From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Allow fprobe_events to trace raw tracepoints so that user can trace tracepoints which don't have traceevent wrappers. This new event is always available if the fprobe_events is enabled (thus no kconfig), because the fprobe_events depends on the trace-event and traceporint. e.g. # echo 't sched_overutilized_tp' >> dynamic_events # echo 't 9p_client_req' >> dynamic_events # cat dynamic_events t:tracepoints/sched_overutilized_tp sched_overutilized_tp t:tracepoints/_9p_client_req 9p_client_req The event name is based on the tracepoint name, but if it is started with digit character, an underscore '_' will be added. NOTE: to avoid further confusion, this renames TPARG_FL_TPOINT to TPARG_FL_TEVENT because this flag is used for eprobe (trace-event probe). And reuse TPARG_FL_TPOINT for this raw tracepoint probe. Reported-by: kernel test robot <lkp@xxxxxxxxx> Link: https://lore.kernel.org/oe-kbuild-all/202305020453.afTJ3VVp-lkp@xxxxxxxxx/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> --- Changes in v13: - Add a comment about new flags. Changes in v9.1: - Fix !CONFIG_MODULES case. Changes in v6: - Update description - Make find_tracepoint() static. - Fix some checkpatches warnings. --- include/linux/tracepoint-defs.h | 1 include/linux/tracepoint.h | 5 + kernel/trace/trace.c | 1 kernel/trace/trace_eprobe.c | 2 - kernel/trace/trace_fprobe.c | 134 +++++++++++++++++++++++++++++++++++++-- kernel/trace/trace_probe.c | 15 +++- kernel/trace/trace_probe.h | 15 +++- 7 files changed, 157 insertions(+), 16 deletions(-) diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h index e7c2276be33e..4dc4955f0fbf 100644 --- a/include/linux/tracepoint-defs.h +++ b/include/linux/tracepoint-defs.h @@ -35,6 +35,7 @@ struct tracepoint { struct static_call_key *static_call_key; void *static_call_tramp; void *iterator; + void *probestub; int (*regfunc)(void); void (*unregfunc)(void); struct tracepoint_func __rcu *funcs; diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 6811e43c1b5c..88c0ba623ee6 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -303,6 +303,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) __section("__tracepoints_strings") = #_name; \ extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \ int __traceiter_##_name(void *__data, proto); \ + void __probestub_##_name(void *__data, proto); \ struct tracepoint __tracepoint_##_name __used \ __section("__tracepoints") = { \ .name = __tpstrtab_##_name, \ @@ -310,6 +311,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \ .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \ .iterator = &__traceiter_##_name, \ + .probestub = &__probestub_##_name, \ .regfunc = _reg, \ .unregfunc = _unreg, \ .funcs = NULL }; \ @@ -330,6 +332,9 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) } \ return 0; \ } \ + void __probestub_##_name(void *__data, proto) \ + { \ + } \ DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); #define DEFINE_TRACE(name, proto, args) \ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d595cef93122..abcc2ca615e8 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5653,6 +5653,7 @@ static const char readme_msg[] = #endif #ifdef CONFIG_FPROBE_EVENTS "\t f[:[<group>/][<event>]] <func-name>[%return] [<args>]\n" + "\t t[:[<group>/][<event>]] <tracepoint> [<args>]\n" #endif #ifdef CONFIG_HIST_TRIGGERS "\t s:[synthetic/]<event> <field> [<field>]\n" diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index 67e854979d53..fd64cd5d5745 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -817,7 +817,7 @@ find_and_get_event(const char *system, const char *event_name) static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[], int i) { - unsigned int flags = TPARG_FL_KERNEL | TPARG_FL_TPOINT; + unsigned int flags = TPARG_FL_KERNEL | TPARG_FL_TEVENT; int ret; ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], flags); diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index 48dbbc72b7dd..aa71ccb4205c 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -9,6 +9,7 @@ #include <linux/module.h> #include <linux/rculist.h> #include <linux/security.h> +#include <linux/tracepoint.h> #include <linux/uaccess.h> #include "trace_dynevent.h" @@ -17,6 +18,7 @@ #include "trace_probe_tmpl.h" #define FPROBE_EVENT_SYSTEM "fprobes" +#define TRACEPOINT_EVENT_SYSTEM "tracepoints" #define RETHOOK_MAXACTIVE_MAX 4096 static int trace_fprobe_create(const char *raw_command); @@ -41,6 +43,8 @@ struct trace_fprobe { struct dyn_event devent; struct fprobe fp; const char *symbol; + struct tracepoint *tpoint; + struct module *mod; struct trace_probe tp; }; @@ -68,6 +72,11 @@ static bool trace_fprobe_is_return(struct trace_fprobe *tf) return tf->fp.exit_handler != NULL; } +static bool trace_fprobe_is_tracepoint(struct trace_fprobe *tf) +{ + return tf->tpoint != NULL; +} + static const char *trace_fprobe_symbol(struct trace_fprobe *tf) { return tf->symbol ? tf->symbol : "unknown"; @@ -668,6 +677,21 @@ static int __register_trace_fprobe(struct trace_fprobe *tf) else tf->fp.flags |= FPROBE_FL_DISABLED; + if (trace_fprobe_is_tracepoint(tf)) { + struct tracepoint *tpoint = tf->tpoint; + unsigned long ip = (unsigned long)tpoint->probestub; + /* + * Here, we do 2 steps to enable fprobe on a tracepoint. + * At first, put __probestub_##TP function on the tracepoint + * and put a fprobe on the stub function. + */ + ret = tracepoint_probe_register_prio_may_exist(tpoint, + tpoint->probestub, NULL, 0); + if (ret < 0) + return ret; + return register_fprobe_ips(&tf->fp, &ip, 1); + } + /* TODO: handle filter, nofilter or symbol list */ return register_fprobe(&tf->fp, tf->symbol, NULL); } @@ -678,6 +702,12 @@ static void __unregister_trace_fprobe(struct trace_fprobe *tf) if (trace_fprobe_is_registered(tf)) { unregister_fprobe(&tf->fp); memset(&tf->fp, 0, sizeof(tf->fp)); + if (trace_fprobe_is_tracepoint(tf)) { + tracepoint_probe_unregister(tf->tpoint, + tf->tpoint->probestub, NULL); + tf->tpoint = NULL; + tf->mod = NULL; + } } } @@ -741,7 +771,8 @@ static int append_trace_fprobe(struct trace_fprobe *tf, struct trace_fprobe *to) { int ret; - if (trace_fprobe_is_return(tf) != trace_fprobe_is_return(to)) { + if (trace_fprobe_is_return(tf) != trace_fprobe_is_return(to) || + trace_fprobe_is_tracepoint(tf) != trace_fprobe_is_tracepoint(to)) { trace_probe_log_set_index(0); trace_probe_log_err(0, DIFF_PROBE_TYPE); return -EEXIST; @@ -811,6 +842,60 @@ static int register_trace_fprobe(struct trace_fprobe *tf) return ret; } +#ifdef CONFIG_MODULES +static int __tracepoint_probe_module_cb(struct notifier_block *self, + unsigned long val, void *data) +{ + struct tp_module *tp_mod = data; + struct trace_fprobe *tf; + struct dyn_event *pos; + + if (val != MODULE_STATE_GOING) + return NOTIFY_DONE; + + mutex_lock(&event_mutex); + for_each_trace_fprobe(tf, pos) { + if (tp_mod->mod == tf->mod) { + tracepoint_probe_unregister(tf->tpoint, + tf->tpoint->probestub, NULL); + tf->tpoint = NULL; + tf->mod = NULL; + } + } + mutex_unlock(&event_mutex); + + return NOTIFY_DONE; +} + +static struct notifier_block tracepoint_module_nb = { + .notifier_call = __tracepoint_probe_module_cb, +}; +#endif /* CONFIG_MODULES */ + +struct __find_tracepoint_cb_data { + const char *tp_name; + struct tracepoint *tpoint; +}; + +static void __find_tracepoint_cb(struct tracepoint *tp, void *priv) +{ + struct __find_tracepoint_cb_data *data = priv; + + if (!data->tpoint && !strcmp(data->tp_name, tp->name)) + data->tpoint = tp; +} + +static struct tracepoint *find_tracepoint(const char *tp_name) +{ + struct __find_tracepoint_cb_data data = { + .tp_name = tp_name, + }; + + for_each_kernel_tracepoint(__find_tracepoint_cb, &data); + + return data.tpoint; +} + static int __trace_fprobe_create(int argc, const char *argv[]) { /* @@ -819,6 +904,8 @@ static int __trace_fprobe_create(int argc, const char *argv[]) * f[:[GRP/][EVENT]] [MOD:]KSYM [FETCHARGS] * - Add fexit probe: * f[N][:[GRP/][EVENT]] [MOD:]KSYM%return [FETCHARGS] + * - Add tracepoint probe: + * t[:[GRP/][EVENT]] TRACEPOINT [FETCHARGS] * * Fetch args: * $retval : fetch return value @@ -844,10 +931,16 @@ static int __trace_fprobe_create(int argc, const char *argv[]) char buf[MAX_EVENT_NAME_LEN]; char gbuf[MAX_EVENT_NAME_LEN]; unsigned int flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE; + bool is_tracepoint = false; - if (argv[0][0] != 'f' || argc < 2) + if ((argv[0][0] != 'f' && argv[0][0] != 't') || argc < 2) return -ECANCELED; + if (argv[0][0] == 't') { + is_tracepoint = true; + group = TRACEPOINT_EVENT_SYSTEM; + } + trace_probe_log_init("trace_fprobe", argc, argv); event = strchr(&argv[0][1], ':'); @@ -881,14 +974,14 @@ static int __trace_fprobe_create(int argc, const char *argv[]) trace_probe_log_set_index(1); - /* a symbol specified */ + /* a symbol(or tracepoint) must be specified */ symbol = kstrdup(argv[1], GFP_KERNEL); if (!symbol) return -ENOMEM; tmp = strchr(symbol, '%'); if (tmp) { - if (!strcmp(tmp, "%return")) { + if (!is_tracepoint && !strcmp(tmp, "%return")) { *tmp = '\0'; is_return = true; } else { @@ -907,6 +1000,9 @@ static int __trace_fprobe_create(int argc, const char *argv[]) else flags |= TPARG_FL_FENTRY; + if (is_tracepoint) + flags |= TPARG_FL_TPOINT; + trace_probe_log_set_index(0); if (event) { ret = traceprobe_parse_event_name(&event, &group, gbuf, @@ -917,8 +1013,11 @@ static int __trace_fprobe_create(int argc, const char *argv[]) if (!event) { /* Make a new event name */ - snprintf(buf, MAX_EVENT_NAME_LEN, "%s__%s", symbol, - is_return ? "exit" : "entry"); + if (is_tracepoint) + strscpy(buf, symbol, MAX_EVENT_NAME_LEN); + else + snprintf(buf, MAX_EVENT_NAME_LEN, "%s__%s", symbol, + is_return ? "exit" : "entry"); sanitize_event_name(buf); event = buf; } @@ -932,6 +1031,18 @@ static int __trace_fprobe_create(int argc, const char *argv[]) WARN_ON_ONCE(ret != -ENOMEM); goto out; /* We know tf is not allocated */ } + + if (is_tracepoint) { + tf->tpoint = find_tracepoint(tf->symbol); + if (!tf->tpoint) { + trace_probe_log_set_index(1); + trace_probe_log_err(0, NO_TRACEPOINT); + goto parse_error; + } + tf->mod = __module_text_address( + (unsigned long)tf->tpoint->probestub); + } + argc -= 2; argv += 2; /* parse arguments */ @@ -991,7 +1102,10 @@ static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev) struct trace_fprobe *tf = to_trace_fprobe(ev); int i; - seq_putc(m, 'f'); + if (trace_fprobe_is_tracepoint(tf)) + seq_putc(m, 't'); + else + seq_putc(m, 'f'); if (trace_fprobe_is_return(tf) && tf->fp.nr_maxactive) seq_printf(m, "%d", tf->fp.nr_maxactive); seq_printf(m, ":%s/%s", trace_probe_group_name(&tf->tp), @@ -1048,6 +1162,12 @@ static __init int init_fprobe_trace_early(void) if (ret) return ret; +#ifdef CONFIG_MODULES + ret = register_tracepoint_module_notifier(&tracepoint_module_nb); + if (ret) + return ret; +#endif + return 0; } core_initcall(init_fprobe_trace_early); diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 8646b097d56c..dffbed2ddae9 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -292,7 +292,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t, int ret = 0; int len; - if (flags & TPARG_FL_TPOINT) { + if (flags & TPARG_FL_TEVENT) { if (code->data) return -EFAULT; code->data = kstrdup(arg, GFP_KERNEL); @@ -326,8 +326,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t, } else if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) { code->op = FETCH_OP_COMM; #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API - } else if (((flags & TPARG_FL_MASK) == - (TPARG_FL_KERNEL | TPARG_FL_FENTRY)) && + } else if (tparg_is_function_entry(flags) && (len = str_has_prefix(arg, "arg"))) { ret = kstrtoul(arg + len, 10, ¶m); if (ret) { @@ -338,6 +337,12 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t, } code->op = FETCH_OP_ARG; code->param = (unsigned int)param - 1; + /* + * The tracepoint probe will probe a stub function, and the + * first parameter of the stub is a dummy and should be ignored. + */ + if (flags & TPARG_FL_TPOINT) + code->param++; #endif } else goto inval_var; @@ -393,7 +398,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type, break; case '%': /* named register */ - if (flags & (TPARG_FL_TPOINT | TPARG_FL_FPROBE)) { + if (flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE)) { /* eprobe and fprobe do not handle registers */ trace_probe_log_err(offs, BAD_VAR); break; @@ -633,7 +638,7 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, * Since $comm and immediate string can not be dereferenced, * we can find those by strcmp. But ignore for eprobes. */ - if (!(flags & TPARG_FL_TPOINT) && + if (!(flags & TPARG_FL_TEVENT) && (strcmp(arg, "$comm") == 0 || strcmp(arg, "$COMM") == 0 || strncmp(arg, "\\\"", 2) == 0)) { /* The type of $comm must be "string", and not an array. */ diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index cf146a7b7f81..7a0703c00a7d 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -359,16 +359,24 @@ int trace_probe_print_args(struct trace_seq *s, struct probe_arg *args, int nr_a /* * The flags used for parsing trace_probe arguments. - * TPARG_FL_RETURN, TPARG_FL_FENTRY and TPARG_FL_TPOINT are mutually exclusive. + * TPARG_FL_RETURN, TPARG_FL_FENTRY and TPARG_FL_TEVENT are mutually exclusive. * TPARG_FL_KERNEL and TPARG_FL_USER are also mutually exclusive. + * TPARG_FL_FPROBE and TPARG_FL_TPOINT are optional but it should be with + * TPARG_FL_KERNEL. */ #define TPARG_FL_RETURN BIT(0) #define TPARG_FL_KERNEL BIT(1) #define TPARG_FL_FENTRY BIT(2) -#define TPARG_FL_TPOINT BIT(3) +#define TPARG_FL_TEVENT BIT(3) #define TPARG_FL_USER BIT(4) #define TPARG_FL_FPROBE BIT(5) -#define TPARG_FL_MASK GENMASK(4, 0) +#define TPARG_FL_TPOINT BIT(6) +#define TPARG_FL_LOC_MASK GENMASK(4, 0) + +static inline bool tparg_is_function_entry(unsigned int flags) +{ + return (flags & TPARG_FL_LOC_MASK) == (TPARG_FL_KERNEL | TPARG_FL_FENTRY); +} extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, const char *argv, unsigned int flags); @@ -415,6 +423,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, C(MAXACT_TOO_BIG, "Maxactive is too big"), \ C(BAD_PROBE_ADDR, "Invalid probed address or symbol"), \ C(BAD_RETPROBE, "Retprobe address must be an function entry"), \ + C(NO_TRACEPOINT, "Tracepoint is not found"), \ C(BAD_ADDR_SUFFIX, "Invalid probed address suffix"), \ C(NO_GROUP_NAME, "Group name is not specified"), \ C(GROUP_TOO_LONG, "Group name is too long"), \
