Fix: kmem probe with Ubuntu 3.13 kernels

Fixes an undefined reference to get_pageblock_flags_mask.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/wrapper/page_alloc.c b/wrapper/page_alloc.c
index 184ec71c221c0885b6753057c4571e8ee48b06f3..ceec7c0f831c9580e7d557befbde09028d894d51 100644 (file)
--- a/wrapper/page_alloc.c
+++ b/wrapper/page_alloc.c
@@ -1,9 +1,10 @@
 /*
  * 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.
+ * wrapper around get_pfnblock_flags_mask and Ubuntu
+ * get_pageblock_flags_mask. Using KALLSYMS to get their 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>
  *
@@ -61,8 +62,50 @@ int wrapper_get_pfnblock_flags_mask_init(void)
        return 0;
 }
 
-#else /* #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
+#else
 
 #include <linux/pageblock-flags.h>
 
-#endif /* #else #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
+#endif
+
+#if (defined(CONFIG_KALLSYMS) \
+       && LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,50, 3,14,0,0))
+
+#include <linux/kallsyms.h>
+#include <linux/mm_types.h>
+#include <linux/module.h>
+#include "kallsyms.h"
+#include "page_alloc.h"
+
+static
+unsigned long (*get_pageblock_flags_mask_sym)(struct page *page,
+               unsigned long end_bitidx,
+               unsigned long mask);
+
+unsigned long wrapper_get_pageblock_flags_mask(struct page *page,
+               unsigned long end_bitidx,
+               unsigned long mask)
+{
+       WARN_ON_ONCE(!get_pageblock_flags_mask_sym);
+       if (get_pageblock_flags_mask_sym) {
+               return get_pageblock_flags_mask_sym(page, end_bitidx, mask);
+       } else {
+               return -ENOSYS;
+       }
+}
+EXPORT_SYMBOL_GPL(wrapper_get_pageblock_flags_mask);
+
+int wrapper_get_pageblock_flags_mask_init(void)
+{
+       get_pageblock_flags_mask_sym =
+               (void *) kallsyms_lookup_funcptr("get_pageblock_flags_mask");
+       if (!get_pageblock_flags_mask_sym)
+               return -1;
+       return 0;
+}
+
+#else
+
+#include <linux/pageblock-flags.h>
+
+#endif

diff --git a/wrapper/page_alloc.h b/wrapper/page_alloc.h
index 06e2ddcb858c577fa8db63c02668e5962dd12393..f336fcb0f4dbaff5e9b2c4ebdbda719ea737da9b 100644 (file)
--- a/wrapper/page_alloc.h
+++ b/wrapper/page_alloc.h
@@ -39,7 +39,7 @@
 
 int wrapper_get_pfnblock_flags_mask_init(void);
 
-#else /* #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
+#else
 
 #include <linux/mm_types.h>
 
@@ -49,6 +49,38 @@ int wrapper_get_pfnblock_flags_mask_init(void)
        return 0;
 }
 
-#endif /* else #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
+#endif
+
+/*
+ * For a specific range of Ubuntu 3.13 kernels, we need to redefine
+ * get_pageblock_flags_mask to our wrapper, because the
+ * get_pageblock_migratetype() macro uses it. This function has been
+ * introduced into mainline within commit
+ * e58469bafd0524e848c3733bc3918d854595e20f, but never actually showed
+ * up in a stable kernel version, since it has been changed by commit
+ * dc4b0caff24d9b2918e9f27bc65499ee63187eba. Since Ubuntu chose to only
+ * backport the former commit but not the latter, we need to do a
+ * special case to cover this.
+ */
+#if (defined(CONFIG_KALLSYMS) \
+       && LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,50, 3,14,0,0))
+
+#define get_pageblock_flags_mask       wrapper_get_pageblock_flags_mask
+
+#include <linux/mm_types.h>
+
+int wrapper_get_pageblock_flags_mask_init(void);
+
+#else
+
+#include <linux/mm_types.h>
+
+static inline
+int wrapper_get_pageblock_flags_mask_init(void)
+{
+       return 0;
+}
+
+#endif
 
 #endif /* _LTTNG_WRAPPER_PAGE_ALLOC_H */