Implement wrapper around get_pfnblock_flags_mask

[lttng-modules.git] / wrapper / page_alloc.c

diff --git a/wrapper/page_alloc.c b/wrapper/page_alloc.c
new file mode 100644 (file)
index 0000000..184ec71
--- /dev/null
+++ b/wrapper/page_alloc.c
@@ -0,0 +1,68 @@
+/*
+ * wrapper/page_alloc.c
+ *
+ * wrapper around get_pfnblock_flags_mask. Using KALLSYMS to get its address
+ * when available, else we need to have a kernel that exports this function to
+ * GPL modules.
+ *
+ * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "../lttng-kernel-version.h"
+
+#if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2))
+
+#include <linux/kallsyms.h>
+#include <linux/mm_types.h>
+#include <linux/module.h>
+#include "kallsyms.h"
+#include "page_alloc.h"
+
+static
+unsigned long (*get_pfnblock_flags_mask_sym)(struct page *page,
+               unsigned long pfn,
+               unsigned long end_bitidx,
+               unsigned long mask);
+
+unsigned long wrapper_get_pfnblock_flags_mask(struct page *page,
+               unsigned long pfn,
+               unsigned long end_bitidx,
+               unsigned long mask)
+{
+       WARN_ON_ONCE(!get_pfnblock_flags_mask_sym);
+       if (get_pfnblock_flags_mask_sym) {
+               return get_pfnblock_flags_mask_sym(page, pfn, end_bitidx, mask);
+       } else {
+               return -ENOSYS;
+       }
+}
+EXPORT_SYMBOL_GPL(wrapper_get_pfnblock_flags_mask);
+
+int wrapper_get_pfnblock_flags_mask_init(void)
+{
+       get_pfnblock_flags_mask_sym =
+               (void *) kallsyms_lookup_funcptr("get_pfnblock_flags_mask");
+       if (!get_pfnblock_flags_mask_sym)
+               return -1;
+       return 0;
+}
+
+#else /* #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
+
+#include <linux/pageblock-flags.h>
+
+#endif /* #else #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */