um: Remove SKAS3/4 support

Before we had SKAS0 UML had two modes of operation
TT (tracing thread) and SKAS3/4 (separated kernel address space).
TT was known to be insecure and got removed a long time ago.
SKAS3/4 required a few (3 or 4) patches on the host side which never went
mainline. The last host patch is 10 years old.

With SKAS0 mode (separated kernel address space using 0 host patches),
default since 2005, SKAS3/4 is obsolete and can be removed.

Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/kernel/ptrace.c

@@ -8,9 +8,6 @@
 #include <linux/sched.h>
 #include <linux/tracehook.h>
 #include <asm/uaccess.h>
-#include <skas_ptrace.h>
-
-
 
 void user_enable_single_step(struct task_struct *child)
 {
@@ -104,35 +101,6 @@ long arch_ptrace(struct task_struct *child, long request,
 		ret = ptrace_set_thread_area(child, addr, vp);
 		break;
 
-	case PTRACE_FAULTINFO: {
-		/*
-		 * Take the info from thread->arch->faultinfo,
-		 * but transfer max. sizeof(struct ptrace_faultinfo).
-		 * On i386, ptrace_faultinfo is smaller!
-		 */
-		ret = copy_to_user(p, &child->thread.arch.faultinfo,
-				   sizeof(struct ptrace_faultinfo)) ?
-			-EIO : 0;
-		break;
-	}
-
-#ifdef PTRACE_LDT
-	case PTRACE_LDT: {
-		struct ptrace_ldt ldt;
-
-		if (copy_from_user(&ldt, p, sizeof(ldt))) {
-			ret = -EIO;
-			break;
-		}
-
-		/*
-		 * This one is confusing, so just punt and return -EIO for
-		 * now
-		 */
-		ret = -EIO;
-		break;
-	}
-#endif
 	default:
 		ret = ptrace_request(child, request, addr, data);
 		if (ret == -EIO)