syscall_asm.s revision 5144:0d37e3365863
1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26/* Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. */ 27/* Copyright (c) 1984, 1986, 1987, 1988, 1989, 1990 AT&T */ 28/* All Rights Reserved */ 29 30/* Copyright (c) 1987, 1988 Microsoft Corporation */ 31/* All Rights Reserved */ 32 33#pragma ident "%Z%%M% %I% %E% SMI" 34 35#include <sys/asm_linkage.h> 36#include <sys/asm_misc.h> 37#include <sys/regset.h> 38#include <sys/psw.h> 39#include <sys/x86_archext.h> 40#include <sys/machbrand.h> 41#include <sys/privregs.h> 42 43#if defined(__lint) 44 45#include <sys/types.h> 46#include <sys/thread.h> 47#include <sys/systm.h> 48 49#else /* __lint */ 50 51#include <sys/segments.h> 52#include <sys/pcb.h> 53#include <sys/trap.h> 54#include <sys/ftrace.h> 55#include <sys/traptrace.h> 56#include <sys/clock.h> 57#include <sys/panic.h> 58#include "assym.h" 59 60#endif /* __lint */ 61 62/* 63 * We implement two flavours of system call entry points 64 * 65 * - {int,lcall}/iret (i386) 66 * - sysenter/sysexit (Pentium II and beyond) 67 * 68 * The basic pattern used in the handlers is to check to see if we can 69 * do fast (simple) version of the system call; if we can't we use various 70 * C routines that handle corner cases and debugging. 71 * 72 * To reduce the amount of assembler replication, yet keep the system call 73 * implementations vaguely comprehensible, the common code in the body 74 * of the handlers is broken up into a set of preprocessor definitions 75 * below. 76 */ 77 78/* 79 * When we have SYSCALLTRACE defined, we sneak an extra 80 * predicate into a couple of tests. 81 */ 82#if defined(SYSCALLTRACE) 83#define ORL_SYSCALLTRACE(r32) \ 84 orl syscalltrace, r32 85#else 86#define ORL_SYSCALLTRACE(r32) 87#endif 88 89/* 90 * This check is false whenever we want to go fast i.e. 91 * 92 * if (code >= NSYSCALL || 93 * t->t_pre_sys || (t->t_proc_flag & TP_WATCHPT) != 0) 94 * do full version 95 * #ifdef SYSCALLTRACE 96 * if (syscalltrace) 97 * do full version 98 * #endif 99 * 100 * Preconditions: 101 * - t curthread 102 * - code contains the syscall number 103 * Postconditions: 104 * - %ecx and %edi are smashed 105 * - condition code flag ZF is cleared if pre-sys is too complex 106 */ 107#define CHECK_PRESYS_NE(t, code) \ 108 movzbl T_PRE_SYS(t), %edi; \ 109 movzwl T_PROC_FLAG(t), %ecx; \ 110 andl $TP_WATCHPT, %ecx; \ 111 orl %ecx, %edi; \ 112 cmpl $NSYSCALL, code; \ 113 setae %cl; \ 114 movzbl %cl, %ecx; \ 115 orl %ecx, %edi; \ 116 ORL_SYSCALLTRACE(%edi) 117 118/* 119 * When the brand's callback is invoked, the stack will look like this: 120 * -------------------------------------- 121 * | 'scratch space' | 122 * | user's %ebx | 123 * | user's %gs selector | 124 * | | kernel's %gs selector | 125 * | | lwp pointer | 126 * v | user return address | 127 * | callback wrapper return addr | 128 * -------------------------------------- 129 * 130 * The lx brand (at least) uses each of these fields. 131 * If the brand code returns, we assume that we are meant to execute the 132 * normal system call path. 133 */ 134#define BRAND_CALLBACK(callback_id) \ 135 subl $4, %esp /* save some scratch space */ ;\ 136 pushl %ebx /* save %ebx to use for scratch */ ;\ 137 pushl %gs /* save the user %gs */ ;\ 138 movl $KGS_SEL, %ebx ;\ 139 pushl %ebx /* push kernel's %gs */ ;\ 140 movw %bx, %gs /* switch to the kernel's %gs */ ;\ 141 movl %gs:CPU_THREAD, %ebx /* load the thread pointer */ ;\ 142 movl T_LWP(%ebx), %ebx /* load the lwp pointer */ ;\ 143 pushl %ebx /* push the lwp pointer */ ;\ 144 movl LWP_PROCP(%ebx), %ebx /* load the proc pointer */ ;\ 145 movl P_BRAND(%ebx), %ebx /* load the brand pointer */ ;\ 146 movl B_MACHOPS(%ebx), %ebx /* load the machops pointer */ ;\ 147 movl _CONST(_MUL(callback_id, CPTRSIZE))(%ebx), %ebx ;\ 148 cmpl $0, %ebx ;\ 149 je 1f ;\ 150 movl %ebx, 16(%esp) /* save callback to scratch */ ;\ 151 movl 8(%esp), %ebx /* grab the the user %gs */ ;\ 152 movw %bx, %gs /* restore the user %gs */ ;\ 153 movl 12(%esp), %ebx /* restore %ebx */ ;\ 154 pushl 20(%esp) /* push the return address */ ;\ 155 call *20(%esp) /* call callback */ ;\ 156 addl $4, %esp /* get rid of ret addr */ ;\ 1571: movl 8(%esp), %ebx /* grab the the user %gs */ ;\ 158 movw %bx, %gs /* restore the user %gs */ ;\ 159 movl 12(%esp), %ebx /* restore user's %ebx */ ;\ 160 addl $20, %esp /* restore stack ptr */ 161 162#define MSTATE_TRANSITION(from, to) \ 163 pushl $to; \ 164 pushl $from; \ 165 call syscall_mstate; \ 166 addl $0x8, %esp 167 168/* 169 * aka CPU_STATS_ADDQ(CPU, sys.syscall, 1) 170 * This must be called with interrupts or preemption disabled. 171 */ 172#define CPU_STATS_SYS_SYSCALL_INC \ 173 addl $1, %gs:CPU_STATS_SYS_SYSCALL; \ 174 adcl $0, %gs:CPU_STATS_SYS_SYSCALL+4; 175 176#if !defined(__lint) 177 178/* 179 * ASSERT(lwptoregs(lwp) == rp); 180 * 181 * this may seem obvious, but very odd things happen if this 182 * assertion is false 183 * 184 * Preconditions: 185 * -none- 186 * Postconditions (if assertion is true): 187 * %esi and %edi are smashed 188 */ 189#if defined(DEBUG) 190 191__lwptoregs_msg: 192 .string "%M%:%d lwptoregs(%p) [%p] != rp [%p]" 193 194#define ASSERT_LWPTOREGS(t, rp) \ 195 movl T_LWP(t), %esi; \ 196 movl LWP_REGS(%esi), %edi; \ 197 cmpl rp, %edi; \ 198 je 7f; \ 199 pushl rp; \ 200 pushl %edi; \ 201 pushl %esi; \ 202 pushl $__LINE__; \ 203 pushl $__lwptoregs_msg; \ 204 call panic; \ 2057: 206#else 207#define ASSERT_LWPTOREGS(t, rp) 208#endif 209 210#endif /* __lint */ 211 212/* 213 * This is an assembler version of this fragment: 214 * 215 * lwp->lwp_state = LWP_SYS; 216 * lwp->lwp_ru.sysc++; 217 * lwp->lwp_eosys = NORMALRETURN; 218 * lwp->lwp_ap = argp; 219 * 220 * Preconditions: 221 * -none- 222 * Postconditions: 223 * -none- 224 */ 225#define SET_LWP(lwp, argp) \ 226 movb $LWP_SYS, LWP_STATE(lwp); \ 227 addl $1, LWP_RU_SYSC(lwp); \ 228 adcl $0, LWP_RU_SYSC+4(lwp); \ 229 movb $NORMALRETURN, LWP_EOSYS(lwp); \ 230 movl argp, LWP_AP(lwp) 231 232/* 233 * Set up the thread, lwp, find the handler, and copy 234 * in the arguments from userland to the kernel stack. 235 * 236 * Preconditions: 237 * - %eax contains the syscall number 238 * Postconditions: 239 * - %eax contains a pointer to the sysent structure 240 * - %ecx is zeroed 241 * - %esi, %edi are smashed 242 * - %esp is SYS_DROPped ready for the syscall 243 */ 244#define SIMPLE_SYSCALL_PRESYS(t, faultlabel) \ 245 movl T_LWP(t), %esi; \ 246 movw %ax, T_SYSNUM(t); \ 247 subl $SYS_DROP, %esp; \ 248 shll $SYSENT_SIZE_SHIFT, %eax; \ 249 SET_LWP(%esi, %esp); \ 250 leal sysent(%eax), %eax; \ 251 movzbl SY_NARG(%eax), %ecx; \ 252 testl %ecx, %ecx; \ 253 jz 4f; \ 254 movl %esp, %edi; \ 255 movl SYS_DROP + REGOFF_UESP(%esp), %esi; \ 256 movl $faultlabel, T_LOFAULT(t); \ 257 addl $4, %esi; \ 258 rep; \ 259 smovl; \ 260 movl %ecx, T_LOFAULT(t); \ 2614: 262 263/* 264 * Check to see if a simple return is possible i.e. 265 * 266 * if ((t->t_post_sys_ast | syscalltrace) != 0) 267 * do full version; 268 * 269 * Preconditions: 270 * - t is curthread 271 * Postconditions: 272 * - condition code NE is set if post-sys is too complex 273 * - rtmp is zeroed if it isn't (we rely on this!) 274 */ 275#define CHECK_POSTSYS_NE(t, rtmp) \ 276 xorl rtmp, rtmp; \ 277 ORL_SYSCALLTRACE(rtmp); \ 278 orl T_POST_SYS_AST(t), rtmp; \ 279 cmpl $0, rtmp 280 281/* 282 * Fix up the lwp, thread, and eflags for a successful return 283 * 284 * Preconditions: 285 * - zwreg contains zero 286 * Postconditions: 287 * - %esp has been unSYS_DROPped 288 * - %esi is smashed (points to lwp) 289 */ 290#define SIMPLE_SYSCALL_POSTSYS(t, zwreg) \ 291 movl T_LWP(t), %esi; \ 292 addl $SYS_DROP, %esp; \ 293 movw zwreg, T_SYSNUM(t); \ 294 movb $LWP_USER, LWP_STATE(%esi); \ 295 andb $_CONST(0xffff - PS_C), REGOFF_EFL(%esp) 296 297/* 298 * System call handler. This is the destination of both the call 299 * gate (lcall 0x27) _and_ the interrupt gate (int 0x91). For our purposes, 300 * there are two significant differences between an interrupt gate and a call 301 * gate: 302 * 303 * 1) An interrupt gate runs the handler with interrupts disabled, whereas a 304 * call gate runs the handler with whatever EFLAGS settings were in effect at 305 * the time of the call. 306 * 307 * 2) An interrupt gate pushes the contents of the EFLAGS register at the time 308 * of the interrupt onto the stack, whereas a call gate does not. 309 * 310 * Because we use the following code sequence to handle system calls made from 311 * _both_ a call gate _and_ an interrupt gate, these two differences must be 312 * respected. In regards to number 1) above, the handler must ensure that a sane 313 * EFLAGS snapshot is stored on the stack so that when the kernel returns back 314 * to the user via iret (which returns to user with the EFLAGS value saved on 315 * the stack), interrupts are re-enabled. 316 * 317 * In regards to number 2) above, the handler must always put a current snapshot 318 * of EFLAGS onto the stack in the appropriate place. If we came in via an 319 * interrupt gate, we will be clobbering the EFLAGS value that was pushed by 320 * the interrupt gate. This is OK, as the only bit that was changed by the 321 * hardware was the IE (interrupt enable) bit, which for an interrupt gate is 322 * now off. If we were to do nothing, the stack would contain an EFLAGS with 323 * IE off, resulting in us eventually returning back to the user with interrupts 324 * disabled. The solution is to turn on the IE bit in the EFLAGS value saved on 325 * the stack. 326 * 327 * Another subtlety which deserves mention is the difference between the two 328 * descriptors. The call gate descriptor is set to instruct the hardware to copy 329 * one parameter from the user stack to the kernel stack, whereas the interrupt 330 * gate descriptor doesn't use the parameter passing mechanism at all. The 331 * kernel doesn't actually use the parameter that is copied by the hardware; the 332 * only reason it does this is so that there is a space on the stack large 333 * enough to hold an EFLAGS register value, which happens to be in the correct 334 * place for use by iret when we go back to userland. How convenient. 335 * 336 * Stack frame description in syscall() and callees. 337 * 338 * |------------| 339 * | regs | +(8*4)+4 registers 340 * |------------| 341 * | 8 args | <- %esp MAXSYSARGS (currently 8) arguments 342 * |------------| 343 * 344 */ 345#define SYS_DROP _CONST(_MUL(MAXSYSARGS, 4)) 346 347#if defined(__lint) 348 349/*ARGSUSED*/ 350void 351sys_call() 352{} 353 354void 355_allsyscalls() 356{} 357 358size_t _allsyscalls_size; 359 360#else /* __lint */ 361 362 ENTRY_NP2(brand_sys_call, _allsyscalls) 363 BRAND_CALLBACK(BRAND_CB_SYSCALL) 364 365 ALTENTRY(sys_call) 366 / on entry eax = system call number 367 368 / set up the stack to look as in reg.h 369 subl $8, %esp / pad the stack with ERRCODE and TRAPNO 370 371 SYSCALL_PUSH 372 373#ifdef TRAPTRACE 374 TRACE_PTR(%edi, %ebx, %ebx, %ecx, $TT_SYSCALL) / Uses labels "8" and "9" 375 TRACE_REGS(%edi, %esp, %ebx, %ecx) / Uses label "9" 376 pushl %eax 377 TRACE_STAMP(%edi) / Clobbers %eax, %edx, uses "9" 378 popl %eax 379 movl %eax, TTR_SYSNUM(%edi) 380#endif 381 382_watch_do_syscall: 383 movl %esp, %ebp 384 385 / Interrupts may be enabled here, so we must make sure this thread 386 / doesn't migrate off the CPU while it updates the CPU stats. 387 / 388 / XXX This is only true if we got here via call gate thru the LDT for 389 / old style syscalls. Perhaps this preempt++-- will go away soon? 390 movl %gs:CPU_THREAD, %ebx 391 addb $1, T_PREEMPT(%ebx) 392 CPU_STATS_SYS_SYSCALL_INC 393 subb $1, T_PREEMPT(%ebx) 394 395 ENABLE_INTR_FLAGS 396 397 pushl %eax / preserve across mstate call 398 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 399 popl %eax 400 401 movl %gs:CPU_THREAD, %ebx 402 403 ASSERT_LWPTOREGS(%ebx, %esp) 404 405 CHECK_PRESYS_NE(%ebx, %eax) 406 jne _full_syscall_presys 407 SIMPLE_SYSCALL_PRESYS(%ebx, _syscall_fault) 408 409_syslcall_call: 410 call *SY_CALLC(%eax) 411 412_syslcall_done: 413 CHECK_POSTSYS_NE(%ebx, %ecx) 414 jne _full_syscall_postsys 415 SIMPLE_SYSCALL_POSTSYS(%ebx, %cx) 416 movl %eax, REGOFF_EAX(%esp) 417 movl %edx, REGOFF_EDX(%esp) 418 419 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 420 421 / 422 / get back via iret 423 / 424 CLI(%edx) 425 jmp sys_rtt_syscall 426 427_full_syscall_presys: 428 movl T_LWP(%ebx), %esi 429 subl $SYS_DROP, %esp 430 movb $LWP_SYS, LWP_STATE(%esi) 431 pushl %esp 432 pushl %ebx 433 call syscall_entry 434 addl $8, %esp 435 jmp _syslcall_call 436 437_full_syscall_postsys: 438 addl $SYS_DROP, %esp 439 pushl %edx 440 pushl %eax 441 pushl %ebx 442 call syscall_exit 443 addl $12, %esp 444 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 445 jmp _sys_rtt 446 447_syscall_fault: 448 push $0xe / EFAULT 449 call set_errno 450 addl $4, %esp 451 xorl %eax, %eax / fake syscall_err() 452 xorl %edx, %edx 453 jmp _syslcall_done 454 SET_SIZE(sys_call) 455 SET_SIZE(brand_sys_call) 456 457#endif /* __lint */ 458 459/* 460 * System call handler via the sysenter instruction 461 * 462 * Here's how syscall entry usually works (see sys_call for details). 463 * 464 * There, the caller (lcall or int) in userland has arranged that: 465 * 466 * - %eax contains the syscall number 467 * - the user stack contains the args to the syscall 468 * 469 * Normally the lcall instruction into the call gate causes the processor 470 * to push %ss, %esp, <top-of-stack>, %cs, %eip onto the kernel stack. 471 * The sys_call handler then leaves space for r_trapno and r_err, and 472 * pusha's {%eax, %ecx, %edx, %ebx, %esp, %ebp, %esi, %edi}, followed 473 * by %ds, %es, %fs and %gs to capture a 'struct regs' on the stack. 474 * Then the kernel sets %ds, %es and %gs to kernel selectors, and finally 475 * extracts %efl and puts it into r_efl (which happens to live at the offset 476 * that <top-of-stack> was copied into). Note that the value in r_efl has 477 * the IF (interrupt enable) flag turned on. (The int instruction into the 478 * interrupt gate does essentially the same thing, only instead of 479 * <top-of-stack> we get eflags - see comment above.) 480 * 481 * In the sysenter case, things are a lot more primitive. 482 * 483 * The caller in userland has arranged that: 484 * 485 * - %eax contains the syscall number 486 * - %ecx contains the user %esp 487 * - %edx contains the return %eip 488 * - the user stack contains the args to the syscall 489 * 490 * e.g. 491 * <args on the stack> 492 * mov $SYS_callnum, %eax 493 * mov $1f, %edx / return %eip 494 * mov %esp, %ecx / return %esp 495 * sysenter 496 * 1: 497 * 498 * Hardware and (privileged) initialization code have arranged that by 499 * the time the sysenter instructions completes: 500 * 501 * - %eip is pointing to sys_sysenter (below). 502 * - %cs and %ss are set to kernel text and stack (data) selectors. 503 * - %esp is pointing at the lwp's stack 504 * - Interrupts have been disabled. 505 * 506 * The task for the sysenter handler is: 507 * 508 * - recreate the same regs structure on the stack and the same 509 * kernel state as if we'd come in on an lcall 510 * - do the normal work of a syscall 511 * - execute the system call epilogue, use sysexit to return to userland. 512 * 513 * Note that we are unable to return both "rvals" to userland with this 514 * call, as %edx is used by the sysexit instruction. 515 * 516 * One final complication in this routine is its interaction with 517 * single-stepping in a debugger. For most of the system call mechanisms, 518 * the CPU automatically clears the single-step flag before we enter the 519 * kernel. The sysenter mechanism does not clear the flag, so a user 520 * single-stepping through a libc routine may suddenly find him/herself 521 * single-stepping through the kernel. To detect this, kmdb compares the 522 * trap %pc to the [brand_]sys_enter addresses on each single-step trap. 523 * If it finds that we have single-stepped to a sysenter entry point, it 524 * explicitly clears the flag and executes the sys_sysenter routine. 525 * 526 * One final complication in this final complication is the fact that we 527 * have two different entry points for sysenter: brand_sys_sysenter and 528 * sys_sysenter. If we enter at brand_sys_sysenter and start single-stepping 529 * through the kernel with kmdb, we will eventually hit the instruction at 530 * sys_sysenter. kmdb cannot distinguish between that valid single-step 531 * and the undesirable one mentioned above. To avoid this situation, we 532 * simply add a jump over the instruction at sys_sysenter to make it 533 * impossible to single-step to it. 534 */ 535#if defined(__lint) 536 537void 538sys_sysenter() 539{} 540 541#else /* __lint */ 542 543 ENTRY_NP(brand_sys_sysenter) 544 pushl %edx 545 BRAND_CALLBACK(BRAND_CB_SYSENTER) 546 popl %edx 547 /* 548 * Jump over sys_sysenter to allow single-stepping as described 549 * above. 550 */ 551 ja 1f 552 553 ALTENTRY(sys_sysenter) 554 nop 5551: 556 / 557 / do what the call gate would've done to the stack .. 558 / 559 pushl $UDS_SEL / (really %ss, but it's the same ..) 560 pushl %ecx / userland makes this a copy of %esp 561 pushfl 562 orl $PS_IE, (%esp) / turn interrupts on when we return to user 563 pushl $UCS_SEL 564 pushl %edx / userland makes this a copy of %eip 565 / 566 / done. finish building the stack frame 567 / 568 subl $8, %esp / leave space for ERR and TRAPNO 569 570 SYSENTER_PUSH 571 572#ifdef TRAPTRACE 573 TRACE_PTR(%edi, %ebx, %ebx, %ecx, $TT_SYSENTER) / uses labels 8 and 9 574 TRACE_REGS(%edi, %esp, %ebx, %ecx) / uses label 9 575 pushl %eax 576 TRACE_STAMP(%edi) / clobbers %eax, %edx, uses label 9 577 popl %eax 578 movl %eax, TTR_SYSNUM(%edi) 579#endif 580 movl %esp, %ebp 581 582 CPU_STATS_SYS_SYSCALL_INC 583 584 ENABLE_INTR_FLAGS 585 586 pushl %eax / preserve across mstate call 587 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 588 popl %eax 589 590 movl %gs:CPU_THREAD, %ebx 591 592 ASSERT_LWPTOREGS(%ebx, %esp) 593 594 CHECK_PRESYS_NE(%ebx, %eax) 595 jne _full_syscall_presys 596 SIMPLE_SYSCALL_PRESYS(%ebx, _syscall_fault) 597 598_sysenter_call: 599 call *SY_CALLC(%eax) 600 601_sysenter_done: 602 CHECK_POSTSYS_NE(%ebx, %ecx) 603 jne _full_syscall_postsys 604 SIMPLE_SYSCALL_POSTSYS(%ebx, %cx) 605 / 606 / sysexit uses %edx to restore %eip, so we can't use it 607 / to return a value, sigh. 608 / 609 movl %eax, REGOFF_EAX(%esp) 610 / movl %edx, REGOFF_EDX(%esp) 611 612 / Interrupts will be turned on by the 'sti' executed just before 613 / sysexit. The following ensures that restoring the user's EFLAGS 614 / doesn't enable interrupts too soon. 615 andl $_BITNOT(PS_IE), REGOFF_EFL(%esp) 616 617 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 618 619 cli 620 621 SYSCALL_POP 622 623 popl %edx / sysexit: %edx -> %eip 624 addl $4, %esp / get CS off the stack 625 popfl / EFL 626 popl %ecx / sysexit: %ecx -> %esp 627 sti 628 sysexit 629 SET_SIZE(sys_sysenter) 630 SET_SIZE(brand_sys_sysenter) 631 632#endif /* __lint */ 633 634#if defined(__lint) 635/* 636 * System call via an int80. This entry point is only used by the Linux 637 * application environment. Unlike the sysenter path, there is no default 638 * action to take if no callback is registered for this process. 639 */ 640void 641sys_int80() 642{} 643 644#else /* __lint */ 645 646 ENTRY_NP(brand_sys_int80) 647 BRAND_CALLBACK(BRAND_CB_INT80) 648 649 ALTENTRY(sys_int80) 650 /* 651 * We hit an int80, but this process isn't of a brand with an int80 652 * handler. Bad process! Make it look as if the INT failed. 653 * Modify %eip to point before the INT, push the expected error 654 * code and fake a GP fault. 655 * 656 */ 657 subl $2, (%esp) /* int insn 2-bytes */ 658 pushl $_CONST(_MUL(T_INT80, GATE_DESC_SIZE) + 2) 659 jmp gptrap / GP fault 660 SET_SIZE(sys_int80) 661 SET_SIZE(brand_sys_int80) 662 663/* 664 * Declare a uintptr_t which covers the entire pc range of syscall 665 * handlers for the stack walkers that need this. 666 */ 667 .align CPTRSIZE 668 .globl _allsyscalls_size 669 .type _allsyscalls_size, @object 670_allsyscalls_size: 671 .NWORD . - _allsyscalls 672 SET_SIZE(_allsyscalls_size) 673 674#endif /* __lint */ 675 676/* 677 * These are the thread context handlers for lwps using sysenter/sysexit. 678 */ 679 680#if defined(__lint) 681 682/*ARGSUSED*/ 683void 684sep_save(void *ksp) 685{} 686 687/*ARGSUSED*/ 688void 689sep_restore(void *ksp) 690{} 691 692#else /* __lint */ 693 694 /* 695 * setting this value to zero as we switch away causes the 696 * stack-pointer-on-sysenter to be NULL, ensuring that we 697 * don't silently corrupt another (preempted) thread stack 698 * when running an lwp that (somehow) didn't get sep_restore'd 699 */ 700 ENTRY_NP(sep_save) 701 xorl %edx, %edx 702 xorl %eax, %eax 703 movl $MSR_INTC_SEP_ESP, %ecx 704 wrmsr 705 ret 706 SET_SIZE(sep_save) 707 708 /* 709 * Update the kernel stack pointer as we resume onto this cpu. 710 */ 711 ENTRY_NP(sep_restore) 712 movl 4(%esp), %eax /* per-lwp kernel sp */ 713 xorl %edx, %edx 714 movl $MSR_INTC_SEP_ESP, %ecx 715 wrmsr 716 ret 717 SET_SIZE(sep_restore) 718 719#endif /* __lint */ 720 721/* 722 * Call syscall(). Called from trap() on watchpoint at lcall 0,7 723 */ 724 725#if defined(__lint) 726 727void 728watch_syscall(void) 729{} 730 731#else /* __lint */ 732 733 ENTRY_NP(watch_syscall) 734 CLI(%eax) 735 movl %gs:CPU_THREAD, %ebx 736 movl T_STACK(%ebx), %esp / switch to the thread stack 737 movl REGOFF_EAX(%esp), %eax / recover original syscall# 738 jmp _watch_do_syscall 739 SET_SIZE(watch_syscall) 740 741#endif /* __lint */ 742