locore.s revision 975
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 1.12 1994/01/14 16:23:33 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 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_bde_exists: .long 0 132#endif 133 134 .globl tmpstk 135 .space 0x1000 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#ifdef DISKLESS /* Copy diskless structure */ 169 movl _nfs_diskless_size-KERNBASE,%ecx 170 movl 20(%esp),%esi 171 movl $(_nfs_diskless-KERNBASE),%edi 172 rep 173 movsb 174#endif 175 176 /* find out our CPU type. */ 177 pushfl 178 popl %eax 179 movl %eax,%ecx 180 xorl $0x40000,%eax 181 pushl %eax 182 popfl 183 pushfl 184 popl %eax 185 xorl %ecx,%eax 186 shrl $18,%eax 187 andl $1,%eax 188 push %ecx 189 popfl 190 191 cmpl $0,%eax 192 jne 1f 193 movl $CPU_386,_cpu-KERNBASE 194 jmp 2f 1951: movl $CPU_486,_cpu-KERNBASE 1962: 197 198 /* 199 * Finished with old stack; load new %esp now instead of later so 200 * we can trace this code without having to worry about the trace 201 * trap clobbering the memory test or the zeroing of the bss+bootstrap 202 * page tables. 203 * 204 * XXX - wdboot clears the bss after testing that this is safe. 205 * This is too wasteful - memory below 640K is scarce. The boot 206 * program should check: 207 * text+data <= &stack_variable - more_space_for_stack 208 * text+data+bss+pad+space_for_page_tables <= end_of_memory 209 * Oops, the gdt is in the carcass of the boot program so clearing 210 * the rest of memory is still not possible. 211 */ 212 movl $tmpstk-KERNBASE,%esp /* bootstrap stack end location */ 213 214/* 215 * Virtual address space of kernel: 216 * 217 * text | data | bss | [syms] | page dir | proc0 kernel stack | usr stk map | Sysmap 218 * pages: 1 UPAGES (2) 1 NKPT (7) 219 */ 220 221/* find end of kernel image */ 222 movl $_end-KERNBASE,%ecx 223 addl $NBPG-1,%ecx /* page align up */ 224 andl $~(NBPG-1),%ecx 225 movl %ecx,%esi /* esi=start of tables */ 226 movl %ecx,_KERNend-KERNBASE /* save end of kernel */ 227 228/* clear bss */ 229 movl $_edata-KERNBASE,%edi 230 subl %edi,%ecx /* get amount to clear */ 231 xorl %eax,%eax /* specify zero fill */ 232 cld 233 rep 234 stosb 235 236/* 237 * The value in esi is both the end of the kernel bss and a pointer to 238 * the kernel page directory, and is used by the rest of locore to build 239 * the tables. 240 * esi + 1(page dir) + 2(UPAGES) + 1(p0stack) + NKPT(number of kernel 241 * page table pages) is then passed on the stack to init386(first) as 242 * the value first. esi should ALWAYS be page aligned!! 243 */ 244 movl %esi,%ecx /* Get current first availiable address */ 245 246/* clear pagetables, page directory, stack, etc... */ 247 movl %esi,%edi /* base (page directory) */ 248 movl $((1+UPAGES+1+NKPT)*NBPG),%ecx /* amount to clear */ 249 xorl %eax,%eax /* specify zero fill */ 250 cld 251 rep 252 stosb 253 254/* physical address of Idle proc/kernel page directory */ 255 movl %esi,_IdlePTD-KERNBASE 256 257/* 258 * fillkpt 259 * eax = (page frame address | control | status) == pte 260 * ebx = address of page table 261 * ecx = how many pages to map 262 */ 263#define fillkpt \ 2641: movl %eax,(%ebx) ; \ 265 addl $NBPG,%eax ; /* increment physical address */ \ 266 addl $4,%ebx ; /* next pte */ \ 267 loop 1b ; 268 269/* 270 * Map Kernel 271 * 272 * First step - build page tables 273 */ 274#if defined (KGDB) || defined (BDE_DEBUGGER) 275 movl _KERNend-KERNBASE,%ecx /* this much memory, */ 276 shrl $PGSHIFT,%ecx /* for this many PTEs */ 277#ifdef BDE_DEBUGGER 278 cmpl $0xa0,%ecx /* XXX - cover debugger pages */ 279 jae 1f 280 movl $0xa0,%ecx 2811: 282#endif /* BDE_DEBUGGER */ 283 movl $PG_V|PG_KW,%eax /* having these bits set, */ 284 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 285 movl %ebx,_KPTphys-KERNBASE /* save in global */ 286 fillkpt 287 288#else /* !KGDB && !BDE_DEBUGGER */ 289 /* write protect kernel text (doesn't do a thing for 386's - only 486's) */ 290 movl $_etext-KERNBASE,%ecx /* get size of text */ 291 shrl $PGSHIFT,%ecx /* for this many PTEs */ 292 movl $PG_V|PG_KR,%eax /* specify read only */ 293 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 294 movl %ebx,_KPTphys-KERNBASE /* save in global */ 295 fillkpt 296 297 /* data and bss are r/w */ 298 andl $PG_FRAME,%eax /* strip to just addr of bss */ 299 movl _KERNend-KERNBASE,%ecx /* calculate size */ 300 subl %eax,%ecx 301 shrl $PGSHIFT,%ecx 302 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 303 fillkpt 304#endif 305 306/* now initialize the page dir, upages, p0stack PT, and page tables */ 307 308 movl $(1+UPAGES+1+NKPT),%ecx /* number of PTEs */ 309 movl %esi,%eax /* phys address of PTD */ 310 andl $PG_FRAME,%eax /* convert to PFN, should be a NOP */ 311 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 312 movl %esi,%ebx /* calculate pte offset to ptd */ 313 shrl $PGSHIFT-2,%ebx 314 addl %esi,%ebx /* address of page directory */ 315 addl $((1+UPAGES+1)*NBPG),%ebx /* offset to kernel page tables */ 316 fillkpt 317 318/* map I/O memory map */ 319 320 movl _KPTphys-KERNBASE,%ebx /* base of kernel page tables */ 321 lea (0xa0 * PTESIZE)(%ebx),%ebx /* hardwire ISA hole at KERNBASE + 0xa0000 */ 322 movl $0x100-0xa0,%ecx /* for this many pte s, */ 323 movl $(0xa0000|PG_V|PG_KW),%eax /* valid, kernel read/write */ 324 movl %ebx,_atdevphys-KERNBASE /* save phys addr of ptes */ 325 fillkpt 326 327 /* map proc 0's kernel stack into user page table page */ 328 329 movl $UPAGES,%ecx /* for this many pte s, */ 330 lea (1*NBPG)(%esi),%eax /* physical address in proc 0 */ 331 lea (KERNBASE)(%eax),%edx /* change into virtual addr */ 332 movl %edx,_proc0paddr-KERNBASE /* save VA for proc 0 init */ 333 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 334 lea ((1+UPAGES)*NBPG)(%esi),%ebx /* addr of stack page table in proc 0 */ 335 addl $(KSTKPTEOFF * PTESIZE),%ebx /* offset to kernel stack PTE */ 336 fillkpt 337 338/* 339 * Initialize kernel page table directory 340 */ 341 /* install a pde for temporary double map of bottom of VA */ 342 movl _KPTphys-KERNBASE,%eax 343 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 344 movl %eax,(%esi) /* which is where temp maps! */ 345 346 /* initialize kernel pde's */ 347 movl $(NKPT),%ecx /* for this many PDEs */ 348 lea (KPTDI*PDESIZE)(%esi),%ebx /* offset of pde for kernel */ 349 fillkpt 350 351 /* install a pde recursively mapping page directory as a page table! */ 352 movl %esi,%eax /* phys address of ptd in proc 0 */ 353 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 354 movl %eax,PTDPTDI*PDESIZE(%esi) /* which is where PTmap maps! */ 355 356 /* install a pde to map kernel stack for proc 0 */ 357 lea ((1+UPAGES)*NBPG)(%esi),%eax /* physical address of pt in proc 0 */ 358 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 359 movl %eax,KSTKPTDI*PDESIZE(%esi) /* which is where kernel stack maps! */ 360 361#ifdef BDE_DEBUGGER 362 /* copy and convert stuff from old gdt and idt for debugger */ 363 364 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */ 365 jne 1f 366 movb $1,_bdb_exists-KERNBASE 3671: 368 pushal 369 subl $2*6,%esp 370 371 sgdt (%esp) 372 movl 2(%esp),%esi /* base address of current gdt */ 373 movl $_gdt-KERNBASE,%edi 374 movl %edi,2(%esp) 375 movl $8*18/4,%ecx 376 rep /* copy gdt */ 377 movsl 378 movl $_gdt-KERNBASE,-8+2(%edi) /* adjust gdt self-ptr */ 379 movb $0x92,-8+5(%edi) 380 381 sidt 6(%esp) 382 movl 6+2(%esp),%esi /* base address of current idt */ 383 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */ 384 movw 8(%esi),%ax 385 movl %eax,bdb_dbg_ljmp+1-KERNBASE /* ... immediate offset ... */ 386 movl 8+2(%esi),%eax 387 movw %ax,bdb_dbg_ljmp+5-KERNBASE /* ... and selector for ljmp */ 388 movl 24+4(%esi),%eax /* same for bpt descriptor */ 389 movw 24(%esi),%ax 390 movl %eax,bdb_bpt_ljmp+1-KERNBASE 391 movl 24+2(%esi),%eax 392 movw %ax,bdb_bpt_ljmp+5-KERNBASE 393 394 movl $_idt-KERNBASE,%edi 395 movl %edi,6+2(%esp) 396 movl $8*4/4,%ecx 397 rep /* copy idt */ 398 movsl 399 400 lgdt (%esp) 401 lidt 6(%esp) 402 403 addl $2*6,%esp 404 popal 405#endif 406 407 /* load base of page directory and enable mapping */ 408 movl %esi,%eax /* phys address of ptd in proc 0 */ 409 orl $I386_CR3PAT,%eax 410 movl %eax,%cr3 /* load ptd addr into mmu */ 411 movl %cr0,%eax /* get control word */ 412/* 413 * XXX it is now safe to always (attempt to) set CR0_WP and to set up 414 * the page tables assuming it works, so USE_486_WRITE_PROTECT will go 415 * away. The special 386 PTE checking needs to be conditional on 416 * whatever distingiushes 486-only kernels from 386-486 kernels. 417 */ 418#ifdef USE_486_WRITE_PROTECT 419 orl $CR0_PE|CR0_PG|CR0_WP,%eax /* enable paging */ 420#else 421 orl $CR0_PE|CR0_PG,%eax /* enable paging */ 422#endif 423 movl %eax,%cr0 /* and let's page NOW! */ 424 425 pushl $begin /* jump to high mem */ 426 ret 427 428begin: /* now running relocated at KERNBASE where the system is linked to run */ 429 430 .globl _Crtat /* XXX - locore should not know about */ 431 movl _Crtat,%eax /* variables of device drivers (pccons)! */ 432 subl $(KERNBASE+0xA0000),%eax 433 movl _atdevphys,%edx /* get pte PA */ 434 subl _KPTphys,%edx /* remove base of ptes, now have phys offset */ 435 shll $PGSHIFT-2,%edx /* corresponding to virt offset */ 436 addl $KERNBASE,%edx /* add virtual base */ 437 movl %edx,_atdevbase 438 addl %eax,%edx 439 movl %edx,_Crtat 440 441 /* set up bootstrap stack - 48 bytes */ 442 movl $_kstack+UPAGES*NBPG-4*12,%esp /* bootstrap stack end location */ 443 xorl %eax,%eax /* mark end of frames */ 444 movl %eax,%ebp 445 movl _proc0paddr,%eax 446 movl %esi,PCB_CR3(%eax) 447 448#ifdef BDE_DEBUGGER 449 /* relocate debugger gdt entries */ 450 451 movl $_gdt+8*9,%eax /* adjust slots 9-17 */ 452 movl $9,%ecx 453reloc_gdt: 454 movb $0xfe,7(%eax) /* top byte of base addresses, was 0, */ 455 addl $8,%eax /* now KERNBASE>>24 */ 456 loop reloc_gdt 457 458 cmpl $0,_bdb_exists 459 je 1f 460 int $3 4611: 462#endif 463 464 /* 465 * Skip over the page tables and the kernel stack 466 */ 467 lea ((1+UPAGES+1+NKPT)*NBPG)(%esi),%esi 468 469 pushl %esi /* value of first for init386(first) */ 470 call _init386 /* wire 386 chip for unix operation */ 471 472 movl $0,_PTD 473 call _main /* autoconfiguration, mountroot etc */ 474 popl %esi 475 476 /* 477 * now we've run main() and determined what cpu-type we are, we can 478 * enable WP mode on i486 cpus and above. 479 * on return from main(), we are process 1 480 * set up address space and stack so that we can 'return' to user mode 481 */ 482 483 .globl __ucodesel,__udatasel 484 movl __ucodesel,%eax 485 movl __udatasel,%ecx 486 /* build outer stack frame */ 487 pushl %ecx /* user ss */ 488 pushl $USRSTACK /* user esp */ 489 pushl %eax /* user cs */ 490 pushl $0 /* user ip */ 491 movl %cx,%ds 492 movl %cx,%es 493 movl %ax,%fs /* double map cs to fs */ 494 movl %cx,%gs /* and ds to gs */ 495 lret /* goto user! */ 496 497 pushl $lretmsg1 /* "should never get here!" */ 498 call _panic 499lretmsg1: 500 .asciz "lret: toinit\n" 501 502 503#define LCALL(x,y) .byte 0x9a ; .long y; .word x 504/* 505 * Icode is copied out to process 1 and executed in user mode: 506 * execve("/sbin/init", argv, envp); exit(0); 507 * If the execve fails, process 1 exits and the system panics. 508 */ 509NON_GPROF_ENTRY(icode) 510 pushl $0 /* envp for execve() */ 511 512# pushl $argv-_icode /* can't do this 'cos gas 1.38 is broken */ 513 movl $argv,%eax 514 subl $_icode,%eax 515 pushl %eax /* argp for execve() */ 516 517# pushl $init-_icode 518 movl $init,%eax 519 subl $_icode,%eax 520 pushl %eax /* fname for execve() */ 521 522 pushl %eax /* dummy return address */ 523 524 movl $SYS_execve,%eax 525 LCALL(0x7,0x0) 526 527 /* exit if something botches up in the above execve() */ 528 pushl %eax /* execve failed, the errno will do for an */ 529 /* exit code because errnos are < 128 */ 530 pushl %eax /* dummy return address */ 531 movl $SYS_exit,%eax 532 LCALL(0x7,0x0) 533 534init: 535 .asciz "/sbin/init" 536 ALIGN_DATA 537argv: 538 .long init+6-_icode /* argv[0] = "init" ("/sbin/init" + 6) */ 539 .long eicode-_icode /* argv[1] follows icode after copyout */ 540 .long 0 541eicode: 542 543 .globl _szicode 544_szicode: 545 .long _szicode-_icode 546 547NON_GPROF_ENTRY(sigcode) 548 call SIGF_HANDLER(%esp) 549 lea SIGF_SC(%esp),%eax /* scp (the call may have clobbered the */ 550 /* copy at 8(%esp)) */ 551 pushl %eax 552 pushl %eax /* junk to fake return address */ 553 movl $103,%eax /* XXX sigreturn() */ 554 LCALL(0x7,0) /* enter kernel with args on stack */ 555 hlt /* never gets here */ 556 557 .globl _szsigcode 558_szsigcode: 559 .long _szsigcode-_sigcode 560 561