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>

3 files changed, 38 insertions, 34 deletions

diff --git a/arch/arm/mm/proc-arm940.S b/arch/arm/mm/proc-arm940.S
index e5212d489377..c42cdd3b44bc 100644
--- a/arch/arm/mm/proc-arm940.S
+++ b/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
diff --git a/arch/arm/mm/proc-arm946.S b/arch/arm/mm/proc-arm946.S
index b3dd9b2d0b8e..17a8c2075c62 100644
--- a/arch/arm/mm/proc-arm946.S
+++ b/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
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S
index 082b9f2f7e90..d081c9d9420d 100644
--- a/arch/arm/mm/proc-macros.S
+++ b/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