include/wrapper/blkdev.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * wrapper/blkdev.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_BLKDEV_H
  13 #define _LTTNG_WRAPPER_BLKDEV_H
  14
  15 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0) \
  16         || LTTNG_RHEL_KERNEL_RANGE(5,14,0,162,0,0, 5,15,0,0,0,0))
  17 #include <linux/blkdev.h>
  18 #else
  19 #include <linux/genhd.h>
  20 #endif
  21
  22 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,17,0) \
  23         || LTTNG_RHEL_KERNEL_RANGE(5,14,0,162,0,0, 5,15,0,0,0,0))
  24 #define LTTNG_GENHD_FL_HIDDEN GENHD_FL_HIDDEN
  25 #else
  26 #define LTTNG_GENHD_FL_HIDDEN GENHD_FL_SUPPRESS_PARTITION_INFO
  27 #endif
  28
  29 #ifdef CONFIG_KALLSYMS_ALL
  30
  31 #include <linux/kallsyms.h>
  32 #include <wrapper/kallsyms.h>
  33
  34 static inline
  35 struct class *wrapper_get_block_class(void)
  36 {
  37         struct class *ptr_block_class;
  38
  39         ptr_block_class = (struct class *) kallsyms_lookup_dataptr("block_class");
  40         if (!ptr_block_class) {
  41                 printk_once(KERN_WARNING "LTTng: block_class symbol lookup failed.\n");
  42                 return NULL;
  43         }
  44         return ptr_block_class;
  45 }
  46
  47 /*
  48  * Canary function to check for 'block_class' at compile time.
  49  *
  50  * From 'include/linux/blkdev.h':
  51  *
  52  *   extern struct class block_class;
  53  */
  54 static inline
  55 struct class *__canary__get_block_class(void)
  56 {
  57         return &block_class;
  58 }
  59
  60 static inline
  61 struct device_type *wrapper_get_disk_type(void)
  62 {
  63         struct device_type *ptr_disk_type;
  64
  65         ptr_disk_type = (struct device_type *) kallsyms_lookup_dataptr("disk_type");
  66         if (!ptr_disk_type) {
  67                 printk_once(KERN_WARNING "LTTng: disk_type symbol lookup failed.\n");
  68                 return NULL;
  69         }
  70         return ptr_disk_type;
  71 }
  72
  73 /*
  74  * No canary for 'disk_type', it's only defined in 'block/genhd.c'.
  75  *
  76  * static inline
  77  * struct device_type *__canary__get_disk_type(void)
  78  * {
  79  *      return &disk_type;
  80  * }
  81  */
  82
  83 #else
  84
  85 static inline
  86 struct class *wrapper_get_block_class(void)
  87 {
  88         /*
  89          * Symbol block_class is not exported.
  90          * TODO: return &block_class;
  91          */
  92         /* Feature currently unavailable without KALLSYMS_ALL */
  93         return NULL;
  94 }
  95
  96 static inline
  97 struct device_type *wrapper_get_disk_type(void)
  98 {
  99         /*
 100          * Symbol disk_type is not exported.
 101          * TODO: return &disk_type;
 102          */
 103         /* Feature currently unavailable without KALLSYMS_ALL */
 104         return NULL;
 105 }
 106
 107 #endif
 108
 109 #endif /* _LTTNG_WRAPPER_BLKDEV_H */