Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 2133 insertions, 0 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
new file mode 100644
index 000000000..e3993d196
--- /dev/null
+++ b/kernel/trace/trace_kprobe.c
@@ -0,0 +1,2133 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Kprobes-based tracing events
+ *
+ * Created by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ */
+#define pr_fmt(fmt)	"trace_kprobe: " fmt
+
+#include <linux/bpf-cgroup.h>
+#include <linux/security.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/rculist.h>
+#include <linux/error-injection.h>
+
+#include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
+
+#include "trace_dynevent.h"
+#include "trace_kprobe_selftest.h"
+#include "trace_probe.h"
+#include "trace_probe_tmpl.h"
+#include "trace_probe_kernel.h"
+
+#define KPROBE_EVENT_SYSTEM "kprobes"
+#define KRETPROBE_MAXACTIVE_MAX 4096
+
+/* Kprobe early definition from command line */
+static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
+
+static int __init set_kprobe_boot_events(char *str)
+{
+	strlcpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
+	disable_tracing_selftest("running kprobe events");
+
+	return 1;
+}
+__setup("kprobe_event=", set_kprobe_boot_events);
+
+static int trace_kprobe_create(const char *raw_command);
+static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
+static int trace_kprobe_release(struct dyn_event *ev);
+static bool trace_kprobe_is_busy(struct dyn_event *ev);
+static bool trace_kprobe_match(const char *system, const char *event,
+			int argc, const char **argv, struct dyn_event *ev);
+
+static struct dyn_event_operations trace_kprobe_ops = {
+	.create = trace_kprobe_create,
+	.show = trace_kprobe_show,
+	.is_busy = trace_kprobe_is_busy,
+	.free = trace_kprobe_release,
+	.match = trace_kprobe_match,
+};
+
+/*
+ * Kprobe event core functions
+ */
+struct trace_kprobe {
+	struct dyn_event	devent;
+	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
+	unsigned long __percpu *nhit;
+	const char		*symbol;	/* symbol name */
+	struct trace_probe	tp;
+};
+
+static bool is_trace_kprobe(struct dyn_event *ev)
+{
+	return ev->ops == &trace_kprobe_ops;
+}
+
+static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
+{
+	return container_of(ev, struct trace_kprobe, devent);
+}
+
+/**
+ * for_each_trace_kprobe - iterate over the trace_kprobe list
+ * @pos:	the struct trace_kprobe * for each entry
+ * @dpos:	the struct dyn_event * to use as a loop cursor
+ */
+#define for_each_trace_kprobe(pos, dpos)	\
+	for_each_dyn_event(dpos)		\
+		if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))
+
+static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
+{
+	return tk->rp.handler != NULL;
+}
+
+static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
+{
+	return tk->symbol ? tk->symbol : "unknown";
+}
+
+static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
+{
+	return tk->rp.kp.offset;
+}
+
+static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
+{
+	return kprobe_gone(&tk->rp.kp);
+}
+
+static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
+						 struct module *mod)
+{
+	int len = strlen(module_name(mod));
+	const char *name = trace_kprobe_symbol(tk);
+
+	return strncmp(module_name(mod), name, len) == 0 && name[len] == ':';
+}
+
+static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
+{
+	char *p;
+	bool ret;
+
+	if (!tk->symbol)
+		return false;
+	p = strchr(tk->symbol, ':');
+	if (!p)
+		return true;
+	*p = '\0';
+	rcu_read_lock_sched();
+	ret = !!find_module(tk->symbol);
+	rcu_read_unlock_sched();
+	*p = ':';
+
+	return ret;
+}
+
+static bool trace_kprobe_is_busy(struct dyn_event *ev)
+{
+	struct trace_kprobe *tk = to_trace_kprobe(ev);
+
+	return trace_probe_is_enabled(&tk->tp);
+}
+
+static bool trace_kprobe_match_command_head(struct trace_kprobe *tk,
+					    int argc, const char **argv)
+{
+	char buf[MAX_ARGSTR_LEN + 1];
+
+	if (!argc)
+		return true;
+
+	if (!tk->symbol)
+		snprintf(buf, sizeof(buf), "0x%p", tk->rp.kp.addr);
+	else if (tk->rp.kp.offset)
+		snprintf(buf, sizeof(buf), "%s+%u",
+			 trace_kprobe_symbol(tk), tk->rp.kp.offset);
+	else
+		snprintf(buf, sizeof(buf), "%s", trace_kprobe_symbol(tk));
+	if (strcmp(buf, argv[0]))
+		return false;
+	argc--; argv++;
+
+	return trace_probe_match_command_args(&tk->tp, argc, argv);
+}
+
+static bool trace_kprobe_match(const char *system, const char *event,
+			int argc, const char **argv, struct dyn_event *ev)
+{
+	struct trace_kprobe *tk = to_trace_kprobe(ev);
+
+	return (event[0] == '\0' ||
+		strcmp(trace_probe_name(&tk->tp), event) == 0) &&
+	    (!system || strcmp(trace_probe_group_name(&tk->tp), system) == 0) &&
+	    trace_kprobe_match_command_head(tk, argc, argv);
+}
+
+static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
+{
+	unsigned long nhit = 0;
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		nhit += *per_cpu_ptr(tk->nhit, cpu);
+
+	return nhit;
+}
+
+static nokprobe_inline bool trace_kprobe_is_registered(struct trace_kprobe *tk)
+{
+	return !(list_empty(&tk->rp.kp.list) &&
+		 hlist_unhashed(&tk->rp.kp.hlist));
+}
+
+/* Return 0 if it fails to find the symbol address */
+static nokprobe_inline
+unsigned long trace_kprobe_address(struct trace_kprobe *tk)
+{
+	unsigned long addr;
+
+	if (tk->symbol) {
+		addr = (unsigned long)
+			kallsyms_lookup_name(trace_kprobe_symbol(tk));
+		if (addr)
+			addr += tk->rp.kp.offset;
+	} else {
+		addr = (unsigned long)tk->rp.kp.addr;
+	}
+	return addr;
+}
+
+static nokprobe_inline struct trace_kprobe *
+trace_kprobe_primary_from_call(struct trace_event_call *call)
+{
+	struct trace_probe *tp;
+
+	tp = trace_probe_primary_from_call(call);
+	if (WARN_ON_ONCE(!tp))
+		return NULL;
+
+	return container_of(tp, struct trace_kprobe, tp);
+}
+
+bool trace_kprobe_on_func_entry(struct trace_event_call *call)
+{
+	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
+
+	return tk ? (kprobe_on_func_entry(tk->rp.kp.addr,
+			tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
+			tk->rp.kp.addr ? 0 : tk->rp.kp.offset) == 0) : false;
+}
+
+bool trace_kprobe_error_injectable(struct trace_event_call *call)
+{
+	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
+
+	return tk ? within_error_injection_list(trace_kprobe_address(tk)) :
+	       false;
+}
+
+static int register_kprobe_event(struct trace_kprobe *tk);
+static int unregister_kprobe_event(struct trace_kprobe *tk);
+
+static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
+static int kretprobe_dispatcher(struct kretprobe_instance *ri,
+				struct pt_regs *regs);
+
+static void free_trace_kprobe(struct trace_kprobe *tk)
+{
+	if (tk) {
+		trace_probe_cleanup(&tk->tp);
+		kfree(tk->symbol);
+		free_percpu(tk->nhit);
+		kfree(tk);
+	}
+}
+
+/*
+ * Allocate new trace_probe and initialize it (including kprobes).
+ */
+static struct trace_kprobe *alloc_trace_kprobe(const char *group,
+					     const char *event,
+					     void *addr,
+					     const char *symbol,
+					     unsigned long offs,
+					     int maxactive,
+					     int nargs, bool is_return)
+{
+	struct trace_kprobe *tk;
+	int ret = -ENOMEM;
+
+	tk = kzalloc(struct_size(tk, tp.args, nargs), GFP_KERNEL);
+	if (!tk)
+		return ERR_PTR(ret);
+
+	tk->nhit = alloc_percpu(unsigned long);
+	if (!tk->nhit)
+		goto error;
+
+	if (symbol) {
+		tk->symbol = kstrdup(symbol, GFP_KERNEL);
+		if (!tk->symbol)
+			goto error;
+		tk->rp.kp.symbol_name = tk->symbol;
+		tk->rp.kp.offset = offs;
+	} else
+		tk->rp.kp.addr = addr;
+
+	if (is_return)
+		tk->rp.handler = kretprobe_dispatcher;
+	else
+		tk->rp.kp.pre_handler = kprobe_dispatcher;
+
+	tk->rp.maxactive = maxactive;
+	INIT_HLIST_NODE(&tk->rp.kp.hlist);
+	INIT_LIST_HEAD(&tk->rp.kp.list);
+
+	ret = trace_probe_init(&tk->tp, event, group, false);
+	if (ret < 0)
+		goto error;
+
+	dyn_event_init(&tk->devent, &trace_kprobe_ops);
+	return tk;
+error:
+	free_trace_kprobe(tk);
+	return ERR_PTR(ret);
+}
+
+static struct trace_kprobe *find_trace_kprobe(const char *event,
+					      const char *group)
+{
+	struct dyn_event *pos;
+	struct trace_kprobe *tk;
+
+	for_each_trace_kprobe(tk, pos)
+		if (strcmp(trace_probe_name(&tk->tp), event) == 0 &&
+		    strcmp(trace_probe_group_name(&tk->tp), group) == 0)
+			return tk;
+	return NULL;
+}
+
+static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
+{
+	int ret = 0;
+
+	if (trace_kprobe_is_registered(tk) && !trace_kprobe_has_gone(tk)) {
+		if (trace_kprobe_is_return(tk))
+			ret = enable_kretprobe(&tk->rp);
+		else
+			ret = enable_kprobe(&tk->rp.kp);
+	}
+
+	return ret;
+}
+
+static void __disable_trace_kprobe(struct trace_probe *tp)
+{
+	struct trace_kprobe *tk;
+
+	list_for_each_entry(tk, trace_probe_probe_list(tp), tp.list) {
+		if (!trace_kprobe_is_registered(tk))
+			continue;
+		if (trace_kprobe_is_return(tk))
+			disable_kretprobe(&tk->rp);
+		else
+			disable_kprobe(&tk->rp.kp);
+	}
+}
+
+/*
+ * Enable trace_probe
+ * if the file is NULL, enable "perf" handler, or enable "trace" handler.
+ */
+static int enable_trace_kprobe(struct trace_event_call *call,
+				struct trace_event_file *file)
+{
+	struct trace_probe *tp;
+	struct trace_kprobe *tk;
+	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)
+		return 0;
+
+	list_for_each_entry(tk, trace_probe_probe_list(tp), tp.list) {
+		if (trace_kprobe_has_gone(tk))
+			continue;
+		ret = __enable_trace_kprobe(tk);
+		if (ret)
+			break;
+		enabled = true;
+	}
+
+	if (ret) {
+		/* Failed to enable one of them. Roll back all */
+		if (enabled)
+			__disable_trace_kprobe(tp);
+		if (file)
+			trace_probe_remove_file(tp, file);
+		else
+			trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
+	}
+
+	return ret;
+}
+
+/*
+ * Disable trace_probe
+ * if the file is NULL, disable "perf" handler, or disable "trace" handler.
+ */
+static int disable_trace_kprobe(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_kprobe(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;
+}
+
+#if defined(CONFIG_DYNAMIC_FTRACE) && \
+	!defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
+static bool __within_notrace_func(unsigned long addr)
+{
+	unsigned long offset, size;
+
+	if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))
+		return false;
+
+	/* Get the entry address of the target function */
+	addr -= offset;
+
+	/*
+	 * Since ftrace_location_range() does inclusive range check, we need
+	 * to subtract 1 byte from the end address.
+	 */
+	return !ftrace_location_range(addr, addr + size - 1);
+}
+
+static bool within_notrace_func(struct trace_kprobe *tk)
+{
+	unsigned long addr = trace_kprobe_address(tk);
+	char symname[KSYM_NAME_LEN], *p;
+
+	if (!__within_notrace_func(addr))
+		return false;
+
+	/* Check if the address is on a suffixed-symbol */
+	if (!lookup_symbol_name(addr, symname)) {
+		p = strchr(symname, '.');
+		if (!p)
+			return true;
+		*p = '\0';
+		addr = (unsigned long)kprobe_lookup_name(symname, 0);
+		if (addr)
+			return __within_notrace_func(addr);
+	}
+
+	return true;
+}
+#else
+#define within_notrace_func(tk)	(false)
+#endif
+
+/* Internal register function - just handle k*probes and flags */
+static int __register_trace_kprobe(struct trace_kprobe *tk)
+{
+	int i, ret;
+
+	ret = security_locked_down(LOCKDOWN_KPROBES);
+	if (ret)
+		return ret;
+
+	if (trace_kprobe_is_registered(tk))
+		return -EINVAL;
+
+	if (within_notrace_func(tk)) {
+		pr_warn("Could not probe notrace function %s\n",
+			trace_kprobe_symbol(tk));
+		return -EINVAL;
+	}
+
+	for (i = 0; i < tk->tp.nr_args; i++) {
+		ret = traceprobe_update_arg(&tk->tp.args[i]);
+		if (ret)
+			return ret;
+	}
+
+	/* Set/clear disabled flag according to tp->flag */
+	if (trace_probe_is_enabled(&tk->tp))
+		tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
+	else
+		tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
+
+	if (trace_kprobe_is_return(tk))
+		ret = register_kretprobe(&tk->rp);
+	else
+		ret = register_kprobe(&tk->rp.kp);
+
+	return ret;
+}
+
+/* Internal unregister function - just handle k*probes and flags */
+static void __unregister_trace_kprobe(struct trace_kprobe *tk)
+{
+	if (trace_kprobe_is_registered(tk)) {
+		if (trace_kprobe_is_return(tk))
+			unregister_kretprobe(&tk->rp);
+		else
+			unregister_kprobe(&tk->rp.kp);
+		/* Cleanup kprobe for reuse and mark it unregistered */
+		INIT_HLIST_NODE(&tk->rp.kp.hlist);
+		INIT_LIST_HEAD(&tk->rp.kp.list);
+		if (tk->rp.kp.symbol_name)
+			tk->rp.kp.addr = NULL;
+	}
+}
+
+/* Unregister a trace_probe and probe_event */
+static int unregister_trace_kprobe(struct trace_kprobe *tk)
+{
+	/* If other probes are on the event, just unregister kprobe */
+	if (trace_probe_has_sibling(&tk->tp))
+		goto unreg;
+
+	/* Enabled event can not be unregistered */
+	if (trace_probe_is_enabled(&tk->tp))
+		return -EBUSY;
+
+	/* If there's a reference to the dynamic event */
+	if (trace_event_dyn_busy(trace_probe_event_call(&tk->tp)))
+		return -EBUSY;
+
+	/* Will fail if probe is being used by ftrace or perf */
+	if (unregister_kprobe_event(tk))
+		return -EBUSY;
+
+unreg:
+	__unregister_trace_kprobe(tk);
+	dyn_event_remove(&tk->devent);
+	trace_probe_unlink(&tk->tp);
+
+	return 0;
+}
+
+static bool trace_kprobe_has_same_kprobe(struct trace_kprobe *orig,
+					 struct trace_kprobe *comp)
+{
+	struct trace_probe_event *tpe = orig->tp.event;
+	int i;
+
+	list_for_each_entry(orig, &tpe->probes, tp.list) {
+		if (strcmp(trace_kprobe_symbol(orig),
+			   trace_kprobe_symbol(comp)) ||
+		    trace_kprobe_offset(orig) != trace_kprobe_offset(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_kprobe(struct trace_kprobe *tk, struct trace_kprobe *to)
+{
+	int ret;
+
+	ret = trace_probe_compare_arg_type(&tk->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_kprobe_has_same_kprobe(to, tk)) {
+		trace_probe_log_set_index(0);
+		trace_probe_log_err(0, SAME_PROBE);
+		return -EEXIST;
+	}
+
+	/* Append to existing event */
+	ret = trace_probe_append(&tk->tp, &to->tp);
+	if (ret)
+		return ret;
+
+	/* Register k*probe */
+	ret = __register_trace_kprobe(tk);
+	if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
+		pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
+		ret = 0;
+	}
+
+	if (ret)
+		trace_probe_unlink(&tk->tp);
+	else
+		dyn_event_add(&tk->devent, trace_probe_event_call(&tk->tp));
+
+	return ret;
+}
+
+/* Register a trace_probe and probe_event */
+static int register_trace_kprobe(struct trace_kprobe *tk)
+{
+	struct trace_kprobe *old_tk;
+	int ret;
+
+	mutex_lock(&event_mutex);
+
+	old_tk = find_trace_kprobe(trace_probe_name(&tk->tp),
+				   trace_probe_group_name(&tk->tp));
+	if (old_tk) {
+		if (trace_kprobe_is_return(tk) != trace_kprobe_is_return(old_tk)) {
+			trace_probe_log_set_index(0);
+			trace_probe_log_err(0, DIFF_PROBE_TYPE);
+			ret = -EEXIST;
+		} else {
+			ret = append_trace_kprobe(tk, old_tk);
+		}
+		goto end;
+	}
+
+	/* Register new event */
+	ret = register_kprobe_event(tk);
+	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 k*probe */
+	ret = __register_trace_kprobe(tk);
+	if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
+		pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
+		ret = 0;
+	}
+
+	if (ret < 0)
+		unregister_kprobe_event(tk);
+	else
+		dyn_event_add(&tk->devent, trace_probe_event_call(&tk->tp));
+
+end:
+	mutex_unlock(&event_mutex);
+	return ret;
+}
+
+/* Module notifier call back, checking event on the module */
+static int trace_kprobe_module_callback(struct notifier_block *nb,
+				       unsigned long val, void *data)
+{
+	struct module *mod = data;
+	struct dyn_event *pos;
+	struct trace_kprobe *tk;
+	int ret;
+
+	if (val != MODULE_STATE_COMING)
+		return NOTIFY_DONE;
+
+	/* Update probes on coming module */
+	mutex_lock(&event_mutex);
+	for_each_trace_kprobe(tk, pos) {
+		if (trace_kprobe_within_module(tk, mod)) {
+			/* Don't need to check busy - this should have gone. */
+			__unregister_trace_kprobe(tk);
+			ret = __register_trace_kprobe(tk);
+			if (ret)
+				pr_warn("Failed to re-register probe %s on %s: %d\n",
+					trace_probe_name(&tk->tp),
+					module_name(mod), ret);
+		}
+	}
+	mutex_unlock(&event_mutex);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block trace_kprobe_module_nb = {
+	.notifier_call = trace_kprobe_module_callback,
+	.priority = 1	/* Invoked after kprobe module callback */
+};
+
+static int count_symbols(void *data, unsigned long unused)
+{
+	unsigned int *count = data;
+
+	(*count)++;
+
+	return 0;
+}
+
+struct sym_count_ctx {
+	unsigned int count;
+	const char *name;
+};
+
+static int count_mod_symbols(void *data, const char *name,
+			     struct module *module, unsigned long unused)
+{
+	struct sym_count_ctx *ctx = data;
+
+	if (strcmp(name, ctx->name) == 0)
+		ctx->count++;
+
+	return 0;
+}
+
+static unsigned int number_of_same_symbols(char *func_name)
+{
+	struct sym_count_ctx ctx = { .count = 0, .name = func_name };
+
+	kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
+
+	module_kallsyms_on_each_symbol(count_mod_symbols, &ctx);
+
+	return ctx.count;
+}
+
+static int __trace_kprobe_create(int argc, const char *argv[])
+{
+	/*
+	 * Argument syntax:
+	 *  - Add kprobe:
+	 *      p[:[GRP/][EVENT]] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
+	 *  - Add kretprobe:
+	 *      r[MAXACTIVE][:[GRP/][EVENT]] [MOD:]KSYM[+0] [FETCHARGS]
+	 *    Or
+	 *      p[:[GRP/][EVENT]] [MOD:]KSYM[+0]%return [FETCHARGS]
+	 *
+	 * Fetch args:
+	 *  $retval	: fetch return value
+	 *  $stack	: fetch stack address
+	 *  $stackN	: fetch Nth of stack (N:0-)
+	 *  $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)
+	 *  %REG	: fetch register REG
+	 * 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_kprobe *tk = NULL;
+	int i, len, ret = 0;
+	bool is_return = false;
+	char *symbol = NULL, *tmp = NULL;
+	const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
+	enum probe_print_type ptype;
+	int maxactive = 0;
+	long offset = 0;
+	void *addr = NULL;
+	char buf[MAX_EVENT_NAME_LEN];
+	char gbuf[MAX_EVENT_NAME_LEN];
+	unsigned int flags = TPARG_FL_KERNEL;
+
+	switch (argv[0][0]) {
+	case 'r':
+		is_return = true;
+		break;
+	case 'p':
+		break;
+	default:
+		return -ECANCELED;
+	}
+	if (argc < 2)
+		return -ECANCELED;
+
+	trace_probe_log_init("trace_kprobe", argc, argv);
+
+	event = strchr(&argv[0][1], ':');
+	if (event)
+		event++;
+
+	if (isdigit(argv[0][1])) {
+		if (!is_return) {
+			trace_probe_log_err(1, MAXACT_NO_KPROBE);
+			goto parse_error;
+		}
+		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;
+		}
+		/* kretprobes instances are iterated over via a list. The
+		 * maximum should stay reasonable.
+		 */
+		if (maxactive > KRETPROBE_MAXACTIVE_MAX) {
+			trace_probe_log_err(1, MAXACT_TOO_BIG);
+			goto parse_error;
+		}
+	}
+
+	/* try to parse an address. if that fails, try to read the
+	 * input as a symbol. */
+	if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
+		trace_probe_log_set_index(1);
+		/* Check whether uprobe event specified */
+		if (strchr(argv[1], '/') && strchr(argv[1], ':')) {
+			ret = -ECANCELED;
+			goto error;
+		}
+		/* a symbol specified */
+		symbol = kstrdup(argv[1], GFP_KERNEL);
+		if (!symbol)
+			return -ENOMEM;
+
+		tmp = strchr(symbol, '%');
+		if (tmp) {
+			if (!strcmp(tmp, "%return")) {
+				*tmp = '\0';
+				is_return = true;
+			} else {
+				trace_probe_log_err(tmp - symbol, BAD_ADDR_SUFFIX);
+				goto parse_error;
+			}
+		}
+
+		/* TODO: support .init module functions */
+		ret = traceprobe_split_symbol_offset(symbol, &offset);
+		if (ret || offset < 0 || offset > UINT_MAX) {
+			trace_probe_log_err(0, BAD_PROBE_ADDR);
+			goto parse_error;
+		}
+		if (is_return)
+			flags |= TPARG_FL_RETURN;
+		ret = kprobe_on_func_entry(NULL, symbol, offset);
+		if (ret == 0)
+			flags |= TPARG_FL_FENTRY;
+		/* Defer the ENOENT case until register kprobe */
+		if (ret == -EINVAL && is_return) {
+			trace_probe_log_err(0, BAD_RETPROBE);
+			goto parse_error;
+		}
+	}
+
+	if (symbol && !strchr(symbol, ':')) {
+		unsigned int count;
+
+		count = number_of_same_symbols(symbol);
+		if (count > 1) {
+			/*
+			 * Users should use ADDR to remove the ambiguity of
+			 * using KSYM only.
+			 */
+			trace_probe_log_err(0, NON_UNIQ_SYMBOL);
+			ret = -EADDRNOTAVAIL;
+
+			goto error;
+		} else if (count == 0) {
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			trace_probe_log_err(0, BAD_PROBE_ADDR);
+			ret = -ENOENT;
+
+			goto 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 (symbol)
+			snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
+				 is_return ? 'r' : 'p', symbol, offset);
+		else
+			snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
+				 is_return ? 'r' : 'p', addr);
+		sanitize_event_name(buf);
+		event = buf;
+	}
+
+	/* setup a probe */
+	tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
+			       argc - 2, is_return);
+	if (IS_ERR(tk)) {
+		ret = PTR_ERR(tk);
+		/* This must return -ENOMEM, else there is a bug */
+		WARN_ON_ONCE(ret != -ENOMEM);
+		goto out;	/* We know tk is not allocated */
+	}
+	argc -= 2; argv += 2;
+
+	/* parse arguments */
+	for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+		trace_probe_log_set_index(i + 2);
+		ret = traceprobe_parse_probe_arg(&tk->tp, i, argv[i], flags);
+		if (ret)
+			goto error;	/* This can be -ENOMEM */
+	}
+
+	ptype = is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
+	ret = traceprobe_set_print_fmt(&tk->tp, ptype);
+	if (ret < 0)
+		goto error;
+
+	ret = register_trace_kprobe(tk);
+	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:
+	trace_probe_log_clear();
+	kfree(symbol);
+	return ret;
+
+parse_error:
+	ret = -EINVAL;
+error:
+	free_trace_kprobe(tk);
+	goto out;
+}
+
+static int trace_kprobe_create(const char *raw_command)
+{
+	return trace_probe_create(raw_command, __trace_kprobe_create);
+}
+
+static int create_or_delete_trace_kprobe(const char *raw_command)
+{
+	int ret;
+
+	if (raw_command[0] == '-')
+		return dyn_event_release(raw_command, &trace_kprobe_ops);
+
+	ret = trace_kprobe_create(raw_command);
+	return ret == -ECANCELED ? -EINVAL : ret;
+}
+
+static int trace_kprobe_run_command(struct dynevent_cmd *cmd)
+{
+	return create_or_delete_trace_kprobe(cmd->seq.buffer);
+}
+
+/**
+ * kprobe_event_cmd_init - Initialize a kprobe event command object
+ * @cmd: A pointer to the dynevent_cmd struct representing the new event
+ * @buf: A pointer to the buffer used to build the command
+ * @maxlen: The length of the buffer passed in @buf
+ *
+ * Initialize a synthetic event command object.  Use this before
+ * calling any of the other kprobe_event functions.
+ */
+void kprobe_event_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen)
+{
+	dynevent_cmd_init(cmd, buf, maxlen, DYNEVENT_TYPE_KPROBE,
+			  trace_kprobe_run_command);
+}
+EXPORT_SYMBOL_GPL(kprobe_event_cmd_init);
+
+/**
+ * __kprobe_event_gen_cmd_start - Generate a kprobe event command from arg list
+ * @cmd: A pointer to the dynevent_cmd struct representing the new event
+ * @kretprobe: Is this a return probe?
+ * @name: The name of the kprobe event
+ * @loc: The location of the kprobe event
+ * @...: Variable number of arg (pairs), one pair for each field
+ *
+ * NOTE: Users normally won't want to call this function directly, but
+ * rather use the kprobe_event_gen_cmd_start() wrapper, which automatically
+ * adds a NULL to the end of the arg list.  If this function is used
+ * directly, make sure the last arg in the variable arg list is NULL.
+ *
+ * Generate a kprobe event command to be executed by
+ * kprobe_event_gen_cmd_end().  This function can be used to generate the
+ * complete command or only the first part of it; in the latter case,
+ * kprobe_event_add_fields() can be used to add more fields following this.
+ *
+ * Unlikely the synth_event_gen_cmd_start(), @loc must be specified. This
+ * returns -EINVAL if @loc == NULL.
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
+				 const char *name, const char *loc, ...)
+{
+	char buf[MAX_EVENT_NAME_LEN];
+	struct dynevent_arg arg;
+	va_list args;
+	int ret;
+
+	if (cmd->type != DYNEVENT_TYPE_KPROBE)
+		return -EINVAL;
+
+	if (!loc)
+		return -EINVAL;
+
+	if (kretprobe)
+		snprintf(buf, MAX_EVENT_NAME_LEN, "r:kprobes/%s", name);
+	else
+		snprintf(buf, MAX_EVENT_NAME_LEN, "p:kprobes/%s", name);
+
+	ret = dynevent_str_add(cmd, buf);
+	if (ret)
+		return ret;
+
+	dynevent_arg_init(&arg, 0);
+	arg.str = loc;
+	ret = dynevent_arg_add(cmd, &arg, NULL);
+	if (ret)
+		return ret;
+
+	va_start(args, loc);
+	for (;;) {
+		const char *field;
+
+		field = va_arg(args, const char *);
+		if (!field)
+			break;
+
+		if (++cmd->n_fields > MAX_TRACE_ARGS) {
+			ret = -EINVAL;
+			break;
+		}
+
+		arg.str = field;
+		ret = dynevent_arg_add(cmd, &arg, NULL);
+		if (ret)
+			break;
+	}
+	va_end(args);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__kprobe_event_gen_cmd_start);
+
+/**
+ * __kprobe_event_add_fields - Add probe fields to a kprobe command from arg list
+ * @cmd: A pointer to the dynevent_cmd struct representing the new event
+ * @...: Variable number of arg (pairs), one pair for each field
+ *
+ * NOTE: Users normally won't want to call this function directly, but
+ * rather use the kprobe_event_add_fields() wrapper, which
+ * automatically adds a NULL to the end of the arg list.  If this
+ * function is used directly, make sure the last arg in the variable
+ * arg list is NULL.
+ *
+ * Add probe fields to an existing kprobe command using a variable
+ * list of args.  Fields are added in the same order they're listed.
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...)
+{
+	struct dynevent_arg arg;
+	va_list args;
+	int ret = 0;
+
+	if (cmd->type != DYNEVENT_TYPE_KPROBE)
+		return -EINVAL;
+
+	dynevent_arg_init(&arg, 0);
+
+	va_start(args, cmd);
+	for (;;) {
+		const char *field;
+
+		field = va_arg(args, const char *);
+		if (!field)
+			break;
+
+		if (++cmd->n_fields > MAX_TRACE_ARGS) {
+			ret = -EINVAL;
+			break;
+		}
+
+		arg.str = field;
+		ret = dynevent_arg_add(cmd, &arg, NULL);
+		if (ret)
+			break;
+	}
+	va_end(args);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__kprobe_event_add_fields);
+
+/**
+ * kprobe_event_delete - Delete a kprobe event
+ * @name: The name of the kprobe event to delete
+ *
+ * Delete a kprobe event with the give @name from kernel code rather
+ * than directly from the command line.
+ *
+ * Return: 0 if successful, error otherwise.
+ */
+int kprobe_event_delete(const char *name)
+{
+	char buf[MAX_EVENT_NAME_LEN];
+
+	snprintf(buf, MAX_EVENT_NAME_LEN, "-:%s", name);
+
+	return create_or_delete_trace_kprobe(buf);
+}
+EXPORT_SYMBOL_GPL(kprobe_event_delete);
+
+static int trace_kprobe_release(struct dyn_event *ev)
+{
+	struct trace_kprobe *tk = to_trace_kprobe(ev);
+	int ret = unregister_trace_kprobe(tk);
+
+	if (!ret)
+		free_trace_kprobe(tk);
+	return ret;
+}
+
+static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)
+{
+	struct trace_kprobe *tk = to_trace_kprobe(ev);
+	int i;
+
+	seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
+	if (trace_kprobe_is_return(tk) && tk->rp.maxactive)
+		seq_printf(m, "%d", tk->rp.maxactive);
+	seq_printf(m, ":%s/%s", trace_probe_group_name(&tk->tp),
+				trace_probe_name(&tk->tp));
+
+	if (!tk->symbol)
+		seq_printf(m, " 0x%p", tk->rp.kp.addr);
+	else if (tk->rp.kp.offset)
+		seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
+			   tk->rp.kp.offset);
+	else
+		seq_printf(m, " %s", trace_kprobe_symbol(tk));
+
+	for (i = 0; i < tk->tp.nr_args; i++)
+		seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
+static int probes_seq_show(struct seq_file *m, void *v)
+{
+	struct dyn_event *ev = v;
+
+	if (!is_trace_kprobe(ev))
+		return 0;
+
+	return trace_kprobe_show(m, ev);
+}
+
+static const struct seq_operations probes_seq_op = {
+	.start  = dyn_event_seq_start,
+	.next   = dyn_event_seq_next,
+	.stop   = dyn_event_seq_stop,
+	.show   = probes_seq_show
+};
+
+static int probes_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	if (ret)
+		return ret;
+
+	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+		ret = dyn_events_release_all(&trace_kprobe_ops);
+		if (ret < 0)
+			return ret;
+	}
+
+	return seq_open(file, &probes_seq_op);
+}
+
+static ssize_t probes_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	return trace_parse_run_command(file, buffer, count, ppos,
+				       create_or_delete_trace_kprobe);
+}
+
+static const struct file_operations kprobe_events_ops = {
+	.owner          = THIS_MODULE,
+	.open           = probes_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+	.write		= probes_write,
+};
+
+/* Probes profiling interfaces */
+static int probes_profile_seq_show(struct seq_file *m, void *v)
+{
+	struct dyn_event *ev = v;
+	struct trace_kprobe *tk;
+	unsigned long nmissed;
+
+	if (!is_trace_kprobe(ev))
+		return 0;
+
+	tk = to_trace_kprobe(ev);
+	nmissed = trace_kprobe_is_return(tk) ?
+		tk->rp.kp.nmissed + tk->rp.nmissed : tk->rp.kp.nmissed;
+	seq_printf(m, "  %-44s %15lu %15lu\n",
+		   trace_probe_name(&tk->tp),
+		   trace_kprobe_nhit(tk),
+		   nmissed);
+
+	return 0;
+}
+
+static const struct seq_operations profile_seq_op = {
+	.start  = dyn_event_seq_start,
+	.next   = dyn_event_seq_next,
+	.stop   = dyn_event_seq_stop,
+	.show   = probes_profile_seq_show
+};
+
+static int profile_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	if (ret)
+		return ret;
+
+	return seq_open(file, &profile_seq_op);
+}
+
+static const struct file_operations kprobe_profile_ops = {
+	.owner          = THIS_MODULE,
+	.open           = profile_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
+/* Kprobe specific fetch functions */
+
+/* Return the length of string -- including null terminal byte */
+static nokprobe_inline int
+fetch_store_strlen_user(unsigned long addr)
+{
+	return kern_fetch_store_strlen_user(addr);
+}
+
+/* Return the length of string -- including null terminal byte */
+static nokprobe_inline int
+fetch_store_strlen(unsigned long addr)
+{
+	return kern_fetch_store_strlen(addr);
+}
+
+/*
+ * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
+ * with max length and relative data location.
+ */
+static nokprobe_inline int
+fetch_store_string_user(unsigned long addr, void *dest, void *base)
+{
+	return kern_fetch_store_string_user(addr, dest, base);
+}
+
+/*
+ * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
+ * length and relative data location.
+ */
+static nokprobe_inline int
+fetch_store_string(unsigned long addr, void *dest, void *base)
+{
+	return kern_fetch_store_string(addr, dest, base);
+}
+
+static nokprobe_inline int
+probe_mem_read_user(void *dest, void *src, size_t size)
+{
+	const void __user *uaddr =  (__force const void __user *)src;
+
+	return copy_from_user_nofault(dest, uaddr, size);
+}
+
+static nokprobe_inline int
+probe_mem_read(void *dest, void *src, size_t size)
+{
+#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+	if ((unsigned long)src < TASK_SIZE)
+		return probe_mem_read_user(dest, src, size);
+#endif
+	return copy_from_kernel_nofault(dest, src, size);
+}
+
+/* Note that we don't verify it, since the code does not come from user space */
+static int
+process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
+		   void *base)
+{
+	struct pt_regs *regs = rec;
+	unsigned long val;
+
+retry:
+	/* 1st stage: get value from context */
+	switch (code->op) {
+	case FETCH_OP_REG:
+		val = regs_get_register(regs, code->param);
+		break;
+	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;
+	case FETCH_OP_IMM:
+		val = code->immediate;
+		break;
+	case FETCH_OP_COMM:
+		val = (unsigned long)current->comm;
+		break;
+	case FETCH_OP_DATA:
+		val = (unsigned long)code->data;
+		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:
+		return -EILSEQ;
+	}
+	code++;
+
+	return process_fetch_insn_bottom(code, val, dest, base);
+}
+NOKPROBE_SYMBOL(process_fetch_insn)
+
+/* Kprobe handler */
+static nokprobe_inline void
+__kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
+		    struct trace_event_file *trace_file)
+{
+	struct kprobe_trace_entry_head *entry;
+	struct trace_event_call *call = trace_probe_event_call(&tk->tp);
+	struct trace_event_buffer fbuffer;
+	int dsize;
+
+	WARN_ON(call != trace_file->event_call);
+
+	if (trace_trigger_soft_disabled(trace_file))
+		return;
+
+	dsize = __get_data_size(&tk->tp, regs);
+
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+					   sizeof(*entry) + tk->tp.size + dsize);
+	if (!entry)
+		return;
+
+	fbuffer.regs = regs;
+	entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
+	entry->ip = (unsigned long)tk->rp.kp.addr;
+	store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
+
+	trace_event_buffer_commit(&fbuffer);
+}
+
+static void
+kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
+{
+	struct event_file_link *link;
+
+	trace_probe_for_each_link_rcu(link, &tk->tp)
+		__kprobe_trace_func(tk, regs, link->file);
+}
+NOKPROBE_SYMBOL(kprobe_trace_func);
+
+/* Kretprobe handler */
+static nokprobe_inline void
+__kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
+		       struct pt_regs *regs,
+		       struct trace_event_file *trace_file)
+{
+	struct kretprobe_trace_entry_head *entry;
+	struct trace_event_buffer fbuffer;
+	struct trace_event_call *call = trace_probe_event_call(&tk->tp);
+	int dsize;
+
+	WARN_ON(call != trace_file->event_call);
+
+	if (trace_trigger_soft_disabled(trace_file))
+		return;
+
+	dsize = __get_data_size(&tk->tp, regs);
+
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+					   sizeof(*entry) + tk->tp.size + dsize);
+	if (!entry)
+		return;
+
+	fbuffer.regs = regs;
+	entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
+	entry->func = (unsigned long)tk->rp.kp.addr;
+	entry->ret_ip = get_kretprobe_retaddr(ri);
+	store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
+
+	trace_event_buffer_commit(&fbuffer);
+}
+
+static void
+kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
+		     struct pt_regs *regs)
+{
+	struct event_file_link *link;
+
+	trace_probe_for_each_link_rcu(link, &tk->tp)
+		__kretprobe_trace_func(tk, ri, regs, link->file);
+}
+NOKPROBE_SYMBOL(kretprobe_trace_func);
+
+/* Event entry printers */
+static enum print_line_t
+print_kprobe_event(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
+{
+	struct kprobe_trace_entry_head *field;
+	struct trace_seq *s = &iter->seq;
+	struct trace_probe *tp;
+
+	field = (struct kprobe_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 (print_probe_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_kretprobe_event(struct trace_iterator *iter, int flags,
+		      struct trace_event *event)
+{
+	struct kretprobe_trace_entry_head *field;
+	struct trace_seq *s = &iter->seq;
+	struct trace_probe *tp;
+
+	field = (struct kretprobe_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 (print_probe_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 kprobe_event_define_fields(struct trace_event_call *event_call)
+{
+	int ret;
+	struct kprobe_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 kretprobe_event_define_fields(struct trace_event_call *event_call)
+{
+	int ret;
+	struct kretprobe_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);
+}
+
+#ifdef CONFIG_PERF_EVENTS
+
+/* Kprobe profile handler */
+static int
+kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
+{
+	struct trace_event_call *call = trace_probe_event_call(&tk->tp);
+	struct kprobe_trace_entry_head *entry;
+	struct hlist_head *head;
+	int size, __size, dsize;
+	int rctx;
+
+	if (bpf_prog_array_valid(call)) {
+		unsigned long orig_ip = instruction_pointer(regs);
+		int ret;
+
+		ret = trace_call_bpf(call, regs);
+
+		/*
+		 * We need to check and see if we modified the pc of the
+		 * pt_regs, and if so return 1 so that we don't do the
+		 * single stepping.
+		 */
+		if (orig_ip != instruction_pointer(regs))
+			return 1;
+		if (!ret)
+			return 0;
+	}
+
+	head = this_cpu_ptr(call->perf_events);
+	if (hlist_empty(head))
+		return 0;
+
+	dsize = __get_data_size(&tk->tp, regs);
+	__size = sizeof(*entry) + tk->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 = (unsigned long)tk->rp.kp.addr;
+	memset(&entry[1], 0, dsize);
+	store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
+	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
+			      head, NULL);
+	return 0;
+}
+NOKPROBE_SYMBOL(kprobe_perf_func);
+
+/* Kretprobe profile handler */
+static void
+kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
+		    struct pt_regs *regs)
+{
+	struct trace_event_call *call = trace_probe_event_call(&tk->tp);
+	struct kretprobe_trace_entry_head *entry;
+	struct hlist_head *head;
+	int size, __size, dsize;
+	int rctx;
+
+	if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
+		return;
+
+	head = this_cpu_ptr(call->perf_events);
+	if (hlist_empty(head))
+		return;
+
+	dsize = __get_data_size(&tk->tp, regs);
+	__size = sizeof(*entry) + tk->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 = (unsigned long)tk->rp.kp.addr;
+	entry->ret_ip = get_kretprobe_retaddr(ri);
+	store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
+	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
+			      head, NULL);
+}
+NOKPROBE_SYMBOL(kretprobe_perf_func);
+
+int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
+			const char **symbol, u64 *probe_offset,
+			u64 *probe_addr, bool perf_type_tracepoint)
+{
+	const char *pevent = trace_event_name(event->tp_event);
+	const char *group = event->tp_event->class->system;
+	struct trace_kprobe *tk;
+
+	if (perf_type_tracepoint)
+		tk = find_trace_kprobe(pevent, group);
+	else
+		tk = trace_kprobe_primary_from_call(event->tp_event);
+	if (!tk)
+		return -EINVAL;
+
+	*fd_type = trace_kprobe_is_return(tk) ? BPF_FD_TYPE_KRETPROBE
+					      : BPF_FD_TYPE_KPROBE;
+	if (tk->symbol) {
+		*symbol = tk->symbol;
+		*probe_offset = tk->rp.kp.offset;
+		*probe_addr = 0;
+	} else {
+		*symbol = NULL;
+		*probe_offset = 0;
+		*probe_addr = (unsigned long)tk->rp.kp.addr;
+	}
+	return 0;
+}
+#endif	/* CONFIG_PERF_EVENTS */
+
+/*
+ * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
+ *
+ * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
+ * lockless, but we can't race with this __init function.
+ */
+static int kprobe_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_kprobe(event, file);
+	case TRACE_REG_UNREGISTER:
+		return disable_trace_kprobe(event, file);
+
+#ifdef CONFIG_PERF_EVENTS
+	case TRACE_REG_PERF_REGISTER:
+		return enable_trace_kprobe(event, NULL);
+	case TRACE_REG_PERF_UNREGISTER:
+		return disable_trace_kprobe(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;
+}
+
+static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
+{
+	struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
+	int ret = 0;
+
+	raw_cpu_inc(*tk->nhit);
+
+	if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE))
+		kprobe_trace_func(tk, regs);
+#ifdef CONFIG_PERF_EVENTS
+	if (trace_probe_test_flag(&tk->tp, TP_FLAG_PROFILE))
+		ret = kprobe_perf_func(tk, regs);
+#endif
+	return ret;
+}
+NOKPROBE_SYMBOL(kprobe_dispatcher);
+
+static int
+kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	struct kretprobe *rp = get_kretprobe(ri);
+	struct trace_kprobe *tk;
+
+	/*
+	 * There is a small chance that get_kretprobe(ri) returns NULL when
+	 * the kretprobe is unregister on another CPU between kretprobe's
+	 * trampoline_handler and this function.
+	 */
+	if (unlikely(!rp))
+		return 0;
+
+	tk = container_of(rp, struct trace_kprobe, rp);
+	raw_cpu_inc(*tk->nhit);
+
+	if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE))
+		kretprobe_trace_func(tk, ri, regs);
+#ifdef CONFIG_PERF_EVENTS
+	if (trace_probe_test_flag(&tk->tp, TP_FLAG_PROFILE))
+		kretprobe_perf_func(tk, ri, regs);
+#endif
+	return 0;	/* We don't tweak kernel, so just return 0 */
+}
+NOKPROBE_SYMBOL(kretprobe_dispatcher);
+
+static struct trace_event_functions kretprobe_funcs = {
+	.trace		= print_kretprobe_event
+};
+
+static struct trace_event_functions kprobe_funcs = {
+	.trace		= print_kprobe_event
+};
+
+static struct trace_event_fields kretprobe_fields_array[] = {
+	{ .type = TRACE_FUNCTION_TYPE,
+	  .define_fields = kretprobe_event_define_fields },
+	{}
+};
+
+static struct trace_event_fields kprobe_fields_array[] = {
+	{ .type = TRACE_FUNCTION_TYPE,
+	  .define_fields = kprobe_event_define_fields },
+	{}
+};
+
+static inline void init_trace_event_call(struct trace_kprobe *tk)
+{
+	struct trace_event_call *call = trace_probe_event_call(&tk->tp);
+
+	if (trace_kprobe_is_return(tk)) {
+		call->event.funcs = &kretprobe_funcs;
+		call->class->fields_array = kretprobe_fields_array;
+	} else {
+		call->event.funcs = &kprobe_funcs;
+		call->class->fields_array = kprobe_fields_array;
+	}
+
+	call->flags = TRACE_EVENT_FL_KPROBE;
+	call->class->reg = kprobe_register;
+}
+
+static int register_kprobe_event(struct trace_kprobe *tk)
+{
+	init_trace_event_call(tk);
+
+	return trace_probe_register_event_call(&tk->tp);
+}
+
+static int unregister_kprobe_event(struct trace_kprobe *tk)
+{
+	return trace_probe_unregister_event_call(&tk->tp);
+}
+
+#ifdef CONFIG_PERF_EVENTS
+
+/* create a trace_kprobe, but don't add it to global lists */
+struct trace_event_call *
+create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
+			  bool is_return)
+{
+	enum probe_print_type ptype;
+	struct trace_kprobe *tk;
+	int ret;
+	char *event;
+
+	if (func) {
+		unsigned int count;
+
+		count = number_of_same_symbols(func);
+		if (count > 1)
+			/*
+			 * Users should use addr to remove the ambiguity of
+			 * using func only.
+			 */
+			return ERR_PTR(-EADDRNOTAVAIL);
+		else if (count == 0)
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			return ERR_PTR(-ENOENT);
+	}
+
+	/*
+	 * local trace_kprobes are not added to dyn_event, so they are never
+	 * searched in find_trace_kprobe(). Therefore, there is no concern of
+	 * duplicated name here.
+	 */
+	event = func ? func : "DUMMY_EVENT";
+
+	tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
+				offs, 0 /* maxactive */, 0 /* nargs */,
+				is_return);
+
+	if (IS_ERR(tk)) {
+		pr_info("Failed to allocate trace_probe.(%d)\n",
+			(int)PTR_ERR(tk));
+		return ERR_CAST(tk);
+	}
+
+	init_trace_event_call(tk);
+
+	ptype = trace_kprobe_is_return(tk) ?
+		PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
+	if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	ret = __register_trace_kprobe(tk);
+	if (ret < 0)
+		goto error;
+
+	return trace_probe_event_call(&tk->tp);
+error:
+	free_trace_kprobe(tk);
+	return ERR_PTR(ret);
+}
+
+void destroy_local_trace_kprobe(struct trace_event_call *event_call)
+{
+	struct trace_kprobe *tk;
+
+	tk = trace_kprobe_primary_from_call(event_call);
+	if (unlikely(!tk))
+		return;
+
+	if (trace_probe_is_enabled(&tk->tp)) {
+		WARN_ON(1);
+		return;
+	}
+
+	__unregister_trace_kprobe(tk);
+
+	free_trace_kprobe(tk);
+}
+#endif /* CONFIG_PERF_EVENTS */
+
+static __init void enable_boot_kprobe_events(void)
+{
+	struct trace_array *tr = top_trace_array();
+	struct trace_event_file *file;
+	struct trace_kprobe *tk;
+	struct dyn_event *pos;
+
+	mutex_lock(&event_mutex);
+	for_each_trace_kprobe(tk, pos) {
+		list_for_each_entry(file, &tr->events, list)
+			if (file->event_call == trace_probe_event_call(&tk->tp))
+				trace_event_enable_disable(file, 1, 0);
+	}
+	mutex_unlock(&event_mutex);
+}
+
+static __init void setup_boot_kprobe_events(void)
+{
+	char *p, *cmd = kprobe_boot_events_buf;
+	int ret;
+
+	strreplace(kprobe_boot_events_buf, ',', ' ');
+
+	while (cmd && *cmd != '\0') {
+		p = strchr(cmd, ';');
+		if (p)
+			*p++ = '\0';
+
+		ret = create_or_delete_trace_kprobe(cmd);
+		if (ret)
+			pr_warn("Failed to add event(%d): %s\n", ret, cmd);
+
+		cmd = p;
+	}
+
+	enable_boot_kprobe_events();
+}
+
+/*
+ * Register dynevent at core_initcall. This allows kernel to setup kprobe
+ * events in postcore_initcall without tracefs.
+ */
+static __init int init_kprobe_trace_early(void)
+{
+	int ret;
+
+	ret = dyn_event_register(&trace_kprobe_ops);
+	if (ret)
+		return ret;
+
+	if (register_module_notifier(&trace_kprobe_module_nb))
+		return -EINVAL;
+
+	return 0;
+}
+core_initcall(init_kprobe_trace_early);
+
+/* Make a tracefs interface for controlling probe points */
+static __init int init_kprobe_trace(void)
+{
+	int ret;
+
+	ret = tracing_init_dentry();
+	if (ret)
+		return 0;
+
+	/* Event list interface */
+	trace_create_file("kprobe_events", TRACE_MODE_WRITE,
+			  NULL, NULL, &kprobe_events_ops);
+
+	/* Profile interface */
+	trace_create_file("kprobe_profile", TRACE_MODE_READ,
+			  NULL, NULL, &kprobe_profile_ops);
+
+	setup_boot_kprobe_events();
+
+	return 0;
+}
+fs_initcall(init_kprobe_trace);
+
+
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+static __init struct trace_event_file *
+find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
+{
+	struct trace_event_file *file;
+
+	list_for_each_entry(file, &tr->events, list)
+		if (file->event_call == trace_probe_event_call(&tk->tp))
+			return file;
+
+	return NULL;
+}
+
+/*
+ * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
+ * stage, we can do this lockless.
+ */
+static __init int kprobe_trace_self_tests_init(void)
+{
+	int ret, warn = 0;
+	int (*target)(int, int, int, int, int, int);
+	struct trace_kprobe *tk;
+	struct trace_event_file *file;
+
+	if (tracing_is_disabled())
+		return -ENODEV;
+
+	if (tracing_selftest_disabled)
+		return 0;
+
+	target = kprobe_trace_selftest_target;
+
+	pr_info("Testing kprobe tracing: ");
+
+	ret = create_or_delete_trace_kprobe("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)");
+	if (WARN_ON_ONCE(ret)) {
+		pr_warn("error on probing function entry.\n");
+		warn++;
+	} else {
+		/* Enable trace point */
+		tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
+		if (WARN_ON_ONCE(tk == NULL)) {
+			pr_warn("error on getting new probe.\n");
+			warn++;
+		} else {
+			file = find_trace_probe_file(tk, top_trace_array());
+			if (WARN_ON_ONCE(file == NULL)) {
+				pr_warn("error on getting probe file.\n");
+				warn++;
+			} else
+				enable_trace_kprobe(
+					trace_probe_event_call(&tk->tp), file);
+		}
+	}
+
+	ret = create_or_delete_trace_kprobe("r:testprobe2 kprobe_trace_selftest_target $retval");
+	if (WARN_ON_ONCE(ret)) {
+		pr_warn("error on probing function return.\n");
+		warn++;
+	} else {
+		/* Enable trace point */
+		tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
+		if (WARN_ON_ONCE(tk == NULL)) {
+			pr_warn("error on getting 2nd new probe.\n");
+			warn++;
+		} else {
+			file = find_trace_probe_file(tk, top_trace_array());
+			if (WARN_ON_ONCE(file == NULL)) {
+				pr_warn("error on getting probe file.\n");
+				warn++;
+			} else
+				enable_trace_kprobe(
+					trace_probe_event_call(&tk->tp), file);
+		}
+	}
+
+	if (warn)
+		goto end;
+
+	ret = target(1, 2, 3, 4, 5, 6);
+
+	/*
+	 * Not expecting an error here, the check is only to prevent the
+	 * optimizer from removing the call to target() as otherwise there
+	 * are no side-effects and the call is never performed.
+	 */
+	if (ret != 21)
+		warn++;
+
+	/* Disable trace points before removing it */
+	tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
+	if (WARN_ON_ONCE(tk == NULL)) {
+		pr_warn("error on getting test probe.\n");
+		warn++;
+	} else {
+		if (trace_kprobe_nhit(tk) != 1) {
+			pr_warn("incorrect number of testprobe hits\n");
+			warn++;
+		}
+
+		file = find_trace_probe_file(tk, top_trace_array());
+		if (WARN_ON_ONCE(file == NULL)) {
+			pr_warn("error on getting probe file.\n");
+			warn++;
+		} else
+			disable_trace_kprobe(
+				trace_probe_event_call(&tk->tp), file);
+	}
+
+	tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
+	if (WARN_ON_ONCE(tk == NULL)) {
+		pr_warn("error on getting 2nd test probe.\n");
+		warn++;
+	} else {
+		if (trace_kprobe_nhit(tk) != 1) {
+			pr_warn("incorrect number of testprobe2 hits\n");
+			warn++;
+		}
+
+		file = find_trace_probe_file(tk, top_trace_array());
+		if (WARN_ON_ONCE(file == NULL)) {
+			pr_warn("error on getting probe file.\n");
+			warn++;
+		} else
+			disable_trace_kprobe(
+				trace_probe_event_call(&tk->tp), file);
+	}
+
+	ret = create_or_delete_trace_kprobe("-:testprobe");
+	if (WARN_ON_ONCE(ret)) {
+		pr_warn("error on deleting a probe.\n");
+		warn++;
+	}
+
+	ret = create_or_delete_trace_kprobe("-:testprobe2");
+	if (WARN_ON_ONCE(ret)) {
+		pr_warn("error on deleting a probe.\n");
+		warn++;
+	}
+
+end:
+	ret = dyn_events_release_all(&trace_kprobe_ops);
+	if (WARN_ON_ONCE(ret)) {
+		pr_warn("error on cleaning up probes.\n");
+		warn++;
+	}
+	/*
+	 * Wait for the optimizer work to finish. Otherwise it might fiddle
+	 * with probes in already freed __init text.
+	 */
+	wait_for_kprobe_optimizer();
+	if (warn)
+		pr_cont("NG: Some tests are failed. Please check them.\n");
+	else
+		pr_cont("OK\n");
+	return 0;
+}
+
+late_initcall(kprobe_trace_self_tests_init);
+
+#endif