head.s

优龙2410linux2.6.8内核源代码

/* $Id: head.S,v 1.87 2002/02/09 19:49:31 davem Exp $
 * head.S: Initial boot code for the Sparc64 port of Linux.
 *
 * Copyright (C) 1996,1997 David S. Miller ([e-mail])
 * Copyright (C) 1996 David Sitsky ([e-mail])
 * Copyright (C) 1997,1998 Jakub Jelinek ([e-mail])
 * Copyright (C) 1997 Miguel de Icaza ([e-mail])
 */

#include <linux/config.h>
#include <linux/version.h>
#include <linux/errno.h>
#include <asm/thread_info.h>
#include <asm/asi.h>
#include <asm/pstate.h>
#include <asm/ptrace.h>
#include <asm/spitfire.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/errno.h>
#include <asm/signal.h>
#include <asm/processor.h>
#include <asm/lsu.h>
#include <asm/dcr.h>
#include <asm/dcu.h>
#include <asm/head.h>
#include <asm/ttable.h>
	
/* This section from from _start to sparc64_boot_end should fit into
 * 0x0000.0000.0040.4000 to 0x0000.0000.0040.8000 and will be sharing space
 * with bootup_user_stack, which is from 0x0000.0000.0040.4000 to
 * 0x0000.0000.0040.6000 and empty_bad_page, which is from
 * 0x0000.0000.0040.6000 to 0x0000.0000.0040.8000. 
 */

	.text
	.globl	start, _start, stext, _stext
_start:
start:
_stext:
stext:
bootup_user_stack:
! 0x0000000000404000
	b	sparc64_boot
	 flushw					/* Flush register file.      */

/* This stuff has to be in sync with SILO and other potential boot loaders
 * Fields should be kept upward compatible and whenever any change is made,
 * HdrS version should be incremented.
 */
        .global root_flags, ram_flags, root_dev
        .global sparc_ramdisk_image, sparc_ramdisk_size

        .ascii  "HdrS"
        .word   LINUX_VERSION_CODE

	/* History:
	 *
	 * 0x0300 : Supports being located at other than 0x4000
	 * 0x0202 : Supports kernel params string
	 * 0x0201 : Supports reboot_command
	 */
	.half   0x0300          /* HdrS version */

root_flags:
        .half   1
root_dev:
        .half   0
ram_flags:
        .half   0
sparc_ramdisk_image:
        .word   0
sparc_ramdisk_size:
        .word   0
        .xword  reboot_command
	.xword	bootstr_info
	.word	_end

	/* We must be careful, 32-bit OpenBOOT will get confused if it
	 * tries to save away a register window to a 64-bit kernel
	 * stack address.  Flush all windows, disable interrupts,
	 * remap if necessary, jump onto kernel trap table, then kernel
	 * stack, or else we die.
	 *
	 * PROM entry point is on %o4
	 */
sparc64_boot:
	BRANCH_IF_CHEETAH_BASE(g1,g5,cheetah_boot)
	BRANCH_IF_CHEETAH_PLUS_OR_FOLLOWON(g1,g5,cheetah_plus_boot)
	ba,pt	%xcc, spitfire_boot
	 nop

cheetah_plus_boot:
	/* Preserve OBP chosen DCU and DCR register settings.  */
	ba,pt	%xcc, cheetah_generic_boot
	 nop

cheetah_boot:
	mov	DCR_BPE | DCR_RPE | DCR_SI | DCR_IFPOE | DCR_MS, %g1
	wr	%g1, %asr18

	sethi	%uhi(DCU_ME|DCU_RE|DCU_HPE|DCU_SPE|DCU_SL|DCU_WE), %g5
	or	%g5, %ulo(DCU_ME|DCU_RE|DCU_HPE|DCU_SPE|DCU_SL|DCU_WE), %g5
	sllx	%g5, 32, %g5
	or	%g5, DCU_DM | DCU_IM | DCU_DC | DCU_IC, %g5
	stxa	%g5, [%g0] ASI_DCU_CONTROL_REG
	membar	#Sync

cheetah_generic_boot:
	mov	TSB_EXTENSION_P, %g3
	stxa	%g0, [%g3] ASI_DMMU
	stxa	%g0, [%g3] ASI_IMMU
	membar	#Sync

	mov	TSB_EXTENSION_S, %g3
	stxa	%g0, [%g3] ASI_DMMU
	membar	#Sync

	mov	TSB_EXTENSION_N, %g3
	stxa	%g0, [%g3] ASI_DMMU
	stxa	%g0, [%g3] ASI_IMMU
	membar	#Sync

	wrpr    %g0, (PSTATE_PRIV|PSTATE_PEF|PSTATE_IE), %pstate
	wr	%g0, 0, %fprs

	/* Just like for Spitfire, we probe itlb-2 for a mapping which
	 * matches our current %pc.  We take the physical address in
	 * that mapping and use it to make our own.
	 */

	/* %g5 holds the tlb data */
        sethi   %uhi(_PAGE_VALID | _PAGE_SZ4MB), %g5
        sllx    %g5, 32, %g5
        or      %g5, (_PAGE_CP | _PAGE_CV | _PAGE_P | _PAGE_L | _PAGE_W | _PAGE_G), %g5

	/* Put PADDR tlb data mask into %g3. */
	sethi	%uhi(_PAGE_PADDR), %g3
	or	%g3, %ulo(_PAGE_PADDR), %g3
	sllx	%g3, 32, %g3
	sethi	%hi(_PAGE_PADDR), %g7
	or	%g7, %lo(_PAGE_PADDR), %g7
	or	%g3, %g7, %g3

	set	2 << 16, %l0		/* TLB entry walker. */
	set	0x1fff, %l2		/* Page mask. */
	rd	%pc, %l3
	andn	%l3, %l2, %g2		/* vaddr comparator */

1:	ldxa	[%l0] ASI_ITLB_TAG_READ, %g1
	membar	#Sync
	andn	%g1, %l2, %g1
	cmp	%g1, %g2
	be,pn	%xcc, cheetah_got_tlbentry
	 nop
	and	%l0, (127 << 3), %g1
	cmp	%g1, (127 << 3)
	blu,pt	%xcc, 1b
	 add	%l0, (1 << 3), %l0

	/* Search the small TLB.  OBP never maps us like that but
	 * newer SILO can.
	 */
	clr	%l0

1:	ldxa	[%l0] ASI_ITLB_TAG_READ, %g1
	membar	#Sync
	andn	%g1, %l2, %g1
	cmp	%g1, %g2
	be,pn	%xcc, cheetah_got_tlbentry
	 nop
	cmp	%l0, (15 << 3)
	blu,pt	%xcc, 1b
	 add	%l0, (1 << 3), %l0

	/* BUG() if we get here... */
	ta	0x5

cheetah_got_tlbentry:
	ldxa	[%l0] ASI_ITLB_DATA_ACCESS, %g0
	ldxa	[%l0] ASI_ITLB_DATA_ACCESS, %g1
	membar	#Sync
	and	%g1, %g3, %g1
	set	0x5fff, %l0
	andn	%g1, %l0, %g1
	or	%g5, %g1, %g5

	/* Clear out any KERNBASE area entries. */
	set	2 << 16, %l0
	sethi	%hi(KERNBASE), %g3
	sethi	%hi(KERNBASE<<1), %g7
	mov	TLB_TAG_ACCESS, %l7

	/* First, check ITLB */
1:	ldxa	[%l0] ASI_ITLB_TAG_READ, %g1
	membar	#Sync
	andn	%g1, %l2, %g1
	cmp	%g1, %g3
	blu,pn	%xcc, 2f
	 cmp	%g1, %g7
	bgeu,pn	%xcc, 2f
	 nop
	stxa	%g0, [%l7] ASI_IMMU
	membar	#Sync
	stxa	%g0, [%l0] ASI_ITLB_DATA_ACCESS
	membar	#Sync

2:	and	%l0, (127 << 3), %g1
	cmp	%g1, (127 << 3)
	blu,pt	%xcc, 1b
	 add	%l0, (1 << 3), %l0

	/* Next, check DTLB */
	set	2 << 16, %l0
1:	ldxa	[%l0] ASI_DTLB_TAG_READ, %g1
	membar	#Sync
	andn	%g1, %l2, %g1
	cmp	%g1, %g3
	blu,pn	%xcc, 2f
	 cmp	%g1, %g7
	bgeu,pn	%xcc, 2f
	 nop
	stxa	%g0, [%l7] ASI_DMMU
	membar	#Sync
	stxa	%g0, [%l0] ASI_DTLB_DATA_ACCESS
	membar	#Sync
	
2:	and	%l0, (511 << 3), %g1
	cmp	%g1, (511 << 3)
	blu,pt	%xcc, 1b
	 add	%l0, (1 << 3), %l0

	/* On Cheetah+, have to check second DTLB.  */
	BRANCH_IF_CHEETAH_PLUS_OR_FOLLOWON(g1,l0,2f)
	ba,pt	%xcc, 9f
	 nop

2:	set	3 << 16, %l0
1:	ldxa	[%l0] ASI_DTLB_TAG_READ, %g1
	membar	#Sync
	andn	%g1, %l2, %g1
	cmp	%g1, %g3
	blu,pn	%xcc, 2f
	 cmp	%g1, %g7
	bgeu,pn	%xcc, 2f
	 nop
	stxa	%g0, [%l7] ASI_DMMU
	membar	#Sync
	stxa	%g0, [%l0] ASI_DTLB_DATA_ACCESS
	membar	#Sync
	
2:	and	%l0, (511 << 3), %g1
	cmp	%g1, (511 << 3)
	blu,pt	%xcc, 1b
	 add	%l0, (1 << 3), %l0

9:

	/* Now lock the TTE we created into ITLB-0 and DTLB-0,
	 * entry 15 (and maybe 14 too).
	 */
	sethi	%hi(KERNBASE), %g3
	set	(0 << 16) | (15 << 3), %g7
	stxa	%g3, [%l7] ASI_DMMU
	membar	#Sync
	stxa	%g5, [%g7] ASI_DTLB_DATA_ACCESS
	membar	#Sync
	stxa	%g3, [%l7] ASI_IMMU
	membar	#Sync
	stxa	%g5, [%g7] ASI_ITLB_DATA_ACCESS
	membar	#Sync
	flush	%g3
	membar	#Sync
	sethi	%hi(_end), %g3			/* Check for bigkernel case */
	or	%g3, %lo(_end), %g3
	srl	%g3, 23, %g3			/* Check if _end > 8M */
	brz,pt	%g3, 1f
	 sethi	%hi(KERNBASE), %g3		/* Restore for fixup code below */
	sethi	%hi(0x400000), %g3
	or	%g3, %lo(0x400000), %g3
	add	%g5, %g3, %g5			/* New tte data */
	andn	%g5, (_PAGE_G), %g5
	sethi	%hi(KERNBASE+0x400000), %g3
	or	%g3, %lo(KERNBASE+0x400000), %g3
	set	(0 << 16) | (14 << 3), %g7
	stxa	%g3, [%l7] ASI_DMMU
	membar	#Sync
	stxa	%g5, [%g7] ASI_DTLB_DATA_ACCESS
	membar	#Sync
	stxa	%g3, [%l7] ASI_IMMU
	membar	#Sync
	stxa	%g5, [%g7] ASI_ITLB_DATA_ACCESS
	membar	#Sync
	flush	%g3
	membar	#Sync
	sethi	%hi(KERNBASE), %g3		/* Restore for fixup code below */
	ba,pt	%xcc, 1f
	 nop

1:	set	sun4u_init, %g2
	jmpl    %g2 + %g0, %g0
	 nop

spitfire_boot:
	/* Typically PROM has already enabled both MMU's and both on-chip
	 * caches, but we do it here anyway just to be paranoid.
	 */
	mov	(LSU_CONTROL_IC|LSU_CONTROL_DC|LSU_CONTROL_IM|LSU_CONTROL_DM), %g1
	stxa	%g1, [%g0] ASI_LSU_CONTROL
	membar	#Sync

	/*
	 * Make sure we are in privileged mode, have address masking,
         * using the ordinary globals and have enabled floating
         * point.
	 *
	 * Again, typically PROM has left %pil at 13 or similar, and
	 * (PSTATE_PRIV | PSTATE_PEF | PSTATE_IE) in %pstate.
         */
	wrpr    %g0, (PSTATE_PRIV|PSTATE_PEF|PSTATE_IE), %pstate
	wr	%g0, 0, %fprs

spitfire_create_mappings:
	/* %g5 holds the tlb data */
        sethi   %uhi(_PAGE_VALID | _PAGE_SZ4MB), %g5
        sllx    %g5, 32, %g5
        or      %g5, (_PAGE_CP | _PAGE_CV | _PAGE_P | _PAGE_L | _PAGE_W | _PAGE_G), %g5

	/* Base of physical memory cannot reliably be assumed to be
	 * at 0x0!  Figure out where it happens to be. -DaveM
	 */

	/* Put PADDR tlb data mask into %g3. */
	sethi	%uhi(_PAGE_PADDR_SF), %g3
	or	%g3, %ulo(_PAGE_PADDR_SF), %g3
	sllx	%g3, 32, %g3
	sethi	%hi(_PAGE_PADDR_SF), %g7
	or	%g7, %lo(_PAGE_PADDR_SF), %g7
	or	%g3, %g7, %g3

	/* Walk through entire ITLB, looking for entry which maps
	 * our %pc currently, stick PADDR from there into %g5 tlb data.
	 */
	clr	%l0			/* TLB entry walker. */
	set	0x1fff, %l2		/* Page mask. */
	rd	%pc, %l3
	andn	%l3, %l2, %g2		/* vaddr comparator */
1:
	/* Yes, the nops seem to be necessary for now, don't ask me why. -DaveM */
	ldxa	[%l0] ASI_ITLB_TAG_READ, %g1
	nop
	nop
	nop
	andn	%g1, %l2, %g1		/* Get vaddr */
	cmp	%g1, %g2
	be,a,pn	%xcc, spitfire_got_tlbentry
	 ldxa	[%l0] ASI_ITLB_DATA_ACCESS, %g1
	cmp	%l0, (63 << 3)
	blu,pt	%xcc, 1b
	 add	%l0, (1 << 3), %l0

	/* BUG() if we get here... */
	ta	0x5

spitfire_got_tlbentry:
	/* Nops here again, perhaps Cheetah/Blackbird are better behaved... */
	nop
	nop
	nop
	and	%g1, %g3, %g1		/* Mask to just get paddr bits.       */
	set	0x5fff, %l3		/* Mask offset to get phys base.      */