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