#include <trace/syscall.h>

  #include <trace/events/syscalls.h>

  #include <linux/slab.h>

  #include <linux/kernel.h>

  #include <linux/module.h>	/* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */

  #include <linux/ftrace.h>

  #include <linux/perf_event.h>

  #include <asm/syscall.h>
  
  #include "trace_output.h"
  #include "trace.h"

  static DEFINE_MUTEX(syscall_trace_lock);

  static int sys_refcount_enter;
  static int sys_refcount_exit;

  static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
  static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);

  static int syscall_enter_register(struct ftrace_event_call *event,
  				 enum trace_reg type);
  static int syscall_exit_register(struct ftrace_event_call *event,
  				 enum trace_reg type);

  static int syscall_enter_define_fields(struct ftrace_event_call *call);
  static int syscall_exit_define_fields(struct ftrace_event_call *call);
  
  static struct list_head *
  syscall_get_enter_fields(struct ftrace_event_call *call)
  {
  	struct syscall_metadata *entry = call->data;
  
  	return &entry->enter_fields;
  }

  struct trace_event_functions enter_syscall_print_funcs = {

  	.trace		= print_syscall_enter,

  };
  
  struct trace_event_functions exit_syscall_print_funcs = {

  	.trace		= print_syscall_exit,

  };

  struct ftrace_event_class event_class_syscall_enter = {

  	.system		= "syscalls",
  	.reg		= syscall_enter_register,
  	.define_fields	= syscall_enter_define_fields,
  	.get_fields	= syscall_get_enter_fields,
  	.raw_init	= init_syscall_trace,

  };
  
  struct ftrace_event_class event_class_syscall_exit = {

  	.system		= "syscalls",
  	.reg		= syscall_exit_register,
  	.define_fields	= syscall_exit_define_fields,
  	.fields		= LIST_HEAD_INIT(event_class_syscall_exit.fields),
  	.raw_init	= init_syscall_trace,

  };

  extern struct syscall_metadata *__start_syscalls_metadata[];
  extern struct syscall_metadata *__stop_syscalls_metadata[];

  
  static struct syscall_metadata **syscalls_metadata;

  #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
  static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
  {
  	/*
  	 * Only compare after the "sys" prefix. Archs that use
  	 * syscall wrappers may have syscalls symbols aliases prefixed
  	 * with "SyS" instead of "sys", leading to an unwanted
  	 * mismatch.
  	 */
  	return !strcmp(sym + 3, name + 3);
  }
  #endif

  static __init struct syscall_metadata *
  find_syscall_meta(unsigned long syscall)

  {

  	struct syscall_metadata **start;
  	struct syscall_metadata **stop;

  	char str[KSYM_SYMBOL_LEN];

  	start = __start_syscalls_metadata;
  	stop = __stop_syscalls_metadata;

  	kallsyms_lookup(syscall, NULL, NULL, NULL, str);

  	if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
  		return NULL;

  	for ( ; start < stop; start++) {

  		if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))

  			return *start;

  	}
  	return NULL;
  }
  
  static struct syscall_metadata *syscall_nr_to_meta(int nr)
  {
  	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
  		return NULL;
  
  	return syscalls_metadata[nr];
  }

  enum print_line_t

  print_syscall_enter(struct trace_iterator *iter, int flags,
  		    struct trace_event *event)

  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *ent = iter->ent;
  	struct syscall_trace_enter *trace;
  	struct syscall_metadata *entry;
  	int i, ret, syscall;

  	trace = (typeof(trace))ent;

  	syscall = trace->nr;

  	entry = syscall_nr_to_meta(syscall);

  	if (!entry)
  		goto end;

  	if (entry->enter_event->event.type != ent->type) {

  		WARN_ON_ONCE(1);
  		goto end;
  	}

  	ret = trace_seq_printf(s, "%s(", entry->name);
  	if (!ret)
  		return TRACE_TYPE_PARTIAL_LINE;
  
  	for (i = 0; i < entry->nb_args; i++) {
  		/* parameter types */

  		if (trace_flags & TRACE_ITER_VERBOSE) {

  			ret = trace_seq_printf(s, "%s ", entry->types[i]);
  			if (!ret)
  				return TRACE_TYPE_PARTIAL_LINE;
  		}
  		/* parameter values */

  		ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],

  				       trace->args[i],

  				       i == entry->nb_args - 1 ? "" : ", ");

  		if (!ret)
  			return TRACE_TYPE_PARTIAL_LINE;
  	}

  	ret = trace_seq_putc(s, ')');
  	if (!ret)
  		return TRACE_TYPE_PARTIAL_LINE;

  end:

  	ret =  trace_seq_putc(s, '
  ');
  	if (!ret)
  		return TRACE_TYPE_PARTIAL_LINE;

  	return TRACE_TYPE_HANDLED;
  }
  
  enum print_line_t

  print_syscall_exit(struct trace_iterator *iter, int flags,
  		   struct trace_event *event)

  {
  	struct trace_seq *s = &iter->seq;
  	struct trace_entry *ent = iter->ent;
  	struct syscall_trace_exit *trace;
  	int syscall;
  	struct syscall_metadata *entry;
  	int ret;

  	trace = (typeof(trace))ent;

  	syscall = trace->nr;

  	entry = syscall_nr_to_meta(syscall);

  	if (!entry) {
  		trace_seq_printf(s, "
  ");
  		return TRACE_TYPE_HANDLED;
  	}

  	if (entry->exit_event->event.type != ent->type) {

  		WARN_ON_ONCE(1);
  		return TRACE_TYPE_UNHANDLED;
  	}

  	ret = trace_seq_printf(s, "%s -> 0x%lx
  ", entry->name,
  				trace->ret);
  	if (!ret)
  		return TRACE_TYPE_PARTIAL_LINE;
  
  	return TRACE_TYPE_HANDLED;
  }

  extern char *__bad_type_size(void);
  
  #define SYSCALL_FIELD(type, name)					\
  	sizeof(type) != sizeof(trace.name) ?				\
  		__bad_type_size() :					\

  		#type, #name, offsetof(typeof(trace), name),		\
  		sizeof(trace.name), is_signed_type(type)

  static
  int  __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
  {
  	int i;
  	int pos = 0;
  
  	/* When len=0, we just calculate the needed length */
  #define LEN_OR_ZERO (len ? len - pos : 0)
  
  	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
  	for (i = 0; i < entry->nb_args; i++) {
  		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
  				entry->args[i], sizeof(unsigned long),
  				i == entry->nb_args - 1 ? "" : ", ");
  	}
  	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
  
  	for (i = 0; i < entry->nb_args; i++) {
  		pos += snprintf(buf + pos, LEN_OR_ZERO,
  				", ((unsigned long)(REC->%s))", entry->args[i]);
  	}
  
  #undef LEN_OR_ZERO
  
  	/* return the length of print_fmt */
  	return pos;
  }
  
  static int set_syscall_print_fmt(struct ftrace_event_call *call)
  {
  	char *print_fmt;
  	int len;
  	struct syscall_metadata *entry = call->data;
  
  	if (entry->enter_event != call) {
  		call->print_fmt = "\"0x%lx\", REC->ret";
  		return 0;
  	}
  
  	/* First: called with 0 length to calculate the needed length */
  	len = __set_enter_print_fmt(entry, NULL, 0);
  
  	print_fmt = kmalloc(len + 1, GFP_KERNEL);
  	if (!print_fmt)
  		return -ENOMEM;
  
  	/* Second: actually write the @print_fmt */
  	__set_enter_print_fmt(entry, print_fmt, len + 1);
  	call->print_fmt = print_fmt;
  
  	return 0;
  }
  
  static void free_syscall_print_fmt(struct ftrace_event_call *call)
  {
  	struct syscall_metadata *entry = call->data;
  
  	if (entry->enter_event == call)
  		kfree(call->print_fmt);
  }

  static int syscall_enter_define_fields(struct ftrace_event_call *call)

  {
  	struct syscall_trace_enter trace;

  	struct syscall_metadata *meta = call->data;

  	int ret;

  	int i;
  	int offset = offsetof(typeof(trace), args);

  	ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
  	if (ret)
  		return ret;

  	for (i = 0; i < meta->nb_args; i++) {

  		ret = trace_define_field(call, meta->types[i],
  					 meta->args[i], offset,

  					 sizeof(unsigned long), 0,
  					 FILTER_OTHER);

  		offset += sizeof(unsigned long);
  	}
  
  	return ret;
  }

  static int syscall_exit_define_fields(struct ftrace_event_call *call)

  {
  	struct syscall_trace_exit trace;
  	int ret;

  	ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
  	if (ret)
  		return ret;

  	ret = trace_define_field(call, SYSCALL_FIELD(long, ret),

  				 FILTER_OTHER);

  
  	return ret;
  }

  void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)

  {

  	struct syscall_trace_enter *entry;
  	struct syscall_metadata *sys_data;
  	struct ring_buffer_event *event;

  	struct ring_buffer *buffer;

  	int size;

  	int syscall_nr;
  
  	syscall_nr = syscall_get_nr(current, regs);

  	if (syscall_nr < 0)
  		return;

  	if (!test_bit(syscall_nr, enabled_enter_syscalls))
  		return;

  	sys_data = syscall_nr_to_meta(syscall_nr);
  	if (!sys_data)
  		return;
  
  	size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;

  	event = trace_current_buffer_lock_reserve(&buffer,

  			sys_data->enter_event->event.type, size, 0, 0);

  	if (!event)
  		return;
  
  	entry = ring_buffer_event_data(event);
  	entry->nr = syscall_nr;
  	syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);

  	if (!filter_current_check_discard(buffer, sys_data->enter_event,
  					  entry, event))
  		trace_current_buffer_unlock_commit(buffer, event, 0, 0);

  }

  void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)

  {

  	struct syscall_trace_exit *entry;
  	struct syscall_metadata *sys_data;
  	struct ring_buffer_event *event;

  	struct ring_buffer *buffer;

  	int syscall_nr;
  
  	syscall_nr = syscall_get_nr(current, regs);

  	if (syscall_nr < 0)
  		return;

  	if (!test_bit(syscall_nr, enabled_exit_syscalls))
  		return;

  	sys_data = syscall_nr_to_meta(syscall_nr);
  	if (!sys_data)
  		return;

  	event = trace_current_buffer_lock_reserve(&buffer,

  			sys_data->exit_event->event.type, sizeof(*entry), 0, 0);

  	if (!event)
  		return;
  
  	entry = ring_buffer_event_data(event);
  	entry->nr = syscall_nr;
  	entry->ret = syscall_get_return_value(current, regs);

  	if (!filter_current_check_discard(buffer, sys_data->exit_event,
  					  entry, event))
  		trace_current_buffer_unlock_commit(buffer, event, 0, 0);

  }

  int reg_event_syscall_enter(struct ftrace_event_call *call)

  {

  	int ret = 0;
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))

  		return -ENOSYS;
  	mutex_lock(&syscall_trace_lock);
  	if (!sys_refcount_enter)

  		ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);

  	if (!ret) {

  		set_bit(num, enabled_enter_syscalls);
  		sys_refcount_enter++;
  	}
  	mutex_unlock(&syscall_trace_lock);
  	return ret;

  }

  void unreg_event_syscall_enter(struct ftrace_event_call *call)

  {

  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))

  		return;
  	mutex_lock(&syscall_trace_lock);
  	sys_refcount_enter--;
  	clear_bit(num, enabled_enter_syscalls);
  	if (!sys_refcount_enter)

  		unregister_trace_sys_enter(ftrace_syscall_enter, NULL);

  	mutex_unlock(&syscall_trace_lock);
  }

  int reg_event_syscall_exit(struct ftrace_event_call *call)

  {

  	int ret = 0;
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))

  		return -ENOSYS;
  	mutex_lock(&syscall_trace_lock);
  	if (!sys_refcount_exit)

  		ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);

  	if (!ret) {

  		set_bit(num, enabled_exit_syscalls);
  		sys_refcount_exit++;

  	}

  	mutex_unlock(&syscall_trace_lock);
  	return ret;
  }

  void unreg_event_syscall_exit(struct ftrace_event_call *call)

  {
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))

  		return;
  	mutex_lock(&syscall_trace_lock);
  	sys_refcount_exit--;
  	clear_bit(num, enabled_exit_syscalls);
  	if (!sys_refcount_exit)

  		unregister_trace_sys_exit(ftrace_syscall_exit, NULL);

  	mutex_unlock(&syscall_trace_lock);

  }

  int init_syscall_trace(struct ftrace_event_call *call)
  {
  	int id;

  	int num;
  
  	num = ((struct syscall_metadata *)call->data)->syscall_nr;
  	if (num < 0 || num >= NR_syscalls) {
  		pr_debug("syscall %s metadata not mapped, disabling ftrace event
  ",
  				((struct syscall_metadata *)call->data)->name);
  		return -ENOSYS;
  	}

  	if (set_syscall_print_fmt(call) < 0)
  		return -ENOMEM;

  	id = trace_event_raw_init(call);
  
  	if (id < 0) {

  		free_syscall_print_fmt(call);

  		return id;

  	}

  
  	return id;

  }

  unsigned long __init __weak arch_syscall_addr(int nr)

  {
  	return (unsigned long)sys_call_table[nr];
  }

  int __init init_ftrace_syscalls(void)
  {
  	struct syscall_metadata *meta;
  	unsigned long addr;
  	int i;
  
  	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
  					NR_syscalls, GFP_KERNEL);
  	if (!syscalls_metadata) {
  		WARN_ON(1);
  		return -ENOMEM;
  	}
  
  	for (i = 0; i < NR_syscalls; i++) {
  		addr = arch_syscall_addr(i);
  		meta = find_syscall_meta(addr);

  		if (!meta)
  			continue;
  
  		meta->syscall_nr = i;

  		syscalls_metadata[i] = meta;
  	}
  
  	return 0;
  }
  core_initcall(init_ftrace_syscalls);

  #ifdef CONFIG_PERF_EVENTS

  static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
  static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
  static int sys_perf_refcount_enter;
  static int sys_perf_refcount_exit;

  static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)

  {
  	struct syscall_metadata *sys_data;

  	struct syscall_trace_enter *rec;

  	struct hlist_head *head;

  	int syscall_nr;

  	int rctx;

  	int size;

  
  	syscall_nr = syscall_get_nr(current, regs);

  	if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))

  		return;
  
  	sys_data = syscall_nr_to_meta(syscall_nr);
  	if (!sys_data)
  		return;

  	/* get the size after alignment with the u32 buffer size field */
  	size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
  	size = ALIGN(size + sizeof(u32), sizeof(u64));
  	size -= sizeof(u32);

  	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
  		      "perf buffer not large enough"))

  		return;

  	rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,

  				sys_data->enter_event->event.type, regs, &rctx);

  	if (!rec)
  		return;

  	rec->nr = syscall_nr;
  	syscall_get_arguments(current, regs, 0, sys_data->nb_args,
  			       (unsigned long *)&rec->args);

  	head = this_cpu_ptr(sys_data->enter_event->perf_events);

  	perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);

  }

  int perf_sysenter_enable(struct ftrace_event_call *call)

  {
  	int ret = 0;
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  
  	mutex_lock(&syscall_trace_lock);

  	if (!sys_perf_refcount_enter)

  		ret = register_trace_sys_enter(perf_syscall_enter, NULL);

  	if (ret) {
  		pr_info("event trace: Could not activate"
  				"syscall entry trace point");
  	} else {

  		set_bit(num, enabled_perf_enter_syscalls);
  		sys_perf_refcount_enter++;

  	}
  	mutex_unlock(&syscall_trace_lock);
  	return ret;
  }

  void perf_sysenter_disable(struct ftrace_event_call *call)

  {
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  
  	mutex_lock(&syscall_trace_lock);

  	sys_perf_refcount_enter--;
  	clear_bit(num, enabled_perf_enter_syscalls);
  	if (!sys_perf_refcount_enter)

  		unregister_trace_sys_enter(perf_syscall_enter, NULL);

  	mutex_unlock(&syscall_trace_lock);
  }

  static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)

  {
  	struct syscall_metadata *sys_data;

  	struct syscall_trace_exit *rec;

  	struct hlist_head *head;

  	int syscall_nr;

  	int rctx;

  	int size;

  
  	syscall_nr = syscall_get_nr(current, regs);

  	if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))

  		return;
  
  	sys_data = syscall_nr_to_meta(syscall_nr);
  	if (!sys_data)
  		return;

  	/* We can probably do that at build time */
  	size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
  	size -= sizeof(u32);

  	/*
  	 * Impossible, but be paranoid with the future
  	 * How to put this check outside runtime?
  	 */

  	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
  		"exit event has grown above perf buffer size"))

  		return;

  	rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,

  				sys_data->exit_event->event.type, regs, &rctx);

  	if (!rec)
  		return;

  	rec->nr = syscall_nr;
  	rec->ret = syscall_get_return_value(current, regs);

  	head = this_cpu_ptr(sys_data->exit_event->perf_events);

  	perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);

  }

  int perf_sysexit_enable(struct ftrace_event_call *call)

  {
  	int ret = 0;
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  
  	mutex_lock(&syscall_trace_lock);

  	if (!sys_perf_refcount_exit)

  		ret = register_trace_sys_exit(perf_syscall_exit, NULL);

  	if (ret) {
  		pr_info("event trace: Could not activate"

  				"syscall exit trace point");

  	} else {

  		set_bit(num, enabled_perf_exit_syscalls);
  		sys_perf_refcount_exit++;

  	}
  	mutex_unlock(&syscall_trace_lock);
  	return ret;
  }

  void perf_sysexit_disable(struct ftrace_event_call *call)

  {
  	int num;

  	num = ((struct syscall_metadata *)call->data)->syscall_nr;

  
  	mutex_lock(&syscall_trace_lock);

  	sys_perf_refcount_exit--;
  	clear_bit(num, enabled_perf_exit_syscalls);
  	if (!sys_perf_refcount_exit)

  		unregister_trace_sys_exit(perf_syscall_exit, NULL);

  	mutex_unlock(&syscall_trace_lock);
  }

  #endif /* CONFIG_PERF_EVENTS */

  static int syscall_enter_register(struct ftrace_event_call *event,
  				 enum trace_reg type)
  {
  	switch (type) {
  	case TRACE_REG_REGISTER:
  		return reg_event_syscall_enter(event);
  	case TRACE_REG_UNREGISTER:
  		unreg_event_syscall_enter(event);
  		return 0;
  
  #ifdef CONFIG_PERF_EVENTS
  	case TRACE_REG_PERF_REGISTER:
  		return perf_sysenter_enable(event);
  	case TRACE_REG_PERF_UNREGISTER:
  		perf_sysenter_disable(event);
  		return 0;
  #endif
  	}
  	return 0;
  }
  
  static int syscall_exit_register(struct ftrace_event_call *event,
  				 enum trace_reg type)
  {
  	switch (type) {
  	case TRACE_REG_REGISTER:
  		return reg_event_syscall_exit(event);
  	case TRACE_REG_UNREGISTER:
  		unreg_event_syscall_exit(event);
  		return 0;
  
  #ifdef CONFIG_PERF_EVENTS
  	case TRACE_REG_PERF_REGISTER:
  		return perf_sysexit_enable(event);
  	case TRACE_REG_PERF_UNREGISTER:
  		perf_sysexit_disable(event);
  		return 0;
  #endif
  	}
  	return 0;
  }