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 #ifdef CONFIG_KALLSYMS
  13
  14 #include <linux/kallsyms.h>
  15 #include <linux/mm_types.h>
  16 #include <linux/module.h>
  17 #include <wrapper/kallsyms.h>
  18 #include <wrapper/page_alloc.h>
  19
  20 static
  21 unsigned long (*get_pfnblock_flags_mask_sym)(struct page *page,
  22                 unsigned long pfn,
  23                 unsigned long end_bitidx,
  24                 unsigned long mask);
  25
  26 unsigned long wrapper_get_pfnblock_flags_mask(struct page *page,
  27                 unsigned long pfn,
  28                 unsigned long end_bitidx,
  29                 unsigned long mask)
  30 {
  31         WARN_ON_ONCE(!get_pfnblock_flags_mask_sym);
  32         if (get_pfnblock_flags_mask_sym) {
  33                 struct irq_ibt_state irq_ibt_state;
  34                 unsigned long ret;
  35
  36                 irq_ibt_state = wrapper_irq_ibt_save();
  37                 ret = get_pfnblock_flags_mask_sym(page, pfn, end_bitidx, mask);
  38                 wrapper_irq_ibt_restore(irq_ibt_state);
  39                 return ret;
  40         } else {
  41                 return -ENOSYS;
  42         }
  43 }
  44 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask);
  45
  46 int wrapper_get_pfnblock_flags_mask_init(void)
  47 {
  48         get_pfnblock_flags_mask_sym =
  49                 (void *) kallsyms_lookup_funcptr("get_pfnblock_flags_mask");
  50         if (!get_pfnblock_flags_mask_sym)
  51                 return -1;
  52         return 0;
  53 }
  54 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask_init);
  55
  56 /*
  57  * Canary function to check for 'get_pfnblock_flags_mask()' at compile time.
  58  *
  59  * From 'include/linux/pageblock-flags.h':
  60  *
  61  *   unsigned long get_pfnblock_flags_mask(struct page *page,
  62  *                                         unsigned long pfn,
  63  *                                         unsigned long end_bitidx,
  64  *                                         unsigned long mask);
  65  */
  66 __attribute__((unused)) static
  67 unsigned long __canary__get_pfnblock_flags_mask(struct page *page,
  68                                                 unsigned long pfn,
  69                                                 unsigned long end_bitidx,
  70                                                 unsigned long mask)
  71 {
  72         return get_pfnblock_flags_mask(page, pfn, end_bitidx, mask);
  73 }
  74
  75 #else
  76
  77 #include <linux/pageblock-flags.h>
  78
  79 #endif