locore.s revision 1058
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 1.14 1994/01/31 04:39:37 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 "errno.h" /* error return codes */ 53#include "machine/specialreg.h" /* x86 special registers */ 54#include "i386/isa/debug.h" /* BDE debugging macros */ 55#include "machine/cputypes.h" /* x86 cpu type definitions */ 56#include "syscall.h" /* system call numbers */ 57#include "machine/asmacros.h" /* miscellaneous asm macros */ 58 59/* 60 * XXX 61 * 62 * Note: This version greatly munged to avoid various assembler errors 63 * that may be fixed in newer versions of gas. Perhaps newer versions 64 * will have more pleasant appearance. 65 */ 66 67/* 68 * PTmap is recursive pagemap at top of virtual address space. 69 * Within PTmap, the page directory can be found (third indirection). 70 */ 71 .globl _PTmap,_PTD,_PTDpde,_Sysmap 72 .set _PTmap,PTDPTDI << PDRSHIFT 73 .set _PTD,_PTmap + (PTDPTDI * NBPG) 74 .set _PTDpde,_PTD + (PTDPTDI * PDESIZE) 75 76/* Sysmap is the base address of the kernel page tables */ 77 .set _Sysmap,_PTmap + (KPTDI * NBPG) 78 79/* 80 * APTmap, APTD is the alternate recursive pagemap. 81 * It's used when modifying another process's page tables. 82 */ 83 .globl _APTmap,_APTD,_APTDpde 84 .set _APTmap,APTDPTDI << PDRSHIFT 85 .set _APTD,_APTmap + (APTDPTDI * NBPG) 86 .set _APTDpde,_PTD + (APTDPTDI * PDESIZE) 87 88/* 89 * Access to each processes kernel stack is via a region of 90 * per-process address space (at the beginning), immediatly above 91 * the user process stack. 92 */ 93 .set _kstack,USRSTACK 94 .globl _kstack 95 96/* 97 * Globals 98 */ 99 .data 100 .globl _esym 101_esym: .long 0 /* ptr to end of syms */ 102 103 .globl _boothowto,_bootdev,_curpcb 104 105 .globl _cpu,_cold,_atdevbase 106_cpu: .long 0 /* are we 386, 386sx, or 486 */ 107_cold: .long 1 /* cold till we are not */ 108_atdevbase: .long 0 /* location of start of iomem in virtual */ 109_atdevphys: .long 0 /* location of device mapping ptes (phys) */ 110 111 .globl _KERNend 112_KERNend: .long 0 /* phys addr end of kernel (just after bss) */ 113 114 .globl _IdlePTD,_KPTphys 115_IdlePTD: .long 0 /* phys addr of kernel PTD */ 116_KPTphys: .long 0 /* phys addr of kernel page tables */ 117 118 .globl _cyloffset 119_cyloffset: .long 0 /* cylinder offset from boot blocks */ 120 121 .globl _proc0paddr 122_proc0paddr: .long 0 /* address of proc 0 address space */ 123 124#ifdef BDE_DEBUGGER 125 .globl _bdb_exists /* flag to indicate BDE debugger is available */ 126_bde_exists: .long 0 127#endif 128 129 .globl tmpstk 130 .space 0x1000 131tmpstk: 132 133 134/* 135 * System Initialization 136 */ 137 .text 138 139/* 140 * btext: beginning of text section. 141 * Also the entry point (jumped to directly from the boot blocks). 142 */ 143ENTRY(btext) 144 movw $0x1234,0x472 /* warm boot */ 145 jmp 1f 146 .space 0x500 /* skip over warm boot shit */ 147 148 /* 149 * pass parameters on stack (howto, bootdev, unit, cyloffset, esym) 150 * note: (%esp) is return address of boot 151 * ( if we want to hold onto /boot, it's physical %esp up to _end) 152 */ 153 154 1: movl 4(%esp),%eax 155 movl %eax,_boothowto-KERNBASE 156 movl 8(%esp),%eax 157 movl %eax,_bootdev-KERNBASE 158 movl 12(%esp),%eax 159 movl %eax,_cyloffset-KERNBASE 160 movl 16(%esp),%eax 161 addl $KERNBASE,%eax 162 movl %eax,_esym-KERNBASE 163#ifdef DISKLESS /* Copy diskless structure */ 164 movl _nfs_diskless_size-KERNBASE,%ecx 165 movl 20(%esp),%esi 166 movl $(_nfs_diskless-KERNBASE),%edi 167 rep 168 movsb 169#endif 170 171 /* find out our CPU type. */ 172 pushfl 173 popl %eax 174 movl %eax,%ecx 175 xorl $0x40000,%eax 176 pushl %eax 177 popfl 178 pushfl 179 popl %eax 180 xorl %ecx,%eax 181 shrl $18,%eax 182 andl $1,%eax 183 push %ecx 184 popfl 185 186 cmpl $0,%eax 187 jne 1f 188 movl $CPU_386,_cpu-KERNBASE 189 jmp 2f 1901: movl $CPU_486,_cpu-KERNBASE 1912: 192 193 /* 194 * Finished with old stack; load new %esp now instead of later so 195 * we can trace this code without having to worry about the trace 196 * trap clobbering the memory test or the zeroing of the bss+bootstrap 197 * page tables. 198 * 199 * XXX - wdboot clears the bss after testing that this is safe. 200 * This is too wasteful - memory below 640K is scarce. The boot 201 * program should check: 202 * text+data <= &stack_variable - more_space_for_stack 203 * text+data+bss+pad+space_for_page_tables <= end_of_memory 204 * Oops, the gdt is in the carcass of the boot program so clearing 205 * the rest of memory is still not possible. 206 */ 207 movl $tmpstk-KERNBASE,%esp /* bootstrap stack end location */ 208 209/* 210 * Virtual address space of kernel: 211 * 212 * text | data | bss | [syms] | page dir | proc0 kernel stack | usr stk map | Sysmap 213 * pages: 1 UPAGES (2) 1 NKPT (7) 214 */ 215 216/* find end of kernel image */ 217 movl $_end-KERNBASE,%ecx 218 addl $NBPG-1,%ecx /* page align up */ 219 andl $~(NBPG-1),%ecx 220 movl %ecx,%esi /* esi=start of tables */ 221 movl %ecx,_KERNend-KERNBASE /* save end of kernel */ 222 223/* clear bss */ 224 movl $_edata-KERNBASE,%edi 225 subl %edi,%ecx /* get amount to clear */ 226 xorl %eax,%eax /* specify zero fill */ 227 cld 228 rep 229 stosb 230 231/* 232 * The value in esi is both the end of the kernel bss and a pointer to 233 * the kernel page directory, and is used by the rest of locore to build 234 * the tables. 235 * esi + 1(page dir) + 2(UPAGES) + 1(p0stack) + NKPT(number of kernel 236 * page table pages) is then passed on the stack to init386(first) as 237 * the value first. esi should ALWAYS be page aligned!! 238 */ 239 movl %esi,%ecx /* Get current first availiable address */ 240 241/* clear pagetables, page directory, stack, etc... */ 242 movl %esi,%edi /* base (page directory) */ 243 movl $((1+UPAGES+1+NKPT)*NBPG),%ecx /* amount to clear */ 244 xorl %eax,%eax /* specify zero fill */ 245 cld 246 rep 247 stosb 248 249/* physical address of Idle proc/kernel page directory */ 250 movl %esi,_IdlePTD-KERNBASE 251 252/* 253 * fillkpt 254 * eax = (page frame address | control | status) == pte 255 * ebx = address of page table 256 * ecx = how many pages to map 257 */ 258#define fillkpt \ 2591: movl %eax,(%ebx) ; \ 260 addl $NBPG,%eax ; /* increment physical address */ \ 261 addl $4,%ebx ; /* next pte */ \ 262 loop 1b ; 263 264/* 265 * Map Kernel 266 * 267 * First step - build page tables 268 */ 269#if defined (KGDB) || defined (BDE_DEBUGGER) 270 movl _KERNend-KERNBASE,%ecx /* this much memory, */ 271 shrl $PGSHIFT,%ecx /* for this many PTEs */ 272#ifdef BDE_DEBUGGER 273 cmpl $0xa0,%ecx /* XXX - cover debugger pages */ 274 jae 1f 275 movl $0xa0,%ecx 2761: 277#endif /* BDE_DEBUGGER */ 278 movl $PG_V|PG_KW,%eax /* having these bits set, */ 279 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 280 movl %ebx,_KPTphys-KERNBASE /* save in global */ 281 fillkpt 282 283#else /* !KGDB && !BDE_DEBUGGER */ 284 /* write protect kernel text (doesn't do a thing for 386's - only 486's) */ 285 movl $_etext-KERNBASE,%ecx /* get size of text */ 286 shrl $PGSHIFT,%ecx /* for this many PTEs */ 287 movl $PG_V|PG_KR,%eax /* specify read only */ 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 /* data and bss are r/w */ 293 andl $PG_FRAME,%eax /* strip to just addr of bss */ 294 movl _KERNend-KERNBASE,%ecx /* calculate size */ 295 subl %eax,%ecx 296 shrl $PGSHIFT,%ecx 297 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 298 fillkpt 299#endif 300 301/* now initialize the page dir, upages, p0stack PT, and page tables */ 302 303 movl $(1+UPAGES+1+NKPT),%ecx /* number of PTEs */ 304 movl %esi,%eax /* phys address of PTD */ 305 andl $PG_FRAME,%eax /* convert to PFN, should be a NOP */ 306 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 307 movl %esi,%ebx /* calculate pte offset to ptd */ 308 shrl $PGSHIFT-2,%ebx 309 addl %esi,%ebx /* address of page directory */ 310 addl $((1+UPAGES+1)*NBPG),%ebx /* offset to kernel page tables */ 311 fillkpt 312 313/* map I/O memory map */ 314 315 movl _KPTphys-KERNBASE,%ebx /* base of kernel page tables */ 316 lea (0xa0 * PTESIZE)(%ebx),%ebx /* hardwire ISA hole at KERNBASE + 0xa0000 */ 317 movl $0x100-0xa0,%ecx /* for this many pte s, */ 318 movl $(0xa0000|PG_V|PG_KW|PG_N),%eax /* valid, kernel read/write, non-cacheable */ 319 movl %ebx,_atdevphys-KERNBASE /* save phys addr of ptes */ 320 fillkpt 321 322 /* map proc 0's kernel stack into user page table page */ 323 324 movl $UPAGES,%ecx /* for this many pte s, */ 325 lea (1*NBPG)(%esi),%eax /* physical address in proc 0 */ 326 lea (KERNBASE)(%eax),%edx /* change into virtual addr */ 327 movl %edx,_proc0paddr-KERNBASE /* save VA for proc 0 init */ 328 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 329 lea ((1+UPAGES)*NBPG)(%esi),%ebx /* addr of stack page table in proc 0 */ 330 addl $(KSTKPTEOFF * PTESIZE),%ebx /* offset to kernel stack PTE */ 331 fillkpt 332 333/* 334 * Initialize kernel page table directory 335 */ 336 /* install a pde for temporary double map of bottom of VA */ 337 movl _KPTphys-KERNBASE,%eax 338 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 339 movl %eax,(%esi) /* which is where temp maps! */ 340 341 /* initialize kernel pde's */ 342 movl $(NKPT),%ecx /* for this many PDEs */ 343 lea (KPTDI*PDESIZE)(%esi),%ebx /* offset of pde for kernel */ 344 fillkpt 345 346 /* install a pde recursively mapping page directory as a page table! */ 347 movl %esi,%eax /* phys address of ptd in proc 0 */ 348 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 349 movl %eax,PTDPTDI*PDESIZE(%esi) /* which is where PTmap maps! */ 350 351 /* install a pde to map kernel stack for proc 0 */ 352 lea ((1+UPAGES)*NBPG)(%esi),%eax /* physical address of pt in proc 0 */ 353 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 354 movl %eax,KSTKPTDI*PDESIZE(%esi) /* which is where kernel stack maps! */ 355 356#ifdef BDE_DEBUGGER 357 /* copy and convert stuff from old gdt and idt for debugger */ 358 359 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */ 360 jne 1f 361 movb $1,_bdb_exists-KERNBASE 3621: 363 pushal 364 subl $2*6,%esp 365 366 sgdt (%esp) 367 movl 2(%esp),%esi /* base address of current gdt */ 368 movl $_gdt-KERNBASE,%edi 369 movl %edi,2(%esp) 370 movl $8*18/4,%ecx 371 rep /* copy gdt */ 372 movsl 373 movl $_gdt-KERNBASE,-8+2(%edi) /* adjust gdt self-ptr */ 374 movb $0x92,-8+5(%edi) 375 376 sidt 6(%esp) 377 movl 6+2(%esp),%esi /* base address of current idt */ 378 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */ 379 movw 8(%esi),%ax 380 movl %eax,bdb_dbg_ljmp+1-KERNBASE /* ... immediate offset ... */ 381 movl 8+2(%esi),%eax 382 movw %ax,bdb_dbg_ljmp+5-KERNBASE /* ... and selector for ljmp */ 383 movl 24+4(%esi),%eax /* same for bpt descriptor */ 384 movw 24(%esi),%ax 385 movl %eax,bdb_bpt_ljmp+1-KERNBASE 386 movl 24+2(%esi),%eax 387 movw %ax,bdb_bpt_ljmp+5-KERNBASE 388 389 movl $_idt-KERNBASE,%edi 390 movl %edi,6+2(%esp) 391 movl $8*4/4,%ecx 392 rep /* copy idt */ 393 movsl 394 395 lgdt (%esp) 396 lidt 6(%esp) 397 398 addl $2*6,%esp 399 popal 400#endif 401 402 /* load base of page directory and enable mapping */ 403 movl %esi,%eax /* phys address of ptd in proc 0 */ 404 orl $I386_CR3PAT,%eax 405 movl %eax,%cr3 /* load ptd addr into mmu */ 406 movl %cr0,%eax /* get control word */ 407 orl $CR0_PE|CR0_PG,%eax /* enable paging */ 408 movl %eax,%cr0 /* and let's page NOW! */ 409 410 pushl $begin /* jump to high mem */ 411 ret 412 413begin: /* now running relocated at KERNBASE where the system is linked to run */ 414 415 .globl _Crtat /* XXX - locore should not know about */ 416 movl _Crtat,%eax /* variables of device drivers (pccons)! */ 417 subl $(KERNBASE+0xA0000),%eax 418 movl _atdevphys,%edx /* get pte PA */ 419 subl _KPTphys,%edx /* remove base of ptes, now have phys offset */ 420 shll $PGSHIFT-2,%edx /* corresponding to virt offset */ 421 addl $KERNBASE,%edx /* add virtual base */ 422 movl %edx,_atdevbase 423 addl %eax,%edx 424 movl %edx,_Crtat 425 426 /* set up bootstrap stack - 48 bytes */ 427 movl $_kstack+UPAGES*NBPG-4*12,%esp /* bootstrap stack end location */ 428 xorl %eax,%eax /* mark end of frames */ 429 movl %eax,%ebp 430 movl _proc0paddr,%eax 431 movl %esi,PCB_CR3(%eax) 432 433#ifdef BDE_DEBUGGER 434 /* relocate debugger gdt entries */ 435 436 movl $_gdt+8*9,%eax /* adjust slots 9-17 */ 437 movl $9,%ecx 438reloc_gdt: 439 movb $0xfe,7(%eax) /* top byte of base addresses, was 0, */ 440 addl $8,%eax /* now KERNBASE>>24 */ 441 loop reloc_gdt 442 443 cmpl $0,_bdb_exists 444 je 1f 445 int $3 4461: 447#endif 448 449 /* 450 * Skip over the page tables and the kernel stack 451 */ 452 lea ((1+UPAGES+1+NKPT)*NBPG)(%esi),%esi 453 454 pushl %esi /* value of first for init386(first) */ 455 call _init386 /* wire 386 chip for unix operation */ 456 457 movl $0,_PTD 458 call _main /* autoconfiguration, mountroot etc */ 459 popl %esi 460 461 /* 462 * now we've run main() and determined what cpu-type we are, we can 463 * enable WP mode on i486 cpus and above. 464 */ 465#if defined(I486_CPU) || defined(I586_CPU) 466 cmpl $CPUCLASS_386,_cpu_class 467 je 1f 468 movl %cr0,%eax /* get control word */ 469 orl $CR0_WP,%eax /* enable write protect for all modes */ 470 movl %eax,%cr0 /* and do it */ 471#endif 472 /* 473 * on return from main(), we are process 1 474 * set up address space and stack so that we can 'return' to user mode 475 */ 4761: 477 .globl __ucodesel,__udatasel 478 movl __ucodesel,%eax 479 movl __udatasel,%ecx 480 /* build outer stack frame */ 481 pushl %ecx /* user ss */ 482 pushl $USRSTACK /* user esp */ 483 pushl %eax /* user cs */ 484 pushl $0 /* user ip */ 485 movl %cx,%ds 486 movl %cx,%es 487 movl %ax,%fs /* double map cs to fs */ 488 movl %cx,%gs /* and ds to gs */ 489 lret /* goto user! */ 490 491 pushl $lretmsg1 /* "should never get here!" */ 492 call _panic 493lretmsg1: 494 .asciz "lret: toinit\n" 495 496 497#define LCALL(x,y) .byte 0x9a ; .long y; .word x 498/* 499 * Icode is copied out to process 1 and executed in user mode: 500 * execve("/sbin/init", argv, envp); exit(0); 501 * If the execve fails, process 1 exits and the system panics. 502 */ 503NON_GPROF_ENTRY(icode) 504 pushl $0 /* envp for execve() */ 505 506# pushl $argv-_icode /* can't do this 'cos gas 1.38 is broken */ 507 movl $argv,%eax 508 subl $_icode,%eax 509 pushl %eax /* argp for execve() */ 510 511# pushl $init-_icode 512 movl $init,%eax 513 subl $_icode,%eax 514 pushl %eax /* fname for execve() */ 515 516 pushl %eax /* dummy return address */ 517 518 movl $SYS_execve,%eax 519 LCALL(0x7,0x0) 520 521 /* exit if something botches up in the above execve() */ 522 pushl %eax /* execve failed, the errno will do for an */ 523 /* exit code because errnos are < 128 */ 524 pushl %eax /* dummy return address */ 525 movl $SYS_exit,%eax 526 LCALL(0x7,0x0) 527 528init: 529 .asciz "/sbin/init" 530 ALIGN_DATA 531argv: 532 .long init+6-_icode /* argv[0] = "init" ("/sbin/init" + 6) */ 533 .long eicode-_icode /* argv[1] follows icode after copyout */ 534 .long 0 535eicode: 536 537 .globl _szicode 538_szicode: 539 .long _szicode-_icode 540 541NON_GPROF_ENTRY(sigcode) 542 call SIGF_HANDLER(%esp) 543 lea SIGF_SC(%esp),%eax /* scp (the call may have clobbered the */ 544 /* copy at 8(%esp)) */ 545 pushl %eax 546 pushl %eax /* junk to fake return address */ 547 movl $103,%eax /* XXX sigreturn() */ 548 LCALL(0x7,0) /* enter kernel with args on stack */ 549 hlt /* never gets here */ 550 551 .globl _szsigcode 552_szsigcode: 553 .long _szsigcode-_sigcode 554 555