Kprobes: The ON/OFF knob thru debugfs

This patch provides a debugfs knob to turn kprobes on/off

o A new file /debug/kprobes/enabled indicates if kprobes is enabled or
  not (default enabled)
o Echoing 0 to this file will disarm all installed probes
o Any new probe registration when disabled will register the probe but
  not arm it. A message will be printed out in such a case.
o When a value 1 is echoed to the file, all probes (including ones
  registered in the intervening period) will be enabled
o Unregistration will happen irrespective of whether probes are globally
  enabled or not.
o Update Documentation/kprobes.txt to reflect these changes. While there
  also update the doc to make it current.

We are also looking at providing sysrq key support to tie to the disabling
feature provided by this patch.

[akpm@linux-foundation.org: Use bool like a bool!]
[akpm@linux-foundation.org: add printk facility levels]
[cornelia.huck@de.ibm.com: Add the missing arch_trampoline_kprobe() for s390]
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 6fc623e41fd8..23adf6075ae4 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -125,11 +125,16 @@ DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 #ifdef ARCH_SUPPORTS_KRETPROBES
 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
                                    struct pt_regs *regs);
+extern int arch_trampoline_kprobe(struct kprobe *p);
 #else /* ARCH_SUPPORTS_KRETPROBES */
 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
                                         struct pt_regs *regs)
 {
 }
+static inline int arch_trampoline_kprobe(struct kprobe *p)
+{
+        return 0;
+}
 #endif /* ARCH_SUPPORTS_KRETPROBES */
 /*
  * Function-return probe -