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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * trace_events_synth - synthetic trace events
0004  *
0005  * Copyright (C) 2015, 2020 Tom Zanussi <tom.zanussi@linux.intel.com>
0006  */
0007 
0008 #include <linux/module.h>
0009 #include <linux/kallsyms.h>
0010 #include <linux/security.h>
0011 #include <linux/mutex.h>
0012 #include <linux/slab.h>
0013 #include <linux/stacktrace.h>
0014 #include <linux/rculist.h>
0015 #include <linux/tracefs.h>
0016 
0017 /* for gfp flag names */
0018 #include <linux/trace_events.h>
0019 #include <trace/events/mmflags.h>
0020 
0021 #include "trace_synth.h"
0022 
0023 #undef ERRORS
0024 #define ERRORS  \
0025     C(BAD_NAME,     "Illegal name"),        \
0026     C(INVALID_CMD,      "Command must be of the form: <name> field[;field] ..."),\
0027     C(INVALID_DYN_CMD,  "Command must be of the form: s or -:[synthetic/]<name> field[;field] ..."),\
0028     C(EVENT_EXISTS,     "Event already exists"),    \
0029     C(TOO_MANY_FIELDS,  "Too many fields"),     \
0030     C(INCOMPLETE_TYPE,  "Incomplete type"),     \
0031     C(INVALID_TYPE,     "Invalid type"),        \
0032     C(INVALID_FIELD,        "Invalid field"),       \
0033     C(INVALID_ARRAY_SPEC,   "Invalid array specification"),
0034 
0035 #undef C
0036 #define C(a, b)     SYNTH_ERR_##a
0037 
0038 enum { ERRORS };
0039 
0040 #undef C
0041 #define C(a, b)     b
0042 
0043 static const char *err_text[] = { ERRORS };
0044 
0045 static char *last_cmd;
0046 
0047 static int errpos(const char *str)
0048 {
0049     if (!str || !last_cmd)
0050         return 0;
0051 
0052     return err_pos(last_cmd, str);
0053 }
0054 
0055 static void last_cmd_set(const char *str)
0056 {
0057     if (!str)
0058         return;
0059 
0060     kfree(last_cmd);
0061 
0062     last_cmd = kstrdup(str, GFP_KERNEL);
0063 }
0064 
0065 static void synth_err(u8 err_type, u16 err_pos)
0066 {
0067     if (!last_cmd)
0068         return;
0069 
0070     tracing_log_err(NULL, "synthetic_events", last_cmd, err_text,
0071             err_type, err_pos);
0072 }
0073 
0074 static int create_synth_event(const char *raw_command);
0075 static int synth_event_show(struct seq_file *m, struct dyn_event *ev);
0076 static int synth_event_release(struct dyn_event *ev);
0077 static bool synth_event_is_busy(struct dyn_event *ev);
0078 static bool synth_event_match(const char *system, const char *event,
0079             int argc, const char **argv, struct dyn_event *ev);
0080 
0081 static struct dyn_event_operations synth_event_ops = {
0082     .create = create_synth_event,
0083     .show = synth_event_show,
0084     .is_busy = synth_event_is_busy,
0085     .free = synth_event_release,
0086     .match = synth_event_match,
0087 };
0088 
0089 static bool is_synth_event(struct dyn_event *ev)
0090 {
0091     return ev->ops == &synth_event_ops;
0092 }
0093 
0094 static struct synth_event *to_synth_event(struct dyn_event *ev)
0095 {
0096     return container_of(ev, struct synth_event, devent);
0097 }
0098 
0099 static bool synth_event_is_busy(struct dyn_event *ev)
0100 {
0101     struct synth_event *event = to_synth_event(ev);
0102 
0103     return event->ref != 0;
0104 }
0105 
0106 static bool synth_event_match(const char *system, const char *event,
0107             int argc, const char **argv, struct dyn_event *ev)
0108 {
0109     struct synth_event *sev = to_synth_event(ev);
0110 
0111     return strcmp(sev->name, event) == 0 &&
0112         (!system || strcmp(system, SYNTH_SYSTEM) == 0);
0113 }
0114 
0115 struct synth_trace_event {
0116     struct trace_entry  ent;
0117     u64         fields[];
0118 };
0119 
0120 static int synth_event_define_fields(struct trace_event_call *call)
0121 {
0122     struct synth_trace_event trace;
0123     int offset = offsetof(typeof(trace), fields);
0124     struct synth_event *event = call->data;
0125     unsigned int i, size, n_u64;
0126     char *name, *type;
0127     bool is_signed;
0128     int ret = 0;
0129 
0130     for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
0131         size = event->fields[i]->size;
0132         is_signed = event->fields[i]->is_signed;
0133         type = event->fields[i]->type;
0134         name = event->fields[i]->name;
0135         ret = trace_define_field(call, type, name, offset, size,
0136                      is_signed, FILTER_OTHER);
0137         if (ret)
0138             break;
0139 
0140         event->fields[i]->offset = n_u64;
0141 
0142         if (event->fields[i]->is_string && !event->fields[i]->is_dynamic) {
0143             offset += STR_VAR_LEN_MAX;
0144             n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
0145         } else {
0146             offset += sizeof(u64);
0147             n_u64++;
0148         }
0149     }
0150 
0151     event->n_u64 = n_u64;
0152 
0153     return ret;
0154 }
0155 
0156 static bool synth_field_signed(char *type)
0157 {
0158     if (str_has_prefix(type, "u"))
0159         return false;
0160     if (strcmp(type, "gfp_t") == 0)
0161         return false;
0162 
0163     return true;
0164 }
0165 
0166 static int synth_field_is_string(char *type)
0167 {
0168     if (strstr(type, "char[") != NULL)
0169         return true;
0170 
0171     return false;
0172 }
0173 
0174 static int synth_field_string_size(char *type)
0175 {
0176     char buf[4], *end, *start;
0177     unsigned int len;
0178     int size, err;
0179 
0180     start = strstr(type, "char[");
0181     if (start == NULL)
0182         return -EINVAL;
0183     start += sizeof("char[") - 1;
0184 
0185     end = strchr(type, ']');
0186     if (!end || end < start || type + strlen(type) > end + 1)
0187         return -EINVAL;
0188 
0189     len = end - start;
0190     if (len > 3)
0191         return -EINVAL;
0192 
0193     if (len == 0)
0194         return 0; /* variable-length string */
0195 
0196     strncpy(buf, start, len);
0197     buf[len] = '\0';
0198 
0199     err = kstrtouint(buf, 0, &size);
0200     if (err)
0201         return err;
0202 
0203     if (size > STR_VAR_LEN_MAX)
0204         return -EINVAL;
0205 
0206     return size;
0207 }
0208 
0209 static int synth_field_size(char *type)
0210 {
0211     int size = 0;
0212 
0213     if (strcmp(type, "s64") == 0)
0214         size = sizeof(s64);
0215     else if (strcmp(type, "u64") == 0)
0216         size = sizeof(u64);
0217     else if (strcmp(type, "s32") == 0)
0218         size = sizeof(s32);
0219     else if (strcmp(type, "u32") == 0)
0220         size = sizeof(u32);
0221     else if (strcmp(type, "s16") == 0)
0222         size = sizeof(s16);
0223     else if (strcmp(type, "u16") == 0)
0224         size = sizeof(u16);
0225     else if (strcmp(type, "s8") == 0)
0226         size = sizeof(s8);
0227     else if (strcmp(type, "u8") == 0)
0228         size = sizeof(u8);
0229     else if (strcmp(type, "char") == 0)
0230         size = sizeof(char);
0231     else if (strcmp(type, "unsigned char") == 0)
0232         size = sizeof(unsigned char);
0233     else if (strcmp(type, "int") == 0)
0234         size = sizeof(int);
0235     else if (strcmp(type, "unsigned int") == 0)
0236         size = sizeof(unsigned int);
0237     else if (strcmp(type, "long") == 0)
0238         size = sizeof(long);
0239     else if (strcmp(type, "unsigned long") == 0)
0240         size = sizeof(unsigned long);
0241     else if (strcmp(type, "bool") == 0)
0242         size = sizeof(bool);
0243     else if (strcmp(type, "pid_t") == 0)
0244         size = sizeof(pid_t);
0245     else if (strcmp(type, "gfp_t") == 0)
0246         size = sizeof(gfp_t);
0247     else if (synth_field_is_string(type))
0248         size = synth_field_string_size(type);
0249 
0250     return size;
0251 }
0252 
0253 static const char *synth_field_fmt(char *type)
0254 {
0255     const char *fmt = "%llu";
0256 
0257     if (strcmp(type, "s64") == 0)
0258         fmt = "%lld";
0259     else if (strcmp(type, "u64") == 0)
0260         fmt = "%llu";
0261     else if (strcmp(type, "s32") == 0)
0262         fmt = "%d";
0263     else if (strcmp(type, "u32") == 0)
0264         fmt = "%u";
0265     else if (strcmp(type, "s16") == 0)
0266         fmt = "%d";
0267     else if (strcmp(type, "u16") == 0)
0268         fmt = "%u";
0269     else if (strcmp(type, "s8") == 0)
0270         fmt = "%d";
0271     else if (strcmp(type, "u8") == 0)
0272         fmt = "%u";
0273     else if (strcmp(type, "char") == 0)
0274         fmt = "%d";
0275     else if (strcmp(type, "unsigned char") == 0)
0276         fmt = "%u";
0277     else if (strcmp(type, "int") == 0)
0278         fmt = "%d";
0279     else if (strcmp(type, "unsigned int") == 0)
0280         fmt = "%u";
0281     else if (strcmp(type, "long") == 0)
0282         fmt = "%ld";
0283     else if (strcmp(type, "unsigned long") == 0)
0284         fmt = "%lu";
0285     else if (strcmp(type, "bool") == 0)
0286         fmt = "%d";
0287     else if (strcmp(type, "pid_t") == 0)
0288         fmt = "%d";
0289     else if (strcmp(type, "gfp_t") == 0)
0290         fmt = "%x";
0291     else if (synth_field_is_string(type))
0292         fmt = "%.*s";
0293 
0294     return fmt;
0295 }
0296 
0297 static void print_synth_event_num_val(struct trace_seq *s,
0298                       char *print_fmt, char *name,
0299                       int size, u64 val, char *space)
0300 {
0301     switch (size) {
0302     case 1:
0303         trace_seq_printf(s, print_fmt, name, (u8)val, space);
0304         break;
0305 
0306     case 2:
0307         trace_seq_printf(s, print_fmt, name, (u16)val, space);
0308         break;
0309 
0310     case 4:
0311         trace_seq_printf(s, print_fmt, name, (u32)val, space);
0312         break;
0313 
0314     default:
0315         trace_seq_printf(s, print_fmt, name, val, space);
0316         break;
0317     }
0318 }
0319 
0320 static enum print_line_t print_synth_event(struct trace_iterator *iter,
0321                        int flags,
0322                        struct trace_event *event)
0323 {
0324     struct trace_array *tr = iter->tr;
0325     struct trace_seq *s = &iter->seq;
0326     struct synth_trace_event *entry;
0327     struct synth_event *se;
0328     unsigned int i, n_u64;
0329     char print_fmt[32];
0330     const char *fmt;
0331 
0332     entry = (struct synth_trace_event *)iter->ent;
0333     se = container_of(event, struct synth_event, call.event);
0334 
0335     trace_seq_printf(s, "%s: ", se->name);
0336 
0337     for (i = 0, n_u64 = 0; i < se->n_fields; i++) {
0338         if (trace_seq_has_overflowed(s))
0339             goto end;
0340 
0341         fmt = synth_field_fmt(se->fields[i]->type);
0342 
0343         /* parameter types */
0344         if (tr && tr->trace_flags & TRACE_ITER_VERBOSE)
0345             trace_seq_printf(s, "%s ", fmt);
0346 
0347         snprintf(print_fmt, sizeof(print_fmt), "%%s=%s%%s", fmt);
0348 
0349         /* parameter values */
0350         if (se->fields[i]->is_string) {
0351             if (se->fields[i]->is_dynamic) {
0352                 u32 offset, data_offset;
0353                 char *str_field;
0354 
0355                 offset = (u32)entry->fields[n_u64];
0356                 data_offset = offset & 0xffff;
0357 
0358                 str_field = (char *)entry + data_offset;
0359 
0360                 trace_seq_printf(s, print_fmt, se->fields[i]->name,
0361                          STR_VAR_LEN_MAX,
0362                          str_field,
0363                          i == se->n_fields - 1 ? "" : " ");
0364                 n_u64++;
0365             } else {
0366                 trace_seq_printf(s, print_fmt, se->fields[i]->name,
0367                          STR_VAR_LEN_MAX,
0368                          (char *)&entry->fields[n_u64],
0369                          i == se->n_fields - 1 ? "" : " ");
0370                 n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
0371             }
0372         } else {
0373             struct trace_print_flags __flags[] = {
0374                 __def_gfpflag_names, {-1, NULL} };
0375             char *space = (i == se->n_fields - 1 ? "" : " ");
0376 
0377             print_synth_event_num_val(s, print_fmt,
0378                           se->fields[i]->name,
0379                           se->fields[i]->size,
0380                           entry->fields[n_u64],
0381                           space);
0382 
0383             if (strcmp(se->fields[i]->type, "gfp_t") == 0) {
0384                 trace_seq_puts(s, " (");
0385                 trace_print_flags_seq(s, "|",
0386                               entry->fields[n_u64],
0387                               __flags);
0388                 trace_seq_putc(s, ')');
0389             }
0390             n_u64++;
0391         }
0392     }
0393 end:
0394     trace_seq_putc(s, '\n');
0395 
0396     return trace_handle_return(s);
0397 }
0398 
0399 static struct trace_event_functions synth_event_funcs = {
0400     .trace      = print_synth_event
0401 };
0402 
0403 static unsigned int trace_string(struct synth_trace_event *entry,
0404                  struct synth_event *event,
0405                  char *str_val,
0406                  bool is_dynamic,
0407                  unsigned int data_size,
0408                  unsigned int *n_u64)
0409 {
0410     unsigned int len = 0;
0411     char *str_field;
0412 
0413     if (is_dynamic) {
0414         u32 data_offset;
0415 
0416         data_offset = offsetof(typeof(*entry), fields);
0417         data_offset += event->n_u64 * sizeof(u64);
0418         data_offset += data_size;
0419 
0420         str_field = (char *)entry + data_offset;
0421 
0422         len = strlen(str_val) + 1;
0423         strscpy(str_field, str_val, len);
0424 
0425         data_offset |= len << 16;
0426         *(u32 *)&entry->fields[*n_u64] = data_offset;
0427 
0428         (*n_u64)++;
0429     } else {
0430         str_field = (char *)&entry->fields[*n_u64];
0431 
0432         strscpy(str_field, str_val, STR_VAR_LEN_MAX);
0433         (*n_u64) += STR_VAR_LEN_MAX / sizeof(u64);
0434     }
0435 
0436     return len;
0437 }
0438 
0439 static notrace void trace_event_raw_event_synth(void *__data,
0440                         u64 *var_ref_vals,
0441                         unsigned int *var_ref_idx)
0442 {
0443     unsigned int i, n_u64, val_idx, len, data_size = 0;
0444     struct trace_event_file *trace_file = __data;
0445     struct synth_trace_event *entry;
0446     struct trace_event_buffer fbuffer;
0447     struct trace_buffer *buffer;
0448     struct synth_event *event;
0449     int fields_size = 0;
0450 
0451     event = trace_file->event_call->data;
0452 
0453     if (trace_trigger_soft_disabled(trace_file))
0454         return;
0455 
0456     fields_size = event->n_u64 * sizeof(u64);
0457 
0458     for (i = 0; i < event->n_dynamic_fields; i++) {
0459         unsigned int field_pos = event->dynamic_fields[i]->field_pos;
0460         char *str_val;
0461 
0462         val_idx = var_ref_idx[field_pos];
0463         str_val = (char *)(long)var_ref_vals[val_idx];
0464 
0465         len = strlen(str_val) + 1;
0466 
0467         fields_size += len;
0468     }
0469 
0470     /*
0471      * Avoid ring buffer recursion detection, as this event
0472      * is being performed within another event.
0473      */
0474     buffer = trace_file->tr->array_buffer.buffer;
0475     ring_buffer_nest_start(buffer);
0476 
0477     entry = trace_event_buffer_reserve(&fbuffer, trace_file,
0478                        sizeof(*entry) + fields_size);
0479     if (!entry)
0480         goto out;
0481 
0482     for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
0483         val_idx = var_ref_idx[i];
0484         if (event->fields[i]->is_string) {
0485             char *str_val = (char *)(long)var_ref_vals[val_idx];
0486 
0487             len = trace_string(entry, event, str_val,
0488                        event->fields[i]->is_dynamic,
0489                        data_size, &n_u64);
0490             data_size += len; /* only dynamic string increments */
0491         } else {
0492             struct synth_field *field = event->fields[i];
0493             u64 val = var_ref_vals[val_idx];
0494 
0495             switch (field->size) {
0496             case 1:
0497                 *(u8 *)&entry->fields[n_u64] = (u8)val;
0498                 break;
0499 
0500             case 2:
0501                 *(u16 *)&entry->fields[n_u64] = (u16)val;
0502                 break;
0503 
0504             case 4:
0505                 *(u32 *)&entry->fields[n_u64] = (u32)val;
0506                 break;
0507 
0508             default:
0509                 entry->fields[n_u64] = val;
0510                 break;
0511             }
0512             n_u64++;
0513         }
0514     }
0515 
0516     trace_event_buffer_commit(&fbuffer);
0517 out:
0518     ring_buffer_nest_end(buffer);
0519 }
0520 
0521 static void free_synth_event_print_fmt(struct trace_event_call *call)
0522 {
0523     if (call) {
0524         kfree(call->print_fmt);
0525         call->print_fmt = NULL;
0526     }
0527 }
0528 
0529 static int __set_synth_event_print_fmt(struct synth_event *event,
0530                        char *buf, int len)
0531 {
0532     const char *fmt;
0533     int pos = 0;
0534     int i;
0535 
0536     /* When len=0, we just calculate the needed length */
0537 #define LEN_OR_ZERO (len ? len - pos : 0)
0538 
0539     pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
0540     for (i = 0; i < event->n_fields; i++) {
0541         fmt = synth_field_fmt(event->fields[i]->type);
0542         pos += snprintf(buf + pos, LEN_OR_ZERO, "%s=%s%s",
0543                 event->fields[i]->name, fmt,
0544                 i == event->n_fields - 1 ? "" : ", ");
0545     }
0546     pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
0547 
0548     for (i = 0; i < event->n_fields; i++) {
0549         if (event->fields[i]->is_string &&
0550             event->fields[i]->is_dynamic)
0551             pos += snprintf(buf + pos, LEN_OR_ZERO,
0552                 ", __get_str(%s)", event->fields[i]->name);
0553         else
0554             pos += snprintf(buf + pos, LEN_OR_ZERO,
0555                     ", REC->%s", event->fields[i]->name);
0556     }
0557 
0558 #undef LEN_OR_ZERO
0559 
0560     /* return the length of print_fmt */
0561     return pos;
0562 }
0563 
0564 static int set_synth_event_print_fmt(struct trace_event_call *call)
0565 {
0566     struct synth_event *event = call->data;
0567     char *print_fmt;
0568     int len;
0569 
0570     /* First: called with 0 length to calculate the needed length */
0571     len = __set_synth_event_print_fmt(event, NULL, 0);
0572 
0573     print_fmt = kmalloc(len + 1, GFP_KERNEL);
0574     if (!print_fmt)
0575         return -ENOMEM;
0576 
0577     /* Second: actually write the @print_fmt */
0578     __set_synth_event_print_fmt(event, print_fmt, len + 1);
0579     call->print_fmt = print_fmt;
0580 
0581     return 0;
0582 }
0583 
0584 static void free_synth_field(struct synth_field *field)
0585 {
0586     kfree(field->type);
0587     kfree(field->name);
0588     kfree(field);
0589 }
0590 
0591 static int check_field_version(const char *prefix, const char *field_type,
0592                    const char *field_name)
0593 {
0594     /*
0595      * For backward compatibility, the old synthetic event command
0596      * format did not require semicolons, and in order to not
0597      * break user space, that old format must still work. If a new
0598      * feature is added, then the format that uses the new feature
0599      * will be required to have semicolons, as nothing that uses
0600      * the old format would be using the new, yet to be created,
0601      * feature. When a new feature is added, this will detect it,
0602      * and return a number greater than 1, and require the format
0603      * to use semicolons.
0604      */
0605     return 1;
0606 }
0607 
0608 static struct synth_field *parse_synth_field(int argc, char **argv,
0609                          int *consumed, int *field_version)
0610 {
0611     const char *prefix = NULL, *field_type = argv[0], *field_name, *array;
0612     struct synth_field *field;
0613     int len, ret = -ENOMEM;
0614     struct seq_buf s;
0615     ssize_t size;
0616 
0617     if (!strcmp(field_type, "unsigned")) {
0618         if (argc < 3) {
0619             synth_err(SYNTH_ERR_INCOMPLETE_TYPE, errpos(field_type));
0620             return ERR_PTR(-EINVAL);
0621         }
0622         prefix = "unsigned ";
0623         field_type = argv[1];
0624         field_name = argv[2];
0625         *consumed += 3;
0626     } else {
0627         field_name = argv[1];
0628         *consumed += 2;
0629     }
0630 
0631     if (!field_name) {
0632         synth_err(SYNTH_ERR_INVALID_FIELD, errpos(field_type));
0633         return ERR_PTR(-EINVAL);
0634     }
0635 
0636     *field_version = check_field_version(prefix, field_type, field_name);
0637 
0638     field = kzalloc(sizeof(*field), GFP_KERNEL);
0639     if (!field)
0640         return ERR_PTR(-ENOMEM);
0641 
0642     len = strlen(field_name);
0643     array = strchr(field_name, '[');
0644     if (array)
0645         len -= strlen(array);
0646 
0647     field->name = kmemdup_nul(field_name, len, GFP_KERNEL);
0648     if (!field->name)
0649         goto free;
0650 
0651     if (!is_good_name(field->name)) {
0652         synth_err(SYNTH_ERR_BAD_NAME, errpos(field_name));
0653         ret = -EINVAL;
0654         goto free;
0655     }
0656 
0657     len = strlen(field_type) + 1;
0658 
0659     if (array)
0660         len += strlen(array);
0661 
0662     if (prefix)
0663         len += strlen(prefix);
0664 
0665     field->type = kzalloc(len, GFP_KERNEL);
0666     if (!field->type)
0667         goto free;
0668 
0669     seq_buf_init(&s, field->type, len);
0670     if (prefix)
0671         seq_buf_puts(&s, prefix);
0672     seq_buf_puts(&s, field_type);
0673     if (array)
0674         seq_buf_puts(&s, array);
0675     if (WARN_ON_ONCE(!seq_buf_buffer_left(&s)))
0676         goto free;
0677 
0678     s.buffer[s.len] = '\0';
0679 
0680     size = synth_field_size(field->type);
0681     if (size < 0) {
0682         if (array)
0683             synth_err(SYNTH_ERR_INVALID_ARRAY_SPEC, errpos(field_name));
0684         else
0685             synth_err(SYNTH_ERR_INVALID_TYPE, errpos(field_type));
0686         ret = -EINVAL;
0687         goto free;
0688     } else if (size == 0) {
0689         if (synth_field_is_string(field->type)) {
0690             char *type;
0691 
0692             len = sizeof("__data_loc ") + strlen(field->type) + 1;
0693             type = kzalloc(len, GFP_KERNEL);
0694             if (!type)
0695                 goto free;
0696 
0697             seq_buf_init(&s, type, len);
0698             seq_buf_puts(&s, "__data_loc ");
0699             seq_buf_puts(&s, field->type);
0700 
0701             if (WARN_ON_ONCE(!seq_buf_buffer_left(&s)))
0702                 goto free;
0703             s.buffer[s.len] = '\0';
0704 
0705             kfree(field->type);
0706             field->type = type;
0707 
0708             field->is_dynamic = true;
0709             size = sizeof(u64);
0710         } else {
0711             synth_err(SYNTH_ERR_INVALID_TYPE, errpos(field_type));
0712             ret = -EINVAL;
0713             goto free;
0714         }
0715     }
0716     field->size = size;
0717 
0718     if (synth_field_is_string(field->type))
0719         field->is_string = true;
0720 
0721     field->is_signed = synth_field_signed(field->type);
0722  out:
0723     return field;
0724  free:
0725     free_synth_field(field);
0726     field = ERR_PTR(ret);
0727     goto out;
0728 }
0729 
0730 static void free_synth_tracepoint(struct tracepoint *tp)
0731 {
0732     if (!tp)
0733         return;
0734 
0735     kfree(tp->name);
0736     kfree(tp);
0737 }
0738 
0739 static struct tracepoint *alloc_synth_tracepoint(char *name)
0740 {
0741     struct tracepoint *tp;
0742 
0743     tp = kzalloc(sizeof(*tp), GFP_KERNEL);
0744     if (!tp)
0745         return ERR_PTR(-ENOMEM);
0746 
0747     tp->name = kstrdup(name, GFP_KERNEL);
0748     if (!tp->name) {
0749         kfree(tp);
0750         return ERR_PTR(-ENOMEM);
0751     }
0752 
0753     return tp;
0754 }
0755 
0756 struct synth_event *find_synth_event(const char *name)
0757 {
0758     struct dyn_event *pos;
0759     struct synth_event *event;
0760 
0761     for_each_dyn_event(pos) {
0762         if (!is_synth_event(pos))
0763             continue;
0764         event = to_synth_event(pos);
0765         if (strcmp(event->name, name) == 0)
0766             return event;
0767     }
0768 
0769     return NULL;
0770 }
0771 
0772 static struct trace_event_fields synth_event_fields_array[] = {
0773     { .type = TRACE_FUNCTION_TYPE,
0774       .define_fields = synth_event_define_fields },
0775     {}
0776 };
0777 
0778 static int register_synth_event(struct synth_event *event)
0779 {
0780     struct trace_event_call *call = &event->call;
0781     int ret = 0;
0782 
0783     event->call.class = &event->class;
0784     event->class.system = kstrdup(SYNTH_SYSTEM, GFP_KERNEL);
0785     if (!event->class.system) {
0786         ret = -ENOMEM;
0787         goto out;
0788     }
0789 
0790     event->tp = alloc_synth_tracepoint(event->name);
0791     if (IS_ERR(event->tp)) {
0792         ret = PTR_ERR(event->tp);
0793         event->tp = NULL;
0794         goto out;
0795     }
0796 
0797     INIT_LIST_HEAD(&call->class->fields);
0798     call->event.funcs = &synth_event_funcs;
0799     call->class->fields_array = synth_event_fields_array;
0800 
0801     ret = register_trace_event(&call->event);
0802     if (!ret) {
0803         ret = -ENODEV;
0804         goto out;
0805     }
0806     call->flags = TRACE_EVENT_FL_TRACEPOINT;
0807     call->class->reg = trace_event_reg;
0808     call->class->probe = trace_event_raw_event_synth;
0809     call->data = event;
0810     call->tp = event->tp;
0811 
0812     ret = trace_add_event_call(call);
0813     if (ret) {
0814         pr_warn("Failed to register synthetic event: %s\n",
0815             trace_event_name(call));
0816         goto err;
0817     }
0818 
0819     ret = set_synth_event_print_fmt(call);
0820     if (ret < 0) {
0821         trace_remove_event_call(call);
0822         goto err;
0823     }
0824  out:
0825     return ret;
0826  err:
0827     unregister_trace_event(&call->event);
0828     goto out;
0829 }
0830 
0831 static int unregister_synth_event(struct synth_event *event)
0832 {
0833     struct trace_event_call *call = &event->call;
0834     int ret;
0835 
0836     ret = trace_remove_event_call(call);
0837 
0838     return ret;
0839 }
0840 
0841 static void free_synth_event(struct synth_event *event)
0842 {
0843     unsigned int i;
0844 
0845     if (!event)
0846         return;
0847 
0848     for (i = 0; i < event->n_fields; i++)
0849         free_synth_field(event->fields[i]);
0850 
0851     kfree(event->fields);
0852     kfree(event->dynamic_fields);
0853     kfree(event->name);
0854     kfree(event->class.system);
0855     free_synth_tracepoint(event->tp);
0856     free_synth_event_print_fmt(&event->call);
0857     kfree(event);
0858 }
0859 
0860 static struct synth_event *alloc_synth_event(const char *name, int n_fields,
0861                          struct synth_field **fields)
0862 {
0863     unsigned int i, j, n_dynamic_fields = 0;
0864     struct synth_event *event;
0865 
0866     event = kzalloc(sizeof(*event), GFP_KERNEL);
0867     if (!event) {
0868         event = ERR_PTR(-ENOMEM);
0869         goto out;
0870     }
0871 
0872     event->name = kstrdup(name, GFP_KERNEL);
0873     if (!event->name) {
0874         kfree(event);
0875         event = ERR_PTR(-ENOMEM);
0876         goto out;
0877     }
0878 
0879     event->fields = kcalloc(n_fields, sizeof(*event->fields), GFP_KERNEL);
0880     if (!event->fields) {
0881         free_synth_event(event);
0882         event = ERR_PTR(-ENOMEM);
0883         goto out;
0884     }
0885 
0886     for (i = 0; i < n_fields; i++)
0887         if (fields[i]->is_dynamic)
0888             n_dynamic_fields++;
0889 
0890     if (n_dynamic_fields) {
0891         event->dynamic_fields = kcalloc(n_dynamic_fields,
0892                         sizeof(*event->dynamic_fields),
0893                         GFP_KERNEL);
0894         if (!event->dynamic_fields) {
0895             free_synth_event(event);
0896             event = ERR_PTR(-ENOMEM);
0897             goto out;
0898         }
0899     }
0900 
0901     dyn_event_init(&event->devent, &synth_event_ops);
0902 
0903     for (i = 0, j = 0; i < n_fields; i++) {
0904         fields[i]->field_pos = i;
0905         event->fields[i] = fields[i];
0906 
0907         if (fields[i]->is_dynamic)
0908             event->dynamic_fields[j++] = fields[i];
0909     }
0910     event->n_dynamic_fields = j;
0911     event->n_fields = n_fields;
0912  out:
0913     return event;
0914 }
0915 
0916 static int synth_event_check_arg_fn(void *data)
0917 {
0918     struct dynevent_arg_pair *arg_pair = data;
0919     int size;
0920 
0921     size = synth_field_size((char *)arg_pair->lhs);
0922     if (size == 0) {
0923         if (strstr((char *)arg_pair->lhs, "["))
0924             return 0;
0925     }
0926 
0927     return size ? 0 : -EINVAL;
0928 }
0929 
0930 /**
0931  * synth_event_add_field - Add a new field to a synthetic event cmd
0932  * @cmd: A pointer to the dynevent_cmd struct representing the new event
0933  * @type: The type of the new field to add
0934  * @name: The name of the new field to add
0935  *
0936  * Add a new field to a synthetic event cmd object.  Field ordering is in
0937  * the same order the fields are added.
0938  *
0939  * See synth_field_size() for available types. If field_name contains
0940  * [n] the field is considered to be an array.
0941  *
0942  * Return: 0 if successful, error otherwise.
0943  */
0944 int synth_event_add_field(struct dynevent_cmd *cmd, const char *type,
0945               const char *name)
0946 {
0947     struct dynevent_arg_pair arg_pair;
0948     int ret;
0949 
0950     if (cmd->type != DYNEVENT_TYPE_SYNTH)
0951         return -EINVAL;
0952 
0953     if (!type || !name)
0954         return -EINVAL;
0955 
0956     dynevent_arg_pair_init(&arg_pair, 0, ';');
0957 
0958     arg_pair.lhs = type;
0959     arg_pair.rhs = name;
0960 
0961     ret = dynevent_arg_pair_add(cmd, &arg_pair, synth_event_check_arg_fn);
0962     if (ret)
0963         return ret;
0964 
0965     if (++cmd->n_fields > SYNTH_FIELDS_MAX)
0966         ret = -EINVAL;
0967 
0968     return ret;
0969 }
0970 EXPORT_SYMBOL_GPL(synth_event_add_field);
0971 
0972 /**
0973  * synth_event_add_field_str - Add a new field to a synthetic event cmd
0974  * @cmd: A pointer to the dynevent_cmd struct representing the new event
0975  * @type_name: The type and name of the new field to add, as a single string
0976  *
0977  * Add a new field to a synthetic event cmd object, as a single
0978  * string.  The @type_name string is expected to be of the form 'type
0979  * name', which will be appended by ';'.  No sanity checking is done -
0980  * what's passed in is assumed to already be well-formed.  Field
0981  * ordering is in the same order the fields are added.
0982  *
0983  * See synth_field_size() for available types. If field_name contains
0984  * [n] the field is considered to be an array.
0985  *
0986  * Return: 0 if successful, error otherwise.
0987  */
0988 int synth_event_add_field_str(struct dynevent_cmd *cmd, const char *type_name)
0989 {
0990     struct dynevent_arg arg;
0991     int ret;
0992 
0993     if (cmd->type != DYNEVENT_TYPE_SYNTH)
0994         return -EINVAL;
0995 
0996     if (!type_name)
0997         return -EINVAL;
0998 
0999     dynevent_arg_init(&arg, ';');
1000 
1001     arg.str = type_name;
1002 
1003     ret = dynevent_arg_add(cmd, &arg, NULL);
1004     if (ret)
1005         return ret;
1006 
1007     if (++cmd->n_fields > SYNTH_FIELDS_MAX)
1008         ret = -EINVAL;
1009 
1010     return ret;
1011 }
1012 EXPORT_SYMBOL_GPL(synth_event_add_field_str);
1013 
1014 /**
1015  * synth_event_add_fields - Add multiple fields to a synthetic event cmd
1016  * @cmd: A pointer to the dynevent_cmd struct representing the new event
1017  * @fields: An array of type/name field descriptions
1018  * @n_fields: The number of field descriptions contained in the fields array
1019  *
1020  * Add a new set of fields to a synthetic event cmd object.  The event
1021  * fields that will be defined for the event should be passed in as an
1022  * array of struct synth_field_desc, and the number of elements in the
1023  * array passed in as n_fields.  Field ordering will retain the
1024  * ordering given in the fields array.
1025  *
1026  * See synth_field_size() for available types. If field_name contains
1027  * [n] the field is considered to be an array.
1028  *
1029  * Return: 0 if successful, error otherwise.
1030  */
1031 int synth_event_add_fields(struct dynevent_cmd *cmd,
1032                struct synth_field_desc *fields,
1033                unsigned int n_fields)
1034 {
1035     unsigned int i;
1036     int ret = 0;
1037 
1038     for (i = 0; i < n_fields; i++) {
1039         if (fields[i].type == NULL || fields[i].name == NULL) {
1040             ret = -EINVAL;
1041             break;
1042         }
1043 
1044         ret = synth_event_add_field(cmd, fields[i].type, fields[i].name);
1045         if (ret)
1046             break;
1047     }
1048 
1049     return ret;
1050 }
1051 EXPORT_SYMBOL_GPL(synth_event_add_fields);
1052 
1053 /**
1054  * __synth_event_gen_cmd_start - Start a synthetic event command from arg list
1055  * @cmd: A pointer to the dynevent_cmd struct representing the new event
1056  * @name: The name of the synthetic event
1057  * @mod: The module creating the event, NULL if not created from a module
1058  * @args: Variable number of arg (pairs), one pair for each field
1059  *
1060  * NOTE: Users normally won't want to call this function directly, but
1061  * rather use the synth_event_gen_cmd_start() wrapper, which
1062  * automatically adds a NULL to the end of the arg list.  If this
1063  * function is used directly, make sure the last arg in the variable
1064  * arg list is NULL.
1065  *
1066  * Generate a synthetic event command to be executed by
1067  * synth_event_gen_cmd_end().  This function can be used to generate
1068  * the complete command or only the first part of it; in the latter
1069  * case, synth_event_add_field(), synth_event_add_field_str(), or
1070  * synth_event_add_fields() can be used to add more fields following
1071  * this.
1072  *
1073  * There should be an even number variable args, each pair consisting
1074  * of a type followed by a field name.
1075  *
1076  * See synth_field_size() for available types. If field_name contains
1077  * [n] the field is considered to be an array.
1078  *
1079  * Return: 0 if successful, error otherwise.
1080  */
1081 int __synth_event_gen_cmd_start(struct dynevent_cmd *cmd, const char *name,
1082                 struct module *mod, ...)
1083 {
1084     struct dynevent_arg arg;
1085     va_list args;
1086     int ret;
1087 
1088     cmd->event_name = name;
1089     cmd->private_data = mod;
1090 
1091     if (cmd->type != DYNEVENT_TYPE_SYNTH)
1092         return -EINVAL;
1093 
1094     dynevent_arg_init(&arg, 0);
1095     arg.str = name;
1096     ret = dynevent_arg_add(cmd, &arg, NULL);
1097     if (ret)
1098         return ret;
1099 
1100     va_start(args, mod);
1101     for (;;) {
1102         const char *type, *name;
1103 
1104         type = va_arg(args, const char *);
1105         if (!type)
1106             break;
1107         name = va_arg(args, const char *);
1108         if (!name)
1109             break;
1110 
1111         if (++cmd->n_fields > SYNTH_FIELDS_MAX) {
1112             ret = -EINVAL;
1113             break;
1114         }
1115 
1116         ret = synth_event_add_field(cmd, type, name);
1117         if (ret)
1118             break;
1119     }
1120     va_end(args);
1121 
1122     return ret;
1123 }
1124 EXPORT_SYMBOL_GPL(__synth_event_gen_cmd_start);
1125 
1126 /**
1127  * synth_event_gen_cmd_array_start - Start synthetic event command from an array
1128  * @cmd: A pointer to the dynevent_cmd struct representing the new event
1129  * @name: The name of the synthetic event
1130  * @fields: An array of type/name field descriptions
1131  * @n_fields: The number of field descriptions contained in the fields array
1132  *
1133  * Generate a synthetic event command to be executed by
1134  * synth_event_gen_cmd_end().  This function can be used to generate
1135  * the complete command or only the first part of it; in the latter
1136  * case, synth_event_add_field(), synth_event_add_field_str(), or
1137  * synth_event_add_fields() can be used to add more fields following
1138  * this.
1139  *
1140  * The event fields that will be defined for the event should be
1141  * passed in as an array of struct synth_field_desc, and the number of
1142  * elements in the array passed in as n_fields.  Field ordering will
1143  * retain the ordering given in the fields array.
1144  *
1145  * See synth_field_size() for available types. If field_name contains
1146  * [n] the field is considered to be an array.
1147  *
1148  * Return: 0 if successful, error otherwise.
1149  */
1150 int synth_event_gen_cmd_array_start(struct dynevent_cmd *cmd, const char *name,
1151                     struct module *mod,
1152                     struct synth_field_desc *fields,
1153                     unsigned int n_fields)
1154 {
1155     struct dynevent_arg arg;
1156     unsigned int i;
1157     int ret = 0;
1158 
1159     cmd->event_name = name;
1160     cmd->private_data = mod;
1161 
1162     if (cmd->type != DYNEVENT_TYPE_SYNTH)
1163         return -EINVAL;
1164 
1165     if (n_fields > SYNTH_FIELDS_MAX)
1166         return -EINVAL;
1167 
1168     dynevent_arg_init(&arg, 0);
1169     arg.str = name;
1170     ret = dynevent_arg_add(cmd, &arg, NULL);
1171     if (ret)
1172         return ret;
1173 
1174     for (i = 0; i < n_fields; i++) {
1175         if (fields[i].type == NULL || fields[i].name == NULL)
1176             return -EINVAL;
1177 
1178         ret = synth_event_add_field(cmd, fields[i].type, fields[i].name);
1179         if (ret)
1180             break;
1181     }
1182 
1183     return ret;
1184 }
1185 EXPORT_SYMBOL_GPL(synth_event_gen_cmd_array_start);
1186 
1187 static int __create_synth_event(const char *name, const char *raw_fields)
1188 {
1189     char **argv, *field_str, *tmp_fields, *saved_fields = NULL;
1190     struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
1191     int consumed, cmd_version = 1, n_fields_this_loop;
1192     int i, argc, n_fields = 0, ret = 0;
1193     struct synth_event *event = NULL;
1194 
1195     /*
1196      * Argument syntax:
1197      *  - Add synthetic event: <event_name> field[;field] ...
1198      *  - Remove synthetic event: !<event_name> field[;field] ...
1199      *      where 'field' = type field_name
1200      */
1201 
1202     if (name[0] == '\0') {
1203         synth_err(SYNTH_ERR_INVALID_CMD, 0);
1204         return -EINVAL;
1205     }
1206 
1207     if (!is_good_name(name)) {
1208         synth_err(SYNTH_ERR_BAD_NAME, errpos(name));
1209         return -EINVAL;
1210     }
1211 
1212     mutex_lock(&event_mutex);
1213 
1214     event = find_synth_event(name);
1215     if (event) {
1216         synth_err(SYNTH_ERR_EVENT_EXISTS, errpos(name));
1217         ret = -EEXIST;
1218         goto err;
1219     }
1220 
1221     tmp_fields = saved_fields = kstrdup(raw_fields, GFP_KERNEL);
1222     if (!tmp_fields) {
1223         ret = -ENOMEM;
1224         goto err;
1225     }
1226 
1227     while ((field_str = strsep(&tmp_fields, ";")) != NULL) {
1228         argv = argv_split(GFP_KERNEL, field_str, &argc);
1229         if (!argv) {
1230             ret = -ENOMEM;
1231             goto err;
1232         }
1233 
1234         if (!argc) {
1235             argv_free(argv);
1236             continue;
1237         }
1238 
1239         n_fields_this_loop = 0;
1240         consumed = 0;
1241         while (argc > consumed) {
1242             int field_version;
1243 
1244             field = parse_synth_field(argc - consumed,
1245                           argv + consumed, &consumed,
1246                           &field_version);
1247             if (IS_ERR(field)) {
1248                 ret = PTR_ERR(field);
1249                 goto err_free_arg;
1250             }
1251 
1252             /*
1253              * Track the highest version of any field we
1254              * found in the command.
1255              */
1256             if (field_version > cmd_version)
1257                 cmd_version = field_version;
1258 
1259             /*
1260              * Now sort out what is and isn't valid for
1261              * each supported version.
1262              *
1263              * If we see more than 1 field per loop, it
1264              * means we have multiple fields between
1265              * semicolons, and that's something we no
1266              * longer support in a version 2 or greater
1267              * command.
1268              */
1269             if (cmd_version > 1 && n_fields_this_loop >= 1) {
1270                 synth_err(SYNTH_ERR_INVALID_CMD, errpos(field_str));
1271                 ret = -EINVAL;
1272                 goto err_free_arg;
1273             }
1274 
1275             fields[n_fields++] = field;
1276             if (n_fields == SYNTH_FIELDS_MAX) {
1277                 synth_err(SYNTH_ERR_TOO_MANY_FIELDS, 0);
1278                 ret = -EINVAL;
1279                 goto err_free_arg;
1280             }
1281 
1282             n_fields_this_loop++;
1283         }
1284         argv_free(argv);
1285 
1286         if (consumed < argc) {
1287             synth_err(SYNTH_ERR_INVALID_CMD, 0);
1288             ret = -EINVAL;
1289             goto err;
1290         }
1291 
1292     }
1293 
1294     if (n_fields == 0) {
1295         synth_err(SYNTH_ERR_INVALID_CMD, 0);
1296         ret = -EINVAL;
1297         goto err;
1298     }
1299 
1300     event = alloc_synth_event(name, n_fields, fields);
1301     if (IS_ERR(event)) {
1302         ret = PTR_ERR(event);
1303         event = NULL;
1304         goto err;
1305     }
1306     ret = register_synth_event(event);
1307     if (!ret)
1308         dyn_event_add(&event->devent, &event->call);
1309     else
1310         free_synth_event(event);
1311  out:
1312     mutex_unlock(&event_mutex);
1313 
1314     kfree(saved_fields);
1315 
1316     return ret;
1317  err_free_arg:
1318     argv_free(argv);
1319  err:
1320     for (i = 0; i < n_fields; i++)
1321         free_synth_field(fields[i]);
1322 
1323     goto out;
1324 }
1325 
1326 /**
1327  * synth_event_create - Create a new synthetic event
1328  * @name: The name of the new synthetic event
1329  * @fields: An array of type/name field descriptions
1330  * @n_fields: The number of field descriptions contained in the fields array
1331  * @mod: The module creating the event, NULL if not created from a module
1332  *
1333  * Create a new synthetic event with the given name under the
1334  * trace/events/synthetic/ directory.  The event fields that will be
1335  * defined for the event should be passed in as an array of struct
1336  * synth_field_desc, and the number elements in the array passed in as
1337  * n_fields. Field ordering will retain the ordering given in the
1338  * fields array.
1339  *
1340  * If the new synthetic event is being created from a module, the mod
1341  * param must be non-NULL.  This will ensure that the trace buffer
1342  * won't contain unreadable events.
1343  *
1344  * The new synth event should be deleted using synth_event_delete()
1345  * function.  The new synthetic event can be generated from modules or
1346  * other kernel code using trace_synth_event() and related functions.
1347  *
1348  * Return: 0 if successful, error otherwise.
1349  */
1350 int synth_event_create(const char *name, struct synth_field_desc *fields,
1351                unsigned int n_fields, struct module *mod)
1352 {
1353     struct dynevent_cmd cmd;
1354     char *buf;
1355     int ret;
1356 
1357     buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
1358     if (!buf)
1359         return -ENOMEM;
1360 
1361     synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);
1362 
1363     ret = synth_event_gen_cmd_array_start(&cmd, name, mod,
1364                           fields, n_fields);
1365     if (ret)
1366         goto out;
1367 
1368     ret = synth_event_gen_cmd_end(&cmd);
1369  out:
1370     kfree(buf);
1371 
1372     return ret;
1373 }
1374 EXPORT_SYMBOL_GPL(synth_event_create);
1375 
1376 static int destroy_synth_event(struct synth_event *se)
1377 {
1378     int ret;
1379 
1380     if (se->ref)
1381         return -EBUSY;
1382 
1383     if (trace_event_dyn_busy(&se->call))
1384         return -EBUSY;
1385 
1386     ret = unregister_synth_event(se);
1387     if (!ret) {
1388         dyn_event_remove(&se->devent);
1389         free_synth_event(se);
1390     }
1391 
1392     return ret;
1393 }
1394 
1395 /**
1396  * synth_event_delete - Delete a synthetic event
1397  * @event_name: The name of the new synthetic event
1398  *
1399  * Delete a synthetic event that was created with synth_event_create().
1400  *
1401  * Return: 0 if successful, error otherwise.
1402  */
1403 int synth_event_delete(const char *event_name)
1404 {
1405     struct synth_event *se = NULL;
1406     struct module *mod = NULL;
1407     int ret = -ENOENT;
1408 
1409     mutex_lock(&event_mutex);
1410     se = find_synth_event(event_name);
1411     if (se) {
1412         mod = se->mod;
1413         ret = destroy_synth_event(se);
1414     }
1415     mutex_unlock(&event_mutex);
1416 
1417     if (mod) {
1418         mutex_lock(&trace_types_lock);
1419         /*
1420          * It is safest to reset the ring buffer if the module
1421          * being unloaded registered any events that were
1422          * used. The only worry is if a new module gets
1423          * loaded, and takes on the same id as the events of
1424          * this module. When printing out the buffer, traced
1425          * events left over from this module may be passed to
1426          * the new module events and unexpected results may
1427          * occur.
1428          */
1429         tracing_reset_all_online_cpus();
1430         mutex_unlock(&trace_types_lock);
1431     }
1432 
1433     return ret;
1434 }
1435 EXPORT_SYMBOL_GPL(synth_event_delete);
1436 
1437 static int check_command(const char *raw_command)
1438 {
1439     char **argv = NULL, *cmd, *saved_cmd, *name_and_field;
1440     int argc, ret = 0;
1441 
1442     cmd = saved_cmd = kstrdup(raw_command, GFP_KERNEL);
1443     if (!cmd)
1444         return -ENOMEM;
1445 
1446     name_and_field = strsep(&cmd, ";");
1447     if (!name_and_field) {
1448         ret = -EINVAL;
1449         goto free;
1450     }
1451 
1452     if (name_and_field[0] == '!')
1453         goto free;
1454 
1455     argv = argv_split(GFP_KERNEL, name_and_field, &argc);
1456     if (!argv) {
1457         ret = -ENOMEM;
1458         goto free;
1459     }
1460     argv_free(argv);
1461 
1462     if (argc < 3)
1463         ret = -EINVAL;
1464 free:
1465     kfree(saved_cmd);
1466 
1467     return ret;
1468 }
1469 
1470 static int create_or_delete_synth_event(const char *raw_command)
1471 {
1472     char *name = NULL, *fields, *p;
1473     int ret = 0;
1474 
1475     raw_command = skip_spaces(raw_command);
1476     if (raw_command[0] == '\0')
1477         return ret;
1478 
1479     last_cmd_set(raw_command);
1480 
1481     ret = check_command(raw_command);
1482     if (ret) {
1483         synth_err(SYNTH_ERR_INVALID_CMD, 0);
1484         return ret;
1485     }
1486 
1487     p = strpbrk(raw_command, " \t");
1488     if (!p && raw_command[0] != '!') {
1489         synth_err(SYNTH_ERR_INVALID_CMD, 0);
1490         ret = -EINVAL;
1491         goto free;
1492     }
1493 
1494     name = kmemdup_nul(raw_command, p ? p - raw_command : strlen(raw_command), GFP_KERNEL);
1495     if (!name)
1496         return -ENOMEM;
1497 
1498     if (name[0] == '!') {
1499         ret = synth_event_delete(name + 1);
1500         goto free;
1501     }
1502 
1503     fields = skip_spaces(p);
1504 
1505     ret = __create_synth_event(name, fields);
1506 free:
1507     kfree(name);
1508 
1509     return ret;
1510 }
1511 
1512 static int synth_event_run_command(struct dynevent_cmd *cmd)
1513 {
1514     struct synth_event *se;
1515     int ret;
1516 
1517     ret = create_or_delete_synth_event(cmd->seq.buffer);
1518     if (ret)
1519         return ret;
1520 
1521     se = find_synth_event(cmd->event_name);
1522     if (WARN_ON(!se))
1523         return -ENOENT;
1524 
1525     se->mod = cmd->private_data;
1526 
1527     return ret;
1528 }
1529 
1530 /**
1531  * synth_event_cmd_init - Initialize a synthetic event command object
1532  * @cmd: A pointer to the dynevent_cmd struct representing the new event
1533  * @buf: A pointer to the buffer used to build the command
1534  * @maxlen: The length of the buffer passed in @buf
1535  *
1536  * Initialize a synthetic event command object.  Use this before
1537  * calling any of the other dyenvent_cmd functions.
1538  */
1539 void synth_event_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen)
1540 {
1541     dynevent_cmd_init(cmd, buf, maxlen, DYNEVENT_TYPE_SYNTH,
1542               synth_event_run_command);
1543 }
1544 EXPORT_SYMBOL_GPL(synth_event_cmd_init);
1545 
1546 static inline int
1547 __synth_event_trace_init(struct trace_event_file *file,
1548              struct synth_event_trace_state *trace_state)
1549 {
1550     int ret = 0;
1551 
1552     memset(trace_state, '\0', sizeof(*trace_state));
1553 
1554     /*
1555      * Normal event tracing doesn't get called at all unless the
1556      * ENABLED bit is set (which attaches the probe thus allowing
1557      * this code to be called, etc).  Because this is called
1558      * directly by the user, we don't have that but we still need
1559      * to honor not logging when disabled.  For the iterated
1560      * trace case, we save the enabled state upon start and just
1561      * ignore the following data calls.
1562      */
1563     if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
1564         trace_trigger_soft_disabled(file)) {
1565         trace_state->disabled = true;
1566         ret = -ENOENT;
1567         goto out;
1568     }
1569 
1570     trace_state->event = file->event_call->data;
1571 out:
1572     return ret;
1573 }
1574 
1575 static inline int
1576 __synth_event_trace_start(struct trace_event_file *file,
1577               struct synth_event_trace_state *trace_state,
1578               int dynamic_fields_size)
1579 {
1580     int entry_size, fields_size = 0;
1581     int ret = 0;
1582 
1583     fields_size = trace_state->event->n_u64 * sizeof(u64);
1584     fields_size += dynamic_fields_size;
1585 
1586     /*
1587      * Avoid ring buffer recursion detection, as this event
1588      * is being performed within another event.
1589      */
1590     trace_state->buffer = file->tr->array_buffer.buffer;
1591     ring_buffer_nest_start(trace_state->buffer);
1592 
1593     entry_size = sizeof(*trace_state->entry) + fields_size;
1594     trace_state->entry = trace_event_buffer_reserve(&trace_state->fbuffer,
1595                             file,
1596                             entry_size);
1597     if (!trace_state->entry) {
1598         ring_buffer_nest_end(trace_state->buffer);
1599         ret = -EINVAL;
1600     }
1601 
1602     return ret;
1603 }
1604 
1605 static inline void
1606 __synth_event_trace_end(struct synth_event_trace_state *trace_state)
1607 {
1608     trace_event_buffer_commit(&trace_state->fbuffer);
1609 
1610     ring_buffer_nest_end(trace_state->buffer);
1611 }
1612 
1613 /**
1614  * synth_event_trace - Trace a synthetic event
1615  * @file: The trace_event_file representing the synthetic event
1616  * @n_vals: The number of values in vals
1617  * @args: Variable number of args containing the event values
1618  *
1619  * Trace a synthetic event using the values passed in the variable
1620  * argument list.
1621  *
1622  * The argument list should be a list 'n_vals' u64 values.  The number
1623  * of vals must match the number of field in the synthetic event, and
1624  * must be in the same order as the synthetic event fields.
1625  *
1626  * All vals should be cast to u64, and string vals are just pointers
1627  * to strings, cast to u64.  Strings will be copied into space
1628  * reserved in the event for the string, using these pointers.
1629  *
1630  * Return: 0 on success, err otherwise.
1631  */
1632 int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
1633 {
1634     unsigned int i, n_u64, len, data_size = 0;
1635     struct synth_event_trace_state state;
1636     va_list args;
1637     int ret;
1638 
1639     ret = __synth_event_trace_init(file, &state);
1640     if (ret) {
1641         if (ret == -ENOENT)
1642             ret = 0; /* just disabled, not really an error */
1643         return ret;
1644     }
1645 
1646     if (state.event->n_dynamic_fields) {
1647         va_start(args, n_vals);
1648 
1649         for (i = 0; i < state.event->n_fields; i++) {
1650             u64 val = va_arg(args, u64);
1651 
1652             if (state.event->fields[i]->is_string &&
1653                 state.event->fields[i]->is_dynamic) {
1654                 char *str_val = (char *)(long)val;
1655 
1656                 data_size += strlen(str_val) + 1;
1657             }
1658         }
1659 
1660         va_end(args);
1661     }
1662 
1663     ret = __synth_event_trace_start(file, &state, data_size);
1664     if (ret)
1665         return ret;
1666 
1667     if (n_vals != state.event->n_fields) {
1668         ret = -EINVAL;
1669         goto out;
1670     }
1671 
1672     data_size = 0;
1673 
1674     va_start(args, n_vals);
1675     for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
1676         u64 val;
1677 
1678         val = va_arg(args, u64);
1679 
1680         if (state.event->fields[i]->is_string) {
1681             char *str_val = (char *)(long)val;
1682 
1683             len = trace_string(state.entry, state.event, str_val,
1684                        state.event->fields[i]->is_dynamic,
1685                        data_size, &n_u64);
1686             data_size += len; /* only dynamic string increments */
1687         } else {
1688             struct synth_field *field = state.event->fields[i];
1689 
1690             switch (field->size) {
1691             case 1:
1692                 *(u8 *)&state.entry->fields[n_u64] = (u8)val;
1693                 break;
1694 
1695             case 2:
1696                 *(u16 *)&state.entry->fields[n_u64] = (u16)val;
1697                 break;
1698 
1699             case 4:
1700                 *(u32 *)&state.entry->fields[n_u64] = (u32)val;
1701                 break;
1702 
1703             default:
1704                 state.entry->fields[n_u64] = val;
1705                 break;
1706             }
1707             n_u64++;
1708         }
1709     }
1710     va_end(args);
1711 out:
1712     __synth_event_trace_end(&state);
1713 
1714     return ret;
1715 }
1716 EXPORT_SYMBOL_GPL(synth_event_trace);
1717 
1718 /**
1719  * synth_event_trace_array - Trace a synthetic event from an array
1720  * @file: The trace_event_file representing the synthetic event
1721  * @vals: Array of values
1722  * @n_vals: The number of values in vals
1723  *
1724  * Trace a synthetic event using the values passed in as 'vals'.
1725  *
1726  * The 'vals' array is just an array of 'n_vals' u64.  The number of
1727  * vals must match the number of field in the synthetic event, and
1728  * must be in the same order as the synthetic event fields.
1729  *
1730  * All vals should be cast to u64, and string vals are just pointers
1731  * to strings, cast to u64.  Strings will be copied into space
1732  * reserved in the event for the string, using these pointers.
1733  *
1734  * Return: 0 on success, err otherwise.
1735  */
1736 int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
1737                 unsigned int n_vals)
1738 {
1739     unsigned int i, n_u64, field_pos, len, data_size = 0;
1740     struct synth_event_trace_state state;
1741     char *str_val;
1742     int ret;
1743 
1744     ret = __synth_event_trace_init(file, &state);
1745     if (ret) {
1746         if (ret == -ENOENT)
1747             ret = 0; /* just disabled, not really an error */
1748         return ret;
1749     }
1750 
1751     if (state.event->n_dynamic_fields) {
1752         for (i = 0; i < state.event->n_dynamic_fields; i++) {
1753             field_pos = state.event->dynamic_fields[i]->field_pos;
1754             str_val = (char *)(long)vals[field_pos];
1755             len = strlen(str_val) + 1;
1756             data_size += len;
1757         }
1758     }
1759 
1760     ret = __synth_event_trace_start(file, &state, data_size);
1761     if (ret)
1762         return ret;
1763 
1764     if (n_vals != state.event->n_fields) {
1765         ret = -EINVAL;
1766         goto out;
1767     }
1768 
1769     data_size = 0;
1770 
1771     for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
1772         if (state.event->fields[i]->is_string) {
1773             char *str_val = (char *)(long)vals[i];
1774 
1775             len = trace_string(state.entry, state.event, str_val,
1776                        state.event->fields[i]->is_dynamic,
1777                        data_size, &n_u64);
1778             data_size += len; /* only dynamic string increments */
1779         } else {
1780             struct synth_field *field = state.event->fields[i];
1781             u64 val = vals[i];
1782 
1783             switch (field->size) {
1784             case 1:
1785                 *(u8 *)&state.entry->fields[n_u64] = (u8)val;
1786                 break;
1787 
1788             case 2:
1789                 *(u16 *)&state.entry->fields[n_u64] = (u16)val;
1790                 break;
1791 
1792             case 4:
1793                 *(u32 *)&state.entry->fields[n_u64] = (u32)val;
1794                 break;
1795 
1796             default:
1797                 state.entry->fields[n_u64] = val;
1798                 break;
1799             }
1800             n_u64++;
1801         }
1802     }
1803 out:
1804     __synth_event_trace_end(&state);
1805 
1806     return ret;
1807 }
1808 EXPORT_SYMBOL_GPL(synth_event_trace_array);
1809 
1810 /**
1811  * synth_event_trace_start - Start piecewise synthetic event trace
1812  * @file: The trace_event_file representing the synthetic event
1813  * @trace_state: A pointer to object tracking the piecewise trace state
1814  *
1815  * Start the trace of a synthetic event field-by-field rather than all
1816  * at once.
1817  *
1818  * This function 'opens' an event trace, which means space is reserved
1819  * for the event in the trace buffer, after which the event's
1820  * individual field values can be set through either
1821  * synth_event_add_next_val() or synth_event_add_val().
1822  *
1823  * A pointer to a trace_state object is passed in, which will keep
1824  * track of the current event trace state until the event trace is
1825  * closed (and the event finally traced) using
1826  * synth_event_trace_end().
1827  *
1828  * Note that synth_event_trace_end() must be called after all values
1829  * have been added for each event trace, regardless of whether adding
1830  * all field values succeeded or not.
1831  *
1832  * Note also that for a given event trace, all fields must be added
1833  * using either synth_event_add_next_val() or synth_event_add_val()
1834  * but not both together or interleaved.
1835  *
1836  * Return: 0 on success, err otherwise.
1837  */
1838 int synth_event_trace_start(struct trace_event_file *file,
1839                 struct synth_event_trace_state *trace_state)
1840 {
1841     int ret;
1842 
1843     if (!trace_state)
1844         return -EINVAL;
1845 
1846     ret = __synth_event_trace_init(file, trace_state);
1847     if (ret) {
1848         if (ret == -ENOENT)
1849             ret = 0; /* just disabled, not really an error */
1850         return ret;
1851     }
1852 
1853     if (trace_state->event->n_dynamic_fields)
1854         return -ENOTSUPP;
1855 
1856     ret = __synth_event_trace_start(file, trace_state, 0);
1857 
1858     return ret;
1859 }
1860 EXPORT_SYMBOL_GPL(synth_event_trace_start);
1861 
1862 static int __synth_event_add_val(const char *field_name, u64 val,
1863                  struct synth_event_trace_state *trace_state)
1864 {
1865     struct synth_field *field = NULL;
1866     struct synth_trace_event *entry;
1867     struct synth_event *event;
1868     int i, ret = 0;
1869 
1870     if (!trace_state) {
1871         ret = -EINVAL;
1872         goto out;
1873     }
1874 
1875     /* can't mix add_next_synth_val() with add_synth_val() */
1876     if (field_name) {
1877         if (trace_state->add_next) {
1878             ret = -EINVAL;
1879             goto out;
1880         }
1881         trace_state->add_name = true;
1882     } else {
1883         if (trace_state->add_name) {
1884             ret = -EINVAL;
1885             goto out;
1886         }
1887         trace_state->add_next = true;
1888     }
1889 
1890     if (trace_state->disabled)
1891         goto out;
1892 
1893     event = trace_state->event;
1894     if (trace_state->add_name) {
1895         for (i = 0; i < event->n_fields; i++) {
1896             field = event->fields[i];
1897             if (strcmp(field->name, field_name) == 0)
1898                 break;
1899         }
1900         if (!field) {
1901             ret = -EINVAL;
1902             goto out;
1903         }
1904     } else {
1905         if (trace_state->cur_field >= event->n_fields) {
1906             ret = -EINVAL;
1907             goto out;
1908         }
1909         field = event->fields[trace_state->cur_field++];
1910     }
1911 
1912     entry = trace_state->entry;
1913     if (field->is_string) {
1914         char *str_val = (char *)(long)val;
1915         char *str_field;
1916 
1917         if (field->is_dynamic) { /* add_val can't do dynamic strings */
1918             ret = -EINVAL;
1919             goto out;
1920         }
1921 
1922         if (!str_val) {
1923             ret = -EINVAL;
1924             goto out;
1925         }
1926 
1927         str_field = (char *)&entry->fields[field->offset];
1928         strscpy(str_field, str_val, STR_VAR_LEN_MAX);
1929     } else {
1930         switch (field->size) {
1931         case 1:
1932             *(u8 *)&trace_state->entry->fields[field->offset] = (u8)val;
1933             break;
1934 
1935         case 2:
1936             *(u16 *)&trace_state->entry->fields[field->offset] = (u16)val;
1937             break;
1938 
1939         case 4:
1940             *(u32 *)&trace_state->entry->fields[field->offset] = (u32)val;
1941             break;
1942 
1943         default:
1944             trace_state->entry->fields[field->offset] = val;
1945             break;
1946         }
1947     }
1948  out:
1949     return ret;
1950 }
1951 
1952 /**
1953  * synth_event_add_next_val - Add the next field's value to an open synth trace
1954  * @val: The value to set the next field to
1955  * @trace_state: A pointer to object tracking the piecewise trace state
1956  *
1957  * Set the value of the next field in an event that's been opened by
1958  * synth_event_trace_start().
1959  *
1960  * The val param should be the value cast to u64.  If the value points
1961  * to a string, the val param should be a char * cast to u64.
1962  *
1963  * This function assumes all the fields in an event are to be set one
1964  * after another - successive calls to this function are made, one for
1965  * each field, in the order of the fields in the event, until all
1966  * fields have been set.  If you'd rather set each field individually
1967  * without regard to ordering, synth_event_add_val() can be used
1968  * instead.
1969  *
1970  * Note however that synth_event_add_next_val() and
1971  * synth_event_add_val() can't be intermixed for a given event trace -
1972  * one or the other but not both can be used at the same time.
1973  *
1974  * Note also that synth_event_trace_end() must be called after all
1975  * values have been added for each event trace, regardless of whether
1976  * adding all field values succeeded or not.
1977  *
1978  * Return: 0 on success, err otherwise.
1979  */
1980 int synth_event_add_next_val(u64 val,
1981                  struct synth_event_trace_state *trace_state)
1982 {
1983     return __synth_event_add_val(NULL, val, trace_state);
1984 }
1985 EXPORT_SYMBOL_GPL(synth_event_add_next_val);
1986 
1987 /**
1988  * synth_event_add_val - Add a named field's value to an open synth trace
1989  * @field_name: The name of the synthetic event field value to set
1990  * @val: The value to set the named field to
1991  * @trace_state: A pointer to object tracking the piecewise trace state
1992  *
1993  * Set the value of the named field in an event that's been opened by
1994  * synth_event_trace_start().
1995  *
1996  * The val param should be the value cast to u64.  If the value points
1997  * to a string, the val param should be a char * cast to u64.
1998  *
1999  * This function looks up the field name, and if found, sets the field
2000  * to the specified value.  This lookup makes this function more
2001  * expensive than synth_event_add_next_val(), so use that or the
2002  * none-piecewise synth_event_trace() instead if efficiency is more
2003  * important.
2004  *
2005  * Note however that synth_event_add_next_val() and
2006  * synth_event_add_val() can't be intermixed for a given event trace -
2007  * one or the other but not both can be used at the same time.
2008  *
2009  * Note also that synth_event_trace_end() must be called after all
2010  * values have been added for each event trace, regardless of whether
2011  * adding all field values succeeded or not.
2012  *
2013  * Return: 0 on success, err otherwise.
2014  */
2015 int synth_event_add_val(const char *field_name, u64 val,
2016             struct synth_event_trace_state *trace_state)
2017 {
2018     return __synth_event_add_val(field_name, val, trace_state);
2019 }
2020 EXPORT_SYMBOL_GPL(synth_event_add_val);
2021 
2022 /**
2023  * synth_event_trace_end - End piecewise synthetic event trace
2024  * @trace_state: A pointer to object tracking the piecewise trace state
2025  *
2026  * End the trace of a synthetic event opened by
2027  * synth_event_trace__start().
2028  *
2029  * This function 'closes' an event trace, which basically means that
2030  * it commits the reserved event and cleans up other loose ends.
2031  *
2032  * A pointer to a trace_state object is passed in, which will keep
2033  * track of the current event trace state opened with
2034  * synth_event_trace_start().
2035  *
2036  * Note that this function must be called after all values have been
2037  * added for each event trace, regardless of whether adding all field
2038  * values succeeded or not.
2039  *
2040  * Return: 0 on success, err otherwise.
2041  */
2042 int synth_event_trace_end(struct synth_event_trace_state *trace_state)
2043 {
2044     if (!trace_state)
2045         return -EINVAL;
2046 
2047     __synth_event_trace_end(trace_state);
2048 
2049     return 0;
2050 }
2051 EXPORT_SYMBOL_GPL(synth_event_trace_end);
2052 
2053 static int create_synth_event(const char *raw_command)
2054 {
2055     char *fields, *p;
2056     const char *name;
2057     int len, ret = 0;
2058 
2059     raw_command = skip_spaces(raw_command);
2060     if (raw_command[0] == '\0')
2061         return ret;
2062 
2063     last_cmd_set(raw_command);
2064 
2065     name = raw_command;
2066 
2067     /* Don't try to process if not our system */
2068     if (name[0] != 's' || name[1] != ':')
2069         return -ECANCELED;
2070     name += 2;
2071 
2072     p = strpbrk(raw_command, " \t");
2073     if (!p) {
2074         synth_err(SYNTH_ERR_INVALID_CMD, 0);
2075         return -EINVAL;
2076     }
2077 
2078     fields = skip_spaces(p);
2079 
2080     /* This interface accepts group name prefix */
2081     if (strchr(name, '/')) {
2082         len = str_has_prefix(name, SYNTH_SYSTEM "/");
2083         if (len == 0) {
2084             synth_err(SYNTH_ERR_INVALID_DYN_CMD, 0);
2085             return -EINVAL;
2086         }
2087         name += len;
2088     }
2089 
2090     len = name - raw_command;
2091 
2092     ret = check_command(raw_command + len);
2093     if (ret) {
2094         synth_err(SYNTH_ERR_INVALID_CMD, 0);
2095         return ret;
2096     }
2097 
2098     name = kmemdup_nul(raw_command + len, p - raw_command - len, GFP_KERNEL);
2099     if (!name)
2100         return -ENOMEM;
2101 
2102     ret = __create_synth_event(name, fields);
2103 
2104     kfree(name);
2105 
2106     return ret;
2107 }
2108 
2109 static int synth_event_release(struct dyn_event *ev)
2110 {
2111     struct synth_event *event = to_synth_event(ev);
2112     int ret;
2113 
2114     if (event->ref)
2115         return -EBUSY;
2116 
2117     if (trace_event_dyn_busy(&event->call))
2118         return -EBUSY;
2119 
2120     ret = unregister_synth_event(event);
2121     if (ret)
2122         return ret;
2123 
2124     dyn_event_remove(ev);
2125     free_synth_event(event);
2126     return 0;
2127 }
2128 
2129 static int __synth_event_show(struct seq_file *m, struct synth_event *event)
2130 {
2131     struct synth_field *field;
2132     unsigned int i;
2133     char *type, *t;
2134 
2135     seq_printf(m, "%s\t", event->name);
2136 
2137     for (i = 0; i < event->n_fields; i++) {
2138         field = event->fields[i];
2139 
2140         type = field->type;
2141         t = strstr(type, "__data_loc");
2142         if (t) { /* __data_loc belongs in format but not event desc */
2143             t += sizeof("__data_loc");
2144             type = t;
2145         }
2146 
2147         /* parameter values */
2148         seq_printf(m, "%s %s%s", type, field->name,
2149                i == event->n_fields - 1 ? "" : "; ");
2150     }
2151 
2152     seq_putc(m, '\n');
2153 
2154     return 0;
2155 }
2156 
2157 static int synth_event_show(struct seq_file *m, struct dyn_event *ev)
2158 {
2159     struct synth_event *event = to_synth_event(ev);
2160 
2161     seq_printf(m, "s:%s/", event->class.system);
2162 
2163     return __synth_event_show(m, event);
2164 }
2165 
2166 static int synth_events_seq_show(struct seq_file *m, void *v)
2167 {
2168     struct dyn_event *ev = v;
2169 
2170     if (!is_synth_event(ev))
2171         return 0;
2172 
2173     return __synth_event_show(m, to_synth_event(ev));
2174 }
2175 
2176 static const struct seq_operations synth_events_seq_op = {
2177     .start  = dyn_event_seq_start,
2178     .next   = dyn_event_seq_next,
2179     .stop   = dyn_event_seq_stop,
2180     .show   = synth_events_seq_show,
2181 };
2182 
2183 static int synth_events_open(struct inode *inode, struct file *file)
2184 {
2185     int ret;
2186 
2187     ret = security_locked_down(LOCKDOWN_TRACEFS);
2188     if (ret)
2189         return ret;
2190 
2191     if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
2192         ret = dyn_events_release_all(&synth_event_ops);
2193         if (ret < 0)
2194             return ret;
2195     }
2196 
2197     return seq_open(file, &synth_events_seq_op);
2198 }
2199 
2200 static ssize_t synth_events_write(struct file *file,
2201                   const char __user *buffer,
2202                   size_t count, loff_t *ppos)
2203 {
2204     return trace_parse_run_command(file, buffer, count, ppos,
2205                        create_or_delete_synth_event);
2206 }
2207 
2208 static const struct file_operations synth_events_fops = {
2209     .open           = synth_events_open,
2210     .write      = synth_events_write,
2211     .read           = seq_read,
2212     .llseek         = seq_lseek,
2213     .release        = seq_release,
2214 };
2215 
2216 /*
2217  * Register dynevent at core_initcall. This allows kernel to setup kprobe
2218  * events in postcore_initcall without tracefs.
2219  */
2220 static __init int trace_events_synth_init_early(void)
2221 {
2222     int err = 0;
2223 
2224     err = dyn_event_register(&synth_event_ops);
2225     if (err)
2226         pr_warn("Could not register synth_event_ops\n");
2227 
2228     return err;
2229 }
2230 core_initcall(trace_events_synth_init_early);
2231 
2232 static __init int trace_events_synth_init(void)
2233 {
2234     struct dentry *entry = NULL;
2235     int err = 0;
2236     err = tracing_init_dentry();
2237     if (err)
2238         goto err;
2239 
2240     entry = tracefs_create_file("synthetic_events", TRACE_MODE_WRITE,
2241                     NULL, NULL, &synth_events_fops);
2242     if (!entry) {
2243         err = -ENODEV;
2244         goto err;
2245     }
2246 
2247     return err;
2248  err:
2249     pr_warn("Could not create tracefs 'synthetic_events' entry\n");
2250 
2251     return err;
2252 }
2253 
2254 fs_initcall(trace_events_synth_init);
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