[PATCH] Kprobes: prevent possible race conditions generic

There are possible race conditions if probes are placed on routines within the
kprobes files and routines used by the kprobes.  For example if you put probe
on get_kprobe() routines, the system can hang while inserting probes on any
routine such as do_fork().  Because while inserting probes on do_fork(),
register_kprobes() routine grabs the kprobes spin lock and executes
get_kprobe() routine and to handle probe of get_kprobe(), kprobes_handler()
gets executed and tries to grab kprobes spin lock, and spins forever.  This
patch avoids such possible race conditions by preventing probes on routines
within the kprobes file and routines used by kprobes.

I have modified the patches as per Andi Kleen's suggestion to move kprobes
routines and other routines used by kprobes to a seperate section
.kprobes.text.

Also moved page fault and exception handlers, general protection fault to
.kprobes.text section.

These patches have been tested on i386, x86_64 and ppc64 architectures, also
compiled on ia64 and sparc64 architectures.

Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index e050fc2d4c26..e30afdca7917 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -42,6 +42,9 @@
 #define KPROBE_REENTER		0x00000004
 #define KPROBE_HIT_SSDONE	0x00000008
 
+/* Attach to insert probes on any functions which should be ignored*/
+#define __kprobes	__attribute__((__section__(".kprobes.text")))
+
 struct kprobe;
 struct pt_regs;
 struct kretprobe;