Implement wrapper around get_pfnblock_flags_mask

This is used by kmem instrumentation, and changed in 4.0.0. This change
has been backported to 3.19.2 stable kernel.

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

diff --git a/Makefile b/Makefile
index 283cc46ae0d530d8d9340af80c2bf0385dd784b7..bdbd5b35b6cd6e2ad7c4042147cad002d5fa740a 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -36,6 +36,7 @@ lttng-tracer-objs :=  lttng-events.o lttng-abi.o \
                        lttng-context-vppid.o lttng-calibrate.o \
                        lttng-context-hostname.o wrapper/random.o \
                        probes/lttng.o wrapper/trace-clock.o \
+                       wrapper/page_alloc.o \
                        lttng-tracker-pid.o \
                        lttng-filter.o lttng-filter-interpreter.o \
                        lttng-filter-specialize.o \

diff --git a/lttng-events.c b/lttng-events.c
index 65bd0bf9ae6d45c4bbc0395d63211e9642330a59..053f125fa313a56d048fc5c0cd4c5ccff8e6526a 100644 (file)
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -20,6 +20,12 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/*
+ * This page_alloc.h wrapper needs to be included before gfpflags.h because it
+ * overrides a function with a define.
+ */
+#include "wrapper/page_alloc.h"
+
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/sched.h>
@@ -2115,7 +2121,9 @@ static int __init lttng_events_init(void)
        ret = wrapper_lttng_fixup_sig(THIS_MODULE);
        if (ret)
                return ret;
-
+       ret = wrapper_get_pfnblock_flags_mask_init();
+       if (ret)
+               return ret;
        ret = lttng_context_init();
        if (ret)
                return ret;

diff --git a/probes/lttng-probe-kmem.c b/probes/lttng-probe-kmem.c
index c8252ec0514de99be69e499601c916bbfdaf3b74..01202418dfc499884cb2b6f7bac510439c01d79d 100644 (file)
--- a/probes/lttng-probe-kmem.c
+++ b/probes/lttng-probe-kmem.c
@@ -21,6 +21,11 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/*
+ * This page_alloc.h wrapper needs to be included before gfpflags.h because it
+ * overrides a function with a define.
+ */
+#include "../wrapper/page_alloc.h"
 #include <linux/module.h>
 #include "../lttng-tracer.h"
 

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)) */

diff --git a/wrapper/page_alloc.h b/wrapper/page_alloc.h
new file mode 100644 (file)
index 0000000..06e2ddc
--- /dev/null
+++ b/wrapper/page_alloc.h
@@ -0,0 +1,54 @@
+#ifndef _LTTNG_WRAPPER_PAGE_ALLOC_H
+#define _LTTNG_WRAPPER_PAGE_ALLOC_H
+
+/*
+ * wrapper/page_alloc.h
+ *
+ * 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"
+
+/*
+ * We need to redefine get_pfnblock_flags_mask to our wrapper, because
+ * the get_pageblock_migratetype() macro uses it.
+ */
+#if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2))
+
+#define get_pfnblock_flags_mask                wrapper_get_pfnblock_flags_mask
+
+#include <linux/mm_types.h>
+
+int wrapper_get_pfnblock_flags_mask_init(void);
+
+#else /* #if defined(CONFIG_KALLSYMS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)) */
+
+#include <linux/mm_types.h>
+
+static inline
+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 /* _LTTNG_WRAPPER_PAGE_ALLOC_H */