linux-kernel - [PATCH 2/3] x86: add reenter

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Date:	Wed, 19 Dec 2007 16:48:54 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Jim Keniston <jkenisto@...ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Harvey Harrison <harvey.harrison@...il.com>
CC:	Roland McGrath <roland@...hat.com>,
	Arjan van de Ven <arjan@...radead.org>,
	prasanna@...ibm.com, anil.s.keshavamurthy@...el.com,
	davem@...emloft.net, systemtap-ml <systemtap@...rces.redhat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/3] x86: add reenter_kprobe helper

From:  Harvey Harrison <harvey.harrison@...il.com>

[ mhiramat@...hat.com: updated it to latest x86.git ]

Factor common X86_32, X86_64 kprobe reenter logic from deeply
indented section to helper function.

Signed-off-by: Harvey Harrison <harvey.harrison@...il.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Jim Keniston <jkenisto@...ibm.com>
---

 arch/x86/kernel/kprobes.c |   26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

Index: b/arch/x86/kernel/kprobes.c
===================================================================
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -427,6 +427,20 @@ void __kprobes arch_prepare_kretprobe(st
 	/* Replace the return addr with trampoline addr */
 	*sara = (unsigned long) &kretprobe_trampoline;
 }
+/*
+ * We have reentered the kprobe_handler(), since another probe was hit while
+ * within the handler. We save the original kprobes variables and just single
+ * step on the instruction of the new probe without calling any user handlers.
+ */
+static void __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
+				     struct kprobe_ctlblk *kcb)
+{
+	save_previous_kprobe(kcb);
+	set_current_kprobe(p, regs, kcb);
+	kprobes_inc_nmissed_count(p);
+	prepare_singlestep(p, regs);
+	kcb->kprobe_status = KPROBE_REENTER;
+}

 /*
  * Interrupts are disabled on entry as trap3 is an interrupt gate and they
@@ -471,17 +485,7 @@ static int __kprobes kprobe_handler(stru
 				goto no_kprobe;
 #endif
 			}
-			/* We have reentered the kprobe_handler(), since
-			 * another probe was hit while within the handler.
-			 * We here save the original kprobes variables and
-			 * just single step on the instruction of the new probe
-			 * without calling any user handlers.
-			 */
-			save_previous_kprobe(kcb);
-			set_current_kprobe(p, regs, kcb);
-			kprobes_inc_nmissed_count(p);
-			prepare_singlestep(p, regs);
-			kcb->kprobe_status = KPROBE_REENTER;
+			reenter_kprobe(p, regs, kcb);
 			return 1;
 		} else {
 			if (*addr != BREAKPOINT_INSTRUCTION) {
-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com, masami.hiramatsu.pt@...achi.com
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