linux-kernel - [PATCH v3 3/5] kprobes: Skip preparing optprobe if the probe is ftrace-based

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Message-Id: <7f7a8996838c31dd294dea11a639390ddd245291.1491994965.git.naveen.n.rao@linux.vnet.ibm.com>
Date:   Wed, 12 Apr 2017 16:39:24 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 3/5] kprobes: Skip preparing optprobe if the probe is ftrace-based

From: Masami Hiramatsu <mhiramat@...nel.org>

Skip preparing optprobe if the probe is ftrace-based, since anyway, it
must not be optimized (or already optimized by ftrace).

Tested-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
Though this patch is generic, it is needed for KPROBES_ON_FTRACE to work
on powerpc.

- Naveen


 kernel/kprobes.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 6a128f3a7ed1..406889889ce5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -743,13 +743,20 @@ static void kill_optimized_kprobe(struct kprobe *p)
 	arch_remove_optimized_kprobe(op);
 }
 
+static inline
+void __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
+{
+	if (!kprobe_ftrace(p))
+		arch_prepare_optimized_kprobe(op, p);
+}
+
 /* Try to prepare optimized instructions */
 static void prepare_optimized_kprobe(struct kprobe *p)
 {
 	struct optimized_kprobe *op;
 
 	op = container_of(p, struct optimized_kprobe, kp);
-	arch_prepare_optimized_kprobe(op, p);
+	__prepare_optimized_kprobe(op, p);
 }
 
 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
@@ -763,7 +770,7 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 
 	INIT_LIST_HEAD(&op->list);
 	op->kp.addr = p->addr;
-	arch_prepare_optimized_kprobe(op, p);
+	__prepare_optimized_kprobe(op, p);
 
 	return &op->kp;
 }
-- 
2.12.1