From 4554dbcb85a4ed2abaa2b6fa15649b796699ec89 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@redhat.com>
Date: Tue, 2 Feb 2010 16:49:18 -0500
Subject: [PATCH] kprobes: Check probe address is reserved

Check whether the address of new probe is already reserved by
ftrace or alternatives (on x86) when registering new probe.
If reserved, it returns an error and not register the probe.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: przemyslaw@pawelczyk.it
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <20100202214918.4694.94179.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/kprobes.c | 3 +++
 kernel/kprobes.c          | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 9453815138fa..5de9f4a9c3fd 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -337,6 +337,9 @@ static void __kprobes arch_copy_kprobe(struct kprobe *p)
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
+	if (alternatives_text_reserved(p->addr, p->addr))
+		return -EINVAL;
+
 	if (!can_probe((unsigned long)p->addr))
 		return -EILSEQ;
 	/* insn: must be on special executable page on x86. */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9907a03c29f6..c3340e836c37 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -44,6 +44,7 @@
 #include <linux/debugfs.h>
 #include <linux/kdebug.h>
 #include <linux/memory.h>
+#include <linux/ftrace.h>
 
 #include <asm-generic/sections.h>
 #include <asm/cacheflush.h>
@@ -703,7 +704,8 @@ int __kprobes register_kprobe(struct kprobe *p)
 
 	preempt_disable();
 	if (!kernel_text_address((unsigned long) p->addr) ||
-	    in_kprobes_functions((unsigned long) p->addr)) {
+	    in_kprobes_functions((unsigned long) p->addr) ||
+	    ftrace_text_reserved(p->addr, p->addr)) {
 		preempt_enable();
 		return -EINVAL;
 	}