powerpc/ftrace: Remove mod_return_to_handler

mod_return_to_handler is the same as return_to_handler, except
it handles the change of the TOC (r2). Add this into
return_to_handler and remove mod_return_to_handler.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/entry_64.S

@@ -1240,28 +1240,6 @@ _GLOBAL(ftrace_graph_caller)
 	blr
 
 _GLOBAL(return_to_handler)
-	/* need to save return values */
-	std	r4,  -24(r1)
-	std	r3,  -16(r1)
-	std	r31, -8(r1)
-	mr	r31, r1
-	stdu	r1, -112(r1)
-
-	bl	ftrace_return_to_handler
-	nop
-
-	/* return value has real return address */
-	mtlr	r3
-
-	ld	r1, 0(r1)
-	ld	r4,  -24(r1)
-	ld	r3,  -16(r1)
-	ld	r31, -8(r1)
-
-	/* Jump back to real return address */
-	blr
-
-_GLOBAL(mod_return_to_handler)
 	/* need to save return values */
 	std	r4,  -32(r1)
 	std	r3,  -24(r1)
@@ -1272,7 +1250,7 @@ _GLOBAL(mod_return_to_handler)
 	stdu	r1, -112(r1)
 
 	/*
-	 * We are in a module using the module's TOC.
+	 * We might be called from a module.
 	 * Switch to our TOC to run inside the core kernel.
 	 */
 	ld	r2, PACATOC(r13)

arch/powerpc/kernel/ftrace.c

@@ -510,10 +510,6 @@ int ftrace_disable_ftrace_graph_caller(void)
 }
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
-#ifdef CONFIG_PPC64
-extern void mod_return_to_handler(void);
-#endif
-
 /*
  * Hook the return address and push it in the stack of return addrs
  * in current thread info.
@@ -523,7 +519,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
 	unsigned long old;
 	int faulted;
 	struct ftrace_graph_ent trace;
-	unsigned long return_hooker = (unsigned long)&return_to_handler;
+	unsigned long return_hooker;
 
 	if (unlikely(ftrace_graph_is_dead()))
 		return;
@@ -531,13 +527,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
 
-#ifdef CONFIG_PPC64
-	/* non core kernel code needs to save and restore the TOC */
-	if (REGION_ID(self_addr) != KERNEL_REGION_ID)
-		return_hooker = (unsigned long)&mod_return_to_handler;
-#endif
-
-	return_hooker = ppc_function_entry((void *)return_hooker);
+	return_hooker = ppc_function_entry(return_to_handler);
 
 	/*
 	 * Protect against fault, even if it shouldn't

arch/powerpc/kernel/process.c

@@ -1527,13 +1527,6 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
 	int curr_frame = current->curr_ret_stack;
 	extern void return_to_handler(void);
 	unsigned long rth = (unsigned long)return_to_handler;
-	unsigned long mrth = -1;
-#ifdef CONFIG_PPC64
-	extern void mod_return_to_handler(void);
-	rth = *(unsigned long *)rth;
-	mrth = (unsigned long)mod_return_to_handler;
-	mrth = *(unsigned long *)mrth;
-#endif
 #endif
 
 	sp = (unsigned long) stack;
@@ -1558,7 +1551,7 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
 		if (!firstframe || ip != lr) {
 			printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-			if ((ip == rth || ip == mrth) && curr_frame >= 0) {
+			if ((ip == rth) && curr_frame >= 0) {
 				printk(" (%pS)",
 				       (void *)current->ret_stack[curr_frame].ret);
 				curr_frame--;