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/exception.s
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1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD$ 34 */ 35 36 #include "npx.h" 37 38 #include <machine/asmacros.h> 39 #include <machine/ipl.h> 40 #include <machine/lock.h> 41 #include <machine/psl.h> 42 #include <machine/trap.h> 43 #ifdef SMP 44 #include <machine/smptests.h> /** various SMP options */ 45 #endif 46 47 #include "assym.s" 48 49 #ifdef SMP 50 #define MOVL_KPSEL_EAX movl $KPSEL,%eax 51 #else 52 #define MOVL_KPSEL_EAX 53 #endif 54 #define SEL_RPL_MASK 0x0003 55 56 .text 57 58 /*****************************************************************************/ 59 /* Trap handling */ 60 /*****************************************************************************/ 61 /* 62 * Trap and fault vector routines. 63 * 64 * Most traps are 'trap gates', SDT_SYS386TGT. A trap gate pushes state on 65 * the stack that mostly looks like an interrupt, but does not disable 66 * interrupts. A few of the traps we are use are interrupt gates, 67 * SDT_SYS386IGT, which are nearly the same thing except interrupts are 68 * disabled on entry. 69 * 70 * The cpu will push a certain amount of state onto the kernel stack for 71 * the current process. The amount of state depends on the type of trap 72 * and whether the trap crossed rings or not. See i386/include/frame.h. 73 * At the very least the current EFLAGS (status register, which includes 74 * the interrupt disable state prior to the trap), the code segment register, 75 * and the return instruction pointer are pushed by the cpu. The cpu 76 * will also push an 'error' code for certain traps. We push a dummy 77 * error code for those traps where the cpu doesn't in order to maintain 78 * a consistent frame. We also push a contrived 'trap number'. 79 * 80 * The cpu does not push the general registers, we must do that, and we 81 * must restore them prior to calling 'iret'. The cpu adjusts the %cs and 82 * %ss segment registers, but does not mess with %ds, %es, or %fs. Thus we 83 * must load them with appropriate values for supervisor mode operation. 84 * 85 * On entry to a trap or interrupt WE DO NOT OWN THE MP LOCK. This means 86 * that we must be careful in regards to accessing global variables. We 87 * save (push) the current cpl (our software interrupt disable mask), call 88 * the trap function, then call _doreti to restore the cpl and deal with 89 * ASTs (software interrupts). _doreti will determine if the restoration 90 * of the cpl unmasked any pending interrupts and will issue those interrupts 91 * synchronously prior to doing the iret. 92 * 93 * At the moment we must own the MP lock to do any cpl manipulation, which 94 * means we must own it prior to calling _doreti. The syscall case attempts 95 * to avoid this by handling a reduced set of cases itself and iret'ing. 96 */ 97 #define IDTVEC(name) ALIGN_TEXT; .globl __CONCAT(_X,name); \ 98 .type __CONCAT(_X,name),@function; __CONCAT(_X,name): 99 #define TRAP(a) pushl $(a) ; jmp _alltraps 100 101 #ifdef BDE_DEBUGGER 102 #define BDBTRAP(name) \ 103 ss ; \ 104 cmpb $0,_bdb_exists ; \ 105 je 1f ; \ 106 testb $SEL_RPL_MASK,4(%esp) ; \ 107 jne 1f ; \ 108 ss ; \ 109 .globl __CONCAT(__CONCAT(bdb_,name),_ljmp); \ 110 __CONCAT(__CONCAT(bdb_,name),_ljmp): \ 111 ljmp $0,$0 ; \ 112 1: 113 #else 114 #define BDBTRAP(name) 115 #endif 116 117 #define BPTTRAP(a) testl $PSL_I,4+8(%esp) ; je 1f ; sti ; 1: ; TRAP(a) 118 119 MCOUNT_LABEL(user) 120 MCOUNT_LABEL(btrap) 121 122 IDTVEC(div) 123 pushl $0; TRAP(T_DIVIDE) 124 IDTVEC(dbg) 125 BDBTRAP(dbg) 126 pushl $0; BPTTRAP(T_TRCTRAP) 127 IDTVEC(nmi) 128 pushl $0; TRAP(T_NMI) 129 IDTVEC(bpt) 130 BDBTRAP(bpt) 131 pushl $0; BPTTRAP(T_BPTFLT) 132 IDTVEC(ofl) 133 pushl $0; TRAP(T_OFLOW) 134 IDTVEC(bnd) 135 pushl $0; TRAP(T_BOUND) 136 IDTVEC(ill) 137 pushl $0; TRAP(T_PRIVINFLT) 138 IDTVEC(dna) 139 pushl $0; TRAP(T_DNA) 140 IDTVEC(fpusegm) 141 pushl $0; TRAP(T_FPOPFLT) 142 IDTVEC(tss) 143 TRAP(T_TSSFLT) 144 IDTVEC(missing) 145 TRAP(T_SEGNPFLT) 146 IDTVEC(stk) 147 TRAP(T_STKFLT) 148 IDTVEC(prot) 149 TRAP(T_PROTFLT) 150 IDTVEC(page) 151 TRAP(T_PAGEFLT) 152 IDTVEC(mchk) 153 pushl $0; TRAP(T_MCHK) 154 IDTVEC(rsvd) 155 pushl $0; TRAP(T_RESERVED) 156 157 IDTVEC(fpu) 158 #if NNPX > 0 159 /* 160 * Handle like an interrupt (except for accounting) so that we can 161 * call npx_intr to clear the error. It would be better to handle 162 * npx interrupts as traps. Nested interrupts would probably have 163 * to be converted to ASTs. 164 */ 165 pushl $0 /* dummy error code */ 166 pushl $0 /* dummy trap type */ 167 pushal 168 pushl %ds 169 pushl %es /* now stack frame is a trap frame */ 170 pushl %fs 171 mov $KDSEL,%ax 172 mov %ax,%ds 173 mov %ax,%es 174 MOVL_KPSEL_EAX 175 mov %ax,%fs 176 FAKE_MCOUNT(13*4(%esp)) 177 178 #ifdef SMP 179 MPLOCKED incl _cnt+V_TRAP 180 MP_LOCK 181 movl _cpl,%eax 182 pushl %eax /* save original cpl */ 183 pushl $0 /* dummy unit to finish intr frame */ 184 #else /* SMP */ 185 movl _cpl,%eax 186 pushl %eax 187 pushl $0 /* dummy unit to finish intr frame */ 188 incl _cnt+V_TRAP 189 #endif /* SMP */ 190 191 call _npx_intr 192 193 incb _intr_nesting_level 194 MEXITCOUNT 195 jmp _doreti 196 #else /* NNPX > 0 */ 197 pushl $0; TRAP(T_ARITHTRAP) 198 #endif /* NNPX > 0 */ 199 200 IDTVEC(align) 201 TRAP(T_ALIGNFLT) 202 203 IDTVEC(xmm) 204 pushl $0; TRAP(T_XMMFLT) 205 206 /* 207 * _alltraps entry point. Interrupts are enabled if this was a trap 208 * gate (TGT), else disabled if this was an interrupt gate (IGT). 209 * Note that int0x80_syscall is a trap gate. Only page faults 210 * use an interrupt gate. 211 * 212 * Note that all calls to MP_LOCK must occur with interrupts enabled 213 * in order to be able to take IPI's while waiting for the lock. 214 */ 215 216 SUPERALIGN_TEXT 217 .globl _alltraps 218 .type _alltraps,@function 219 _alltraps: 220 pushal 221 pushl %ds 222 pushl %es 223 pushl %fs 224 alltraps_with_regs_pushed: 225 mov $KDSEL,%ax 226 mov %ax,%ds 227 mov %ax,%es 228 MOVL_KPSEL_EAX 229 mov %ax,%fs 230 FAKE_MCOUNT(13*4(%esp)) 231 calltrap: 232 FAKE_MCOUNT(_btrap) /* init "from" _btrap -> calltrap */ 233 MPLOCKED incl _cnt+V_TRAP 234 MP_LOCK 235 movl _cpl,%ebx /* keep orig. cpl here during trap() */ 236 call _trap 237 238 /* 239 * Return via _doreti to handle ASTs. Have to change trap frame 240 * to interrupt frame. 241 */ 242 pushl %ebx /* cpl to restore */ 243 subl $4,%esp /* dummy unit to finish intr frame */ 244 incb _intr_nesting_level 245 MEXITCOUNT 246 jmp _doreti 247 248 /* 249 * SYSCALL CALL GATE (old entry point for a.out binaries) 250 * 251 * The intersegment call has been set up to specify one dummy parameter. 252 * 253 * This leaves a place to put eflags so that the call frame can be 254 * converted to a trap frame. Note that the eflags is (semi-)bogusly 255 * pushed into (what will be) tf_err and then copied later into the 256 * final spot. It has to be done this way because esp can't be just 257 * temporarily altered for the pushfl - an interrupt might come in 258 * and clobber the saved cs/eip. 259 * 260 * We do not obtain the MP lock, but the call to syscall2 might. If it 261 * does it will release the lock prior to returning. 262 */ 263 SUPERALIGN_TEXT 264 IDTVEC(syscall) 265 pushfl /* save eflags in tf_err for now */ 266 subl $4,%esp /* skip over tf_trapno */ 267 pushal 268 pushl %ds 269 pushl %es 270 pushl %fs 271 mov $KDSEL,%ax /* switch to kernel segments */ 272 mov %ax,%ds 273 mov %ax,%es 274 MOVL_KPSEL_EAX 275 mov %ax,%fs 276 movl TF_ERR(%esp),%eax /* copy saved eflags to final spot */ 277 movl %eax,TF_EFLAGS(%esp) 278 movl $7,TF_ERR(%esp) /* sizeof "lcall 7,0" */ 279 FAKE_MCOUNT(13*4(%esp)) 280 MPLOCKED incl _cnt+V_SYSCALL 281 call _syscall2 282 MEXITCOUNT 283 cli /* atomic astpending access */ 284 cmpl $0,_astpending 285 je doreti_syscall_ret 286 #ifdef SMP 287 MP_LOCK 288 #endif 289 pushl $0 /* cpl to restore */ 290 subl $4,%esp /* dummy unit for interrupt frame */ 291 movb $1,_intr_nesting_level 292 jmp _doreti 293 294 /* 295 * Call gate entry for FreeBSD ELF and Linux/NetBSD syscall (int 0x80) 296 * 297 * Even though the name says 'int0x80', this is actually a TGT (trap gate) 298 * rather then an IGT (interrupt gate). Thus interrupts are enabled on 299 * entry just as they are for a normal syscall. 300 * 301 * We do not obtain the MP lock, but the call to syscall2 might. If it 302 * does it will release the lock prior to returning. 303 */ 304 SUPERALIGN_TEXT 305 IDTVEC(int0x80_syscall) 306 subl $8,%esp /* skip over tf_trapno and tf_err */ 307 pushal 308 pushl %ds 309 pushl %es 310 pushl %fs 311 mov $KDSEL,%ax /* switch to kernel segments */ 312 mov %ax,%ds 313 mov %ax,%es 314 MOVL_KPSEL_EAX 315 mov %ax,%fs 316 movl $2,TF_ERR(%esp) /* sizeof "int 0x80" */ 317 FAKE_MCOUNT(13*4(%esp)) 318 MPLOCKED incl _cnt+V_SYSCALL 319 call _syscall2 320 MEXITCOUNT 321 cli /* atomic astpending access */ 322 cmpl $0,_astpending 323 je doreti_syscall_ret 324 #ifdef SMP 325 MP_LOCK 326 #endif 327 pushl $0 /* cpl to restore */ 328 subl $4,%esp /* dummy unit for interrupt frame */ 329 movb $1,_intr_nesting_level 330 jmp _doreti 331 332 ENTRY(fork_trampoline) 333 call _spl0 334 335 #ifdef SMP 336 cmpl $0,_switchtime 337 jne 1f 338 movl $gd_switchtime,%eax 339 addl %fs:0,%eax 340 pushl %eax 341 call _microuptime 342 popl %edx 343 movl _ticks,%eax 344 movl %eax,_switchticks 345 1: 346 #endif 347 348 /* 349 * cpu_set_fork_handler intercepts this function call to 350 * have this call a non-return function to stay in kernel mode. 351 * initproc has its own fork handler, but it does return. 352 */ 353 pushl %ebx /* arg1 */ 354 call *%esi /* function */ 355 addl $4,%esp 356 /* cut from syscall */ 357 358 /* 359 * Return via _doreti to handle ASTs. 360 */ 361 pushl $0 /* cpl to restore */ 362 subl $4,%esp /* dummy unit to finish intr frame */ 363 movb $1,_intr_nesting_level 364 MEXITCOUNT 365 jmp _doreti 366 367 368 /* 369 * Include vm86 call routines, which want to call _doreti. 370 */ 371 #include "i386/i386/vm86bios.s" 372 373 /* 374 * Include what was once config+isa-dependent code. 375 * XXX it should be in a stand-alone file. It's still icu-dependent and 376 * belongs in i386/isa. 377 */ 378 #include "i386/isa/vector.s" 379 380 /* 381 * Include what was once icu-dependent code. 382 * XXX it should be merged into this file (also move the definition of 383 * imen to vector.s or isa.c). 384 * Before including it, set up a normal asm environment so that vector.s 385 * doesn't have to know that stuff is included after it. 386 */ 387 .data 388 ALIGN_DATA 389 .text 390 SUPERALIGN_TEXT 391 #include "i386/isa/ipl.s"
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