[196/272] ARM: SMP: use more sane register allocation for __fixup_smp_on_up

Greg KH
2011-02-16T00:40:50Z

From: Russell King <rmk+kernel@arm.linux.org.uk>

commit 0eb0511d176534674600a1986c3c766756288908 upstream.

Use r0,r3-r6 rather than r0,r3,r4,r6,r7, which makes it easier to
understand which registers can be modified. Also document which
registers hold values which must be preserved.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/arm/kernel/head.S | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)

--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -91,6 +91,11 @@ ENTRY(stext)
movs r8, r5 @ invalid machine (r5=0)?
THUMB( it eq ) @ force fixup-able long branch encoding
beq __error_a @ yes, error 'a'
+
+ /*
+ * r1 = machine no, r2 = atags,
+ * r8 = machinfo, r9 = cpuid, r10 = procinfo
+ */
bl __vet_atags
#ifdef CONFIG_SMP_ON_UP
bl __fixup_smp
@@ -387,19 +392,19 @@ ENDPROC(__turn_mmu_on)

#ifdef CONFIG_SMP_ON_UP
__fixup_smp:
- mov r7, #0x00070000
- orr r6, r7, #0xff000000 @ mask 0xff070000
- orr r7, r7, #0x41000000 @ val 0x41070000
- and r0, r9, r6
- teq r0, r7 @ ARM CPU and ARMv6/v7?
+ mov r4, #0x00070000
+ orr r3, r4, #0xff000000 @ mask 0xff070000
+ orr r4, r4, #0x41000000 @ val 0x41070000
+ and r0, r9, r3
+ teq r0, r4 @ ARM CPU and ARMv6/v7?
bne __fixup_smp_on_up @ no, assume UP

- orr r6, r6, #0x0000ff00
- orr r6, r6, #0x000000f0 @ mask 0xff07fff0
- orr r7, r7, #0x0000b000
- orr r7, r7, #0x00000020 @ val 0x4107b020
- and r0, r9, r6
- teq r0, r7 @ ARM 11MPCore?
+ orr r3, r3, #0x0000ff00
+ orr r3, r3, #0x000000f0 @ mask 0xff07fff0
+ orr r4, r4, #0x0000b000
+ orr r4, r4, #0x00000020 @ val 0x4107b020
+ and r0, r9, r3
+ teq r0, r4 @ ARM 11MPCore?
moveq pc, lr @ yes, assume SMP

mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
@@ -408,13 +413,13 @@ __fixup_smp:

__fixup_smp_on_up:
adr r0, 1f
- ldmia r0, {r3, r6, r7}
+ ldmia r0, {r3 - r5}
sub r3, r0, r3
- add r6, r6, r3
- add r7, r7, r3
-2: cmp r6, r7
- ldmia r6!, {r0, r4}
- strlo r4, [r0, r3]
+ add r4, r4, r3
+ add r5, r5, r3
+2: cmp r4, r5
+ ldmia r4!, {r0, r6}
+ strlo r6, [r0, r3]
blo 2b
mov pc, lr
ENDPROC(__fixup_smp)