include/wrapper/genhd.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * wrapper/genhd.h
   4  *
   5  * wrapper around block layer functions and data structures. Using
   6  * KALLSYMS to get its address when available, else we need to have a
   7  * kernel that exports this function to GPL modules.
   8  *
   9  * Copyright (C) 2011-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  */
  11
  12 #ifndef _LTTNG_WRAPPER_GENHD_H
  13 #define _LTTNG_WRAPPER_GENHD_H
  14
  15 #include <linux/genhd.h>
  16 #include <lttng/kernel-version.h>
  17
  18 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,11,0))
  19 #define LTTNG_DISK_PART_TYPE struct block_device
  20 #else
  21 #define LTTNG_DISK_PART_TYPE struct hd_struct
  22 #endif
  23
  24 #ifdef CONFIG_KALLSYMS_ALL
  25
  26 #include <linux/kallsyms.h>
  27 #include <wrapper/kallsyms.h>
  28
  29 static inline
  30 struct class *wrapper_get_block_class(void)
  31 {
  32         struct class *ptr_block_class;
  33
  34         ptr_block_class = (struct class *) kallsyms_lookup_dataptr("block_class");
  35         if (!ptr_block_class) {
  36                 printk_once(KERN_WARNING "LTTng: block_class symbol lookup failed.\n");
  37                 return NULL;
  38         }
  39         return ptr_block_class;
  40 }
  41
  42 /*
  43  * Canary function to check for 'block_class' at compile time.
  44  *
  45  * From 'include/linux/genhd.h':
  46  *
  47  *   extern struct class block_class;
  48  */
  49 static inline
  50 struct class *__canary__get_block_class(void)
  51 {
  52         return &block_class;
  53 }
  54
  55 static inline
  56 struct device_type *wrapper_get_disk_type(void)
  57 {
  58         struct device_type *ptr_disk_type;
  59
  60         ptr_disk_type = (struct device_type *) kallsyms_lookup_dataptr("disk_type");
  61         if (!ptr_disk_type) {
  62                 printk_once(KERN_WARNING "LTTng: disk_type symbol lookup failed.\n");
  63                 return NULL;
  64         }
  65         return ptr_disk_type;
  66 }
  67
  68 /*
  69  * No canary for 'disk_type', it's only defined in 'block/genhd.c'.
  70  *
  71  * static inline
  72  * struct device_type *__canary__get_disk_type(void)
  73  * {
  74  *      return &disk_type;
  75  * }
  76  */
  77
  78 #else
  79
  80 static inline
  81 struct class *wrapper_get_block_class(void)
  82 {
  83         /*
  84          * Symbol block_class is not exported.
  85          * TODO: return &block_class;
  86          */
  87         /* Feature currently unavailable without KALLSYMS_ALL */
  88         return NULL;
  89 }
  90
  91 static inline
  92 struct device_type *wrapper_get_disk_type(void)
  93 {
  94         /*
  95          * Symbol disk_type is not exported.
  96          * TODO: return &disk_type;
  97          */
  98         /* Feature currently unavailable without KALLSYMS_ALL */
  99         return NULL;
 100 }
 101
 102 #endif
 103
 104 /*
 105  * This wrapper has an 'int' return type instead of the original 'void', to be
 106  * able to report the symbol lookup failure to the caller.
 107  *
 108  * Return 0 on success, -1 on error.
 109  */
 110 int wrapper_disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 111                           unsigned int flags);
 112 LTTNG_DISK_PART_TYPE *wrapper_disk_part_iter_next(struct disk_part_iter *piter);
 113 void wrapper_disk_part_iter_exit(struct disk_part_iter *piter);
 114
 115 /*
 116  * Canary function to check for 'disk_part_iter_init()' at compile time.
 117  *
 118  * From 'include/linux/genhd.h':
 119  *
 120  *   extern void disk_part_iter_init(struct disk_part_iter *piter,
 121  *                                   struct gendisk *disk, unsigned int flags);
 122  *
 123  */
 124 static inline
 125 void __canary__disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 126                 unsigned int flags)
 127 {
 128         disk_part_iter_init(piter, disk, flags);
 129 }
 130
 131 /*
 132  * Canary function to check for 'disk_part_iter_next()' at compile time.
 133  *
 134  * From 'include/linux/genhd.h':
 135  *
 136  *   struct block_device *disk_part_iter_next(struct disk_part_iter *piter);
 137  *
 138  */
 139 static inline
 140 LTTNG_DISK_PART_TYPE *__canary__disk_part_iter_next(struct disk_part_iter *piter)
 141 {
 142         return disk_part_iter_next(piter);
 143 }
 144
 145 /*
 146  * Canary function to check for 'disk_part_iter_exit()' at compile time.
 147  *
 148  * From 'include/linux/genhd.h':
 149  *
 150  *   extern void disk_part_iter_exit(struct disk_part_iter *piter);
 151  *
 152  */
 153 static inline
 154 void __canary__disk_part_iter_exit(struct disk_part_iter *piter)
 155 {
 156         return disk_part_iter_exit(piter);
 157 }
 158
 159 #endif /* _LTTNG_WRAPPER_GENHD_H */