locore.s revision 757
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 * $Id$ 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 50#include "assym.s" /* system definitions */ 51#include "machine/psl.h" /* processor status longword defs */ 52#include "machine/pte.h" /* page table entry definitions */ 53 54#include "errno.h" /* error return codes */ 55 56#include "machine/specialreg.h" /* x86 special registers */ 57#include "i386/isa/debug.h" /* BDE debugging macros */ 58#include "machine/cputypes.h" /* x86 cpu type definitions */ 59 60#include "syscall.h" /* system call numbers */ 61 62#include "machine/asmacros.h" /* miscellaneous asm macros */ 63 64/* 65 * XXX 66 * 67 * Note: This version greatly munged to avoid various assembler errors 68 * that may be fixed in newer versions of gas. Perhaps newer versions 69 * will have more pleasant appearance. 70 */ 71 72/* 73 * PTmap is recursive pagemap at top of virtual address space. 74 * Within PTmap, the page directory can be found (third indirection). 75 */ 76 .globl _PTmap,_PTD,_PTDpde,_Sysmap 77 .set _PTmap,PTDPTDI << PDRSHIFT 78 .set _PTD,_PTmap + (PTDPTDI * NBPG) 79 .set _PTDpde,_PTD + (PTDPTDI * PDESIZE) 80 81/* Sysmap is the base address of the kernel page tables */ 82 .set _Sysmap,_PTmap + (KPTDI * NBPG) 83 84/* 85 * APTmap, APTD is the alternate recursive pagemap. 86 * It's used when modifying another process's page tables. 87 */ 88 .globl _APTmap,_APTD,_APTDpde 89 .set _APTmap,APTDPTDI << PDRSHIFT 90 .set _APTD,_APTmap + (APTDPTDI * NBPG) 91 .set _APTDpde,_PTD + (APTDPTDI * PDESIZE) 92 93/* 94 * Access to each processes kernel stack is via a region of 95 * per-process address space (at the beginning), immediatly above 96 * the user process stack. 97 */ 98 .set _kstack,USRSTACK 99 .globl _kstack 100 101/* 102 * Globals 103 */ 104 .data 105 .globl _esym 106_esym: .long 0 /* ptr to end of syms */ 107 108 .globl _boothowto,_bootdev,_curpcb 109 110 .globl _cpu,_cold,_atdevbase 111_cpu: .long 0 /* are we 386, 386sx, or 486 */ 112_cold: .long 1 /* cold till we are not */ 113_atdevbase: .long 0 /* location of start of iomem in virtual */ 114_atdevphys: .long 0 /* location of device mapping ptes (phys) */ 115 116 .globl _KERNend 117_KERNend: .long 0 /* phys addr end of kernel (just after bss) */ 118 119 .globl _IdlePTD,_KPTphys 120_IdlePTD: .long 0 /* phys addr of kernel PTD */ 121_KPTphys: .long 0 /* phys addr of kernel page tables */ 122 123 .globl _cyloffset 124_cyloffset: .long 0 /* cylinder offset from boot blocks */ 125 126 .globl _proc0paddr 127_proc0paddr: .long 0 /* address of proc 0 address space */ 128 129#ifdef BDE_DEBUGGER 130 .globl _bdb_exists /* flag to indicate BDE debugger is available */ 131 .long 0 132#endif 133 134 .globl tmpstk 135 .space 512 136tmpstk: 137 138 139/* 140 * System Initialization 141 */ 142 .text 143 144/* 145 * btext: beginning of text section. 146 * Also the entry point (jumped to directly from the boot blocks). 147 */ 148ENTRY(btext) 149 movw $0x1234,0x472 /* warm boot */ 150 jmp 1f 151 .space 0x500 /* skip over warm boot shit */ 152 153 /* 154 * pass parameters on stack (howto, bootdev, unit, cyloffset, esym) 155 * note: (%esp) is return address of boot 156 * ( if we want to hold onto /boot, it's physical %esp up to _end) 157 */ 158 159 1: 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 168 169 /* find out our CPU type. */ 170 pushfl 171 popl %eax 172 movl %eax,%ecx 173 xorl $0x40000,%eax 174 pushl %eax 175 popfl 176 pushfl 177 popl %eax 178 xorl %ecx,%eax 179 shrl $18,%eax 180 andl $1,%eax 181 push %ecx 182 popfl 183 184 cmpl $0,%eax 185 jne 1f 186 movl $CPU_386,_cpu-KERNBASE 187 jmp 2f 1881: movl $CPU_486,_cpu-KERNBASE 1892: 190 191 /* 192 * Finished with old stack; load new %esp now instead of later so 193 * we can trace this code without having to worry about the trace 194 * trap clobbering the memory test or the zeroing of the bss+bootstrap 195 * page tables. 196 * 197 * XXX - wdboot clears the bss after testing that this is safe. 198 * This is too wasteful - memory below 640K is scarce. The boot 199 * program should check: 200 * text+data <= &stack_variable - more_space_for_stack 201 * text+data+bss+pad+space_for_page_tables <= end_of_memory 202 * Oops, the gdt is in the carcass of the boot program so clearing 203 * the rest of memory is still not possible. 204 */ 205 movl $tmpstk-KERNBASE,%esp /* bootstrap stack end location */ 206 207/* 208 * Virtual address space of kernel: 209 * 210 * text | data | bss | [syms] | page dir | proc0 kernel stack | usr stk map | Sysmap 211 * pages: 1 UPAGES (2) 1 NKPDE (7) 212 */ 213 214/* find end of kernel image */ 215 movl $_end-KERNBASE,%ecx 216 addl $NBPG-1,%ecx /* page align up */ 217 andl $~(NBPG-1),%ecx 218 movl %ecx,%esi /* esi=start of tables */ 219 movl %ecx,_KERNend-KERNBASE /* save end of kernel */ 220 221/* clear bss */ 222 movl $_edata-KERNBASE,%edi 223 subl %edi,%ecx /* get mount to clear */ 224 xorl %eax,%eax /* specify zero fill */ 225 cld 226 rep 227 stosb 228 229/* 230 * If we are loaded at 0x0 check to see if we have space for the 231 * page dir/tables and stack area after the kernel and before the 640K 232 * ISA memory hole. If we do not have space relocate the page directory, 233 * UPAGES, proc 0 stack, and page table pages to start at 1MB. The value 234 * that ends up in esi, which points to the kernel page directory, is 235 * used by the rest of locore to build the tables. 236 * esi + 1(page dir) + 2(UPAGES) + 1(p0stack) + NKPDE(number of kernel 237 * page table pages) is then passed on the stack to init386(first) as 238 * the value first. esi should ALWAYS be page aligned!! 239 */ 240 movl %esi,%ecx /* Get current first availiable address */ 241 cmpl $0x100000,%ecx /* Lets see if we are already above 1MB */ 242 jge 1f /* yep, don't need to check for room */ 243 addl $((1+UPAGES+1+NKPDE)*NBPG),%ecx /* XXX the 4 is for kstack */ 244 /* space for kstack, PTD and PTE's */ 245 cmpl $(640*1024),%ecx /* see if it fits in low memory */ 246 jle 1f /* yep, don't need to relocate it */ 247 movl $0x100000,%esi /* won't fit, so start it at 1MB */ 2481: 249 250/* clear pagetables, page directory, stack, etc... */ 251 movl %esi,%edi /* base (page directory) */ 252 movl $((1+UPAGES+1+NKPDE)*NBPG),%ecx /* amount to clear */ 253 xorl %eax,%eax /* specify zero fill */ 254 cld 255 rep 256 stosb 257 258/* physical address of Idle proc/kernel page directory */ 259 movl %esi,_IdlePTD-KERNBASE 260 261/* 262 * fillkpt 263 * eax = (page frame address | control | status) == pte 264 * ebx = address of page table 265 * ecx = how many pages to map 266 */ 267#define fillkpt \ 2681: movl %eax,(%ebx) ; \ 269 addl $NBPG,%eax ; /* increment physical address */ \ 270 addl $4,%ebx ; /* next pte */ \ 271 loop 1b ; 272 273/* 274 * Map Kernel 275 * 276 * First step - build page tables 277 */ 278#if defined (KGDB) || defined (BDE_DEBUGGER) 279 movl _KERNend-KERNBASE,%ecx /* this much memory, */ 280 shrl $PGSHIFT,%ecx /* for this many PTEs */ 281#ifdef BDE_DEBUGGER 282 cmpl $0xa0,%ecx /* XXX - cover debugger pages */ 283 jae 1f 284 movl $0xa0,%ecx 2851: 286#endif /* BDE_DEBUGGER */ 287 movl $PG_V|PG_KW,%eax /* having these bits set, */ 288 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 289 movl %ebx,_KPTphys-KERNBASE /* save in global */ 290 fillkpt 291 292#else /* !KGDB && !BDE_DEBUGGER */ 293 /* write protect kernel text (doesn't do a thing for 386's - only 486's) */ 294 movl $_etext-KERNBASE,%ecx /* get size of text */ 295 shrl $PGSHIFT,%ecx /* for this many PTEs */ 296 movl $PG_V|PG_KR,%eax /* specify read only */ 297 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 298 movl %ebx,_KPTphys-KERNBASE /* save in global */ 299 fillkpt 300 301 /* data and bss are r/w */ 302 andl $PG_FRAME,%eax /* strip to just addr of bss */ 303 movl _KERNend-KERNBASE,%ecx /* calculate size */ 304 subl %eax,%ecx 305 shrl $PGSHIFT,%ecx 306 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 307 fillkpt 308#endif 309 310/* now initialize the page dir, upages, p0stack PT, and page tables */ 311 312 movl $(1+UPAGES+1+NKPDE),%ecx /* number of PTEs */ 313 movl %esi,%eax /* phys address of PTD */ 314 andl $PG_FRAME,%eax /* convert to PFN, should be a NOP */ 315 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 316 movl %esi,%ebx /* calculate pte offset to ptd */ 317 shrl $PGSHIFT-2,%ebx 318 addl %esi,%ebx /* address of page directory */ 319 addl $((1+UPAGES+1)*NBPG),%ebx /* offset to kernel page tables */ 320 fillkpt 321 322/* map I/O memory map */ 323 324 movl _KPTphys-KERNBASE,%ebx /* base of kernel page tables */ 325 lea (0xa0 * PTESIZE)(%ebx),%ebx /* hardwire ISA hole at KERNBASE + 0xa0000 */ 326 movl $0x100-0xa0,%ecx /* for this many pte s, */ 327 movl $(0xa0000|PG_V|PG_KW),%eax /* valid, kernel read/write */ 328 movl %ebx,_atdevphys-KERNBASE /* save phys addr of ptes */ 329 fillkpt 330 331 /* map proc 0's kernel stack into user page table page */ 332 333 movl $UPAGES,%ecx /* for this many pte s, */ 334 lea (1*NBPG)(%esi),%eax /* physical address in proc 0 */ 335 lea (KERNBASE)(%eax),%edx /* change into virtual addr */ 336 movl %edx,_proc0paddr-KERNBASE /* save VA for proc 0 init */ 337 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 338 lea ((1+UPAGES)*NBPG)(%esi),%ebx /* addr of stack page table in proc 0 */ 339 addl $(KSTKPTEOFF * PTESIZE),%ebx /* offset to kernel stack PTE */ 340 fillkpt 341 342/* 343 * Initialize kernel page table directory 344 */ 345 /* install a pde for temporary double map of bottom of VA */ 346 movl _KPTphys-KERNBASE,%eax 347 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 348 movl %eax,(%esi) /* which is where temp maps! */ 349 350 /* initialize kernel pde's */ 351 movl $(NKPDE),%ecx /* for this many PDEs */ 352 lea (KPTDI*PDESIZE)(%esi),%ebx /* offset of pde for kernel */ 353 fillkpt 354 355 /* install a pde recursively mapping page directory as a page table! */ 356 movl %esi,%eax /* phys address of ptd in proc 0 */ 357 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 358 movl %eax,PTDPTDI*PDESIZE(%esi) /* which is where PTmap maps! */ 359 360 /* install a pde to map kernel stack for proc 0 */ 361 lea ((1+UPAGES)*NBPG)(%esi),%eax /* physical address of pt in proc 0 */ 362 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 363 movl %eax,KSTKPTDI*PDESIZE(%esi) /* which is where kernel stack maps! */ 364 365#ifdef BDE_DEBUGGER 366 /* copy and convert stuff from old gdt and idt for debugger */ 367 368 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */ 369 jne 1f 370 movb $1,_bdb_exists-KERNBASE 3711: 372 pushal 373 subl $2*6,%esp 374 375 sgdt (%esp) 376 movl 2(%esp),%esi /* base address of current gdt */ 377 movl $_gdt-KERNBASE,%edi 378 movl %edi,2(%esp) 379 movl $8*18/4,%ecx 380 rep /* copy gdt */ 381 movsl 382 movl $_gdt-KERNBASE,-8+2(%edi) /* adjust gdt self-ptr */ 383 movb $0x92,-8+5(%edi) 384 385 sidt 6(%esp) 386 movl 6+2(%esp),%esi /* base address of current idt */ 387 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */ 388 movw 8(%esi),%ax 389 movl %eax,bdb_dbg_ljmp+1-KERNBASE /* ... immediate offset ... */ 390 movl 8+2(%esi),%eax 391 movw %ax,bdb_dbg_ljmp+5-KERNBASE /* ... and selector for ljmp */ 392 movl 24+4(%esi),%eax /* same for bpt descriptor */ 393 movw 24(%esi),%ax 394 movl %eax,bdb_bpt_ljmp+1-KERNBASE 395 movl 24+2(%esi),%eax 396 movw %ax,bdb_bpt_ljmp+5-KERNBASE 397 398 movl $_idt-KERNBASE,%edi 399 movl %edi,6+2(%esp) 400 movl $8*4/4,%ecx 401 rep /* copy idt */ 402 movsl 403 404 lgdt (%esp) 405 lidt 6(%esp) 406 407 addl $2*6,%esp 408 popal 409#endif 410 411 /* load base of page directory and enable mapping */ 412 movl %esi,%eax /* phys address of ptd in proc 0 */ 413 orl $I386_CR3PAT,%eax 414 movl %eax,%cr3 /* load ptd addr into mmu */ 415 movl %cr0,%eax /* get control word */ 416/* 417 * XXX it is now safe to always (attempt to) set CR0_WP and to set up 418 * the page tables assuming it works, so USE_486_WRITE_PROTECT will go 419 * away. The special 386 PTE checking needs to be conditional on 420 * whatever distingiushes 486-only kernels from 386-486 kernels. 421 */ 422#ifdef USE_486_WRITE_PROTECT 423 orl $CR0_PE|CR0_PG|CR0_WP,%eax /* enable paging */ 424#else 425 orl $CR0_PE|CR0_PG,%eax /* enable paging */ 426#endif 427 movl %eax,%cr0 /* and let's page NOW! */ 428 429 pushl $begin /* jump to high mem */ 430 ret 431 432begin: /* now running relocated at KERNBASE where the system is linked to run */ 433 434 .globl _Crtat /* XXX - locore should not know about */ 435 movl _Crtat,%eax /* variables of device drivers (pccons)! */ 436 subl $(KERNBASE+0xA0000),%eax 437 movl _atdevphys,%edx /* get pte PA */ 438 subl _KPTphys,%edx /* remove base of ptes, now have phys offset */ 439 shll $PGSHIFT-2,%edx /* corresponding to virt offset */ 440 addl $KERNBASE,%edx /* add virtual base */ 441 movl %edx,_atdevbase 442 addl %eax,%edx 443 movl %edx,_Crtat 444 445 /* set up bootstrap stack - 48 bytes */ 446 movl $_kstack+UPAGES*NBPG-4*12,%esp /* bootstrap stack end location */ 447 xorl %eax,%eax /* mark end of frames */ 448 movl %eax,%ebp 449 movl _proc0paddr,%eax 450 movl %esi,PCB_CR3(%eax) 451 452#ifdef BDE_DEBUGGER 453 /* relocate debugger gdt entries */ 454 455 movl $_gdt+8*9,%eax /* adjust slots 9-17 */ 456 movl $9,%ecx 457reloc_gdt: 458 movb $0xfe,7(%eax) /* top byte of base addresses, was 0, */ 459 addl $8,%eax /* now KERNBASE>>24 */ 460 loop reloc_gdt 461 462 cmpl $0,_bdb_exists 463 je 1f 464 int $3 4651: 466#endif 467 468 /* 469 * Skip over the page tables and the kernel stack 470 */ 471 lea ((1+UPAGES+1+NKPDE)*NBPG)(%esi),%esi 472 473 pushl %esi /* value of first for init386(first) */ 474 call _init386 /* wire 386 chip for unix operation */ 475 476 movl $0,_PTD 477 call _main /* autoconfiguration, mountroot etc */ 478 popl %esi 479 480 /* 481 * now we've run main() and determined what cpu-type we are, we can 482 * enable WP mode on i486 cpus and above. 483 * on return from main(), we are process 1 484 * set up address space and stack so that we can 'return' to user mode 485 */ 486 487 .globl __ucodesel,__udatasel 488 movl __ucodesel,%eax 489 movl __udatasel,%ecx 490 /* build outer stack frame */ 491 pushl %ecx /* user ss */ 492 pushl $USRSTACK /* user esp */ 493 pushl %eax /* user cs */ 494 pushl $0 /* user ip */ 495 movl %cx,%ds 496 movl %cx,%es 497 movl %ax,%fs /* double map cs to fs */ 498 movl %cx,%gs /* and ds to gs */ 499 lret /* goto user! */ 500 501 pushl $lretmsg1 /* "should never get here!" */ 502 call _panic 503lretmsg1: 504 .asciz "lret: toinit\n" 505 506 507#define LCALL(x,y) .byte 0x9a ; .long y; .word x 508/* 509 * Icode is copied out to process 1 and executed in user mode: 510 * execve("/sbin/init", argv, envp); exit(0); 511 * If the execve fails, process 1 exits and the system panics. 512 */ 513NON_GPROF_ENTRY(icode) 514 pushl $0 /* envp for execve() */ 515 516# pushl $argv-_icode /* can't do this 'cos gas 1.38 is broken */ 517 movl $argv,%eax 518 subl $_icode,%eax 519 pushl %eax /* argp for execve() */ 520 521# pushl $init-_icode 522 movl $init,%eax 523 subl $_icode,%eax 524 pushl %eax /* fname for execve() */ 525 526 pushl %eax /* dummy return address */ 527 528 movl $SYS_execve,%eax 529 LCALL(0x7,0x0) 530 531 /* exit if something botches up in the above execve() */ 532 pushl %eax /* execve failed, the errno will do for an */ 533 /* exit code because errnos are < 128 */ 534 pushl %eax /* dummy return address */ 535 movl $SYS_exit,%eax 536 LCALL(0x7,0x0) 537 538init: 539 .asciz "/sbin/init" 540 ALIGN_DATA 541argv: 542 .long init+6-_icode /* argv[0] = "init" ("/sbin/init" + 6) */ 543 .long eicode-_icode /* argv[1] follows icode after copyout */ 544 .long 0 545eicode: 546 547 .globl _szicode 548_szicode: 549 .long _szicode-_icode 550 551NON_GPROF_ENTRY(sigcode) 552 call SIGF_HANDLER(%esp) 553 lea SIGF_SC(%esp),%eax /* scp (the call may have clobbered the */ 554 /* copy at 8(%esp)) */ 555 pushl %eax 556 pushl %eax /* junk to fake return address */ 557 movl $103,%eax /* XXX sigreturn() */ 558 LCALL(0x7,0) /* enter kernel with args on stack */ 559 hlt /* never gets here */ 560 561 .globl _szsigcode 562_szsigcode: 563 .long _szsigcode-_sigcode 564