Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/locore.s
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
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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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)locore.s 7.3 (Berkeley) 5/13/91 33 * $FreeBSD$ 34 * 35 * originally from: locore.s, by William F. Jolitz 36 * 37 * Substantially rewritten by David Greenman, Rod Grimes, 38 * Bruce Evans, Wolfgang Solfrank, Poul-Henning Kamp 39 * and many others. 40 */ 41 42 #include "opt_bootp.h" 43 #include "opt_nfsroot.h" 44 #include "opt_pmap.h" 45 46 #include <sys/reboot.h> 47 48 #include <machine/asmacros.h> 49 #include <machine/cputypes.h> 50 #include <machine/psl.h> 51 #include <machine/pmap.h> 52 #include <machine/specialreg.h> 53 54 #include "assym.inc" 55 56 /* 57 * Compiled KERNBASE location and the kernel load address, now identical. 58 */ 59 .globl kernbase 60 .set kernbase,KERNBASE 61 .globl kernload 62 .set kernload,KERNLOAD 63 64 /* 65 * Globals 66 */ 67 .data 68 ALIGN_DATA /* just to be sure */ 69 70 .space 0x2000 /* space for tmpstk - temporary stack */ 71 tmpstk: 72 73 .globl bootinfo 74 bootinfo: .space BOOTINFO_SIZE /* bootinfo that we can handle */ 75 76 .text 77 /********************************************************************** 78 * 79 * This is where the bootblocks start us, set the ball rolling... 80 * 81 */ 82 NON_GPROF_ENTRY(btext) 83 84 /* Tell the bios to warmboot next time */ 85 movw $0x1234,0x472 86 87 /* Set up a real frame in case the double return in newboot is executed. */ 88 xorl %ebp,%ebp 89 pushl %ebp 90 movl %esp, %ebp 91 92 /* Don't trust what the BIOS gives for eflags. */ 93 pushl $PSL_KERNEL 94 popfl 95 96 /* 97 * Don't trust what the BIOS gives for %fs and %gs. Trust the bootstrap 98 * to set %cs, %ds, %es and %ss. 99 */ 100 mov %ds, %ax 101 mov %ax, %fs 102 mov %ax, %gs 103 104 /* 105 * Clear the bss. Not all boot programs do it, and it is our job anyway. 106 * 107 * XXX we don't check that there is memory for our bss and page tables 108 * before using it. 109 * 110 * Note: we must be careful to not overwrite an active gdt or idt. They 111 * inactive from now until we switch to new ones, since we don't load any 112 * more segment registers or permit interrupts until after the switch. 113 */ 114 movl $__bss_end,%ecx 115 movl $__bss_start,%edi 116 subl %edi,%ecx 117 xorl %eax,%eax 118 cld 119 rep 120 stosb 121 122 call recover_bootinfo 123 124 /* Get onto a stack that we can trust. */ 125 /* 126 * XXX this step is delayed in case recover_bootinfo needs to return via 127 * the old stack, but it need not be, since recover_bootinfo actually 128 * returns via the old frame. 129 */ 130 movl $tmpstk,%esp 131 132 call identify_cpu 133 call pmap_cold 134 135 /* set up bootstrap stack */ 136 movl proc0kstack,%eax /* location of in-kernel stack */ 137 138 /* 139 * Only use bottom page for init386(). init386() calculates the 140 * PCB + FPU save area size and returns the true top of stack. 141 */ 142 leal PAGE_SIZE(%eax),%esp 143 144 xorl %ebp,%ebp /* mark end of frames */ 145 146 pushl physfree /* value of first for init386(first) */ 147 call init386 /* wire 386 chip for unix operation */ 148 149 /* 150 * Clean up the stack in a way that db_numargs() understands, so 151 * that backtraces in ddb don't underrun the stack. Traps for 152 * inaccessible memory are more fatal than usual this early. 153 */ 154 addl $4,%esp 155 156 /* Switch to true top of stack. */ 157 movl %eax,%esp 158 159 call mi_startup /* autoconfiguration, mountroot etc */ 160 /* NOTREACHED */ 161 addl $0,%esp /* for db_numargs() again */ 162 163 /********************************************************************** 164 * 165 * Recover the bootinfo passed to us from the boot program 166 * 167 */ 168 recover_bootinfo: 169 /* 170 * This code is called in different ways depending on what loaded 171 * and started the kernel. This is used to detect how we get the 172 * arguments from the other code and what we do with them. 173 * 174 * Old disk boot blocks: 175 * (*btext)(howto, bootdev, cyloffset, esym); 176 * [return address == 0, and can NOT be returned to] 177 * [cyloffset was not supported by the FreeBSD boot code 178 * and always passed in as 0] 179 * [esym is also known as total in the boot code, and 180 * was never properly supported by the FreeBSD boot code] 181 * 182 * Old diskless netboot code: 183 * (*btext)(0,0,0,0,&nfsdiskless,0,0,0); 184 * [return address != 0, and can NOT be returned to] 185 * If we are being booted by this code it will NOT work, 186 * so we are just going to halt if we find this case. 187 * 188 * New uniform boot code: 189 * (*btext)(howto, bootdev, 0, 0, 0, &bootinfo) 190 * [return address != 0, and can be returned to] 191 * 192 * There may seem to be a lot of wasted arguments in here, but 193 * that is so the newer boot code can still load very old kernels 194 * and old boot code can load new kernels. 195 */ 196 197 /* 198 * The old style disk boot blocks fake a frame on the stack and 199 * did an lret to get here. The frame on the stack has a return 200 * address of 0. 201 */ 202 cmpl $0,4(%ebp) 203 je olddiskboot 204 205 /* 206 * We have some form of return address, so this is either the 207 * old diskless netboot code, or the new uniform code. That can 208 * be detected by looking at the 5th argument, if it is 0 209 * we are being booted by the new uniform boot code. 210 */ 211 cmpl $0,24(%ebp) 212 je newboot 213 214 /* 215 * Seems we have been loaded by the old diskless boot code, we 216 * don't stand a chance of running as the diskless structure 217 * changed considerably between the two, so just halt. 218 */ 219 hlt 220 221 /* 222 * We have been loaded by the new uniform boot code. 223 * Let's check the bootinfo version, and if we do not understand 224 * it we return to the loader with a status of 1 to indicate this error 225 */ 226 newboot: 227 movl 28(%ebp),%ebx /* &bootinfo.version */ 228 movl BI_VERSION(%ebx),%eax 229 cmpl $1,%eax /* We only understand version 1 */ 230 je 1f 231 movl $1,%eax /* Return status */ 232 leave 233 /* 234 * XXX this returns to our caller's caller (as is required) since 235 * we didn't set up a frame and our caller did. 236 */ 237 ret 238 239 1: 240 /* 241 * If we have a kernelname copy it in 242 */ 243 movl BI_KERNELNAME(%ebx),%esi 244 cmpl $0,%esi 245 je 2f /* No kernelname */ 246 movl $MAXPATHLEN,%ecx /* Brute force!!! */ 247 movl $kernelname,%edi 248 cmpb $'/',(%esi) /* Make sure it starts with a slash */ 249 je 1f 250 movb $'/',(%edi) 251 incl %edi 252 decl %ecx 253 1: 254 cld 255 rep 256 movsb 257 258 2: 259 /* 260 * Determine the size of the boot loader's copy of the bootinfo 261 * struct. This is impossible to do properly because old versions 262 * of the struct don't contain a size field and there are 2 old 263 * versions with the same version number. 264 */ 265 movl $BI_ENDCOMMON,%ecx /* prepare for sizeless version */ 266 testl $RB_BOOTINFO,8(%ebp) /* bi_size (and bootinfo) valid? */ 267 je got_bi_size /* no, sizeless version */ 268 movl BI_SIZE(%ebx),%ecx 269 got_bi_size: 270 271 /* 272 * Copy the common part of the bootinfo struct 273 */ 274 movl %ebx,%esi 275 movl $bootinfo,%edi 276 cmpl $BOOTINFO_SIZE,%ecx 277 jbe got_common_bi_size 278 movl $BOOTINFO_SIZE,%ecx 279 got_common_bi_size: 280 cld 281 rep 282 movsb 283 284 #ifdef NFS_ROOT 285 #ifndef BOOTP_NFSV3 286 /* 287 * If we have a nfs_diskless structure copy it in 288 */ 289 movl BI_NFS_DISKLESS(%ebx),%esi 290 cmpl $0,%esi 291 je olddiskboot 292 movl $nfs_diskless,%edi 293 movl $NFSDISKLESS_SIZE,%ecx 294 cld 295 rep 296 movsb 297 movl $nfs_diskless_valid,%edi 298 movl $1,(%edi) 299 #endif 300 #endif 301 302 /* 303 * The old style disk boot. 304 * (*btext)(howto, bootdev, cyloffset, esym); 305 * Note that the newer boot code just falls into here to pick 306 * up howto and bootdev, cyloffset and esym are no longer used 307 */ 308 olddiskboot: 309 movl 8(%ebp),%eax 310 movl %eax,boothowto 311 movl 12(%ebp),%eax 312 movl %eax,bootdev 313 314 ret 315 316 317 /********************************************************************** 318 * 319 * Identify the CPU and initialize anything special about it 320 * 321 */ 322 ENTRY(identify_cpu) 323 324 pushl %ebx 325 326 /* Try to toggle alignment check flag; does not exist on 386. */ 327 pushfl 328 popl %eax 329 movl %eax,%ecx 330 orl $PSL_AC,%eax 331 pushl %eax 332 popfl 333 pushfl 334 popl %eax 335 xorl %ecx,%eax 336 andl $PSL_AC,%eax 337 pushl %ecx 338 popfl 339 340 testl %eax,%eax 341 jnz try486 342 343 /* NexGen CPU does not have alignment check flag. */ 344 pushfl 345 movl $0x5555, %eax 346 xorl %edx, %edx 347 movl $2, %ecx 348 clc 349 divl %ecx 350 jz trynexgen 351 popfl 352 movl $CPU_386,cpu 353 jmp 3f 354 355 trynexgen: 356 popfl 357 movl $CPU_NX586,cpu 358 movl $0x4778654e,cpu_vendor # store vendor string 359 movl $0x72446e65,cpu_vendor+4 360 movl $0x6e657669,cpu_vendor+8 361 movl $0,cpu_vendor+12 362 jmp 3f 363 364 try486: /* Try to toggle identification flag; does not exist on early 486s. */ 365 pushfl 366 popl %eax 367 movl %eax,%ecx 368 xorl $PSL_ID,%eax 369 pushl %eax 370 popfl 371 pushfl 372 popl %eax 373 xorl %ecx,%eax 374 andl $PSL_ID,%eax 375 pushl %ecx 376 popfl 377 378 testl %eax,%eax 379 jnz trycpuid 380 movl $CPU_486,cpu 381 382 /* 383 * Check Cyrix CPU 384 * Cyrix CPUs do not change the undefined flags following 385 * execution of the divide instruction which divides 5 by 2. 386 * 387 * Note: CPUID is enabled on M2, so it passes another way. 388 */ 389 pushfl 390 movl $0x5555, %eax 391 xorl %edx, %edx 392 movl $2, %ecx 393 clc 394 divl %ecx 395 jnc trycyrix 396 popfl 397 jmp 3f /* You may use Intel CPU. */ 398 399 trycyrix: 400 popfl 401 /* 402 * IBM Bluelighting CPU also doesn't change the undefined flags. 403 * Because IBM doesn't disclose the information for Bluelighting 404 * CPU, we couldn't distinguish it from Cyrix's (including IBM 405 * brand of Cyrix CPUs). 406 */ 407 movl $0x69727943,cpu_vendor # store vendor string 408 movl $0x736e4978,cpu_vendor+4 409 movl $0x64616574,cpu_vendor+8 410 jmp 3f 411 412 trycpuid: /* Use the `cpuid' instruction. */ 413 xorl %eax,%eax 414 cpuid # cpuid 0 415 movl %eax,cpu_high # highest capability 416 movl %ebx,cpu_vendor # store vendor string 417 movl %edx,cpu_vendor+4 418 movl %ecx,cpu_vendor+8 419 movb $0,cpu_vendor+12 420 421 movl $1,%eax 422 cpuid # cpuid 1 423 movl %eax,cpu_id # store cpu_id 424 movl %ebx,cpu_procinfo # store cpu_procinfo 425 movl %edx,cpu_feature # store cpu_feature 426 movl %ecx,cpu_feature2 # store cpu_feature2 427 rorl $8,%eax # extract family type 428 andl $15,%eax 429 cmpl $5,%eax 430 jae 1f 431 432 /* less than Pentium; must be 486 */ 433 movl $CPU_486,cpu 434 jmp 3f 435 1: 436 /* a Pentium? */ 437 cmpl $5,%eax 438 jne 2f 439 movl $CPU_586,cpu 440 jmp 3f 441 2: 442 /* Greater than Pentium...call it a Pentium Pro */ 443 movl $CPU_686,cpu 444 3: 445 popl %ebx 446 ret 447 END(identify_cpu) 448 449 #ifdef XENHVM 450 /* Xen Hypercall page */ 451 .text 452 .p2align PAGE_SHIFT, 0x90 /* Hypercall_page needs to be PAGE aligned */ 453 454 NON_GPROF_ENTRY(hypercall_page) 455 .skip 0x1000, 0x90 /* Fill with "nop"s */ 456 #endif
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