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 35 struct 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 43 static atomic_t *prof_buffer; 44 static unsigned long prof_len; 45 static unsigned short int prof_shift; 46 47 int prof_on __read_mostly; 48 EXPORT_SYMBOL_GPL(prof_on); 49 50 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS) 51 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits); 52 static DEFINE_PER_CPU(int, cpu_profile_flip); 53 static DEFINE_MUTEX(profile_flip_mutex); 54 #endif /* CONFIG_SMP */ 55 56 int profile_setup(char *str) 57 { 58 static const char schedstr[] = "schedule"; 59 static const char sleepstr[] = "sleep"; 60 static const char kvmstr[] = "kvm"; 61 const char *select = NULL; 62 int par; 63 64 if (!strncmp(str, sleepstr, strlen(sleepstr))) { 65 #ifdef CONFIG_SCHEDSTATS 66 force_schedstat_enabled(); 67 prof_on = SLEEP_PROFILING; 68 select = sleepstr; 69 #else 70 pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n"); 71 #endif /* CONFIG_SCHEDSTATS */ 72 } else if (!strncmp(str, schedstr, strlen(schedstr))) { 73 prof_on = SCHED_PROFILING; 74 select = schedstr; 75 } else if (!strncmp(str, kvmstr, strlen(kvmstr))) { 76 prof_on = KVM_PROFILING; 77 select = kvmstr; 78 } else if (get_option(&str, &par)) { 79 prof_shift = clamp(par, 0, BITS_PER_LONG - 1); 80 prof_on = CPU_PROFILING; 81 pr_info("kernel profiling enabled (shift: %u)\n", 82 prof_shift); 83 } 84 85 if (select) { 86 if (str[strlen(select)] == ',') 87 str += strlen(select) + 1; 88 if (get_option(&str, &par)) 89 prof_shift = clamp(par, 0, BITS_PER_LONG - 1); 90 pr_info("kernel %s profiling enabled (shift: %u)\n", 91 select, prof_shift); 92 } 93 94 return 1; 95 } 96 __setup("profile=", profile_setup); 97 98 99 int __ref profile_init(void) 100 { 101 int buffer_bytes; 102 if (!prof_on) 103 return 0; 104 105 /* only text is profiled */ 106 prof_len = (_etext - _stext) >> prof_shift; 107 108 if (!prof_len) { 109 pr_warn("profiling shift: %u too large\n", prof_shift); 110 prof_on = 0; 111 return -EINVAL; 112 } 113 114 buffer_bytes = prof_len*sizeof(atomic_t); 115 116 prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN); 117 if (prof_buffer) 118 return 0; 119 120 prof_buffer = alloc_pages_exact(buffer_bytes, 121 GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN); 122 if (prof_buffer) 123 return 0; 124 125 prof_buffer = vzalloc(buffer_bytes); 126 if (prof_buffer) 127 return 0; 128 129 return -ENOMEM; 130 } 131 132 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits) 133 { 134 unsigned long pc; 135 pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift; 136 if (pc < prof_len) 137 atomic_add(nr_hits, &prof_buffer[pc]); 138 } 139 140 void profile_hits(int type, void *__pc, unsigned int nr_hits) 141 { 142 if (prof_on != type || !prof_buffer) 143 return; 144 do_profile_hits(type, __pc, nr_hits); 145 } 146 EXPORT_SYMBOL_GPL(profile_hits); 147 148 void profile_tick(int type) 149 { 150 struct pt_regs *regs = get_irq_regs(); 151 152 /* This is the old kernel-only legacy profiling */ 153 if (!user_mode(regs)) 154 profile_hit(type, (void *)profile_pc(regs)); 155 } 156 157 #ifdef CONFIG_PROC_FS 158 #include <linux/proc_fs.h> 159 #include <linux/seq_file.h> 160 #include <linux/uaccess.h> 161 162 /* 163 * This function accesses profiling information. The returned data is 164 * binary: the sampling step and the actual contents of the profile 165 * buffer. Use of the program readprofile is recommended in order to 166 * get meaningful info out of these data. 167 */ 168 static ssize_t 169 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos) 170 { 171 unsigned long p = *ppos; 172 ssize_t read; 173 char *pnt; 174 unsigned long sample_step = 1UL << prof_shift; 175 176 if (p >= (prof_len+1)*sizeof(unsigned int)) 177 return 0; 178 if (count > (prof_len+1)*sizeof(unsigned int) - p) 179 count = (prof_len+1)*sizeof(unsigned int) - p; 180 read = 0; 181 182 while (p < sizeof(unsigned int) && count > 0) { 183 if (put_user(*((char *)(&sample_step)+p), buf)) 184 return -EFAULT; 185 buf++; p++; count--; read++; 186 } 187 pnt = (char *)prof_buffer + p - sizeof(atomic_t); 188 if (copy_to_user(buf, (void *)pnt, count)) 189 return -EFAULT; 190 read += count; 191 *ppos += read; 192 return read; 193 } 194 195 /* default is to not implement this call */ 196 int __weak setup_profiling_timer(unsigned mult) 197 { 198 return -EINVAL; 199 } 200 201 /* 202 * Writing to /proc/profile resets the counters 203 * 204 * Writing a 'profiling multiplier' value into it also re-sets the profiling 205 * interrupt frequency, on architectures that support this. 206 */ 207 static ssize_t write_profile(struct file *file, const char __user *buf, 208 size_t count, loff_t *ppos) 209 { 210 #ifdef CONFIG_SMP 211 if (count == sizeof(int)) { 212 unsigned int multiplier; 213 214 if (copy_from_user(&multiplier, buf, sizeof(int))) 215 return -EFAULT; 216 217 if (setup_profiling_timer(multiplier)) 218 return -EINVAL; 219 } 220 #endif 221 memset(prof_buffer, 0, prof_len * sizeof(atomic_t)); 222 return count; 223 } 224 225 static const struct proc_ops profile_proc_ops = { 226 .proc_read = read_profile, 227 .proc_write = write_profile, 228 .proc_lseek = default_llseek, 229 }; 230 231 int __ref create_proc_profile(void) 232 { 233 struct proc_dir_entry *entry; 234 int err = 0; 235 236 if (!prof_on) 237 return 0; 238 entry = proc_create("profile", S_IWUSR | S_IRUGO, 239 NULL, &profile_proc_ops); 240 if (entry) 241 proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t)); 242 return err; 243 } 244 subsys_initcall(create_proc_profile); 245 #endif /* CONFIG_PROC_FS */ 246