um: simplify syscall header files

Since Thomas's recent commit 2af10530639b ("um/x86: Add
system call table to header file") , we now have two
extern declarations of the syscall table, one internal
and one external, and they don't even match on 32-bit.
Clean this up and remove all the extra code.

Reviewed-by: Thomas Weißschuh <[e-mail]>
Link: https://patch.msgid.link/20250704141243.a68366f6acc3.If8587a4aafdb90644fc6d0b2f5e31a2d1887915f@changeid
Signed-off-by: Johannes Berg <[e-mail]>

arch/um/kernel/skas/syscall.c

···
 #include <kern_util.h>
 #include <sysdep/ptrace.h>
 #include <sysdep/ptrace_user.h>
-#include <sysdep/syscalls.h>
 #include <linux/time-internal.h>
+#include <asm/syscall.h>
 #include <asm/unistd.h>
 #include <asm/delay.h>
 
···
 		tt_extra_sched_jiffies += 1;
 
 	if (syscall >= 0 && syscall < __NR_syscalls) {
-		unsigned long ret = EXECUTE_SYSCALL(syscall, regs);
+		unsigned long ret;
+
+		ret = (*sys_call_table[syscall])(UPT_SYSCALL_ARG1(&regs->regs),
+						 UPT_SYSCALL_ARG2(&regs->regs),
+						 UPT_SYSCALL_ARG3(&regs->regs),
+						 UPT_SYSCALL_ARG4(&regs->regs),
+						 UPT_SYSCALL_ARG5(&regs->regs),
+						 UPT_SYSCALL_ARG6(&regs->regs));
 
 		PT_REGS_SET_SYSCALL_RETURN(regs, ret);
 

arch/x86/um/shared/sysdep/ptrace.h

···
 #include "ptrace_64.h"
 #endif
 
-struct syscall_args {
-	unsigned long args[6];
-};
-
-#define SYSCALL_ARGS(r) ((struct syscall_args) \
-			 { .args = { UPT_SYSCALL_ARG1(r),	 \
-				     UPT_SYSCALL_ARG2(r),	 \
-				     UPT_SYSCALL_ARG3(r),	 \
-				     UPT_SYSCALL_ARG4(r),	 \
-				     UPT_SYSCALL_ARG5(r),	 \
-				     UPT_SYSCALL_ARG6(r) } } )
-
 extern unsigned long host_fp_size;
 
 struct uml_pt_regs {

arch/x86/um/shared/sysdep/syscalls.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifdef __i386__
-#include "syscalls_32.h"
-#else
-#include "syscalls_64.h"
-#endif

arch/x86/um/shared/sysdep/syscalls_32.h

···
-/* 
- * Copyright (C) 2000 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
- */
-
-#include <asm/unistd.h>
-#include <sysdep/ptrace.h>
-
-typedef long syscall_handler_t(struct syscall_args);
-
-extern syscall_handler_t *sys_call_table[];
-
-#define EXECUTE_SYSCALL(syscall, regs) \
-	((*sys_call_table[syscall]))(SYSCALL_ARGS(&regs->regs))

arch/x86/um/shared/sysdep/syscalls_64.h

···
-/*
- * Copyright 2003 PathScale, Inc.
- *
- * Licensed under the GPL
- */
-
-#ifndef __SYSDEP_X86_64_SYSCALLS_H__
-#define __SYSDEP_X86_64_SYSCALLS_H__
-
-#include <linux/msg.h>
-#include <linux/shm.h>
-
-typedef long syscall_handler_t(long, long, long, long, long, long);
-
-extern syscall_handler_t *sys_call_table[];
-
-#define EXECUTE_SYSCALL(syscall, regs) \
-	(((*sys_call_table[syscall]))(UPT_SYSCALL_ARG1(&regs->regs), \
-		 		      UPT_SYSCALL_ARG2(&regs->regs), \
-				      UPT_SYSCALL_ARG3(&regs->regs), \
-				      UPT_SYSCALL_ARG4(&regs->regs), \
-				      UPT_SYSCALL_ARG5(&regs->regs), \
-				      UPT_SYSCALL_ARG6(&regs->regs)))
-
-extern syscall_handler_t sys_modify_ldt;
-extern syscall_handler_t sys_arch_prctl;
-
-#endif