2 * Copyright (c) 1990 The Regents of the University of California.
5 * This code is derived from software contributed to Berkeley by
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * from: @(#)locore.s 7.3 (Berkeley) 5/13/91
37 * $FreeBSD: src/sys/i386/i386/locore.s,v 1.132.2.10 2003/02/03 20:54:49 jhb Exp $
38 * $DragonFly: src/sys/platform/pc32/i386/locore.s,v 1.10 2005/02/27 10:57:24 swildner Exp $
40 * originally from: locore.s, by William F. Jolitz
42 * Substantially rewritten by David Greenman, Rod Grimes,
43 * Bruce Evans, Wolfgang Solfrank, Poul-Henning Kamp
47 #include "opt_bootp.h"
48 #include "opt_nfsroot.h"
50 #include <sys/syscall.h>
51 #include <sys/reboot.h>
53 #include <machine/asmacros.h>
54 #include <machine/cputypes.h>
55 #include <machine/psl.h>
56 #include <machine/pmap.h>
57 #include <machine/specialreg.h>
64 * Note: This version greatly munged to avoid various assembler errors
65 * that may be fixed in newer versions of gas. Perhaps newer versions
66 * will have more pleasant appearance.
70 * PTmap is recursive pagemap at top of virtual address space.
71 * Within PTmap, the page directory can be found (third indirection).
73 .globl PTmap,PTD,PTDpde
74 .set PTmap,(PTDPTDI << PDRSHIFT)
75 .set PTD,PTmap + (PTDPTDI * PAGE_SIZE)
76 .set PTDpde,PTD + (PTDPTDI * PDESIZE)
79 * APTmap, APTD is the alternate recursive pagemap.
80 * It's used when modifying another process's page tables.
82 .globl APTmap,APTD,APTDpde
83 .set APTmap,APTDPTDI << PDRSHIFT
84 .set APTD,APTmap + (APTDPTDI * PAGE_SIZE)
85 .set APTDpde,PTD + (APTDPTDI * PDESIZE)
88 * Compiled KERNBASE location
91 .set kernbase,KERNBASE
97 ALIGN_DATA /* just to be sure */
100 .space 0x2000 /* space for tmpstk - temporary stack */
103 .globl boothowto,bootdev
105 .globl cpu,cpu_vendor,cpu_id,bootinfo
106 .globl cpu_high, cpu_feature, cpu_procinfo
108 cpu: .long 0 /* are we 386, 386sx, or 486 */
109 cpu_id: .long 0 /* stepping ID */
110 cpu_high: .long 0 /* highest arg to CPUID */
111 cpu_feature: .long 0 /* features */
112 cpu_procinfo: .long 0 /* brand index / HTT info */
113 cpu_vendor: .space 20 /* CPU origin code */
114 bootinfo: .space BOOTINFO_SIZE /* bootinfo buffer space */
116 KERNend: .long 0 /* phys addr end of kernel (just after bss) */
117 physfree: .long 0 /* phys addr of next free page */
120 cpu0pp: .long 0 /* phys addr cpu0 private pg */
121 cpu0prvpage: .long 0 /* relocated version */
122 cpu0idlestk: .long 0 /* stack for the idle thread */
125 SMPptpa: .long 0 /* phys addr SMP page table */
126 SMPpt: .long 0 /* relocated version */
129 IdlePTD: .long 0 /* phys addr of kernel PTD */
132 KPTphys: .long 0 /* PA of kernel page tables */
135 proc0paddr: .long 0 /* VA of proc 0 address space */
136 p0upa: .long 0 /* PA of proc0's UPAGES */
138 vm86phystk: .long 0 /* PA of vm86/bios stack */
140 .globl vm86paddr, vm86pa
141 vm86paddr: .long 0 /* address of vm86 region */
142 vm86pa: .long 0 /* phys addr of vm86 region */
145 .globl bdb_exists /* BDE debugger is present */
149 /**********************************************************************
155 #define R(foo) ((foo)-KERNBASE)
157 #define ALLOCPAGES(foo) \
158 movl R(physfree), %esi ; \
159 movl $((foo)*PAGE_SIZE), %eax ; \
161 movl %eax, R(physfree) ; \
163 movl $((foo)*PAGE_SIZE),%ecx ; \
171 * eax = page frame address
172 * ebx = index into page table
173 * ecx = how many pages to map
174 * base = base address of page dir/table
175 * prot = protection bits
177 #define fillkpt(base, prot) \
182 1: movl %eax,(%ebx) ; \
183 addl $PAGE_SIZE,%eax ; /* increment physical address */ \
184 addl $4,%ebx ; /* next pte */ \
189 * eax = physical address
190 * ecx = how many pages to map
191 * prot = protection bits
193 #define fillkptphys(prot) \
195 shrl $PAGE_SHIFT, %ebx ; \
196 fillkpt(R(KPTphys), prot)
199 /**********************************************************************
201 * This is where the bootblocks start us, set the ball rolling...
204 NON_GPROF_ENTRY(btext)
207 #ifdef BIOS_STEALS_3K
208 cmpl $0x0375c339,0x95504
210 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */
213 movb $1,R(bdb_exists)
216 /* Tell the bios to warmboot next time */
219 /* Set up a real frame in case the double return in newboot is executed. */
223 /* Don't trust what the BIOS gives for eflags. */
228 * Don't trust what the BIOS gives for %fs and %gs. Trust the bootstrap
229 * to set %cs, %ds, %es and %ss.
236 * Clear the bss. Not all boot programs do it, and it is our job anyway.
238 * XXX we don't check that there is memory for our bss and page tables
241 * Note: we must be careful to not overwrite an active gdt or idt. They
242 * inactive from now until we switch to new ones, since we don't load any
243 * more segment registers or permit interrupts until after the switch.
253 call recover_bootinfo
255 /* Get onto a stack that we can trust. */
257 * XXX this step is delayed in case recover_bootinfo needs to return via
258 * the old stack, but it need not be, since recover_bootinfo actually
259 * returns via the old frame.
261 movl $R(.tmpstk),%esp
265 call create_pagetables
268 * If the CPU has support for VME, turn it on.
270 testl $CPUID_VME, R(cpu_feature)
279 * Adjust as much as possible for paging before enabling paging so that the
280 * adjustments can be traced.
282 call bdb_prepare_paging
285 /* Now enable paging */
286 movl R(IdlePTD), %eax
287 movl %eax,%cr3 /* load ptd addr into mmu */
288 movl %cr0,%eax /* get control word */
289 orl $CR0_PE|CR0_PG,%eax /* enable paging */
290 movl %eax,%cr0 /* and let's page NOW! */
295 * Complete the adjustments for paging so that we can keep tracing through
296 * initi386() after the low (physical) addresses for the gdt and idt become
299 call bdb_commit_paging
302 pushl $begin /* jump to high virtualized address */
305 /* now running relocated at KERNBASE where the system is linked to run */
309 * set up the bootstrap stack. The pcb sits at the end of the
312 /* set up bootstrap stack */
313 movl proc0paddr,%esp /* location of in-kernel pages */
314 addl $UPAGES*PAGE_SIZE-PCB_SIZE,%esp
315 xorl %eax,%eax /* mark end of frames */
317 /*movl proc0paddr,%eax*/
319 movl %esi,PCB_CR3(%esp)
321 testl $CPUID_PGE, R(cpu_feature)
329 pushl %esi /* value of first for init386(first) */
331 call init386 /* wire 386 chip for unix operation */
334 call mi_startup /* autoconfiguration, mountroot etc */
336 hlt /* never returns to here */
339 * Signal trampoline, copied to top of user stack
341 NON_GPROF_ENTRY(sigcode)
342 call *SIGF_HANDLER(%esp) /* call signal handler */
343 lea SIGF_UC(%esp),%eax /* get ucontext_t */
345 testl $PSL_VM,UC_EFLAGS(%eax)
347 movl UC_GS(%eax),%gs /* restore %gs */
349 movl $SYS_sigreturn,%eax
350 pushl %eax /* junk to fake return addr. */
351 int $0x80 /* enter kernel with args */
360 .long esigcode - sigcode
363 /**********************************************************************
365 * Recover the bootinfo passed to us from the boot program
370 * This code is called in different ways depending on what loaded
371 * and started the kernel. This is used to detect how we get the
372 * arguments from the other code and what we do with them.
374 * Old disk boot blocks:
375 * (*btext)(howto, bootdev, cyloffset, esym);
376 * [return address == 0, and can NOT be returned to]
377 * [cyloffset was not supported by the FreeBSD boot code
378 * and always passed in as 0]
379 * [esym is also known as total in the boot code, and
380 * was never properly supported by the FreeBSD boot code]
382 * Old diskless netboot code:
383 * (*btext)(0,0,0,0,&nfsdiskless,0,0,0);
384 * [return address != 0, and can NOT be returned to]
385 * If we are being booted by this code it will NOT work,
386 * so we are just going to halt if we find this case.
388 * New uniform boot code:
389 * (*btext)(howto, bootdev, 0, 0, 0, &bootinfo)
390 * [return address != 0, and can be returned to]
392 * There may seem to be a lot of wasted arguments in here, but
393 * that is so the newer boot code can still load very old kernels
394 * and old boot code can load new kernels.
398 * The old style disk boot blocks fake a frame on the stack and
399 * did an lret to get here. The frame on the stack has a return
406 * We have some form of return address, so this is either the
407 * old diskless netboot code, or the new uniform code. That can
408 * be detected by looking at the 5th argument, if it is 0
409 * we are being booted by the new uniform boot code.
415 * Seems we have been loaded by the old diskless boot code, we
416 * don't stand a chance of running as the diskless structure
417 * changed considerably between the two, so just halt.
422 * We have been loaded by the new uniform boot code.
423 * Let's check the bootinfo version, and if we do not understand
424 * it we return to the loader with a status of 1 to indicate this error
427 movl 28(%ebp),%ebx /* &bootinfo.version */
428 movl BI_VERSION(%ebx),%eax
429 cmpl $1,%eax /* We only understand version 1 */
431 movl $1,%eax /* Return status */
434 * XXX this returns to our caller's caller (as is required) since
435 * we didn't set up a frame and our caller did.
441 * If we have a kernelname copy it in
443 movl BI_KERNELNAME(%ebx),%esi
445 je 2f /* No kernelname */
446 movl $MAXPATHLEN,%ecx /* Brute force!!! */
447 movl $R(kernelname),%edi
448 cmpb $'/',(%esi) /* Make sure it starts with a slash */
460 * Determine the size of the boot loader's copy of the bootinfo
461 * struct. This is impossible to do properly because old versions
462 * of the struct don't contain a size field and there are 2 old
463 * versions with the same version number.
465 movl $BI_ENDCOMMON,%ecx /* prepare for sizeless version */
466 testl $RB_BOOTINFO,8(%ebp) /* bi_size (and bootinfo) valid? */
467 je got_bi_size /* no, sizeless version */
468 movl BI_SIZE(%ebx),%ecx
472 * Copy the common part of the bootinfo struct
475 movl $R(bootinfo),%edi
476 cmpl $BOOTINFO_SIZE,%ecx
477 jbe got_common_bi_size
478 movl $BOOTINFO_SIZE,%ecx
487 * If we have a nfs_diskless structure copy it in
489 movl BI_NFS_DISKLESS(%ebx),%esi
492 movl $R(nfs_diskless),%edi
493 movl $NFSDISKLESS_SIZE,%ecx
497 movl $R(nfs_diskless_valid),%edi
503 * The old style disk boot.
504 * (*btext)(howto, bootdev, cyloffset, esym);
505 * Note that the newer boot code just falls into here to pick
506 * up howto and bootdev, cyloffset and esym are no longer used
510 movl %eax,R(boothowto)
517 /**********************************************************************
519 * Identify the CPU and initialize anything special about it
524 /* Try to toggle alignment check flag; does not exist on 386. */
541 /* NexGen CPU does not have aligment check flag. */
555 movl $CPU_NX586,R(cpu)
556 movl $0x4778654e,R(cpu_vendor) # store vendor string
557 movl $0x72446e65,R(cpu_vendor+4)
558 movl $0x6e657669,R(cpu_vendor+8)
559 movl $0,R(cpu_vendor+12)
562 try486: /* Try to toggle identification flag; does not exist on early 486s. */
582 * Cyrix CPUs do not change the undefined flags following
583 * execution of the divide instruction which divides 5 by 2.
585 * Note: CPUID is enabled on M2, so it passes another way.
595 jmp 3f /* You may use Intel CPU. */
600 * IBM Bluelighting CPU also doesn't change the undefined flags.
601 * Because IBM doesn't disclose the information for Bluelighting
602 * CPU, we couldn't distinguish it from Cyrix's (including IBM
603 * brand of Cyrix CPUs).
605 movl $0x69727943,R(cpu_vendor) # store vendor string
606 movl $0x736e4978,R(cpu_vendor+4)
607 movl $0x64616574,R(cpu_vendor+8)
610 trycpuid: /* Use the `cpuid' instruction. */
613 movl %eax,R(cpu_high) # highest capability
614 movl %ebx,R(cpu_vendor) # store vendor string
615 movl %edx,R(cpu_vendor+4)
616 movl %ecx,R(cpu_vendor+8)
617 movb $0,R(cpu_vendor+12)
621 movl %eax,R(cpu_id) # store cpu_id
622 movl %ebx,R(cpu_procinfo) # store cpu_procinfo
623 movl %edx,R(cpu_feature) # store cpu_feature
624 rorl $8,%eax # extract family type
629 /* less than Pentium; must be 486 */
639 /* Greater than Pentium...call it a Pentium Pro */
645 /**********************************************************************
647 * Create the first page directory and its page tables.
653 /* Find end of kernel image (rounded up to a page boundary). */
656 /* Include symbols, if any. */
657 movl R(bootinfo+BI_ESYMTAB),%edi
662 addl %edi,R(bootinfo+BI_SYMTAB)
663 addl %edi,R(bootinfo+BI_ESYMTAB)
666 /* If we are told where the end of the kernel space is, believe it. */
667 movl R(bootinfo+BI_KERNEND),%edi
674 andl $~PAGE_MASK,%esi
675 movl %esi,R(KERNend) /* save end of kernel */
676 movl %esi,R(physfree) /* next free page is at end of kernel */
679 /* Allocate Kernel Page Tables */
683 /* Allocate Page Table Directory */
687 /* Allocate UPAGES */
691 movl %esi, R(proc0paddr)
693 ALLOCPAGES(1) /* vm86/bios stack */
694 movl %esi,R(vm86phystk)
696 ALLOCPAGES(3) /* pgtable + ext + IOPAGES */
699 movl %esi, R(vm86paddr)
701 /* Allocate cpu0's private data page */
705 movl %esi, R(cpu0prvpage) /* relocated to KVM space */
707 /* Allocate cpu0's idle stack */
709 movl %esi,R(cpu0idlestk)
711 /* Allocate SMP page table page */
715 movl %esi, R(SMPpt) /* relocated to KVM space */
717 /* Map read-only from zero to the end of the kernel text section */
720 /* If the debugger is present, actually map everything read-write. */
721 cmpl $0,R(bdb_exists)
727 testl $CPUID_PGE, R(cpu_feature)
732 2: movl $R(etext),%ecx
734 shrl $PAGE_SHIFT,%ecx
737 /* Map read-write, data, bss and symbols */
739 addl $PAGE_MASK, %eax
740 andl $~PAGE_MASK, %eax
744 testl $CPUID_PGE, R(cpu_feature)
749 1: movl R(KERNend),%ecx
751 shrl $PAGE_SHIFT,%ecx
754 /* Map page directory. */
755 movl R(IdlePTD), %eax
759 /* Map proc0's UPAGES in the physical way ... */
765 movl $ISA_HOLE_START, %eax
766 movl $ISA_HOLE_LENGTH>>PAGE_SHIFT, %ecx
769 /* Map space for the vm86 region */
770 movl R(vm86phystk), %eax
774 /* Map page 0 into the vm86 page table */
778 fillkpt(R(vm86pa), $PG_RW|PG_U)
780 /* ...likewise for the ISA hole */
781 movl $ISA_HOLE_START, %eax
782 movl $ISA_HOLE_START>>PAGE_SHIFT, %ebx
783 movl $ISA_HOLE_LENGTH>>PAGE_SHIFT, %ecx
784 fillkpt(R(vm86pa), $PG_RW|PG_U)
786 /* Map cpu0's private page into global kmem (4K @ cpu0prvpage) */
791 /* Map SMP page table page into global kmem FWIW */
792 movl R(SMPptpa), %eax
796 /* Map the private page into the SMP page table */
798 movl $0, %ebx /* pte offset = 0 */
799 movl $1, %ecx /* one private page coming right up */
800 fillkpt(R(SMPptpa), $PG_RW)
802 /* Map the cpu0's idle thread stack */
803 movl R(cpu0idlestk), %eax
804 movl $PS_IDLESTACK_PAGE, %ebx
806 fillkpt(R(SMPptpa), $PG_RW)
808 /* ... and put the page table table in the pde. */
809 movl R(SMPptpa), %eax
812 fillkpt(R(IdlePTD), $PG_RW)
814 /* Fakeup VA for the local apic to allow early traps. */
817 movl $(NPTEPG-1), %ebx /* pte offset = NTEPG-1 */
818 movl $1, %ecx /* one private pt coming right up */
819 fillkpt(R(SMPptpa), $PG_RW)
822 /* Initialize mp lock to allow early traps */
826 /* install a pde for temporary double map of bottom of VA */
827 movl R(KPTphys), %eax
830 fillkpt(R(IdlePTD), $PG_RW)
832 /* install pde's for pt's */
833 movl R(KPTphys), %eax
836 fillkpt(R(IdlePTD), $PG_RW)
838 /* install a pde recursively mapping page directory as a page table */
839 movl R(IdlePTD), %eax
842 fillkpt(R(IdlePTD), $PG_RW)
848 cmpl $0,R(bdb_exists)
849 je bdb_prepare_paging_exit
854 * Copy and convert debugger entries from the bootstrap gdt and idt
855 * to the kernel gdt and idt. Everything is still in low memory.
856 * Tracing continues to work after paging is enabled because the
857 * low memory addresses remain valid until everything is relocated.
858 * However, tracing through the setidt() that initializes the trace
862 movl 2(%esp),%esi /* base address of bootstrap gdt */
864 movl %edi,2(%esp) /* prepare to load kernel gdt */
869 movl $R(gdt),-8+2(%edi) /* adjust gdt self-ptr */
870 movb $0x92,-8+5(%edi)
874 movl 2(%esp),%esi /* base address of current idt */
875 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */
877 movl %eax,R(bdb_dbg_ljmp+1) /* ... immediate offset ... */
879 movw %ax,R(bdb_dbg_ljmp+5) /* ... and selector for ljmp */
880 movl 24+4(%esi),%eax /* same for bpt descriptor */
882 movl %eax,R(bdb_bpt_ljmp+1)
884 movw %ax,R(bdb_bpt_ljmp+5)
886 movl %edi,2(%esp) /* prepare to load kernel idt */
895 bdb_prepare_paging_exit:
898 /* Relocate debugger gdt entries and gdt and idt pointers. */
901 je bdb_commit_paging_exit
903 movl $_gdt+8*9,%eax /* adjust slots 9-17 */
906 movb $KERNBASE>>24,7(%eax) /* top byte of base addresses, was 0, */
907 addl $8,%eax /* now KERNBASE>>24 */
912 addl $KERNBASE,2(%esp)
915 addl $KERNBASE,2(%esp)
921 bdb_commit_paging_exit:
924 #endif /* BDE_DEBUGGER */