CRED: Wrap task credential accesses in the PowerPC arch

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: James Morris <jmorris@namei.org>

arch/powerpc/mm/fault.c

@@ -339,7 +339,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
 	    && printk_ratelimit())
 		printk(KERN_CRIT "kernel tried to execute NX-protected"
 		       " page (%lx) - exploit attempt? (uid: %d)\n",
-		       address, current->uid);
+		       address, current_uid());
 
 	return SIGSEGV;
 

arch/powerpc/platforms/cell/spufs/inode.c

@@ -95,8 +95,8 @@ spufs_new_inode(struct super_block *sb, int mode)
 		goto out;
 
 	inode->i_mode = mode;
-	inode->i_uid = current->fsuid;
-	inode->i_gid = current->fsgid;
+	inode->i_uid = current_fsuid();
+	inode->i_gid = current_fsgid();
 	inode->i_blocks = 0;
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 out: