mtd: Use kasprintf() instead of fixed buffer formatting
[linux/fpc-iii.git] / kernel / events / callchain.c
blobc187aa3df3c8b789c23cceaf5214bc033fa3e2c9
1 /*
2 * Performance events callchain code, extracted from core.c:
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>
9 * For licensing details see kernel-base/COPYING
12 #include <linux/perf_event.h>
13 #include <linux/slab.h>
14 #include <linux/sched/task_stack.h>
16 #include "internal.h"
18 struct callchain_cpus_entries {
19 struct rcu_head rcu_head;
20 struct perf_callchain_entry *cpu_entries[0];
23 int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
24 int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK;
26 static inline size_t perf_callchain_entry__sizeof(void)
28 return (sizeof(struct perf_callchain_entry) +
29 sizeof(__u64) * (sysctl_perf_event_max_stack +
30 sysctl_perf_event_max_contexts_per_stack));
33 static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
34 static atomic_t nr_callchain_events;
35 static DEFINE_MUTEX(callchain_mutex);
36 static struct callchain_cpus_entries *callchain_cpus_entries;
39 __weak void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
40 struct pt_regs *regs)
44 __weak void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
45 struct pt_regs *regs)
49 static void release_callchain_buffers_rcu(struct rcu_head *head)
51 struct callchain_cpus_entries *entries;
52 int cpu;
54 entries = container_of(head, struct callchain_cpus_entries, rcu_head);
56 for_each_possible_cpu(cpu)
57 kfree(entries->cpu_entries[cpu]);
59 kfree(entries);
62 static void release_callchain_buffers(void)
64 struct callchain_cpus_entries *entries;
66 entries = callchain_cpus_entries;
67 RCU_INIT_POINTER(callchain_cpus_entries, NULL);
68 call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
71 static int alloc_callchain_buffers(void)
73 int cpu;
74 int size;
75 struct callchain_cpus_entries *entries;
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.
82 size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
84 entries = kzalloc(size, GFP_KERNEL);
85 if (!entries)
86 return -ENOMEM;
88 size = perf_callchain_entry__sizeof() * PERF_NR_CONTEXTS;
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;
97 rcu_assign_pointer(callchain_cpus_entries, entries);
99 return 0;
101 fail:
102 for_each_possible_cpu(cpu)
103 kfree(entries->cpu_entries[cpu]);
104 kfree(entries);
106 return -ENOMEM;
109 int get_callchain_buffers(int event_max_stack)
111 int err = 0;
112 int count;
114 mutex_lock(&callchain_mutex);
116 count = atomic_inc_return(&nr_callchain_events);
117 if (WARN_ON_ONCE(count < 1)) {
118 err = -EINVAL;
119 goto exit;
123 * If requesting per event more than the global cap,
124 * return a different error to help userspace figure
125 * this out.
127 * And also do it here so that we have &callchain_mutex held.
129 if (event_max_stack > sysctl_perf_event_max_stack) {
130 err = -EOVERFLOW;
131 goto exit;
134 if (count == 1)
135 err = alloc_callchain_buffers();
136 exit:
137 if (err)
138 atomic_dec(&nr_callchain_events);
140 mutex_unlock(&callchain_mutex);
142 return err;
145 void put_callchain_buffers(void)
147 if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
148 release_callchain_buffers();
149 mutex_unlock(&callchain_mutex);
153 static struct perf_callchain_entry *get_callchain_entry(int *rctx)
155 int cpu;
156 struct callchain_cpus_entries *entries;
158 *rctx = get_recursion_context(this_cpu_ptr(callchain_recursion));
159 if (*rctx == -1)
160 return NULL;
162 entries = rcu_dereference(callchain_cpus_entries);
163 if (!entries)
164 return NULL;
166 cpu = smp_processor_id();
168 return (((void *)entries->cpu_entries[cpu]) +
169 (*rctx * perf_callchain_entry__sizeof()));
172 static void
173 put_callchain_entry(int rctx)
175 put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
178 struct perf_callchain_entry *
179 get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
180 u32 max_stack, bool crosstask, bool add_mark)
182 struct perf_callchain_entry *entry;
183 struct perf_callchain_entry_ctx ctx;
184 int rctx;
186 entry = get_callchain_entry(&rctx);
187 if (rctx == -1)
188 return NULL;
190 if (!entry)
191 goto exit_put;
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;
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);
205 if (user) {
206 if (!user_mode(regs)) {
207 if (current->mm)
208 regs = task_pt_regs(current);
209 else
210 regs = NULL;
213 if (regs) {
214 mm_segment_t fs;
216 if (crosstask)
217 goto exit_put;
219 if (add_mark)
220 perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
222 fs = get_fs();
223 set_fs(USER_DS);
224 perf_callchain_user(&ctx, regs);
225 set_fs(fs);
229 exit_put:
230 put_callchain_entry(rctx);
232 return entry;
236 * Used for sysctl_perf_event_max_stack and
237 * sysctl_perf_event_max_contexts_per_stack.
239 int perf_event_max_stack_handler(struct ctl_table *table, int write,
240 void __user *buffer, size_t *lenp, loff_t *ppos)
242 int *value = table->data;
243 int new_value = *value, ret;
244 struct ctl_table new_table = *table;
246 new_table.data = &new_value;
247 ret = proc_dointvec_minmax(&new_table, write, buffer, lenp, ppos);
248 if (ret || !write)
249 return ret;
251 mutex_lock(&callchain_mutex);
252 if (atomic_read(&nr_callchain_events))
253 ret = -EBUSY;
254 else
255 *value = new_value;
257 mutex_unlock(&callchain_mutex);
259 return ret;