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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>
This commit is contained in:
Masami Hiramatsu 2010-12-03 18:54:16 +09:00 committed by Ingo Molnar
parent 6274de4984
commit 0490cd1f9d
1 changed files with 30 additions and 2 deletions
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32
kernel/kprobes.c
View File

@ -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 */ /* Remove optimized instructions */
static void __kprobes kill_optimized_kprobe(struct kprobe *p) 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 kprobe_disarmed(p) kprobe_disabled(p)
#define wait_for_kprobe_optimizer() do {} while (0) #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) static __kprobes void free_aggr_kprobe(struct kprobe *p)
{ {
arch_remove_kprobe(p); arch_remove_kprobe(p);
@ -1173,8 +1201,8 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
return -ENOMEM; return -ENOMEM;
init_aggr_kprobe(ap, orig_p); init_aggr_kprobe(ap, orig_p);
} else if (kprobe_unused(ap)) } else if (kprobe_unused(ap))
/* Busy to die */ /* This probe is going to die. Rescue it */
return -EBUSY; reuse_unused_kprobe(ap);
if (kprobe_gone(ap)) { if (kprobe_gone(ap)) {
/* /*