                                    struct record_opts *opts)
{
        int ret;
        struct cs_etm_recording *ptr =
                                container_of(itr, struct cs_etm_recording, itr);
        struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
        struct perf_evsel *evsel, *cs_etm_evsel = NULL;
        struct cpu_map *cpus = evlist->cpus;
        bool privileged = (geteuid() == 0 || perf_event_paranoid() < 0);
        int err = 0;

        ptr->evlist = evlist;
        ptr->snapshot_mode = opts->auxtrace_snapshot_mode;

        if (perf_can_record_switch_events())
                opts->record_switch_events = true;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->attr.type == cs_etm_pmu->type) {
                        if (cs_etm_evsel) {
                                pr_err("There may be only one %s event\n",
                                       CORESIGHT_ETM_PMU_NAME);
                                return -EINVAL;
                        }
                        evsel->attr.freq = 0;
                        evsel->attr.sample_period = 1;
                        cs_etm_evsel = evsel;
                        opts->full_auxtrace = true;
                }
        }

        /* no need to continue if at least one event of interest was found */
        if (!cs_etm_evsel)
                return 0;

        ret = cs_etm_set_sink_attr(cs_etm_pmu, cs_etm_evsel);
        if (ret)
                return ret;

        if (opts->use_clockid) {
                pr_err("Cannot use clockid (-k option) with %s\n",
                       CORESIGHT_ETM_PMU_NAME);
                return -EINVAL;
        }

        /* we are in snapshot mode */
        if (opts->auxtrace_snapshot_mode) {
                /*
                 * No size were given to '-S' or '-m,', so go with
                 * the default
                 */
                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;
                }

                /*
                 * '-m,xyz' was specified but no snapshot size, so make the
                 * snapshot size as big as the auxtrace mmap area.
                 */
                if (!opts->auxtrace_snapshot_size) {
                        opts->auxtrace_snapshot_size =
                                opts->auxtrace_mmap_pages * (size_t)page_size;
                }

                /*
                 * -Sxyz was specified but no auxtrace mmap area, so make the
                 * auxtrace mmap area big enough to fit the requested snapshot
                 * 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);
                }

                /* Snapshost size can't be bigger than the auxtrace area */
                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;
                }

                /* Something went wrong somewhere - this shouldn't happen */
                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;
                }
        }

        /* We are in full trace mode but '-m,xyz' wasn't specified */
        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 provided by user */
        if (opts->auxtrace_mmap_pages) {
                unsigned int max_page = (KiB(128) / page_size);
                size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;

                if (!privileged &&
                    opts->auxtrace_mmap_pages > max_page) {
                        opts->auxtrace_mmap_pages = max_page;
                        pr_err("auxtrace too big, truncating to %d\n",
                               max_page);
                }

                if (!is_power_of_2(sz)) {
                        pr_err("Invalid mmap size for %s: must be a power of 2\n",
                               CORESIGHT_ETM_PMU_NAME);
                        return -EINVAL;
                }
        }

        if (opts->auxtrace_snapshot_mode)
                pr_debug2("%s snapshot size: %zu\n", CORESIGHT_ETM_PMU_NAME,
                          opts->auxtrace_snapshot_size);

        /*
         * To obtain the auxtrace buffer file descriptor, the auxtrace
         * event must come first.
         */
        perf_evlist__to_front(evlist, cs_etm_evsel);

        /*
         * In the case of per-cpu mmaps, we need the CPU on the
         * AUX event.  We also need the contextID in order to be notified
         * when a context switch happened.
         */
        if (!cpu_map__empty(cpus)) {
                perf_evsel__set_sample_bit(cs_etm_evsel, CPU);

                err = cs_etm_set_option(itr, cs_etm_evsel,
                                        ETM_OPT_CTXTID | ETM_OPT_TS);
                if (err)
                        goto out;
        }

        /* Add dummy event to keep tracking */
        if (opts->full_auxtrace) {
                struct perf_evsel *tracking_evsel;

                err = parse_events(evlist, "dummy:u", NULL);
                if (err)
                        goto out;

                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);
        }

out:
        return err;
}

static u64 cs_etm_get_config(struct auxtrace_record *itr)
{
        u64 config = 0;
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
        struct perf_evlist *evlist = ptr->evlist;
        struct perf_evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->attr.type == cs_etm_pmu->type) {
                        /*
                         * Variable perf_event_attr::config is assigned to
                         * ETMv3/PTM.  The bit fields have been made to match
                         * the ETMv3.5 ETRMCR register specification.  See the
                         * PMU_FORMAT_ATTR() declarations in
                         * drivers/hwtracing/coresight/coresight-perf.c for
                         * details.
                         */
                        config = evsel->attr.config;
                        break;
                }
        }

        return config;
}

#ifndef BIT
#define BIT(N) (1UL << (N))
#endif

static u64 cs_etmv4_get_config(struct auxtrace_record *itr)
{
        u64 config = 0;
        u64 config_opts = 0;

        /*
         * The perf event variable config bits represent both
         * the command line options and register programming
         * bits in ETMv3/PTM. For ETMv4 we must remap options
         * to real bits
         */
        config_opts = cs_etm_get_config(itr);
        if (config_opts & BIT(ETM_OPT_CYCACC))
                config |= BIT(ETM4_CFG_BIT_CYCACC);
        if (config_opts & BIT(ETM_OPT_CTXTID))
                config |= BIT(ETM4_CFG_BIT_CTXTID);
        if (config_opts & BIT(ETM_OPT_TS))
                config |= BIT(ETM4_CFG_BIT_TS);
        if (config_opts & BIT(ETM_OPT_RETSTK))
                config |= BIT(ETM4_CFG_BIT_RETSTK);

        return config;
}

static size_t
cs_etm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
                      struct perf_evlist *evlist __maybe_unused)
{
        int i;
        int etmv3 = 0, etmv4 = 0;
        struct cpu_map *event_cpus = evlist->cpus;
        struct cpu_map *online_cpus = cpu_map__new(NULL);

        /* cpu map is not empty, we have specific CPUs to work with */
        if (!cpu_map__empty(event_cpus)) {
                for (i = 0; i < cpu__max_cpu(); i++) {
                        if (!cpu_map__has(event_cpus, i) ||
                            !cpu_map__has(online_cpus, i))
                                continue;

                        if (cs_etm_is_etmv4(itr, i))
                                etmv4++;
                        else
                                etmv3++;
                }
        } else {
                /* get configuration for all CPUs in the system */
                for (i = 0; i < cpu__max_cpu(); i++) {
                        if (!cpu_map__has(online_cpus, i))
                                continue;

                        if (cs_etm_is_etmv4(itr, i))
                                etmv4++;
                        else
                                etmv3++;
                }
        }

        cpu_map__put(online_cpus);

        return (CS_ETM_HEADER_SIZE +
               (etmv4 * CS_ETMV4_PRIV_SIZE) +
               (etmv3 * CS_ETMV3_PRIV_SIZE));
}

static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu)
{
        bool ret = false;
        char path[PATH_MAX];
        int scan;
        unsigned int val;
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;

        /* Take any of the RO files for ETMv4 and see if it present */
        snprintf(path, PATH_MAX, "cpu%d/%s",
                 cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
        scan = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);

        /* The file was read successfully, we have a winner */
        if (scan == 1)
                ret = true;

        return ret;
}

static int cs_etm_get_ro(struct perf_pmu *pmu, int cpu, const char *path)
{
        char pmu_path[PATH_MAX];
        int scan;
        unsigned int val = 0;

        /* Get RO metadata from sysfs */
        snprintf(pmu_path, PATH_MAX, "cpu%d/%s", cpu, path);

        scan = perf_pmu__scan_file(pmu, pmu_path, "%x", &val);
        if (scan != 1)
                pr_err("%s: error reading: %s\n", __func__, pmu_path);

        return val;
}

static void cs_etm_get_metadata(int cpu, u32 *offset,
                                struct auxtrace_record *itr,
                                struct auxtrace_info_event *info)
{
        u32 increment;
        u64 magic;
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;

        /* first see what kind of tracer this cpu is affined to */
        if (cs_etm_is_etmv4(itr, cpu)) {
                magic = __perf_cs_etmv4_magic;
                /* Get trace configuration register */
                info->priv[*offset + CS_ETMV4_TRCCONFIGR] =
                                                cs_etmv4_get_config(itr);
                /* Get traceID from the framework */
                info->priv[*offset + CS_ETMV4_TRCTRACEIDR] =
                                                coresight_get_trace_id(cpu);
                /* Get read-only information from sysFS */
                info->priv[*offset + CS_ETMV4_TRCIDR0] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
                info->priv[*offset + CS_ETMV4_TRCIDR1] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv4_ro[CS_ETMV4_TRCIDR1]);
                info->priv[*offset + CS_ETMV4_TRCIDR2] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv4_ro[CS_ETMV4_TRCIDR2]);
                info->priv[*offset + CS_ETMV4_TRCIDR8] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv4_ro[CS_ETMV4_TRCIDR8]);
                info->priv[*offset + CS_ETMV4_TRCAUTHSTATUS] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv4_ro
                                      [CS_ETMV4_TRCAUTHSTATUS]);

                /* How much space was used */
                increment = CS_ETMV4_PRIV_MAX;
        } else {
                magic = __perf_cs_etmv3_magic;
                /* Get configuration register */
                info->priv[*offset + CS_ETM_ETMCR] = cs_etm_get_config(itr);
                /* Get traceID from the framework */
                info->priv[*offset + CS_ETM_ETMTRACEIDR] =
                                                coresight_get_trace_id(cpu);
                /* Get read-only information from sysFS */
                info->priv[*offset + CS_ETM_ETMCCER] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv3_ro[CS_ETM_ETMCCER]);
                info->priv[*offset + CS_ETM_ETMIDR] =
                        cs_etm_get_ro(cs_etm_pmu, cpu,
                                      metadata_etmv3_ro[CS_ETM_ETMIDR]);

                /* How much space was used */
                increment = CS_ETM_PRIV_MAX;
        }

        /* Build generic header portion */
        info->priv[*offset + CS_ETM_MAGIC] = magic;
        info->priv[*offset + CS_ETM_CPU] = cpu;
        /* Where the next CPU entry should start from */
        *offset += increment;
}

static int cs_etm_info_fill(struct auxtrace_record *itr,
                            struct perf_session *session,
                            struct auxtrace_info_event *info,
                            size_t priv_size)
{
        int i;
        u32 offset;
        u64 nr_cpu, type;
        struct cpu_map *cpu_map;
        struct cpu_map *event_cpus = session->evlist->cpus;
        struct cpu_map *online_cpus = cpu_map__new(NULL);
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;

        if (priv_size != cs_etm_info_priv_size(itr, session->evlist))
                return -EINVAL;

        if (!session->evlist->nr_mmaps)
                return -EINVAL;

        /* If the cpu_map is empty all online CPUs are involved */
        if (cpu_map__empty(event_cpus)) {
                cpu_map = online_cpus;
        } else {
                /* Make sure all specified CPUs are online */
                for (i = 0; i < cpu_map__nr(event_cpus); i++) {
                        if (cpu_map__has(event_cpus, i) &&
                            !cpu_map__has(online_cpus, i))
                                return -EINVAL;
                }

                cpu_map = event_cpus;
        }

        nr_cpu = cpu_map__nr(cpu_map);
        /* Get PMU type as dynamically assigned by the core */
        type = cs_etm_pmu->type;

        /* First fill out the session header */
        info->type = PERF_AUXTRACE_CS_ETM;
        info->priv[CS_HEADER_VERSION_0] = 0;
        info->priv[CS_PMU_TYPE_CPUS] = type << 32;
        info->priv[CS_PMU_TYPE_CPUS] |= nr_cpu;
        info->priv[CS_ETM_SNAPSHOT] = ptr->snapshot_mode;

        offset = CS_ETM_SNAPSHOT + 1;

        for (i = 0; i < cpu__max_cpu() && offset < priv_size; i++)
                if (cpu_map__has(cpu_map, i))
                        cs_etm_get_metadata(i, &offset, itr, info);

        cpu_map__put(online_cpus);

        return 0;
}

static int cs_etm_alloc_wrapped_array(struct cs_etm_recording *ptr, int idx)
{
        bool *wrapped;
        int cnt = ptr->wrapped_cnt;

        /* Make @ptr->wrapped as big as @idx */
        while (cnt <= idx)
                cnt++;

        /*
         * Free'ed in cs_etm_recording_free().  Using realloc() to avoid
         * cross compilation problems where the host's system supports
         * reallocarray() but not the target.
         */
        wrapped = realloc(ptr->wrapped, cnt * sizeof(bool));
        if (!wrapped)
                return -ENOMEM;

        wrapped[cnt - 1] = false;
        ptr->wrapped_cnt = cnt;
        ptr->wrapped = wrapped;

        return 0;
}

static bool cs_etm_buffer_has_wrapped(unsigned char *buffer,
                                      size_t buffer_size, u64 head)
{
        u64 i, watermark;
        u64 *buf = (u64 *)buffer;
        size_t buf_size = buffer_size;

        /*
         * We want to look the very last 512 byte (chosen arbitrarily) in
         * the ring buffer.
         */
        watermark = buf_size - 512;

        /*
         * @head is continuously increasing - if its value is equal or greater
         * than the size of the ring buffer, it has wrapped around.
         */
        if (head >= buffer_size)
                return true;

        /*
         * The value of @head is somewhere within the size of the ring buffer.
         * This can be that there hasn't been enough data to fill the ring
         * buffer yet or the trace time was so long that @head has numerically
         * wrapped around.  To find we need to check if we have data at the very
         * end of the ring buffer.  We can reliably do this because mmap'ed
         * pages are zeroed out and there is a fresh mapping with every new
         * session.
         */

        /* @head is less than 512 byte from the end of the ring buffer */
        if (head > watermark)
                watermark = head;

        /*
         * Speed things up by using 64 bit transactions (see "u64 *buf" above)
         */
        watermark >>= 3;
        buf_size >>= 3;

        /*
         * If we find trace data at the end of the ring buffer, @head has
         * been there and has numerically wrapped around at least once.
         */
        for (i = watermark; i < buf_size; i++)
                if (buf[i])
                        return true;

        return false;
}

static int cs_etm_find_snapshot(struct auxtrace_record *itr,
                                int idx, struct auxtrace_mmap *mm,
                                unsigned char *data,
                                u64 *head, u64 *old)
{
        int err;
        bool wrapped;
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);

        /*
         * Allocate memory to keep track of wrapping if this is the first
         * time we deal with this *mm.
         */
        if (idx >= ptr->wrapped_cnt) {
                err = cs_etm_alloc_wrapped_array(ptr, idx);
                if (err)
                        return err;
        }

        /*
         * Check to see if *head has wrapped around.  If it hasn't only the
         * amount of data between *head and *old is snapshot'ed to avoid
         * bloating the perf.data file with zeros.  But as soon as *head has
         * wrapped around the entire size of the AUX ring buffer it taken.
         */
        wrapped = ptr->wrapped[idx];
        if (!wrapped && cs_etm_buffer_has_wrapped(data, mm->len, *head)) {
                wrapped = true;
                ptr->wrapped[idx] = true;
        }

        pr_debug3("%s: mmap index %d old head %zu new head %zu size %zu\n",
                  __func__, idx, (size_t)*old, (size_t)*head, mm->len);

        /* No wrap has occurred, we can just use *head and *old. */
        if (!wrapped)
                return 0;

        /*
         * *head has wrapped around - adjust *head and *old to pickup the
         * entire content of the AUX buffer.
         */
        if (*head >= mm->len) {
                *old = *head - mm->len;
        } else {
                *head += mm->len;
                *old = *head - mm->len;
        }

        return 0;
}

static int cs_etm_snapshot_start(struct auxtrace_record *itr)
{
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_evsel *evsel;

        evlist__for_each_entry(ptr->evlist, evsel) {
                if (evsel->attr.type == ptr->cs_etm_pmu->type)
                        return perf_evsel__disable(evsel);
        }
        return -EINVAL;
}

static int cs_etm_snapshot_finish(struct auxtrace_record *itr)
{
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_evsel *evsel;

        evlist__for_each_entry(ptr->evlist, evsel) {
                if (evsel->attr.type == ptr->cs_etm_pmu->type)
                        return perf_evsel__enable(evsel);
        }
        return -EINVAL;
}

static u64 cs_etm_reference(struct auxtrace_record *itr __maybe_unused)
{
        return (((u64) rand() <<  0) & 0x00000000FFFFFFFFull) |
                (((u64) rand() << 32) & 0xFFFFFFFF00000000ull);
}

static void cs_etm_recording_free(struct auxtrace_record *itr)
{
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);

        zfree(&ptr->wrapped);
        free(ptr);
}

static int cs_etm_read_finish(struct auxtrace_record *itr, int idx)
{
        struct cs_etm_recording *ptr =
                        container_of(itr, struct cs_etm_recording, itr);
        struct perf_evsel *evsel;

        evlist__for_each_entry(ptr->evlist, evsel) {
                if (evsel->attr.type == ptr->cs_etm_pmu->type)
                        return perf_evlist__enable_event_idx(ptr->evlist,
                                                             evsel, idx);
        }

        return -EINVAL;
}

struct auxtrace_record *cs_etm_record_init(int *err)
{
        struct perf_pmu *cs_etm_pmu;
        struct cs_etm_recording *ptr;

        cs_etm_pmu = perf_pmu__find(CORESIGHT_ETM_PMU_NAME);

        if (!cs_etm_pmu) {
                *err = -EINVAL;
                goto out;
        }

        ptr = zalloc(sizeof(struct cs_etm_recording));
        if (!ptr) {
                *err = -ENOMEM;
                goto out;
        }

        ptr->cs_etm_pmu                 = cs_etm_pmu;
        ptr->itr.parse_snapshot_options = cs_etm_parse_snapshot_options;
        ptr->itr.recording_options      = cs_etm_recording_options;
        ptr->itr.info_priv_size         = cs_etm_info_priv_size;
        ptr->itr.info_fill              = cs_etm_info_fill;
        ptr->itr.find_snapshot          = cs_etm_find_snapshot;
        ptr->itr.snapshot_start         = cs_etm_snapshot_start;
        ptr->itr.snapshot_finish        = cs_etm_snapshot_finish;
        ptr->itr.reference              = cs_etm_reference;
        ptr->itr.free                   = cs_etm_recording_free;
        ptr->itr.read_finish            = cs_etm_read_finish;

        *err = 0;
        return &ptr->itr;
out:
        return NULL;
}