x86/entry/64: Use syscall wrappers for x32_rt_sigreturn

Add missing syscall wrapper for x32_rt_sigreturn().

Signed-off-by: Brian Gerst <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Reviewed-by: Dominik Brodowski <[e-mail]>
Reviewed-by: Andy Lutomirski <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

arch/x86/entry/syscalls/syscall_64.tbl

···
 # is defined.
 #
 512	x32	rt_sigaction		__x32_compat_sys_rt_sigaction
-513	x32	rt_sigreturn		sys32_x32_rt_sigreturn
+513	x32	rt_sigreturn		__x32_compat_sys_x32_rt_sigreturn
 514	x32	ioctl			__x32_compat_sys_ioctl
 515	x32	readv			__x32_compat_sys_readv
 516	x32	writev			__x32_compat_sys_writev

arch/x86/include/asm/sighandling.h

···
 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 		     struct pt_regs *regs, unsigned long mask);
 
-
-#ifdef CONFIG_X86_X32_ABI
-asmlinkage long sys32_x32_rt_sigreturn(void);
-#endif
-
 #endif /* _ASM_X86_SIGHANDLING_H */

arch/x86/kernel/signal.c

···
 }
 
 #ifdef CONFIG_X86_X32_ABI
-asmlinkage long sys32_x32_rt_sigreturn(void)
+COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
 {
 	struct pt_regs *regs = current_pt_regs();
 	struct rt_sigframe_x32 __user *frame;