[PATCH -tip v11 03/27] kprobe: Simplify prepare_kprobe() by dropping redundant version

Masami Hiramatsu
2021-09-14T14:38:57Z

From: Punit Agrawal <punitagrawal@gmail.com>

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.

Signed-off-by: Punit Agrawal <punitagrawal@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
include/linux/kprobes.h | 5 +++++
kernel/kprobes.c | 23 +++++++++--------------
2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index e4f3bfe08757..0b75549b2815 100644
--- 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 26fc9904c3b1..cfa9d3c263eb 100644
--- 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)
{