powerpc/ftrace: Fix nop of modules on 64bit LE (ABIv2)

There is a bug in the handling of the function entry when we are nopping
out a branch from a module in ftrace.

We compare the result of module_trampoline_target() with the value of
ppc_function_entry(), and expect them to be true. But they never will
be.

module_trampoline_target() will always return the global entry point of
the function, whereas ppc_function_entry() will always return the local.

Fix it by using the newly added ppc_global_function_entry().

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/ftrace.c

@@ -105,7 +105,7 @@ __ftrace_make_nop(struct module *mod,
 		  struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned int op;
-	unsigned long ptr;
+	unsigned long entry, ptr;
 	unsigned long ip = rec->ip;
 	void *tramp;
 
@@ -136,10 +136,11 @@ __ftrace_make_nop(struct module *mod,
 
 	pr_devel("trampoline target %lx", ptr);
 
+	entry = ppc_global_function_entry((void *)addr);
 	/* This should match what was called */
-	if (ptr != ppc_function_entry((void *)addr)) {
+	if (ptr != entry) {
 		printk(KERN_ERR "addr %lx does not match expected %lx\n",
-			ptr, ppc_function_entry((void *)addr));
+			ptr, entry);
 		return -EINVAL;
 	}