projects/linux·blob v7.1-rc2 · refs

230 lines · 5.6 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/profile.c
4 * Simple profiling. Manages a direct-mapped profile hit count buffer,
5 * with configurable resolution, support for restricting the cpus on
6 * which profiling is done, and switching between cpu time and
7 * schedule() calls via kernel command line parameters passed at boot.
8 *
9 * Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
10 * Red Hat, July 2004
11 * Consolidation of architecture support code for profiling,
12 * Nadia Yvette Chambers, Oracle, July 2004
13 * Amortized hit count accounting via per-cpu open-addressed hashtables
14 * to resolve timer interrupt livelocks, Nadia Yvette Chambers,
15 * Oracle, 2004
16 */
17
18#include <linux/export.h>
19#include <linux/profile.h>
20#include <linux/memblock.h>
21#include <linux/notifier.h>
22#include <linux/mm.h>
23#include <linux/cpumask.h>
24#include <linux/cpu.h>
25#include <linux/highmem.h>
26#include <linux/mutex.h>
27#include <linux/slab.h>
28#include <linux/vmalloc.h>
29#include <linux/sched/stat.h>
30
31#include <asm/sections.h>
32#include <asm/irq_regs.h>
33#include <asm/ptrace.h>
34
35struct profile_hit {
36 u32 pc, hits;
37};
38#define PROFILE_GRPSHIFT 3
39#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
40#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
41#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
42
43static atomic_t *prof_buffer;
44static unsigned long prof_len;
45static unsigned short int prof_shift;
46
47int prof_on __read_mostly;
48EXPORT_SYMBOL_GPL(prof_on);
49
50int profile_setup(char *str)
51{
52 static const char schedstr[] = "schedule";
53 static const char kvmstr[] = "kvm";
54 const char *select = NULL;
55 int par;
56
57 if (!strncmp(str, schedstr, strlen(schedstr))) {
58 prof_on = SCHED_PROFILING;
59 select = schedstr;
60 } else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
61 prof_on = KVM_PROFILING;
62 select = kvmstr;
63 } else if (get_option(&str, &par)) {
64 prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
65 prof_on = CPU_PROFILING;
66 pr_info("kernel profiling enabled (shift: %u)\n",
67 prof_shift);
68 }
69
70 if (select) {
71 if (str[strlen(select)] == ',')
72 str += strlen(select) + 1;
73 if (get_option(&str, &par))
74 prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
75 pr_info("kernel %s profiling enabled (shift: %u)\n",
76 select, prof_shift);
77 }
78
79 return 1;
80}
81__setup("profile=", profile_setup);
82
83
84int __ref profile_init(void)
85{
86 int buffer_bytes;
87 if (!prof_on)
88 return 0;
89
90 /* only text is profiled */
91 prof_len = (_etext - _stext) >> prof_shift;
92
93 if (!prof_len) {
94 pr_warn("profiling shift: %u too large\n", prof_shift);
95 prof_on = 0;
96 return -EINVAL;
97 }
98
99 buffer_bytes = prof_len*sizeof(atomic_t);
100
101 prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
102 if (prof_buffer)
103 return 0;
104
105 prof_buffer = alloc_pages_exact(buffer_bytes,
106 GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
107 if (prof_buffer)
108 return 0;
109
110 prof_buffer = vzalloc(buffer_bytes);
111 if (prof_buffer)
112 return 0;
113
114 return -ENOMEM;
115}
116
117static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
118{
119 unsigned long pc;
120 pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
121 if (pc < prof_len)
122 atomic_add(nr_hits, &prof_buffer[pc]);
123}
124
125void profile_hits(int type, void *__pc, unsigned int nr_hits)
126{
127 if (prof_on != type || !prof_buffer)
128 return;
129 do_profile_hits(type, __pc, nr_hits);
130}
131EXPORT_SYMBOL_GPL(profile_hits);
132
133void profile_tick(int type)
134{
135 struct pt_regs *regs = get_irq_regs();
136
137 /* This is the old kernel-only legacy profiling */
138 if (!user_mode(regs))
139 profile_hit(type, (void *)profile_pc(regs));
140}
141
142#ifdef CONFIG_PROC_FS
143#include <linux/proc_fs.h>
144#include <linux/seq_file.h>
145#include <linux/uaccess.h>
146
147/*
148 * This function accesses profiling information. The returned data is
149 * binary: the sampling step and the actual contents of the profile
150 * buffer. Use of the program readprofile is recommended in order to
151 * get meaningful info out of these data.
152 */
153static ssize_t
154read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
155{
156 unsigned long p = *ppos;
157 ssize_t read;
158 char *pnt;
159 unsigned long sample_step = 1UL << prof_shift;
160
161 if (p >= (prof_len+1)*sizeof(unsigned int))
162 return 0;
163 if (count > (prof_len+1)*sizeof(unsigned int) - p)
164 count = (prof_len+1)*sizeof(unsigned int) - p;
165 read = 0;
166
167 while (p < sizeof(unsigned int) && count > 0) {
168 if (put_user(*((char *)(&sample_step)+p), buf))
169 return -EFAULT;
170 buf++; p++; count--; read++;
171 }
172 pnt = (char *)prof_buffer + p - sizeof(atomic_t);
173 if (copy_to_user(buf, (void *)pnt, count))
174 return -EFAULT;
175 read += count;
176 *ppos += read;
177 return read;
178}
179
180/* default is to not implement this call */
181int __weak setup_profiling_timer(unsigned mult)
182{
183 return -EINVAL;
184}
185
186/*
187 * Writing to /proc/profile resets the counters
188 *
189 * Writing a 'profiling multiplier' value into it also re-sets the profiling
190 * interrupt frequency, on architectures that support this.
191 */
192static ssize_t write_profile(struct file *file, const char __user *buf,
193 size_t count, loff_t *ppos)
194{
195#ifdef CONFIG_SMP
196 if (count == sizeof(int)) {
197 unsigned int multiplier;
198
199 if (copy_from_user(&multiplier, buf, sizeof(int)))
200 return -EFAULT;
201
202 if (setup_profiling_timer(multiplier))
203 return -EINVAL;
204 }
205#endif
206 memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
207 return count;
208}
209
210static const struct proc_ops profile_proc_ops = {
211 .proc_read = read_profile,
212 .proc_write = write_profile,
213 .proc_lseek = default_llseek,
214};
215
216int __ref create_proc_profile(void)
217{
218 struct proc_dir_entry *entry;
219 int err = 0;
220
221 if (!prof_on)
222 return 0;
223 entry = proc_create("profile", S_IWUSR | S_IRUGO,
224 NULL, &profile_proc_ops);
225 if (entry)
226 proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
227 return err;
228}
229subsys_initcall(create_proc_profile);
230#endif /* CONFIG_PROC_FS */