locore.s revision 2512
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 1.25 1994/09/05 05:20:29 davidg 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 movl 4(%esp),%eax 160 movl %eax,_boothowto-KERNBASE 161 movl 8(%esp),%eax 162 movl %eax,_bootdev-KERNBASE 163 movl 12(%esp),%eax 164 movl %eax,_cyloffset-KERNBASE 165 movl 16(%esp),%eax 166 addl $KERNBASE,%eax 167 movl %eax,_esym-KERNBASE 168#ifdef DISKLESS /* Copy diskless structure */ 169 movl _nfs_diskless_size-KERNBASE,%ecx 170 movl 20(%esp),%esi 171 movl $(_nfs_diskless-KERNBASE),%edi 172 cld 173 rep 174 movsb 175#endif 176 177 /* Find out our CPU type. */ 178 179 /* Try to toggle alignment check flag; does not exist on 386. */ 180 pushfl 181 popl %eax 182 movl %eax,%ecx 183 orl $PSL_AC,%eax 184 pushl %eax 185 popfl 186 pushfl 187 popl %eax 188 xorl %ecx,%eax 189 andl $PSL_AC,%eax 190 pushl %ecx 191 popfl 192 193 testl %eax,%eax 194 jnz 1f 195 movl $CPU_386,_cpu-KERNBASE 196 jmp 2f 197 1981: /* Try to toggle identification flag; does not exist on early 486s. */ 199 pushfl 200 popl %eax 201 movl %eax,%ecx 202 xorl $PSL_ID,%eax 203 pushl %eax 204 popfl 205 pushfl 206 popl %eax 207 xorl %ecx,%eax 208 andl $PSL_ID,%eax 209 pushl %ecx 210 popfl 211 212 testl %eax,%eax 213 jnz 1f 214 movl $CPU_486,_cpu-KERNBASE 215 216 /* check for Cyrix 486DLC -- based on check routine */ 217 /* documented in "Cx486SLC/e SMM Programmer's Guide" */ 218 xorw %dx,%dx 219 cmpw %dx,%dx # set flags to known state 220 pushfw 221 popw %cx # store flags in ecx 222 movw $0xffff,%ax 223 movw $0x0004,%bx 224 divw %bx 225 pushfw 226 popw %ax 227 andw $0x08d5,%ax # mask off important bits 228 andw $0x08d5,%cx 229 cmpw %ax,%cx 230 231 jnz 2f # if flags changed, Intel chip 232 233 movl $CPU_486DLC,_cpu-KERNBASE # set CPU value for Cyrix 234 movl $0x69727943,_cpu_vendor-KERNBASE # store vendor string 235 movw $0x0078,_cpu_vendor-KERNBASE+4 236 237 invd # Start with guaranteed clean cache 238 /* Disable caching of the ISA hole only. */ 239 movb $CCR0,%al # Configuration Register index (CCR0) 240 outb %al,$0x22 241 inb $0x23,%al 242 orb $CCR0_NC1,%al 243 outb %al,$0x23 244 invd 245 jmp 2f 246 2471: /* Use the `cpuid' instruction. */ 248 xorl %eax,%eax 249 .byte 0x0f,0xa2 # cpuid 0 250 movl %ebx,_cpu_vendor-KERNBASE # store vendor string 251 movl %edx,_cpu_vendor+4-KERNBASE 252 movl %ecx,_cpu_vendor+8-KERNBASE 253 movb $0,_cpu_vendor+12-KERNBASE 254 255 movl $1,%eax 256 .byte 0x0f,0xa2 # cpuid 1 257 movl %eax,_cpu_id-KERNBASE # store cpu_id 258 rorl $8,%eax # extract family type 259 andl $15,%eax 260 cmpl $5,%eax 261 jae 1f 262 263 /* less than Pentium; must be 486 */ 264 movl $CPU_486,_cpu-KERNBASE 265 jmp 2f 266 2671: movl $CPU_586,_cpu-KERNBASE 2682: 269 270 /* 271 * Finished with old stack; load new %esp now instead of later so 272 * we can trace this code without having to worry about the trace 273 * trap clobbering the memory test or the zeroing of the bss+bootstrap 274 * page tables. 275 * 276 * XXX - wdboot clears the bss after testing that this is safe. 277 * This is too wasteful - memory below 640K is scarce. The boot 278 * program should check: 279 * text+data <= &stack_variable - more_space_for_stack 280 * text+data+bss+pad+space_for_page_tables <= end_of_memory 281 * Oops, the gdt is in the carcass of the boot program so clearing 282 * the rest of memory is still not possible. 283 */ 284 movl $tmpstk-KERNBASE,%esp /* bootstrap stack end location */ 285 286/* 287 * Virtual address space of kernel: 288 * 289 * text | data | bss | [syms] | page dir | proc0 kernel stack | usr stk map | Sysmap 290 * pages: 1 UPAGES (2) 1 NKPT (7) 291 */ 292 293/* find end of kernel image */ 294 movl $_end-KERNBASE,%ecx 295 addl $NBPG-1,%ecx /* page align up */ 296 andl $~(NBPG-1),%ecx 297 movl %ecx,%esi /* esi = start of free memory */ 298 movl %ecx,_KERNend-KERNBASE /* save end of kernel */ 299 300/* clear bss */ 301 movl $_edata-KERNBASE,%edi 302 subl %edi,%ecx /* get amount to clear */ 303 xorl %eax,%eax /* specify zero fill */ 304 cld 305 rep 306 stosb 307 308/* 309 * The value in esi is both the end of the kernel bss and a pointer to 310 * the kernel page directory, and is used by the rest of locore to build 311 * the tables. 312 * esi + 1(page dir) + 2(UPAGES) + 1(p0stack) + NKPT(number of kernel 313 * page table pages) is then passed on the stack to init386(first) as 314 * the value first. esi should ALWAYS be page aligned!! 315 */ 316 movl %esi,%ecx /* Get current first availiable address */ 317 318/* clear pagetables, page directory, stack, etc... */ 319 movl %esi,%edi /* base (page directory) */ 320 movl $((1+UPAGES+1+NKPT)*NBPG),%ecx /* amount to clear */ 321 xorl %eax,%eax /* specify zero fill */ 322 cld 323 rep 324 stosb 325 326/* physical address of Idle proc/kernel page directory */ 327 movl %esi,_IdlePTD-KERNBASE 328 329/* 330 * fillkpt 331 * eax = (page frame address | control | status) == pte 332 * ebx = address of page table 333 * ecx = how many pages to map 334 */ 335#define fillkpt \ 3361: movl %eax,(%ebx) ; \ 337 addl $NBPG,%eax ; /* increment physical address */ \ 338 addl $4,%ebx ; /* next pte */ \ 339 loop 1b ; 340 341/* 342 * Map Kernel 343 * 344 * First step - build page tables 345 */ 346#if defined (KGDB) || defined (BDE_DEBUGGER) 347 movl _KERNend-KERNBASE,%ecx /* this much memory, */ 348 shrl $PGSHIFT,%ecx /* for this many PTEs */ 349#ifdef BDE_DEBUGGER 350 cmpl $0xa0,%ecx /* XXX - cover debugger pages */ 351 jae 1f 352 movl $0xa0,%ecx 3531: 354#endif /* BDE_DEBUGGER */ 355 movl $PG_V|PG_KW,%eax /* kernel R/W, valid */ 356 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 357 movl %ebx,_KPTphys-KERNBASE /* save in global */ 358 fillkpt 359 360#else /* !KGDB && !BDE_DEBUGGER */ 361 /* write protect kernel text (doesn't do a thing for 386's - only 486's) */ 362 movl $_etext-KERNBASE,%ecx /* get size of text */ 363 shrl $PGSHIFT,%ecx /* for this many PTEs */ 364 movl $PG_V|PG_KR,%eax /* specify read only */ 365 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 366 movl %ebx,_KPTphys-KERNBASE /* save in global */ 367 fillkpt 368 369 /* data and bss are r/w */ 370 andl $PG_FRAME,%eax /* strip to just addr of bss */ 371 movl _KERNend-KERNBASE,%ecx /* calculate size */ 372 subl %eax,%ecx 373 shrl $PGSHIFT,%ecx 374 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 375 fillkpt 376#endif /* KGDB || BDE_DEBUGGER */ 377 378/* now initialize the page dir, upages, p0stack PT, and page tables */ 379 380 movl $(1+UPAGES+1+NKPT),%ecx /* number of PTEs */ 381 movl %esi,%eax /* phys address of PTD */ 382 andl $PG_FRAME,%eax /* convert to PFN, should be a NOP */ 383 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 384 movl %esi,%ebx /* calculate pte offset to ptd */ 385 shrl $PGSHIFT-2,%ebx 386 addl %esi,%ebx /* address of page directory */ 387 addl $((1+UPAGES+1)*NBPG),%ebx /* offset to kernel page tables */ 388 fillkpt 389 390/* map I/O memory map */ 391 392 movl _KPTphys-KERNBASE,%ebx /* base of kernel page tables */ 393 lea (0xa0 * PTESIZE)(%ebx),%ebx /* hardwire ISA hole at KERNBASE + 0xa0000 */ 394 movl $0x100-0xa0,%ecx /* for this many pte s, */ 395 movl $(0xa0000|PG_V|PG_KW|PG_N),%eax /* valid, kernel read/write, non-cacheable */ 396 movl %ebx,_atdevphys-KERNBASE /* save phys addr of ptes */ 397 fillkpt 398 399 /* map proc 0's kernel stack into user page table page */ 400 401 movl $UPAGES,%ecx /* for this many pte s, */ 402 lea (1*NBPG)(%esi),%eax /* physical address in proc 0 */ 403 lea (KERNBASE)(%eax),%edx /* change into virtual addr */ 404 movl %edx,_proc0paddr-KERNBASE /* save VA for proc 0 init */ 405 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 406 lea ((1+UPAGES)*NBPG)(%esi),%ebx /* addr of stack page table in proc 0 */ 407 addl $(KSTKPTEOFF * PTESIZE),%ebx /* offset to kernel stack PTE */ 408 fillkpt 409 410/* 411 * Initialize kernel page table directory 412 */ 413 /* install a pde for temporary double map of bottom of VA */ 414 movl _KPTphys-KERNBASE,%eax 415 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 416 movl %eax,(%esi) /* which is where temp maps! */ 417 418 /* initialize kernel pde's */ 419 movl $(NKPT),%ecx /* for this many PDEs */ 420 lea (KPTDI*PDESIZE)(%esi),%ebx /* offset of pde for kernel */ 421 fillkpt 422 423 /* install a pde recursively mapping page directory as a page table! */ 424 movl %esi,%eax /* phys address of ptd in proc 0 */ 425 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 426 movl %eax,PTDPTDI*PDESIZE(%esi) /* which is where PTmap maps! */ 427 428 /* install a pde to map kernel stack for proc 0 */ 429 lea ((1+UPAGES)*NBPG)(%esi),%eax /* physical address of pt in proc 0 */ 430 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 431 movl %eax,KSTKPTDI*PDESIZE(%esi) /* which is where kernel stack maps! */ 432 433#ifdef BDE_DEBUGGER 434 /* copy and convert stuff from old gdt and idt for debugger */ 435 436 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */ 437 jne 1f 438 movb $1,_bdb_exists-KERNBASE 4391: 440 pushal 441 subl $2*6,%esp 442 443 sgdt (%esp) 444 movl 2(%esp),%esi /* base address of current gdt */ 445 movl $_gdt-KERNBASE,%edi 446 movl %edi,2(%esp) 447 movl $8*18/4,%ecx 448 cld 449 rep /* copy gdt */ 450 movsl 451 movl $_gdt-KERNBASE,-8+2(%edi) /* adjust gdt self-ptr */ 452 movb $0x92,-8+5(%edi) 453 454 sidt 6(%esp) 455 movl 6+2(%esp),%esi /* base address of current idt */ 456 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */ 457 movw 8(%esi),%ax 458 movl %eax,bdb_dbg_ljmp+1-KERNBASE /* ... immediate offset ... */ 459 movl 8+2(%esi),%eax 460 movw %ax,bdb_dbg_ljmp+5-KERNBASE /* ... and selector for ljmp */ 461 movl 24+4(%esi),%eax /* same for bpt descriptor */ 462 movw 24(%esi),%ax 463 movl %eax,bdb_bpt_ljmp+1-KERNBASE 464 movl 24+2(%esi),%eax 465 movw %ax,bdb_bpt_ljmp+5-KERNBASE 466 467 movl $_idt-KERNBASE,%edi 468 movl %edi,6+2(%esp) 469 movl $8*4/4,%ecx 470 cld 471 rep /* copy idt */ 472 movsl 473 474 lgdt (%esp) 475 lidt 6(%esp) 476 477 addl $2*6,%esp 478 popal 479#endif /* BDE_DEBUGGER */ 480 481 /* load base of page directory and enable mapping */ 482 movl %esi,%eax /* phys address of ptd in proc 0 */ 483 orl $I386_CR3PAT,%eax 484 movl %eax,%cr3 /* load ptd addr into mmu */ 485 movl %cr0,%eax /* get control word */ 486 orl $CR0_PE|CR0_PG,%eax /* enable paging */ 487 movl %eax,%cr0 /* and let's page NOW! */ 488 489 pushl $begin /* jump to high mem */ 490 ret 491 492begin: /* now running relocated at KERNBASE where the system is linked to run */ 493 494 .globl _Crtat /* XXX - locore should not know about */ 495 movl _Crtat,%eax /* variables of device drivers (pccons)! */ 496 subl $(KERNBASE+0xA0000),%eax 497 movl _atdevphys,%edx /* get pte PA */ 498 subl _KPTphys,%edx /* remove base of ptes, now have phys offset */ 499 shll $PGSHIFT-2,%edx /* corresponding to virt offset */ 500 addl $KERNBASE,%edx /* add virtual base */ 501 movl %edx,_atdevbase 502 addl %eax,%edx 503 movl %edx,_Crtat 504 505 /* set up bootstrap stack - 48 bytes */ 506 movl $_kstack+UPAGES*NBPG-4*12,%esp /* bootstrap stack end location */ 507 xorl %eax,%eax /* mark end of frames */ 508 movl %eax,%ebp 509 movl _proc0paddr,%eax 510 movl %esi,PCB_CR3(%eax) 511 512#ifdef BDE_DEBUGGER 513 /* relocate debugger gdt entries */ 514 515 movl $_gdt+8*9,%eax /* adjust slots 9-17 */ 516 movl $9,%ecx 517reloc_gdt: 518 movb $KERNBASE>>24,7(%eax) /* top byte of base addresses, was 0, */ 519 addl $8,%eax /* now KERNBASE>>24 */ 520 loop reloc_gdt 521 522 cmpl $0,_bdb_exists 523 je 1f 524 int $3 5251: 526#endif /* BDE_DEBUGGER */ 527 528 /* 529 * Skip over the page tables and the kernel stack 530 */ 531 lea ((1+UPAGES+1+NKPT)*NBPG)(%esi),%esi 532 533 pushl %esi /* value of first for init386(first) */ 534 call _init386 /* wire 386 chip for unix operation */ 535 popl %esi 536 537 .globl __ucodesel,__udatasel 538 539 pushl $0 /* unused */ 540 pushl __udatasel /* ss */ 541 pushl $0 /* esp - filled in by execve() */ 542 pushl $PSL_USERSET /* eflags (ring 0, int enab) */ 543 pushl __ucodesel /* cs */ 544 pushl $0 /* eip - filled in by execve() */ 545 subl $(12*4),%esp /* space for rest of registers */ 546 547 pushl %esp /* call main with frame pointer */ 548 call _main /* autoconfiguration, mountroot etc */ 549 550 addl $(13*4),%esp /* back to a frame we can return with */ 551 552 /* 553 * now we've run main() and determined what cpu-type we are, we can 554 * enable WP mode on i486 cpus and above. 555 */ 556#if defined(I486_CPU) || defined(I586_CPU) 557 cmpl $CPUCLASS_386,_cpu_class 558 je 1f 559 movl %cr0,%eax /* get control word */ 560 orl $CR0_WP,%eax /* enable write protect for all modes */ 561 movl %eax,%cr0 /* and do it */ 562#endif 563 /* 564 * on return from main(), we are process 1 565 * set up address space and stack so that we can 'return' to user mode 566 */ 5671: 568 movl __ucodesel,%eax 569 movl __udatasel,%ecx 570 571 movl %cx,%ds 572 movl %cx,%es 573 movl %ax,%fs /* double map cs to fs */ 574 movl %cx,%gs /* and ds to gs */ 575 iret /* goto user! */ 576 577#define LCALL(x,y) .byte 0x9a ; .long y ; .word x 578 579NON_GPROF_ENTRY(sigcode) 580 call SIGF_HANDLER(%esp) 581 lea SIGF_SC(%esp),%eax /* scp (the call may have clobbered the */ 582 /* copy at 8(%esp)) */ 583 pushl %eax 584 pushl %eax /* junk to fake return address */ 585 movl $103,%eax /* XXX sigreturn() */ 586 LCALL(0x7,0) /* enter kernel with args on stack */ 587 hlt /* never gets here */ 588 589 .globl _szsigcode 590_szsigcode: 591 .long _szsigcode-_sigcode 592