x86: Use helpers for rlimits

Make sure compiler won't do weird things with limits. Fetching them
twice may return 2 different values after writable limits are
implemented.

We can either use rlimit helpers added in
3e10e716abf3c71bdb5d86b8f507f9e72236c9cd or ACCESS_ONCE if not
applicable; this patch uses the helpers.

Signed-off-by: Jiri Slaby <[e-mail]>
LKML-Reference: <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/ia32/ia32_aout.c

···
 	 * size limits imposed on them by creating programs with large
 	 * arrays in the data or bss.
 	 */
-	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
+	rlim = rlimit(RLIMIT_DATA);
 	if (rlim >= RLIM_INFINITY)
 		rlim = ~0;
 	if (ex.a_data + ex.a_bss > rlim)

arch/x86/mm/mmap.c

···
 	if (current->personality & ADDR_COMPAT_LAYOUT)
 		return 1;
 
-	if (current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY)
+	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
 		return 1;
 
 	return sysctl_legacy_va_layout;
···
 
 static unsigned long mmap_base(void)
 {
-	unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
+	unsigned long gap = rlimit(RLIMIT_STACK);
 
 	if (gap < MIN_GAP)
 		gap = MIN_GAP;