[PATCH] Kprobe: multi kprobe posthandler for booster

If there are multi kprobes on the same probepoint, there will be one extra
aggr_kprobe on the head of kprobe list.  The aggr_kprobe has
aggr_post_handler/aggr_break_handler whether the other kprobe
post_hander/break_handler is NULL or not.  This patch modifies this, only
when there is one or more kprobe in the list whose post_handler is not
NULL, post_handler of aggr_kprobe will be set as aggr_post_handler.

[soshima@redhat.com: !CONFIG_PREEMPT fix]
Signed-off-by: bibo, mao <bibo.mao@intel.com>
Cc: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp>
Cc: Hideo Aoki <haoki@redhat.com>
Signed-off-by: Satoshi Oshima <soshima@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 11 deletions

diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index 37f8623..727e419 100644
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -259,7 +259,9 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 	struct kprobe_ctlblk *kcb;
 #ifdef CONFIG_PREEMPT
 	unsigned pre_preempt_count = preempt_count();
-#endif /* CONFIG_PREEMPT */
+#else
+	unsigned pre_preempt_count = 1;
+#endif
 
 	addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
 
@@ -336,22 +338,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 		/* handler has already set things up, so skip ss setup */
 		return 1;
 
-	if (p->ainsn.boostable == 1 &&
-#ifdef CONFIG_PREEMPT
-	    !(pre_preempt_count) && /*
-				       * This enables booster when the direct
-				       * execution path aren't preempted.
-				       */
-#endif /* CONFIG_PREEMPT */
-	    !p->post_handler && !p->break_handler ) {
+ss_probe:
+	if (pre_preempt_count && p->ainsn.boostable == 1 && !p->post_handler){
 		/* Boost up -- we can execute copied instructions directly */
 		reset_current_kprobe();
 		regs->eip = (unsigned long)p->ainsn.insn;
 		preempt_enable_no_resched();
 		return 1;
 	}
-
-ss_probe:
 	prepare_singlestep(p, regs);
 	kcb->kprobe_status = KPROBE_HIT_SS;
 	return 1;