Merge tag 'ftrace-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ftrace updates from Steven Rostedt:

 - Have fprobes built on top of function graph infrastructure

   The fprobe logic is an optimized kprobe that uses ftrace to attach to
   functions when a probe is needed at the start or end of the function.
   The fprobe and kretprobe logic implements a similar method as the
   function graph tracer to trace the end of the function. That is to
   hijack the return address and jump to a trampoline to do the trace
   when the function exits. To do this, a shadow stack needs to be
   created to store the original return address. Fprobes and function
   graph do this slightly differently. Fprobes (and kretprobes) has
   slots per callsite that are reserved to save the return address. This
   is fine when just a few points are traced. But users of fprobes, such
   as BPF programs, are starting to add many more locations, and this
   method does not scale.

   The function graph tracer was created to trace all functions in the
   kernel. In order to do this, when function graph tracing is started,
   every task gets its own shadow stack to hold the return address that
   is going to be traced. The function graph tracer has been updated to
   allow multiple users to use its infrastructure. Now have fprobes be
   one of those users. This will also allow for the fprobe and kretprobe
   methods to trace the return address to become obsolete. With new
   technologies like CFI that need to know about these methods of
   hijacking the return address, going toward a solution that has only
   one method of doing this will make the kernel less complex.

 - Cleanup with guard() and free() helpers

   There were several places in the code that had a lot of "goto out" in
   the error paths to either unlock a lock or free some memory that was
   allocated. But this is error prone. Convert the code over to use the
   guard() and free() helpers that let the compiler unlock locks or free
   memory when the function exits.

 - Remove disabling of interrupts in the function graph tracer

   When function graph tracer was first introduced, it could race with
   interrupts and NMIs. To prevent that race, it would disable
   interrupts and not trace NMIs. But the code has changed to allow NMIs
   and also interrupts. This change was done a long time ago, but the
   disabling of interrupts was never removed. Remove the disabling of
   interrupts in the function graph tracer is it is not needed. This
   greatly improves its performance.

 - Allow the :mod: command to enable tracing module functions on the
   kernel command line.

   The function tracer already has a way to enable functions to be
   traced in modules by writing ":mod:<module>" into set_ftrace_filter.
   That will enable either all the functions for the module if it is
   loaded, or if it is not, it will cache that command, and when the
   module is loaded that matches <module>, its functions will be
   enabled. This also allows init functions to be traced. But currently
   events do not have that feature.

   Because enabling function tracing can be done very early at boot up
   (before scheduling is enabled), the commands that can be done when
   function tracing is started is limited. Having the ":mod:" command to
   trace module functions as they are loaded is very useful. Update the
   kernel command line function filtering to allow it.

* tag 'ftrace-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits)
  ftrace: Implement :mod: cache filtering on kernel command line
  tracing: Adopt __free() and guard() for trace_fprobe.c
  bpf: Use ftrace_get_symaddr() for kprobe_multi probes
  ftrace: Add ftrace_get_symaddr to convert fentry_ip to symaddr
  Documentation: probes: Update fprobe on function-graph tracer
  selftests/ftrace: Add a test case for repeating register/unregister fprobe
  selftests: ftrace: Remove obsolate maxactive syntax check
  tracing/fprobe: Remove nr_maxactive from fprobe
  fprobe: Add fprobe_header encoding feature
  fprobe: Rewrite fprobe on function-graph tracer
  s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC
  ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC
  bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
  tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
  tracing: Add ftrace_fill_perf_regs() for perf event
  tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
  fprobe: Use ftrace_regs in fprobe exit handler
  fprobe: Use ftrace_regs in fprobe entry handler
  fgraph: Pass ftrace_regs to retfunc
  fgraph: Replace fgraph_ret_regs with ftrace_regs
  ...

1 files changed, 134 insertions, 136 deletions

diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index c62d1629cffe..b8f3c4ba309b 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -134,7 +134,7 @@ static int
 process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
 		   void *dest, void *base)
 {
-	struct pt_regs *regs = rec;
+	struct ftrace_regs *fregs = rec;
 	unsigned long val;
 	int ret;
 
@@ -142,17 +142,17 @@ retry:
 	/* 1st stage: get value from context */
 	switch (code->op) {
 	case FETCH_OP_STACK:
-		val = regs_get_kernel_stack_nth(regs, code->param);
+		val = ftrace_regs_get_kernel_stack_nth(fregs, code->param);
 		break;
 	case FETCH_OP_STACKP:
-		val = kernel_stack_pointer(regs);
+		val = ftrace_regs_get_stack_pointer(fregs);
 		break;
 	case FETCH_OP_RETVAL:
-		val = regs_return_value(regs);
+		val = ftrace_regs_get_return_value(fregs);
 		break;
 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
 	case FETCH_OP_ARG:
-		val = regs_get_kernel_argument(regs, code->param);
+		val = ftrace_regs_get_argument(fregs, code->param);
 		break;
 	case FETCH_OP_EDATA:
 		val = *(unsigned long *)((unsigned long)edata + code->offset);
@@ -175,7 +175,7 @@ NOKPROBE_SYMBOL(process_fetch_insn)
 /* function entry handler */
 static nokprobe_inline void
 __fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
-		    struct pt_regs *regs,
+		    struct ftrace_regs *fregs,
 		    struct trace_event_file *trace_file)
 {
 	struct fentry_trace_entry_head *entry;
@@ -189,41 +189,71 @@ __fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
 	if (trace_trigger_soft_disabled(trace_file))
 		return;
 
-	dsize = __get_data_size(&tf->tp, regs, NULL);
+	dsize = __get_data_size(&tf->tp, fregs, NULL);
 
 	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
 					   sizeof(*entry) + tf->tp.size + dsize);
 	if (!entry)
 		return;
 
-	fbuffer.regs = regs;
+	fbuffer.regs = ftrace_get_regs(fregs);
 	entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
 	entry->ip = entry_ip;
-	store_trace_args(&entry[1], &tf->tp, regs, NULL, sizeof(*entry), dsize);
+	store_trace_args(&entry[1], &tf->tp, fregs, NULL, sizeof(*entry), dsize);
 
 	trace_event_buffer_commit(&fbuffer);
 }
 
 static void
 fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
-		  struct pt_regs *regs)
+		  struct ftrace_regs *fregs)
 {
 	struct event_file_link *link;
 
 	trace_probe_for_each_link_rcu(link, &tf->tp)
-		__fentry_trace_func(tf, entry_ip, regs, link->file);
+		__fentry_trace_func(tf, entry_ip, fregs, link->file);
 }
 NOKPROBE_SYMBOL(fentry_trace_func);
 
+static nokprobe_inline
+void store_fprobe_entry_data(void *edata, struct trace_probe *tp, struct ftrace_regs *fregs)
+{
+	struct probe_entry_arg *earg = tp->entry_arg;
+	unsigned long val = 0;
+	int i;
+
+	if (!earg)
+		return;
+
+	for (i = 0; i < earg->size; i++) {
+		struct fetch_insn *code = &earg->code[i];
+
+		switch (code->op) {
+		case FETCH_OP_ARG:
+			val = ftrace_regs_get_argument(fregs, code->param);
+			break;
+		case FETCH_OP_ST_EDATA:
+			*(unsigned long *)((unsigned long)edata + code->offset) = val;
+			break;
+		case FETCH_OP_END:
+			goto end;
+		default:
+			break;
+		}
+	}
+end:
+	return;
+}
+
 /* function exit handler */
 static int trace_fprobe_entry_handler(struct fprobe *fp, unsigned long entry_ip,
-				unsigned long ret_ip, struct pt_regs *regs,
+				unsigned long ret_ip, struct ftrace_regs *fregs,
 				void *entry_data)
 {
 	struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
 
 	if (tf->tp.entry_arg)
-		store_trace_entry_data(entry_data, &tf->tp, regs);
+		store_fprobe_entry_data(entry_data, &tf->tp, fregs);
 
 	return 0;
 }
@@ -231,7 +261,7 @@ NOKPROBE_SYMBOL(trace_fprobe_entry_handler)
 
 static nokprobe_inline void
 __fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
-		   unsigned long ret_ip, struct pt_regs *regs,
+		   unsigned long ret_ip, struct ftrace_regs *fregs,
 		   void *entry_data, struct trace_event_file *trace_file)
 {
 	struct fexit_trace_entry_head *entry;
@@ -245,60 +275,63 @@ __fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
 	if (trace_trigger_soft_disabled(trace_file))
 		return;
 
-	dsize = __get_data_size(&tf->tp, regs, entry_data);
+	dsize = __get_data_size(&tf->tp, fregs, entry_data);
 
 	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
 					   sizeof(*entry) + tf->tp.size + dsize);
 	if (!entry)
 		return;
 
-	fbuffer.regs = regs;
+	fbuffer.regs = ftrace_get_regs(fregs);
 	entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
 	entry->func = entry_ip;
 	entry->ret_ip = ret_ip;
-	store_trace_args(&entry[1], &tf->tp, regs, entry_data, sizeof(*entry), dsize);
+	store_trace_args(&entry[1], &tf->tp, fregs, entry_data, sizeof(*entry), dsize);
 
 	trace_event_buffer_commit(&fbuffer);
 }
 
 static void
 fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
-		 unsigned long ret_ip, struct pt_regs *regs, void *entry_data)
+		 unsigned long ret_ip, struct ftrace_regs *fregs, void *entry_data)
 {
 	struct event_file_link *link;
 
 	trace_probe_for_each_link_rcu(link, &tf->tp)
-		__fexit_trace_func(tf, entry_ip, ret_ip, regs, entry_data, link->file);
+		__fexit_trace_func(tf, entry_ip, ret_ip, fregs, entry_data, link->file);
 }
 NOKPROBE_SYMBOL(fexit_trace_func);
 
 #ifdef CONFIG_PERF_EVENTS
 
 static int fentry_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
-			    struct pt_regs *regs)
+			    struct ftrace_regs *fregs)
 {
 	struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 	struct fentry_trace_entry_head *entry;
 	struct hlist_head *head;
 	int size, __size, dsize;
+	struct pt_regs *regs;
 	int rctx;
 
 	head = this_cpu_ptr(call->perf_events);
 	if (hlist_empty(head))
 		return 0;
 
-	dsize = __get_data_size(&tf->tp, regs, NULL);
+	dsize = __get_data_size(&tf->tp, fregs, NULL);
 	__size = sizeof(*entry) + tf->tp.size + dsize;
 	size = ALIGN(__size + sizeof(u32), sizeof(u64));
 	size -= sizeof(u32);
 
-	entry = perf_trace_buf_alloc(size, NULL, &rctx);
+	entry = perf_trace_buf_alloc(size, &regs, &rctx);
 	if (!entry)
 		return 0;
 
+	regs = ftrace_fill_perf_regs(fregs, regs);
+
 	entry->ip = entry_ip;
 	memset(&entry[1], 0, dsize);
-	store_trace_args(&entry[1], &tf->tp, regs, NULL, sizeof(*entry), dsize);
+	store_trace_args(&entry[1], &tf->tp, fregs, NULL, sizeof(*entry), dsize);
 	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
 			      head, NULL);
 	return 0;
@@ -307,31 +340,34 @@ NOKPROBE_SYMBOL(fentry_perf_func);
 
 static void
 fexit_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
-		unsigned long ret_ip, struct pt_regs *regs,
+		unsigned long ret_ip, struct ftrace_regs *fregs,
 		void *entry_data)
 {
 	struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 	struct fexit_trace_entry_head *entry;
 	struct hlist_head *head;
 	int size, __size, dsize;
+	struct pt_regs *regs;
 	int rctx;
 
 	head = this_cpu_ptr(call->perf_events);
 	if (hlist_empty(head))
 		return;
 
-	dsize = __get_data_size(&tf->tp, regs, entry_data);
+	dsize = __get_data_size(&tf->tp, fregs, entry_data);
 	__size = sizeof(*entry) + tf->tp.size + dsize;
 	size = ALIGN(__size + sizeof(u32), sizeof(u64));
 	size -= sizeof(u32);
 
-	entry = perf_trace_buf_alloc(size, NULL, &rctx);
+	entry = perf_trace_buf_alloc(size, &regs, &rctx);
 	if (!entry)
 		return;
 
+	regs = ftrace_fill_perf_regs(fregs, regs);
+
 	entry->func = entry_ip;
 	entry->ret_ip = ret_ip;
-	store_trace_args(&entry[1], &tf->tp, regs, entry_data, sizeof(*entry), dsize);
+	store_trace_args(&entry[1], &tf->tp, fregs, entry_data, sizeof(*entry), dsize);
 	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
 			      head, NULL);
 }
@@ -339,33 +375,34 @@ NOKPROBE_SYMBOL(fexit_perf_func);
 #endif	/* CONFIG_PERF_EVENTS */
 
 static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
-			     unsigned long ret_ip, struct pt_regs *regs,
+			     unsigned long ret_ip, struct ftrace_regs *fregs,
 			     void *entry_data)
 {
 	struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
 	int ret = 0;
 
 	if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
-		fentry_trace_func(tf, entry_ip, regs);
+		fentry_trace_func(tf, entry_ip, fregs);
+
 #ifdef CONFIG_PERF_EVENTS
 	if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
-		ret = fentry_perf_func(tf, entry_ip, regs);
+		ret = fentry_perf_func(tf, entry_ip, fregs);
 #endif
 	return ret;
 }
 NOKPROBE_SYMBOL(fentry_dispatcher);
 
 static void fexit_dispatcher(struct fprobe *fp, unsigned long entry_ip,
-			     unsigned long ret_ip, struct pt_regs *regs,
+			     unsigned long ret_ip, struct ftrace_regs *fregs,
 			     void *entry_data)
 {
 	struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
 
 	if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
-		fexit_trace_func(tf, entry_ip, ret_ip, regs, entry_data);
+		fexit_trace_func(tf, entry_ip, ret_ip, fregs, entry_data);
 #ifdef CONFIG_PERF_EVENTS
 	if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
-		fexit_perf_func(tf, entry_ip, ret_ip, regs, entry_data);
+		fexit_perf_func(tf, entry_ip, ret_ip, fregs, entry_data);
 #endif
 }
 NOKPROBE_SYMBOL(fexit_dispatcher);
@@ -379,6 +416,9 @@ static void free_trace_fprobe(struct trace_fprobe *tf)
 	}
 }
 
+/* Since alloc_trace_fprobe() can return error, check the pointer is ERR too. */
+DEFINE_FREE(free_trace_fprobe, struct trace_fprobe *, if (!IS_ERR_OR_NULL(_T)) free_trace_fprobe(_T))
+
 /*
  * Allocate new trace_probe and initialize it (including fprobe).
  */
@@ -387,10 +427,9 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 					       const char *symbol,
 					       struct tracepoint *tpoint,
 					       struct module *mod,
-					       int maxactive,
 					       int nargs, bool is_return)
 {
-	struct trace_fprobe *tf;
+	struct trace_fprobe *tf __free(free_trace_fprobe) = NULL;
 	int ret = -ENOMEM;
 
 	tf = kzalloc(struct_size(tf, tp.args, nargs), GFP_KERNEL);
@@ -399,7 +438,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 
 	tf->symbol = kstrdup(symbol, GFP_KERNEL);
 	if (!tf->symbol)
-		goto error;
+		return ERR_PTR(-ENOMEM);
 
 	if (is_return)
 		tf->fp.exit_handler = fexit_dispatcher;
@@ -408,17 +447,13 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 
 	tf->tpoint = tpoint;
 	tf->mod = mod;
-	tf->fp.nr_maxactive = maxactive;
 
 	ret = trace_probe_init(&tf->tp, event, group, false, nargs);
 	if (ret < 0)
-		goto error;
+		return ERR_PTR(ret);
 
 	dyn_event_init(&tf->devent, &trace_fprobe_ops);
-	return tf;
-error:
-	free_trace_fprobe(tf);
-	return ERR_PTR(ret);
+	return_ptr(tf);
 }
 
 static struct trace_fprobe *find_trace_fprobe(const char *event,
@@ -845,14 +880,12 @@ static int register_trace_fprobe(struct trace_fprobe *tf)
 	struct trace_fprobe *old_tf;
 	int ret;
 
-	mutex_lock(&event_mutex);
+	guard(mutex)(&event_mutex);
 
 	old_tf = find_trace_fprobe(trace_probe_name(&tf->tp),
 				   trace_probe_group_name(&tf->tp));
-	if (old_tf) {
-		ret = append_trace_fprobe(tf, old_tf);
-		goto end;
-	}
+	if (old_tf)
+		return append_trace_fprobe(tf, old_tf);
 
 	/* Register new event */
 	ret = register_fprobe_event(tf);
@@ -862,7 +895,7 @@ static int register_trace_fprobe(struct trace_fprobe *tf)
 			trace_probe_log_err(0, EVENT_EXIST);
 		} else
 			pr_warn("Failed to register probe event(%d)\n", ret);
-		goto end;
+		return ret;
 	}
 
 	/* Register fprobe */
@@ -872,8 +905,6 @@ static int register_trace_fprobe(struct trace_fprobe *tf)
 	else
 		dyn_event_add(&tf->devent, trace_probe_event_call(&tf->tp));
 
-end:
-	mutex_unlock(&event_mutex);
 	return ret;
 }
 
@@ -1034,7 +1065,10 @@ static int parse_symbol_and_return(int argc, const char *argv[],
 	return 0;
 }
 
-static int __trace_fprobe_create(int argc, const char *argv[])
+DEFINE_FREE(module_put, struct module *, if (_T) module_put(_T))
+
+static int trace_fprobe_create_internal(int argc, const char *argv[],
+					struct traceprobe_parse_context *ctx)
 {
 	/*
 	 * Argument syntax:
@@ -1060,24 +1094,20 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	 * Type of args:
 	 *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 	 */
-	struct trace_fprobe *tf = NULL;
-	int i, len, new_argc = 0, ret = 0;
+	struct trace_fprobe *tf __free(free_trace_fprobe) = NULL;
+	int i, new_argc = 0, ret = 0;
 	bool is_return = false;
-	char *symbol = NULL;
+	char *symbol __free(kfree) = NULL;
 	const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
-	const char **new_argv = NULL;
-	int maxactive = 0;
+	const char **new_argv __free(kfree) = NULL;
 	char buf[MAX_EVENT_NAME_LEN];
 	char gbuf[MAX_EVENT_NAME_LEN];
 	char sbuf[KSYM_NAME_LEN];
 	char abuf[MAX_BTF_ARGS_LEN];
-	char *dbuf = NULL;
+	char *dbuf __free(kfree) = NULL;
 	bool is_tracepoint = false;
-	struct module *tp_mod = NULL;
+	struct module *tp_mod __free(module_put) = NULL;
 	struct tracepoint *tpoint = NULL;
-	struct traceprobe_parse_context ctx = {
-		.flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
-	};
 
 	if ((argv[0][0] != 'f' && argv[0][0] != 't') || argc < 2)
 		return -ECANCELED;
@@ -1087,35 +1117,13 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 		group = TRACEPOINT_EVENT_SYSTEM;
 	}
 
-	trace_probe_log_init("trace_fprobe", argc, argv);
-
-	event = strchr(&argv[0][1], ':');
-	if (event)
-		event++;
-
-	if (isdigit(argv[0][1])) {
-		if (event)
-			len = event - &argv[0][1] - 1;
-		else
-			len = strlen(&argv[0][1]);
-		if (len > MAX_EVENT_NAME_LEN - 1) {
-			trace_probe_log_err(1, BAD_MAXACT);
-			goto parse_error;
-		}
-		memcpy(buf, &argv[0][1], len);
-		buf[len] = '\0';
-		ret = kstrtouint(buf, 0, &maxactive);
-		if (ret || !maxactive) {
+	if (argv[0][1] != '\0') {
+		if (argv[0][1] != ':') {
+			trace_probe_log_set_index(0);
 			trace_probe_log_err(1, BAD_MAXACT);
-			goto parse_error;
-		}
-		/* fprobe rethook instances are iterated over via a list. The
-		 * maximum should stay reasonable.
-		 */
-		if (maxactive > RETHOOK_MAXACTIVE_MAX) {
-			trace_probe_log_err(1, MAXACT_TOO_BIG);
-			goto parse_error;
+			return -EINVAL;
 		}
+		event = &argv[0][2];
 	}
 
 	trace_probe_log_set_index(1);
@@ -1123,20 +1131,14 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	/* a symbol(or tracepoint) must be specified */
 	ret = parse_symbol_and_return(argc, argv, &symbol, &is_return, is_tracepoint);
 	if (ret < 0)
-		goto parse_error;
-
-	if (!is_return && maxactive) {
-		trace_probe_log_set_index(0);
-		trace_probe_log_err(1, BAD_MAXACT_TYPE);
-		goto parse_error;
-	}
+		return -EINVAL;
 
 	trace_probe_log_set_index(0);
 	if (event) {
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
 						  event - argv[0]);
 		if (ret)
-			goto parse_error;
+			return -EINVAL;
 	}
 
 	if (!event) {
@@ -1152,67 +1154,62 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	}
 
 	if (is_return)
-		ctx.flags |= TPARG_FL_RETURN;
+		ctx->flags |= TPARG_FL_RETURN;
 	else
-		ctx.flags |= TPARG_FL_FENTRY;
+		ctx->flags |= TPARG_FL_FENTRY;
 
 	if (is_tracepoint) {
-		ctx.flags |= TPARG_FL_TPOINT;
+		ctx->flags |= TPARG_FL_TPOINT;
 		tpoint = find_tracepoint(symbol, &tp_mod);
 		if (tpoint) {
-			ctx.funcname = kallsyms_lookup(
+			ctx->funcname = kallsyms_lookup(
 				(unsigned long)tpoint->probestub,
 				NULL, NULL, NULL, sbuf);
 		} else if (IS_ENABLED(CONFIG_MODULES)) {
 				/* This *may* be loaded afterwards */
 				tpoint = TRACEPOINT_STUB;
-				ctx.funcname = symbol;
+				ctx->funcname = symbol;
 		} else {
 			trace_probe_log_set_index(1);
 			trace_probe_log_err(0, NO_TRACEPOINT);
-			goto parse_error;
+			return -EINVAL;
 		}
 	} else
-		ctx.funcname = symbol;
+		ctx->funcname = symbol;
 
 	argc -= 2; argv += 2;
 	new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
-					       abuf, MAX_BTF_ARGS_LEN, &ctx);
-	if (IS_ERR(new_argv)) {
-		ret = PTR_ERR(new_argv);
-		new_argv = NULL;
-		goto out;
-	}
+					       abuf, MAX_BTF_ARGS_LEN, ctx);
+	if (IS_ERR(new_argv))
+		return PTR_ERR(new_argv);
 	if (new_argv) {
 		argc = new_argc;
 		argv = new_argv;
 	}
-	if (argc > MAX_TRACE_ARGS) {
-		ret = -E2BIG;
-		goto out;
-	}
+	if (argc > MAX_TRACE_ARGS)
+		return -E2BIG;
 
 	ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
 	if (ret)
-		goto out;
+		return ret;
 
 	/* setup a probe */
 	tf = alloc_trace_fprobe(group, event, symbol, tpoint, tp_mod,
-				maxactive, argc, is_return);
+				argc, is_return);
 	if (IS_ERR(tf)) {
 		ret = PTR_ERR(tf);
 		/* This must return -ENOMEM, else there is a bug */
 		WARN_ON_ONCE(ret != -ENOMEM);
-		goto out;	/* We know tf is not allocated */
+		return ret;
 	}
 
 	/* parse arguments */
 	for (i = 0; i < argc; i++) {
 		trace_probe_log_set_index(i + 2);
-		ctx.offset = 0;
-		ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx);
+		ctx->offset = 0;
+		ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], ctx);
 		if (ret)
-			goto error;	/* This can be -ENOMEM */
+			return ret;	/* This can be -ENOMEM */
 	}
 
 	if (is_return && tf->tp.entry_arg) {
@@ -1223,7 +1220,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	ret = traceprobe_set_print_fmt(&tf->tp,
 			is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL);
 	if (ret < 0)
-		goto error;
+		return ret;
 
 	ret = register_trace_fprobe(tf);
 	if (ret) {
@@ -1234,29 +1231,32 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 			trace_probe_log_err(0, BAD_PROBE_ADDR);
 		else if (ret != -ENOMEM && ret != -EEXIST)
 			trace_probe_log_err(0, FAIL_REG_PROBE);
-		goto error;
+		return -EINVAL;
 	}
 
-out:
-	if (tp_mod)
-		module_put(tp_mod);
+	/* 'tf' is successfully registered. To avoid freeing, assign NULL. */
+	tf = NULL;
+
+	return 0;
+}
+
+static int trace_fprobe_create_cb(int argc, const char *argv[])
+{
+	struct traceprobe_parse_context ctx = {
+		.flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
+	};
+	int ret;
+
+	trace_probe_log_init("trace_fprobe", argc, argv);
+	ret = trace_fprobe_create_internal(argc, argv, &ctx);
 	traceprobe_finish_parse(&ctx);
 	trace_probe_log_clear();
-	kfree(new_argv);
-	kfree(symbol);
-	kfree(dbuf);
 	return ret;
-
-parse_error:
-	ret = -EINVAL;
-error:
-	free_trace_fprobe(tf);
-	goto out;
 }
 
 static int trace_fprobe_create(const char *raw_command)
 {
-	return trace_probe_create(raw_command, __trace_fprobe_create);
+	return trace_probe_create(raw_command, trace_fprobe_create_cb);
 }
 
 static int trace_fprobe_release(struct dyn_event *ev)
@@ -1278,8 +1278,6 @@ static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev)
 		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),
 				trace_probe_name(&tf->tp));