pmsg.c 1.9 KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394
  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * Copyright 2014 Google, Inc.
  4. */
  5. #include <linux/cdev.h>
  6. #include <linux/device.h>
  7. #include <linux/fs.h>
  8. #include <linux/uaccess.h>
  9. #include "internal.h"
  10. static DEFINE_MUTEX(pmsg_lock);
  11. static ssize_t write_pmsg(struct file *file, const char __user *buf,
  12. size_t count, loff_t *ppos)
  13. {
  14. struct pstore_record record;
  15. int ret;
  16. if (!count)
  17. return 0;
  18. pstore_record_init(&record, psinfo);
  19. record.type = PSTORE_TYPE_PMSG;
  20. record.size = count;
  21. /* check outside lock, page in any data. write_user also checks */
  22. if (!access_ok(buf, count))
  23. return -EFAULT;
  24. mutex_lock(&pmsg_lock);
  25. ret = psinfo->write_user(&record, buf);
  26. mutex_unlock(&pmsg_lock);
  27. return ret ? ret : count;
  28. }
  29. static const struct file_operations pmsg_fops = {
  30. .owner = THIS_MODULE,
  31. .llseek = noop_llseek,
  32. .write = write_pmsg,
  33. };
  34. static struct class *pmsg_class;
  35. static int pmsg_major;
  36. #define PMSG_NAME "pmsg"
  37. #undef pr_fmt
  38. #define pr_fmt(fmt) PMSG_NAME ": " fmt
  39. static char *pmsg_devnode(struct device *dev, umode_t *mode)
  40. {
  41. if (mode)
  42. *mode = 0220;
  43. return NULL;
  44. }
  45. void pstore_register_pmsg(void)
  46. {
  47. struct device *pmsg_device;
  48. pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);
  49. if (pmsg_major < 0) {
  50. pr_err("register_chrdev failed\n");
  51. goto err;
  52. }
  53. pmsg_class = class_create(THIS_MODULE, PMSG_NAME);
  54. if (IS_ERR(pmsg_class)) {
  55. pr_err("device class file already in use\n");
  56. goto err_class;
  57. }
  58. pmsg_class->devnode = pmsg_devnode;
  59. pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0),
  60. NULL, "%s%d", PMSG_NAME, 0);
  61. if (IS_ERR(pmsg_device)) {
  62. pr_err("failed to create device\n");
  63. goto err_device;
  64. }
  65. return;
  66. err_device:
  67. class_destroy(pmsg_class);
  68. err_class:
  69. unregister_chrdev(pmsg_major, PMSG_NAME);
  70. err:
  71. return;
  72. }
  73. void pstore_unregister_pmsg(void)
  74. {
  75. device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
  76. class_destroy(pmsg_class);
  77. unregister_chrdev(pmsg_major, PMSG_NAME);
  78. }