1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright 2012 Google, Inc. 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/compiler.h> 8 #include <linux/irqflags.h> 9 #include <linux/percpu.h> 10 #include <linux/smp.h> 11 #include <linux/atomic.h> 12 #include <linux/types.h> 13 #include <linux/mutex.h> 14 #include <linux/ftrace.h> 15 #include <linux/fs.h> 16 #include <linux/debugfs.h> 17 #include <linux/err.h> 18 #include <linux/cache.h> 19 #include <asm/barrier.h> 20 #include "internal.h" 21 22 /* This doesn't need to be atomic: speed is chosen over correctness here. */ 23 static u64 pstore_ftrace_stamp; 24 25 static void notrace pstore_ftrace_call(unsigned long ip, 26 unsigned long parent_ip, 27 struct ftrace_ops *op, 28 struct pt_regs *regs) 29 { 30 unsigned long flags; 31 struct pstore_ftrace_record rec = {}; 32 struct pstore_record record = { 33 .type = PSTORE_TYPE_FTRACE, 34 .buf = (char *)&rec, 35 .size = sizeof(rec), 36 .psi = psinfo, 37 }; 38 39 if (unlikely(oops_in_progress)) 40 return; 41 42 local_irq_save(flags); 43 44 rec.ip = ip; 45 rec.parent_ip = parent_ip; 46 pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++); 47 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id()); 48 psinfo->write(&record); 49 50 local_irq_restore(flags); 51 } 52 53 static struct ftrace_ops pstore_ftrace_ops __read_mostly = { 54 .func = pstore_ftrace_call, 55 }; 56 57 static DEFINE_MUTEX(pstore_ftrace_lock); 58 static bool pstore_ftrace_enabled; 59 60 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf, 61 size_t count, loff_t *ppos) 62 { 63 u8 on; 64 ssize_t ret; 65 66 ret = kstrtou8_from_user(buf, count, 2, &on); 67 if (ret) 68 return ret; 69 70 mutex_lock(&pstore_ftrace_lock); 71 72 if (!on ^ pstore_ftrace_enabled) 73 goto out; 74 75 if (on) { 76 ftrace_ops_set_global_filter(&pstore_ftrace_ops); 77 ret = register_ftrace_function(&pstore_ftrace_ops); 78 } else { 79 ret = unregister_ftrace_function(&pstore_ftrace_ops); 80 } 81 82 if (ret) { 83 pr_err("%s: unable to %sregister ftrace ops: %zd\n", 84 __func__, on ? "" : "un", ret); 85 goto err; 86 } 87 88 pstore_ftrace_enabled = on; 89 out: 90 ret = count; 91 err: 92 mutex_unlock(&pstore_ftrace_lock); 93 94 return ret; 95 } 96 97 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf, 98 size_t count, loff_t *ppos) 99 { 100 char val[] = { '0' + pstore_ftrace_enabled, '\n' }; 101 102 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val)); 103 } 104 105 static const struct file_operations pstore_knob_fops = { 106 .open = simple_open, 107 .read = pstore_ftrace_knob_read, 108 .write = pstore_ftrace_knob_write, 109 }; 110 111 static struct dentry *pstore_ftrace_dir; 112 113 void pstore_register_ftrace(void) 114 { 115 if (!psinfo->write) 116 return; 117 118 pstore_ftrace_dir = debugfs_create_dir("pstore", NULL); 119 120 debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL, 121 &pstore_knob_fops); 122 } 123 124 void pstore_unregister_ftrace(void) 125 { 126 mutex_lock(&pstore_ftrace_lock); 127 if (pstore_ftrace_enabled) { 128 unregister_ftrace_function(&pstore_ftrace_ops); 129 pstore_ftrace_enabled = false; 130 } 131 mutex_unlock(&pstore_ftrace_lock); 132 133 debugfs_remove_recursive(pstore_ftrace_dir); 134 } 135