locore.s revision 2500
1/*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * William Jolitz. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 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. 23 * 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 34 * SUCH DAMAGE. 35 * 36 * from: @(#)locore.s 7.3 (Berkeley) 5/13/91 37 * $Id: locore.s,v 1.24 1994/09/04 19:59:13 pst Exp $ 38 */ 39 40/* 41 * locore.s: FreeBSD machine support for the Intel 386 42 * originally from: locore.s, by William F. Jolitz 43 * 44 * Substantially rewritten by David Greenman, Rod Grimes, 45 * Bruce Evans, Wolfgang Solfrank, and many others. 46 */ 47 48#include "npx.h" /* for NNPX */ 49#include "assym.s" /* system definitions */ 50#include <machine/psl.h> /* processor status longword defs */ 51#include <machine/pte.h> /* page table entry definitions */ 52#include <sys/errno.h> /* error return codes */ 53#include <machine/specialreg.h> /* x86 special registers */ 54#include <machine/cputypes.h> /* x86 cpu type definitions */ 55#include <sys/syscall.h> /* system call numbers */ 56#include <machine/asmacros.h> /* miscellaneous asm macros */ 57 58/* 59 * XXX 60 * 61 * Note: This version greatly munged to avoid various assembler errors 62 * that may be fixed in newer versions of gas. Perhaps newer versions 63 * will have more pleasant appearance. 64 */ 65 66/* 67 * PTmap is recursive pagemap at top of virtual address space. 68 * Within PTmap, the page directory can be found (third indirection). 69 */ 70 .globl _PTmap,_PTD,_PTDpde,_Sysmap 71 .set _PTmap,PTDPTDI << PDRSHIFT 72 .set _PTD,_PTmap + (PTDPTDI * NBPG) 73 .set _PTDpde,_PTD + (PTDPTDI * PDESIZE) 74 75/* Sysmap is the base address of the kernel page tables */ 76 .set _Sysmap,_PTmap + (KPTDI * NBPG) 77 78/* 79 * APTmap, APTD is the alternate recursive pagemap. 80 * It's used when modifying another process's page tables. 81 */ 82 .globl _APTmap,_APTD,_APTDpde 83 .set _APTmap,APTDPTDI << PDRSHIFT 84 .set _APTD,_APTmap + (APTDPTDI * NBPG) 85 .set _APTDpde,_PTD + (APTDPTDI * PDESIZE) 86 87/* 88 * Access to each processes kernel stack is via a region of 89 * per-process address space (at the beginning), immediatly above 90 * the user process stack. 91 */ 92 .set _kstack,USRSTACK 93 .globl _kstack 94 95/* 96 * Globals 97 */ 98 .data 99 .globl _esym 100_esym: .long 0 /* ptr to end of syms */ 101 102 .globl _boothowto,_bootdev,_curpcb 103 104 .globl _cpu,_cold,_atdevbase,_cpu_vendor,_cpu_id 105_cpu: .long 0 /* are we 386, 386sx, or 486 */ 106_cpu_id: .long 0 /* stepping ID */ 107_cpu_vendor: .space 20 /* CPU origin code */ 108_cold: .long 1 /* cold till we are not */ 109_atdevbase: .long 0 /* location of start of iomem in virtual */ 110_atdevphys: .long 0 /* location of device mapping ptes (phys) */ 111 112 .globl _KERNend 113_KERNend: .long 0 /* phys addr end of kernel (just after bss) */ 114 115 .globl _IdlePTD,_KPTphys 116_IdlePTD: .long 0 /* phys addr of kernel PTD */ 117_KPTphys: .long 0 /* phys addr of kernel page tables */ 118 119 .globl _cyloffset 120_cyloffset: .long 0 /* cylinder offset from boot blocks */ 121 122 .globl _proc0paddr 123_proc0paddr: .long 0 /* address of proc 0 address space */ 124 125#ifdef BDE_DEBUGGER 126 .globl _bdb_exists /* flag to indicate BDE debugger is available */ 127_bdb_exists: .long 0 128#endif 129 130 .globl tmpstk 131 .space 0x1000 132tmpstk: 133 134 135/* 136 * System Initialization 137 */ 138 .text 139 140/* 141 * btext: beginning of text section. 142 * Also the entry point (jumped to directly from the boot blocks). 143 */ 144NON_GPROF_ENTRY(btext) 145 movw $0x1234,0x472 /* warm boot */ 146 jmp 1f 147 .org 0x500 /* space for BIOS variables */ 148 149 1: 150 /* don't trust what the BIOS gives for eflags */ 151 pushl $PSL_MBO 152 popfl 153 154 /* 155 * pass parameters on stack (howto, bootdev, unit, cyloffset, esym) 156 * note: (%esp) is return address of boot 157 * ( if we want to hold onto /boot, it's physical %esp up to _end) 158 */ 159 160 movl 4(%esp),%eax 161 movl %eax,_boothowto-KERNBASE 162 movl 8(%esp),%eax 163 movl %eax,_bootdev-KERNBASE 164 movl 12(%esp),%eax 165 movl %eax,_cyloffset-KERNBASE 166 movl 16(%esp),%eax 167 addl $KERNBASE,%eax 168 movl %eax,_esym-KERNBASE 169#ifdef DISKLESS /* Copy diskless structure */ 170 movl _nfs_diskless_size-KERNBASE,%ecx 171 movl 20(%esp),%esi 172 movl $(_nfs_diskless-KERNBASE),%edi 173 cld 174 rep 175 movsb 176#endif 177 178 /* Find out our CPU type. */ 179 180 /* Try to toggle alignment check flag; does not exist on 386. */ 181 pushfl 182 popl %eax 183 movl %eax,%ecx 184 orl $PSL_AC,%eax 185 pushl %eax 186 popfl 187 pushfl 188 popl %eax 189 xorl %ecx,%eax 190 andl $PSL_AC,%eax 191 pushl %ecx 192 popfl 193 194 testl %eax,%eax 195 jnz 1f 196 movl $CPU_386,_cpu-KERNBASE 197 jmp 2f 198 1991: /* Try to toggle identification flag; does not exist on early 486s. */ 200 pushfl 201 popl %eax 202 movl %eax,%ecx 203 xorl $PSL_ID,%eax 204 pushl %eax 205 popfl 206 pushfl 207 popl %eax 208 xorl %ecx,%eax 209 andl $PSL_ID,%eax 210 pushl %ecx 211 popfl 212 213 testl %eax,%eax 214 jnz 1f 215 movl $CPU_486,_cpu-KERNBASE 216 217 /* check for Cyrix 486DLC -- based on check routine */ 218 /* documented in "Cx486SLC/e SMM Programmer's Guide" */ 219 xorw %dx,%dx 220 cmpw %dx,%dx # set flags to known state 221 pushfw 222 popw %cx # store flags in ecx 223 movw $0xffff,%ax 224 movw $0x0004,%bx 225 divw %bx 226 pushfw 227 popw %ax 228 andw $0x08d5,%ax # mask off important bits 229 andw $0x08d5,%cx 230 cmpw %ax,%cx 231 232 jnz 2f # if flags changed, Intel chip 233 234 movl $CPU_486DLC,_cpu-KERNBASE # set CPU value for Cyrix 235 movl $0x69727943,_cpu_vendor-KERNBASE # store vendor string 236 movw $0x0078,_cpu_vendor-KERNBASE+4 237 238 invd # Start with guaranteed clean cache 239 /* Disable caching of the ISA hole only. */ 240 movb $CCR0,%al # Configuration Register index (CCR0) 241 outb %al,$0x22 242 inb $0x23,%al 243 orb $CCR0_NC1,%al 244 outb %al,$0x23 245 invd 246 jmp 2f 247 2481: /* Use the `cpuid' instruction. */ 249 xorl %eax,%eax 250 .byte 0x0f,0xa2 # cpuid 0 251 movl %ebx,_cpu_vendor-KERNBASE # store vendor string 252 movl %edx,_cpu_vendor+4-KERNBASE 253 movl %ecx,_cpu_vendor+8-KERNBASE 254 movb $0,_cpu_vendor+12-KERNBASE 255 256 movl $1,%eax 257 .byte 0x0f,0xa2 # cpuid 1 258 movl %eax,_cpu_id-KERNBASE # store cpu_id 259 rorl $8,%eax # extract family type 260 andl $15,%eax 261 cmpl $5,%eax 262 jae 1f 263 264 /* less than Pentium; must be 486 */ 265 movl $CPU_486,_cpu-KERNBASE 266 jmp 2f 267 2681: movl $CPU_586,_cpu-KERNBASE 2692: 270 271 /* 272 * Finished with old stack; load new %esp now instead of later so 273 * we can trace this code without having to worry about the trace 274 * trap clobbering the memory test or the zeroing of the bss+bootstrap 275 * page tables. 276 * 277 * XXX - wdboot clears the bss after testing that this is safe. 278 * This is too wasteful - memory below 640K is scarce. The boot 279 * program should check: 280 * text+data <= &stack_variable - more_space_for_stack 281 * text+data+bss+pad+space_for_page_tables <= end_of_memory 282 * Oops, the gdt is in the carcass of the boot program so clearing 283 * the rest of memory is still not possible. 284 */ 285 movl $tmpstk-KERNBASE,%esp /* bootstrap stack end location */ 286 287/* 288 * Virtual address space of kernel: 289 * 290 * text | data | bss | [syms] | page dir | proc0 kernel stack | usr stk map | Sysmap 291 * pages: 1 UPAGES (2) 1 NKPT (7) 292 */ 293 294/* find end of kernel image */ 295 movl $_end-KERNBASE,%ecx 296 addl $NBPG-1,%ecx /* page align up */ 297 andl $~(NBPG-1),%ecx 298 movl %ecx,%esi /* esi = start of free memory */ 299 movl %ecx,_KERNend-KERNBASE /* save end of kernel */ 300 301/* clear bss */ 302 movl $_edata-KERNBASE,%edi 303 subl %edi,%ecx /* get amount to clear */ 304 xorl %eax,%eax /* specify zero fill */ 305 cld 306 rep 307 stosb 308 309/* 310 * The value in esi is both the end of the kernel bss and a pointer to 311 * the kernel page directory, and is used by the rest of locore to build 312 * the tables. 313 * esi + 1(page dir) + 2(UPAGES) + 1(p0stack) + NKPT(number of kernel 314 * page table pages) is then passed on the stack to init386(first) as 315 * the value first. esi should ALWAYS be page aligned!! 316 */ 317 movl %esi,%ecx /* Get current first availiable address */ 318 319/* clear pagetables, page directory, stack, etc... */ 320 movl %esi,%edi /* base (page directory) */ 321 movl $((1+UPAGES+1+NKPT)*NBPG),%ecx /* amount to clear */ 322 xorl %eax,%eax /* specify zero fill */ 323 cld 324 rep 325 stosb 326 327/* physical address of Idle proc/kernel page directory */ 328 movl %esi,_IdlePTD-KERNBASE 329 330/* 331 * fillkpt 332 * eax = (page frame address | control | status) == pte 333 * ebx = address of page table 334 * ecx = how many pages to map 335 */ 336#define fillkpt \ 3371: movl %eax,(%ebx) ; \ 338 addl $NBPG,%eax ; /* increment physical address */ \ 339 addl $4,%ebx ; /* next pte */ \ 340 loop 1b ; 341 342/* 343 * Map Kernel 344 * 345 * First step - build page tables 346 */ 347#if defined (KGDB) || defined (BDE_DEBUGGER) 348 movl _KERNend-KERNBASE,%ecx /* this much memory, */ 349 shrl $PGSHIFT,%ecx /* for this many PTEs */ 350#ifdef BDE_DEBUGGER 351 cmpl $0xa0,%ecx /* XXX - cover debugger pages */ 352 jae 1f 353 movl $0xa0,%ecx 3541: 355#endif /* BDE_DEBUGGER */ 356 movl $PG_V|PG_KW,%eax /* kernel R/W, valid, cache write-through */ 357 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 358 movl %ebx,_KPTphys-KERNBASE /* save in global */ 359 fillkpt 360 361#else /* !KGDB && !BDE_DEBUGGER */ 362 /* write protect kernel text (doesn't do a thing for 386's - only 486's) */ 363 movl $_etext-KERNBASE,%ecx /* get size of text */ 364 shrl $PGSHIFT,%ecx /* for this many PTEs */ 365 movl $PG_V|PG_KR,%eax /* specify read only */ 366 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 367 movl %ebx,_KPTphys-KERNBASE /* save in global */ 368 fillkpt 369 370 /* data and bss are r/w */ 371 andl $PG_FRAME,%eax /* strip to just addr of bss */ 372 movl _KERNend-KERNBASE,%ecx /* calculate size */ 373 subl %eax,%ecx 374 shrl $PGSHIFT,%ecx 375 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 376 fillkpt 377#endif /* KGDB || BDE_DEBUGGER */ 378 379/* now initialize the page dir, upages, p0stack PT, and page tables */ 380 381 movl $(1+UPAGES+1+NKPT),%ecx /* number of PTEs */ 382 movl %esi,%eax /* phys address of PTD */ 383 andl $PG_FRAME,%eax /* convert to PFN, should be a NOP */ 384 orl $PG_V|PG_KW,%eax /* valid, kernel read/write, cache write-though */ 385 movl %esi,%ebx /* calculate pte offset to ptd */ 386 shrl $PGSHIFT-2,%ebx 387 addl %esi,%ebx /* address of page directory */ 388 addl $((1+UPAGES+1)*NBPG),%ebx /* offset to kernel page tables */ 389 fillkpt 390 391/* map I/O memory map */ 392 393 movl _KPTphys-KERNBASE,%ebx /* base of kernel page tables */ 394 lea (0xa0 * PTESIZE)(%ebx),%ebx /* hardwire ISA hole at KERNBASE + 0xa0000 */ 395 movl $0x100-0xa0,%ecx /* for this many pte s, */ 396 movl $(0xa0000|PG_V|PG_KW|PG_N),%eax /* valid, kernel read/write, non-cacheable */ 397 movl %ebx,_atdevphys-KERNBASE /* save phys addr of ptes */ 398 fillkpt 399 400 /* map proc 0's kernel stack into user page table page */ 401 402 movl $UPAGES,%ecx /* for this many pte s, */ 403 lea (1*NBPG)(%esi),%eax /* physical address in proc 0 */ 404 lea (KERNBASE)(%eax),%edx /* change into virtual addr */ 405 movl %edx,_proc0paddr-KERNBASE /* save VA for proc 0 init */ 406 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 407 lea ((1+UPAGES)*NBPG)(%esi),%ebx /* addr of stack page table in proc 0 */ 408 addl $(KSTKPTEOFF * PTESIZE),%ebx /* offset to kernel stack PTE */ 409 fillkpt 410 411/* 412 * Initialize kernel page table directory 413 */ 414 /* install a pde for temporary double map of bottom of VA */ 415 movl _KPTphys-KERNBASE,%eax 416 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 417 movl %eax,(%esi) /* which is where temp maps! */ 418 419 /* initialize kernel pde's */ 420 movl $(NKPT),%ecx /* for this many PDEs */ 421 lea (KPTDI*PDESIZE)(%esi),%ebx /* offset of pde for kernel */ 422 fillkpt 423 424 /* install a pde recursively mapping page directory as a page table! */ 425 movl %esi,%eax /* phys address of ptd in proc 0 */ 426 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 427 movl %eax,PTDPTDI*PDESIZE(%esi) /* which is where PTmap maps! */ 428 429 /* install a pde to map kernel stack for proc 0 */ 430 lea ((1+UPAGES)*NBPG)(%esi),%eax /* physical address of pt in proc 0 */ 431 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 432 movl %eax,KSTKPTDI*PDESIZE(%esi) /* which is where kernel stack maps! */ 433 434#ifdef BDE_DEBUGGER 435 /* copy and convert stuff from old gdt and idt for debugger */ 436 437 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */ 438 jne 1f 439 movb $1,_bdb_exists-KERNBASE 4401: 441 pushal 442 subl $2*6,%esp 443 444 sgdt (%esp) 445 movl 2(%esp),%esi /* base address of current gdt */ 446 movl $_gdt-KERNBASE,%edi 447 movl %edi,2(%esp) 448 movl $8*18/4,%ecx 449 cld 450 rep /* copy gdt */ 451 movsl 452 movl $_gdt-KERNBASE,-8+2(%edi) /* adjust gdt self-ptr */ 453 movb $0x92,-8+5(%edi) 454 455 sidt 6(%esp) 456 movl 6+2(%esp),%esi /* base address of current idt */ 457 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */ 458 movw 8(%esi),%ax 459 movl %eax,bdb_dbg_ljmp+1-KERNBASE /* ... immediate offset ... */ 460 movl 8+2(%esi),%eax 461 movw %ax,bdb_dbg_ljmp+5-KERNBASE /* ... and selector for ljmp */ 462 movl 24+4(%esi),%eax /* same for bpt descriptor */ 463 movw 24(%esi),%ax 464 movl %eax,bdb_bpt_ljmp+1-KERNBASE 465 movl 24+2(%esi),%eax 466 movw %ax,bdb_bpt_ljmp+5-KERNBASE 467 468 movl $_idt-KERNBASE,%edi 469 movl %edi,6+2(%esp) 470 movl $8*4/4,%ecx 471 cld 472 rep /* copy idt */ 473 movsl 474 475 lgdt (%esp) 476 lidt 6(%esp) 477 478 addl $2*6,%esp 479 popal 480#endif /* BDE_DEBUGGER */ 481 482 /* load base of page directory and enable mapping */ 483 movl %esi,%eax /* phys address of ptd in proc 0 */ 484 orl $I386_CR3PAT,%eax 485 movl %eax,%cr3 /* load ptd addr into mmu */ 486 movl %cr0,%eax /* get control word */ 487 orl $CR0_PE|CR0_PG,%eax /* enable paging */ 488 movl %eax,%cr0 /* and let's page NOW! */ 489 490 pushl $begin /* jump to high mem */ 491 ret 492 493begin: /* now running relocated at KERNBASE where the system is linked to run */ 494 495 .globl _Crtat /* XXX - locore should not know about */ 496 movl _Crtat,%eax /* variables of device drivers (pccons)! */ 497 subl $(KERNBASE+0xA0000),%eax 498 movl _atdevphys,%edx /* get pte PA */ 499 subl _KPTphys,%edx /* remove base of ptes, now have phys offset */ 500 shll $PGSHIFT-2,%edx /* corresponding to virt offset */ 501 addl $KERNBASE,%edx /* add virtual base */ 502 movl %edx,_atdevbase 503 addl %eax,%edx 504 movl %edx,_Crtat 505 506 /* set up bootstrap stack - 48 bytes */ 507 movl $_kstack+UPAGES*NBPG-4*12,%esp /* bootstrap stack end location */ 508 xorl %eax,%eax /* mark end of frames */ 509 movl %eax,%ebp 510 movl _proc0paddr,%eax 511 movl %esi,PCB_CR3(%eax) 512 513#ifdef BDE_DEBUGGER 514 /* relocate debugger gdt entries */ 515 516 movl $_gdt+8*9,%eax /* adjust slots 9-17 */ 517 movl $9,%ecx 518reloc_gdt: 519 movb $KERNBASE>>24,7(%eax) /* top byte of base addresses, was 0, */ 520 addl $8,%eax /* now KERNBASE>>24 */ 521 loop reloc_gdt 522 523 cmpl $0,_bdb_exists 524 je 1f 525 int $3 5261: 527#endif /* BDE_DEBUGGER */ 528 529 /* 530 * Skip over the page tables and the kernel stack 531 */ 532 lea ((1+UPAGES+1+NKPT)*NBPG)(%esi),%esi 533 534 pushl %esi /* value of first for init386(first) */ 535 call _init386 /* wire 386 chip for unix operation */ 536 popl %esi 537 538 .globl __ucodesel,__udatasel 539 540 pushl $0 /* unused */ 541 pushl __udatasel /* ss */ 542 pushl $0 /* esp - filled in by execve() */ 543 pushl $PSL_USERSET /* eflags (ring 0, int enab) */ 544 pushl __ucodesel /* cs */ 545 pushl $0 /* eip - filled in by execve() */ 546 subl $(12*4),%esp /* space for rest of registers */ 547 548 pushl %esp /* call main with frame pointer */ 549 call _main /* autoconfiguration, mountroot etc */ 550 551 addl $(13*4),%esp /* back to a frame we can return with */ 552 553 /* 554 * now we've run main() and determined what cpu-type we are, we can 555 * enable WP mode on i486 cpus and above. 556 */ 557#if defined(I486_CPU) || defined(I586_CPU) 558 cmpl $CPUCLASS_386,_cpu_class 559 je 1f 560 movl %cr0,%eax /* get control word */ 561 orl $CR0_WP,%eax /* enable write protect for all modes */ 562 movl %eax,%cr0 /* and do it */ 563#endif 564 /* 565 * on return from main(), we are process 1 566 * set up address space and stack so that we can 'return' to user mode 567 */ 5681: 569 movl __ucodesel,%eax 570 movl __udatasel,%ecx 571 572 movl %cx,%ds 573 movl %cx,%es 574 movl %ax,%fs /* double map cs to fs */ 575 movl %cx,%gs /* and ds to gs */ 576 iret /* goto user! */ 577 578#define LCALL(x,y) .byte 0x9a ; .long y ; .word x 579 580NON_GPROF_ENTRY(sigcode) 581 call SIGF_HANDLER(%esp) 582 lea SIGF_SC(%esp),%eax /* scp (the call may have clobbered the */ 583 /* copy at 8(%esp)) */ 584 pushl %eax 585 pushl %eax /* junk to fake return address */ 586 movl $103,%eax /* XXX sigreturn() */ 587 LCALL(0x7,0) /* enter kernel with args on stack */ 588 hlt /* never gets here */ 589 590 .globl _szsigcode 591_szsigcode: 592 .long _szsigcode-_sigcode 593