ARM: make the physical-relative calculation more obvious

The physical-relative calculation between the XIP text and data sections
introduced by the previous patch was far from obvious. Let's simplify it
by turning it into a macro which takes the two (virtual) addresses.

This allows us to arrange the calculation in a more obvious manner - we
can make it two sub-expressions which calculate the physical address for
each symbol, and then takes the difference of those physical addresses.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/memory.h

@@ -135,11 +135,18 @@
 #define PLAT_PHYS_OFFSET	UL(CONFIG_PHYS_OFFSET)
 
 #ifdef CONFIG_XIP_KERNEL
-#define PHYS_OFFSET_FIXUP \
-	( XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) - PAGE_OFFSET + \
-	  PLAT_PHYS_OFFSET - CONFIG_XIP_PHYS_ADDR )
+/*
+ * When referencing data in RAM from the XIP region in a relative manner
+ * with the MMU off, we need the relative offset between the two physical
+ * addresses.  The macro below achieves this, which is:
+ *    __pa(v_data) - __xip_pa(v_text)
+ */
+#define PHYS_RELATIVE(v_data, v_text) \
+	(((v_data) - PAGE_OFFSET + PLAT_PHYS_OFFSET) - \
+	 ((v_text) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) + \
+          CONFIG_XIP_PHYS_ADDR))
 #else
-#define PHYS_OFFSET_FIXUP 0
+#define PHYS_RELATIVE(v_data, v_text) ((v_data) - (v_text))
 #endif
 
 #ifndef __ASSEMBLY__

arch/arm/mm/proc-v7.S

@@ -487,7 +487,7 @@ __errata_finish:
 
 	.align	2
 __v7_setup_stack_ptr:
-	.word	__v7_setup_stack - . + PHYS_OFFSET_FIXUP
+	.word	PHYS_RELATIVE(__v7_setup_stack, .)
 ENDPROC(__v7_setup)
 
 	.bss