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From: Masami Hiramatsu on 2 Feb 2010 16:50
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(a)redhat.com>
Cc: Ingo Molnar <mingo(a)elte.hu>
Cc: Steven Rostedt <rostedt(a)goodmis.org>
Cc: Przemysław Pawełczyk <przemyslaw(a)pawelczyk.it>
Cc: Frederic Weisbecker <fweisbec(a)gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth(a)in.ibm.com>
Cc: Jim Keniston <jkenisto(a)us.ibm.com>
CC: Mathieu Desnoyers <compudj(a)krystal.dyndns.org>
Cc: Jason Baron <jbaron(a)redhat.com>
---

arch/x86/kernel/kprobes.c | 3 +++
kernel/kprobes.c | 4 +++-
2 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 9453815..5de9f4a 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 9907a03..c3340e8 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;
}


--
Masami Hiramatsu

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

e-mail: mhiramat(a)redhat.com
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