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 int 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 84 int __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 } 116 117 static 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 } 124 125 void 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 } 131 EXPORT_SYMBOL_GPL(profile_hits); 132 133 void 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 */ 153 static ssize_t 154 read_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 */ 181 int __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 */ 192 static 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 } 209 210 static const struct proc_ops profile_proc_ops = { 211 .proc_read = read_profile, 212 .proc_write = write_profile, 213 .proc_lseek = default_llseek, 214 }; 215 216 int __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 } 229 subsys_initcall(create_proc_profile); 230 #endif /* CONFIG_PROC_FS */ 231