ARM: make cr_alignment read-only #ifndef CONFIG_CPU_CP15

This makes cr_alignment a constant 0 to break code that tries to modify
the value as it's likely that it's built on wrong assumption when
CONFIG_CPU_CP15 isn't defined. For code that is only reading the value 0
is more or less a fine value to report.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Message-Id: 1358413196-5609-2-git-send-email-u.kleine-koenig@pengutronix.de (v8)

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index 854bd22380d3..5b391a689b47 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -98,8 +98,9 @@ __mmap_switched:
         str     r9, [r4]                        @ Save processor ID
         str     r1, [r5]                        @ Save machine type
         str     r2, [r6]                        @ Save atags pointer
-        bic     r4, r0, #CR_A                   @ Clear 'A' bit
-        stmia   r7, {r0, r4}                    @ Save control register values
+        cmp     r7, #0
+        bicne   r4, r0, #CR_A                   @ Clear 'A' bit
+        stmneia r7, {r0, r4}                    @ Save control register values
         b       start_kernel
 ENDPROC(__mmap_switched)
 
@@ -113,7 +114,11 @@ __mmap_switched_data:
         .long   processor_id                    @ r4
         .long   __machine_arch_type             @ r5
         .long   __atags_pointer                 @ r6
+#ifdef CONFIG_CPU_CP15
         .long   cr_alignment                    @ r7
+#else
+        .long   0                               @ r7
+#endif
         .long   init_thread_union + THREAD_START_SP @ sp
         .size   __mmap_switched_data, . - __mmap_switched_data