probe-file.c

Go to the documentation of this file.

/*
 * probe-file.c : operate ftrace k/uprobe events files
 *
 * Written by Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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 <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include "util.h"
#include "event.h"
#include "strlist.h"
#include "strfilter.h"
#include "debug.h"
#include "cache.h"
#include "color.h"
#include "symbol.h"
#include "thread.h"
#include <api/fs/tracing_path.h>
#include "probe-event.h"
#include "probe-file.h"
#include "session.h"
#include "perf_regs.h"
#include "string2.h"

/* 4096 - 2 ('\n' + '\0') */
#define MAX_CMDLEN 4094

static void print_open_warning(int err, bool uprobe)
{
    char sbuf[STRERR_BUFSIZE];

    if (err == -ENOENT) {
        const char *config;

        if (uprobe)
            config = "CONFIG_UPROBE_EVENTS";
        else
            config = "CONFIG_KPROBE_EVENTS";

        pr_warning("%cprobe_events file does not exist"
               " - please rebuild kernel with %s.\n",
               uprobe ? 'u' : 'k', config);
    } else if (err == -ENOTSUP)
        pr_warning("Tracefs or debugfs is not mounted.\n");
    else
        pr_warning("Failed to open %cprobe_events: %s\n",
               uprobe ? 'u' : 'k',
               str_error_r(-err, sbuf, sizeof(sbuf)));
}

static void print_both_open_warning(int kerr, int uerr)
{
    /* Both kprobes and uprobes are disabled, warn it. */
    if (kerr == -ENOTSUP && uerr == -ENOTSUP)
        pr_warning("Tracefs or debugfs is not mounted.\n");
    else if (kerr == -ENOENT && uerr == -ENOENT)
        pr_warning("Please rebuild kernel with CONFIG_KPROBE_EVENTS "
               "or/and CONFIG_UPROBE_EVENTS.\n");
    else {
        char sbuf[STRERR_BUFSIZE];
        pr_warning("Failed to open kprobe events: %s.\n",
               str_error_r(-kerr, sbuf, sizeof(sbuf)));
        pr_warning("Failed to open uprobe events: %s.\n",
               str_error_r(-uerr, sbuf, sizeof(sbuf)));
    }
}

int open_trace_file(const char *trace_file, bool readwrite)
{
    char buf[PATH_MAX];
    int ret;

    ret = e_snprintf(buf, PATH_MAX, "%s/%s", tracing_path_mount(), trace_file);
    if (ret >= 0) {
        pr_debug("Opening %s write=%d\n", buf, readwrite);
        if (readwrite && !probe_event_dry_run)
            ret = open(buf, O_RDWR | O_APPEND, 0);
        else
            ret = open(buf, O_RDONLY, 0);

        if (ret < 0)
            ret = -errno;
    }
    return ret;
}

static int open_kprobe_events(bool readwrite)
{
    return open_trace_file("kprobe_events", readwrite);
}

static int open_uprobe_events(bool readwrite)
{
    return open_trace_file("uprobe_events", readwrite);
}

int probe_file__open(int flag)
{
    int fd;

    if (flag & PF_FL_UPROBE)
        fd = open_uprobe_events(flag & PF_FL_RW);
    else
        fd = open_kprobe_events(flag & PF_FL_RW);
    if (fd < 0)
        print_open_warning(fd, flag & PF_FL_UPROBE);

    return fd;
}

int probe_file__open_both(int *kfd, int *ufd, int flag)
{
    if (!kfd || !ufd)
        return -EINVAL;

    *kfd = open_kprobe_events(flag & PF_FL_RW);
    *ufd = open_uprobe_events(flag & PF_FL_RW);
    if (*kfd < 0 && *ufd < 0) {
        print_both_open_warning(*kfd, *ufd);
        return *kfd;
    }

    return 0;
}

/* Get raw string list of current kprobe_events  or uprobe_events */
struct strlist *probe_file__get_rawlist(int fd)
{
    int ret, idx, fddup;
    FILE *fp;
    char buf[MAX_CMDLEN];
    char *p;
    struct strlist *sl;

    if (fd < 0)
        return NULL;

    sl = strlist__new(NULL, NULL);
    if (sl == NULL)
        return NULL;

    fddup = dup(fd);
    if (fddup < 0)
        goto out_free_sl;

    fp = fdopen(fddup, "r");
    if (!fp)
        goto out_close_fddup;

    while (!feof(fp)) {
        p = fgets(buf, MAX_CMDLEN, fp);
        if (!p)
            break;

        idx = strlen(p) - 1;
        if (p[idx] == '\n')
            p[idx] = '\0';
        ret = strlist__add(sl, buf);
        if (ret < 0) {
            pr_debug("strlist__add failed (%d)\n", ret);
            goto out_close_fp;
        }
    }
    fclose(fp);

    return sl;

out_close_fp:
    fclose(fp);
    goto out_free_sl;
out_close_fddup:
    close(fddup);
out_free_sl:
    strlist__delete(sl);
    return NULL;
}

static struct strlist *__probe_file__get_namelist(int fd, bool include_group)
{
    char buf[128];
    struct strlist *sl, *rawlist;
    struct str_node *ent;
    struct probe_trace_event tev;
    int ret = 0;

    memset(&tev, 0, sizeof(tev));
    rawlist = probe_file__get_rawlist(fd);
    if (!rawlist)
        return NULL;
    sl = strlist__new(NULL, NULL);
    strlist__for_each_entry(ent, rawlist) {
        ret = parse_probe_trace_command(ent->s, &tev);
        if (ret < 0)
            break;
        if (include_group) {
            ret = e_snprintf(buf, 128, "%s:%s", tev.group,
                    tev.event);
            if (ret >= 0)
                ret = strlist__add(sl, buf);
        } else
            ret = strlist__add(sl, tev.event);
        clear_probe_trace_event(&tev);
        if (ret < 0)
            break;
    }
    strlist__delete(rawlist);

    if (ret < 0) {
        strlist__delete(sl);
        return NULL;
    }
    return sl;
}

/* Get current perf-probe event names */
struct strlist *probe_file__get_namelist(int fd)
{
    return __probe_file__get_namelist(fd, false);
}

int probe_file__add_event(int fd, struct probe_trace_event *tev)
{
    int ret = 0;
    char *buf = synthesize_probe_trace_command(tev);
    char sbuf[STRERR_BUFSIZE];

    if (!buf) {
        pr_debug("Failed to synthesize probe trace event.\n");
        return -EINVAL;
    }

    pr_debug("Writing event: %s\n", buf);
    if (!probe_event_dry_run) {
        if (write(fd, buf, strlen(buf)) < (int)strlen(buf)) {
            ret = -errno;
            pr_warning("Failed to write event: %s\n",
                   str_error_r(errno, sbuf, sizeof(sbuf)));
        }
    }
    free(buf);

    return ret;
}

static int __del_trace_probe_event(int fd, struct str_node *ent)
{
    char *p;
    char buf[128];
    int ret;

    /* Convert from perf-probe event to trace-probe event */
    ret = e_snprintf(buf, 128, "-:%s", ent->s);
    if (ret < 0)
        goto error;

    p = strchr(buf + 2, ':');
    if (!p) {
        pr_debug("Internal error: %s should have ':' but not.\n",
             ent->s);
        ret = -ENOTSUP;
        goto error;
    }
    *p = '/';

    pr_debug("Writing event: %s\n", buf);
    ret = write(fd, buf, strlen(buf));
    if (ret < 0) {
        ret = -errno;
        goto error;
    }

    return 0;
error:
    pr_warning("Failed to delete event: %s\n",
           str_error_r(-ret, buf, sizeof(buf)));
    return ret;
}

int probe_file__get_events(int fd, struct strfilter *filter,
               struct strlist *plist)
{
    struct strlist *namelist;
    struct str_node *ent;
    const char *p;
    int ret = -ENOENT;

    if (!plist)
        return -EINVAL;

    namelist = __probe_file__get_namelist(fd, true);
    if (!namelist)
        return -ENOENT;

    strlist__for_each_entry(ent, namelist) {
        p = strchr(ent->s, ':');
        if ((p && strfilter__compare(filter, p + 1)) ||
            strfilter__compare(filter, ent->s)) {
            strlist__add(plist, ent->s);
            ret = 0;
        }
    }
    strlist__delete(namelist);

    return ret;
}

int probe_file__del_strlist(int fd, struct strlist *namelist)
{
    int ret = 0;
    struct str_node *ent;

    strlist__for_each_entry(ent, namelist) {
        ret = __del_trace_probe_event(fd, ent);
        if (ret < 0)
            break;
    }
    return ret;
}

int probe_file__del_events(int fd, struct strfilter *filter)
{
    struct strlist *namelist;
    int ret;

    namelist = strlist__new(NULL, NULL);
    if (!namelist)
        return -ENOMEM;

    ret = probe_file__get_events(fd, filter, namelist);
    if (ret < 0)
        return ret;

    ret = probe_file__del_strlist(fd, namelist);
    strlist__delete(namelist);

    return ret;
}

/* Caller must ensure to remove this entry from list */
static void probe_cache_entry__delete(struct probe_cache_entry *entry)
{
    if (entry) {
        BUG_ON(!list_empty(&entry->node));

        strlist__delete(entry->tevlist);
        clear_perf_probe_event(&entry->pev);
        zfree(&entry->spev);
        free(entry);
    }
}

static struct probe_cache_entry *
probe_cache_entry__new(struct perf_probe_event *pev)
{
    struct probe_cache_entry *entry = zalloc(sizeof(*entry));

    if (entry) {
        INIT_LIST_HEAD(&entry->node);
        entry->tevlist = strlist__new(NULL, NULL);
        if (!entry->tevlist)
            zfree(&entry);
        else if (pev) {
            entry->spev = synthesize_perf_probe_command(pev);
            if (!entry->spev ||
                perf_probe_event__copy(&entry->pev, pev) < 0) {
                probe_cache_entry__delete(entry);
                return NULL;
            }
        }
    }

    return entry;
}

int probe_cache_entry__get_event(struct probe_cache_entry *entry,
                 struct probe_trace_event **tevs)
{
    struct probe_trace_event *tev;
    struct str_node *node;
    int ret, i;

    ret = strlist__nr_entries(entry->tevlist);
    if (ret > probe_conf.max_probes)
        return -E2BIG;

    *tevs = zalloc(ret * sizeof(*tev));
    if (!*tevs)
        return -ENOMEM;

    i = 0;
    strlist__for_each_entry(node, entry->tevlist) {
        tev = &(*tevs)[i++];
        ret = parse_probe_trace_command(node->s, tev);
        if (ret < 0)
            break;
    }
    return i;
}

/* For the kernel probe caches, pass target = NULL or DSO__NAME_KALLSYMS */
static int probe_cache__open(struct probe_cache *pcache, const char *target,
                 struct nsinfo *nsi)
{
    char cpath[PATH_MAX];
    char sbuildid[SBUILD_ID_SIZE];
    char *dir_name = NULL;
    bool is_kallsyms = false;
    int ret, fd;
    struct nscookie nsc;

    if (target && build_id_cache__cached(target)) {
        /* This is a cached buildid */
        strncpy(sbuildid, target, SBUILD_ID_SIZE);
        dir_name = build_id_cache__linkname(sbuildid, NULL, 0);
        goto found;
    }

    if (!target || !strcmp(target, DSO__NAME_KALLSYMS)) {
        target = DSO__NAME_KALLSYMS;
        is_kallsyms = true;
        ret = sysfs__sprintf_build_id("/", sbuildid);
    } else {
        nsinfo__mountns_enter(nsi, &nsc);
        ret = filename__sprintf_build_id(target, sbuildid);
        nsinfo__mountns_exit(&nsc);
    }

    if (ret < 0) {
        pr_debug("Failed to get build-id from %s.\n", target);
        return ret;
    }

    /* If we have no buildid cache, make it */
    if (!build_id_cache__cached(sbuildid)) {
        ret = build_id_cache__add_s(sbuildid, target, nsi,
                        is_kallsyms, NULL);
        if (ret < 0) {
            pr_debug("Failed to add build-id cache: %s\n", target);
            return ret;
        }
    }

    dir_name = build_id_cache__cachedir(sbuildid, target, nsi, is_kallsyms,
                        false);
found:
    if (!dir_name) {
        pr_debug("Failed to get cache from %s\n", target);
        return -ENOMEM;
    }

    snprintf(cpath, PATH_MAX, "%s/probes", dir_name);
    fd = open(cpath, O_CREAT | O_RDWR, 0644);
    if (fd < 0)
        pr_debug("Failed to open cache(%d): %s\n", fd, cpath);
    free(dir_name);
    pcache->fd = fd;

    return fd;
}

static int probe_cache__load(struct probe_cache *pcache)
{
    struct probe_cache_entry *entry = NULL;
    char buf[MAX_CMDLEN], *p;
    int ret = 0, fddup;
    FILE *fp;

    fddup = dup(pcache->fd);
    if (fddup < 0)
        return -errno;
    fp = fdopen(fddup, "r");
    if (!fp) {
        close(fddup);
        return -EINVAL;
    }

    while (!feof(fp)) {
        if (!fgets(buf, MAX_CMDLEN, fp))
            break;
        p = strchr(buf, '\n');
        if (p)
            *p = '\0';
        /* #perf_probe_event or %sdt_event */
        if (buf[0] == '#' || buf[0] == '%') {
            entry = probe_cache_entry__new(NULL);
            if (!entry) {
                ret = -ENOMEM;
                goto out;
            }
            if (buf[0] == '%')
                entry->sdt = true;
            entry->spev = strdup(buf + 1);
            if (entry->spev)
                ret = parse_perf_probe_command(buf + 1,
                                &entry->pev);
            else
                ret = -ENOMEM;
            if (ret < 0) {
                probe_cache_entry__delete(entry);
                goto out;
            }
            list_add_tail(&entry->node, &pcache->entries);
        } else {    /* trace_probe_event */
            if (!entry) {
                ret = -EINVAL;
                goto out;
            }
            strlist__add(entry->tevlist, buf);
        }
    }
out:
    fclose(fp);
    return ret;
}

static struct probe_cache *probe_cache__alloc(void)
{
    struct probe_cache *pcache = zalloc(sizeof(*pcache));

    if (pcache) {
        INIT_LIST_HEAD(&pcache->entries);
        pcache->fd = -EINVAL;
    }
    return pcache;
}

void probe_cache__purge(struct probe_cache *pcache)
{
    struct probe_cache_entry *entry, *n;

    list_for_each_entry_safe(entry, n, &pcache->entries, node) {
        list_del_init(&entry->node);
        probe_cache_entry__delete(entry);
    }
}

void probe_cache__delete(struct probe_cache *pcache)
{
    if (!pcache)
        return;

    probe_cache__purge(pcache);
    if (pcache->fd > 0)
        close(pcache->fd);
    free(pcache);
}

struct probe_cache *probe_cache__new(const char *target, struct nsinfo *nsi)
{
    struct probe_cache *pcache = probe_cache__alloc();
    int ret;

    if (!pcache)
        return NULL;

    ret = probe_cache__open(pcache, target, nsi);
    if (ret < 0) {
        pr_debug("Cache open error: %d\n", ret);
        goto out_err;
    }

    ret = probe_cache__load(pcache);
    if (ret < 0) {
        pr_debug("Cache read error: %d\n", ret);
        goto out_err;
    }

    return pcache;

out_err:
    probe_cache__delete(pcache);
    return NULL;
}

static bool streql(const char *a, const char *b)
{
    if (a == b)
        return true;

    if (!a || !b)
        return false;

    return !strcmp(a, b);
}

struct probe_cache_entry *
probe_cache__find(struct probe_cache *pcache, struct perf_probe_event *pev)
{
    struct probe_cache_entry *entry = NULL;
    char *cmd = synthesize_perf_probe_command(pev);

    if (!cmd)
        return NULL;

    for_each_probe_cache_entry(entry, pcache) {
        if (pev->sdt) {
            if (entry->pev.event &&
                streql(entry->pev.event, pev->event) &&
                (!pev->group ||
                 streql(entry->pev.group, pev->group)))
                goto found;

            continue;
        }
        /* Hit if same event name or same command-string */
        if ((pev->event &&
             (streql(entry->pev.group, pev->group) &&
              streql(entry->pev.event, pev->event))) ||
            (!strcmp(entry->spev, cmd)))
            goto found;
    }
    entry = NULL;

found:
    free(cmd);
    return entry;
}

struct probe_cache_entry *
probe_cache__find_by_name(struct probe_cache *pcache,
              const char *group, const char *event)
{
    struct probe_cache_entry *entry = NULL;

    for_each_probe_cache_entry(entry, pcache) {
        /* Hit if same event name or same command-string */
        if (streql(entry->pev.group, group) &&
            streql(entry->pev.event, event))
            goto found;
    }
    entry = NULL;

found:
    return entry;
}

int probe_cache__add_entry(struct probe_cache *pcache,
               struct perf_probe_event *pev,
               struct probe_trace_event *tevs, int ntevs)
{
    struct probe_cache_entry *entry = NULL;
    char *command;
    int i, ret = 0;

    if (!pcache || !pev || !tevs || ntevs <= 0) {
        ret = -EINVAL;
        goto out_err;
    }

    /* Remove old cache entry */
    entry = probe_cache__find(pcache, pev);
    if (entry) {
        list_del_init(&entry->node);
        probe_cache_entry__delete(entry);
    }

    ret = -ENOMEM;
    entry = probe_cache_entry__new(pev);
    if (!entry)
        goto out_err;

    for (i = 0; i < ntevs; i++) {
        if (!tevs[i].point.symbol)
            continue;

        command = synthesize_probe_trace_command(&tevs[i]);
        if (!command)
            goto out_err;
        strlist__add(entry->tevlist, command);
        free(command);
    }
    list_add_tail(&entry->node, &pcache->entries);
    pr_debug("Added probe cache: %d\n", ntevs);
    return 0;

out_err:
    pr_debug("Failed to add probe caches\n");
    probe_cache_entry__delete(entry);
    return ret;
}

#ifdef HAVE_GELF_GETNOTE_SUPPORT
static unsigned long long sdt_note__get_addr(struct sdt_note *note)
{
    return note->bit32 ? (unsigned long long)note->addr.a32[0]
         : (unsigned long long)note->addr.a64[0];
}

static const char * const type_to_suffix[] = {
    ":s64", "", "", "", ":s32", "", ":s16", ":s8",
    "", ":u8", ":u16", "", ":u32", "", "", "", ":u64"
};

/*
 * Isolate the string number and convert it into a decimal value;
 * this will be an index to get suffix of the uprobe name (defining
 * the type)
 */
static int sdt_arg_parse_size(char *n_ptr, const char **suffix)
{
    long type_idx;

    type_idx = strtol(n_ptr, NULL, 10);
    if (type_idx < -8 || type_idx > 8) {
        pr_debug4("Failed to get a valid sdt type\n");
        return -1;
    }

    *suffix = type_to_suffix[type_idx + 8];
    return 0;
}

static int synthesize_sdt_probe_arg(struct strbuf *buf, int i, const char *arg)
{
    char *op, *desc = strdup(arg), *new_op = NULL;
    const char *suffix = "";
    int ret = -1;

    if (desc == NULL) {
        pr_debug4("Allocation error\n");
        return ret;
    }

    /*
     * Argument is in N@OP format. N is size of the argument and OP is
     * the actual assembly operand. N can be omitted; in that case
     * argument is just OP(without @).
     */
    op = strchr(desc, '@');
    if (op) {
        op[0] = '\0';
        op++;

        if (sdt_arg_parse_size(desc, &suffix))
            goto error;
    } else {
        op = desc;
    }

    ret = arch_sdt_arg_parse_op(op, &new_op);

    if (ret < 0)
        goto error;

    if (ret == SDT_ARG_VALID) {
        ret = strbuf_addf(buf, " arg%d=%s%s", i + 1, new_op, suffix);
        if (ret < 0)
            goto error;
    }

    ret = 0;
error:
    free(desc);
    free(new_op);
    return ret;
}

static char *synthesize_sdt_probe_command(struct sdt_note *note,
                    const char *pathname,
                    const char *sdtgrp)
{
    struct strbuf buf;
    char *ret = NULL, **args;
    int i, args_count;

    if (strbuf_init(&buf, 32) < 0)
        return NULL;

    if (strbuf_addf(&buf, "p:%s/%s %s:0x%llx",
                sdtgrp, note->name, pathname,
                sdt_note__get_addr(note)) < 0)
        goto error;

    if (!note->args)
        goto out;

    if (note->args) {
        args = argv_split(note->args, &args_count);

        for (i = 0; i < args_count; ++i) {
            if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0)
                goto error;
        }
    }

out:
    ret = strbuf_detach(&buf, NULL);
error:
    strbuf_release(&buf);
    return ret;
}

int probe_cache__scan_sdt(struct probe_cache *pcache, const char *pathname)
{
    struct probe_cache_entry *entry = NULL;
    struct list_head sdtlist;
    struct sdt_note *note;
    char *buf;
    char sdtgrp[64];
    int ret;

    INIT_LIST_HEAD(&sdtlist);
    ret = get_sdt_note_list(&sdtlist, pathname);
    if (ret < 0) {
        pr_debug4("Failed to get sdt note: %d\n", ret);
        return ret;
    }
    list_for_each_entry(note, &sdtlist, note_list) {
        ret = snprintf(sdtgrp, 64, "sdt_%s", note->provider);
        if (ret < 0)
            break;
        /* Try to find same-name entry */
        entry = probe_cache__find_by_name(pcache, sdtgrp, note->name);
        if (!entry) {
            entry = probe_cache_entry__new(NULL);
            if (!entry) {
                ret = -ENOMEM;
                break;
            }
            entry->sdt = true;
            ret = asprintf(&entry->spev, "%s:%s=%s", sdtgrp,
                    note->name, note->name);
            if (ret < 0)
                break;
            entry->pev.event = strdup(note->name);
            entry->pev.group = strdup(sdtgrp);
            list_add_tail(&entry->node, &pcache->entries);
        }
        buf = synthesize_sdt_probe_command(note, pathname, sdtgrp);
        if (!buf) {
            ret = -ENOMEM;
            break;
        }

        strlist__add(entry->tevlist, buf);
        free(buf);
        entry = NULL;
    }
    if (entry) {
        list_del_init(&entry->node);
        probe_cache_entry__delete(entry);
    }
    cleanup_sdt_note_list(&sdtlist);
    return ret;
}
#endif

static int probe_cache_entry__write(struct probe_cache_entry *entry, int fd)
{
    struct str_node *snode;
    struct stat st;
    struct iovec iov[3];
    const char *prefix = entry->sdt ? "%" : "#";
    int ret;
    /* Save stat for rollback */
    ret = fstat(fd, &st);
    if (ret < 0)
        return ret;

    pr_debug("Writing cache: %s%s\n", prefix, entry->spev);
    iov[0].iov_base = (void *)prefix; iov[0].iov_len = 1;
    iov[1].iov_base = entry->spev; iov[1].iov_len = strlen(entry->spev);
    iov[2].iov_base = (void *)"\n"; iov[2].iov_len = 1;
    ret = writev(fd, iov, 3);
    if (ret < (int)iov[1].iov_len + 2)
        goto rollback;

    strlist__for_each_entry(snode, entry->tevlist) {
        iov[0].iov_base = (void *)snode->s;
        iov[0].iov_len = strlen(snode->s);
        iov[1].iov_base = (void *)"\n"; iov[1].iov_len = 1;
        ret = writev(fd, iov, 2);
        if (ret < (int)iov[0].iov_len + 1)
            goto rollback;
    }
    return 0;

rollback:
    /* Rollback to avoid cache file corruption */
    if (ret > 0)
        ret = -1;
    if (ftruncate(fd, st.st_size) < 0)
        ret = -2;

    return ret;
}

int probe_cache__commit(struct probe_cache *pcache)
{
    struct probe_cache_entry *entry;
    int ret = 0;

    /* TBD: if we do not update existing entries, skip it */
    ret = lseek(pcache->fd, 0, SEEK_SET);
    if (ret < 0)
        goto out;

    ret = ftruncate(pcache->fd, 0);
    if (ret < 0)
        goto out;

    for_each_probe_cache_entry(entry, pcache) {
        ret = probe_cache_entry__write(entry, pcache->fd);
        pr_debug("Cache committed: %d\n", ret);
        if (ret < 0)
            break;
    }
out:
    return ret;
}

static bool probe_cache_entry__compare(struct probe_cache_entry *entry,
                       struct strfilter *filter)
{
    char buf[128], *ptr = entry->spev;

    if (entry->pev.event) {
        snprintf(buf, 128, "%s:%s", entry->pev.group, entry->pev.event);
        ptr = buf;
    }
    return strfilter__compare(filter, ptr);
}

int probe_cache__filter_purge(struct probe_cache *pcache,
                  struct strfilter *filter)
{
    struct probe_cache_entry *entry, *tmp;

    list_for_each_entry_safe(entry, tmp, &pcache->entries, node) {
        if (probe_cache_entry__compare(entry, filter)) {
            pr_info("Removed cached event: %s\n", entry->spev);
            list_del_init(&entry->node);
            probe_cache_entry__delete(entry);
        }
    }
    return 0;
}

static int probe_cache__show_entries(struct probe_cache *pcache,
                     struct strfilter *filter)
{
    struct probe_cache_entry *entry;

    for_each_probe_cache_entry(entry, pcache) {
        if (probe_cache_entry__compare(entry, filter))
            printf("%s\n", entry->spev);
    }
    return 0;
}

/* Show all cached probes */
int probe_cache__show_all_caches(struct strfilter *filter)
{
    struct probe_cache *pcache;
    struct strlist *bidlist;
    struct str_node *nd;
    char *buf = strfilter__string(filter);

    pr_debug("list cache with filter: %s\n", buf);
    free(buf);

    bidlist = build_id_cache__list_all(true);
    if (!bidlist) {
        pr_debug("Failed to get buildids: %d\n", errno);
        return -EINVAL;
    }
    strlist__for_each_entry(nd, bidlist) {
        pcache = probe_cache__new(nd->s, NULL);
        if (!pcache)
            continue;
        if (!list_empty(&pcache->entries)) {
            buf = build_id_cache__origname(nd->s);
            printf("%s (%s):\n", buf, nd->s);
            free(buf);
            probe_cache__show_entries(pcache, filter);
        }
        probe_cache__delete(pcache);
    }
    strlist__delete(bidlist);

    return 0;
}

enum ftrace_readme {
    FTRACE_README_PROBE_TYPE_X = 0,
    FTRACE_README_KRETPROBE_OFFSET,
    FTRACE_README_END,
};

static struct {
    const char *pattern;
    bool avail;
} ftrace_readme_table[] = {
#define DEFINE_TYPE(idx, pat)           \
    [idx] = {.pattern = pat, .avail = false}
    DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
    DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
};

static bool scan_ftrace_readme(enum ftrace_readme type)
{
    int fd;
    FILE *fp;
    char *buf = NULL;
    size_t len = 0;
    bool ret = false;
    static bool scanned = false;

    if (scanned)
        goto result;

    fd = open_trace_file("README", false);
    if (fd < 0)
        return ret;

    fp = fdopen(fd, "r");
    if (!fp) {
        close(fd);
        return ret;
    }

    while (getline(&buf, &len, fp) > 0)
        for (enum ftrace_readme i = 0; i < FTRACE_README_END; i++)
            if (!ftrace_readme_table[i].avail)
                ftrace_readme_table[i].avail =
                    strglobmatch(buf, ftrace_readme_table[i].pattern);
    scanned = true;

    fclose(fp);
    free(buf);

result:
    if (type >= FTRACE_README_END)
        return false;

    return ftrace_readme_table[type].avail;
}

bool probe_type_is_available(enum probe_type type)
{
    if (type >= PROBE_TYPE_END)
        return false;
    else if (type == PROBE_TYPE_X)
        return scan_ftrace_readme(FTRACE_README_PROBE_TYPE_X);

    return true;
}

bool kretprobe_offset_is_supported(void)
{
    return scan_ftrace_readme(FTRACE_README_KRETPROBE_OFFSET);
}