1 /* 2 * Copyright 2012 Google, Inc. 3 * 4 * This software is licensed under the terms of the GNU General Public 5 * License version 2, as published by the Free Software Foundation, and 6 * may be copied, distributed, and modified under those terms. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/compiler.h> 16 #include <linux/irqflags.h> 17 #include <linux/percpu.h> 18 #include <linux/smp.h> 19 #include <linux/atomic.h> 20 #include <linux/types.h> 21 #include <linux/mutex.h> 22 #include <linux/ftrace.h> 23 #include <linux/fs.h> 24 #include <linux/debugfs.h> 25 #include <linux/err.h> 26 #include <linux/cache.h> 27 #include <asm/barrier.h> 28 #include "internal.h" 29 30 /* This doesn't need to be atomic: speed is chosen over correctness here. */ 31 static u64 pstore_ftrace_stamp; 32 33 static void notrace pstore_ftrace_call(unsigned long ip, 34 unsigned long parent_ip, 35 struct ftrace_ops *op, 36 struct pt_regs *regs) 37 { 38 unsigned long flags; 39 struct pstore_ftrace_record rec = {}; 40 41 if (unlikely(oops_in_progress)) 42 return; 43 44 local_irq_save(flags); 45 46 rec.ip = ip; 47 rec.parent_ip = parent_ip; 48 pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++); 49 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id()); 50 psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec, 51 0, sizeof(rec), psinfo); 52 53 local_irq_restore(flags); 54 } 55 56 static struct ftrace_ops pstore_ftrace_ops __read_mostly = { 57 .func = pstore_ftrace_call, 58 }; 59 60 static DEFINE_MUTEX(pstore_ftrace_lock); 61 static bool pstore_ftrace_enabled; 62 63 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf, 64 size_t count, loff_t *ppos) 65 { 66 u8 on; 67 ssize_t ret; 68 69 ret = kstrtou8_from_user(buf, count, 2, &on); 70 if (ret) 71 return ret; 72 73 mutex_lock(&pstore_ftrace_lock); 74 75 if (!on ^ pstore_ftrace_enabled) 76 goto out; 77 78 if (on) { 79 ftrace_ops_set_global_filter(&pstore_ftrace_ops); 80 ret = register_ftrace_function(&pstore_ftrace_ops); 81 } else { 82 ret = unregister_ftrace_function(&pstore_ftrace_ops); 83 } 84 85 if (ret) { 86 pr_err("%s: unable to %sregister ftrace ops: %zd\n", 87 __func__, on ? "" : "un", ret); 88 goto err; 89 } 90 91 pstore_ftrace_enabled = on; 92 out: 93 ret = count; 94 err: 95 mutex_unlock(&pstore_ftrace_lock); 96 97 return ret; 98 } 99 100 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf, 101 size_t count, loff_t *ppos) 102 { 103 char val[] = { '0' + pstore_ftrace_enabled, '\n' }; 104 105 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val)); 106 } 107 108 static const struct file_operations pstore_knob_fops = { 109 .open = simple_open, 110 .read = pstore_ftrace_knob_read, 111 .write = pstore_ftrace_knob_write, 112 }; 113 114 static struct dentry *pstore_ftrace_dir; 115 116 void pstore_register_ftrace(void) 117 { 118 struct dentry *file; 119 120 if (!psinfo->write_buf) 121 return; 122 123 pstore_ftrace_dir = debugfs_create_dir("pstore", NULL); 124 if (!pstore_ftrace_dir) { 125 pr_err("%s: unable to create pstore directory\n", __func__); 126 return; 127 } 128 129 file = debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, 130 NULL, &pstore_knob_fops); 131 if (!file) { 132 pr_err("%s: unable to create record_ftrace file\n", __func__); 133 goto err_file; 134 } 135 136 return; 137 err_file: 138 debugfs_remove(pstore_ftrace_dir); 139 } 140 141 void pstore_unregister_ftrace(void) 142 { 143 mutex_lock(&pstore_ftrace_lock); 144 if (pstore_ftrace_enabled) { 145 unregister_ftrace_function(&pstore_ftrace_ops); 146 pstore_ftrace_enabled = 0; 147 } 148 mutex_unlock(&pstore_ftrace_lock); 149 150 debugfs_remove_recursive(pstore_ftrace_dir); 151 } 152