diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c
index 2b13f1c842b8..6e00929b893c 100644
--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -41,7 +41,7 @@ const sys_call_ptr_t sys_call_table[] = {
 #endif
 
 #define __SYSCALL(nr, sym) case nr: return __ia32_##sym(regs);
-long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)
+static noinline long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)
 {
 	switch (nr) {
 	#include <asm/syscalls_32.h>
diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
index 0acd7e99e8e0..837aee7db50d 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -32,7 +32,7 @@ const sys_call_ptr_t sys_call_table[] = {
 #undef  __SYSCALL
 
 #define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);
-long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
+static noinline long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
 {
 	switch (nr) {
 	#include <asm/syscalls_64.h>
@@ -40,15 +40,17 @@ long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
 	}
 }
 
-#ifdef CONFIG_X86_X32_ABI
-long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
+static noinline long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
 {
+#ifdef CONFIG_X86_X32_ABI
 	switch (nr) {
 	#include <asm/syscalls_x32.h>
 	default: return __x64_sys_ni_syscall(regs);
 	}
-}
+#else
+	return -ENOSYS;
 #endif
+}
 
 static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr)
 {
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index c10dbb74cd00..59a406074dc0 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -20,14 +20,6 @@
 typedef long (*sys_call_ptr_t)(const struct pt_regs *);
 extern const sys_call_ptr_t sys_call_table[];
 
-/*
- * These may not exist, but still put the prototypes in so we
- * can use IS_ENABLED().
- */
-extern long ia32_sys_call(const struct pt_regs *, unsigned int nr);
-extern long x32_sys_call(const struct pt_regs *, unsigned int nr);
-extern long x64_sys_call(const struct pt_regs *, unsigned int nr);
-
 /*
  * Only the low 32 bits of orig_ax are meaningful, so we return int.
  * This importantly ignores the high bits on 64-bit, so comparisons