alistair23-linux/arch/arm/mach-shmobile/headsmp.S

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/*
* SMP support for R-Mobile / SH-Mobile
*
* Copyright (C) 2010 Magnus Damm
* Copyright (C) 2010 Takashi Yoshii
*
* Based on vexpress, Copyright (c) 2003 ARM Limited, All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/threads.h>
ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ ARMv6 and greater introduced a new instruction ("bx") which can be used to return from function calls. Recent CPUs perform better when the "bx lr" instruction is used rather than the "mov pc, lr" instruction, and this sequence is strongly recommended to be used by the ARM architecture manual (section A.4.1.1). We provide a new macro "ret" with all its variants for the condition code which will resolve to the appropriate instruction. Rather than doing this piecemeal, and miss some instances, change all the "mov pc" instances to use the new macro, with the exception of the "movs" instruction and the kprobes code. This allows us to detect the "mov pc, lr" case and fix it up - and also gives us the possibility of deploying this for other registers depending on the CPU selection. Reported-by: Will Deacon <will.deacon@arm.com> Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1 Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood Tested-by: Shawn Guo <shawn.guo@freescale.com> Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385 Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-06-30 09:29:12 -06:00
#include <asm/assembler.h>
#include <asm/memory.h>
/*
* Reset vector for secondary CPUs.
* This will be mapped at address 0 by SBAR register.
* We need _long_ jump to the physical address.
*/
.arm
.align 12
ENTRY(shmobile_boot_vector)
ldr r1, 1f
bx r1
ENDPROC(shmobile_boot_vector)
.align 2
.globl shmobile_boot_fn
shmobile_boot_fn:
1: .space 4
.globl shmobile_boot_size
shmobile_boot_size:
.long . - shmobile_boot_vector
/*
* Per-CPU SMP boot function/argument selection code based on MPIDR
*/
ENTRY(shmobile_smp_boot)
mrc p15, 0, r1, c0, c0, 5 @ r1 = MPIDR
and r0, r1, #0xffffff @ MPIDR_HWID_BITMASK
@ r0 = cpu_logical_map() value
mov r1, #0 @ r1 = CPU index
adr r2, 1f
ldmia r2, {r5, r6, r7}
add r5, r5, r2 @ array of per-cpu mpidr values
add r6, r6, r2 @ array of per-cpu functions
add r7, r7, r2 @ array of per-cpu arguments
shmobile_smp_boot_find_mpidr:
ldr r8, [r5, r1, lsl #2]
cmp r8, r0
bne shmobile_smp_boot_next
ldr r9, [r6, r1, lsl #2]
cmp r9, #0
bne shmobile_smp_boot_found
shmobile_smp_boot_next:
add r1, r1, #1
cmp r1, #NR_CPUS
blo shmobile_smp_boot_find_mpidr
b shmobile_smp_sleep
shmobile_smp_boot_found:
ldr r0, [r7, r1, lsl #2]
ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ ARMv6 and greater introduced a new instruction ("bx") which can be used to return from function calls. Recent CPUs perform better when the "bx lr" instruction is used rather than the "mov pc, lr" instruction, and this sequence is strongly recommended to be used by the ARM architecture manual (section A.4.1.1). We provide a new macro "ret" with all its variants for the condition code which will resolve to the appropriate instruction. Rather than doing this piecemeal, and miss some instances, change all the "mov pc" instances to use the new macro, with the exception of the "movs" instruction and the kprobes code. This allows us to detect the "mov pc, lr" case and fix it up - and also gives us the possibility of deploying this for other registers depending on the CPU selection. Reported-by: Will Deacon <will.deacon@arm.com> Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1 Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood Tested-by: Shawn Guo <shawn.guo@freescale.com> Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385 Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-06-30 09:29:12 -06:00
ret r9
ENDPROC(shmobile_smp_boot)
ENTRY(shmobile_smp_sleep)
wfi
b shmobile_smp_boot
ENDPROC(shmobile_smp_sleep)
.align 2
1: .long shmobile_smp_mpidr - .
.long shmobile_smp_fn - 1b
.long shmobile_smp_arg - 1b
.bss
.globl shmobile_smp_mpidr
shmobile_smp_mpidr:
.space NR_CPUS * 4
.globl shmobile_smp_fn
shmobile_smp_fn:
.space NR_CPUS * 4
.globl shmobile_smp_arg
shmobile_smp_arg:
.space NR_CPUS * 4