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1/*
2 * Performance events callchain code, extracted from core.c:
3 *
4 * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
5 * Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
6 * Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
7 * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
8 *
9 * For licensing details see kernel-base/COPYING
10 */
11
12#include <linux/perf_event.h>
13#include <linux/slab.h>
14#include "internal.h"
15
16struct callchain_cpus_entries {
17 struct rcu_head rcu_head;
18 struct perf_callchain_entry *cpu_entries[0];
19};
20
21int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
22int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK;
23
24static inline size_t perf_callchain_entry__sizeof(void)
25{
26 return (sizeof(struct perf_callchain_entry) +
27 sizeof(__u64) * (sysctl_perf_event_max_stack +
28 sysctl_perf_event_max_contexts_per_stack));
29}
30
31static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
32static atomic_t nr_callchain_events;
33static DEFINE_MUTEX(callchain_mutex);
34static struct callchain_cpus_entries *callchain_cpus_entries;
35
36
37__weak void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
38 struct pt_regs *regs)
39{
40}
41
42__weak void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
43 struct pt_regs *regs)
44{
45}
46
47static void release_callchain_buffers_rcu(struct rcu_head *head)
48{
49 struct callchain_cpus_entries *entries;
50 int cpu;
51
52 entries = container_of(head, struct callchain_cpus_entries, rcu_head);
53
54 for_each_possible_cpu(cpu)
55 kfree(entries->cpu_entries[cpu]);
56
57 kfree(entries);
58}
59
60static void release_callchain_buffers(void)
61{
62 struct callchain_cpus_entries *entries;
63
64 entries = callchain_cpus_entries;
65 RCU_INIT_POINTER(callchain_cpus_entries, NULL);
66 call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
67}
68
69static int alloc_callchain_buffers(void)
70{
71 int cpu;
72 int size;
73 struct callchain_cpus_entries *entries;
74
75 /*
76 * We can't use the percpu allocation API for data that can be
77 * accessed from NMI. Use a temporary manual per cpu allocation
78 * until that gets sorted out.
79 */
80 size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
81
82 entries = kzalloc(size, GFP_KERNEL);
83 if (!entries)
84 return -ENOMEM;
85
86 size = perf_callchain_entry__sizeof() * PERF_NR_CONTEXTS;
87
88 for_each_possible_cpu(cpu) {
89 entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
90 cpu_to_node(cpu));
91 if (!entries->cpu_entries[cpu])
92 goto fail;
93 }
94
95 rcu_assign_pointer(callchain_cpus_entries, entries);
96
97 return 0;
98
99fail:
100 for_each_possible_cpu(cpu)
101 kfree(entries->cpu_entries[cpu]);
102 kfree(entries);
103
104 return -ENOMEM;
105}
106
107int get_callchain_buffers(int event_max_stack)
108{
109 int err = 0;
110 int count;
111
112 mutex_lock(&callchain_mutex);
113
114 count = atomic_inc_return(&nr_callchain_events);
115 if (WARN_ON_ONCE(count < 1)) {
116 err = -EINVAL;
117 goto exit;
118 }
119
120 if (count > 1) {
121 /* If the allocation failed, give up */
122 if (!callchain_cpus_entries)
123 err = -ENOMEM;
124 /*
125 * If requesting per event more than the global cap,
126 * return a different error to help userspace figure
127 * this out.
128 *
129 * And also do it here so that we have &callchain_mutex held.
130 */
131 if (event_max_stack > sysctl_perf_event_max_stack)
132 err = -EOVERFLOW;
133 goto exit;
134 }
135
136 err = alloc_callchain_buffers();
137exit:
138 if (err)
139 atomic_dec(&nr_callchain_events);
140
141 mutex_unlock(&callchain_mutex);
142
143 return err;
144}
145
146void put_callchain_buffers(void)
147{
148 if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
149 release_callchain_buffers();
150 mutex_unlock(&callchain_mutex);
151 }
152}
153
154static struct perf_callchain_entry *get_callchain_entry(int *rctx)
155{
156 int cpu;
157 struct callchain_cpus_entries *entries;
158
159 *rctx = get_recursion_context(this_cpu_ptr(callchain_recursion));
160 if (*rctx == -1)
161 return NULL;
162
163 entries = rcu_dereference(callchain_cpus_entries);
164 if (!entries)
165 return NULL;
166
167 cpu = smp_processor_id();
168
169 return (((void *)entries->cpu_entries[cpu]) +
170 (*rctx * perf_callchain_entry__sizeof()));
171}
172
173static void
174put_callchain_entry(int rctx)
175{
176 put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
177}
178
179struct perf_callchain_entry *
180perf_callchain(struct perf_event *event, struct pt_regs *regs)
181{
182 bool kernel = !event->attr.exclude_callchain_kernel;
183 bool user = !event->attr.exclude_callchain_user;
184 /* Disallow cross-task user callchains. */
185 bool crosstask = event->ctx->task && event->ctx->task != current;
186 const u32 max_stack = event->attr.sample_max_stack;
187
188 if (!kernel && !user)
189 return NULL;
190
191 return get_perf_callchain(regs, 0, kernel, user, max_stack, crosstask, true);
192}
193
194struct perf_callchain_entry *
195get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
196 u32 max_stack, bool crosstask, bool add_mark)
197{
198 struct perf_callchain_entry *entry;
199 struct perf_callchain_entry_ctx ctx;
200 int rctx;
201
202 entry = get_callchain_entry(&rctx);
203 if (rctx == -1)
204 return NULL;
205
206 if (!entry)
207 goto exit_put;
208
209 ctx.entry = entry;
210 ctx.max_stack = max_stack;
211 ctx.nr = entry->nr = init_nr;
212 ctx.contexts = 0;
213 ctx.contexts_maxed = false;
214
215 if (kernel && !user_mode(regs)) {
216 if (add_mark)
217 perf_callchain_store_context(&ctx, PERF_CONTEXT_KERNEL);
218 perf_callchain_kernel(&ctx, regs);
219 }
220
221 if (user) {
222 if (!user_mode(regs)) {
223 if (current->mm)
224 regs = task_pt_regs(current);
225 else
226 regs = NULL;
227 }
228
229 if (regs) {
230 if (crosstask)
231 goto exit_put;
232
233 if (add_mark)
234 perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
235 perf_callchain_user(&ctx, regs);
236 }
237 }
238
239exit_put:
240 put_callchain_entry(rctx);
241
242 return entry;
243}
244
245/*
246 * Used for sysctl_perf_event_max_stack and
247 * sysctl_perf_event_max_contexts_per_stack.
248 */
249int perf_event_max_stack_handler(struct ctl_table *table, int write,
250 void __user *buffer, size_t *lenp, loff_t *ppos)
251{
252 int *value = table->data;
253 int new_value = *value, ret;
254 struct ctl_table new_table = *table;
255
256 new_table.data = &new_value;
257 ret = proc_dointvec_minmax(&new_table, write, buffer, lenp, ppos);
258 if (ret || !write)
259 return ret;
260
261 mutex_lock(&callchain_mutex);
262 if (atomic_read(&nr_callchain_events))
263 ret = -EBUSY;
264 else
265 *value = new_value;
266
267 mutex_unlock(&callchain_mutex);
268
269 return ret;
270}
1/*
2 * Performance events callchain code, extracted from core.c:
3 *
4 * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
5 * Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
6 * Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
7 * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
8 *
9 * For licensing details see kernel-base/COPYING
10 */
11
12#include <linux/perf_event.h>
13#include <linux/slab.h>
14#include <linux/sched/task_stack.h>
15
16#include "internal.h"
17
18struct callchain_cpus_entries {
19 struct rcu_head rcu_head;
20 struct perf_callchain_entry *cpu_entries[0];
21};
22
23int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
24int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK;
25
26static inline size_t perf_callchain_entry__sizeof(void)
27{
28 return (sizeof(struct perf_callchain_entry) +
29 sizeof(__u64) * (sysctl_perf_event_max_stack +
30 sysctl_perf_event_max_contexts_per_stack));
31}
32
33static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
34static atomic_t nr_callchain_events;
35static DEFINE_MUTEX(callchain_mutex);
36static struct callchain_cpus_entries *callchain_cpus_entries;
37
38
39__weak void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
40 struct pt_regs *regs)
41{
42}
43
44__weak void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
45 struct pt_regs *regs)
46{
47}
48
49static void release_callchain_buffers_rcu(struct rcu_head *head)
50{
51 struct callchain_cpus_entries *entries;
52 int cpu;
53
54 entries = container_of(head, struct callchain_cpus_entries, rcu_head);
55
56 for_each_possible_cpu(cpu)
57 kfree(entries->cpu_entries[cpu]);
58
59 kfree(entries);
60}
61
62static void release_callchain_buffers(void)
63{
64 struct callchain_cpus_entries *entries;
65
66 entries = callchain_cpus_entries;
67 RCU_INIT_POINTER(callchain_cpus_entries, NULL);
68 call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
69}
70
71static int alloc_callchain_buffers(void)
72{
73 int cpu;
74 int size;
75 struct callchain_cpus_entries *entries;
76
77 /*
78 * We can't use the percpu allocation API for data that can be
79 * accessed from NMI. Use a temporary manual per cpu allocation
80 * until that gets sorted out.
81 */
82 size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
83
84 entries = kzalloc(size, GFP_KERNEL);
85 if (!entries)
86 return -ENOMEM;
87
88 size = perf_callchain_entry__sizeof() * PERF_NR_CONTEXTS;
89
90 for_each_possible_cpu(cpu) {
91 entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
92 cpu_to_node(cpu));
93 if (!entries->cpu_entries[cpu])
94 goto fail;
95 }
96
97 rcu_assign_pointer(callchain_cpus_entries, entries);
98
99 return 0;
100
101fail:
102 for_each_possible_cpu(cpu)
103 kfree(entries->cpu_entries[cpu]);
104 kfree(entries);
105
106 return -ENOMEM;
107}
108
109int get_callchain_buffers(int event_max_stack)
110{
111 int err = 0;
112 int count;
113
114 mutex_lock(&callchain_mutex);
115
116 count = atomic_inc_return(&nr_callchain_events);
117 if (WARN_ON_ONCE(count < 1)) {
118 err = -EINVAL;
119 goto exit;
120 }
121
122 /*
123 * If requesting per event more than the global cap,
124 * return a different error to help userspace figure
125 * this out.
126 *
127 * And also do it here so that we have &callchain_mutex held.
128 */
129 if (event_max_stack > sysctl_perf_event_max_stack) {
130 err = -EOVERFLOW;
131 goto exit;
132 }
133
134 if (count == 1)
135 err = alloc_callchain_buffers();
136exit:
137 if (err)
138 atomic_dec(&nr_callchain_events);
139
140 mutex_unlock(&callchain_mutex);
141
142 return err;
143}
144
145void put_callchain_buffers(void)
146{
147 if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
148 release_callchain_buffers();
149 mutex_unlock(&callchain_mutex);
150 }
151}
152
153static struct perf_callchain_entry *get_callchain_entry(int *rctx)
154{
155 int cpu;
156 struct callchain_cpus_entries *entries;
157
158 *rctx = get_recursion_context(this_cpu_ptr(callchain_recursion));
159 if (*rctx == -1)
160 return NULL;
161
162 entries = rcu_dereference(callchain_cpus_entries);
163 if (!entries)
164 return NULL;
165
166 cpu = smp_processor_id();
167
168 return (((void *)entries->cpu_entries[cpu]) +
169 (*rctx * perf_callchain_entry__sizeof()));
170}
171
172static void
173put_callchain_entry(int rctx)
174{
175 put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
176}
177
178struct perf_callchain_entry *
179get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
180 u32 max_stack, bool crosstask, bool add_mark)
181{
182 struct perf_callchain_entry *entry;
183 struct perf_callchain_entry_ctx ctx;
184 int rctx;
185
186 entry = get_callchain_entry(&rctx);
187 if (rctx == -1)
188 return NULL;
189
190 if (!entry)
191 goto exit_put;
192
193 ctx.entry = entry;
194 ctx.max_stack = max_stack;
195 ctx.nr = entry->nr = init_nr;
196 ctx.contexts = 0;
197 ctx.contexts_maxed = false;
198
199 if (kernel && !user_mode(regs)) {
200 if (add_mark)
201 perf_callchain_store_context(&ctx, PERF_CONTEXT_KERNEL);
202 perf_callchain_kernel(&ctx, regs);
203 }
204
205 if (user) {
206 if (!user_mode(regs)) {
207 if (current->mm)
208 regs = task_pt_regs(current);
209 else
210 regs = NULL;
211 }
212
213 if (regs) {
214 mm_segment_t fs;
215
216 if (crosstask)
217 goto exit_put;
218
219 if (add_mark)
220 perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
221
222 fs = get_fs();
223 set_fs(USER_DS);
224 perf_callchain_user(&ctx, regs);
225 set_fs(fs);
226 }
227 }
228
229exit_put:
230 put_callchain_entry(rctx);
231
232 return entry;
233}
234
235/*
236 * Used for sysctl_perf_event_max_stack and
237 * sysctl_perf_event_max_contexts_per_stack.
238 */
239int perf_event_max_stack_handler(struct ctl_table *table, int write,
240 void __user *buffer, size_t *lenp, loff_t *ppos)
241{
242 int *value = table->data;
243 int new_value = *value, ret;
244 struct ctl_table new_table = *table;
245
246 new_table.data = &new_value;
247 ret = proc_dointvec_minmax(&new_table, write, buffer, lenp, ppos);
248 if (ret || !write)
249 return ret;
250
251 mutex_lock(&callchain_mutex);
252 if (atomic_read(&nr_callchain_events))
253 ret = -EBUSY;
254 else
255 *value = new_value;
256
257 mutex_unlock(&callchain_mutex);
258
259 return ret;
260}