1 #include <trace/syscall.h>
2 #include <linux/kernel.h>
3 #include <asm/syscall.h>
4
5 #include "trace_output.h"
6 #include "trace.h"
7
8 /* Keep a counter of the syscall tracing users */
9 static int refcount;
10
11 /* Prevent from races on thread flags toggling */
12 static DEFINE_MUTEX(syscall_trace_lock);
13
14 /* Option to display the parameters types */
15 enum {
16 TRACE_SYSCALLS_OPT_TYPES = 0x1,
17 };
18
19 static struct tracer_opt syscalls_opts[] = {
20 { TRACER_OPT(syscall_arg_type, TRACE_SYSCALLS_OPT_TYPES) },
21 { }
22 };
23
24 static struct tracer_flags syscalls_flags = {
25 .val = 0, /* By default: no parameters types */
26 .opts = syscalls_opts
27 };
28
29 enum print_line_t
30 print_syscall_enter(struct trace_iterator *iter, int flags)
31 {
32 struct trace_seq *s = &iter->seq;
33 struct trace_entry *ent = iter->ent;
34 struct syscall_trace_enter *trace;
35 struct syscall_metadata *entry;
36 int i, ret, syscall;
37
38 trace_assign_type(trace, ent);
39
40 syscall = trace->nr;
41
42 entry = syscall_nr_to_meta(syscall);
43 if (!entry)
44 goto end;
45
46 ret = trace_seq_printf(s, "%s(", entry->name);
47 if (!ret)
48 return TRACE_TYPE_PARTIAL_LINE;
49
50 for (i = 0; i < entry->nb_args; i++) {
51 /* parameter types */
52 if (syscalls_flags.val & TRACE_SYSCALLS_OPT_TYPES) {
53 ret = trace_seq_printf(s, "%s ", entry->types[i]);
54 if (!ret)
55 return TRACE_TYPE_PARTIAL_LINE;
56 }
57 /* parameter values */
58 ret = trace_seq_printf(s, "%s: %lx%s ", entry->args[i],
59 trace->args[i],
60 i == entry->nb_args - 1 ? ")" : ",");
61 if (!ret)
62 return TRACE_TYPE_PARTIAL_LINE;
63 }
64
65 end:
66 trace_seq_printf(s, "\n");
67 return TRACE_TYPE_HANDLED;
68 }
69
70 enum print_line_t
71 print_syscall_exit(struct trace_iterator *iter, int flags)
72 {
73 struct trace_seq *s = &iter->seq;
74 struct trace_entry *ent = iter->ent;
75 struct syscall_trace_exit *trace;
76 int syscall;
77 struct syscall_metadata *entry;
78 int ret;
79
80 trace_assign_type(trace, ent);
81
82 syscall = trace->nr;
83
84 entry = syscall_nr_to_meta(syscall);
85 if (!entry) {
86 trace_seq_printf(s, "\n");
87 return TRACE_TYPE_HANDLED;
88 }
89
90 ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
91 trace->ret);
92 if (!ret)
93 return TRACE_TYPE_PARTIAL_LINE;
94
95 return TRACE_TYPE_HANDLED;
96 }
97
98 void start_ftrace_syscalls(void)
99 {
100 unsigned long flags;
101 struct task_struct *g, *t;
102
103 mutex_lock(&syscall_trace_lock);
104
105 /* Don't enable the flag on the tasks twice */
106 if (++refcount != 1)
107 goto unlock;
108
109 arch_init_ftrace_syscalls();
110 read_lock_irqsave(&tasklist_lock, flags);
111
112 do_each_thread(g, t) {
113 set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
114 } while_each_thread(g, t);
115
116 read_unlock_irqrestore(&tasklist_lock, flags);
117
118 unlock:
119 mutex_unlock(&syscall_trace_lock);
120 }
121
122 void stop_ftrace_syscalls(void)
123 {
124 unsigned long flags;
125 struct task_struct *g, *t;
126
127 mutex_lock(&syscall_trace_lock);
128
129 /* There are perhaps still some users */
130 if (--refcount)
131 goto unlock;
132
133 read_lock_irqsave(&tasklist_lock, flags);
134
135 do_each_thread(g, t) {
136 clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
137 } while_each_thread(g, t);
138
139 read_unlock_irqrestore(&tasklist_lock, flags);
140
141 unlock:
142 mutex_unlock(&syscall_trace_lock);
143 }
144
145 void ftrace_syscall_enter(struct pt_regs *regs)
146 {
147 struct syscall_trace_enter *entry;
148 struct syscall_metadata *sys_data;
149 struct ring_buffer_event *event;
150 int size;
151 int syscall_nr;
152
153 syscall_nr = syscall_get_nr(current, regs);
154
155 sys_data = syscall_nr_to_meta(syscall_nr);
156 if (!sys_data)
157 return;
158
159 size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
160
161 event = trace_current_buffer_lock_reserve(TRACE_SYSCALL_ENTER, size,
162 0, 0);
163 if (!event)
164 return;
165
166 entry = ring_buffer_event_data(event);
167 entry->nr = syscall_nr;
168 syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
169
170 trace_current_buffer_unlock_commit(event, 0, 0);
171 trace_wake_up();
172 }
173
174 void ftrace_syscall_exit(struct pt_regs *regs)
175 {
176 struct syscall_trace_exit *entry;
177 struct syscall_metadata *sys_data;
178 struct ring_buffer_event *event;
179 int syscall_nr;
180
181 syscall_nr = syscall_get_nr(current, regs);
182
183 sys_data = syscall_nr_to_meta(syscall_nr);
184 if (!sys_data)
185 return;
186
187 event = trace_current_buffer_lock_reserve(TRACE_SYSCALL_EXIT,
188 sizeof(*entry), 0, 0);
189 if (!event)
190 return;
191
192 entry = ring_buffer_event_data(event);
193 entry->nr = syscall_nr;
194 entry->ret = syscall_get_return_value(current, regs);
195
196 trace_current_buffer_unlock_commit(event, 0, 0);
197 trace_wake_up();
198 }
199
200 static int init_syscall_tracer(struct trace_array *tr)
201 {
202 start_ftrace_syscalls();
203
204 return 0;
205 }
206
207 static void reset_syscall_tracer(struct trace_array *tr)
208 {
209 stop_ftrace_syscalls();
210 tracing_reset_online_cpus(tr);
211 }
212
213 static struct trace_event syscall_enter_event = {
214 .type = TRACE_SYSCALL_ENTER,
215 .trace = print_syscall_enter,
216 };
217
218 static struct trace_event syscall_exit_event = {
219 .type = TRACE_SYSCALL_EXIT,
220 .trace = print_syscall_exit,
221 };
222
223 static struct tracer syscall_tracer __read_mostly = {
224 .name = "syscall",
225 .init = init_syscall_tracer,
226 .reset = reset_syscall_tracer,
227 .flags = &syscalls_flags,
228 };
229
230 __init int register_ftrace_syscalls(void)
231 {
232 int ret;
233
234 ret = register_ftrace_event(&syscall_enter_event);
235 if (!ret) {
236 printk(KERN_WARNING "event %d failed to register\n",
237 syscall_enter_event.type);
238 WARN_ON_ONCE(1);
239 }
240
241 ret = register_ftrace_event(&syscall_exit_event);
242 if (!ret) {
243 printk(KERN_WARNING "event %d failed to register\n",
244 syscall_exit_event.type);
245 WARN_ON_ONCE(1);
246 }
247
248 return register_tracer(&syscall_tracer);
249 }
250 device_initcall(register_ftrace_syscalls);
251
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