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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2009-03-06 10:35:52 -0500
committerIngo Molnar <mingo@elte.hu>2009-03-06 16:48:59 +0100
commit0e39ac444636ff5be39b26f1cb56d79594654dda (patch)
tree35ba33c22dc1d0a371570a6bd34a617a8cd68e8b /mm
parentf0ef03985130287c6c84ebe69416cf790e6cc00e (diff)
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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>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index baa999e87cd2..05fab3bc5b4b 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 @@ int randomize_va_space __read_mostly =
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;