Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1231 insertions, 0 deletions

diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
new file mode 100644
index 0000000000..7d2ddbcfa3
--- /dev/null
+++ b/kernel/trace/trace_fprobe.c
@@ -0,0 +1,1231 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Fprobe-based tracing events
+ * Copyright (C) 2022 Google LLC.
+ */
+#define pr_fmt(fmt)	"trace_fprobe: " fmt
+
+#include <linux/fprobe.h>
+#include <linux/module.h>
+#include <linux/rculist.h>
+#include <linux/security.h>
+#include <linux/tracepoint.h>
+#include <linux/uaccess.h>
+
+#include "trace_dynevent.h"
+#include "trace_probe.h"
+#include "trace_probe_kernel.h"
+#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);
+static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev);
+static int trace_fprobe_release(struct dyn_event *ev);
+static bool trace_fprobe_is_busy(struct dyn_event *ev);
+static bool trace_fprobe_match(const char *system, const char *event,
+			int argc, const char **argv, struct dyn_event *ev);
+
+static struct dyn_event_operations trace_fprobe_ops = {
+	.create = trace_fprobe_create,
+	.show = trace_fprobe_show,
+	.is_busy = trace_fprobe_is_busy,
+	.free = trace_fprobe_release,
+	.match = trace_fprobe_match,
+};
+
+/*
+ * Fprobe event core functions
+ */
+struct trace_fprobe {
+	struct dyn_event	devent;
+	struct fprobe		fp;
+	const char		*symbol;
+	struct tracepoint	*tpoint;
+	struct module		*mod;
+	struct trace_probe	tp;
+};
+
+static bool is_trace_fprobe(struct dyn_event *ev)
+{
+	return ev->ops == &trace_fprobe_ops;
+}
+
+static struct trace_fprobe *to_trace_fprobe(struct dyn_event *ev)
+{
+	return container_of(ev, struct trace_fprobe, devent);
+}
+
+/**
+ * for_each_trace_fprobe - iterate over the trace_fprobe list
+ * @pos:	the struct trace_fprobe * for each entry
+ * @dpos:	the struct dyn_event * to use as a loop cursor
+ */
+#define for_each_trace_fprobe(pos, dpos)	\
+	for_each_dyn_event(dpos)		\
+		if (is_trace_fprobe(dpos) && (pos = to_trace_fprobe(dpos)))
+
+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";
+}
+
+static bool trace_fprobe_is_busy(struct dyn_event *ev)
+{
+	struct trace_fprobe *tf = to_trace_fprobe(ev);
+
+	return trace_probe_is_enabled(&tf->tp);
+}
+
+static bool trace_fprobe_match_command_head(struct trace_fprobe *tf,
+					    int argc, const char **argv)
+{
+	char buf[MAX_ARGSTR_LEN + 1];
+
+	if (!argc)
+		return true;
+
+	snprintf(buf, sizeof(buf), "%s", trace_fprobe_symbol(tf));
+	if (strcmp(buf, argv[0]))
+		return false;
+	argc--; argv++;
+
+	return trace_probe_match_command_args(&tf->tp, argc, argv);
+}
+
+static bool trace_fprobe_match(const char *system, const char *event,
+			int argc, const char **argv, struct dyn_event *ev)
+{
+	struct trace_fprobe *tf = to_trace_fprobe(ev);
+
+	if (event[0] != '\0' && strcmp(trace_probe_name(&tf->tp), event))
+		return false;
+
+	if (system && strcmp(trace_probe_group_name(&tf->tp), system))
+		return false;
+
+	return trace_fprobe_match_command_head(tf, argc, argv);
+}
+
+static bool trace_fprobe_is_registered(struct trace_fprobe *tf)
+{
+	return fprobe_is_registered(&tf->fp);
+}
+
+/*
+ * Note that we don't verify the fetch_insn code, since it does not come
+ * from user space.
+ */
+static int
+process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
+		   void *base)
+{
+	struct pt_regs *regs = rec;
+	unsigned long val;
+	int ret;
+
+retry:
+	/* 1st stage: get value from context */
+	switch (code->op) {
+	case FETCH_OP_STACK:
+		val = regs_get_kernel_stack_nth(regs, code->param);
+		break;
+	case FETCH_OP_STACKP:
+		val = kernel_stack_pointer(regs);
+		break;
+	case FETCH_OP_RETVAL:
+		val = regs_return_value(regs);
+		break;
+#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
+	case FETCH_OP_ARG:
+		val = regs_get_kernel_argument(regs, code->param);
+		break;
+#endif
+	case FETCH_NOP_SYMBOL:	/* Ignore a place holder */
+		code++;
+		goto retry;
+	default:
+		ret = process_common_fetch_insn(code, &val);
+		if (ret < 0)
+			return ret;
+	}
+	code++;
+
+	return process_fetch_insn_bottom(code, val, dest, base);
+}
+NOKPROBE_SYMBOL(process_fetch_insn)
+
+/* function entry handler */
+static nokprobe_inline void
+__fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
+		    struct pt_regs *regs,
+		    struct trace_event_file *trace_file)
+{
+	struct fentry_trace_entry_head *entry;
+	struct trace_event_call *call = trace_probe_event_call(&tf->tp);
+	struct trace_event_buffer fbuffer;
+	int dsize;
+
+	if (WARN_ON_ONCE(call != trace_file->event_call))
+		return;
+
+	if (trace_trigger_soft_disabled(trace_file))
+		return;
+
+	dsize = __get_data_size(&tf->tp, regs);
+
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+					   sizeof(*entry) + tf->tp.size + dsize);
+	if (!entry)
+		return;
+
+	fbuffer.regs = regs;
+	entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
+	entry->ip = entry_ip;
+	store_trace_args(&entry[1], &tf->tp, regs, 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 event_file_link *link;
+
+	trace_probe_for_each_link_rcu(link, &tf->tp)
+		__fentry_trace_func(tf, entry_ip, regs, link->file);
+}
+NOKPROBE_SYMBOL(fentry_trace_func);
+
+/* Kretprobe handler */
+static nokprobe_inline void
+__fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
+		   unsigned long ret_ip, struct pt_regs *regs,
+		   struct trace_event_file *trace_file)
+{
+	struct fexit_trace_entry_head *entry;
+	struct trace_event_buffer fbuffer;
+	struct trace_event_call *call = trace_probe_event_call(&tf->tp);
+	int dsize;
+
+	if (WARN_ON_ONCE(call != trace_file->event_call))
+		return;
+
+	if (trace_trigger_soft_disabled(trace_file))
+		return;
+
+	dsize = __get_data_size(&tf->tp, regs);
+
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+					   sizeof(*entry) + tf->tp.size + dsize);
+	if (!entry)
+		return;
+
+	fbuffer.regs = regs;
+	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, 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)
+{
+	struct event_file_link *link;
+
+	trace_probe_for_each_link_rcu(link, &tf->tp)
+		__fexit_trace_func(tf, entry_ip, ret_ip, regs, 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 trace_event_call *call = trace_probe_event_call(&tf->tp);
+	struct fentry_trace_entry_head *entry;
+	struct hlist_head *head;
+	int size, __size, dsize;
+	int rctx;
+
+	head = this_cpu_ptr(call->perf_events);
+	if (hlist_empty(head))
+		return 0;
+
+	dsize = __get_data_size(&tf->tp, regs);
+	__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);
+	if (!entry)
+		return 0;
+
+	entry->ip = entry_ip;
+	memset(&entry[1], 0, dsize);
+	store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
+			      head, NULL);
+	return 0;
+}
+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)
+{
+	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;
+	int rctx;
+
+	head = this_cpu_ptr(call->perf_events);
+	if (hlist_empty(head))
+		return;
+
+	dsize = __get_data_size(&tf->tp, regs);
+	__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);
+	if (!entry)
+		return;
+
+	entry->func = entry_ip;
+	entry->ret_ip = ret_ip;
+	store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
+			      head, NULL);
+}
+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,
+			     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);
+#ifdef CONFIG_PERF_EVENTS
+	if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
+		ret = fentry_perf_func(tf, entry_ip, regs);
+#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,
+			     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);
+#ifdef CONFIG_PERF_EVENTS
+	if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
+		fexit_perf_func(tf, entry_ip, ret_ip, regs);
+#endif
+}
+NOKPROBE_SYMBOL(fexit_dispatcher);
+
+static void free_trace_fprobe(struct trace_fprobe *tf)
+{
+	if (tf) {
+		trace_probe_cleanup(&tf->tp);
+		kfree(tf->symbol);
+		kfree(tf);
+	}
+}
+
+/*
+ * Allocate new trace_probe and initialize it (including fprobe).
+ */
+static struct trace_fprobe *alloc_trace_fprobe(const char *group,
+					       const char *event,
+					       const char *symbol,
+					       struct tracepoint *tpoint,
+					       int maxactive,
+					       int nargs, bool is_return)
+{
+	struct trace_fprobe *tf;
+	int ret = -ENOMEM;
+
+	tf = kzalloc(struct_size(tf, tp.args, nargs), GFP_KERNEL);
+	if (!tf)
+		return ERR_PTR(ret);
+
+	tf->symbol = kstrdup(symbol, GFP_KERNEL);
+	if (!tf->symbol)
+		goto error;
+
+	if (is_return)
+		tf->fp.exit_handler = fexit_dispatcher;
+	else
+		tf->fp.entry_handler = fentry_dispatcher;
+
+	tf->tpoint = tpoint;
+	tf->fp.nr_maxactive = maxactive;
+
+	ret = trace_probe_init(&tf->tp, event, group, false);
+	if (ret < 0)
+		goto error;
+
+	dyn_event_init(&tf->devent, &trace_fprobe_ops);
+	return tf;
+error:
+	free_trace_fprobe(tf);
+	return ERR_PTR(ret);
+}
+
+static struct trace_fprobe *find_trace_fprobe(const char *event,
+					      const char *group)
+{
+	struct dyn_event *pos;
+	struct trace_fprobe *tf;
+
+	for_each_trace_fprobe(tf, pos)
+		if (strcmp(trace_probe_name(&tf->tp), event) == 0 &&
+		    strcmp(trace_probe_group_name(&tf->tp), group) == 0)
+			return tf;
+	return NULL;
+}
+
+static inline int __enable_trace_fprobe(struct trace_fprobe *tf)
+{
+	if (trace_fprobe_is_registered(tf))
+		enable_fprobe(&tf->fp);
+
+	return 0;
+}
+
+static void __disable_trace_fprobe(struct trace_probe *tp)
+{
+	struct trace_fprobe *tf;
+
+	list_for_each_entry(tf, trace_probe_probe_list(tp), tp.list) {
+		if (!trace_fprobe_is_registered(tf))
+			continue;
+		disable_fprobe(&tf->fp);
+	}
+}
+
+/*
+ * Enable trace_probe
+ * if the file is NULL, enable "perf" handler, or enable "trace" handler.
+ */
+static int enable_trace_fprobe(struct trace_event_call *call,
+			       struct trace_event_file *file)
+{
+	struct trace_probe *tp;
+	struct trace_fprobe *tf;
+	bool enabled;
+	int ret = 0;
+
+	tp = trace_probe_primary_from_call(call);
+	if (WARN_ON_ONCE(!tp))
+		return -ENODEV;
+	enabled = trace_probe_is_enabled(tp);
+
+	/* This also changes "enabled" state */
+	if (file) {
+		ret = trace_probe_add_file(tp, file);
+		if (ret)
+			return ret;
+	} else
+		trace_probe_set_flag(tp, TP_FLAG_PROFILE);
+
+	if (!enabled) {
+		list_for_each_entry(tf, trace_probe_probe_list(tp), tp.list) {
+			/* TODO: check the fprobe is gone */
+			__enable_trace_fprobe(tf);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Disable trace_probe
+ * if the file is NULL, disable "perf" handler, or disable "trace" handler.
+ */
+static int disable_trace_fprobe(struct trace_event_call *call,
+				struct trace_event_file *file)
+{
+	struct trace_probe *tp;
+
+	tp = trace_probe_primary_from_call(call);
+	if (WARN_ON_ONCE(!tp))
+		return -ENODEV;
+
+	if (file) {
+		if (!trace_probe_get_file_link(tp, file))
+			return -ENOENT;
+		if (!trace_probe_has_single_file(tp))
+			goto out;
+		trace_probe_clear_flag(tp, TP_FLAG_TRACE);
+	} else
+		trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
+
+	if (!trace_probe_is_enabled(tp))
+		__disable_trace_fprobe(tp);
+
+ out:
+	if (file)
+		/*
+		 * Synchronization is done in below function. For perf event,
+		 * file == NULL and perf_trace_event_unreg() calls
+		 * tracepoint_synchronize_unregister() to ensure synchronize
+		 * event. We don't need to care about it.
+		 */
+		trace_probe_remove_file(tp, file);
+
+	return 0;
+}
+
+/* Event entry printers */
+static enum print_line_t
+print_fentry_event(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
+{
+	struct fentry_trace_entry_head *field;
+	struct trace_seq *s = &iter->seq;
+	struct trace_probe *tp;
+
+	field = (struct fentry_trace_entry_head *)iter->ent;
+	tp = trace_probe_primary_from_call(
+		container_of(event, struct trace_event_call, event));
+	if (WARN_ON_ONCE(!tp))
+		goto out;
+
+	trace_seq_printf(s, "%s: (", trace_probe_name(tp));
+
+	if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+		goto out;
+
+	trace_seq_putc(s, ')');
+
+	if (trace_probe_print_args(s, tp->args, tp->nr_args,
+			     (u8 *)&field[1], field) < 0)
+		goto out;
+
+	trace_seq_putc(s, '\n');
+ out:
+	return trace_handle_return(s);
+}
+
+static enum print_line_t
+print_fexit_event(struct trace_iterator *iter, int flags,
+		  struct trace_event *event)
+{
+	struct fexit_trace_entry_head *field;
+	struct trace_seq *s = &iter->seq;
+	struct trace_probe *tp;
+
+	field = (struct fexit_trace_entry_head *)iter->ent;
+	tp = trace_probe_primary_from_call(
+		container_of(event, struct trace_event_call, event));
+	if (WARN_ON_ONCE(!tp))
+		goto out;
+
+	trace_seq_printf(s, "%s: (", trace_probe_name(tp));
+
+	if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
+		goto out;
+
+	trace_seq_puts(s, " <- ");
+
+	if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
+		goto out;
+
+	trace_seq_putc(s, ')');
+
+	if (trace_probe_print_args(s, tp->args, tp->nr_args,
+			     (u8 *)&field[1], field) < 0)
+		goto out;
+
+	trace_seq_putc(s, '\n');
+
+ out:
+	return trace_handle_return(s);
+}
+
+static int fentry_event_define_fields(struct trace_event_call *event_call)
+{
+	int ret;
+	struct fentry_trace_entry_head field;
+	struct trace_probe *tp;
+
+	tp = trace_probe_primary_from_call(event_call);
+	if (WARN_ON_ONCE(!tp))
+		return -ENOENT;
+
+	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+
+	return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
+}
+
+static int fexit_event_define_fields(struct trace_event_call *event_call)
+{
+	int ret;
+	struct fexit_trace_entry_head field;
+	struct trace_probe *tp;
+
+	tp = trace_probe_primary_from_call(event_call);
+	if (WARN_ON_ONCE(!tp))
+		return -ENOENT;
+
+	DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
+	DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
+
+	return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
+}
+
+static struct trace_event_functions fentry_funcs = {
+	.trace		= print_fentry_event
+};
+
+static struct trace_event_functions fexit_funcs = {
+	.trace		= print_fexit_event
+};
+
+static struct trace_event_fields fentry_fields_array[] = {
+	{ .type = TRACE_FUNCTION_TYPE,
+	  .define_fields = fentry_event_define_fields },
+	{}
+};
+
+static struct trace_event_fields fexit_fields_array[] = {
+	{ .type = TRACE_FUNCTION_TYPE,
+	  .define_fields = fexit_event_define_fields },
+	{}
+};
+
+static int fprobe_register(struct trace_event_call *event,
+			   enum trace_reg type, void *data);
+
+static inline void init_trace_event_call(struct trace_fprobe *tf)
+{
+	struct trace_event_call *call = trace_probe_event_call(&tf->tp);
+
+	if (trace_fprobe_is_return(tf)) {
+		call->event.funcs = &fexit_funcs;
+		call->class->fields_array = fexit_fields_array;
+	} else {
+		call->event.funcs = &fentry_funcs;
+		call->class->fields_array = fentry_fields_array;
+	}
+
+	call->flags = TRACE_EVENT_FL_FPROBE;
+	call->class->reg = fprobe_register;
+}
+
+static int register_fprobe_event(struct trace_fprobe *tf)
+{
+	init_trace_event_call(tf);
+
+	return trace_probe_register_event_call(&tf->tp);
+}
+
+static int unregister_fprobe_event(struct trace_fprobe *tf)
+{
+	return trace_probe_unregister_event_call(&tf->tp);
+}
+
+/* Internal register function - just handle fprobe and flags */
+static int __register_trace_fprobe(struct trace_fprobe *tf)
+{
+	int i, ret;
+
+	/* Should we need new LOCKDOWN flag for fprobe? */
+	ret = security_locked_down(LOCKDOWN_KPROBES);
+	if (ret)
+		return ret;
+
+	if (trace_fprobe_is_registered(tf))
+		return -EINVAL;
+
+	for (i = 0; i < tf->tp.nr_args; i++) {
+		ret = traceprobe_update_arg(&tf->tp.args[i]);
+		if (ret)
+			return ret;
+	}
+
+	/* Set/clear disabled flag according to tp->flag */
+	if (trace_probe_is_enabled(&tf->tp))
+		tf->fp.flags &= ~FPROBE_FL_DISABLED;
+	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);
+}
+
+/* Internal unregister function - just handle fprobe and flags */
+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;
+		}
+	}
+}
+
+/* TODO: make this trace_*probe common function */
+/* Unregister a trace_probe and probe_event */
+static int unregister_trace_fprobe(struct trace_fprobe *tf)
+{
+	/* If other probes are on the event, just unregister fprobe */
+	if (trace_probe_has_sibling(&tf->tp))
+		goto unreg;
+
+	/* Enabled event can not be unregistered */
+	if (trace_probe_is_enabled(&tf->tp))
+		return -EBUSY;
+
+	/* If there's a reference to the dynamic event */
+	if (trace_event_dyn_busy(trace_probe_event_call(&tf->tp)))
+		return -EBUSY;
+
+	/* Will fail if probe is being used by ftrace or perf */
+	if (unregister_fprobe_event(tf))
+		return -EBUSY;
+
+unreg:
+	__unregister_trace_fprobe(tf);
+	dyn_event_remove(&tf->devent);
+	trace_probe_unlink(&tf->tp);
+
+	return 0;
+}
+
+static bool trace_fprobe_has_same_fprobe(struct trace_fprobe *orig,
+					 struct trace_fprobe *comp)
+{
+	struct trace_probe_event *tpe = orig->tp.event;
+	int i;
+
+	list_for_each_entry(orig, &tpe->probes, tp.list) {
+		if (strcmp(trace_fprobe_symbol(orig),
+			   trace_fprobe_symbol(comp)))
+			continue;
+
+		/*
+		 * trace_probe_compare_arg_type() ensured that nr_args and
+		 * each argument name and type are same. Let's compare comm.
+		 */
+		for (i = 0; i < orig->tp.nr_args; i++) {
+			if (strcmp(orig->tp.args[i].comm,
+				   comp->tp.args[i].comm))
+				break;
+		}
+
+		if (i == orig->tp.nr_args)
+			return true;
+	}
+
+	return false;
+}
+
+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) ||
+	    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;
+	}
+	ret = trace_probe_compare_arg_type(&tf->tp, &to->tp);
+	if (ret) {
+		/* Note that argument starts index = 2 */
+		trace_probe_log_set_index(ret + 1);
+		trace_probe_log_err(0, DIFF_ARG_TYPE);
+		return -EEXIST;
+	}
+	if (trace_fprobe_has_same_fprobe(to, tf)) {
+		trace_probe_log_set_index(0);
+		trace_probe_log_err(0, SAME_PROBE);
+		return -EEXIST;
+	}
+
+	/* Append to existing event */
+	ret = trace_probe_append(&tf->tp, &to->tp);
+	if (ret)
+		return ret;
+
+	ret = __register_trace_fprobe(tf);
+	if (ret)
+		trace_probe_unlink(&tf->tp);
+	else
+		dyn_event_add(&tf->devent, trace_probe_event_call(&tf->tp));
+
+	return ret;
+}
+
+/* Register a trace_probe and probe_event */
+static int register_trace_fprobe(struct trace_fprobe *tf)
+{
+	struct trace_fprobe *old_tf;
+	int ret;
+
+	mutex_lock(&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;
+	}
+
+	/* Register new event */
+	ret = register_fprobe_event(tf);
+	if (ret) {
+		if (ret == -EEXIST) {
+			trace_probe_log_set_index(0);
+			trace_probe_log_err(0, EVENT_EXIST);
+		} else
+			pr_warn("Failed to register probe event(%d)\n", ret);
+		goto end;
+	}
+
+	/* Register fprobe */
+	ret = __register_trace_fprobe(tf);
+	if (ret < 0)
+		unregister_fprobe_event(tf);
+	else
+		dyn_event_add(&tf->devent, trace_probe_event_call(&tf->tp));
+
+end:
+	mutex_unlock(&event_mutex);
+	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 parse_symbol_and_return(int argc, const char *argv[],
+				   char **symbol, bool *is_return,
+				   bool is_tracepoint)
+{
+	char *tmp = strchr(argv[1], '%');
+	int i;
+
+	if (tmp) {
+		int len = tmp - argv[1];
+
+		if (!is_tracepoint && !strcmp(tmp, "%return")) {
+			*is_return = true;
+		} else {
+			trace_probe_log_err(len, BAD_ADDR_SUFFIX);
+			return -EINVAL;
+		}
+		*symbol = kmemdup_nul(argv[1], len, GFP_KERNEL);
+	} else
+		*symbol = kstrdup(argv[1], GFP_KERNEL);
+	if (!*symbol)
+		return -ENOMEM;
+
+	if (*is_return)
+		return 0;
+
+	/* If there is $retval, this should be a return fprobe. */
+	for (i = 2; i < argc; i++) {
+		tmp = strstr(argv[i], "$retval");
+		if (tmp && !isalnum(tmp[7]) && tmp[7] != '_') {
+			if (is_tracepoint) {
+				trace_probe_log_set_index(i);
+				trace_probe_log_err(tmp - argv[i], RETVAL_ON_PROBE);
+				return -EINVAL;
+			}
+			*is_return = true;
+			break;
+		}
+	}
+	return 0;
+}
+
+static int __trace_fprobe_create(int argc, const char *argv[])
+{
+	/*
+	 * Argument syntax:
+	 *  - Add fentry probe:
+	 *      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
+	 *  $stack	: fetch stack address
+	 *  $stackN	: fetch Nth entry of stack (N:0-)
+	 *  $argN	: fetch Nth argument (N:1-)
+	 *  $comm       : fetch current task comm
+	 *  @ADDR	: fetch memory at ADDR (ADDR should be in kernel)
+	 *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
+	 * Dereferencing memory fetch:
+	 *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
+	 * Alias name of args:
+	 *  NAME=FETCHARG : set NAME as alias of FETCHARG.
+	 * Type of args:
+	 *  FETCHARG:TYPE : use TYPE instead of unsigned long.
+	 */
+	struct trace_fprobe *tf = NULL;
+	int i, len, new_argc = 0, ret = 0;
+	bool is_return = false;
+	char *symbol = NULL;
+	const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
+	const char **new_argv = NULL;
+	int maxactive = 0;
+	char buf[MAX_EVENT_NAME_LEN];
+	char gbuf[MAX_EVENT_NAME_LEN];
+	char sbuf[KSYM_NAME_LEN];
+	char abuf[MAX_BTF_ARGS_LEN];
+	bool is_tracepoint = false;
+	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;
+
+	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], ':');
+	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) {
+			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;
+		}
+	}
+
+	trace_probe_log_set_index(1);
+
+	/* 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;
+	}
+
+	trace_probe_log_set_index(0);
+	if (event) {
+		ret = traceprobe_parse_event_name(&event, &group, gbuf,
+						  event - argv[0]);
+		if (ret)
+			goto parse_error;
+	}
+
+	if (!event) {
+		/* Make a new event name */
+		if (is_tracepoint)
+			snprintf(buf, MAX_EVENT_NAME_LEN, "%s%s",
+				 isdigit(*symbol) ? "_" : "", symbol);
+		else
+			snprintf(buf, MAX_EVENT_NAME_LEN, "%s__%s", symbol,
+				 is_return ? "exit" : "entry");
+		sanitize_event_name(buf);
+		event = buf;
+	}
+
+	if (is_return)
+		ctx.flags |= TPARG_FL_RETURN;
+	else
+		ctx.flags |= TPARG_FL_FENTRY;
+
+	if (is_tracepoint) {
+		ctx.flags |= TPARG_FL_TPOINT;
+		tpoint = find_tracepoint(symbol);
+		if (!tpoint) {
+			trace_probe_log_set_index(1);
+			trace_probe_log_err(0, NO_TRACEPOINT);
+			goto parse_error;
+		}
+		ctx.funcname = kallsyms_lookup(
+				(unsigned long)tpoint->probestub,
+				NULL, NULL, NULL, sbuf);
+	} else
+		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;
+	}
+	if (new_argv) {
+		argc = new_argc;
+		argv = new_argv;
+	}
+
+	/* setup a probe */
+	tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive,
+				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 */
+	}
+
+	if (is_tracepoint)
+		tf->mod = __module_text_address(
+				(unsigned long)tf->tpoint->probestub);
+
+	/* parse arguments */
+	for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+		trace_probe_log_set_index(i + 2);
+		ctx.offset = 0;
+		ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx);
+		if (ret)
+			goto error;	/* This can be -ENOMEM */
+	}
+
+	ret = traceprobe_set_print_fmt(&tf->tp,
+			is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL);
+	if (ret < 0)
+		goto error;
+
+	ret = register_trace_fprobe(tf);
+	if (ret) {
+		trace_probe_log_set_index(1);
+		if (ret == -EILSEQ)
+			trace_probe_log_err(0, BAD_INSN_BNDRY);
+		else if (ret == -ENOENT)
+			trace_probe_log_err(0, BAD_PROBE_ADDR);
+		else if (ret != -ENOMEM && ret != -EEXIST)
+			trace_probe_log_err(0, FAIL_REG_PROBE);
+		goto error;
+	}
+
+out:
+	traceprobe_finish_parse(&ctx);
+	trace_probe_log_clear();
+	kfree(new_argv);
+	kfree(symbol);
+	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);
+}
+
+static int trace_fprobe_release(struct dyn_event *ev)
+{
+	struct trace_fprobe *tf = to_trace_fprobe(ev);
+	int ret = unregister_trace_fprobe(tf);
+
+	if (!ret)
+		free_trace_fprobe(tf);
+	return ret;
+}
+
+static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev)
+{
+	struct trace_fprobe *tf = to_trace_fprobe(ev);
+	int i;
+
+	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),
+				trace_probe_name(&tf->tp));
+
+	seq_printf(m, " %s%s", trace_fprobe_symbol(tf),
+			       trace_fprobe_is_return(tf) ? "%return" : "");
+
+	for (i = 0; i < tf->tp.nr_args; i++)
+		seq_printf(m, " %s=%s", tf->tp.args[i].name, tf->tp.args[i].comm);
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
+/*
+ * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
+ */
+static int fprobe_register(struct trace_event_call *event,
+			   enum trace_reg type, void *data)
+{
+	struct trace_event_file *file = data;
+
+	switch (type) {
+	case TRACE_REG_REGISTER:
+		return enable_trace_fprobe(event, file);
+	case TRACE_REG_UNREGISTER:
+		return disable_trace_fprobe(event, file);
+
+#ifdef CONFIG_PERF_EVENTS
+	case TRACE_REG_PERF_REGISTER:
+		return enable_trace_fprobe(event, NULL);
+	case TRACE_REG_PERF_UNREGISTER:
+		return disable_trace_fprobe(event, NULL);
+	case TRACE_REG_PERF_OPEN:
+	case TRACE_REG_PERF_CLOSE:
+	case TRACE_REG_PERF_ADD:
+	case TRACE_REG_PERF_DEL:
+		return 0;
+#endif
+	}
+	return 0;
+}
+
+/*
+ * Register dynevent at core_initcall. This allows kernel to setup fprobe
+ * events in postcore_initcall without tracefs.
+ */
+static __init int init_fprobe_trace_early(void)
+{
+	int ret;
+
+	ret = dyn_event_register(&trace_fprobe_ops);
+	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);