This source file includes following definitions.
- perf_callchain_entry__sizeof
- perf_callchain_kernel
- perf_callchain_user
- release_callchain_buffers_rcu
- release_callchain_buffers
- alloc_callchain_buffers
- get_callchain_buffers
- put_callchain_buffers
- get_callchain_entry
- put_callchain_entry
- get_perf_callchain
- perf_event_max_stack_handler
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11 #include <linux/perf_event.h>
12 #include <linux/slab.h>
13 #include <linux/sched/task_stack.h>
14
15 #include "internal.h"
16
17 struct callchain_cpus_entries {
18 struct rcu_head rcu_head;
19 struct perf_callchain_entry *cpu_entries[0];
20 };
21
22 int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
23 int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK;
24
25 static inline size_t perf_callchain_entry__sizeof(void)
26 {
27 return (sizeof(struct perf_callchain_entry) +
28 sizeof(__u64) * (sysctl_perf_event_max_stack +
29 sysctl_perf_event_max_contexts_per_stack));
30 }
31
32 static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
33 static atomic_t nr_callchain_events;
34 static DEFINE_MUTEX(callchain_mutex);
35 static struct callchain_cpus_entries *callchain_cpus_entries;
36
37
38 __weak void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
39 struct pt_regs *regs)
40 {
41 }
42
43 __weak void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
44 struct pt_regs *regs)
45 {
46 }
47
48 static void release_callchain_buffers_rcu(struct rcu_head *head)
49 {
50 struct callchain_cpus_entries *entries;
51 int cpu;
52
53 entries = container_of(head, struct callchain_cpus_entries, rcu_head);
54
55 for_each_possible_cpu(cpu)
56 kfree(entries->cpu_entries[cpu]);
57
58 kfree(entries);
59 }
60
61 static void release_callchain_buffers(void)
62 {
63 struct callchain_cpus_entries *entries;
64
65 entries = callchain_cpus_entries;
66 RCU_INIT_POINTER(callchain_cpus_entries, NULL);
67 call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
68 }
69
70 static int alloc_callchain_buffers(void)
71 {
72 int cpu;
73 int size;
74 struct callchain_cpus_entries *entries;
75
76
77
78
79
80
81 size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
82
83 entries = kzalloc(size, GFP_KERNEL);
84 if (!entries)
85 return -ENOMEM;
86
87 size = perf_callchain_entry__sizeof() * PERF_NR_CONTEXTS;
88
89 for_each_possible_cpu(cpu) {
90 entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
91 cpu_to_node(cpu));
92 if (!entries->cpu_entries[cpu])
93 goto fail;
94 }
95
96 rcu_assign_pointer(callchain_cpus_entries, entries);
97
98 return 0;
99
100 fail:
101 for_each_possible_cpu(cpu)
102 kfree(entries->cpu_entries[cpu]);
103 kfree(entries);
104
105 return -ENOMEM;
106 }
107
108 int get_callchain_buffers(int event_max_stack)
109 {
110 int err = 0;
111 int count;
112
113 mutex_lock(&callchain_mutex);
114
115 count = atomic_inc_return(&nr_callchain_events);
116 if (WARN_ON_ONCE(count < 1)) {
117 err = -EINVAL;
118 goto exit;
119 }
120
121
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125
126
127
128 if (event_max_stack > sysctl_perf_event_max_stack) {
129 err = -EOVERFLOW;
130 goto exit;
131 }
132
133 if (count == 1)
134 err = alloc_callchain_buffers();
135 exit:
136 if (err)
137 atomic_dec(&nr_callchain_events);
138
139 mutex_unlock(&callchain_mutex);
140
141 return err;
142 }
143
144 void put_callchain_buffers(void)
145 {
146 if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
147 release_callchain_buffers();
148 mutex_unlock(&callchain_mutex);
149 }
150 }
151
152 static struct perf_callchain_entry *get_callchain_entry(int *rctx)
153 {
154 int cpu;
155 struct callchain_cpus_entries *entries;
156
157 *rctx = get_recursion_context(this_cpu_ptr(callchain_recursion));
158 if (*rctx == -1)
159 return NULL;
160
161 entries = rcu_dereference(callchain_cpus_entries);
162 if (!entries)
163 return NULL;
164
165 cpu = smp_processor_id();
166
167 return (((void *)entries->cpu_entries[cpu]) +
168 (*rctx * perf_callchain_entry__sizeof()));
169 }
170
171 static void
172 put_callchain_entry(int rctx)
173 {
174 put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
175 }
176
177 struct perf_callchain_entry *
178 get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
179 u32 max_stack, bool crosstask, bool add_mark)
180 {
181 struct perf_callchain_entry *entry;
182 struct perf_callchain_entry_ctx ctx;
183 int rctx;
184
185 entry = get_callchain_entry(&rctx);
186 if (rctx == -1)
187 return NULL;
188
189 if (!entry)
190 goto exit_put;
191
192 ctx.entry = entry;
193 ctx.max_stack = max_stack;
194 ctx.nr = entry->nr = init_nr;
195 ctx.contexts = 0;
196 ctx.contexts_maxed = false;
197
198 if (kernel && !user_mode(regs)) {
199 if (add_mark)
200 perf_callchain_store_context(&ctx, PERF_CONTEXT_KERNEL);
201 perf_callchain_kernel(&ctx, regs);
202 }
203
204 if (user) {
205 if (!user_mode(regs)) {
206 if (current->mm)
207 regs = task_pt_regs(current);
208 else
209 regs = NULL;
210 }
211
212 if (regs) {
213 mm_segment_t fs;
214
215 if (crosstask)
216 goto exit_put;
217
218 if (add_mark)
219 perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
220
221 fs = get_fs();
222 set_fs(USER_DS);
223 perf_callchain_user(&ctx, regs);
224 set_fs(fs);
225 }
226 }
227
228 exit_put:
229 put_callchain_entry(rctx);
230
231 return entry;
232 }
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237
238 int perf_event_max_stack_handler(struct ctl_table *table, int write,
239 void __user *buffer, size_t *lenp, loff_t *ppos)
240 {
241 int *value = table->data;
242 int new_value = *value, ret;
243 struct ctl_table new_table = *table;
244
245 new_table.data = &new_value;
246 ret = proc_dointvec_minmax(&new_table, write, buffer, lenp, ppos);
247 if (ret || !write)
248 return ret;
249
250 mutex_lock(&callchain_mutex);
251 if (atomic_read(&nr_callchain_events))
252 ret = -EBUSY;
253 else
254 *value = new_value;
255
256 mutex_unlock(&callchain_mutex);
257
258 return ret;
259 }