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 1.12 2006/12/27 17:20:28 tgen 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_feature2, 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_feature2: .long 0 /* additional features */
113 cpu_procinfo: .long 0 /* brand index / HTT info */
114 cpu_vendor: .space 20 /* CPU origin code */
115 bootinfo: .space BOOTINFO_SIZE /* bootinfo buffer space */
117 KERNend: .long 0 /* phys addr end of kernel (just after bss) */
118 physfree: .long 0 /* phys addr of next free page */
122 cpu0prvpage: .long 0 /* relocated version */
124 cpu0pp: .long 0 /* phys addr cpu0 private pg */
125 cpu0idlestk: .long 0 /* stack for the idle thread */
128 SMPptpa: .long 0 /* phys addr SMP page table */
129 SMPpt: .long 0 /* relocated version */
132 IdlePTD: .long 0 /* phys addr of kernel PTD */
135 KPTphys: .long 0 /* PA of kernel page tables */
138 proc0paddr: .long 0 /* VA of proc 0 address space */
139 p0upa: .long 0 /* PA of proc0's UPAGES */
141 vm86phystk: .long 0 /* PA of vm86/bios stack */
143 .globl vm86paddr, vm86pa
144 vm86paddr: .long 0 /* address of vm86 region */
145 vm86pa: .long 0 /* phys addr of vm86 region */
148 .globl bdb_exists /* BDE debugger is present */
152 /**********************************************************************
158 #define R(foo) ((foo)-KERNBASE)
160 #define ALLOCPAGES(foo) \
161 movl R(physfree), %esi ; \
162 movl $((foo)*PAGE_SIZE), %eax ; \
164 movl %eax, R(physfree) ; \
166 movl $((foo)*PAGE_SIZE),%ecx ; \
174 * eax = page frame address
175 * ebx = index into page table
176 * ecx = how many pages to map
177 * base = base address of page dir/table
178 * prot = protection bits
180 #define fillkpt(base, prot) \
185 1: movl %eax,(%ebx) ; \
186 addl $PAGE_SIZE,%eax ; /* increment physical address */ \
187 addl $4,%ebx ; /* next pte */ \
192 * eax = physical address
193 * ecx = how many pages to map
194 * prot = protection bits
196 #define fillkptphys(prot) \
198 shrl $PAGE_SHIFT, %ebx ; \
199 fillkpt(R(KPTphys), prot)
202 /**********************************************************************
204 * This is where the bootblocks start us, set the ball rolling...
207 NON_GPROF_ENTRY(btext)
210 #ifdef BIOS_STEALS_3K
211 cmpl $0x0375c339,0x95504
213 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */
216 movb $1,R(bdb_exists)
219 /* Tell the bios to warmboot next time */
222 /* Set up a real frame in case the double return in newboot is executed. */
226 /* Don't trust what the BIOS gives for eflags. */
231 * Don't trust what the BIOS gives for %fs and %gs. Trust the bootstrap
232 * to set %cs, %ds, %es and %ss.
239 * Clear the bss. Not all boot programs do it, and it is our job anyway.
241 * XXX we don't check that there is memory for our bss and page tables
244 * Note: we must be careful to not overwrite an active gdt or idt. They
245 * inactive from now until we switch to new ones, since we don't load any
246 * more segment registers or permit interrupts until after the switch.
256 call recover_bootinfo
258 /* Get onto a stack that we can trust. */
260 * XXX this step is delayed in case recover_bootinfo needs to return via
261 * the old stack, but it need not be, since recover_bootinfo actually
262 * returns via the old frame.
264 movl $R(.tmpstk),%esp
268 call create_pagetables
271 * If the CPU has support for VME, turn it on.
273 testl $CPUID_VME, R(cpu_feature)
282 * Adjust as much as possible for paging before enabling paging so that the
283 * adjustments can be traced.
285 call bdb_prepare_paging
288 /* Now enable paging */
289 movl R(IdlePTD), %eax
290 movl %eax,%cr3 /* load ptd addr into mmu */
291 movl %cr0,%eax /* get control word */
292 orl $CR0_PE|CR0_PG,%eax /* enable paging */
293 movl %eax,%cr0 /* and let's page NOW! */
298 * Complete the adjustments for paging so that we can keep tracing through
299 * initi386() after the low (physical) addresses for the gdt and idt become
302 call bdb_commit_paging
305 pushl $begin /* jump to high virtualized address */
308 /* now running relocated at KERNBASE where the system is linked to run */
312 * set up the bootstrap stack. The pcb sits at the end of the
315 /* set up bootstrap stack */
316 movl proc0paddr,%esp /* location of in-kernel pages */
317 addl $UPAGES*PAGE_SIZE-PCB_SIZE,%esp
318 xorl %eax,%eax /* mark end of frames */
320 /*movl proc0paddr,%eax*/
322 movl %esi,PCB_CR3(%esp)
324 testl $CPUID_PGE, R(cpu_feature)
332 pushl %esi /* value of first for init386(first) */
334 call init386 /* wire 386 chip for unix operation */
337 call mi_startup /* autoconfiguration, mountroot etc */
339 hlt /* never returns to here */
342 * Signal trampoline, copied to top of user stack
344 NON_GPROF_ENTRY(sigcode)
345 call *SIGF_HANDLER(%esp) /* call signal handler */
346 lea SIGF_UC(%esp),%eax /* get ucontext_t */
348 testl $PSL_VM,UC_EFLAGS(%eax)
350 movl UC_GS(%eax),%gs /* restore %gs */
352 movl $SYS_sigreturn,%eax
353 pushl %eax /* junk to fake return addr. */
354 int $0x80 /* enter kernel with args */
363 .long esigcode - sigcode
366 /**********************************************************************
368 * Recover the bootinfo passed to us from the boot program
373 * This code is called in different ways depending on what loaded
374 * and started the kernel. This is used to detect how we get the
375 * arguments from the other code and what we do with them.
377 * Old disk boot blocks:
378 * (*btext)(howto, bootdev, cyloffset, esym);
379 * [return address == 0, and can NOT be returned to]
380 * [cyloffset was not supported by the FreeBSD boot code
381 * and always passed in as 0]
382 * [esym is also known as total in the boot code, and
383 * was never properly supported by the FreeBSD boot code]
385 * Old diskless netboot code:
386 * (*btext)(0,0,0,0,&nfsdiskless,0,0,0);
387 * [return address != 0, and can NOT be returned to]
388 * If we are being booted by this code it will NOT work,
389 * so we are just going to halt if we find this case.
391 * New uniform boot code:
392 * (*btext)(howto, bootdev, 0, 0, 0, &bootinfo)
393 * [return address != 0, and can be returned to]
395 * There may seem to be a lot of wasted arguments in here, but
396 * that is so the newer boot code can still load very old kernels
397 * and old boot code can load new kernels.
401 * The old style disk boot blocks fake a frame on the stack and
402 * did an lret to get here. The frame on the stack has a return
409 * We have some form of return address, so this is either the
410 * old diskless netboot code, or the new uniform code. That can
411 * be detected by looking at the 5th argument, if it is 0
412 * we are being booted by the new uniform boot code.
418 * Seems we have been loaded by the old diskless boot code, we
419 * don't stand a chance of running as the diskless structure
420 * changed considerably between the two, so just halt.
425 * We have been loaded by the new uniform boot code.
426 * Let's check the bootinfo version, and if we do not understand
427 * it we return to the loader with a status of 1 to indicate this error
430 movl 28(%ebp),%ebx /* &bootinfo.version */
431 movl BI_VERSION(%ebx),%eax
432 cmpl $1,%eax /* We only understand version 1 */
434 movl $1,%eax /* Return status */
437 * XXX this returns to our caller's caller (as is required) since
438 * we didn't set up a frame and our caller did.
444 * If we have a kernelname copy it in
446 movl BI_KERNELNAME(%ebx),%esi
448 je 2f /* No kernelname */
449 movl $MAXPATHLEN,%ecx /* Brute force!!! */
450 movl $R(kernelname),%edi
451 cmpb $'/',(%esi) /* Make sure it starts with a slash */
463 * Determine the size of the boot loader's copy of the bootinfo
464 * struct. This is impossible to do properly because old versions
465 * of the struct don't contain a size field and there are 2 old
466 * versions with the same version number.
468 movl $BI_ENDCOMMON,%ecx /* prepare for sizeless version */
469 testl $RB_BOOTINFO,8(%ebp) /* bi_size (and bootinfo) valid? */
470 je got_bi_size /* no, sizeless version */
471 movl BI_SIZE(%ebx),%ecx
475 * Copy the common part of the bootinfo struct
478 movl $R(bootinfo),%edi
479 cmpl $BOOTINFO_SIZE,%ecx
480 jbe got_common_bi_size
481 movl $BOOTINFO_SIZE,%ecx
490 * If we have a nfs_diskless structure copy it in
492 movl BI_NFS_DISKLESS(%ebx),%esi
495 movl $R(nfs_diskless),%edi
496 movl $NFSDISKLESS_SIZE,%ecx
500 movl $R(nfs_diskless_valid),%edi
506 * The old style disk boot.
507 * (*btext)(howto, bootdev, cyloffset, esym);
508 * Note that the newer boot code just falls into here to pick
509 * up howto and bootdev, cyloffset and esym are no longer used
513 movl %eax,R(boothowto)
520 /**********************************************************************
522 * Identify the CPU and initialize anything special about it
527 /* Try to toggle alignment check flag; does not exist on 386. */
544 /* NexGen CPU does not have aligment check flag. */
558 movl $CPU_NX586,R(cpu)
559 movl $0x4778654e,R(cpu_vendor) # store vendor string
560 movl $0x72446e65,R(cpu_vendor+4)
561 movl $0x6e657669,R(cpu_vendor+8)
562 movl $0,R(cpu_vendor+12)
565 try486: /* Try to toggle identification flag; does not exist on early 486s. */
585 * Cyrix CPUs do not change the undefined flags following
586 * execution of the divide instruction which divides 5 by 2.
588 * Note: CPUID is enabled on M2, so it passes another way.
598 jmp 3f /* You may use Intel CPU. */
603 * IBM Bluelighting CPU also doesn't change the undefined flags.
604 * Because IBM doesn't disclose the information for Bluelighting
605 * CPU, we couldn't distinguish it from Cyrix's (including IBM
606 * brand of Cyrix CPUs).
608 movl $0x69727943,R(cpu_vendor) # store vendor string
609 movl $0x736e4978,R(cpu_vendor+4)
610 movl $0x64616574,R(cpu_vendor+8)
613 trycpuid: /* Use the `cpuid' instruction. */
616 movl %eax,R(cpu_high) # highest capability
617 movl %ebx,R(cpu_vendor) # store vendor string
618 movl %edx,R(cpu_vendor+4)
619 movl %ecx,R(cpu_vendor+8)
620 movb $0,R(cpu_vendor+12)
624 movl %eax,R(cpu_id) # store cpu_id
625 movl %ebx,R(cpu_procinfo) # store cpu_procinfo
626 movl %edx,R(cpu_feature) # store cpu_feature
627 movl %ecx,R(cpu_feature2) # store cpu_feature2
628 rorl $8,%eax # extract family type
633 /* less than Pentium; must be 486 */
643 /* Greater than Pentium...call it a Pentium Pro */
649 /**********************************************************************
651 * Create the first page directory and its page tables.
657 /* Find end of kernel image (rounded up to a page boundary). */
660 /* Include symbols, if any. */
661 movl R(bootinfo+BI_ESYMTAB),%edi
666 addl %edi,R(bootinfo+BI_SYMTAB)
667 addl %edi,R(bootinfo+BI_ESYMTAB)
670 /* If we are told where the end of the kernel space is, believe it. */
671 movl R(bootinfo+BI_KERNEND),%edi
678 andl $~PAGE_MASK,%esi
679 movl %esi,R(KERNend) /* save end of kernel */
680 movl %esi,R(physfree) /* next free page is at end of kernel */
683 /* Allocate Kernel Page Tables */
687 /* Allocate Page Table Directory */
691 /* Allocate UPAGES */
695 movl %esi, R(proc0paddr)
697 ALLOCPAGES(1) /* vm86/bios stack */
698 movl %esi,R(vm86phystk)
700 ALLOCPAGES(3) /* pgtable + ext + IOPAGES */
703 movl %esi, R(vm86paddr)
705 /* Allocate cpu0's mdglobaldata */
706 ALLOCPAGES(MDGLOBALDATA_BASEALLOC_PAGES)
710 movl %esi, R(cpu0prvpage) /* relocated to KVM space */
713 /* Allocate cpu0's idle stack */
715 movl %esi,R(cpu0idlestk)
717 /* Allocate SMP page table page */
721 movl %esi, R(SMPpt) /* relocated to KVM space */
723 /* Map read-only from zero to the end of the kernel text section */
726 /* If the debugger is present, actually map everything read-write. */
727 cmpl $0,R(bdb_exists)
733 testl $CPUID_PGE, R(cpu_feature)
738 2: movl $R(etext),%ecx
740 shrl $PAGE_SHIFT,%ecx
743 /* Map read-write, data, bss and symbols */
745 addl $PAGE_MASK, %eax
746 andl $~PAGE_MASK, %eax
750 testl $CPUID_PGE, R(cpu_feature)
755 1: movl R(KERNend),%ecx
757 shrl $PAGE_SHIFT,%ecx
760 /* Map page directory. */
761 movl R(IdlePTD), %eax
765 /* Map proc0's UPAGES in the physical way ... */
771 movl $ISA_HOLE_START, %eax
772 movl $ISA_HOLE_LENGTH>>PAGE_SHIFT, %ecx
775 /* Map space for the vm86 region */
776 movl R(vm86phystk), %eax
780 /* Map page 0 into the vm86 page table */
784 fillkpt(R(vm86pa), $PG_RW|PG_U)
786 /* ...likewise for the ISA hole */
787 movl $ISA_HOLE_START, %eax
788 movl $ISA_HOLE_START>>PAGE_SHIFT, %ebx
789 movl $ISA_HOLE_LENGTH>>PAGE_SHIFT, %ecx
790 fillkpt(R(vm86pa), $PG_RW|PG_U)
793 /* Map cpu0's mdglobaldata into global kmem (N pages @ cpu0pp) */
795 movl $MDGLOBALDATA_BASEALLOC_PAGES, %ecx
799 /* Map SMP page table page into global kmem FWIW */
800 movl R(SMPptpa), %eax
804 /* Map the private page into the SMP page table */
806 movl $0, %ebx /* pte offset = 0 */
807 /* N private pages coming right up */
808 movl $MDGLOBALDATA_BASEALLOC_PAGES, %ecx
809 fillkpt(R(SMPptpa), $PG_RW)
811 /* Map the cpu0's idle thread stack */
812 movl R(cpu0idlestk), %eax
813 movl $PS_IDLESTACK_PAGE, %ebx
815 fillkpt(R(SMPptpa), $PG_RW)
817 /* ... and put the page table table in the pde. */
818 movl R(SMPptpa), %eax
821 fillkpt(R(IdlePTD), $PG_RW)
823 /* Fakeup VA for the local apic to allow early traps. */
826 movl $(NPTEPG-1), %ebx /* pte offset = NTEPG-1 */
827 movl $1, %ecx /* one private pt coming right up */
828 fillkpt(R(SMPptpa), $PG_RW)
831 /* Initialize mp lock to allow early traps */
835 /* install a pde for temporary double map of bottom of VA */
836 movl R(KPTphys), %eax
839 fillkpt(R(IdlePTD), $PG_RW)
841 /* install pde's for pt's */
842 movl R(KPTphys), %eax
845 fillkpt(R(IdlePTD), $PG_RW)
847 /* install a pde recursively mapping page directory as a page table */
848 movl R(IdlePTD), %eax
851 fillkpt(R(IdlePTD), $PG_RW)
857 cmpl $0,R(bdb_exists)
858 je bdb_prepare_paging_exit
863 * Copy and convert debugger entries from the bootstrap gdt and idt
864 * to the kernel gdt and idt. Everything is still in low memory.
865 * Tracing continues to work after paging is enabled because the
866 * low memory addresses remain valid until everything is relocated.
867 * However, tracing through the setidt() that initializes the trace
871 movl 2(%esp),%esi /* base address of bootstrap gdt */
873 movl %edi,2(%esp) /* prepare to load kernel gdt */
878 movl $R(gdt),-8+2(%edi) /* adjust gdt self-ptr */
879 movb $0x92,-8+5(%edi)
883 movl 2(%esp),%esi /* base address of current idt */
884 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */
886 movl %eax,R(bdb_dbg_ljmp+1) /* ... immediate offset ... */
888 movw %ax,R(bdb_dbg_ljmp+5) /* ... and selector for ljmp */
889 movl 24+4(%esi),%eax /* same for bpt descriptor */
891 movl %eax,R(bdb_bpt_ljmp+1)
893 movw %ax,R(bdb_bpt_ljmp+5)
895 movl %edi,2(%esp) /* prepare to load kernel idt */
904 bdb_prepare_paging_exit:
907 /* Relocate debugger gdt entries and gdt and idt pointers. */
910 je bdb_commit_paging_exit
912 movl $_gdt+8*9,%eax /* adjust slots 9-17 */
915 movb $KERNBASE>>24,7(%eax) /* top byte of base addresses, was 0, */
916 addl $8,%eax /* now KERNBASE>>24 */
921 addl $KERNBASE,2(%esp)
924 addl $KERNBASE,2(%esp)
930 bdb_commit_paging_exit:
933 #endif /* BDE_DEBUGGER */