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bc7dea00a9
Some ARM cores are not capable to run in ARM mode (e.g. Cortex-M3). So obviously these cannot enter the kernel in ARM mode. Make an exception for them and let them enter in THUMB mode. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Message-Id: 1358162123-30113-1-git-send-email-u.kleine-koenig@pengutronix.de Acked-by: Nicolas Pitre <nico@linaro.org>
105 lines
2.4 KiB
ArmAsm
105 lines
2.4 KiB
ArmAsm
/*
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* linux/arch/arm/kernel/head-nommu.S
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*
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* Copyright (C) 1994-2002 Russell King
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* Copyright (C) 2003-2006 Hyok S. Choi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Common kernel startup code (non-paged MM)
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*
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*/
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#include <linux/linkage.h>
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#include <linux/init.h>
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#include <asm/assembler.h>
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#include <asm/ptrace.h>
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#include <asm/asm-offsets.h>
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#include <asm/cp15.h>
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#include <asm/thread_info.h>
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/*
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* Kernel startup entry point.
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* ---------------------------
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*
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* This is normally called from the decompressor code. The requirements
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* are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
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* r1 = machine nr.
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*
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* See linux/arch/arm/tools/mach-types for the complete list of machine
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* numbers for r1.
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*
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*/
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__HEAD
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#ifdef CONFIG_CPU_THUMBONLY
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.thumb
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ENTRY(stext)
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#else
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.arm
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ENTRY(stext)
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THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM.
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THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
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THUMB( .thumb ) @ switch to Thumb now.
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THUMB(1: )
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#endif
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setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
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@ and irqs disabled
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#ifndef CONFIG_CPU_CP15
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ldr r9, =CONFIG_PROCESSOR_ID
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#else
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mrc p15, 0, r9, c0, c0 @ get processor id
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#endif
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bl __lookup_processor_type @ r5=procinfo r9=cpuid
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movs r10, r5 @ invalid processor (r5=0)?
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beq __error_p @ yes, error 'p'
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adr lr, BSYM(__after_proc_init) @ return (PIC) address
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ARM( add pc, r10, #PROCINFO_INITFUNC )
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THUMB( add r12, r10, #PROCINFO_INITFUNC )
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THUMB( mov pc, r12 )
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ENDPROC(stext)
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/*
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* Set the Control Register and Read the process ID.
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*/
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__after_proc_init:
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#ifdef CONFIG_CPU_CP15
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/*
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* CP15 system control register value returned in r0 from
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* the CPU init function.
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*/
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#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
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orr r0, r0, #CR_A
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#else
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bic r0, r0, #CR_A
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#endif
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#ifdef CONFIG_CPU_DCACHE_DISABLE
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bic r0, r0, #CR_C
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#endif
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#ifdef CONFIG_CPU_BPREDICT_DISABLE
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bic r0, r0, #CR_Z
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#endif
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#ifdef CONFIG_CPU_ICACHE_DISABLE
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bic r0, r0, #CR_I
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#endif
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#ifdef CONFIG_CPU_HIGH_VECTOR
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orr r0, r0, #CR_V
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#else
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bic r0, r0, #CR_V
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#endif
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mcr p15, 0, r0, c1, c0, 0 @ write control reg
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#endif /* CONFIG_CPU_CP15 */
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b __mmap_switched @ clear the BSS and jump
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@ to start_kernel
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ENDPROC(__after_proc_init)
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.ltorg
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#include "head-common.S"
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