fs/pstore/ftrace.c

   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 <linux/slab.h>
  20 #include <asm/barrier.h>
  21 #include "internal.h"
  22
  23 /* This doesn't need to be atomic: speed is chosen over correctness here. */
  24 static u64 pstore_ftrace_stamp;
  25
  26 static void notrace pstore_ftrace_call(unsigned long ip,
  27                                        unsigned long parent_ip,
  28                                        struct ftrace_ops *op,
  29                                        struct pt_regs *regs)
  30 {
  31         unsigned long flags;
  32         struct pstore_ftrace_record rec = {};
  33         struct pstore_record record = {
  34                 .type = PSTORE_TYPE_FTRACE,
  35                 .buf = (char *)&rec,
  36                 .size = sizeof(rec),
  37                 .psi = psinfo,
  38         };
  39
  40         if (unlikely(oops_in_progress))
  41                 return;
  42
  43         local_irq_save(flags);
  44
  45         rec.ip = ip;
  46         rec.parent_ip = parent_ip;
  47         pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
  48         pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
  49         psinfo->write(&record);
  50
  51         local_irq_restore(flags);
  52 }
  53
  54 static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
  55         .func   = pstore_ftrace_call,
  56 };
  57
  58 static DEFINE_MUTEX(pstore_ftrace_lock);
  59 static bool pstore_ftrace_enabled;
  60
  61 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
  62                                         size_t count, loff_t *ppos)
  63 {
  64         u8 on;
  65         ssize_t ret;
  66
  67         ret = kstrtou8_from_user(buf, count, 2, &on);
  68         if (ret)
  69                 return ret;
  70
  71         mutex_lock(&pstore_ftrace_lock);
  72
  73         if (!on ^ pstore_ftrace_enabled)
  74                 goto out;
  75
  76         if (on) {
  77                 ftrace_ops_set_global_filter(&pstore_ftrace_ops);
  78                 ret = register_ftrace_function(&pstore_ftrace_ops);
  79         } else {
  80                 ret = unregister_ftrace_function(&pstore_ftrace_ops);
  81         }
  82
  83         if (ret) {
  84                 pr_err("%s: unable to %sregister ftrace ops: %zd\n",
  85                        __func__, on ? "" : "un", ret);
  86                 goto err;
  87         }
  88
  89         pstore_ftrace_enabled = on;
  90 out:
  91         ret = count;
  92 err:
  93         mutex_unlock(&pstore_ftrace_lock);
  94
  95         return ret;
  96 }
  97
  98 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
  99                                        size_t count, loff_t *ppos)
 100 {
 101         char val[] = { '0' + pstore_ftrace_enabled, '\n' };
 102
 103         return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
 104 }
 105
 106 static const struct file_operations pstore_knob_fops = {
 107         .open   = simple_open,
 108         .read   = pstore_ftrace_knob_read,
 109         .write  = pstore_ftrace_knob_write,
 110 };
 111
 112 static struct dentry *pstore_ftrace_dir;
 113
 114 void pstore_register_ftrace(void)
 115 {
 116         if (!psinfo->write)
 117                 return;
 118
 119         pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
 120
 121         debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
 122                             &pstore_knob_fops);
 123 }
 124
 125 void pstore_unregister_ftrace(void)
 126 {
 127         mutex_lock(&pstore_ftrace_lock);
 128         if (pstore_ftrace_enabled) {
 129                 unregister_ftrace_function(&pstore_ftrace_ops);
 130                 pstore_ftrace_enabled = false;
 131         }
 132         mutex_unlock(&pstore_ftrace_lock);
 133
 134         debugfs_remove_recursive(pstore_ftrace_dir);
 135 }
 136
 137 ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
 138                                   const char *src_log, size_t src_log_size)
 139 {
 140         size_t dest_size, src_size, total, dest_off, src_off;
 141         size_t dest_idx = 0, src_idx = 0, merged_idx = 0;
 142         void *merged_buf;
 143         struct pstore_ftrace_record *drec, *srec, *mrec;
 144         size_t record_size = sizeof(struct pstore_ftrace_record);
 145
 146         dest_off = *dest_log_size % record_size;
 147         dest_size = *dest_log_size - dest_off;
 148
 149         src_off = src_log_size % record_size;
 150         src_size = src_log_size - src_off;
 151
 152         total = dest_size + src_size;
 153         merged_buf = kmalloc(total, GFP_KERNEL);
 154         if (!merged_buf)
 155                 return -ENOMEM;
 156
 157         drec = (struct pstore_ftrace_record *)(*dest_log + dest_off);
 158         srec = (struct pstore_ftrace_record *)(src_log + src_off);
 159         mrec = (struct pstore_ftrace_record *)(merged_buf);
 160
 161         while (dest_size > 0 && src_size > 0) {
 162                 if (pstore_ftrace_read_timestamp(&drec[dest_idx]) <
 163                     pstore_ftrace_read_timestamp(&srec[src_idx])) {
 164                         mrec[merged_idx++] = drec[dest_idx++];
 165                         dest_size -= record_size;
 166                 } else {
 167                         mrec[merged_idx++] = srec[src_idx++];
 168                         src_size -= record_size;
 169                 }
 170         }
 171
 172         while (dest_size > 0) {
 173                 mrec[merged_idx++] = drec[dest_idx++];
 174                 dest_size -= record_size;
 175         }
 176
 177         while (src_size > 0) {
 178                 mrec[merged_idx++] = srec[src_idx++];
 179                 src_size -= record_size;
 180         }
 181
 182         kfree(*dest_log);
 183         *dest_log = merged_buf;
 184         *dest_log_size = total;
 185
 186         return 0;
 187 }
 188 EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);