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 struct ftrace_ops *op, 33 struct pt_regs *regs) 34 { 35 unsigned long flags; 36 struct pstore_ftrace_record rec = {}; 37 38 if (unlikely(oops_in_progress)) 39 return; 40 41 local_irq_save(flags); 42 43 rec.ip = ip; 44 rec.parent_ip = parent_ip; 45 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id()); 46 psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec, 47 0, sizeof(rec), psinfo); 48 49 local_irq_restore(flags); 50 } 51 52 static struct ftrace_ops pstore_ftrace_ops __read_mostly = { 53 .func = pstore_ftrace_call, 54 }; 55 56 static DEFINE_MUTEX(pstore_ftrace_lock); 57 static bool pstore_ftrace_enabled; 58 59 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf, 60 size_t count, loff_t *ppos) 61 { 62 u8 on; 63 ssize_t ret; 64 65 ret = kstrtou8_from_user(buf, count, 2, &on); 66 if (ret) 67 return ret; 68 69 mutex_lock(&pstore_ftrace_lock); 70 71 if (!on ^ pstore_ftrace_enabled) 72 goto out; 73 74 if (on) 75 ret = register_ftrace_function(&pstore_ftrace_ops); 76 else 77 ret = unregister_ftrace_function(&pstore_ftrace_ops); 78 if (ret) { 79 pr_err("%s: unable to %sregister ftrace ops: %zd\n", 80 __func__, on ? "" : "un", ret); 81 goto err; 82 } 83 84 pstore_ftrace_enabled = on; 85 out: 86 ret = count; 87 err: 88 mutex_unlock(&pstore_ftrace_lock); 89 90 return ret; 91 } 92 93 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf, 94 size_t count, loff_t *ppos) 95 { 96 char val[] = { '0' + pstore_ftrace_enabled, '\n' }; 97 98 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val)); 99 } 100 101 static const struct file_operations pstore_knob_fops = { 102 .open = simple_open, 103 .read = pstore_ftrace_knob_read, 104 .write = pstore_ftrace_knob_write, 105 }; 106 107 void pstore_register_ftrace(void) 108 { 109 struct dentry *dir; 110 struct dentry *file; 111 112 if (!psinfo->write_buf) 113 return; 114 115 dir = debugfs_create_dir("pstore", NULL); 116 if (!dir) { 117 pr_err("%s: unable to create pstore directory\n", __func__); 118 return; 119 } 120 121 file = debugfs_create_file("record_ftrace", 0600, dir, NULL, 122 &pstore_knob_fops); 123 if (!file) { 124 pr_err("%s: unable to create record_ftrace file\n", __func__); 125 goto err_file; 126 } 127 128 return; 129 err_file: 130 debugfs_remove(dir); 131 } 132