// SPDX-License-Identifier: GPL-2.0
/*
 * event probes
 *
 * Part of this code was copied from kernel/trace/trace_kprobe.c written by
 * Masami Hiramatsu <mhiramat@kernel.org>
 *
 * Copyright (C) 2021, VMware Inc, Steven Rostedt <rostedt@goodmis.org>
 * Copyright (C) 2021, VMware Inc, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
 *
 */
#include <linux/cleanup.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/mutex.h>

#include "trace_dynevent.h"
#include "trace_probe.h"
#include "trace_probe_kernel.h"
#include "trace_probe_tmpl.h"

#define EPROBE_EVENT_SYSTEM "eprobes"

struct trace_eprobe {
        /* tracepoint system */
        const char *event_system;

        /* tracepoint event */
        const char *event_name;

        /* filter string for the tracepoint */
        char *filter_str;

        struct trace_event_call *event;

        struct dyn_event        devent;
        struct trace_probe      tp;
};

struct eprobe_data {
        struct trace_event_file *file;
        struct trace_eprobe     *ep;
};


#define for_each_trace_eprobe_tp(ep, _tp) \
        list_for_each_entry(ep, trace_probe_probe_list(_tp), tp.list)

static int __trace_eprobe_create(int argc, const char *argv[]);

static void trace_event_probe_cleanup(struct trace_eprobe *ep)
{
        if (!ep)
                return;
        trace_probe_cleanup(&ep->tp);
        kfree(ep->event_name);
        kfree(ep->event_system);
        if (ep->event)
                trace_event_put_ref(ep->event);
        kfree(ep->filter_str);
        kfree(ep);
}

DEFINE_FREE(trace_event_probe_cleanup, struct trace_eprobe *,
                if (!IS_ERR_OR_NULL(_T)) trace_event_probe_cleanup(_T))

static struct trace_eprobe *to_trace_eprobe(struct dyn_event *ev)
{
        return container_of(ev, struct trace_eprobe, devent);
}

static int eprobe_dyn_event_create(const char *raw_command)
{
        return trace_probe_create(raw_command, __trace_eprobe_create);
}

static int eprobe_dyn_event_show(struct seq_file *m, struct dyn_event *ev)
{
        struct trace_eprobe *ep = to_trace_eprobe(ev);
        int i;

        seq_printf(m, "e:%s/%s", trace_probe_group_name(&ep->tp),
                                trace_probe_name(&ep->tp));
        seq_printf(m, " %s.%s", ep->event_system, ep->event_name);

        for (i = 0; i < ep->tp.nr_args; i++)
                seq_printf(m, " %s=%s", ep->tp.args[i].name, ep->tp.args[i].comm);
        seq_putc(m, '\n');

        return 0;
}

static int unregister_trace_eprobe(struct trace_eprobe *ep)
{
        /* If other probes are on the event, just unregister eprobe */
        if (trace_probe_has_sibling(&ep->tp))
                goto unreg;

        /* Enabled event can not be unregistered */
        if (trace_probe_is_enabled(&ep->tp))
                return -EBUSY;

        /* Will fail if probe is being used by ftrace or perf */
        if (trace_probe_unregister_event_call(&ep->tp))
                return -EBUSY;

unreg:
        dyn_event_remove(&ep->devent);
        trace_probe_unlink(&ep->tp);

        return 0;
}

static int eprobe_dyn_event_release(struct dyn_event *ev)
{
        struct trace_eprobe *ep = to_trace_eprobe(ev);
        int ret = unregister_trace_eprobe(ep);

        if (!ret)
                trace_event_probe_cleanup(ep);
        return ret;
}

static bool eprobe_dyn_event_is_busy(struct dyn_event *ev)
{
        struct trace_eprobe *ep = to_trace_eprobe(ev);

        return trace_probe_is_enabled(&ep->tp);
}

static bool eprobe_dyn_event_match(const char *system, const char *event,
                        int argc, const char **argv, struct dyn_event *ev)
{
        struct trace_eprobe *ep = to_trace_eprobe(ev);
        const char *slash;

        /*
         * We match the following:
         *  event only                  - match all eprobes with event name
         *  system and event only       - match all system/event probes
         *  system only                 - match all system probes
         *
         * The below has the above satisfied with more arguments:
         *
         *  attached system/event       - If the arg has the system and event
         *                                the probe is attached to, match
         *                                probes with the attachment.
         *
         *  If any more args are given, then it requires a full match.
         */

        /*
         * If system exists, but this probe is not part of that system
         * do not match.
         */
        if (system && strcmp(trace_probe_group_name(&ep->tp), system) != 0)
                return false;

        /* Must match the event name */
        if (event[0] != '\0' && strcmp(trace_probe_name(&ep->tp), event) != 0)
                return false;

        /* No arguments match all */
        if (argc < 1)
                return true;

        /* First argument is the system/event the probe is attached to */

        slash = strchr(argv[0], '/');
        if (!slash)
                slash = strchr(argv[0], '.');
        if (!slash)
                return false;

        if (strncmp(ep->event_system, argv[0], slash - argv[0]))
                return false;
        if (strcmp(ep->event_name, slash + 1))
                return false;

        argc--;
        argv++;

        /* If there are no other args, then match */
        if (argc < 1)
                return true;

        return trace_probe_match_command_args(&ep->tp, argc, argv);
}

static struct dyn_event_operations eprobe_dyn_event_ops = {
        .create = eprobe_dyn_event_create,
        .show = eprobe_dyn_event_show,
        .is_busy = eprobe_dyn_event_is_busy,
        .free = eprobe_dyn_event_release,
        .match = eprobe_dyn_event_match,
};

static struct trace_eprobe *alloc_event_probe(const char *group,
                                              const char *this_event,
                                              struct trace_event_call *event,
                                              int nargs)
{
        struct trace_eprobe *ep __free(trace_event_probe_cleanup) = NULL;
        const char *event_name;
        const char *sys_name;
        int ret;

        if (!event)
                return ERR_PTR(-ENODEV);

        sys_name = event->class->system;
        event_name = trace_event_name(event);

        ep = kzalloc_flex(*ep, tp.args, nargs);
        if (!ep) {
                trace_event_put_ref(event);
                return ERR_PTR(-ENOMEM);
        }
        ep->event = event;
        ep->event_name = kstrdup(event_name, GFP_KERNEL);
        if (!ep->event_name)
                return ERR_PTR(-ENOMEM);
        ep->event_system = kstrdup(sys_name, GFP_KERNEL);
        if (!ep->event_system)
                return ERR_PTR(-ENOMEM);

        ret = trace_probe_init(&ep->tp, this_event, group, false, nargs);
        if (ret < 0)
                return ERR_PTR(ret);

        dyn_event_init(&ep->devent, &eprobe_dyn_event_ops);
        return_ptr(ep);
}

static int eprobe_event_define_fields(struct trace_event_call *event_call)
{
        struct eprobe_trace_entry_head field;
        struct trace_probe *tp;

        tp = trace_probe_primary_from_call(event_call);
        if (WARN_ON_ONCE(!tp))
                return -ENOENT;

        return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
}

static struct trace_event_fields eprobe_fields_array[] = {
        { .type = TRACE_FUNCTION_TYPE,
          .define_fields = eprobe_event_define_fields },
        {}
};

/* Event entry printers */
static enum print_line_t
print_eprobe_event(struct trace_iterator *iter, int flags,
                   struct trace_event *event)
{
        struct eprobe_trace_entry_head *field;
        struct trace_event_call *pevent;
        struct trace_event *probed_event;
        struct trace_seq *s = &iter->seq;
        struct trace_eprobe *ep;
        struct trace_probe *tp;
        unsigned int type;

        field = (struct eprobe_trace_entry_head *)iter->ent;
        tp = trace_probe_primary_from_call(
                container_of(event, struct trace_event_call, event));
        if (WARN_ON_ONCE(!tp))
                goto out;

        ep = container_of(tp, struct trace_eprobe, tp);
        type = ep->event->event.type;

        trace_seq_printf(s, "%s: (", trace_probe_name(tp));

        probed_event = ftrace_find_event(type);
        if (probed_event) {
                pevent = container_of(probed_event, struct trace_event_call, event);
                trace_seq_printf(s, "%s.%s", pevent->class->system,
                                 trace_event_name(pevent));
        } else {
                trace_seq_printf(s, "%u", type);
        }

        trace_seq_putc(s, ')');

        if (trace_probe_print_args(s, tp->args, tp->nr_args,
                             (u8 *)&field[1], field) < 0)
                goto out;

        trace_seq_putc(s, '\n');
 out:
        return trace_handle_return(s);
}

static nokprobe_inline unsigned long
get_event_field(struct fetch_insn *code, void *rec)
{
        struct ftrace_event_field *field = code->data;
        unsigned long val;
        void *addr;

        addr = rec + field->offset;

        if (is_string_field(field)) {
                switch (field->filter_type) {
                case FILTER_DYN_STRING:
                        val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
                        break;
                case FILTER_RDYN_STRING:
                        val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
                        break;
                case FILTER_STATIC_STRING:
                        val = (unsigned long)addr;
                        break;
                case FILTER_PTR_STRING:
                        val = (unsigned long)(*(char *)addr);
                        break;
                default:
                        WARN_ON_ONCE(1);
                        return 0;
                }
                return val;
        }

        switch (field->size) {
        case 1:
                if (field->is_signed)
                        val = *(char *)addr;
                else
                        val = *(unsigned char *)addr;
                break;
        case 2:
                if (field->is_signed)
                        val = *(short *)addr;
                else
                        val = *(unsigned short *)addr;
                break;
        case 4:
                if (field->is_signed)
                        val = *(int *)addr;
                else
                        val = *(unsigned int *)addr;
                break;
        default:
                if (field->size == sizeof(long)) {
                        if (field->is_signed)
                                val = *(long *)addr;
                        else
                                val = *(unsigned long *)addr;
                        break;
                }
                /* This is an array, point to the addr itself */
                val = (unsigned long)addr;
                break;
        }
        return val;
}

static int get_eprobe_size(struct trace_probe *tp, void *rec)
{
        struct fetch_insn *code;
        struct probe_arg *arg;
        int i, len, ret = 0;

        for (i = 0; i < tp->nr_args; i++) {
                arg = tp->args + i;
                if (arg->dynamic) {
                        unsigned long val;

                        code = arg->code;
 retry:
                        switch (code->op) {
                        case FETCH_OP_TP_ARG:
                                val = get_event_field(code, rec);
                                break;
                        case FETCH_NOP_SYMBOL:  /* Ignore a place holder */
                                code++;
                                goto retry;
                        default:
                                if (process_common_fetch_insn(code, &val) < 0)
                                        continue;
                        }
                        code++;
                        len = process_fetch_insn_bottom(code, val, NULL, NULL);
                        if (len > 0)
                                ret += len;
                }
        }

        return ret;
}

/* Kprobe specific fetch functions */

/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
                   void *dest, void *base)
{
        unsigned long val;
        int ret;

 retry:
        switch (code->op) {
        case FETCH_OP_TP_ARG:
                val = get_event_field(code, rec);
                break;
        case FETCH_NOP_SYMBOL:  /* Ignore a place holder */
                code++;
                goto retry;
        default:
                ret = process_common_fetch_insn(code, &val);
                if (ret < 0)
                        return ret;
        }
        code++;
        return process_fetch_insn_bottom(code, val, dest, base);
}
NOKPROBE_SYMBOL(process_fetch_insn)

/* eprobe handler */
static inline void
__eprobe_trace_func(struct eprobe_data *edata, void *rec)
{
        struct eprobe_trace_entry_head *entry;
        struct trace_event_call *call = trace_probe_event_call(&edata->ep->tp);
        struct trace_event_buffer fbuffer;
        int dsize;

        if (WARN_ON_ONCE(call != edata->file->event_call))
                return;

        if (trace_trigger_soft_disabled(edata->file))
                return;

        dsize = get_eprobe_size(&edata->ep->tp, rec);

        entry = trace_event_buffer_reserve(&fbuffer, edata->file,
                                           sizeof(*entry) + edata->ep->tp.size + dsize);

        if (!entry)
                return;

        entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
        store_trace_args(&entry[1], &edata->ep->tp, rec, NULL, sizeof(*entry), dsize);

        trace_event_buffer_commit(&fbuffer);
}

/*
 * The event probe implementation uses event triggers to get access to
 * the event it is attached to, but is not an actual trigger. The below
 * functions are just stubs to fulfill what is needed to use the trigger
 * infrastructure.
 */
static int eprobe_trigger_init(struct event_trigger_data *data)
{
        return 0;
}

static void eprobe_trigger_free(struct event_trigger_data *data)
{

}

static int eprobe_trigger_print(struct seq_file *m,
                                struct event_trigger_data *data)
{
        /* Do not print eprobe event triggers */
        return 0;
}

static void eprobe_trigger_func(struct event_trigger_data *data,
                                struct trace_buffer *buffer, void *rec,
                                struct ring_buffer_event *rbe)
{
        struct eprobe_data *edata = data->private_data;

        if (unlikely(!rec))
                return;

        __eprobe_trace_func(edata, rec);
}

static int eprobe_trigger_cmd_parse(struct event_command *cmd_ops,
                                    struct trace_event_file *file,
                                    char *glob, char *cmd,
                                    char *param_and_filter)
{
        return -1;
}

static int eprobe_trigger_reg_func(char *glob,
                                   struct event_trigger_data *data,
                                   struct trace_event_file *file)
{
        return -1;
}

static void eprobe_trigger_unreg_func(char *glob,
                                      struct event_trigger_data *data,
                                      struct trace_event_file *file)
{

}

static struct event_command event_trigger_cmd = {
        .name                   = "eprobe",
        .trigger_type           = ETT_EVENT_EPROBE,
        .flags                  = EVENT_CMD_FL_NEEDS_REC,
        .parse                  = eprobe_trigger_cmd_parse,
        .reg                    = eprobe_trigger_reg_func,
        .unreg                  = eprobe_trigger_unreg_func,
        .unreg_all              = NULL,
        .set_filter             = NULL,
        .trigger                = eprobe_trigger_func,
        .print                  = eprobe_trigger_print,
        .init                   = eprobe_trigger_init,
        .free                   = eprobe_trigger_free,
};

static struct event_trigger_data *
new_eprobe_trigger(struct trace_eprobe *ep, struct trace_event_file *file)
{
        struct event_trigger_data *trigger;
        struct event_filter *filter = NULL;
        struct eprobe_data *edata;
        int ret;

        edata = kzalloc_obj(*edata);
        trigger = kzalloc_obj(*trigger);
        if (!trigger || !edata) {
                ret = -ENOMEM;
                goto error;
        }

        trigger->flags = EVENT_TRIGGER_FL_PROBE;
        trigger->count = -1;

        /*
         * EVENT PROBE triggers are not registered as commands with
         * register_event_command(), as they are not controlled by the user
         * from the trigger file
         */
        trigger->cmd_ops = &event_trigger_cmd;

        INIT_LIST_HEAD(&trigger->list);

        if (ep->filter_str) {
                ret = create_event_filter(file->tr, ep->event,
                                        ep->filter_str, false, &filter);
                if (ret)
                        goto error;
        }
        RCU_INIT_POINTER(trigger->filter, filter);

        edata->file = file;
        edata->ep = ep;
        trigger->private_data = edata;

        return trigger;
error:
        free_event_filter(filter);
        kfree(edata);
        kfree(trigger);
        return ERR_PTR(ret);
}

static int enable_eprobe(struct trace_eprobe *ep,
                         struct trace_event_file *eprobe_file)
{
        struct event_trigger_data *trigger;
        struct trace_event_file *file;
        struct trace_array *tr = eprobe_file->tr;

        file = find_event_file(tr, ep->event_system, ep->event_name);
        if (!file)
                return -ENOENT;
        trigger = new_eprobe_trigger(ep, eprobe_file);
        if (IS_ERR(trigger))
                return PTR_ERR(trigger);

        list_add_tail_rcu(&trigger->list, &file->triggers);

        trace_event_trigger_enable_disable(file, 1);
        update_cond_flag(file);

        return 0;
}

static struct trace_event_functions eprobe_funcs = {
        .trace          = print_eprobe_event
};

static int disable_eprobe(struct trace_eprobe *ep,
                          struct trace_array *tr)
{
        struct event_trigger_data *trigger = NULL, *iter;
        struct trace_event_file *file;
        struct event_filter *filter;
        struct eprobe_data *edata;

        file = find_event_file(tr, ep->event_system, ep->event_name);
        if (!file)
                return -ENOENT;

        list_for_each_entry(iter, &file->triggers, list) {
                if (!(iter->flags & EVENT_TRIGGER_FL_PROBE))
                        continue;
                edata = iter->private_data;
                if (edata->ep == ep) {
                        trigger = iter;
                        break;
                }
        }
        if (!trigger)
                return -ENODEV;

        list_del_rcu(&trigger->list);

        trace_event_trigger_enable_disable(file, 0);
        update_cond_flag(file);

        /* Make sure nothing is using the edata or trigger */
        tracepoint_synchronize_unregister();

        filter = rcu_access_pointer(trigger->filter);

        if (filter)
                free_event_filter(filter);
        kfree(edata);
        kfree(trigger);

        return 0;
}

static int enable_trace_eprobe(struct trace_event_call *call,
                               struct trace_event_file *file)
{
        struct trace_probe *tp;
        struct trace_eprobe *ep;
        bool enabled;
        int ret = 0;
        int cnt = 0;

        tp = trace_probe_primary_from_call(call);
        if (WARN_ON_ONCE(!tp))
                return -ENODEV;
        enabled = trace_probe_is_enabled(tp);

        /* This also changes "enabled" state */
        if (file) {
                ret = trace_probe_add_file(tp, file);
                if (ret)
                        return ret;
        } else
                trace_probe_set_flag(tp, TP_FLAG_PROFILE);

        if (enabled)
                return 0;

        for_each_trace_eprobe_tp(ep, tp) {
                ret = enable_eprobe(ep, file);
                if (ret)
                        break;
                enabled = true;
                cnt++;
        }

        if (ret) {
                /* Failed to enable one of them. Roll back all */
                if (enabled) {
                        /*
                         * It's a bug if one failed for something other than memory
                         * not being available but another eprobe succeeded.
                         */
                        WARN_ON_ONCE(ret != -ENOMEM);

                        for_each_trace_eprobe_tp(ep, tp) {
                                disable_eprobe(ep, file->tr);
                                if (!--cnt)
                                        break;
                        }
                }
                if (file)
                        trace_probe_remove_file(tp, file);
                else
                        trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
        }

        return ret;
}

static int disable_trace_eprobe(struct trace_event_call *call,
                                struct trace_event_file *file)
{
        struct trace_probe *tp;
        struct trace_eprobe *ep;

        tp = trace_probe_primary_from_call(call);
        if (WARN_ON_ONCE(!tp))
                return -ENODEV;

        if (file) {
                if (!trace_probe_get_file_link(tp, file))
                        return -ENOENT;
                if (!trace_probe_has_single_file(tp))
                        goto out;
                trace_probe_clear_flag(tp, TP_FLAG_TRACE);
        } else
                trace_probe_clear_flag(tp, TP_FLAG_PROFILE);

        if (!trace_probe_is_enabled(tp)) {
                for_each_trace_eprobe_tp(ep, tp)
                        disable_eprobe(ep, file->tr);
        }

 out:
        if (file)
                /*
                 * Synchronization is done in below function. For perf event,
                 * file == NULL and perf_trace_event_unreg() calls
                 * tracepoint_synchronize_unregister() to ensure synchronize
                 * event. We don't need to care about it.
                 */
                trace_probe_remove_file(tp, file);

        return 0;
}

static int eprobe_register(struct trace_event_call *event,
                           enum trace_reg type, void *data)
{
        struct trace_event_file *file = data;

        switch (type) {
        case TRACE_REG_REGISTER:
                return enable_trace_eprobe(event, file);
        case TRACE_REG_UNREGISTER:
                return disable_trace_eprobe(event, file);
#ifdef CONFIG_PERF_EVENTS
        case TRACE_REG_PERF_REGISTER:
        case TRACE_REG_PERF_UNREGISTER:
        case TRACE_REG_PERF_OPEN:
        case TRACE_REG_PERF_CLOSE:
        case TRACE_REG_PERF_ADD:
        case TRACE_REG_PERF_DEL:
                return 0;
#endif
        }
        return 0;
}

static inline void init_trace_eprobe_call(struct trace_eprobe *ep)
{
        struct trace_event_call *call = trace_probe_event_call(&ep->tp);

        call->flags = TRACE_EVENT_FL_EPROBE;
        call->event.funcs = &eprobe_funcs;
        call->class->fields_array = eprobe_fields_array;
        call->class->reg = eprobe_register;
}

static struct trace_event_call *
find_and_get_event(const char *system, const char *event_name)
{
        struct trace_event_call *tp_event;
        const char *name;

        list_for_each_entry(tp_event, &ftrace_events, list) {
                /* Skip other probes and ftrace events */
                if (tp_event->flags &
                    (TRACE_EVENT_FL_IGNORE_ENABLE |
                     TRACE_EVENT_FL_KPROBE |
                     TRACE_EVENT_FL_UPROBE |
                     TRACE_EVENT_FL_EPROBE))
                        continue;
                if (!tp_event->class->system ||
                    strcmp(system, tp_event->class->system))
                        continue;
                name = trace_event_name(tp_event);
                if (!name || strcmp(event_name, name))
                        continue;
                if (!trace_event_try_get_ref(tp_event))
                        return NULL;
                return tp_event;
        }
        return NULL;
}

static int trace_eprobe_parse_filter(struct trace_eprobe *ep, int argc, const char *argv[])
{
        struct event_filter *dummy = NULL;
        int i, ret, len = 0;
        char *p;

        if (argc == 0) {
                trace_probe_log_err(0, NO_EP_FILTER);
                return -EINVAL;
        }

        /* Recover the filter string */
        for (i = 0; i < argc; i++)
                len += strlen(argv[i]) + 1;

        ep->filter_str = kzalloc(len, GFP_KERNEL);
        if (!ep->filter_str)
                return -ENOMEM;

        p = ep->filter_str;
        for (i = 0; i < argc; i++) {
                if (i)
                        ret = snprintf(p, len, " %s", argv[i]);
                else
                        ret = snprintf(p, len, "%s", argv[i]);
                p += ret;
                len -= ret;
        }

        /*
         * Ensure the filter string can be parsed correctly. Note, this
         * filter string is for the original event, not for the eprobe.
         */
        ret = create_event_filter(top_trace_array(), ep->event, ep->filter_str,
                                  true, &dummy);
        free_event_filter(dummy);
        if (ret) {
                kfree(ep->filter_str);
                ep->filter_str = NULL;
        }
        return ret;
}

static int __trace_eprobe_create(int argc, const char *argv[])
{
        /*
         * Argument syntax:
         *      e[:[GRP/][ENAME]] SYSTEM.EVENT [FETCHARGS] [if FILTER]
         * Fetch args (no space):
         *  <name>=$<field>[:TYPE]
         */
        struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) = NULL;
        struct trace_eprobe *ep __free(trace_event_probe_cleanup) = NULL;
        const char *trlog __free(trace_probe_log_clear) = NULL;
        const char *event = NULL, *group = EPROBE_EVENT_SYSTEM;
        const char *sys_event = NULL, *sys_name = NULL;
        struct trace_event_call *event_call;
        char *buf1 __free(kfree) = NULL;
        char *buf2 __free(kfree) = NULL;
        char *gbuf __free(kfree) = NULL;
        int ret = 0, filter_idx = 0;
        int i, filter_cnt;

        if (argc < 2 || argv[0][0] != 'e')
                return -ECANCELED;

        trlog = trace_probe_log_init("event_probe", argc, argv);

        event = strchr(&argv[0][1], ':');
        if (event) {
                gbuf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
                if (!gbuf)
                        return -ENOMEM;
                event++;
                ret = traceprobe_parse_event_name(&event, &group, gbuf,
                                                  event - argv[0]);
                if (ret)
                        return -EINVAL;
        }

        trace_probe_log_set_index(1);
        sys_event = argv[1];

        buf2 = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
        if (!buf2)
                return -ENOMEM;

        ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
        if (ret || !sys_event || !sys_name) {
                trace_probe_log_err(0, NO_EVENT_INFO);
                return -EINVAL;
        }

        if (!event) {
                buf1 = kstrdup(sys_event, GFP_KERNEL);
                if (!buf1)
                        return -ENOMEM;
                event = buf1;
        }

        for (i = 2; i < argc; i++) {
                if (!strcmp(argv[i], "if")) {
                        filter_idx = i + 1;
                        filter_cnt = argc - filter_idx;
                        argc = i;
                        break;
                }
        }

        if (argc - 2 > MAX_TRACE_ARGS) {
                trace_probe_log_set_index(2);
                trace_probe_log_err(0, TOO_MANY_ARGS);
                return -E2BIG;
        }

        scoped_guard(mutex, &event_mutex) {
                event_call = find_and_get_event(sys_name, sys_event);
                ep = alloc_event_probe(group, event, event_call, argc - 2);
        }

        if (IS_ERR(ep)) {
                ret = PTR_ERR(ep);
                if (ret == -ENODEV)
                        trace_probe_log_err(0, BAD_ATTACH_EVENT);
                /* This must return -ENOMEM or missing event, else there is a bug */
                WARN_ON_ONCE(ret != -ENOMEM && ret != -ENODEV);
                return ret;
        }

        if (filter_idx) {
                trace_probe_log_set_index(filter_idx);
                ret = trace_eprobe_parse_filter(ep, filter_cnt, argv + filter_idx);
                if (ret)
                        return -EINVAL;
        } else
                ep->filter_str = NULL;

        ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;
        ctx->event = ep->event;
        ctx->flags = TPARG_FL_KERNEL | TPARG_FL_TEVENT;

        argc -= 2; argv += 2;
        /* parse arguments */
        for (i = 0; i < argc; i++) {
                trace_probe_log_set_index(i + 2);

                ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], ctx);
                /* Handle symbols "@" */
                if (!ret)
                        ret = traceprobe_update_arg(&ep->tp.args[i]);
                if (ret)
                        return ret;
        }
        ret = traceprobe_set_print_fmt(&ep->tp, PROBE_PRINT_EVENT);
        if (ret < 0)
                return ret;

        init_trace_eprobe_call(ep);
        scoped_guard(mutex, &event_mutex) {
                ret = trace_probe_register_event_call(&ep->tp);
                if (ret) {
                        if (ret == -EEXIST) {
                                trace_probe_log_set_index(0);
                                trace_probe_log_err(0, EVENT_EXIST);
                        }
                        return ret;
                }
                ret = dyn_event_add(&ep->devent, &ep->tp.event->call);
                if (ret < 0) {
                        trace_probe_unregister_event_call(&ep->tp);
                        return ret;
                }
                /* To avoid freeing registered eprobe event, clear ep. */
                ep = NULL;
        }
        return ret;
}

/*
 * Register dynevent at core_initcall. This allows kernel to setup eprobe
 * events in postcore_initcall without tracefs.
 */
static __init int trace_events_eprobe_init_early(void)
{
        int err = 0;

        err = dyn_event_register(&eprobe_dyn_event_ops);
        if (err)
                pr_warn("Could not register eprobe_dyn_event_ops\n");

        return err;
}
core_initcall(trace_events_eprobe_init_early);