kprobes: makes kprobes/enabled works correctly for optimized kprobes.

debugfs/kprobes/enabled doesn't work correctly on optimized kprobes.
Masami Hiramatsu has a test report on x86_64 platform:

https://lkml.org/lkml/2015/1/19/274

This patch forces it to unoptimize kprobe if kprobes_all_disarmed is set.
It also checks the flag in unregistering path for skipping unneeded
disarming process when kprobes globally disarmed.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index c39790001854..c90e417bb963 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -869,7 +869,8 @@ static void __disarm_kprobe(struct kprobe *p, bool reopt)
 {
         struct kprobe *_p;
 
-        unoptimize_kprobe(p, false);    /* Try to unoptimize */
+        /* Try to unoptimize */
+        unoptimize_kprobe(p, kprobes_all_disarmed);
 
         if (!kprobe_queued(p)) {
                 arch_disarm_kprobe(p);
@@ -1571,7 +1572,13 @@ static struct kprobe *__disable_kprobe(struct kprobe *p)
 
                 /* Try to disarm and disable this/parent probe */
                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
-                        disarm_kprobe(orig_p, true);
+                        /*
+                         * If kprobes_all_disarmed is set, orig_p
+                         * should have already been disarmed, so
+                         * skip unneed disarming process.
+                         */
+                        if (!kprobes_all_disarmed)
+                                disarm_kprobe(orig_p, true);
                         orig_p->flags |= KPROBE_FLAG_DISABLED;
                 }
         }