kprobes: Add generic kretprobe trampoline handler

Add a generic kretprobe trampoline handler for unifying
the all cloned /arch/* kretprobe trampoline handlers.

The generic kretprobe trampoline handler is based on the
x86 implementation, because it is the latest implementation.
It has frame pointer checking, kprobe_busy_begin/end and
return address fixup for user handlers.

[ mingo: Minor edits. ]

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/159870600138.1229682.3424065380448088833.stgit@devnote2

1 files changed, 28 insertions, 4 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 9be1bff4f586..72142ae5df3e 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -187,10 +187,38 @@ static inline int kprobes_built_in(void)
 	return 1;
 }
 
+extern struct kprobe kprobe_busy;
+extern void kprobe_busy_begin(void);
+extern void kprobe_busy_end(void);
+
 #ifdef CONFIG_KRETPROBES
 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				   struct pt_regs *regs);
 extern int arch_trampoline_kprobe(struct kprobe *p);
+
+/* If the trampoline handler called from a kprobe, use this version */
+unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
+				void *trampoline_address,
+				void *frame_pointer);
+
+static nokprobe_inline
+unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
+				void *trampoline_address,
+				void *frame_pointer)
+{
+	unsigned long ret;
+	/*
+	 * Set a dummy kprobe for avoiding kretprobe recursion.
+	 * Since kretprobe never runs in kprobe handler, no kprobe must
+	 * be running at this point.
+	 */
+	kprobe_busy_begin();
+	ret = __kretprobe_trampoline_handler(regs, trampoline_address, frame_pointer);
+	kprobe_busy_end();
+
+	return ret;
+}
+
 #else /* CONFIG_KRETPROBES */
 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 					struct pt_regs *regs)
@@ -354,10 +382,6 @@ static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 	return this_cpu_ptr(&kprobe_ctlblk);
 }
 
-extern struct kprobe kprobe_busy;
-void kprobe_busy_begin(void);
-void kprobe_busy_end(void);
-
 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
 int register_kprobe(struct kprobe *p);
 void unregister_kprobe(struct kprobe *p);