Merge tag 'for-5.18-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...
[platform/kernel/linux-starfive.git] / kernel / events / callchain.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Performance events callchain code, extracted from core.c:
4  *
5  *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
6  *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
7  *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
8  *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
9  */
10
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[];
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          * We can't use the percpu allocation API for data that can be
78          * accessed from NMI. Use a temporary manual per cpu allocation
79          * until that gets sorted out.
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         /*
122          * If requesting per event more than the global cap,
123          * return a different error to help userspace figure
124          * this out.
125          *
126          * And also do it here so that we have &callchain_mutex held.
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 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                 put_recursion_context(this_cpu_ptr(callchain_recursion), *rctx);
164                 return NULL;
165         }
166
167         cpu = smp_processor_id();
168
169         return (((void *)entries->cpu_entries[cpu]) +
170                 (*rctx * perf_callchain_entry__sizeof()));
171 }
172
173 void
174 put_callchain_entry(int rctx)
175 {
176         put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
177 }
178
179 struct perf_callchain_entry *
180 get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
181                    u32 max_stack, bool crosstask, bool add_mark)
182 {
183         struct perf_callchain_entry *entry;
184         struct perf_callchain_entry_ctx ctx;
185         int rctx;
186
187         entry = get_callchain_entry(&rctx);
188         if (!entry)
189                 return NULL;
190
191         ctx.entry     = entry;
192         ctx.max_stack = max_stack;
193         ctx.nr        = entry->nr = init_nr;
194         ctx.contexts       = 0;
195         ctx.contexts_maxed = false;
196
197         if (kernel && !user_mode(regs)) {
198                 if (add_mark)
199                         perf_callchain_store_context(&ctx, PERF_CONTEXT_KERNEL);
200                 perf_callchain_kernel(&ctx, regs);
201         }
202
203         if (user) {
204                 if (!user_mode(regs)) {
205                         if  (current->mm)
206                                 regs = task_pt_regs(current);
207                         else
208                                 regs = NULL;
209                 }
210
211                 if (regs) {
212                         if (crosstask)
213                                 goto exit_put;
214
215                         if (add_mark)
216                                 perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
217
218                         perf_callchain_user(&ctx, regs);
219                 }
220         }
221
222 exit_put:
223         put_callchain_entry(rctx);
224
225         return entry;
226 }
227
228 /*
229  * Used for sysctl_perf_event_max_stack and
230  * sysctl_perf_event_max_contexts_per_stack.
231  */
232 int perf_event_max_stack_handler(struct ctl_table *table, int write,
233                                  void *buffer, size_t *lenp, loff_t *ppos)
234 {
235         int *value = table->data;
236         int new_value = *value, ret;
237         struct ctl_table new_table = *table;
238
239         new_table.data = &new_value;
240         ret = proc_dointvec_minmax(&new_table, write, buffer, lenp, ppos);
241         if (ret || !write)
242                 return ret;
243
244         mutex_lock(&callchain_mutex);
245         if (atomic_read(&nr_callchain_events))
246                 ret = -EBUSY;
247         else
248                 *value = new_value;
249
250         mutex_unlock(&callchain_mutex);
251
252         return ret;
253 }