// 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/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"

  #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 0;
  }
  __setup("kprobe_event=", set_kprobe_boot_events);

  static int trace_kprobe_create(int argc, const char **argv);
  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)))

  #define SIZEOF_TRACE_KPROBE(n)				\
  	(offsetof(struct trace_kprobe, tp.args) +	\

  	(sizeof(struct probe_arg) * (n)))

  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';
  	mutex_lock(&module_mutex);
  	ret = !!find_module(tk->symbol);
  	mutex_unlock(&module_mutex);
  	*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 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) : 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(SIZEOF_TRACE_KPROBE(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_probe *pos;
  	struct trace_kprobe *tk;
  
  	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
  		tk = container_of(pos, struct trace_kprobe, tp);
  		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 *pos, *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(pos, trace_probe_probe_list(tp), list) {
  		tk = container_of(pos, struct trace_kprobe, tp);
  		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
  ",
  			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;

  	/* 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;
  	struct trace_probe *pos;
  	int i;
  
  	list_for_each_entry(pos, &tpe->probes, list) {
  		orig = container_of(pos, struct trace_kprobe, tp);
  		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.
  ");
  		ret = 0;
  	}
  
  	if (ret)
  		trace_probe_unlink(&tk->tp);
  	else
  		dyn_event_add(&tk->devent);
  
  	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) {

  		pr_warn("Failed to register probe event(%d)
  ", 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.
  ");
  		ret = 0;
  	}

  	if (ret < 0)

  		unregister_kprobe_event(tk);

  	else

  		dyn_event_add(&tk->devent);

  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
  ",

  					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 */
  };

  /* Convert certain expected symbols into '_' when generating event names */
  static inline void sanitize_event_name(char *name)
  {
  	while (*name++ != '\0')
  		if (*name == ':' || *name == '.')
  			*name = '_';
  }

  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;

  	int maxactive = 0;

  	long offset = 0;

  	void *addr = NULL;

  	char buf[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;

  		if (kprobe_on_func_entry(NULL, symbol, offset))
  			flags |= TPARG_FL_FENTRY;
  		if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {

  			trace_probe_log_err(0, BAD_RETPROBE);
  			goto parse_error;

  		}

  	}

  	trace_probe_log_set_index(0);

  	if (event) {

  		ret = traceprobe_parse_event_name(&event, &group, buf,
  						  event - argv[0]);

  		if (ret)

  			goto parse_error;

  	} else {

  		/* 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++) {

  		tmp = kstrdup(argv[i], GFP_KERNEL);
  		if (!tmp) {

  			ret = -ENOMEM;

  			goto error;
  		}

  		trace_probe_log_set_index(i + 2);

  		ret = traceprobe_parse_probe_arg(&tk->tp, i, tmp, flags);
  		kfree(tmp);

  		if (ret)

  			goto error;	/* This can be -ENOMEM */

  	}

  	ret = traceprobe_set_print_fmt(&tk->tp, is_return);
  	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 create_or_delete_trace_kprobe(int argc, char **argv)

  {

  	int ret;

  	if (argv[0][0] == '-')
  		return dyn_event_release(argc, argv, &trace_kprobe_ops);

  	ret = trace_kprobe_create(argc, (const char **)argv);
  	return ret == -ECANCELED ? -EINVAL : ret;

  }

  static int trace_kprobe_run_command(struct dynevent_cmd *cmd)

  {

  	return trace_run_command(cmd->seq.buffer, create_or_delete_trace_kprobe);

  }
  
  /**
   * 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
   * @name: The name of the kprobe event
   * @loc: The location of the kprobe event
   * @kretprobe: Is this a return probe?
   * @args: 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
   * @args: 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 trace_run_command(buf, create_or_delete_trace_kprobe);
  }
  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, '
  ');

  	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;

  	if (!is_trace_kprobe(ev))
  		return 0;

  	tk = to_trace_kprobe(ev);

  	seq_printf(m, "  %-44s %15lu %15lu
  ",

  		   trace_probe_name(&tk->tp),

  		   trace_kprobe_nhit(tk),

  		   tk->rp.kp.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)
  {
  	const void __user *uaddr =  (__force const void __user *)addr;
  
  	return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
  }
  
  /* Return the length of string -- including null terminal byte */
  static nokprobe_inline int

  fetch_store_strlen(unsigned long addr)

  {

  	int ret, len = 0;
  	u8 c;

  #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
  	if (addr < TASK_SIZE)
  		return fetch_store_strlen_user(addr);
  #endif

  	do {

  		ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);

  		len++;
  	} while (c && ret == 0 && len < MAX_STRING_SIZE);

  	return (ret < 0) ? ret : len;

  }
  
  /*

   * 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)

  {

  	const void __user *uaddr =  (__force const void __user *)addr;

  	int maxlen = get_loc_len(*(u32 *)dest);

  	void *__dest;

  	long ret;

  	if (unlikely(!maxlen))
  		return -ENOMEM;

  
  	__dest = get_loc_data(dest, base);

  	ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);

  	if (ret >= 0)
  		*(u32 *)dest = make_data_loc(ret, __dest - base);
  
  	return ret;
  }

  /*

   * 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)

  {

  	int maxlen = get_loc_len(*(u32 *)dest);
  	void *__dest;
  	long ret;

  #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
  	if ((unsigned long)addr < TASK_SIZE)
  		return fetch_store_string_user(addr, dest, base);
  #endif

  	if (unlikely(!maxlen))
  		return -ENOMEM;
  
  	__dest = get_loc_data(dest, base);

  	/*
  	 * Try to get string again, since the string can be changed while
  	 * probing.
  	 */
  	ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);

  	if (ret >= 0)

  		*(u32 *)dest = make_data_loc(ret, __dest - base);

  	return ret;

  }

  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, struct pt_regs *regs, void *dest,

  		   void *base)

  {
  	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;

  	local_save_flags(fbuffer.flags);
  	fbuffer.pc = preempt_count();
  	fbuffer.trace_file = trace_file;

  	dsize = __get_data_size(&tk->tp, regs);

  	fbuffer.event =
  		trace_event_buffer_lock_reserve(&fbuffer.buffer, trace_file,
  					call->event.type,
  					sizeof(*entry) + tk->tp.size + dsize,
  					fbuffer.flags, fbuffer.pc);
  	if (!fbuffer.event)

  		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;

  	local_save_flags(fbuffer.flags);
  	fbuffer.pc = preempt_count();
  	fbuffer.trace_file = trace_file;

  	dsize = __get_data_size(&tk->tp, regs);

  	fbuffer.event =
  		trace_event_buffer_lock_reserve(&fbuffer.buffer, trace_file,
  					call->event.type,
  					sizeof(*entry) + tk->tp.size + dsize,
  					fbuffer.flags, fbuffer.pc);
  	if (!fbuffer.event)

  		return;

  	fbuffer.regs = regs;
  	entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);

  	entry->func = (unsigned long)tk->rp.kp.addr;

  	entry->ret_ip = (unsigned long)ri->ret_addr;

  	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, ')');