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ARM: SMP: use more sane register allocation for __fixup_smp_on_up 

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>
This commit is contained in:
Russell King 2010-11-22 12:06:28 +00:00
parent b54992fe1b
commit 0eb0511d17
1 changed files with 22 additions and 17 deletions
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39
arch/arm/kernel/head.S
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@ -89,6 +89,11 @@ ENTRY(stext)
bl __lookup_machine_type @ r5=machinfo
movs r8, r5 @ invalid machine (r5=0)?
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
@ -381,19 +386,19 @@ 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
@ -402,13 +407,13 @@ __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)