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-arm940.S

@@ -297,26 +297,16 @@ __arm940_setup:
 	mcr	p15, 0, r0, c6,	c0, 1
 
 	ldr	r0, =(CONFIG_DRAM_BASE & 0xFFFFF000) @ base[31:12] of RAM
-	ldr	r1, =(CONFIG_DRAM_SIZE >> 12)	@ size of RAM (must be >= 4KB)
-	mov	r2, #10				@ 11 is the minimum (4KB)
-1:	add	r2, r2, #1			@ area size *= 2
-	mov	r1, r1, lsr #1
-	bne	1b				@ count not zero r-shift
-	orr	r0, r0, r2, lsl #1		@ the area register value
-	orr	r0, r0, #1			@ set enable bit
-	mcr	p15, 0, r0, c6,	c1, 0		@ set area 1, RAM
-	mcr	p15, 0, r0, c6,	c1, 1
+	ldr	r7, =CONFIG_DRAM_SIZE >> 12	@ size of RAM (must be >= 4KB)
+	pr_val	r3, r0, r7, #1
+	mcr	p15, 0, r3, c6,	c1, 0		@ set area 1, RAM
+	mcr	p15, 0, r3, c6,	c1, 1
 
 	ldr	r0, =(CONFIG_FLASH_MEM_BASE & 0xFFFFF000) @ base[31:12] of FLASH
-	ldr	r1, =(CONFIG_FLASH_SIZE >> 12)	@ size of FLASH (must be >= 4KB)
-	mov	r2, #10				@ 11 is the minimum (4KB)
-1:	add	r2, r2, #1			@ area size *= 2
-	mov	r1, r1, lsr #1
-	bne	1b				@ count not zero r-shift
-	orr	r0, r0, r2, lsl #1		@ the area register value
-	orr	r0, r0, #1			@ set enable bit
-	mcr	p15, 0, r0, c6,	c2, 0		@ set area 2, ROM/FLASH
-	mcr	p15, 0, r0, c6,	c2, 1
+	ldr	r7, =CONFIG_FLASH_SIZE		@ size of FLASH (must be >= 4KB)
+	pr_val	r3, r0, r6, #1
+	mcr	p15, 0, r3, c6,	c2, 0		@ set area 2, ROM/FLASH
+	mcr	p15, 0, r3, c6,	c2, 1
 
 	mov	r0, #0x06
 	mcr	p15, 0, r0, c2, c0, 0		@ Region 1&2 cacheable

arch/arm/mm/proc-arm946.S

@@ -343,24 +343,14 @@ __arm946_setup:
 	mcr	p15, 0, r0, c6,	c0, 0		@ set region 0, default
 
 	ldr	r0, =(CONFIG_DRAM_BASE & 0xFFFFF000) @ base[31:12] of RAM
-	ldr	r1, =(CONFIG_DRAM_SIZE >> 12)	@ size of RAM (must be >= 4KB)
-	mov	r2, #10				@ 11 is the minimum (4KB)
-1:	add	r2, r2, #1			@ area size *= 2
-	mov	r1, r1, lsr #1
-	bne	1b				@ count not zero r-shift
-	orr	r0, r0, r2, lsl #1		@ the region register value
-	orr	r0, r0, #1			@ set enable bit
-	mcr	p15, 0, r0, c6,	c1, 0		@ set region 1, RAM
+	ldr	r7, =CONFIG_DRAM_SIZE		@ size of RAM (must be >= 4KB)
+	pr_val	r3, r0, r7, #1
+	mcr	p15, 0, r3, c6, c1, 0
 
 	ldr	r0, =(CONFIG_FLASH_MEM_BASE & 0xFFFFF000) @ base[31:12] of FLASH
-	ldr	r1, =(CONFIG_FLASH_SIZE >> 12)	@ size of FLASH (must be >= 4KB)
-	mov	r2, #10				@ 11 is the minimum (4KB)
-1:	add	r2, r2, #1			@ area size *= 2
-	mov	r1, r1, lsr #1
-	bne	1b				@ count not zero r-shift
-	orr	r0, r0, r2, lsl #1		@ the region register value
-	orr	r0, r0, #1			@ set enable bit
-	mcr	p15, 0, r0, c6,	c2, 0		@ set region 2, ROM/FLASH
+	ldr	r7, =CONFIG_FLASH_SIZE		@ size of FLASH (must be >= 4KB)
+	pr_val	r3, r0, r7, #1
+	mcr	p15, 0, r3, c6, c2, 0
 
 	mov	r0, #0x06
 	mcr	p15, 0, r0, c2, c0, 0		@ region 1,2 d-cacheable

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