path: root/compressed/head.S

/*
 *  linux/arch/arm/boot/compressed/head.S
 *
 *  Copyright (C) 1996-2002 Russell King
 *  Copyright (C) 2004 Hyok S. Choi (MPU support)
 *
 * 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.
 */
/*
 * Debugging stuff
 *
 * Note that these macros must not contain any code which is not
 * 100% relocatable.  Any attempt to do so will result in a crash.
 * Please select one of the following when turning on debugging.
 */

	.macro  writeb, rb
	str     \rb, [r3, #0x00]        @ Transmit data register
	.endm
	
	.macro loadsp, rb, tmp
	mov \rb, #0xFE000000        @ wmt register base address
	add \rb, \rb, #0x00200000   @ uart0 base address offset
	.endm
	
	.macro	kputc,val
	mov	r0, \val
	bl	putc
	.endm
	
	.macro	kphex,val,len
	mov	r0, \val
	mov	r1, #\len
	bl	phex
	.endm

	.section ".start", #alloc, #execinstr
/*
 * sort out different calling conventions
 */
		.align
		.arm				@ Always enter in ARM state
start:
		.type	start,#function
		.rept	7
		mov	r0, r0
		.endr
   ARM(		mov	r0, r0		)
   ARM(		b	1f		)
 
		.word	0x016f2818		@ Magic numbers to help the loader
		.word	start			@ absolute load/run zImage address
		.word	_edata			@ zImage end address
 1:		mov	r7, r1			@ save architecture ID
		mov	r8, r2			@ save atags pointer


		mrs	r2, cpsr		@ turn off interrupts to
		orr	r2, r2, #0xc0		@ prevent angel from running
		msr	cpsr_c, r2

		/*
		 * some architecture specific code can be inserted
		 * by the linker here, but it should preserve r7, r8, and r9.
		 */

		.text
		ldr	r4, =zreladdr

		bl	cache_on

restart:	adr	r0, LC0
		ldmia	r0, {r1, r2, r3, r6, r10, r11, r12}
		ldr	sp, [r0, #28]

		/*
		 * We might be running at a different address.  We need
		 * to fix up various pointers.
		 */
		sub	r0, r0, r1		@ calculate the delta offset
		add	r6, r6, r0		@ _edata
		add	r10, r10, r0		@ inflated kernel size location

		/*
		 * The kernel build system appends the size of the
		 * decompressed kernel at the end of the compressed data
		 * in little-endian form.
		 */
		ldrb	r9, [r10, #0]
		ldrb	lr, [r10, #1]
		orr	r9, r9, lr, lsl #8
		ldrb	lr, [r10, #2]
		ldrb	r10, [r10, #3]
		orr	r9, r9, lr, lsl #16
		orr	r9, r9, r10, lsl #24

		/* malloc space is above the relocated stack (64k max) */
		add	sp, sp, r0
		add	r10, sp, #0x10000

/*
 * Check to see if we will overwrite ourselves.
 *   r4  = final kernel address
 *   r9  = size of decompressed image
 *   r10 = end of this image, including  bss/stack/malloc space if non XIP
 * We basically want:
 *   r4 - 16k page directory >= r10 -> OK
 *   r4 + image length <= current position (pc) -> OK
 */
		add	r10, r10, #16384
		cmp	r4, r10
		bhs	wont_overwrite
		add	r10, r4, r9
   ARM(		cmp	r10, pc		)
 THUMB(		mov	lr, pc		)
 THUMB(		cmp	r10, lr		)
		bls	wont_overwrite

/*
 * Relocate ourselves past the end of the decompressed kernel.
 *   r6  = _edata
 *   r10 = end of the decompressed kernel
 * Because we always copy ahead, we need to do it from the end and go
 * backward in case the source and destination overlap.
 */
		/*
		 * Bump to the next 256-byte boundary with the size of
		 * the relocation code added. This avoids overwriting
		 * ourself when the offset is small.
		 */
		add	r10, r10, #((reloc_code_end - restart + 256) & ~255)
		bic	r10, r10, #255

		/* Get start of code we want to copy and align it down. */
		adr	r5, restart
		bic	r5, r5, #31

		sub	r9, r6, r5		@ size to copy
		add	r9, r9, #31		@ rounded up to a multiple
		bic	r9, r9, #31		@ ... of 32 bytes
		add	r6, r9, r5
		add	r9, r9, r10

1:		ldmdb	r6!, {r0 - r3, r10 - r12, lr}
		cmp	r6, r5
		stmdb	r9!, {r0 - r3, r10 - r12, lr}
		bhi	1b

		/* Preserve offset to relocated code. */
		sub	r6, r9, r6

		/* cache_clean_flush may use the stack, so relocate it */
		add	sp, sp, r6

		bl	cache_clean_flush

		adr	r0, BSYM(restart)
		add	r0, r0, r6
		mov	pc, r0

wont_overwrite:
/*
 * If delta is zero, we are running at the address we were linked at.
 *   r0  = delta
 *   r2  = BSS start
 *   r3  = BSS end
 *   r4  = kernel execution address
 *   r7  = architecture ID
 *   r8  = atags pointer
 *   r11 = GOT start
 *   r12 = GOT end
 *   sp  = stack pointer
 */
		teq	r0, #0
		beq	not_relocated
		add	r11, r11, r0
		add	r12, r12, r0

		/*
		 * If we're running fully PIC === CONFIG_ZBOOT_ROM = n,
		 * we need to fix up pointers into the BSS region.
		 * Note that the stack pointer has already been fixed up.
		 */
		add	r2, r2, r0
		add	r3, r3, r0

		/*
		 * Relocate all entries in the GOT table.
		 */
1:		ldr	r1, [r11, #0]		@ relocate entries in the GOT
		add	r1, r1, r0		@ table.  This fixes up the
		str	r1, [r11], #4		@ C references.
		cmp	r11, r12
		blo	1b

not_relocated:	mov	r0, #0
1:		str	r0, [r2], #4		@ clear bss
		str	r0, [r2], #4
		str	r0, [r2], #4
		str	r0, [r2], #4
		cmp	r2, r3
		blo	1b

/*
 * The C runtime environment should now be setup sufficiently.
 * Set up some pointers, and start decompressing.
 *   r4  = kernel execution address
 *   r7  = architecture ID
 *   r8  = atags pointer
 */
		mov	r0, r4
		mov	r1, sp			@ malloc space above stack
		add	r2, sp, #0x10000	@ 64k max
		mov	r3, r7
		bl	decompress_kernel
		bl	cache_clean_flush
		bl	cache_off
		mov	r0, #0			@ must be zero
		mov	r1, r7			@ restore architecture number
		mov	r2, r8			@ restore atags pointer
		mov	pc, r4			@ call kernel

		.align	2
		.type	LC0, #object
LC0:		.word	LC0			@ r1
		.word	__bss_start		@ r2
		.word	_end			@ r3
		.word	_edata			@ r6
		.word	input_data_end - 4	@ r10 (inflated size location)
		.word	_got_start		@ r11
		.word	_got_end		@ ip
		.word	.L_user_stack_end	@ sp
		.size	LC0, . - LC0

		.globl	params
params:		ldr	r0, =0x10000100		@ params_phys for RPC
		mov	pc, lr
		.ltorg
		.align

/*
 * Turn on the cache.  We need to setup some page tables so that we
 * can have both the I and D caches on.
 *
 * We place the page tables 16k down from the kernel execution address,
 * and we hope that nothing else is using it.  If we're using it, we
 * will go pop!
 *
 * On entry,
 *  r4 = kernel execution address
 *  r7 = architecture number
 *  r8 = atags pointer
 * On exit,
 *  r0, r1, r2, r3, r9, r10, r12 corrupted
 * This routine must preserve:
 *  r4, r7, r8
 */
		.align	5
cache_on:	mov	r3, #8			@ cache_on function
		b	call_cache_fn

/*
 * Initialize the highest priority protection region, PR7
 * to cover all 32bit address and cacheable and bufferable.
 */
__setup_mmu:	sub	r3, r4, #16384		@ Page directory size
		bic	r3, r3, #0xff		@ Align the pointer
		bic	r3, r3, #0x3f00
/*
 * Initialise the page tables, turning on the cacheable and bufferable
 * bits for the RAM area only.
 */
		mov	r0, r3
		mov	r9, r0, lsr #18
		mov	r9, r9, lsl #18		@ start of RAM
		add	r10, r9, #0x10000000	@ a reasonable RAM size
		mov	r1, #0x12
		orr	r1, r1, #3 << 10
		add	r2, r3, #16384
1:		cmp	r1, r9			@ if virt > start of RAM

		orrhs	r1, r1, #0x0c		@ set cacheable, bufferable

		cmp	r1, r10			@ if virt > end of RAM
		bichs	r1, r1, #0x0c		@ clear cacheable, bufferable
		str	r1, [r0], #4		@ 1:1 mapping
		add	r1, r1, #1048576
		teq	r0, r2
		bne	1b
/*
 * If ever we are running from Flash, then we surely want the cache
 * to be enabled also for our execution instance...  We map 2MB of it
 * so there is no map overlap problem for up to 1 MB compressed kernel.
 * If the execution is in RAM then we would only be duplicating the above.
 */
		mov	r1, #0x1e
		orr	r1, r1, #3 << 10
		mov	r2, pc
		mov	r2, r2, lsr #20
		orr	r1, r1, r2, lsl #20
		add	r0, r3, r2, lsl #2
		str	r1, [r0], #4
		add	r1, r1, #1048576
		str	r1, [r0]
		mov	pc, lr
//ENDPROC(__setup_mmu)

__armv7_mmu_cache_on:
		mov	r12, lr

		mrc	p15, 0, r11, c0, c1, 4	@ read ID_MMFR0
		tst	r11, #0xf		@ VMSA
		blne	__setup_mmu
		mov	r0, #0
		mcr	p15, 0, r0, c7, c10, 4	@ drain write buffer
		tst	r11, #0xf		@ VMSA
		mcrne	p15, 0, r0, c8, c7, 0	@ flush I,D TLBs

		mrc	p15, 0, r0, c1, c0, 0	@ read control reg
		orr	r0, r0, #0x5000		@ I-cache enable, RR cache replacement
		orr	r0, r0, #0x003c		@ write buffer

		orrne	r0, r0, #1		@ MMU enabled
		movne	r1, #-1
		mcrne	p15, 0, r3, c2, c0, 0	@ load page table pointer
		mcrne	p15, 0, r1, c3, c0, 0	@ load domain access control

		mcr	p15, 0, r0, c1, c0, 0	@ load control register
		mrc	p15, 0, r0, c1, c0, 0	@ and read it back
		mov	r0, #0
		mcr	p15, 0, r0, c7, c5, 4	@ ISB
		mov	pc, r12

#define PROC_ENTRY_SIZE (4*5)

/*
 * Here follow the relocatable cache support functions for the
 * various processors.  This is a generic hook for locating an
 * entry and jumping to an instruction at the specified offset
 * from the start of the block.  Please note this is all position
 * independent code.
 *
 *  r1  = corrupted
 *  r2  = corrupted
 *  r3  = block offset
 *  r9  = corrupted
 *  r12 = corrupted
 */

call_cache_fn:	adr	r12, proc_types
		mrc	p15, 0, r9, c0, c0	@ get processor ID
1:		ldr	r1, [r12, #0]		@ get value
		ldr	r2, [r12, #4]		@ get mask
		eor	r1, r1, r9		@ (real ^ match)
		tst	r1, r2			@       & mask
 ARM(		addeq	pc, r12, r3		) @ call cache function
 THUMB(		addeq	r12, r3			)
 THUMB(		moveq	pc, r12			) @ call cache function
		add	r12, r12, #PROC_ENTRY_SIZE
		b	1b

/*
 * Table for cache operations.  This is basically:
 *   - CPU ID match
 *   - CPU ID mask
 *   - 'cache on' method instruction
 *   - 'cache off' method instruction
 *   - 'cache flush' method instruction
 *
 * We match an entry using: ((real_id ^ match) & mask) == 0
 *
 * Writethrough caches generally only need 'on' and 'off'
 * methods.  Writeback caches _must_ have the flush method
 * defined.
 */
		.align	2
		.type	proc_types,#object
proc_types:
		.word	0x000f0000		@ new CPU Id
		.word	0x000f0000
		W(b)	__armv7_mmu_cache_on
		W(b)	__armv7_mmu_cache_off
		W(b)	__armv7_mmu_cache_flush

		.word	0			@ unrecognised type
		.word	0
		mov	pc, lr
 THUMB(		nop				)
		mov	pc, lr
 THUMB(		nop				)
		mov	pc, lr
 THUMB(		nop				)

		.size	proc_types, . - proc_types

		/*
		 * If you get a "non-constant expression in ".if" statement"
		 * error from the assembler on this line, check that you have
		 * not accidentally written a "b" instruction where you should
		 * have written W(b).
		 */
		.if (. - proc_types) % PROC_ENTRY_SIZE != 0
		.error "The size of one or more proc_types entries is wrong."
		.endif

/*
 * Turn off the Cache and MMU.  ARMv3 does not support
 * reading the control register, but ARMv4 does.
 *
 * On exit,
 *  r0, r1, r2, r3, r9, r12 corrupted
 * This routine must preserve:
 *  r4, r7, r8
 */
		.align	5
cache_off:	mov	r3, #12			@ cache_off function
		b	call_cache_fn

__armv7_mmu_cache_off:
		mrc	p15, 0, r0, c1, c0
		bic	r0, r0, #0x000d
		mcr	p15, 0, r0, c1, c0	@ turn MMU and cache off
		mov	r12, lr
		bl	__armv7_mmu_cache_flush
		mov	r0, #0
		mcr	p15, 0, r0, c8, c7, 0	@ invalidate whole TLB
		mcr	p15, 0, r0, c7, c5, 6	@ invalidate BTC
		mcr	p15, 0, r0, c7, c10, 4	@ DSB
		mcr	p15, 0, r0, c7, c5, 4	@ ISB
		mov	pc, r12

/*
 * Clean and flush the cache to maintain consistency.
 *
 * On exit,
 *  r1, r2, r3, r9, r10, r11, r12 corrupted
 * This routine must preserve:
 *  r4, r6, r7, r8
 */
		.align	5
cache_clean_flush:
		mov	r3, #16
		b	call_cache_fn

__armv7_mmu_cache_flush:
		mrc	p15, 0, r10, c0, c1, 5	@ read ID_MMFR1
		tst	r10, #0xf << 16		@ hierarchical cache (ARMv7)
		mov	r10, #0
		beq	hierarchical
		mcr	p15, 0, r10, c7, c14, 0	@ clean+invalidate D
		b	iflush
hierarchical:
		mcr	p15, 0, r10, c7, c10, 5	@ DMB
		stmfd	sp!, {r0-r7, r9-r11}
		mrc	p15, 1, r0, c0, c0, 1	@ read clidr
		ands	r3, r0, #0x7000000	@ extract loc from clidr
		mov	r3, r3, lsr #23		@ left align loc bit field
		beq	finished		@ if loc is 0, then no need to clean
		mov	r10, #0			@ start clean at cache level 0
loop1:
		add	r2, r10, r10, lsr #1	@ work out 3x current cache level
		mov	r1, r0, lsr r2		@ extract cache type bits from clidr
		and	r1, r1, #7		@ mask of the bits for current cache only
		cmp	r1, #2			@ see what cache we have at this level
		blt	skip			@ skip if no cache, or just i-cache
		mcr	p15, 2, r10, c0, c0, 0	@ select current cache level in cssr
		mcr	p15, 0, r10, c7, c5, 4	@ isb to sych the new cssr&csidr
		mrc	p15, 1, r1, c0, c0, 0	@ read the new csidr
		and	r2, r1, #7		@ extract the length of the cache lines
		add	r2, r2, #4		@ add 4 (line length offset)
		ldr	r4, =0x3ff
		ands	r4, r4, r1, lsr #3	@ find maximum number on the way size
		clz	r5, r4			@ find bit position of way size increment
		ldr	r7, =0x7fff
		ands	r7, r7, r1, lsr #13	@ extract max number of the index size
loop2:
		mov	r9, r4			@ create working copy of max way size
loop3:
 ARM(		orr	r11, r10, r9, lsl r5	) @ factor way and cache number into r11
 ARM(		orr	r11, r11, r7, lsl r2	) @ factor index number into r11
 THUMB(		lsl	r6, r9, r5		)
 THUMB(		orr	r11, r10, r6		) @ factor way and cache number into r11
 THUMB(		lsl	r6, r7, r2		)
 THUMB(		orr	r11, r11, r6		) @ factor index number into r11
		mcr	p15, 0, r11, c7, c14, 2	@ clean & invalidate by set/way
		subs	r9, r9, #1		@ decrement the way
		bge	loop3
		subs	r7, r7, #1		@ decrement the index
		bge	loop2
skip:
		add	r10, r10, #2		@ increment cache number
		cmp	r3, r10
		bgt	loop1
finished:
		ldmfd	sp!, {r0-r7, r9-r11}
		mov	r10, #0			@ swith back to cache level 0
		mcr	p15, 2, r10, c0, c0, 0	@ select current cache level in cssr
iflush:
		mcr	p15, 0, r10, c7, c10, 4	@ DSB
		mcr	p15, 0, r10, c7, c5, 0	@ invalidate I+BTB
		mcr	p15, 0, r10, c7, c10, 4	@ DSB
		mcr	p15, 0, r10, c7, c5, 4	@ ISB
		mov	pc, lr

/*
 * Various debugging routines for printing hex characters and
 * memory, which again must be relocatable.
 */
#ifdef DEBUG
		.align	2
		.type	phexbuf,#object
phexbuf:	.space	12
		.size	phexbuf, . - phexbuf

@ phex corrupts {r0, r1, r2, r3}
phex:		adr	r3, phexbuf
		mov	r2, #0
		strb	r2, [r3, r1]
1:		subs	r1, r1, #1
		movmi	r0, r3
		bmi	puts
		and	r2, r0, #15
		mov	r0, r0, lsr #4
		cmp	r2, #10
		addge	r2, r2, #7
		add	r2, r2, #'0'
		strb	r2, [r3, r1]
		b	1b

@ puts corrupts {r0, r1, r2, r3}
puts:		loadsp	r3, r1
1:		ldrb	r2, [r0], #1
		teq	r2, #0
		moveq	pc, lr
/*2:		writeb	r2, r3*/
2:		writeb	r2 
		mov	r1, #0x00020000
3:		subs	r1, r1, #1
		bne	3b
		teq	r2, #'\n'
		moveq	r2, #'\r'
		beq	2b
		teq	r0, #0
		bne	1b
		mov	pc, lr
@ putc corrupts {r0, r1, r2, r3}
putc:
		mov	r2, r0
		mov	r0, #0
		loadsp	r3, r1
		b	2b

@ memdump corrupts {r0, r1, r2, r3, r10, r11, r12, lr}
memdump:	mov	r12, r0
		mov	r10, lr
		mov	r11, #0
2:		mov	r0, r11, lsl #2
		add	r0, r0, r12
		mov	r1, #8
		bl	phex
		mov	r0, #':'
		bl	putc
1:		mov	r0, #' '
		bl	putc
		ldr	r0, [r12, r11, lsl #2]
		mov	r1, #8
		bl	phex
		and	r0, r11, #7
		teq	r0, #3
		moveq	r0, #' '
		bleq	putc
		and	r0, r11, #7
		add	r11, r11, #1
		teq	r0, #7
		bne	1b
		mov	r0, #'\n'
		bl	putc
		cmp	r11, #64
		blt	2b
		mov	pc, r10
#endif

		.ltorg
reloc_code_end:

		.align
		.section ".stack", "aw", %nobits
.L_user_stack:	.space	4096
.L_user_stack_end: