Fix broken fsys_getppid()

In particular fsys_getppid always returns the ppid in the initial pid
namespace so it does not work for a process in a pid namespace.

Fix from Eric Biederman just removes the fast system call path.
While it is a little bit sad to see another one of these bite
the dust ... I can't imagine that getppid() is really on any
real applications critical path.

Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/fsys.S

@@ -90,53 +90,6 @@ ENTRY(fsys_getpid)
 	FSYS_RETURN
 END(fsys_getpid)
 
-ENTRY(fsys_getppid)
-	.prologue
-	.altrp b6
-	.body
-	add r17=IA64_TASK_GROUP_LEADER_OFFSET,r16
-	;;
-	ld8 r17=[r17]				// r17 = current->group_leader
-	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
-	;;
-
-	ld4 r9=[r9]
-	add r17=IA64_TASK_REAL_PARENT_OFFSET,r17 // r17 = &current->group_leader->real_parent
-	;;
-	and r9=TIF_ALLWORK_MASK,r9
-
-1:	ld8 r18=[r17]				// r18 = current->group_leader->real_parent
-	;;
-	cmp.ne p8,p0=0,r9
-	add r8=IA64_TASK_TGID_OFFSET,r18	// r8 = &current->group_leader->real_parent->tgid
-	;;
-
-	/*
-	 * The .acq is needed to ensure that the read of tgid has returned its data before
-	 * we re-check "real_parent".
-	 */
-	ld4.acq r8=[r8]				// r8 = current->group_leader->real_parent->tgid
-#ifdef CONFIG_SMP
-	/*
-	 * Re-read current->group_leader->real_parent.
-	 */
-	ld8 r19=[r17]				// r19 = current->group_leader->real_parent
-(p8)	br.spnt.many fsys_fallback_syscall
-	;;
-	cmp.ne p6,p0=r18,r19			// did real_parent change?
-	mov r19=0			// i must not leak kernel bits...
-(p6)	br.cond.spnt.few 1b			// yes -> redo the read of tgid and the check
-	;;
-	mov r17=0			// i must not leak kernel bits...
-	mov r18=0			// i must not leak kernel bits...
-#else
-	mov r17=0			// i must not leak kernel bits...
-	mov r18=0			// i must not leak kernel bits...
-	mov r19=0			// i must not leak kernel bits...
-#endif
-	FSYS_RETURN
-END(fsys_getppid)
-
 ENTRY(fsys_set_tid_address)
 	.prologue
 	.altrp b6
@@ -614,7 +567,7 @@ paravirt_fsyscall_table:
 	data8 0				// chown
 	data8 0				// lseek		// 1040
 	data8 fsys_getpid		// getpid
-	data8 fsys_getppid		// getppid
+	data8 0				// getppid
 	data8 0				// mount
 	data8 0				// umount
 	data8 0				// setuid		// 1045