Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/i386/xen/exception.s
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1 /*- 2 * Copyright (c) 1989, 1990 William F. Jolitz. 3 * Copyright (c) 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 4. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * $FreeBSD: releng/10.0/sys/i386/xen/exception.s 255040 2013-08-29 19:52:18Z gibbs $ 31 */ 32 33 #include "opt_apic.h" 34 #include "opt_npx.h" 35 36 #include <machine/asmacros.h> 37 #include <machine/psl.h> 38 #include <machine/trap.h> 39 40 #include "assym.s" 41 42 #define SEL_RPL_MASK 0x0002 43 #define __HYPERVISOR_iret 23 44 45 /* Offsets into shared_info_t. */ 46 47 #define evtchn_upcall_pending /* 0 */ 48 #define evtchn_upcall_mask 1 49 50 #define sizeof_vcpu_shift 6 51 52 53 #ifdef SMP 54 #define GET_VCPU_INFO(reg) movl PCPU(CPUID),reg ; \ 55 shl $sizeof_vcpu_shift,reg ; \ 56 addl HYPERVISOR_shared_info,reg 57 #else 58 #define GET_VCPU_INFO(reg) movl HYPERVISOR_shared_info,reg 59 #endif 60 61 #define __DISABLE_INTERRUPTS(reg) movb $1,evtchn_upcall_mask(reg) 62 #define __ENABLE_INTERRUPTS(reg) movb $0,evtchn_upcall_mask(reg) 63 #define DISABLE_INTERRUPTS(reg) GET_VCPU_INFO(reg) ; \ 64 __DISABLE_INTERRUPTS(reg) 65 #define ENABLE_INTERRUPTS(reg) GET_VCPU_INFO(reg) ; \ 66 __ENABLE_INTERRUPTS(reg) 67 #define __TEST_PENDING(reg) testb $0xFF,evtchn_upcall_pending(reg) 68 69 #define POPA \ 70 popl %edi; \ 71 popl %esi; \ 72 popl %ebp; \ 73 popl %ebx; \ 74 popl %ebx; \ 75 popl %edx; \ 76 popl %ecx; \ 77 popl %eax; 78 79 .text 80 81 /*****************************************************************************/ 82 /* Trap handling */ 83 /*****************************************************************************/ 84 /* 85 * Trap and fault vector routines. 86 * 87 * Most traps are 'trap gates', SDT_SYS386TGT. A trap gate pushes state on 88 * the stack that mostly looks like an interrupt, but does not disable 89 * interrupts. A few of the traps we are use are interrupt gates, 90 * SDT_SYS386IGT, which are nearly the same thing except interrupts are 91 * disabled on entry. 92 * 93 * The cpu will push a certain amount of state onto the kernel stack for 94 * the current process. The amount of state depends on the type of trap 95 * and whether the trap crossed rings or not. See i386/include/frame.h. 96 * At the very least the current EFLAGS (status register, which includes 97 * the interrupt disable state prior to the trap), the code segment register, 98 * and the return instruction pointer are pushed by the cpu. The cpu 99 * will also push an 'error' code for certain traps. We push a dummy 100 * error code for those traps where the cpu doesn't in order to maintain 101 * a consistent frame. We also push a contrived 'trap number'. 102 * 103 * The cpu does not push the general registers, we must do that, and we 104 * must restore them prior to calling 'iret'. The cpu adjusts the %cs and 105 * %ss segment registers, but does not mess with %ds, %es, or %fs. Thus we 106 * must load them with appropriate values for supervisor mode operation. 107 */ 108 109 MCOUNT_LABEL(user) 110 MCOUNT_LABEL(btrap) 111 112 #define TRAP(a) pushl $(a) ; jmp alltraps 113 114 IDTVEC(div) 115 pushl $0; TRAP(T_DIVIDE) 116 IDTVEC(dbg) 117 pushl $0; TRAP(T_TRCTRAP) 118 IDTVEC(nmi) 119 pushl $0; TRAP(T_NMI) 120 IDTVEC(bpt) 121 pushl $0; TRAP(T_BPTFLT) 122 IDTVEC(ofl) 123 pushl $0; TRAP(T_OFLOW) 124 IDTVEC(bnd) 125 pushl $0; TRAP(T_BOUND) 126 IDTVEC(ill) 127 pushl $0; TRAP(T_PRIVINFLT) 128 IDTVEC(dna) 129 pushl $0; TRAP(T_DNA) 130 IDTVEC(fpusegm) 131 pushl $0; TRAP(T_FPOPFLT) 132 IDTVEC(tss) 133 TRAP(T_TSSFLT) 134 IDTVEC(missing) 135 TRAP(T_SEGNPFLT) 136 IDTVEC(stk) 137 TRAP(T_STKFLT) 138 IDTVEC(prot) 139 TRAP(T_PROTFLT) 140 IDTVEC(page) 141 TRAP(T_PAGEFLT) 142 IDTVEC(mchk) 143 pushl $0; TRAP(T_MCHK) 144 IDTVEC(rsvd) 145 pushl $0; TRAP(T_RESERVED) 146 IDTVEC(fpu) 147 pushl $0; TRAP(T_ARITHTRAP) 148 IDTVEC(align) 149 TRAP(T_ALIGNFLT) 150 IDTVEC(xmm) 151 pushl $0; TRAP(T_XMMFLT) 152 153 IDTVEC(hypervisor_callback) 154 pushl $0; 155 pushl $0; 156 pushal 157 pushl %ds 158 pushl %es 159 pushl %fs 160 upcall_with_regs_pushed: 161 SET_KERNEL_SREGS 162 FAKE_MCOUNT(TF_EIP(%esp)) 163 call_evtchn_upcall: 164 movl TF_EIP(%esp),%eax 165 cmpl $scrit,%eax 166 jb 10f 167 cmpl $ecrit,%eax 168 jb critical_region_fixup 169 170 10: pushl %esp 171 call xen_intr_handle_upcall 172 addl $4,%esp 173 174 /* 175 * Return via doreti to handle ASTs. 176 */ 177 MEXITCOUNT 178 jmp doreti 179 180 181 hypervisor_callback_pending: 182 DISABLE_INTERRUPTS(%esi) /* cli */ 183 jmp 10b 184 /* 185 * alltraps entry point. Interrupts are enabled if this was a trap 186 * gate (TGT), else disabled if this was an interrupt gate (IGT). 187 * Note that int0x80_syscall is a trap gate. Only page faults 188 * use an interrupt gate. 189 */ 190 SUPERALIGN_TEXT 191 .globl alltraps 192 .type alltraps,@function 193 alltraps: 194 pushal 195 pushl %ds 196 pushl %es 197 pushl %fs 198 199 alltraps_with_regs_pushed: 200 SET_KERNEL_SREGS 201 FAKE_MCOUNT(TF_EIP(%esp)) 202 203 calltrap: 204 push %esp 205 call trap 206 add $4, %esp 207 208 /* 209 * Return via doreti to handle ASTs. 210 */ 211 MEXITCOUNT 212 jmp doreti 213 214 /* 215 * SYSCALL CALL GATE (old entry point for a.out binaries) 216 * 217 * The intersegment call has been set up to specify one dummy parameter. 218 * 219 * This leaves a place to put eflags so that the call frame can be 220 * converted to a trap frame. Note that the eflags is (semi-)bogusly 221 * pushed into (what will be) tf_err and then copied later into the 222 * final spot. It has to be done this way because esp can't be just 223 * temporarily altered for the pushfl - an interrupt might come in 224 * and clobber the saved cs/eip. 225 */ 226 SUPERALIGN_TEXT 227 IDTVEC(lcall_syscall) 228 pushfl /* save eflags */ 229 popl 8(%esp) /* shuffle into tf_eflags */ 230 pushl $7 /* sizeof "lcall 7,0" */ 231 subl $4,%esp /* skip over tf_trapno */ 232 pushal 233 pushl %ds 234 pushl %es 235 pushl %fs 236 SET_KERNEL_SREGS 237 FAKE_MCOUNT(TF_EIP(%esp)) 238 pushl %esp 239 call syscall 240 add $4, %esp 241 MEXITCOUNT 242 jmp doreti 243 244 /* 245 * Call gate entry for FreeBSD ELF and Linux/NetBSD syscall (int 0x80) 246 * 247 * Even though the name says 'int0x80', this is actually a TGT (trap gate) 248 * rather then an IGT (interrupt gate). Thus interrupts are enabled on 249 * entry just as they are for a normal syscall. 250 */ 251 SUPERALIGN_TEXT 252 IDTVEC(int0x80_syscall) 253 pushl $2 /* sizeof "int 0x80" */ 254 pushl $0xBEEF /* for debug */ 255 pushal 256 pushl %ds 257 pushl %es 258 pushl %fs 259 SET_KERNEL_SREGS 260 FAKE_MCOUNT(TF_EIP(%esp)) 261 pushl %esp 262 call syscall 263 add $4, %esp 264 MEXITCOUNT 265 jmp doreti 266 267 ENTRY(fork_trampoline) 268 pushl %esp /* trapframe pointer */ 269 pushl %ebx /* arg1 */ 270 pushl %esi /* function */ 271 call fork_exit 272 addl $12,%esp 273 /* cut from syscall */ 274 275 /* 276 * Return via doreti to handle ASTs. 277 */ 278 MEXITCOUNT 279 jmp doreti 280 281 282 /* 283 * To efficiently implement classification of trap and interrupt handlers 284 * for profiling, there must be only trap handlers between the labels btrap 285 * and bintr, and only interrupt handlers between the labels bintr and 286 * eintr. This is implemented (partly) by including files that contain 287 * some of the handlers. Before including the files, set up a normal asm 288 * environment so that the included files doen't need to know that they are 289 * included. 290 */ 291 292 .data 293 .p2align 4 294 .text 295 SUPERALIGN_TEXT 296 MCOUNT_LABEL(bintr) 297 298 #ifdef DEV_APIC 299 .data 300 .p2align 4 301 .text 302 SUPERALIGN_TEXT 303 304 #include <i386/i386/apic_vector.s> 305 #endif 306 307 .data 308 .p2align 4 309 .text 310 SUPERALIGN_TEXT 311 #include <i386/i386/vm86bios.s> 312 313 .text 314 MCOUNT_LABEL(eintr) 315 316 /* 317 * void doreti(struct trapframe) 318 * 319 * Handle return from interrupts, traps and syscalls. 320 */ 321 .text 322 SUPERALIGN_TEXT 323 .type doreti,@function 324 doreti: 325 FAKE_MCOUNT($bintr) /* init "from" bintr -> doreti */ 326 doreti_next: 327 #ifdef notyet 328 /* 329 * Check if ASTs can be handled now. PSL_VM must be checked first 330 * since segment registers only have an RPL in non-VM86 mode. 331 */ 332 testl $PSL_VM,TF_EFLAGS(%esp) /* are we in vm86 mode? */ 333 jz doreti_notvm86 334 movl PCPU(CURPCB),%ecx 335 testl $PCB_VM86CALL,PCB_FLAGS(%ecx) /* are we in a vm86 call? */ 336 jz doreti_ast /* can handle ASTS now if not */ 337 jmp doreti_exit 338 339 doreti_notvm86: 340 #endif 341 testb $SEL_RPL_MASK,TF_CS(%esp) /* are we returning to user mode? */ 342 jz doreti_exit /* can't handle ASTs now if not */ 343 344 doreti_ast: 345 /* 346 * Check for ASTs atomically with returning. Disabling CPU 347 * interrupts provides sufficient locking even in the SMP case, 348 * since we will be informed of any new ASTs by an IPI. 349 */ 350 DISABLE_INTERRUPTS(%esi) /* cli */ 351 movl PCPU(CURTHREAD),%eax 352 testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%eax) 353 je doreti_exit 354 ENABLE_INTERRUPTS(%esi) /* sti */ 355 pushl %esp /* pass a pointer to the trapframe */ 356 call ast 357 add $4,%esp 358 jmp doreti_ast 359 360 /* 361 * doreti_exit: pop registers, iret. 362 * 363 * The segment register pop is a special case, since it may 364 * fault if (for example) a sigreturn specifies bad segment 365 * registers. The fault is handled in trap.c. 366 */ 367 doreti_exit: 368 ENABLE_INTERRUPTS(%esi) # reenable event callbacks (sti) 369 370 .globl scrit 371 scrit: 372 __TEST_PENDING(%esi) 373 jnz hypervisor_callback_pending /* More to go */ 374 375 MEXITCOUNT 376 377 .globl doreti_popl_fs 378 doreti_popl_fs: 379 popl %fs 380 .globl doreti_popl_es 381 doreti_popl_es: 382 popl %es 383 .globl doreti_popl_ds 384 doreti_popl_ds: 385 popl %ds 386 387 /* 388 * This is important: as nothing is atomic over here (we can get 389 * interrupted any time), we use the critical_region_fixup() in 390 * order to figure out where out stack is. Therefore, do NOT use 391 * 'popal' here without fixing up the table! 392 */ 393 POPA 394 addl $8,%esp 395 .globl doreti_iret 396 doreti_iret: 397 jmp hypercall_page + (__HYPERVISOR_iret * 32) 398 .globl ecrit 399 ecrit: 400 /* 401 * doreti_iret_fault and friends. Alternative return code for 402 * the case where we get a fault in the doreti_exit code 403 * above. trap() (i386/i386/trap.c) catches this specific 404 * case, sends the process a signal and continues in the 405 * corresponding place in the code below. 406 */ 407 ALIGN_TEXT 408 .globl doreti_iret_fault 409 doreti_iret_fault: 410 subl $8,%esp 411 pushal 412 pushl %ds 413 .globl doreti_popl_ds_fault 414 doreti_popl_ds_fault: 415 pushl %es 416 .globl doreti_popl_es_fault 417 doreti_popl_es_fault: 418 pushl %fs 419 .globl doreti_popl_fs_fault 420 doreti_popl_fs_fault: 421 movl $0,TF_ERR(%esp) /* XXX should be the error code */ 422 movl $T_PROTFLT,TF_TRAPNO(%esp) 423 jmp alltraps_with_regs_pushed 424 425 /* 426 # [How we do the fixup]. We want to merge the current stack frame with the 427 # just-interrupted frame. How we do this depends on where in the critical 428 # region the interrupted handler was executing, and so how many saved 429 # registers are in each frame. We do this quickly using the lookup table 430 # 'critical_fixup_table'. For each byte offset in the critical region, it 431 # provides the number of bytes which have already been popped from the 432 # interrupted stack frame. 433 */ 434 435 .globl critical_region_fixup 436 critical_region_fixup: 437 addl $critical_fixup_table-scrit,%eax 438 movzbl (%eax),%eax # %eax contains num bytes popped 439 movl %esp,%esi 440 add %eax,%esi # %esi points at end of src region 441 movl %esp,%edi 442 add $0x40,%edi # %edi points at end of dst region 443 movl %eax,%ecx 444 shr $2,%ecx # convert bytes to words 445 je 16f # skip loop if nothing to copy 446 15: subl $4,%esi # pre-decrementing copy loop 447 subl $4,%edi 448 movl (%esi),%eax 449 movl %eax,(%edi) 450 loop 15b 451 16: movl %edi,%esp # final %edi is top of merged stack 452 jmp hypervisor_callback_pending 453 454 455 critical_fixup_table: 456 .byte 0x0,0x0,0x0 #testb $0x1,(%esi) 457 .byte 0x0,0x0,0x0,0x0,0x0,0x0 #jne ea 458 .byte 0x0,0x0 #pop %fs 459 .byte 0x04 #pop %es 460 .byte 0x08 #pop %ds 461 .byte 0x0c #pop %edi 462 .byte 0x10 #pop %esi 463 .byte 0x14 #pop %ebp 464 .byte 0x18 #pop %ebx 465 .byte 0x1c #pop %ebx 466 .byte 0x20 #pop %edx 467 .byte 0x24 #pop %ecx 468 .byte 0x28 #pop %eax 469 .byte 0x2c,0x2c,0x2c #add $0x8,%esp 470 #if 0 471 .byte 0x34 #iret 472 #endif 473 .byte 0x34,0x34,0x34,0x34,0x34 #HYPERVISOR_iret 474 475 476 /* # Hypervisor uses this for application faults while it executes.*/ 477 ENTRY(failsafe_callback) 478 pushal 479 call xen_failsafe_handler 480 /*# call install_safe_pf_handler */ 481 movl 28(%esp),%ebx 482 1: movl %ebx,%ds 483 movl 32(%esp),%ebx 484 2: movl %ebx,%es 485 movl 36(%esp),%ebx 486 3: movl %ebx,%fs 487 movl 40(%esp),%ebx 488 4: movl %ebx,%gs 489 /*# call install_normal_pf_handler */ 490 popal 491 addl $12,%esp 492 iret 493 494
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