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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2010-12-03 18:54:16 +0900
committerIngo Molnar <mingo@elte.hu>2010-12-06 17:59:31 +0100
commit0490cd1f9d99569d3bd64e17adc88db06a5007be (patch)
treea857099ce331773d5103f376860dd3f29f7a8b54 /kernel/kprobes.c
parent6274de4984a630b45c6934b3ee62e5692c745328 (diff)
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kprobes: Reuse unused kprobe
Reuse unused (waiting for unoptimizing and no user handler) kprobe on given address instead of returning -EBUSY for registering a new kprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: 2nddept-manager@sdl.hitachi.co.jp LKML-Reference: <20101203095416.2961.39080.stgit@ltc236.sdl.hitachi.co.jp> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r--kernel/kprobes.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index ba4d4c0740cf..134754d18bb4 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -692,6 +692,27 @@ static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
}
}
+/* Cancel unoptimizing for reusing */
+static void reuse_unused_kprobe(struct kprobe *ap)
+{
+ struct optimized_kprobe *op;
+
+ BUG_ON(!kprobe_unused(ap));
+ /*
+ * Unused kprobe MUST be on the way of delayed unoptimizing (means
+ * there is still a relative jump) and disabled.
+ */
+ op = container_of(ap, struct optimized_kprobe, kp);
+ if (unlikely(list_empty(&op->list)))
+ printk(KERN_WARNING "Warning: found a stray unused "
+ "aggrprobe@%p\n", ap->addr);
+ /* Enable the probe again */
+ ap->flags &= ~KPROBE_FLAG_DISABLED;
+ /* Optimize it again (remove from op->list) */
+ BUG_ON(!kprobe_optready(ap));
+ optimize_kprobe(ap);
+}
+
/* Remove optimized instructions */
static void __kprobes kill_optimized_kprobe(struct kprobe *p)
{
@@ -872,6 +893,13 @@ static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
#define kprobe_disarmed(p) kprobe_disabled(p)
#define wait_for_kprobe_optimizer() do {} while (0)
+/* There should be no unused kprobes can be reused without optimization */
+static void reuse_unused_kprobe(struct kprobe *ap)
+{
+ printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
+ BUG_ON(kprobe_unused(ap));
+}
+
static __kprobes void free_aggr_kprobe(struct kprobe *p)
{
arch_remove_kprobe(p);
@@ -1173,8 +1201,8 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
return -ENOMEM;
init_aggr_kprobe(ap, orig_p);
} else if (kprobe_unused(ap))
- /* Busy to die */
- return -EBUSY;
+ /* This probe is going to die. Rescue it */
+ reuse_unused_kprobe(ap);
if (kprobe_gone(ap)) {
/*