wrapper/page_alloc.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  * wrapper/page_alloc.c
   3  *
   4  * wrapper around get_pfnblock_flags_mask and Ubuntu
   5  * get_pageblock_flags_mask. Using KALLSYMS to get their address when
   6  * available, else we need to have a kernel that exports this function
   7  * to GPL modules.
   8  *
   9  * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  */
  11
  12 #include <lttng-kernel-version.h>
  13
  14 #if (defined(CONFIG_KALLSYMS) \
  15         && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)        \
  16                 || LTTNG_KERNEL_RANGE(3,14,36, 3,15,0)          \
  17                 || LTTNG_KERNEL_RANGE(3,18,10, 3,19,0)          \
  18                 || LTTNG_DEBIAN_KERNEL_RANGE(3,16,7,9,0,0, 3,17,0,0,0,0) \
  19                 || LTTNG_UBUNTU_KERNEL_RANGE(3,16,7,34, 3,17,0,0)))
  20
  21 #include <linux/kallsyms.h>
  22 #include <linux/mm_types.h>
  23 #include <linux/module.h>
  24 #include <wrapper/kallsyms.h>
  25 #include <wrapper/page_alloc.h>
  26
  27 static
  28 unsigned long (*get_pfnblock_flags_mask_sym)(struct page *page,
  29                 unsigned long pfn,
  30                 unsigned long end_bitidx,
  31                 unsigned long mask);
  32
  33 unsigned long wrapper_get_pfnblock_flags_mask(struct page *page,
  34                 unsigned long pfn,
  35                 unsigned long end_bitidx,
  36                 unsigned long mask)
  37 {
  38         WARN_ON_ONCE(!get_pfnblock_flags_mask_sym);
  39         if (get_pfnblock_flags_mask_sym) {
  40                 return get_pfnblock_flags_mask_sym(page, pfn, end_bitidx, mask);
  41         } else {
  42                 return -ENOSYS;
  43         }
  44 }
  45 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask);
  46
  47 int wrapper_get_pfnblock_flags_mask_init(void)
  48 {
  49         get_pfnblock_flags_mask_sym =
  50                 (void *) kallsyms_lookup_funcptr("get_pfnblock_flags_mask");
  51         if (!get_pfnblock_flags_mask_sym)
  52                 return -1;
  53         return 0;
  54 }
  55 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask_init);
  56
  57 /*
  58  * Canary function to check for 'get_pfnblock_flags_mask()' at compile time.
  59  *
  60  * From 'include/linux/pageblock-flags.h':
  61  *
  62  *   unsigned long get_pfnblock_flags_mask(struct page *page,
  63  *                                         unsigned long pfn,
  64  *                                         unsigned long end_bitidx,
  65  *                                         unsigned long mask);
  66  */
  67 __attribute__((unused)) static
  68 unsigned long __canary__get_pfnblock_flags_mask(struct page *page,
  69                                                 unsigned long pfn,
  70                                                 unsigned long end_bitidx,
  71                                                 unsigned long mask)
  72 {
  73         return get_pfnblock_flags_mask(page, pfn, end_bitidx, mask);
  74 }
  75
  76 #else
  77
  78 #include <linux/pageblock-flags.h>
  79
  80 #endif
  81
  82 #if (defined(CONFIG_KALLSYMS) \
  83         && LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,50, 3,14,0,0))
  84
  85 #include <linux/kallsyms.h>
  86 #include <linux/mm_types.h>
  87 #include <linux/module.h>
  88 #include <wrapper/kallsyms.h>
  89 #include <wrapper/page_alloc.h>
  90
  91 static
  92 unsigned long (*get_pageblock_flags_mask_sym)(struct page *page,
  93                 unsigned long end_bitidx,
  94                 unsigned long mask);
  95
  96 unsigned long wrapper_get_pageblock_flags_mask(struct page *page,
  97                 unsigned long end_bitidx,
  98                 unsigned long mask)
  99 {
 100         WARN_ON_ONCE(!get_pageblock_flags_mask_sym);
 101         if (get_pageblock_flags_mask_sym) {
 102                 return get_pageblock_flags_mask_sym(page, end_bitidx, mask);
 103         } else {
 104                 return -ENOSYS;
 105         }
 106 }
 107 EXPORT_SYMBOL_GPL(wrapper_get_pageblock_flags_mask);
 108
 109 int wrapper_get_pageblock_flags_mask_init(void)
 110 {
 111         get_pageblock_flags_mask_sym =
 112                 (void *) kallsyms_lookup_funcptr("get_pageblock_flags_mask");
 113         if (!get_pageblock_flags_mask_sym)
 114                 return -1;
 115         return 0;
 116 }
 117 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask_init);
 118
 119 #else
 120
 121 #include <linux/pageblock-flags.h>
 122
 123 #endif