arch/arm/kernel/head-common.S - maze/linux - Git at Google

 /*
  *  linux/arch/arm/kernel/head-common.S
  *
  *  Copyright (C) 1994-2002 Russell King
  *  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.
  *
  */

 #define ATAG_CORE 0x54410001
 #define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
 #define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)

 	.align	2
 	.type	__switch_data, %object
 __switch_data:
 	.long	__mmap_switched
 	.long	__data_loc			@ r4
 	.long	_data				@ r5
 	.long	__bss_start			@ r6
 	.long	_end				@ r7
 	.long	processor_id			@ r4
 	.long	__machine_arch_type		@ r5
 	.long	__atags_pointer			@ r6
 	.long	cr_alignment			@ r7
 	.long	init_thread_union + THREAD_START_SP @ sp

 /*
  * The following fragment of code is executed with the MMU on in MMU mode,
  * and uses absolute addresses; this is not position independent.
  *
  *  r0  = cp#15 control register
  *  r1  = machine ID
  *  r2  = atags pointer
  *  r9  = processor ID
  */
 __mmap_switched:
 	adr	r3, __switch_data + 4

 	ldmia	r3!, {r4, r5, r6, r7}
 	cmp	r4, r5				@ Copy data segment if needed
 1:	cmpne	r5, r6
 	ldrne	fp, [r4], #4
 	strne	fp, [r5], #4
 	bne	1b

 	mov	fp, #0				@ Clear BSS (and zero fp)
 1:	cmp	r6, r7
 	strcc	fp, [r6],#4
 	bcc	1b

  ARM(	ldmia	r3, {r4, r5, r6, r7, sp})
  THUMB(	ldmia	r3, {r4, r5, r6, r7}	)
  THUMB(	ldr	sp, [r3, #16]		)
 	str	r9, [r4]			@ Save processor ID
 	str	r1, [r5]			@ Save machine type
 	str	r2, [r6]			@ Save atags pointer
 	bic	r4, r0, #CR_A			@ Clear 'A' bit
 	stmia	r7, {r0, r4}			@ Save control register values
 	b	start_kernel
 ENDPROC(__mmap_switched)

 /*
  * Exception handling.  Something went wrong and we can't proceed.  We
  * ought to tell the user, but since we don't have any guarantee that
  * we're even running on the right architecture, we do virtually nothing.
  *
  * If CONFIG_DEBUG_LL is set we try to print out something about the error
  * and hope for the best (useful if bootloader fails to pass a proper
  * machine ID for example).
  */
 __error_p:
 #ifdef CONFIG_DEBUG_LL
 	adr	r0, str_p1
 	bl	printascii
 	mov	r0, r9
 	bl	printhex8
 	adr	r0, str_p2
 	bl	printascii
 	b	__error
 str_p1:	.asciz	"\nError: unrecognized/unsupported processor variant (0x"
 str_p2:	.asciz	").\n"
 	.align
 #endif
 ENDPROC(__error_p)

 __error_a:
 #ifdef CONFIG_DEBUG_LL
 	mov	r4, r1				@ preserve machine ID
 	adr	r0, str_a1
 	bl	printascii
 	mov	r0, r4
 	bl	printhex8
 	adr	r0, str_a2
 	bl	printascii
 	adr	r3, 4f
 	ldmia	r3, {r4, r5, r6}		@ get machine desc list
 	sub	r4, r3, r4			@ get offset between virt&phys
 	add	r5, r5, r4			@ convert virt addresses to
 	add	r6, r6, r4			@ physical address space
 1:	ldr	r0, [r5, #MACHINFO_TYPE]	@ get machine type
 	bl	printhex8
 	mov	r0, #'\t'
 	bl	printch
 	ldr     r0, [r5, #MACHINFO_NAME]	@ get machine name
 	add	r0, r0, r4
 	bl	printascii
 	mov	r0, #'\n'
 	bl	printch
 	add	r5, r5, #SIZEOF_MACHINE_DESC	@ next machine_desc
 	cmp	r5, r6
 	blo	1b
 	adr	r0, str_a3
 	bl	printascii
 	b	__error
 ENDPROC(__error_a)

 str_a1:	.asciz	"\nError: unrecognized/unsupported machine ID (r1 = 0x"
 str_a2:	.asciz	").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
 str_a3:	.asciz	"\nPlease check your kernel config and/or bootloader.\n"
 	.align
 #endif

 __error:
 #ifdef CONFIG_ARCH_RPC
 /*
  * Turn the screen red on a error - RiscPC only.
  */
 	mov	r0, #0x02000000
 	mov	r3, #0x11
 	orr	r3, r3, r3, lsl #8
 	orr	r3, r3, r3, lsl #16
 	str	r3, [r0], #4
 	str	r3, [r0], #4
 	str	r3, [r0], #4
 	str	r3, [r0], #4
 #endif
 1:	mov	r0, r0
 	b	1b
 ENDPROC(__error)


 /*
  * Read processor ID register (CP#15, CR0), and look up in the linker-built
  * supported processor list.  Note that we can't use the absolute addresses
  * for the __proc_info lists since we aren't running with the MMU on
  * (and therefore, we are not in the correct address space).  We have to
  * calculate the offset.
  *
  *	r9 = cpuid
  * Returns:
  *	r3, r4, r6 corrupted
  *	r5 = proc_info pointer in physical address space
  *	r9 = cpuid (preserved)
  */
 __lookup_processor_type:
 	adr	r3, 3f
 	ldmia	r3, {r5 - r7}
 	add	r3, r3, #8
 	sub	r3, r3, r7			@ get offset between virt&phys
 	add	r5, r5, r3			@ convert virt addresses to
 	add	r6, r6, r3			@ physical address space
 1:	ldmia	r5, {r3, r4}			@ value, mask
 	and	r4, r4, r9			@ mask wanted bits
 	teq	r3, r4
 	beq	2f
 	add	r5, r5, #PROC_INFO_SZ		@ sizeof(proc_info_list)
 	cmp	r5, r6
 	blo	1b
 	mov	r5, #0				@ unknown processor
 2:	mov	pc, lr
 ENDPROC(__lookup_processor_type)

 /*
  * This provides a C-API version of the above function.
  */
 ENTRY(lookup_processor_type)
 	stmfd	sp!, {r4 - r7, r9, lr}
 	mov	r9, r0
 	bl	__lookup_processor_type
 	mov	r0, r5
 	ldmfd	sp!, {r4 - r7, r9, pc}
 ENDPROC(lookup_processor_type)

 /*
  * Look in <asm/procinfo.h> and arch/arm/kernel/arch.[ch] for
  * more information about the __proc_info and __arch_info structures.
  */
 	.align	2
 3:	.long	__proc_info_begin
 	.long	__proc_info_end
 4:	.long	.
 	.long	__arch_info_begin
 	.long	__arch_info_end

 /*
  * Lookup machine architecture in the linker-build list of architectures.
  * Note that we can't use the absolute addresses for the __arch_info
  * lists since we aren't running with the MMU on (and therefore, we are
  * not in the correct address space).  We have to calculate the offset.
  *
  *  r1 = machine architecture number
  * Returns:
  *  r3, r4, r6 corrupted
  *  r5 = mach_info pointer in physical address space
  */
 __lookup_machine_type:
 	adr	r3, 4b
 	ldmia	r3, {r4, r5, r6}
 	sub	r3, r3, r4			@ get offset between virt&phys
 	add	r5, r5, r3			@ convert virt addresses to
 	add	r6, r6, r3			@ physical address space
 1:	ldr	r3, [r5, #MACHINFO_TYPE]	@ get machine type
 	teq	r3, r1				@ matches loader number?
 	beq	2f				@ found
 	add	r5, r5, #SIZEOF_MACHINE_DESC	@ next machine_desc
 	cmp	r5, r6
 	blo	1b
 	mov	r5, #0				@ unknown machine
 2:	mov	pc, lr
 ENDPROC(__lookup_machine_type)

 /*
  * This provides a C-API version of the above function.
  */
 ENTRY(lookup_machine_type)
 	stmfd	sp!, {r4 - r6, lr}
 	mov	r1, r0
 	bl	__lookup_machine_type
 	mov	r0, r5
 	ldmfd	sp!, {r4 - r6, pc}
 ENDPROC(lookup_machine_type)

 /* Determine validity of the r2 atags pointer.  The heuristic requires
  * that the pointer be aligned, in the first 16k of physical RAM and
  * that the ATAG_CORE marker is first and present.  Future revisions
  * of this function may be more lenient with the physical address and
  * may also be able to move the ATAGS block if necessary.
  *
  * r8  = machinfo
  *
  * Returns:
  *  r2 either valid atags pointer, or zero
  *  r5, r6 corrupted
  */
 __vet_atags:
 	tst	r2, #0x3			@ aligned?
 	bne	1f

 	ldr	r5, [r2, #0]			@ is first tag ATAG_CORE?
 	cmp	r5, #ATAG_CORE_SIZE
 	cmpne	r5, #ATAG_CORE_SIZE_EMPTY
 	bne	1f
 	ldr	r5, [r2, #4]
 	ldr	r6, =ATAG_CORE
 	cmp	r5, r6
 	bne	1f

 	mov	pc, lr				@ atag pointer is ok

 1:	mov	r2, #0
 	mov	pc, lr
 ENDPROC(__vet_atags)
	/*
	* linux/arch/arm/kernel/head-common.S
	*
	* Copyright (C) 1994-2002 Russell King
	* 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.
	*
	*/

	#define ATAG_CORE 0x54410001
	#define ATAG_CORE_SIZE ((24 + 34) >> 2)
	#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)

	.align 2
	.type __switch_data, %object
	__switch_data:
	.long __mmap_switched
	.long __data_loc @ r4
	.long _data @ r5
	.long __bss_start @ r6
	.long _end @ r7
	.long processor_id @ r4
	.long __machine_arch_type @ r5
	.long __atags_pointer @ r6
	.long cr_alignment @ r7
	.long init_thread_union + THREAD_START_SP @ sp

	/*
	* The following fragment of code is executed with the MMU on in MMU mode,
	* and uses absolute addresses; this is not position independent.
	*
	* r0 = cp#15 control register
	* r1 = machine ID
	* r2 = atags pointer
	* r9 = processor ID
	*/
	__mmap_switched:
	adr r3, __switch_data + 4

	ldmia r3!, {r4, r5, r6, r7}
	cmp r4, r5 @ Copy data segment if needed
	1: cmpne r5, r6
	ldrne fp, [r4], #4
	strne fp, [r5], #4
	bne 1b

	mov fp, #0 @ Clear BSS (and zero fp)
	1: cmp r6, r7
	strcc fp, [r6],#4
	bcc 1b

	ARM( ldmia r3, {r4, r5, r6, r7, sp})
	THUMB( ldmia r3, {r4, r5, r6, r7} )
	THUMB( ldr sp, [r3, #16] )
	str r9, [r4] @ Save processor ID
	str r1, [r5] @ Save machine type
	str r2, [r6] @ Save atags pointer
	bic r4, r0, #CR_A @ Clear 'A' bit
	stmia r7, {r0, r4} @ Save control register values
	b start_kernel
	ENDPROC(__mmap_switched)

	/*
	* Exception handling. Something went wrong and we can't proceed. We
	* ought to tell the user, but since we don't have any guarantee that
	* we're even running on the right architecture, we do virtually nothing.
	*
	* If CONFIG_DEBUG_LL is set we try to print out something about the error
	* and hope for the best (useful if bootloader fails to pass a proper
	* machine ID for example).
	*/
	__error_p:
	#ifdef CONFIG_DEBUG_LL
	adr r0, str_p1
	bl printascii
	mov r0, r9
	bl printhex8
	adr r0, str_p2
	bl printascii
	b __error
	str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x"
	str_p2: .asciz ").\n"
	.align
	#endif
	ENDPROC(__error_p)

	__error_a:
	#ifdef CONFIG_DEBUG_LL
	mov r4, r1 @ preserve machine ID
	adr r0, str_a1
	bl printascii
	mov r0, r4
	bl printhex8
	adr r0, str_a2
	bl printascii
	adr r3, 4f
	ldmia r3, {r4, r5, r6} @ get machine desc list
	sub r4, r3, r4 @ get offset between virt&phys
	add r5, r5, r4 @ convert virt addresses to
	add r6, r6, r4 @ physical address space
	1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type
	bl printhex8
	mov r0, #'\t'
	bl printch
	ldr r0, [r5, #MACHINFO_NAME] @ get machine name
	add r0, r0, r4
	bl printascii
	mov r0, #'\n'
	bl printch
	add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
	cmp r5, r6
	blo 1b
	adr r0, str_a3
	bl printascii
	b __error
	ENDPROC(__error_a)

	str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x"
	str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
	str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n"
	.align
	#endif

	__error:
	#ifdef CONFIG_ARCH_RPC
	/*
	* Turn the screen red on a error - RiscPC only.
	*/
	mov r0, #0x02000000
	mov r3, #0x11
	orr r3, r3, r3, lsl #8
	orr r3, r3, r3, lsl #16
	str r3, [r0], #4
	str r3, [r0], #4
	str r3, [r0], #4
	str r3, [r0], #4
	#endif
	1: mov r0, r0
	b 1b
	ENDPROC(__error)


	/*
	* Read processor ID register (CP#15, CR0), and look up in the linker-built
	* supported processor list. Note that we can't use the absolute addresses
	* for the __proc_info lists since we aren't running with the MMU on
	* (and therefore, we are not in the correct address space). We have to
	* calculate the offset.
	*
	* r9 = cpuid
	* Returns:
	* r3, r4, r6 corrupted
	* r5 = proc_info pointer in physical address space
	* r9 = cpuid (preserved)
	*/
	__lookup_processor_type:
	adr r3, 3f
	ldmia r3, {r5 - r7}
	add r3, r3, #8
	sub r3, r3, r7 @ get offset between virt&phys
	add r5, r5, r3 @ convert virt addresses to
	add r6, r6, r3 @ physical address space
	1: ldmia r5, {r3, r4} @ value, mask
	and r4, r4, r9 @ mask wanted bits
	teq r3, r4
	beq 2f
	add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
	cmp r5, r6
	blo 1b
	mov r5, #0 @ unknown processor
	2: mov pc, lr
	ENDPROC(__lookup_processor_type)

	/*
	* This provides a C-API version of the above function.
	*/
	ENTRY(lookup_processor_type)
	stmfd sp!, {r4 - r7, r9, lr}
	mov r9, r0
	bl __lookup_processor_type
	mov r0, r5
	ldmfd sp!, {r4 - r7, r9, pc}
	ENDPROC(lookup_processor_type)

	/*
	* Look in <asm/procinfo.h> and arch/arm/kernel/arch.[ch] for
	* more information about the __proc_info and __arch_info structures.
	*/
	.align 2
	3: .long __proc_info_begin
	.long __proc_info_end
	4: .long .
	.long __arch_info_begin
	.long __arch_info_end

	/*
	* Lookup machine architecture in the linker-build list of architectures.
	* Note that we can't use the absolute addresses for the __arch_info
	* lists since we aren't running with the MMU on (and therefore, we are
	* not in the correct address space). We have to calculate the offset.
	*
	* r1 = machine architecture number
	* Returns:
	* r3, r4, r6 corrupted
	* r5 = mach_info pointer in physical address space
	*/
	__lookup_machine_type:
	adr r3, 4b
	ldmia r3, {r4, r5, r6}
	sub r3, r3, r4 @ get offset between virt&phys
	add r5, r5, r3 @ convert virt addresses to
	add r6, r6, r3 @ physical address space
	1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type
	teq r3, r1 @ matches loader number?
	beq 2f @ found
	add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
	cmp r5, r6
	blo 1b
	mov r5, #0 @ unknown machine
	2: mov pc, lr
	ENDPROC(__lookup_machine_type)

	/*
	* This provides a C-API version of the above function.
	*/
	ENTRY(lookup_machine_type)
	stmfd sp!, {r4 - r6, lr}
	mov r1, r0
	bl __lookup_machine_type
	mov r0, r5
	ldmfd sp!, {r4 - r6, pc}
	ENDPROC(lookup_machine_type)

	/* Determine validity of the r2 atags pointer. The heuristic requires
	* that the pointer be aligned, in the first 16k of physical RAM and
	* that the ATAG_CORE marker is first and present. Future revisions
	* of this function may be more lenient with the physical address and
	* may also be able to move the ATAGS block if necessary.
	*
	* r8 = machinfo
	*
	* Returns:
	* r2 either valid atags pointer, or zero
	* r5, r6 corrupted
	*/
	__vet_atags:
	tst r2, #0x3 @ aligned?
	bne 1f

	ldr r5, [r2, #0] @ is first tag ATAG_CORE?
	cmp r5, #ATAG_CORE_SIZE
	cmpne r5, #ATAG_CORE_SIZE_EMPTY
	bne 1f
	ldr r5, [r2, #4]
	ldr r6, =ATAG_CORE
	cmp r5, r6
	bne 1f

	mov pc, lr @ atag pointer is ok

	1: mov r2, #0
	mov pc, lr
	ENDPROC(__vet_atags)