kprobe: Simplify prepare_kprobe() by dropping redundant version

The function prepare_kprobe() is called during kprobe registration and
is responsible for ensuring any architecture related preparation for
the kprobe is done before returning.

One of two versions of prepare_kprobe() is chosen depending on the
availability of KPROBE_ON_FTRACE in the kernel configuration.

Simplify the code by dropping the version when KPROBE_ON_FTRACE is not
selected - instead relying on kprobe_ftrace() to return false when
KPROBE_ON_FTRACE is not set.

No functional change.

Link: https://lkml.kernel.org/r/163163033696.489837.9264661820279300788.stgit@devnote2
Signed-off-by: Punit Agrawal <punitagrawal@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index e4f3bfe..0b75549 100644 (file)
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -354,6 +354,11 @@ static inline void wait_for_kprobe_optimizer(void) { }
 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
                                  struct ftrace_ops *ops, struct ftrace_regs *fregs);
 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
+#else
+static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+       return -EINVAL;
+}
 #endif
 
 int arch_check_ftrace_location(struct kprobe *p);

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 26fc990..cfa9d3c 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1033,15 +1033,6 @@ static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
 static int kprobe_ipmodify_enabled;
 static int kprobe_ftrace_enabled;
 
-/* Must ensure p->addr is really on ftrace */
-static int prepare_kprobe(struct kprobe *p)
-{
-       if (!kprobe_ftrace(p))
-               return arch_prepare_kprobe(p);
-
-       return arch_prepare_kprobe_ftrace(p);
-}
-
 /* Caller must lock kprobe_mutex */
 static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
                               int *cnt)
@@ -1113,11 +1104,6 @@ static int disarm_kprobe_ftrace(struct kprobe *p)
                ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
 }
 #else  /* !CONFIG_KPROBES_ON_FTRACE */
-static inline int prepare_kprobe(struct kprobe *p)
-{
-       return arch_prepare_kprobe(p);
-}
-
 static inline int arm_kprobe_ftrace(struct kprobe *p)
 {
        return -ENODEV;
@@ -1129,6 +1115,15 @@ static inline int disarm_kprobe_ftrace(struct kprobe *p)
 }
 #endif
 
+static int prepare_kprobe(struct kprobe *p)
+{
+       /* Must ensure p->addr is really on ftrace */
+       if (kprobe_ftrace(p))
+               return arch_prepare_kprobe_ftrace(p);
+
+       return arch_prepare_kprobe(p);
+}
+
 /* Arm a kprobe with text_mutex */
 static int arm_kprobe(struct kprobe *kp)
 {