tracing, Text Edit Lock - Architecture Independent Code
This is an architecture independant synchronization around kernel text
modifications through use of a global mutex.
A mutex has been chosen so that kprobes, the main user of this, can sleep
during memory allocation between the memory read of the instructions it
must replace and the memory write of the breakpoint.
Other user of this interface: immediate values.
Paravirt and alternatives are always done when SMP is inactive, so there
is no need to use locks.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
LKML-Reference: <49B142D8.7020601@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/mm/memory.c b/mm/memory.c
index baa999e..05fab3b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -48,6 +48,8 @@
#include <linux/rmap.h>
#include <linux/module.h>
#include <linux/delayacct.h>
+#include <linux/kprobes.h>
+#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/writeback.h>
#include <linux/memcontrol.h>
@@ -99,6 +101,14 @@
2;
#endif
+/*
+ * mutex protecting text section modification (dynamic code patching).
+ * some users need to sleep (allocating memory...) while they hold this lock.
+ *
+ * NOT exported to modules - patching kernel text is a really delicate matter.
+ */
+DEFINE_MUTEX(text_mutex);
+
static int __init disable_randmaps(char *s)
{
randomize_va_space = 0;