syscall_asm_amd64.s revision 11685:95082903303d
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 2010 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26#include <sys/asm_linkage.h> 27#include <sys/asm_misc.h> 28#include <sys/regset.h> 29#include <sys/privregs.h> 30#include <sys/psw.h> 31#include <sys/machbrand.h> 32 33#if defined(__lint) 34 35#include <sys/types.h> 36#include <sys/thread.h> 37#include <sys/systm.h> 38 39#else /* __lint */ 40 41#include <sys/segments.h> 42#include <sys/pcb.h> 43#include <sys/trap.h> 44#include <sys/ftrace.h> 45#include <sys/traptrace.h> 46#include <sys/clock.h> 47#include <sys/model.h> 48#include <sys/panic.h> 49 50#if defined(__xpv) 51#include <sys/hypervisor.h> 52#endif 53 54#include "assym.h" 55 56#endif /* __lint */ 57 58/* 59 * We implement five flavours of system call entry points 60 * 61 * - syscall/sysretq (amd64 generic) 62 * - syscall/sysretl (i386 plus SYSC bit) 63 * - sysenter/sysexit (i386 plus SEP bit) 64 * - int/iret (i386 generic) 65 * - lcall/iret (i386 generic) 66 * 67 * The current libc included in Solaris uses int/iret as the base unoptimized 68 * kernel entry method. Older libc implementations and legacy binaries may use 69 * the lcall call gate, so it must continue to be supported. 70 * 71 * System calls that use an lcall call gate are processed in trap() via a 72 * segment-not-present trap, i.e. lcalls are extremely slow(!). 73 * 74 * The basic pattern used in the 32-bit SYSC handler at this point in time is 75 * to have the bare minimum of assembler, and get to the C handlers as 76 * quickly as possible. 77 * 78 * The 64-bit handler is much closer to the sparcv9 handler; that's 79 * because of passing arguments in registers. The 32-bit world still 80 * passes arguments on the stack -- that makes that handler substantially 81 * more complex. 82 * 83 * The two handlers share a few code fragments which are broken 84 * out into preprocessor macros below. 85 * 86 * XX64 come back and speed all this up later. The 32-bit stuff looks 87 * especially easy to speed up the argument copying part .. 88 * 89 * 90 * Notes about segment register usage (c.f. the 32-bit kernel) 91 * 92 * In the 32-bit kernel, segment registers are dutifully saved and 93 * restored on all mode transitions because the kernel uses them directly. 94 * When the processor is running in 64-bit mode, segment registers are 95 * largely ignored. 96 * 97 * %cs and %ss 98 * controlled by the hardware mechanisms that make mode transitions 99 * 100 * The remaining segment registers have to either be pointing at a valid 101 * descriptor i.e. with the 'present' bit set, or they can NULL descriptors 102 * 103 * %ds and %es 104 * always ignored 105 * 106 * %fs and %gs 107 * fsbase and gsbase are used to control the place they really point at. 108 * The kernel only depends on %gs, and controls its own gsbase via swapgs 109 * 110 * Note that loading segment registers is still costly because the GDT 111 * lookup still happens (this is because the hardware can't know that we're 112 * not setting up these segment registers for a 32-bit program). Thus we 113 * avoid doing this in the syscall path, and defer them to lwp context switch 114 * handlers, so the register values remain virtualized to the lwp. 115 */ 116 117#if defined(SYSCALLTRACE) 118#define ORL_SYSCALLTRACE(r32) \ 119 orl syscalltrace(%rip), r32 120#else 121#define ORL_SYSCALLTRACE(r32) 122#endif 123 124/* 125 * In the 32-bit kernel, we do absolutely nothing before getting into the 126 * brand callback checks. In 64-bit land, we do swapgs and then come here. 127 * We assume that the %rsp- and %r15-stashing fields in the CPU structure 128 * are still unused. 129 * 130 * Check if a brand_mach_ops callback is defined for the specified callback_id 131 * type. If so invoke it with the kernel's %gs value loaded and the following 132 * data on the stack: 133 * 134 * stack: -------------------------------------- 135 * 32 | callback pointer | 136 * | 24 | user (or interrupt) stack pointer | 137 * | 16 | lwp pointer | 138 * v 8 | userland return address | 139 * 0 | callback wrapper return addr | 140 * -------------------------------------- 141 * 142 * Since we're pushing the userland return address onto the kernel stack 143 * we need to get that address without accessing the user's stack (since we 144 * can't trust that data). There are different ways to get the userland 145 * return address depending on how the syscall trap was made: 146 * 147 * a) For sys_syscall and sys_syscall32 the return address is in %rcx. 148 * b) For sys_sysenter the return address is in %rdx. 149 * c) For sys_int80 and sys_syscall_int (int91), upon entry into the macro, 150 * the stack pointer points at the state saved when we took the interrupt: 151 * ------------------------ 152 * | | user's %ss | 153 * | | user's %esp | 154 * | | EFLAGS register | 155 * v | user's %cs | 156 * | user's %eip | 157 * ------------------------ 158 * 159 * The 2nd parameter to the BRAND_CALLBACK macro is either the 160 * BRAND_URET_FROM_REG or BRAND_URET_FROM_INTR_STACK macro. These macros are 161 * used to generate the proper code to get the userland return address for 162 * each syscall entry point. 163 * 164 * The interface to the brand callbacks on the 64-bit kernel assumes %r15 165 * is available as a scratch register within the callback. If the callback 166 * returns within the kernel then this macro will restore %r15. If the 167 * callback is going to return directly to userland then it should restore 168 * %r15 before returning to userland. 169 */ 170#define BRAND_URET_FROM_REG(rip_reg) \ 171 pushq rip_reg /* push the return address */ 172 173/* 174 * The interrupt stack pointer we saved on entry to the BRAND_CALLBACK macro 175 * is currently pointing at the user return address (%eip). 176 */ 177#define BRAND_URET_FROM_INTR_STACK() \ 178 movq %gs:CPU_RTMP_RSP, %r15 /* grab the intr. stack pointer */ ;\ 179 pushq (%r15) /* push the return address */ 180 181#define BRAND_CALLBACK(callback_id, push_userland_ret) \ 182 movq %rsp, %gs:CPU_RTMP_RSP /* save the stack pointer */ ;\ 183 movq %r15, %gs:CPU_RTMP_R15 /* save %r15 */ ;\ 184 movq %gs:CPU_THREAD, %r15 /* load the thread pointer */ ;\ 185 movq T_STACK(%r15), %rsp /* switch to the kernel stack */ ;\ 186 subq $16, %rsp /* save space for 2 pointers */ ;\ 187 pushq %r14 /* save %r14 */ ;\ 188 movq %gs:CPU_RTMP_RSP, %r14 ;\ 189 movq %r14, 8(%rsp) /* stash the user stack pointer */ ;\ 190 popq %r14 /* restore %r14 */ ;\ 191 movq T_LWP(%r15), %r15 /* load the lwp pointer */ ;\ 192 pushq %r15 /* push the lwp pointer */ ;\ 193 movq LWP_PROCP(%r15), %r15 /* load the proc pointer */ ;\ 194 movq P_BRAND(%r15), %r15 /* load the brand pointer */ ;\ 195 movq B_MACHOPS(%r15), %r15 /* load the machops pointer */ ;\ 196 movq _CONST(_MUL(callback_id, CPTRSIZE))(%r15), %r15 ;\ 197 cmpq $0, %r15 ;\ 198 je 1f ;\ 199 movq %r15, 16(%rsp) /* save the callback pointer */ ;\ 200 push_userland_ret /* push the return address */ ;\ 201 call *24(%rsp) /* call callback */ ;\ 2021: movq %gs:CPU_RTMP_R15, %r15 /* restore %r15 */ ;\ 203 movq %gs:CPU_RTMP_RSP, %rsp /* restore the stack pointer */ 204 205#define MSTATE_TRANSITION(from, to) \ 206 movl $from, %edi; \ 207 movl $to, %esi; \ 208 call syscall_mstate 209 210/* 211 * Check to see if a simple (direct) return is possible i.e. 212 * 213 * if (t->t_post_sys_ast | syscalltrace | 214 * lwp->lwp_pcb.pcb_rupdate == 1) 215 * do full version ; 216 * 217 * Preconditions: 218 * - t is curthread 219 * Postconditions: 220 * - condition code NE is set if post-sys is too complex 221 * - rtmp is zeroed if it isn't (we rely on this!) 222 * - ltmp is smashed 223 */ 224#define CHECK_POSTSYS_NE(t, ltmp, rtmp) \ 225 movq T_LWP(t), ltmp; \ 226 movzbl PCB_RUPDATE(ltmp), rtmp; \ 227 ORL_SYSCALLTRACE(rtmp); \ 228 orl T_POST_SYS_AST(t), rtmp; \ 229 cmpl $0, rtmp 230 231/* 232 * Fix up the lwp, thread, and eflags for a successful return 233 * 234 * Preconditions: 235 * - zwreg contains zero 236 */ 237#define SIMPLE_SYSCALL_POSTSYS(t, lwp, zwreg) \ 238 movb $LWP_USER, LWP_STATE(lwp); \ 239 movw zwreg, T_SYSNUM(t); \ 240 andb $_CONST(0xffff - PS_C), REGOFF_RFL(%rsp) 241 242/* 243 * ASSERT(lwptoregs(lwp) == rp); 244 * 245 * This may seem obvious, but very odd things happen if this 246 * assertion is false 247 * 248 * Preconditions: 249 * (%rsp is ready for normal call sequence) 250 * Postconditions (if assertion is true): 251 * %r11 is smashed 252 * 253 * ASSERT(rp->r_cs == descnum) 254 * 255 * The code selector is written into the regs structure when the 256 * lwp stack is created. We use this ASSERT to validate that 257 * the regs structure really matches how we came in. 258 * 259 * Preconditions: 260 * (%rsp is ready for normal call sequence) 261 * Postconditions (if assertion is true): 262 * -none- 263 * 264 * ASSERT(lwp->lwp_pcb.pcb_rupdate == 0); 265 * 266 * If this is false, it meant that we returned to userland without 267 * updating the segment registers as we were supposed to. 268 * 269 * Note that we must ensure no interrupts or other traps intervene 270 * between entering privileged mode and performing the assertion, 271 * otherwise we may perform a context switch on the thread, which 272 * will end up setting pcb_rupdate to 1 again. 273 */ 274#if defined(DEBUG) 275 276#if !defined(__lint) 277 278__lwptoregs_msg: 279 .string "syscall_asm_amd64.s:%d lwptoregs(%p) [%p] != rp [%p]" 280 281__codesel_msg: 282 .string "syscall_asm_amd64.s:%d rp->r_cs [%ld] != %ld" 283 284__no_rupdate_msg: 285 .string "syscall_asm_amd64.s:%d lwp %p, pcb_rupdate != 0" 286 287#endif /* !__lint */ 288 289#define ASSERT_LWPTOREGS(lwp, rp) \ 290 movq LWP_REGS(lwp), %r11; \ 291 cmpq rp, %r11; \ 292 je 7f; \ 293 leaq __lwptoregs_msg(%rip), %rdi; \ 294 movl $__LINE__, %esi; \ 295 movq lwp, %rdx; \ 296 movq %r11, %rcx; \ 297 movq rp, %r8; \ 298 xorl %eax, %eax; \ 299 call panic; \ 3007: 301 302#define ASSERT_NO_RUPDATE_PENDING(lwp) \ 303 testb $0x1, PCB_RUPDATE(lwp); \ 304 je 8f; \ 305 movq lwp, %rdx; \ 306 leaq __no_rupdate_msg(%rip), %rdi; \ 307 movl $__LINE__, %esi; \ 308 xorl %eax, %eax; \ 309 call panic; \ 3108: 311 312#else 313#define ASSERT_LWPTOREGS(lwp, rp) 314#define ASSERT_NO_RUPDATE_PENDING(lwp) 315#endif 316 317/* 318 * Do the traptrace thing and restore any registers we used 319 * in situ. Assumes that %rsp is pointing at the base of 320 * the struct regs, obviously .. 321 */ 322#ifdef TRAPTRACE 323#define SYSCALL_TRAPTRACE(ttype) \ 324 TRACE_PTR(%rdi, %rbx, %ebx, %rcx, ttype); \ 325 TRACE_REGS(%rdi, %rsp, %rbx, %rcx); \ 326 TRACE_STAMP(%rdi); /* rdtsc clobbers %eax, %edx */ \ 327 movq REGOFF_RAX(%rsp), %rax; \ 328 movq REGOFF_RBX(%rsp), %rbx; \ 329 movq REGOFF_RCX(%rsp), %rcx; \ 330 movq REGOFF_RDX(%rsp), %rdx; \ 331 movl %eax, TTR_SYSNUM(%rdi); \ 332 movq REGOFF_RDI(%rsp), %rdi 333 334#define SYSCALL_TRAPTRACE32(ttype) \ 335 SYSCALL_TRAPTRACE(ttype); \ 336 /* paranoia: clean the top 32-bits of the registers */ \ 337 orl %eax, %eax; \ 338 orl %ebx, %ebx; \ 339 orl %ecx, %ecx; \ 340 orl %edx, %edx; \ 341 orl %edi, %edi 342#else /* TRAPTRACE */ 343#define SYSCALL_TRAPTRACE(ttype) 344#define SYSCALL_TRAPTRACE32(ttype) 345#endif /* TRAPTRACE */ 346 347/* 348 * The 64-bit libc syscall wrapper does this: 349 * 350 * fn(<args>) 351 * { 352 * movq %rcx, %r10 -- because syscall smashes %rcx 353 * movl $CODE, %eax 354 * syscall 355 * <error processing> 356 * } 357 * 358 * Thus when we come into the kernel: 359 * 360 * %rdi, %rsi, %rdx, %r10, %r8, %r9 contain first six args 361 * %rax is the syscall number 362 * %r12-%r15 contain caller state 363 * 364 * The syscall instruction arranges that: 365 * 366 * %rcx contains the return %rip 367 * %r11d contains bottom 32-bits of %rflags 368 * %rflags is masked (as determined by the SFMASK msr) 369 * %cs is set to UCS_SEL (as determined by the STAR msr) 370 * %ss is set to UDS_SEL (as determined by the STAR msr) 371 * %rip is set to sys_syscall (as determined by the LSTAR msr) 372 * 373 * Or in other words, we have no registers available at all. 374 * Only swapgs can save us! 375 * 376 * Under the hypervisor, the swapgs has happened already. However, the 377 * state of the world is very different from that we're familiar with. 378 * 379 * In particular, we have a stack structure like that for interrupt 380 * gates, except that the %cs and %ss registers are modified for reasons 381 * that are not entirely clear. Critically, the %rcx/%r11 values do 382 * *not* reflect the usage of those registers under a 'real' syscall[1]; 383 * the stack, therefore, looks like this: 384 * 385 * 0x0(rsp) potentially junk %rcx 386 * 0x8(rsp) potentially junk %r11 387 * 0x10(rsp) user %rip 388 * 0x18(rsp) modified %cs 389 * 0x20(rsp) user %rflags 390 * 0x28(rsp) user %rsp 391 * 0x30(rsp) modified %ss 392 * 393 * 394 * and before continuing on, we must load the %rip into %rcx and the 395 * %rflags into %r11. 396 * 397 * [1] They used to, and we relied on it, but this was broken in 3.1.1. 398 * Sigh. 399 */ 400#if defined(__xpv) 401#define XPV_SYSCALL_PROD \ 402 movq 0x10(%rsp), %rcx; \ 403 movq 0x20(%rsp), %r11; \ 404 movq 0x28(%rsp), %rsp 405#else 406#define XPV_SYSCALL_PROD /* nothing */ 407#endif 408 409#if defined(__lint) 410 411/*ARGSUSED*/ 412void 413sys_syscall() 414{} 415 416void 417_allsyscalls() 418{} 419 420size_t _allsyscalls_size; 421 422#else /* __lint */ 423 424 ENTRY_NP2(brand_sys_syscall,_allsyscalls) 425 SWAPGS /* kernel gsbase */ 426 XPV_SYSCALL_PROD 427 BRAND_CALLBACK(BRAND_CB_SYSCALL, BRAND_URET_FROM_REG(%rcx)) 428 jmp noprod_sys_syscall 429 430 ALTENTRY(sys_syscall) 431 SWAPGS /* kernel gsbase */ 432 XPV_SYSCALL_PROD 433 434noprod_sys_syscall: 435 movq %r15, %gs:CPU_RTMP_R15 436 movq %rsp, %gs:CPU_RTMP_RSP 437 438 movq %gs:CPU_THREAD, %r15 439 movq T_STACK(%r15), %rsp /* switch from user to kernel stack */ 440 441 ASSERT_UPCALL_MASK_IS_SET 442 443 movl $UCS_SEL, REGOFF_CS(%rsp) 444 movq %rcx, REGOFF_RIP(%rsp) /* syscall: %rip -> %rcx */ 445 movq %r11, REGOFF_RFL(%rsp) /* syscall: %rfl -> %r11d */ 446 movl $UDS_SEL, REGOFF_SS(%rsp) 447 448 movl %eax, %eax /* wrapper: sysc# -> %eax */ 449 movq %rdi, REGOFF_RDI(%rsp) 450 movq %rsi, REGOFF_RSI(%rsp) 451 movq %rdx, REGOFF_RDX(%rsp) 452 movq %r10, REGOFF_RCX(%rsp) /* wrapper: %rcx -> %r10 */ 453 movq %r10, %rcx /* arg[3] for direct calls */ 454 455 movq %r8, REGOFF_R8(%rsp) 456 movq %r9, REGOFF_R9(%rsp) 457 movq %rax, REGOFF_RAX(%rsp) 458 movq %rbx, REGOFF_RBX(%rsp) 459 460 movq %rbp, REGOFF_RBP(%rsp) 461 movq %r10, REGOFF_R10(%rsp) 462 movq %gs:CPU_RTMP_RSP, %r11 463 movq %r11, REGOFF_RSP(%rsp) 464 movq %r12, REGOFF_R12(%rsp) 465 466 movq %r13, REGOFF_R13(%rsp) 467 movq %r14, REGOFF_R14(%rsp) 468 movq %gs:CPU_RTMP_R15, %r10 469 movq %r10, REGOFF_R15(%rsp) 470 movq $0, REGOFF_SAVFP(%rsp) 471 movq $0, REGOFF_SAVPC(%rsp) 472 473 /* 474 * Copy these registers here in case we end up stopped with 475 * someone (like, say, /proc) messing with our register state. 476 * We don't -restore- them unless we have to in update_sregs. 477 * 478 * Since userland -can't- change fsbase or gsbase directly, 479 * and capturing them involves two serializing instructions, 480 * we don't bother to capture them here. 481 */ 482 xorl %ebx, %ebx 483 movw %ds, %bx 484 movq %rbx, REGOFF_DS(%rsp) 485 movw %es, %bx 486 movq %rbx, REGOFF_ES(%rsp) 487 movw %fs, %bx 488 movq %rbx, REGOFF_FS(%rsp) 489 movw %gs, %bx 490 movq %rbx, REGOFF_GS(%rsp) 491 492 /* 493 * Machine state saved in the regs structure on the stack 494 * First six args in %rdi, %rsi, %rdx, %rcx, %r8, %r9 495 * %eax is the syscall number 496 * %rsp is the thread's stack, %r15 is curthread 497 * REG_RSP(%rsp) is the user's stack 498 */ 499 500 SYSCALL_TRAPTRACE($TT_SYSC64) 501 502 movq %rsp, %rbp 503 504 movq T_LWP(%r15), %r14 505 ASSERT_NO_RUPDATE_PENDING(%r14) 506 ENABLE_INTR_FLAGS 507 508 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 509 movl REGOFF_RAX(%rsp), %eax /* (%rax damaged by mstate call) */ 510 511 ASSERT_LWPTOREGS(%r14, %rsp) 512 513 movb $LWP_SYS, LWP_STATE(%r14) 514 incq LWP_RU_SYSC(%r14) 515 movb $NORMALRETURN, LWP_EOSYS(%r14) 516 517 incq %gs:CPU_STATS_SYS_SYSCALL 518 519 movw %ax, T_SYSNUM(%r15) 520 movzbl T_PRE_SYS(%r15), %ebx 521 ORL_SYSCALLTRACE(%ebx) 522 testl %ebx, %ebx 523 jne _syscall_pre 524 525_syscall_invoke: 526 movq REGOFF_RDI(%rbp), %rdi 527 movq REGOFF_RSI(%rbp), %rsi 528 movq REGOFF_RDX(%rbp), %rdx 529 movq REGOFF_RCX(%rbp), %rcx 530 movq REGOFF_R8(%rbp), %r8 531 movq REGOFF_R9(%rbp), %r9 532 533 cmpl $NSYSCALL, %eax 534 jae _syscall_ill 535 shll $SYSENT_SIZE_SHIFT, %eax 536 leaq sysent(%rax), %rbx 537 538 call *SY_CALLC(%rbx) 539 540 movq %rax, %r12 541 movq %rdx, %r13 542 543 /* 544 * If the handler returns two ints, then we need to split the 545 * 64-bit return value into two 32-bit values. 546 */ 547 testw $SE_32RVAL2, SY_FLAGS(%rbx) 548 je 5f 549 movq %r12, %r13 550 shrq $32, %r13 /* upper 32-bits into %edx */ 551 movl %r12d, %r12d /* lower 32-bits into %eax */ 5525: 553 /* 554 * Optimistically assume that there's no post-syscall 555 * work to do. (This is to avoid having to call syscall_mstate() 556 * with interrupts disabled) 557 */ 558 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 559 560 /* 561 * We must protect ourselves from being descheduled here; 562 * If we were, and we ended up on another cpu, or another 563 * lwp got in ahead of us, it could change the segment 564 * registers without us noticing before we return to userland. 565 */ 566 CLI(%r14) 567 CHECK_POSTSYS_NE(%r15, %r14, %ebx) 568 jne _syscall_post 569 SIMPLE_SYSCALL_POSTSYS(%r15, %r14, %bx) 570 571 movq %r12, REGOFF_RAX(%rsp) 572 movq %r13, REGOFF_RDX(%rsp) 573 574 /* 575 * To get back to userland, we need the return %rip in %rcx and 576 * the return %rfl in %r11d. The sysretq instruction also arranges 577 * to fix up %cs and %ss; everything else is our responsibility. 578 */ 579 movq REGOFF_RDI(%rsp), %rdi 580 movq REGOFF_RSI(%rsp), %rsi 581 movq REGOFF_RDX(%rsp), %rdx 582 /* %rcx used to restore %rip value */ 583 584 movq REGOFF_R8(%rsp), %r8 585 movq REGOFF_R9(%rsp), %r9 586 movq REGOFF_RAX(%rsp), %rax 587 movq REGOFF_RBX(%rsp), %rbx 588 589 movq REGOFF_RBP(%rsp), %rbp 590 movq REGOFF_R10(%rsp), %r10 591 /* %r11 used to restore %rfl value */ 592 movq REGOFF_R12(%rsp), %r12 593 594 movq REGOFF_R13(%rsp), %r13 595 movq REGOFF_R14(%rsp), %r14 596 movq REGOFF_R15(%rsp), %r15 597 598 movq REGOFF_RIP(%rsp), %rcx 599 movl REGOFF_RFL(%rsp), %r11d 600 601#if defined(__xpv) 602 addq $REGOFF_RIP, %rsp 603#else 604 movq REGOFF_RSP(%rsp), %rsp 605#endif 606 607 /* 608 * There can be no instructions between the ALTENTRY below and 609 * SYSRET or we could end up breaking brand support. See label usage 610 * in sn1_brand_syscall_callback for an example. 611 */ 612 ASSERT_UPCALL_MASK_IS_SET 613#if defined(__xpv) 614 SYSRETQ 615 ALTENTRY(nopop_sys_syscall_swapgs_sysretq) 616 617 /* 618 * We can only get here after executing a brand syscall 619 * interposition callback handler and simply need to 620 * "sysretq" back to userland. On the hypervisor this 621 * involves the iret hypercall which requires us to construct 622 * just enough of the stack needed for the hypercall. 623 * (rip, cs, rflags, rsp, ss). 624 */ 625 movq %rsp, %gs:CPU_RTMP_RSP /* save user's rsp */ 626 movq %gs:CPU_THREAD, %r11 627 movq T_STACK(%r11), %rsp 628 629 movq %rcx, REGOFF_RIP(%rsp) 630 movl $UCS_SEL, REGOFF_CS(%rsp) 631 movq %gs:CPU_RTMP_RSP, %r11 632 movq %r11, REGOFF_RSP(%rsp) 633 pushfq 634 popq %r11 /* hypercall enables ints */ 635 movq %r11, REGOFF_RFL(%rsp) 636 movl $UDS_SEL, REGOFF_SS(%rsp) 637 addq $REGOFF_RIP, %rsp 638 /* 639 * XXPV: see comment in SYSRETQ definition for future optimization 640 * we could take. 641 */ 642 ASSERT_UPCALL_MASK_IS_SET 643 SYSRETQ 644#else 645 ALTENTRY(nopop_sys_syscall_swapgs_sysretq) 646 SWAPGS /* user gsbase */ 647 SYSRETQ 648#endif 649 /*NOTREACHED*/ 650 SET_SIZE(nopop_sys_syscall_swapgs_sysretq) 651 652_syscall_pre: 653 call pre_syscall 654 movl %eax, %r12d 655 testl %eax, %eax 656 jne _syscall_post_call 657 /* 658 * Didn't abort, so reload the syscall args and invoke the handler. 659 */ 660 movzwl T_SYSNUM(%r15), %eax 661 jmp _syscall_invoke 662 663_syscall_ill: 664 call nosys 665 movq %rax, %r12 666 movq %rdx, %r13 667 jmp _syscall_post_call 668 669_syscall_post: 670 STI 671 /* 672 * Sigh, our optimism wasn't justified, put it back to LMS_SYSTEM 673 * so that we can account for the extra work it takes us to finish. 674 */ 675 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 676_syscall_post_call: 677 movq %r12, %rdi 678 movq %r13, %rsi 679 call post_syscall 680 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 681 jmp _sys_rtt 682 SET_SIZE(sys_syscall) 683 SET_SIZE(brand_sys_syscall) 684 685#endif /* __lint */ 686 687#if defined(__lint) 688 689/*ARGSUSED*/ 690void 691sys_syscall32() 692{} 693 694#else /* __lint */ 695 696 ENTRY_NP(brand_sys_syscall32) 697 SWAPGS /* kernel gsbase */ 698 XPV_TRAP_POP 699 BRAND_CALLBACK(BRAND_CB_SYSCALL32, BRAND_URET_FROM_REG(%rcx)) 700 jmp nopop_sys_syscall32 701 702 ALTENTRY(sys_syscall32) 703 SWAPGS /* kernel gsbase */ 704 XPV_TRAP_POP 705 706nopop_sys_syscall32: 707 movl %esp, %r10d 708 movq %gs:CPU_THREAD, %r15 709 movq T_STACK(%r15), %rsp 710 movl %eax, %eax 711 712 movl $U32CS_SEL, REGOFF_CS(%rsp) 713 movl %ecx, REGOFF_RIP(%rsp) /* syscall: %rip -> %rcx */ 714 movq %r11, REGOFF_RFL(%rsp) /* syscall: %rfl -> %r11d */ 715 movq %r10, REGOFF_RSP(%rsp) 716 movl $UDS_SEL, REGOFF_SS(%rsp) 717 718_syscall32_save: 719 movl %edi, REGOFF_RDI(%rsp) 720 movl %esi, REGOFF_RSI(%rsp) 721 movl %ebp, REGOFF_RBP(%rsp) 722 movl %ebx, REGOFF_RBX(%rsp) 723 movl %edx, REGOFF_RDX(%rsp) 724 movl %ecx, REGOFF_RCX(%rsp) 725 movl %eax, REGOFF_RAX(%rsp) /* wrapper: sysc# -> %eax */ 726 movq $0, REGOFF_SAVFP(%rsp) 727 movq $0, REGOFF_SAVPC(%rsp) 728 729 /* 730 * Copy these registers here in case we end up stopped with 731 * someone (like, say, /proc) messing with our register state. 732 * We don't -restore- them unless we have to in update_sregs. 733 * 734 * Since userland -can't- change fsbase or gsbase directly, 735 * we don't bother to capture them here. 736 */ 737 xorl %ebx, %ebx 738 movw %ds, %bx 739 movq %rbx, REGOFF_DS(%rsp) 740 movw %es, %bx 741 movq %rbx, REGOFF_ES(%rsp) 742 movw %fs, %bx 743 movq %rbx, REGOFF_FS(%rsp) 744 movw %gs, %bx 745 movq %rbx, REGOFF_GS(%rsp) 746 747 /* 748 * Application state saved in the regs structure on the stack 749 * %eax is the syscall number 750 * %rsp is the thread's stack, %r15 is curthread 751 * REG_RSP(%rsp) is the user's stack 752 */ 753 754 SYSCALL_TRAPTRACE32($TT_SYSC) 755 756 movq %rsp, %rbp 757 758 movq T_LWP(%r15), %r14 759 ASSERT_NO_RUPDATE_PENDING(%r14) 760 761 ENABLE_INTR_FLAGS 762 763 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 764 movl REGOFF_RAX(%rsp), %eax /* (%rax damaged by mstate call) */ 765 766 ASSERT_LWPTOREGS(%r14, %rsp) 767 768 incq %gs:CPU_STATS_SYS_SYSCALL 769 770 /* 771 * Make some space for MAXSYSARGS (currently 8) 32-bit args placed 772 * into 64-bit (long) arg slots, maintaining 16 byte alignment. Or 773 * more succinctly: 774 * 775 * SA(MAXSYSARGS * sizeof (long)) == 64 776 */ 777#define SYS_DROP 64 /* drop for args */ 778 subq $SYS_DROP, %rsp 779 movb $LWP_SYS, LWP_STATE(%r14) 780 movq %r15, %rdi 781 movq %rsp, %rsi 782 call syscall_entry 783 784 /* 785 * Fetch the arguments copied onto the kernel stack and put 786 * them in the right registers to invoke a C-style syscall handler. 787 * %rax contains the handler address. 788 * 789 * Ideas for making all this go faster of course include simply 790 * forcibly fetching 6 arguments from the user stack under lofault 791 * protection, reverting to copyin_args only when watchpoints 792 * are in effect. 793 * 794 * (If we do this, make sure that exec and libthread leave 795 * enough space at the top of the stack to ensure that we'll 796 * never do a fetch from an invalid page.) 797 * 798 * Lots of ideas here, but they won't really help with bringup B-) 799 * Correctness can't wait, performance can wait a little longer .. 800 */ 801 802 movq %rax, %rbx 803 movl 0(%rsp), %edi 804 movl 8(%rsp), %esi 805 movl 0x10(%rsp), %edx 806 movl 0x18(%rsp), %ecx 807 movl 0x20(%rsp), %r8d 808 movl 0x28(%rsp), %r9d 809 810 call *SY_CALLC(%rbx) 811 812 movq %rbp, %rsp /* pop the args */ 813 814 /* 815 * amd64 syscall handlers -always- return a 64-bit value in %rax. 816 * On the 32-bit kernel, they always return that value in %eax:%edx 817 * as required by the 32-bit ABI. 818 * 819 * Simulate the same behaviour by unconditionally splitting the 820 * return value in the same way. 821 */ 822 movq %rax, %r13 823 shrq $32, %r13 /* upper 32-bits into %edx */ 824 movl %eax, %r12d /* lower 32-bits into %eax */ 825 826 /* 827 * Optimistically assume that there's no post-syscall 828 * work to do. (This is to avoid having to call syscall_mstate() 829 * with interrupts disabled) 830 */ 831 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 832 833 /* 834 * We must protect ourselves from being descheduled here; 835 * If we were, and we ended up on another cpu, or another 836 * lwp got in ahead of us, it could change the segment 837 * registers without us noticing before we return to userland. 838 */ 839 CLI(%r14) 840 CHECK_POSTSYS_NE(%r15, %r14, %ebx) 841 jne _full_syscall_postsys32 842 SIMPLE_SYSCALL_POSTSYS(%r15, %r14, %bx) 843 844 /* 845 * To get back to userland, we need to put the return %rip in %rcx and 846 * the return %rfl in %r11d. The sysret instruction also arranges 847 * to fix up %cs and %ss; everything else is our responsibility. 848 */ 849 850 movl %r12d, %eax /* %eax: rval1 */ 851 movl REGOFF_RBX(%rsp), %ebx 852 /* %ecx used for return pointer */ 853 movl %r13d, %edx /* %edx: rval2 */ 854 movl REGOFF_RBP(%rsp), %ebp 855 movl REGOFF_RSI(%rsp), %esi 856 movl REGOFF_RDI(%rsp), %edi 857 858 movl REGOFF_RFL(%rsp), %r11d /* %r11 -> eflags */ 859 movl REGOFF_RIP(%rsp), %ecx /* %ecx -> %eip */ 860 movl REGOFF_RSP(%rsp), %esp 861 862 ASSERT_UPCALL_MASK_IS_SET 863 ALTENTRY(nopop_sys_syscall32_swapgs_sysretl) 864 SWAPGS /* user gsbase */ 865 SYSRETL 866 SET_SIZE(nopop_sys_syscall32_swapgs_sysretl) 867 /*NOTREACHED*/ 868 869_full_syscall_postsys32: 870 STI 871 /* 872 * Sigh, our optimism wasn't justified, put it back to LMS_SYSTEM 873 * so that we can account for the extra work it takes us to finish. 874 */ 875 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 876 movq %r15, %rdi 877 movq %r12, %rsi /* rval1 - %eax */ 878 movq %r13, %rdx /* rval2 - %edx */ 879 call syscall_exit 880 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 881 jmp _sys_rtt 882 SET_SIZE(sys_syscall32) 883 SET_SIZE(brand_sys_syscall32) 884 885#endif /* __lint */ 886 887/* 888 * System call handler via the sysenter instruction 889 * Used only for 32-bit system calls on the 64-bit kernel. 890 * 891 * The caller in userland has arranged that: 892 * 893 * - %eax contains the syscall number 894 * - %ecx contains the user %esp 895 * - %edx contains the return %eip 896 * - the user stack contains the args to the syscall 897 * 898 * Hardware and (privileged) initialization code have arranged that by 899 * the time the sysenter instructions completes: 900 * 901 * - %rip is pointing to sys_sysenter (below). 902 * - %cs and %ss are set to kernel text and stack (data) selectors. 903 * - %rsp is pointing at the lwp's stack 904 * - interrupts have been disabled. 905 * 906 * Note that we are unable to return both "rvals" to userland with 907 * this call, as %edx is used by the sysexit instruction. 908 * 909 * One final complication in this routine is its interaction with 910 * single-stepping in a debugger. For most of the system call mechanisms, 911 * the CPU automatically clears the single-step flag before we enter the 912 * kernel. The sysenter mechanism does not clear the flag, so a user 913 * single-stepping through a libc routine may suddenly find him/herself 914 * single-stepping through the kernel. To detect this, kmdb compares the 915 * trap %pc to the [brand_]sys_enter addresses on each single-step trap. 916 * If it finds that we have single-stepped to a sysenter entry point, it 917 * explicitly clears the flag and executes the sys_sysenter routine. 918 * 919 * One final complication in this final complication is the fact that we 920 * have two different entry points for sysenter: brand_sys_sysenter and 921 * sys_sysenter. If we enter at brand_sys_sysenter and start single-stepping 922 * through the kernel with kmdb, we will eventually hit the instruction at 923 * sys_sysenter. kmdb cannot distinguish between that valid single-step 924 * and the undesirable one mentioned above. To avoid this situation, we 925 * simply add a jump over the instruction at sys_sysenter to make it 926 * impossible to single-step to it. 927 */ 928#if defined(__lint) 929 930void 931sys_sysenter() 932{} 933 934#else /* __lint */ 935 936 ENTRY_NP(brand_sys_sysenter) 937 SWAPGS /* kernel gsbase */ 938 ALTENTRY(_brand_sys_sysenter_post_swapgs) 939 BRAND_CALLBACK(BRAND_CB_SYSENTER, BRAND_URET_FROM_REG(%rdx)) 940 /* 941 * Jump over sys_sysenter to allow single-stepping as described 942 * above. 943 */ 944 jmp _sys_sysenter_post_swapgs 945 946 ALTENTRY(sys_sysenter) 947 SWAPGS /* kernel gsbase */ 948 949 ALTENTRY(_sys_sysenter_post_swapgs) 950 movq %gs:CPU_THREAD, %r15 951 952 movl $U32CS_SEL, REGOFF_CS(%rsp) 953 movl %ecx, REGOFF_RSP(%rsp) /* wrapper: %esp -> %ecx */ 954 movl %edx, REGOFF_RIP(%rsp) /* wrapper: %eip -> %edx */ 955 pushfq 956 popq %r10 957 movl $UDS_SEL, REGOFF_SS(%rsp) 958 959 /* 960 * Set the interrupt flag before storing the flags to the 961 * flags image on the stack so we can return to user with 962 * interrupts enabled if we return via sys_rtt_syscall32 963 */ 964 orq $PS_IE, %r10 965 movq %r10, REGOFF_RFL(%rsp) 966 967 movl %edi, REGOFF_RDI(%rsp) 968 movl %esi, REGOFF_RSI(%rsp) 969 movl %ebp, REGOFF_RBP(%rsp) 970 movl %ebx, REGOFF_RBX(%rsp) 971 movl %edx, REGOFF_RDX(%rsp) 972 movl %ecx, REGOFF_RCX(%rsp) 973 movl %eax, REGOFF_RAX(%rsp) /* wrapper: sysc# -> %eax */ 974 movq $0, REGOFF_SAVFP(%rsp) 975 movq $0, REGOFF_SAVPC(%rsp) 976 977 /* 978 * Copy these registers here in case we end up stopped with 979 * someone (like, say, /proc) messing with our register state. 980 * We don't -restore- them unless we have to in update_sregs. 981 * 982 * Since userland -can't- change fsbase or gsbase directly, 983 * we don't bother to capture them here. 984 */ 985 xorl %ebx, %ebx 986 movw %ds, %bx 987 movq %rbx, REGOFF_DS(%rsp) 988 movw %es, %bx 989 movq %rbx, REGOFF_ES(%rsp) 990 movw %fs, %bx 991 movq %rbx, REGOFF_FS(%rsp) 992 movw %gs, %bx 993 movq %rbx, REGOFF_GS(%rsp) 994 995 /* 996 * Application state saved in the regs structure on the stack 997 * %eax is the syscall number 998 * %rsp is the thread's stack, %r15 is curthread 999 * REG_RSP(%rsp) is the user's stack 1000 */ 1001 1002 SYSCALL_TRAPTRACE($TT_SYSENTER) 1003 1004 movq %rsp, %rbp 1005 1006 movq T_LWP(%r15), %r14 1007 ASSERT_NO_RUPDATE_PENDING(%r14) 1008 1009 ENABLE_INTR_FLAGS 1010 1011 /* 1012 * Catch 64-bit process trying to issue sysenter instruction 1013 * on Nocona based systems. 1014 */ 1015 movq LWP_PROCP(%r14), %rax 1016 cmpq $DATAMODEL_ILP32, P_MODEL(%rax) 1017 je 7f 1018 1019 /* 1020 * For a non-32-bit process, simulate a #ud, since that's what 1021 * native hardware does. The traptrace entry (above) will 1022 * let you know what really happened. 1023 */ 1024 movq $T_ILLINST, REGOFF_TRAPNO(%rsp) 1025 movq REGOFF_CS(%rsp), %rdi 1026 movq %rdi, REGOFF_ERR(%rsp) 1027 movq %rsp, %rdi 1028 movq REGOFF_RIP(%rsp), %rsi 1029 movl %gs:CPU_ID, %edx 1030 call trap 1031 jmp _sys_rtt 10327: 1033 1034 MSTATE_TRANSITION(LMS_USER, LMS_SYSTEM) 1035 movl REGOFF_RAX(%rsp), %eax /* (%rax damaged by mstate calls) */ 1036 1037 ASSERT_LWPTOREGS(%r14, %rsp) 1038 1039 incq %gs:CPU_STATS_SYS_SYSCALL 1040 1041 /* 1042 * Make some space for MAXSYSARGS (currently 8) 32-bit args 1043 * placed into 64-bit (long) arg slots, plus one 64-bit 1044 * (long) arg count, maintaining 16 byte alignment. 1045 */ 1046 subq $SYS_DROP, %rsp 1047 movb $LWP_SYS, LWP_STATE(%r14) 1048 movq %r15, %rdi 1049 movq %rsp, %rsi 1050 call syscall_entry 1051 1052 /* 1053 * Fetch the arguments copied onto the kernel stack and put 1054 * them in the right registers to invoke a C-style syscall handler. 1055 * %rax contains the handler address. 1056 */ 1057 movq %rax, %rbx 1058 movl 0(%rsp), %edi 1059 movl 8(%rsp), %esi 1060 movl 0x10(%rsp), %edx 1061 movl 0x18(%rsp), %ecx 1062 movl 0x20(%rsp), %r8d 1063 movl 0x28(%rsp), %r9d 1064 1065 call *SY_CALLC(%rbx) 1066 1067 movq %rbp, %rsp /* pop the args */ 1068 1069 /* 1070 * amd64 syscall handlers -always- return a 64-bit value in %rax. 1071 * On the 32-bit kernel, the always return that value in %eax:%edx 1072 * as required by the 32-bit ABI. 1073 * 1074 * Simulate the same behaviour by unconditionally splitting the 1075 * return value in the same way. 1076 */ 1077 movq %rax, %r13 1078 shrq $32, %r13 /* upper 32-bits into %edx */ 1079 movl %eax, %r12d /* lower 32-bits into %eax */ 1080 1081 /* 1082 * Optimistically assume that there's no post-syscall 1083 * work to do. (This is to avoid having to call syscall_mstate() 1084 * with interrupts disabled) 1085 */ 1086 MSTATE_TRANSITION(LMS_SYSTEM, LMS_USER) 1087 1088 /* 1089 * We must protect ourselves from being descheduled here; 1090 * If we were, and we ended up on another cpu, or another 1091 * lwp got int ahead of us, it could change the segment 1092 * registers without us noticing before we return to userland. 1093 */ 1094 cli 1095 CHECK_POSTSYS_NE(%r15, %r14, %ebx) 1096 jne _full_syscall_postsys32 1097 SIMPLE_SYSCALL_POSTSYS(%r15, %r14, %bx) 1098 1099 /* 1100 * To get back to userland, load up the 32-bit registers and 1101 * sysexit back where we came from. 1102 */ 1103 1104 /* 1105 * Interrupts will be turned on by the 'sti' executed just before 1106 * sysexit. The following ensures that restoring the user's rflags 1107 * doesn't enable interrupts too soon. 1108 */ 1109 andq $_BITNOT(PS_IE), REGOFF_RFL(%rsp) 1110 1111 /* 1112 * (There's no point in loading up %edx because the sysexit 1113 * mechanism smashes it.) 1114 */ 1115 movl %r12d, %eax 1116 movl REGOFF_RBX(%rsp), %ebx 1117 movl REGOFF_RBP(%rsp), %ebp 1118 movl REGOFF_RSI(%rsp), %esi 1119 movl REGOFF_RDI(%rsp), %edi 1120 1121 movl REGOFF_RIP(%rsp), %edx /* sysexit: %edx -> %eip */ 1122 pushq REGOFF_RFL(%rsp) 1123 popfq 1124 movl REGOFF_RSP(%rsp), %ecx /* sysexit: %ecx -> %esp */ 1125 ALTENTRY(sys_sysenter_swapgs_sysexit) 1126 swapgs 1127 sti 1128 sysexit 1129 SET_SIZE(sys_sysenter_swapgs_sysexit) 1130 SET_SIZE(sys_sysenter) 1131 SET_SIZE(_sys_sysenter_post_swapgs) 1132 SET_SIZE(brand_sys_sysenter) 1133 1134#endif /* __lint */ 1135 1136#if defined(__lint) 1137/* 1138 * System call via an int80. This entry point is only used by the Linux 1139 * application environment. Unlike the other entry points, there is no 1140 * default action to take if no callback is registered for this process. 1141 */ 1142void 1143sys_int80() 1144{} 1145 1146#else /* __lint */ 1147 1148 ENTRY_NP(brand_sys_int80) 1149 SWAPGS /* kernel gsbase */ 1150 XPV_TRAP_POP 1151 BRAND_CALLBACK(BRAND_CB_INT80, BRAND_URET_FROM_INTR_STACK()) 1152 SWAPGS /* user gsbase */ 1153 jmp nopop_int80 1154 1155 ENTRY_NP(sys_int80) 1156 /* 1157 * We hit an int80, but this process isn't of a brand with an int80 1158 * handler. Bad process! Make it look as if the INT failed. 1159 * Modify %rip to point before the INT, push the expected error 1160 * code and fake a GP fault. Note on 64-bit hypervisor we need 1161 * to undo the XPV_TRAP_POP and push rcx and r11 back on the stack 1162 * because gptrap will pop them again with its own XPV_TRAP_POP. 1163 */ 1164 XPV_TRAP_POP 1165nopop_int80: 1166 subq $2, (%rsp) /* int insn 2-bytes */ 1167 pushq $_CONST(_MUL(T_INT80, GATE_DESC_SIZE) + 2) 1168#if defined(__xpv) 1169 push %r11 1170 push %rcx 1171#endif 1172 jmp gptrap / GP fault 1173 SET_SIZE(sys_int80) 1174 SET_SIZE(brand_sys_int80) 1175#endif /* __lint */ 1176 1177 1178/* 1179 * This is the destination of the "int $T_SYSCALLINT" interrupt gate, used by 1180 * the generic i386 libc to do system calls. We do a small amount of setup 1181 * before jumping into the existing sys_syscall32 path. 1182 */ 1183#if defined(__lint) 1184 1185/*ARGSUSED*/ 1186void 1187sys_syscall_int() 1188{} 1189 1190#else /* __lint */ 1191 1192 ENTRY_NP(brand_sys_syscall_int) 1193 SWAPGS /* kernel gsbase */ 1194 XPV_TRAP_POP 1195 BRAND_CALLBACK(BRAND_CB_INT91, BRAND_URET_FROM_INTR_STACK()) 1196 jmp nopop_syscall_int 1197 1198 ALTENTRY(sys_syscall_int) 1199 SWAPGS /* kernel gsbase */ 1200 XPV_TRAP_POP 1201 1202nopop_syscall_int: 1203 movq %gs:CPU_THREAD, %r15 1204 movq T_STACK(%r15), %rsp 1205 movl %eax, %eax 1206 /* 1207 * Set t_post_sys on this thread to force ourselves out via the slow 1208 * path. It might be possible at some later date to optimize this out 1209 * and use a faster return mechanism. 1210 */ 1211 movb $1, T_POST_SYS(%r15) 1212 CLEAN_CS 1213 jmp _syscall32_save 1214 /* 1215 * There should be no instructions between this label and SWAPGS/IRET 1216 * or we could end up breaking branded zone support. See the usage of 1217 * this label in lx_brand_int80_callback and sn1_brand_int91_callback 1218 * for examples. 1219 */ 1220 ALTENTRY(sys_sysint_swapgs_iret) 1221 SWAPGS /* user gsbase */ 1222 IRET 1223 /*NOTREACHED*/ 1224 SET_SIZE(sys_sysint_swapgs_iret) 1225 SET_SIZE(sys_syscall_int) 1226 SET_SIZE(brand_sys_syscall_int) 1227 1228#endif /* __lint */ 1229 1230/* 1231 * Legacy 32-bit applications and old libc implementations do lcalls; 1232 * we should never get here because the LDT entry containing the syscall 1233 * segment descriptor has the "segment present" bit cleared, which means 1234 * we end up processing those system calls in trap() via a not-present trap. 1235 * 1236 * We do it this way because a call gate unhelpfully does -nothing- to the 1237 * interrupt flag bit, so an interrupt can run us just after the lcall 1238 * completes, but just before the swapgs takes effect. Thus the INTR_PUSH and 1239 * INTR_POP paths would have to be slightly more complex to dance around 1240 * this problem, and end up depending explicitly on the first 1241 * instruction of this handler being either swapgs or cli. 1242 */ 1243 1244#if defined(__lint) 1245 1246/*ARGSUSED*/ 1247void 1248sys_lcall32() 1249{} 1250 1251#else /* __lint */ 1252 1253 ENTRY_NP(sys_lcall32) 1254 SWAPGS /* kernel gsbase */ 1255 pushq $0 1256 pushq %rbp 1257 movq %rsp, %rbp 1258 leaq __lcall_panic_str(%rip), %rdi 1259 xorl %eax, %eax 1260 call panic 1261 SET_SIZE(sys_lcall32) 1262 1263__lcall_panic_str: 1264 .string "sys_lcall32: shouldn't be here!" 1265 1266/* 1267 * Declare a uintptr_t which covers the entire pc range of syscall 1268 * handlers for the stack walkers that need this. 1269 */ 1270 .align CPTRSIZE 1271 .globl _allsyscalls_size 1272 .type _allsyscalls_size, @object 1273_allsyscalls_size: 1274 .NWORD . - _allsyscalls 1275 SET_SIZE(_allsyscalls_size) 1276 1277#endif /* __lint */ 1278 1279/* 1280 * These are the thread context handlers for lwps using sysenter/sysexit. 1281 */ 1282 1283#if defined(__lint) 1284 1285/*ARGSUSED*/ 1286void 1287sep_save(void *ksp) 1288{} 1289 1290/*ARGSUSED*/ 1291void 1292sep_restore(void *ksp) 1293{} 1294 1295#else /* __lint */ 1296 1297 /* 1298 * setting this value to zero as we switch away causes the 1299 * stack-pointer-on-sysenter to be NULL, ensuring that we 1300 * don't silently corrupt another (preempted) thread stack 1301 * when running an lwp that (somehow) didn't get sep_restore'd 1302 */ 1303 ENTRY_NP(sep_save) 1304 xorl %edx, %edx 1305 xorl %eax, %eax 1306 movl $MSR_INTC_SEP_ESP, %ecx 1307 wrmsr 1308 ret 1309 SET_SIZE(sep_save) 1310 1311 /* 1312 * Update the kernel stack pointer as we resume onto this cpu. 1313 */ 1314 ENTRY_NP(sep_restore) 1315 movq %rdi, %rdx 1316 shrq $32, %rdx 1317 movl %edi, %eax 1318 movl $MSR_INTC_SEP_ESP, %ecx 1319 wrmsr 1320 ret 1321 SET_SIZE(sep_restore) 1322 1323#endif /* __lint */ 1324