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| Current File : //sys/i386/i386/locore.s |
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)locore.s 7.3 (Berkeley) 5/13/91
* $FreeBSD: release/9.1.0/sys/i386/i386/locore.s 213455 2010-10-05 17:06:51Z alc $
*
* originally from: locore.s, by William F. Jolitz
*
* Substantially rewritten by David Greenman, Rod Grimes,
* Bruce Evans, Wolfgang Solfrank, Poul-Henning Kamp
* and many others.
*/
#include "opt_bootp.h"
#include "opt_compat.h"
#include "opt_nfsroot.h"
#include "opt_pmap.h"
#include <sys/syscall.h>
#include <sys/reboot.h>
#include <machine/asmacros.h>
#include <machine/cputypes.h>
#include <machine/psl.h>
#include <machine/pmap.h>
#include <machine/specialreg.h>
#include "assym.s"
/*
* XXX
*
* Note: This version greatly munged to avoid various assembler errors
* that may be fixed in newer versions of gas. Perhaps newer versions
* will have more pleasant appearance.
*/
/*
* PTmap is recursive pagemap at top of virtual address space.
* Within PTmap, the page directory can be found (third indirection).
*/
.globl PTmap,PTD,PTDpde
.set PTmap,(PTDPTDI << PDRSHIFT)
.set PTD,PTmap + (PTDPTDI * PAGE_SIZE)
.set PTDpde,PTD + (PTDPTDI * PDESIZE)
/*
* Compiled KERNBASE location and the kernel load address
*/
.globl kernbase
.set kernbase,KERNBASE
.globl kernload
.set kernload,KERNLOAD
/*
* Globals
*/
.data
ALIGN_DATA /* just to be sure */
.space 0x2000 /* space for tmpstk - temporary stack */
tmpstk:
.globl bootinfo
bootinfo: .space BOOTINFO_SIZE /* bootinfo that we can handle */
.globl KERNend
KERNend: .long 0 /* phys addr end of kernel (just after bss) */
physfree: .long 0 /* phys addr of next free page */
.globl IdlePTD
IdlePTD: .long 0 /* phys addr of kernel PTD */
#ifdef PAE
.globl IdlePDPT
IdlePDPT: .long 0 /* phys addr of kernel PDPT */
#endif
.globl KPTmap
KPTmap: .long 0 /* address of kernel page tables */
.globl KPTphys
KPTphys: .long 0 /* phys addr of kernel page tables */
.globl proc0kstack
proc0kstack: .long 0 /* address of proc 0 kstack space */
p0kpa: .long 0 /* phys addr of proc0's STACK */
vm86phystk: .long 0 /* PA of vm86/bios stack */
.globl vm86paddr, vm86pa
vm86paddr: .long 0 /* address of vm86 region */
vm86pa: .long 0 /* phys addr of vm86 region */
#ifdef PC98
.globl pc98_system_parameter
pc98_system_parameter:
.space 0x240
#endif
/**********************************************************************
*
* Some handy macros
*
*/
#define R(foo) ((foo)-KERNBASE)
#define ALLOCPAGES(foo) \
movl R(physfree), %esi ; \
movl $((foo)*PAGE_SIZE), %eax ; \
addl %esi, %eax ; \
movl %eax, R(physfree) ; \
movl %esi, %edi ; \
movl $((foo)*PAGE_SIZE),%ecx ; \
xorl %eax,%eax ; \
cld ; \
rep ; \
stosb
/*
* fillkpt
* eax = page frame address
* ebx = index into page table
* ecx = how many pages to map
* base = base address of page dir/table
* prot = protection bits
*/
#define fillkpt(base, prot) \
shll $PTESHIFT,%ebx ; \
addl base,%ebx ; \
orl $PG_V,%eax ; \
orl prot,%eax ; \
1: movl %eax,(%ebx) ; \
addl $PAGE_SIZE,%eax ; /* increment physical address */ \
addl $PTESIZE,%ebx ; /* next pte */ \
loop 1b
/*
* fillkptphys(prot)
* eax = physical address
* ecx = how many pages to map
* prot = protection bits
*/
#define fillkptphys(prot) \
movl %eax, %ebx ; \
shrl $PAGE_SHIFT, %ebx ; \
fillkpt(R(KPTphys), prot)
.text
/**********************************************************************
*
* This is where the bootblocks start us, set the ball rolling...
*
*/
NON_GPROF_ENTRY(btext)
#ifdef PC98
/* save SYSTEM PARAMETER for resume (NS/T or other) */
movl $0xa1400,%esi
movl $R(pc98_system_parameter),%edi
movl $0x0240,%ecx
cld
rep
movsb
#else /* IBM-PC */
/* Tell the bios to warmboot next time */
movw $0x1234,0x472
#endif /* PC98 */
/* Set up a real frame in case the double return in newboot is executed. */
pushl %ebp
movl %esp, %ebp
/* Don't trust what the BIOS gives for eflags. */
pushl $PSL_KERNEL
popfl
/*
* Don't trust what the BIOS gives for %fs and %gs. Trust the bootstrap
* to set %cs, %ds, %es and %ss.
*/
mov %ds, %ax
mov %ax, %fs
mov %ax, %gs
/*
* Clear the bss. Not all boot programs do it, and it is our job anyway.
*
* XXX we don't check that there is memory for our bss and page tables
* before using it.
*
* Note: we must be careful to not overwrite an active gdt or idt. They
* inactive from now until we switch to new ones, since we don't load any
* more segment registers or permit interrupts until after the switch.
*/
movl $R(end),%ecx
movl $R(edata),%edi
subl %edi,%ecx
xorl %eax,%eax
cld
rep
stosb
call recover_bootinfo
/* Get onto a stack that we can trust. */
/*
* XXX this step is delayed in case recover_bootinfo needs to return via
* the old stack, but it need not be, since recover_bootinfo actually
* returns via the old frame.
*/
movl $R(tmpstk),%esp
#ifdef PC98
/* pc98_machine_type & M_EPSON_PC98 */
testb $0x02,R(pc98_system_parameter)+220
jz 3f
/* epson_machine_id <= 0x0b */
cmpb $0x0b,R(pc98_system_parameter)+224
ja 3f
/* count up memory */
movl $0x100000,%eax /* next, talley remaining memory */
movl $0xFFF-0x100,%ecx
1: movl 0(%eax),%ebx /* save location to check */
movl $0xa55a5aa5,0(%eax) /* write test pattern */
cmpl $0xa55a5aa5,0(%eax) /* does not check yet for rollover */
jne 2f
movl %ebx,0(%eax) /* restore memory */
addl $PAGE_SIZE,%eax
loop 1b
2: subl $0x100000,%eax
shrl $17,%eax
movb %al,R(pc98_system_parameter)+1
3:
movw R(pc98_system_parameter+0x86),%ax
movw %ax,R(cpu_id)
#endif
call identify_cpu
call create_pagetables
/*
* If the CPU has support for VME, turn it on.
*/
testl $CPUID_VME, R(cpu_feature)
jz 1f
movl %cr4, %eax
orl $CR4_VME, %eax
movl %eax, %cr4
1:
/* Now enable paging */
#ifdef PAE
movl R(IdlePDPT), %eax
movl %eax, %cr3
movl %cr4, %eax
orl $CR4_PAE, %eax
movl %eax, %cr4
#else
movl R(IdlePTD), %eax
movl %eax,%cr3 /* load ptd addr into mmu */
#endif
movl %cr0,%eax /* get control word */
orl $CR0_PE|CR0_PG,%eax /* enable paging */
movl %eax,%cr0 /* and let's page NOW! */
pushl $begin /* jump to high virtualized address */
ret
/* now running relocated at KERNBASE where the system is linked to run */
begin:
/* set up bootstrap stack */
movl proc0kstack,%eax /* location of in-kernel stack */
/* bootstrap stack end location */
leal (KSTACK_PAGES*PAGE_SIZE-PCB_SIZE)(%eax),%esp
xorl %ebp,%ebp /* mark end of frames */
#ifdef PAE
movl IdlePDPT,%esi
#else
movl IdlePTD,%esi
#endif
movl %esi,(KSTACK_PAGES*PAGE_SIZE-PCB_SIZE+PCB_CR3)(%eax)
pushl physfree /* value of first for init386(first) */
call init386 /* wire 386 chip for unix operation */
/*
* Clean up the stack in a way that db_numargs() understands, so
* that backtraces in ddb don't underrun the stack. Traps for
* inaccessible memory are more fatal than usual this early.
*/
addl $4,%esp
call mi_startup /* autoconfiguration, mountroot etc */
/* NOTREACHED */
addl $0,%esp /* for db_numargs() again */
/*
* Signal trampoline, copied to top of user stack
*/
NON_GPROF_ENTRY(sigcode)
calll *SIGF_HANDLER(%esp)
leal SIGF_UC(%esp),%eax /* get ucontext */
pushl %eax
testl $PSL_VM,UC_EFLAGS(%eax)
jne 1f
mov UC_GS(%eax),%gs /* restore %gs */
1:
movl $SYS_sigreturn,%eax
pushl %eax /* junk to fake return addr. */
int $0x80 /* enter kernel with args */
/* on stack */
1:
jmp 1b
#ifdef COMPAT_FREEBSD4
ALIGN_TEXT
freebsd4_sigcode:
calll *SIGF_HANDLER(%esp)
leal SIGF_UC4(%esp),%eax /* get ucontext */
pushl %eax
testl $PSL_VM,UC4_EFLAGS(%eax)
jne 1f
mov UC4_GS(%eax),%gs /* restore %gs */
1:
movl $344,%eax /* 4.x SYS_sigreturn */
pushl %eax /* junk to fake return addr. */
int $0x80 /* enter kernel with args */
/* on stack */
1:
jmp 1b
#endif
#ifdef COMPAT_43
ALIGN_TEXT
osigcode:
call *SIGF_HANDLER(%esp) /* call signal handler */
lea SIGF_SC(%esp),%eax /* get sigcontext */
pushl %eax
testl $PSL_VM,SC_PS(%eax)
jne 9f
mov SC_GS(%eax),%gs /* restore %gs */
9:
movl $103,%eax /* 3.x SYS_sigreturn */
pushl %eax /* junk to fake return addr. */
int $0x80 /* enter kernel with args */
0: jmp 0b
#endif /* COMPAT_43 */
ALIGN_TEXT
esigcode:
.data
.globl szsigcode
szsigcode:
.long esigcode-sigcode
#ifdef COMPAT_FREEBSD4
.globl szfreebsd4_sigcode
szfreebsd4_sigcode:
.long esigcode-freebsd4_sigcode
#endif
#ifdef COMPAT_43
.globl szosigcode
szosigcode:
.long esigcode-osigcode
#endif
.text
/**********************************************************************
*
* Recover the bootinfo passed to us from the boot program
*
*/
recover_bootinfo:
/*
* This code is called in different ways depending on what loaded
* and started the kernel. This is used to detect how we get the
* arguments from the other code and what we do with them.
*
* Old disk boot blocks:
* (*btext)(howto, bootdev, cyloffset, esym);
* [return address == 0, and can NOT be returned to]
* [cyloffset was not supported by the FreeBSD boot code
* and always passed in as 0]
* [esym is also known as total in the boot code, and
* was never properly supported by the FreeBSD boot code]
*
* Old diskless netboot code:
* (*btext)(0,0,0,0,&nfsdiskless,0,0,0);
* [return address != 0, and can NOT be returned to]
* If we are being booted by this code it will NOT work,
* so we are just going to halt if we find this case.
*
* New uniform boot code:
* (*btext)(howto, bootdev, 0, 0, 0, &bootinfo)
* [return address != 0, and can be returned to]
*
* There may seem to be a lot of wasted arguments in here, but
* that is so the newer boot code can still load very old kernels
* and old boot code can load new kernels.
*/
/*
* The old style disk boot blocks fake a frame on the stack and
* did an lret to get here. The frame on the stack has a return
* address of 0.
*/
cmpl $0,4(%ebp)
je olddiskboot
/*
* We have some form of return address, so this is either the
* old diskless netboot code, or the new uniform code. That can
* be detected by looking at the 5th argument, if it is 0
* we are being booted by the new uniform boot code.
*/
cmpl $0,24(%ebp)
je newboot
/*
* Seems we have been loaded by the old diskless boot code, we
* don't stand a chance of running as the diskless structure
* changed considerably between the two, so just halt.
*/
hlt
/*
* We have been loaded by the new uniform boot code.
* Let's check the bootinfo version, and if we do not understand
* it we return to the loader with a status of 1 to indicate this error
*/
newboot:
movl 28(%ebp),%ebx /* &bootinfo.version */
movl BI_VERSION(%ebx),%eax
cmpl $1,%eax /* We only understand version 1 */
je 1f
movl $1,%eax /* Return status */
leave
/*
* XXX this returns to our caller's caller (as is required) since
* we didn't set up a frame and our caller did.
*/
ret
1:
/*
* If we have a kernelname copy it in
*/
movl BI_KERNELNAME(%ebx),%esi
cmpl $0,%esi
je 2f /* No kernelname */
movl $MAXPATHLEN,%ecx /* Brute force!!! */
movl $R(kernelname),%edi
cmpb $'/',(%esi) /* Make sure it starts with a slash */
je 1f
movb $'/',(%edi)
incl %edi
decl %ecx
1:
cld
rep
movsb
2:
/*
* Determine the size of the boot loader's copy of the bootinfo
* struct. This is impossible to do properly because old versions
* of the struct don't contain a size field and there are 2 old
* versions with the same version number.
*/
movl $BI_ENDCOMMON,%ecx /* prepare for sizeless version */
testl $RB_BOOTINFO,8(%ebp) /* bi_size (and bootinfo) valid? */
je got_bi_size /* no, sizeless version */
movl BI_SIZE(%ebx),%ecx
got_bi_size:
/*
* Copy the common part of the bootinfo struct
*/
movl %ebx,%esi
movl $R(bootinfo),%edi
cmpl $BOOTINFO_SIZE,%ecx
jbe got_common_bi_size
movl $BOOTINFO_SIZE,%ecx
got_common_bi_size:
cld
rep
movsb
#ifdef NFS_ROOT
#ifndef BOOTP_NFSV3
/*
* If we have a nfs_diskless structure copy it in
*/
movl BI_NFS_DISKLESS(%ebx),%esi
cmpl $0,%esi
je olddiskboot
movl $R(nfs_diskless),%edi
movl $NFSDISKLESS_SIZE,%ecx
cld
rep
movsb
movl $R(nfs_diskless_valid),%edi
movl $1,(%edi)
#endif
#endif
/*
* The old style disk boot.
* (*btext)(howto, bootdev, cyloffset, esym);
* Note that the newer boot code just falls into here to pick
* up howto and bootdev, cyloffset and esym are no longer used
*/
olddiskboot:
movl 8(%ebp),%eax
movl %eax,R(boothowto)
movl 12(%ebp),%eax
movl %eax,R(bootdev)
ret
/**********************************************************************
*
* Identify the CPU and initialize anything special about it
*
*/
identify_cpu:
/* Try to toggle alignment check flag; does not exist on 386. */
pushfl
popl %eax
movl %eax,%ecx
orl $PSL_AC,%eax
pushl %eax
popfl
pushfl
popl %eax
xorl %ecx,%eax
andl $PSL_AC,%eax
pushl %ecx
popfl
testl %eax,%eax
jnz try486
/* NexGen CPU does not have aligment check flag. */
pushfl
movl $0x5555, %eax
xorl %edx, %edx
movl $2, %ecx
clc
divl %ecx
jz trynexgen
popfl
movl $CPU_386,R(cpu)
jmp 3f
trynexgen:
popfl
movl $CPU_NX586,R(cpu)
movl $0x4778654e,R(cpu_vendor) # store vendor string
movl $0x72446e65,R(cpu_vendor+4)
movl $0x6e657669,R(cpu_vendor+8)
movl $0,R(cpu_vendor+12)
jmp 3f
try486: /* Try to toggle identification flag; does not exist on early 486s. */
pushfl
popl %eax
movl %eax,%ecx
xorl $PSL_ID,%eax
pushl %eax
popfl
pushfl
popl %eax
xorl %ecx,%eax
andl $PSL_ID,%eax
pushl %ecx
popfl
testl %eax,%eax
jnz trycpuid
movl $CPU_486,R(cpu)
/*
* Check Cyrix CPU
* Cyrix CPUs do not change the undefined flags following
* execution of the divide instruction which divides 5 by 2.
*
* Note: CPUID is enabled on M2, so it passes another way.
*/
pushfl
movl $0x5555, %eax
xorl %edx, %edx
movl $2, %ecx
clc
divl %ecx
jnc trycyrix
popfl
jmp 3f /* You may use Intel CPU. */
trycyrix:
popfl
/*
* IBM Bluelighting CPU also doesn't change the undefined flags.
* Because IBM doesn't disclose the information for Bluelighting
* CPU, we couldn't distinguish it from Cyrix's (including IBM
* brand of Cyrix CPUs).
*/
movl $0x69727943,R(cpu_vendor) # store vendor string
movl $0x736e4978,R(cpu_vendor+4)
movl $0x64616574,R(cpu_vendor+8)
jmp 3f
trycpuid: /* Use the `cpuid' instruction. */
xorl %eax,%eax
cpuid # cpuid 0
movl %eax,R(cpu_high) # highest capability
movl %ebx,R(cpu_vendor) # store vendor string
movl %edx,R(cpu_vendor+4)
movl %ecx,R(cpu_vendor+8)
movb $0,R(cpu_vendor+12)
movl $1,%eax
cpuid # cpuid 1
movl %eax,R(cpu_id) # store cpu_id
movl %ebx,R(cpu_procinfo) # store cpu_procinfo
movl %edx,R(cpu_feature) # store cpu_feature
movl %ecx,R(cpu_feature2) # store cpu_feature2
rorl $8,%eax # extract family type
andl $15,%eax
cmpl $5,%eax
jae 1f
/* less than Pentium; must be 486 */
movl $CPU_486,R(cpu)
jmp 3f
1:
/* a Pentium? */
cmpl $5,%eax
jne 2f
movl $CPU_586,R(cpu)
jmp 3f
2:
/* Greater than Pentium...call it a Pentium Pro */
movl $CPU_686,R(cpu)
3:
ret
/**********************************************************************
*
* Create the first page directory and its page tables.
*
*/
create_pagetables:
/* Find end of kernel image (rounded up to a page boundary). */
movl $R(_end),%esi
/* Include symbols, if any. */
movl R(bootinfo+BI_ESYMTAB),%edi
testl %edi,%edi
je over_symalloc
movl %edi,%esi
movl $KERNBASE,%edi
addl %edi,R(bootinfo+BI_SYMTAB)
addl %edi,R(bootinfo+BI_ESYMTAB)
over_symalloc:
/* If we are told where the end of the kernel space is, believe it. */
movl R(bootinfo+BI_KERNEND),%edi
testl %edi,%edi
je no_kernend
movl %edi,%esi
no_kernend:
addl $PDRMASK,%esi /* Play conservative for now, and */
andl $~PDRMASK,%esi /* ... wrap to next 4M. */
movl %esi,R(KERNend) /* save end of kernel */
movl %esi,R(physfree) /* next free page is at end of kernel */
/* Allocate Kernel Page Tables */
ALLOCPAGES(NKPT)
movl %esi,R(KPTphys)
addl $(KERNBASE-(KPTDI<<(PDRSHIFT-PAGE_SHIFT+PTESHIFT))),%esi
movl %esi,R(KPTmap)
/* Allocate Page Table Directory */
#ifdef PAE
/* XXX only need 32 bytes (easier for now) */
ALLOCPAGES(1)
movl %esi,R(IdlePDPT)
#endif
ALLOCPAGES(NPGPTD)
movl %esi,R(IdlePTD)
/* Allocate KSTACK */
ALLOCPAGES(KSTACK_PAGES)
movl %esi,R(p0kpa)
addl $KERNBASE, %esi
movl %esi, R(proc0kstack)
ALLOCPAGES(1) /* vm86/bios stack */
movl %esi,R(vm86phystk)
ALLOCPAGES(3) /* pgtable + ext + IOPAGES */
movl %esi,R(vm86pa)
addl $KERNBASE, %esi
movl %esi, R(vm86paddr)
/*
* Enable PSE and PGE.
*/
#ifndef DISABLE_PSE
testl $CPUID_PSE, R(cpu_feature)
jz 1f
movl $PG_PS, R(pseflag)
movl %cr4, %eax
orl $CR4_PSE, %eax
movl %eax, %cr4
1:
#endif
#ifndef DISABLE_PG_G
testl $CPUID_PGE, R(cpu_feature)
jz 2f
movl $PG_G, R(pgeflag)
movl %cr4, %eax
orl $CR4_PGE, %eax
movl %eax, %cr4
2:
#endif
/*
* Initialize page table pages mapping physical address zero through the
* end of the kernel. All of the page table entries allow read and write
* access. Write access to the first physical page is required by bios32
* calls, and write access to the first 1 MB of physical memory is required
* by ACPI for implementing suspend and resume. We do this even
* if we've enabled PSE above, we'll just switch the corresponding kernel
* PDEs before we turn on paging.
*
* XXX: We waste some pages here in the PSE case! DON'T BLINDLY REMOVE
* THIS! SMP needs the page table to be there to map the kernel P==V.
*/
xorl %eax, %eax
movl R(KERNend),%ecx
shrl $PAGE_SHIFT,%ecx
fillkptphys($PG_RW)
/* Map page table pages. */
movl R(KPTphys),%eax
movl $NKPT,%ecx
fillkptphys($PG_RW)
/* Map page directory. */
#ifdef PAE
movl R(IdlePDPT), %eax
movl $1, %ecx
fillkptphys($PG_RW)
#endif
movl R(IdlePTD), %eax
movl $NPGPTD, %ecx
fillkptphys($PG_RW)
/* Map proc0's KSTACK in the physical way ... */
movl R(p0kpa), %eax
movl $(KSTACK_PAGES), %ecx
fillkptphys($PG_RW)
/* Map ISA hole */
movl $ISA_HOLE_START, %eax
movl $ISA_HOLE_LENGTH>>PAGE_SHIFT, %ecx
fillkptphys($PG_RW)
/* Map space for the vm86 region */
movl R(vm86phystk), %eax
movl $4, %ecx
fillkptphys($PG_RW)
/* Map page 0 into the vm86 page table */
movl $0, %eax
movl $0, %ebx
movl $1, %ecx
fillkpt(R(vm86pa), $PG_RW|PG_U)
/* ...likewise for the ISA hole */
movl $ISA_HOLE_START, %eax
movl $ISA_HOLE_START>>PAGE_SHIFT, %ebx
movl $ISA_HOLE_LENGTH>>PAGE_SHIFT, %ecx
fillkpt(R(vm86pa), $PG_RW|PG_U)
/*
* Create an identity mapping for low physical memory, including the kernel.
* The part of this mapping that covers the first 1 MB of physical memory
* becomes a permanent part of the kernel's address space. The rest of this
* mapping is destroyed in pmap_bootstrap(). Ordinarily, the same page table
* pages are shared by the identity mapping and the kernel's native mapping.
* However, the permanent identity mapping cannot contain PG_G mappings.
* Thus, if the kernel is loaded within the permanent identity mapping, that
* page table page must be duplicated and not shared.
*
* N.B. Due to errata concerning large pages and physical address zero,
* a PG_PS mapping is not used.
*/
movl R(KPTphys), %eax
xorl %ebx, %ebx
movl $NKPT, %ecx
fillkpt(R(IdlePTD), $PG_RW)
#if KERNLOAD < (1 << PDRSHIFT)
testl $PG_G, R(pgeflag)
jz 1f
ALLOCPAGES(1)
movl %esi, %edi
movl R(IdlePTD), %eax
movl (%eax), %esi
movl %edi, (%eax)
movl $PAGE_SIZE, %ecx
cld
rep
movsb
1:
#endif
/*
* For the non-PSE case, install PDEs for PTs covering the KVA.
* For the PSE case, do the same, but clobber the ones corresponding
* to the kernel (from btext to KERNend) with 4M (2M for PAE) ('PS')
* PDEs immediately after.
*/
movl R(KPTphys), %eax
movl $KPTDI, %ebx
movl $NKPT, %ecx
fillkpt(R(IdlePTD), $PG_RW)
cmpl $0,R(pseflag)
je done_pde
movl R(KERNend), %ecx
movl $KERNLOAD, %eax
subl %eax, %ecx
shrl $PDRSHIFT, %ecx
movl $(KPTDI+(KERNLOAD/(1 << PDRSHIFT))), %ebx
shll $PDESHIFT, %ebx
addl R(IdlePTD), %ebx
orl $(PG_V|PG_RW|PG_PS), %eax
1: movl %eax, (%ebx)
addl $(1 << PDRSHIFT), %eax
addl $PDESIZE, %ebx
loop 1b
done_pde:
/* install a pde recursively mapping page directory as a page table */
movl R(IdlePTD), %eax
movl $PTDPTDI, %ebx
movl $NPGPTD,%ecx
fillkpt(R(IdlePTD), $PG_RW)
#ifdef PAE
movl R(IdlePTD), %eax
xorl %ebx, %ebx
movl $NPGPTD, %ecx
fillkpt(R(IdlePDPT), $0x0)
#endif
ret