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 static void notrace pstore_ftrace_call(unsigned long ip, 31 unsigned long parent_ip) 32 { 33 unsigned long flags; 34 struct pstore_ftrace_record rec = {}; 35 36 if (unlikely(oops_in_progress)) 37 return; 38 39 local_irq_save(flags); 40 41 rec.ip = ip; 42 rec.parent_ip = parent_ip; 43 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id()); 44 psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec, 45 sizeof(rec), psinfo); 46 47 local_irq_restore(flags); 48 } 49 50 static struct ftrace_ops pstore_ftrace_ops __read_mostly = { 51 .func = pstore_ftrace_call, 52 }; 53 54 static DEFINE_MUTEX(pstore_ftrace_lock); 55 static bool pstore_ftrace_enabled; 56 57 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf, 58 size_t count, loff_t *ppos) 59 { 60 u8 on; 61 ssize_t ret; 62 63 ret = kstrtou8_from_user(buf, count, 2, &on); 64 if (ret) 65 return ret; 66 67 mutex_lock(&pstore_ftrace_lock); 68 69 if (!on ^ pstore_ftrace_enabled) 70 goto out; 71 72 if (on) 73 ret = register_ftrace_function(&pstore_ftrace_ops); 74 else 75 ret = unregister_ftrace_function(&pstore_ftrace_ops); 76 if (ret) { 77 pr_err("%s: unable to %sregister ftrace ops: %zd\n", 78 __func__, on ? "" : "un", ret); 79 goto err; 80 } 81 82 pstore_ftrace_enabled = on; 83 out: 84 ret = count; 85 err: 86 mutex_unlock(&pstore_ftrace_lock); 87 88 return ret; 89 } 90 91 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf, 92 size_t count, loff_t *ppos) 93 { 94 char val[] = { '0' + pstore_ftrace_enabled, '\n' }; 95 96 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val)); 97 } 98 99 static const struct file_operations pstore_knob_fops = { 100 .open = simple_open, 101 .read = pstore_ftrace_knob_read, 102 .write = pstore_ftrace_knob_write, 103 }; 104 105 void pstore_register_ftrace(void) 106 { 107 struct dentry *dir; 108 struct dentry *file; 109 110 if (!psinfo->write_buf) 111 return; 112 113 dir = debugfs_create_dir("pstore", NULL); 114 if (!dir) { 115 pr_err("%s: unable to create pstore directory\n", __func__); 116 return; 117 } 118 119 file = debugfs_create_file("record_ftrace", 0600, dir, NULL, 120 &pstore_knob_fops); 121 if (!file) { 122 pr_err("%s: unable to create record_ftrace file\n", __func__); 123 goto err_file; 124 } 125 126 return; 127 err_file: 128 debugfs_remove(dir); 129 } 130