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