LoongArch: Remove is_entry_func() and kernel_entry_end

For now, the related code of is_entry_func() is useless, so they can be
removed. Then the symbol kernel_entry_end is not used any more, so it can
be removed too.

Link: https://lore.kernel.org/lkml/kjiyla6qj3l7ezspitulrdoc5laj2e6hoecvd254hssnpddczm@g6nkaombh6va/
Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

Author: seehearfeel

arch/loongarch/kernel/head.S

@@ -144,5 +144,3 @@ SYM_CODE_START(smpboot_entry)
 SYM_CODE_END(smpboot_entry)
 
 #endif /* CONFIG_SMP */
-
-SYM_ENTRY(kernel_entry_end, SYM_L_GLOBAL, SYM_A_NONE)

arch/loongarch/kernel/unwind_orc.c

@@ -348,14 +348,6 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
 }
 EXPORT_SYMBOL_GPL(unwind_start);
 
-static bool is_entry_func(unsigned long addr)
-{
-	extern u32 kernel_entry;
-	extern u32 kernel_entry_end;
-
-	return addr >= (unsigned long)&kernel_entry && addr < (unsigned long)&kernel_entry_end;
-}
-
 static inline unsigned long bt_address(unsigned long ra)
 {
 	extern unsigned long eentry;
@@ -402,9 +394,6 @@ bool unwind_next_frame(struct unwind_state *state)
 	/* Don't let modules unload while we're reading their ORC data. */
 	guard(rcu)();
 
-	if (is_entry_func(state->pc))
-		goto end;
-
 	orc = orc_find(state->pc);
 	if (!orc) {
 		/*