wrapper/page_alloc.c

   1 /*
   2  * wrapper/page_alloc.c
   3  *
   4  * wrapper around get_pfnblock_flags_mask. Using KALLSYMS to get its address
   5  * when available, else we need to have a kernel that exports this function to
   6  * GPL modules.
   7  *
   8  * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * This library is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; only
  13  * version 2.1 of the License.
  14  *
  15  * This library is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with this library; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include "../lttng-kernel-version.h"
  26
  27 #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2))
  28
  29 #include <linux/kallsyms.h>
  30 #include <linux/mm_types.h>
  31 #include <linux/module.h>
  32 #include "kallsyms.h"
  33 #include "page_alloc.h"
  34
  35 static
  36 unsigned long (*get_pfnblock_flags_mask_sym)(struct page *page,
  37                 unsigned long pfn,
  38                 unsigned long end_bitidx,
  39                 unsigned long mask);
  40
  41 unsigned long wrapper_get_pfnblock_flags_mask(struct page *page,
  42                 unsigned long pfn,
  43                 unsigned long end_bitidx,
  44                 unsigned long mask)
  45 {
  46         WARN_ON_ONCE(!get_pfnblock_flags_mask_sym);
  47         if (get_pfnblock_flags_mask_sym) {
  48                 return get_pfnblock_flags_mask_sym(page, pfn, end_bitidx, mask);
  49         } else {
  50                 return -ENOSYS;
  51         }
  52 }
  53 EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask);
  54
  55 int wrapper_get_pfnblock_flags_mask_init(void)
  56 {
  57         get_pfnblock_flags_mask_sym =
  58                 (void *) kallsyms_lookup_funcptr("get_pfnblock_flags_mask");
  59         if (!get_pfnblock_flags_mask_sym)
  60                 return -1;
  61         return 0;
  62 }
  63
  64 #else /* #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
  65
  66 #include <linux/pageblock-flags.h>
  67
  68 #endif /* #else #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */