locore.s revision 1998
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 1.18 1994/06/06 14:12:48 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 "machine/cputypes.h" /* x86 cpu type definitions */ 55#include "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 17 /* 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 /* 150 * pass parameters on stack (howto, bootdev, unit, cyloffset, esym) 151 * note: (%esp) is return address of boot 152 * ( if we want to hold onto /boot, it's physical %esp up to _end) 153 */ 154 155 1: movl 4(%esp),%eax 156 movl %eax,_boothowto-KERNBASE 157 movl 8(%esp),%eax 158 movl %eax,_bootdev-KERNBASE 159 movl 12(%esp),%eax 160 movl %eax,_cyloffset-KERNBASE 161 movl 16(%esp),%eax 162 addl $KERNBASE,%eax 163 movl %eax,_esym-KERNBASE 164#ifdef DISKLESS /* Copy diskless structure */ 165 movl _nfs_diskless_size-KERNBASE,%ecx 166 movl 20(%esp),%esi 167 movl $(_nfs_diskless-KERNBASE),%edi 168 cld 169 rep 170 movsb 171#endif 172 173 /* Find out our CPU type. */ 174 175 /* Try to toggle alignment check flag; does not exist on 386. */ 176 pushfl 177 popl %eax 178 movl %eax,%ecx 179 orl $PSL_AC,%eax 180 pushl %eax 181 popfl 182 pushfl 183 popl %eax 184 xorl %ecx,%eax 185 andl $PSL_AC,%eax 186 pushl %ecx 187 popfl 188 189 testl %eax,%eax 190 jnz 1f 191 movl $CPU_386,_cpu-KERNBASE 192 jmp 2f 193 1941: /* Try to toggle identification flag; does not exist on early 486s. */ 195 pushfl 196 popl %eax 197 movl %eax,%ecx 198 xorl $PSL_ID,%eax 199 pushl %eax 200 popfl 201 pushfl 202 popl %eax 203 xorl %ecx,%eax 204 andl $PSL_ID,%eax 205 pushl %ecx 206 popfl 207 208 testl %eax,%eax 209 jnz 1f 210 movl $CPU_486,_cpu-KERNBASE 211 jmp 2f 212 2131: /* Use the `cpuid' instruction. */ 214 xorl %eax,%eax 215 .byte 0x0f,0xa2 # cpuid 0 216 movl %ebx,_cpu_vendor-KERNBASE # store vendor string 217 movl %edx,_cpu_vendor+4-KERNBASE 218 movl %ecx,_cpu_vendor+8-KERNBASE 219 movb $0,_cpu_vendor+12-KERNBASE 220 221 movl $1,%eax 222 .byte 0x0f,0xa2 # cpuid 1 223 movl %eax,_cpu_id-KERNBASE # store cpu_id 224 rorl $8,%eax # extract family type 225 andl $15,%eax 226 cmpl $5,%eax 227 jae 1f 228 229 /* less than Pentium; must be 486 */ 230 movl $CPU_486,_cpu-KERNBASE 231 jmp 2f 232 2331: movl $CPU_586,_cpu-KERNBASE 2342: 235 236 /* 237 * Finished with old stack; load new %esp now instead of later so 238 * we can trace this code without having to worry about the trace 239 * trap clobbering the memory test or the zeroing of the bss+bootstrap 240 * page tables. 241 * 242 * XXX - wdboot clears the bss after testing that this is safe. 243 * This is too wasteful - memory below 640K is scarce. The boot 244 * program should check: 245 * text+data <= &stack_variable - more_space_for_stack 246 * text+data+bss+pad+space_for_page_tables <= end_of_memory 247 * Oops, the gdt is in the carcass of the boot program so clearing 248 * the rest of memory is still not possible. 249 */ 250 movl $tmpstk-KERNBASE,%esp /* bootstrap stack end location */ 251 252/* 253 * Virtual address space of kernel: 254 * 255 * text | data | bss | [syms] | page dir | proc0 kernel stack | usr stk map | Sysmap 256 * pages: 1 UPAGES (2) 1 NKPT (7) 257 */ 258 259/* find end of kernel image */ 260 movl $_end-KERNBASE,%ecx 261 addl $NBPG-1,%ecx /* page align up */ 262 andl $~(NBPG-1),%ecx 263 movl %ecx,%esi /* esi = start of free memory */ 264 movl %ecx,_KERNend-KERNBASE /* save end of kernel */ 265 266/* clear bss */ 267 movl $_edata-KERNBASE,%edi 268 subl %edi,%ecx /* get amount to clear */ 269 xorl %eax,%eax /* specify zero fill */ 270 cld 271 rep 272 stosb 273 274/* 275 * The value in esi is both the end of the kernel bss and a pointer to 276 * the kernel page directory, and is used by the rest of locore to build 277 * the tables. 278 * esi + 1(page dir) + 2(UPAGES) + 1(p0stack) + NKPT(number of kernel 279 * page table pages) is then passed on the stack to init386(first) as 280 * the value first. esi should ALWAYS be page aligned!! 281 */ 282 movl %esi,%ecx /* Get current first availiable address */ 283 284/* clear pagetables, page directory, stack, etc... */ 285 movl %esi,%edi /* base (page directory) */ 286 movl $((1+UPAGES+1+NKPT)*NBPG),%ecx /* amount to clear */ 287 xorl %eax,%eax /* specify zero fill */ 288 cld 289 rep 290 stosb 291 292/* physical address of Idle proc/kernel page directory */ 293 movl %esi,_IdlePTD-KERNBASE 294 295/* 296 * fillkpt 297 * eax = (page frame address | control | status) == pte 298 * ebx = address of page table 299 * ecx = how many pages to map 300 */ 301#define fillkpt \ 3021: movl %eax,(%ebx) ; \ 303 addl $NBPG,%eax ; /* increment physical address */ \ 304 addl $4,%ebx ; /* next pte */ \ 305 loop 1b ; 306 307/* 308 * Map Kernel 309 * 310 * First step - build page tables 311 */ 312#if defined (KGDB) || defined (BDE_DEBUGGER) 313 movl _KERNend-KERNBASE,%ecx /* this much memory, */ 314 shrl $PGSHIFT,%ecx /* for this many PTEs */ 315#ifdef BDE_DEBUGGER 316 cmpl $0xa0,%ecx /* XXX - cover debugger pages */ 317 jae 1f 318 movl $0xa0,%ecx 3191: 320#endif /* BDE_DEBUGGER */ 321 movl $PG_V|PG_KW|PG_NC_PWT,%eax /* kernel R/W, valid, cache write-through */ 322 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 323 movl %ebx,_KPTphys-KERNBASE /* save in global */ 324 fillkpt 325 326#else /* !KGDB && !BDE_DEBUGGER */ 327 /* write protect kernel text (doesn't do a thing for 386's - only 486's) */ 328 movl $_etext-KERNBASE,%ecx /* get size of text */ 329 shrl $PGSHIFT,%ecx /* for this many PTEs */ 330 movl $PG_V|PG_KR,%eax /* specify read only */ 331 lea ((1+UPAGES+1)*NBPG)(%esi),%ebx /* phys addr of kernel PT base */ 332 movl %ebx,_KPTphys-KERNBASE /* save in global */ 333 fillkpt 334 335 /* data and bss are r/w */ 336 andl $PG_FRAME,%eax /* strip to just addr of bss */ 337 movl _KERNend-KERNBASE,%ecx /* calculate size */ 338 subl %eax,%ecx 339 shrl $PGSHIFT,%ecx 340 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 341 fillkpt 342#endif /* KGDB || BDE_DEBUGGER */ 343 344/* now initialize the page dir, upages, p0stack PT, and page tables */ 345 346 movl $(1+UPAGES+1+NKPT),%ecx /* number of PTEs */ 347 movl %esi,%eax /* phys address of PTD */ 348 andl $PG_FRAME,%eax /* convert to PFN, should be a NOP */ 349 orl $PG_V|PG_KW|PG_NC_PWT,%eax /* valid, kernel read/write, cache write-though */ 350 movl %esi,%ebx /* calculate pte offset to ptd */ 351 shrl $PGSHIFT-2,%ebx 352 addl %esi,%ebx /* address of page directory */ 353 addl $((1+UPAGES+1)*NBPG),%ebx /* offset to kernel page tables */ 354 fillkpt 355 356/* map I/O memory map */ 357 358 movl _KPTphys-KERNBASE,%ebx /* base of kernel page tables */ 359 lea (0xa0 * PTESIZE)(%ebx),%ebx /* hardwire ISA hole at KERNBASE + 0xa0000 */ 360 movl $0x100-0xa0,%ecx /* for this many pte s, */ 361 movl $(0xa0000|PG_V|PG_KW|PG_N),%eax /* valid, kernel read/write, non-cacheable */ 362 movl %ebx,_atdevphys-KERNBASE /* save phys addr of ptes */ 363 fillkpt 364 365 /* map proc 0's kernel stack into user page table page */ 366 367 movl $UPAGES,%ecx /* for this many pte s, */ 368 lea (1*NBPG)(%esi),%eax /* physical address in proc 0 */ 369 lea (KERNBASE)(%eax),%edx /* change into virtual addr */ 370 movl %edx,_proc0paddr-KERNBASE /* save VA for proc 0 init */ 371 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 372 lea ((1+UPAGES)*NBPG)(%esi),%ebx /* addr of stack page table in proc 0 */ 373 addl $(KSTKPTEOFF * PTESIZE),%ebx /* offset to kernel stack PTE */ 374 fillkpt 375 376/* 377 * Initialize kernel page table directory 378 */ 379 /* install a pde for temporary double map of bottom of VA */ 380 movl _KPTphys-KERNBASE,%eax 381 orl $PG_V|PG_KW,%eax /* valid, kernel read/write */ 382 movl %eax,(%esi) /* which is where temp maps! */ 383 384 /* initialize kernel pde's */ 385 movl $(NKPT),%ecx /* for this many PDEs */ 386 lea (KPTDI*PDESIZE)(%esi),%ebx /* offset of pde for kernel */ 387 fillkpt 388 389 /* install a pde recursively mapping page directory as a page table! */ 390 movl %esi,%eax /* phys address of ptd in proc 0 */ 391 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 392 movl %eax,PTDPTDI*PDESIZE(%esi) /* which is where PTmap maps! */ 393 394 /* install a pde to map kernel stack for proc 0 */ 395 lea ((1+UPAGES)*NBPG)(%esi),%eax /* physical address of pt in proc 0 */ 396 orl $PG_V|PG_KW,%eax /* pde entry is valid */ 397 movl %eax,KSTKPTDI*PDESIZE(%esi) /* which is where kernel stack maps! */ 398 399#ifdef BDE_DEBUGGER 400 /* copy and convert stuff from old gdt and idt for debugger */ 401 402 cmpl $0x0375c339,0x96104 /* XXX - debugger signature */ 403 jne 1f 404 movb $1,_bdb_exists-KERNBASE 4051: 406 pushal 407 subl $2*6,%esp 408 409 sgdt (%esp) 410 movl 2(%esp),%esi /* base address of current gdt */ 411 movl $_gdt-KERNBASE,%edi 412 movl %edi,2(%esp) 413 movl $8*18/4,%ecx 414 cld 415 rep /* copy gdt */ 416 movsl 417 movl $_gdt-KERNBASE,-8+2(%edi) /* adjust gdt self-ptr */ 418 movb $0x92,-8+5(%edi) 419 420 sidt 6(%esp) 421 movl 6+2(%esp),%esi /* base address of current idt */ 422 movl 8+4(%esi),%eax /* convert dbg descriptor to ... */ 423 movw 8(%esi),%ax 424 movl %eax,bdb_dbg_ljmp+1-KERNBASE /* ... immediate offset ... */ 425 movl 8+2(%esi),%eax 426 movw %ax,bdb_dbg_ljmp+5-KERNBASE /* ... and selector for ljmp */ 427 movl 24+4(%esi),%eax /* same for bpt descriptor */ 428 movw 24(%esi),%ax 429 movl %eax,bdb_bpt_ljmp+1-KERNBASE 430 movl 24+2(%esi),%eax 431 movw %ax,bdb_bpt_ljmp+5-KERNBASE 432 433 movl $_idt-KERNBASE,%edi 434 movl %edi,6+2(%esp) 435 movl $8*4/4,%ecx 436 cld 437 rep /* copy idt */ 438 movsl 439 440 lgdt (%esp) 441 lidt 6(%esp) 442 443 addl $2*6,%esp 444 popal 445#endif /* BDE_DEBUGGER */ 446 447 /* load base of page directory and enable mapping */ 448 movl %esi,%eax /* phys address of ptd in proc 0 */ 449 orl $I386_CR3PAT,%eax 450 movl %eax,%cr3 /* load ptd addr into mmu */ 451 movl %cr0,%eax /* get control word */ 452 orl $CR0_PE|CR0_PG,%eax /* enable paging */ 453 movl %eax,%cr0 /* and let's page NOW! */ 454 455 pushl $begin /* jump to high mem */ 456 ret 457 458begin: /* now running relocated at KERNBASE where the system is linked to run */ 459 460 .globl _Crtat /* XXX - locore should not know about */ 461 movl _Crtat,%eax /* variables of device drivers (pccons)! */ 462 subl $(KERNBASE+0xA0000),%eax 463 movl _atdevphys,%edx /* get pte PA */ 464 subl _KPTphys,%edx /* remove base of ptes, now have phys offset */ 465 shll $PGSHIFT-2,%edx /* corresponding to virt offset */ 466 addl $KERNBASE,%edx /* add virtual base */ 467 movl %edx,_atdevbase 468 addl %eax,%edx 469 movl %edx,_Crtat 470 471 /* set up bootstrap stack - 48 bytes */ 472 movl $_kstack+UPAGES*NBPG-4*12,%esp /* bootstrap stack end location */ 473 xorl %eax,%eax /* mark end of frames */ 474 movl %eax,%ebp 475 movl _proc0paddr,%eax 476 movl %esi,PCB_CR3(%eax) 477 478#ifdef BDE_DEBUGGER 479 /* relocate debugger gdt entries */ 480 481 movl $_gdt+8*9,%eax /* adjust slots 9-17 */ 482 movl $9,%ecx 483reloc_gdt: 484 movb $KERNBASE>>24,7(%eax) /* top byte of base addresses, was 0, */ 485 addl $8,%eax /* now KERNBASE>>24 */ 486 loop reloc_gdt 487 488 cmpl $0,_bdb_exists 489 je 1f 490 int $3 4911: 492#endif /* BDE_DEBUGGER */ 493 494 /* 495 * Skip over the page tables and the kernel stack 496 */ 497 lea ((1+UPAGES+1+NKPT)*NBPG)(%esi),%esi 498 499 pushl %esi /* value of first for init386(first) */ 500 call _init386 /* wire 386 chip for unix operation */ 501 popl %esi 502 503#if 0 504 movl $0,_PTD 505#endif 506 507 .globl __ucodesel,__udatasel 508 509 pushl $0 /* unused */ 510 pushl __udatasel /* ss */ 511 pushl $0 /* esp - filled in by execve() */ 512 pushl $0x3200 /* eflags (ring 3, int enab) */ 513 pushl __ucodesel /* cs */ 514 pushl $0 /* eip - filled in by execve() */ 515 subl $(12*4),%esp /* space for rest of registers */ 516 517 pushl %esp /* call main with frame pointer */ 518 call _main /* autoconfiguration, mountroot etc */ 519 520 addl $(13*4),%esp /* back to a frame we can return with */ 521 522 /* 523 * now we've run main() and determined what cpu-type we are, we can 524 * enable WP mode on i486 cpus and above. 525 */ 526#if defined(I486_CPU) || defined(I586_CPU) 527 cmpl $CPUCLASS_386,_cpu_class 528 je 1f 529 movl %cr0,%eax /* get control word */ 530 orl $CR0_WP,%eax /* enable write protect for all modes */ 531 movl %eax,%cr0 /* and do it */ 532#endif 533 /* 534 * on return from main(), we are process 1 535 * set up address space and stack so that we can 'return' to user mode 536 */ 5371: 538 movl __ucodesel,%eax 539 movl __udatasel,%ecx 540 541 movl %cx,%ds 542 movl %cx,%es 543 movl %ax,%fs /* double map cs to fs */ 544 movl %cx,%gs /* and ds to gs */ 545 iret /* goto user! */ 546 547#define LCALL(x,y) .byte 0x9a ; .long y ; .word x 548 549NON_GPROF_ENTRY(sigcode) 550 call SIGF_HANDLER(%esp) 551 lea SIGF_SC(%esp),%eax /* scp (the call may have clobbered the */ 552 /* copy at 8(%esp)) */ 553 pushl %eax 554 pushl %eax /* junk to fake return address */ 555 movl $103,%eax /* XXX sigreturn() */ 556 LCALL(0x7,0) /* enter kernel with args on stack */ 557 hlt /* never gets here */ 558 559 .globl _szsigcode 560_szsigcode: 561 .long _szsigcode-_sigcode 562