src/wrapper/page_alloc.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   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         && (LTTNG_LINUX_VERSION_CODE >= LTTNG_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                 struct irq_ibt_state irq_ibt_state;
  41                 unsigned long ret;
  42
  43                 irq_ibt_state = wrapper_irq_ibt_save();
  44                 ret = get_pfnblock_flags_mask_sym(page, pfn, end_bitidx, mask);
  45                 wrapper_irq_ibt_restore(irq_ibt_state);
  46                 return ret;
  47         } else {
  48                 return -ENOSYS;
  49         }
  50 }
  51 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask);
  52
  53 int wrapper_get_pfnblock_flags_mask_init(void)
  54 {
  55         get_pfnblock_flags_mask_sym =
  56                 (void *) kallsyms_lookup_funcptr("get_pfnblock_flags_mask");
  57         if (!get_pfnblock_flags_mask_sym)
  58                 return -1;
  59         return 0;
  60 }
  61 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask_init);
  62
  63 /*
  64  * Canary function to check for 'get_pfnblock_flags_mask()' at compile time.
  65  *
  66  * From 'include/linux/pageblock-flags.h':
  67  *
  68  *   unsigned long get_pfnblock_flags_mask(struct page *page,
  69  *                                         unsigned long pfn,
  70  *                                         unsigned long end_bitidx,
  71  *                                         unsigned long mask);
  72  */
  73 __attribute__((unused)) static
  74 unsigned long __canary__get_pfnblock_flags_mask(struct page *page,
  75                                                 unsigned long pfn,
  76                                                 unsigned long end_bitidx,
  77                                                 unsigned long mask)
  78 {
  79         return get_pfnblock_flags_mask(page, pfn, end_bitidx, mask);
  80 }
  81
  82 #else
  83
  84 #include <linux/pageblock-flags.h>
  85
  86 #endif
  87
  88 #if (defined(CONFIG_KALLSYMS) \
  89         && LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,50, 3,14,0,0))
  90
  91 #include <linux/kallsyms.h>
  92 #include <linux/mm_types.h>
  93 #include <linux/module.h>
  94 #include <wrapper/kallsyms.h>
  95 #include <wrapper/page_alloc.h>
  96
  97 static
  98 unsigned long (*get_pageblock_flags_mask_sym)(struct page *page,
  99                 unsigned long end_bitidx,
 100                 unsigned long mask);
 101
 102 unsigned long wrapper_get_pageblock_flags_mask(struct page *page,
 103                 unsigned long end_bitidx,
 104                 unsigned long mask)
 105 {
 106         WARN_ON_ONCE(!get_pageblock_flags_mask_sym);
 107         if (get_pageblock_flags_mask_sym) {
 108                 return get_pageblock_flags_mask_sym(page, end_bitidx, mask);
 109         } else {
 110                 return -ENOSYS;
 111         }
 112 }
 113 EXPORT_SYMBOL_GPL(wrapper_get_pageblock_flags_mask);
 114
 115 int wrapper_get_pageblock_flags_mask_init(void)
 116 {
 117         get_pageblock_flags_mask_sym =
 118                 (void *) kallsyms_lookup_funcptr("get_pageblock_flags_mask");
 119         if (!get_pageblock_flags_mask_sym)
 120                 return -1;
 121         return 0;
 122 }
 123 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask_init);
 124
 125 #else
 126
 127 #include <linux/pageblock-flags.h>
 128
 129 #endif