ARM: proc-arm94*.S: fix setup function

Both ARM946 and ARM940 setup functions were corrupting r1 and r2,
which is not permissible - these are used to carry the machine ID
and boot data into the kernel, and must be preserved.

The code responsible for this was the same in both files: they were
using the registers to generate a protection region register value.

Fix this by turning this process into a macro, and using that macro
in both these files with an alternative register allocation.  r0,
r3 and r7 can be used for temporary values here.

Reported-by: Alex Dumitrache <broscutamaker@gmail.com>
Tested-by: Georg Hofstetter <g3gg0.de@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/proc-macros.S

@@ -331,3 +331,27 @@ ENTRY(\name\()_tlb_fns)
 	.globl	\x
 	.equ	\x, \y
 .endm
+
+	/*
+	 * Macro to calculate the log2 size for the protection region
+	 * registers. This calculates rd = log2(size) - 1.  tmp must
+	 * not be the same register as rd.
+	 */
+.macro	pr_sz, rd, size, tmp
+	mov	\tmp, \size, lsr #12
+	mov	\rd, #11
+1:	movs	\tmp, \tmp, lsr #1
+	addne	\rd, \rd, #1
+	bne	1b
+.endm
+
+	/*
+	 * Macro to generate a protection region register value
+	 * given a pre-masked address, size, and enable bit.
+	 * Corrupts size.
+	 */
+.macro	pr_val, dest, addr, size, enable
+	pr_sz	\dest, \size, \size		@ calculate log2(size) - 1
+	orr	\dest, \addr, \dest, lsl #1	@ mask in the region size
+	orr	\dest, \dest, \enable
+.endm