linux-kernel - [PATCH v3 1/2] kprobes: introduce weak arch_check_ftrace

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Message-Id: <1413880229-4796-2-git-send-email-heiko.carstens@de.ibm.com>
Date:	Tue, 21 Oct 2014 10:30:28 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Ingo Molnar <mingo@...hat.com>
Cc:	Vojtech Pavlik <vojtech@...e.cz>, Jiri Kosina <jkosina@...e.cz>,
	Jiri Slaby <jslaby@...e.cz>,
	Steven Rostedt <rostedt@...dmis.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	linux-kernel@...r.kernel.org,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: [PATCH v3 1/2] kprobes: introduce weak arch_check_ftrace_location() helper function

Introduce weak arch_check_ftrace_location() helper function which
architectures can override in order to implement handling of kprobes
on function tracer call sites on their own, without depending on
common code or implementing the KPROBES_ON_FTRACE feature.

Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
---
 include/linux/kprobes.h |  1 +
 kernel/kprobes.c        | 18 +++++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index f7296e57d614..5297f9fa0ef2 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -335,6 +335,7 @@ extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
 #endif
 
+int arch_check_ftrace_location(struct kprobe *p);
 
 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 struct kprobe *get_kprobe(void *addr);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3995f546d0f3..317eb8ad28dd 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1410,16 +1410,10 @@ static inline int check_kprobe_rereg(struct kprobe *p)
 	return ret;
 }
 
-static int check_kprobe_address_safe(struct kprobe *p,
-				     struct module **probed_mod)
+int __weak arch_check_ftrace_location(struct kprobe *p)
 {
-	int ret = 0;
 	unsigned long ftrace_addr;
 
-	/*
-	 * If the address is located on a ftrace nop, set the
-	 * breakpoint to the following instruction.
-	 */
 	ftrace_addr = ftrace_location((unsigned long)p->addr);
 	if (ftrace_addr) {
 #ifdef CONFIG_KPROBES_ON_FTRACE
@@ -1431,7 +1425,17 @@ static int check_kprobe_address_safe(struct kprobe *p,
 		return -EINVAL;
 #endif
 	}
+	return 0;
+}
 
+static int check_kprobe_address_safe(struct kprobe *p,
+				     struct module **probed_mod)
+{
+	int ret;
+
+	ret = arch_check_ftrace_location(p);
+	if (ret)
+		return ret;
 	jump_label_lock();
 	preempt_disable();
 
-- 
1.8.5.5

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