1/* 2 * Copyright (C) 1991,1992 Linus Torvalds 3 * 4 * entry_32.S contains the system-call and low-level fault and trap handling routines. 5 * 6 * Stack layout while running C code: 7 * ptrace needs to have all registers on the stack. 8 * If the order here is changed, it needs to be 9 * updated in fork.c:copy_process(), signal.c:do_signal(), 10 * ptrace.c and ptrace.h 11 * 12 * 0(%esp) - %ebx 13 * 4(%esp) - %ecx 14 * 8(%esp) - %edx 15 * C(%esp) - %esi 16 * 10(%esp) - %edi 17 * 14(%esp) - %ebp 18 * 18(%esp) - %eax 19 * 1C(%esp) - %ds 20 * 20(%esp) - %es 21 * 24(%esp) - %fs 22 * 28(%esp) - %gs saved iff !CONFIG_X86_32_LAZY_GS 23 * 2C(%esp) - orig_eax 24 * 30(%esp) - %eip 25 * 34(%esp) - %cs 26 * 38(%esp) - %eflags 27 * 3C(%esp) - %oldesp 28 * 40(%esp) - %oldss 29 */ 30 31#include <linux/linkage.h> 32#include <linux/err.h> 33#include <asm/thread_info.h> 34#include <asm/irqflags.h> 35#include <asm/errno.h> 36#include <asm/segment.h> 37#include <asm/smp.h> 38#include <asm/page_types.h> 39#include <asm/percpu.h> 40#include <asm/processor-flags.h> 41#include <asm/ftrace.h> 42#include <asm/irq_vectors.h> 43#include <asm/cpufeatures.h> 44#include <asm/alternative-asm.h> 45#include <asm/asm.h> 46#include <asm/smap.h> 47#include <asm/nospec-branch.h> 48 49 .section .entry.text, "ax" 50 51/* 52 * We use macros for low-level operations which need to be overridden 53 * for paravirtualization. The following will never clobber any registers: 54 * INTERRUPT_RETURN (aka. "iret") 55 * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax") 56 * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit"). 57 * 58 * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must 59 * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY). 60 * Allowing a register to be clobbered can shrink the paravirt replacement 61 * enough to patch inline, increasing performance. 62 */ 63 64#ifdef CONFIG_PREEMPT 65# define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF 66#else 67# define preempt_stop(clobbers) 68# define resume_kernel restore_all 69#endif 70 71.macro TRACE_IRQS_IRET 72#ifdef CONFIG_TRACE_IRQFLAGS 73 testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off? 74 jz 1f 75 TRACE_IRQS_ON 761: 77#endif 78.endm 79 80/* 81 * User gs save/restore 82 * 83 * %gs is used for userland TLS and kernel only uses it for stack 84 * canary which is required to be at %gs:20 by gcc. Read the comment 85 * at the top of stackprotector.h for more info. 86 * 87 * Local labels 98 and 99 are used. 88 */ 89#ifdef CONFIG_X86_32_LAZY_GS 90 91 /* unfortunately push/pop can't be no-op */ 92.macro PUSH_GS 93 pushl $0 94.endm 95.macro POP_GS pop=0 96 addl $(4 + \pop), %esp 97.endm 98.macro POP_GS_EX 99.endm 100 101 /* all the rest are no-op */ 102.macro PTGS_TO_GS 103.endm 104.macro PTGS_TO_GS_EX 105.endm 106.macro GS_TO_REG reg 107.endm 108.macro REG_TO_PTGS reg 109.endm 110.macro SET_KERNEL_GS reg 111.endm 112 113#else /* CONFIG_X86_32_LAZY_GS */ 114 115.macro PUSH_GS 116 pushl %gs 117.endm 118 119.macro POP_GS pop=0 12098: popl %gs 121 .if \pop <> 0 122 add $\pop, %esp 123 .endif 124.endm 125.macro POP_GS_EX 126.pushsection .fixup, "ax" 12799: movl $0, (%esp) 128 jmp 98b 129.popsection 130 _ASM_EXTABLE(98b, 99b) 131.endm 132 133.macro PTGS_TO_GS 13498: mov PT_GS(%esp), %gs 135.endm 136.macro PTGS_TO_GS_EX 137.pushsection .fixup, "ax" 13899: movl $0, PT_GS(%esp) 139 jmp 98b 140.popsection 141 _ASM_EXTABLE(98b, 99b) 142.endm 143 144.macro GS_TO_REG reg 145 movl %gs, \reg 146.endm 147.macro REG_TO_PTGS reg 148 movl \reg, PT_GS(%esp) 149.endm 150.macro SET_KERNEL_GS reg 151 movl $(__KERNEL_STACK_CANARY), \reg 152 movl \reg, %gs 153.endm 154 155#endif /* CONFIG_X86_32_LAZY_GS */ 156 157.macro SAVE_ALL pt_regs_ax=%eax 158 cld 159 PUSH_GS 160 pushl %fs 161 pushl %es 162 pushl %ds 163 pushl \pt_regs_ax 164 pushl %ebp 165 pushl %edi 166 pushl %esi 167 pushl %edx 168 pushl %ecx 169 pushl %ebx 170 movl $(__USER_DS), %edx 171 movl %edx, %ds 172 movl %edx, %es 173 movl $(__KERNEL_PERCPU), %edx 174 movl %edx, %fs 175 SET_KERNEL_GS %edx 176.endm 177 178.macro RESTORE_INT_REGS 179 popl %ebx 180 popl %ecx 181 popl %edx 182 popl %esi 183 popl %edi 184 popl %ebp 185 popl %eax 186.endm 187 188.macro RESTORE_REGS pop=0 189 RESTORE_INT_REGS 1901: popl %ds 1912: popl %es 1923: popl %fs 193 POP_GS \pop 194.pushsection .fixup, "ax" 1954: movl $0, (%esp) 196 jmp 1b 1975: movl $0, (%esp) 198 jmp 2b 1996: movl $0, (%esp) 200 jmp 3b 201.popsection 202 _ASM_EXTABLE(1b, 4b) 203 _ASM_EXTABLE(2b, 5b) 204 _ASM_EXTABLE(3b, 6b) 205 POP_GS_EX 206.endm 207 208ENTRY(ret_from_fork) 209 pushl %eax 210 call schedule_tail 211 GET_THREAD_INFO(%ebp) 212 popl %eax 213 pushl $0x0202 # Reset kernel eflags 214 popfl 215 216 /* When we fork, we trace the syscall return in the child, too. */ 217 movl %esp, %eax 218 call syscall_return_slowpath 219 jmp restore_all 220END(ret_from_fork) 221 222ENTRY(ret_from_kernel_thread) 223 pushl %eax 224 call schedule_tail 225 GET_THREAD_INFO(%ebp) 226 popl %eax 227 pushl $0x0202 # Reset kernel eflags 228 popfl 229 movl PT_EBP(%esp), %eax 230 movl PT_EBX(%esp), %edx 231 CALL_NOSPEC %edx 232 movl $0, PT_EAX(%esp) 233 234 /* 235 * Kernel threads return to userspace as if returning from a syscall. 236 * We should check whether anything actually uses this path and, if so, 237 * consider switching it over to ret_from_fork. 238 */ 239 movl %esp, %eax 240 call syscall_return_slowpath 241 jmp restore_all 242ENDPROC(ret_from_kernel_thread) 243 244/* 245 * Return to user mode is not as complex as all this looks, 246 * but we want the default path for a system call return to 247 * go as quickly as possible which is why some of this is 248 * less clear than it otherwise should be. 249 */ 250 251 # userspace resumption stub bypassing syscall exit tracing 252 ALIGN 253ret_from_exception: 254 preempt_stop(CLBR_ANY) 255ret_from_intr: 256 GET_THREAD_INFO(%ebp) 257#ifdef CONFIG_VM86 258 movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS 259 movb PT_CS(%esp), %al 260 andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax 261#else 262 /* 263 * We can be coming here from child spawned by kernel_thread(). 264 */ 265 movl PT_CS(%esp), %eax 266 andl $SEGMENT_RPL_MASK, %eax 267#endif 268 cmpl $USER_RPL, %eax 269 jb resume_kernel # not returning to v8086 or userspace 270 271ENTRY(resume_userspace) 272 DISABLE_INTERRUPTS(CLBR_ANY) 273 TRACE_IRQS_OFF 274 movl %esp, %eax 275 call prepare_exit_to_usermode 276 jmp restore_all 277END(ret_from_exception) 278 279#ifdef CONFIG_PREEMPT 280ENTRY(resume_kernel) 281 DISABLE_INTERRUPTS(CLBR_ANY) 282need_resched: 283 cmpl $0, PER_CPU_VAR(__preempt_count) 284 jnz restore_all 285 testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ? 286 jz restore_all 287 call preempt_schedule_irq 288 jmp need_resched 289END(resume_kernel) 290#endif 291 292 # SYSENTER call handler stub 293ENTRY(entry_SYSENTER_32) 294 movl TSS_sysenter_sp0(%esp), %esp 295sysenter_past_esp: 296 pushl $__USER_DS /* pt_regs->ss */ 297 pushl %ebp /* pt_regs->sp (stashed in bp) */ 298 pushfl /* pt_regs->flags (except IF = 0) */ 299 orl $X86_EFLAGS_IF, (%esp) /* Fix IF */ 300 pushl $__USER_CS /* pt_regs->cs */ 301 pushl $0 /* pt_regs->ip = 0 (placeholder) */ 302 pushl %eax /* pt_regs->orig_ax */ 303 SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ 304 305 /* 306 * User mode is traced as though IRQs are on, and SYSENTER 307 * turned them off. 308 */ 309 TRACE_IRQS_OFF 310 311 movl %esp, %eax 312 call do_fast_syscall_32 313 /* XEN PV guests always use IRET path */ 314 ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \ 315 "jmp .Lsyscall_32_done", X86_FEATURE_XENPV 316 317/* Opportunistic SYSEXIT */ 318 TRACE_IRQS_ON /* User mode traces as IRQs on. */ 319 movl PT_EIP(%esp), %edx /* pt_regs->ip */ 320 movl PT_OLDESP(%esp), %ecx /* pt_regs->sp */ 3211: mov PT_FS(%esp), %fs 322 PTGS_TO_GS 323 popl %ebx /* pt_regs->bx */ 324 addl $2*4, %esp /* skip pt_regs->cx and pt_regs->dx */ 325 popl %esi /* pt_regs->si */ 326 popl %edi /* pt_regs->di */ 327 popl %ebp /* pt_regs->bp */ 328 popl %eax /* pt_regs->ax */ 329 330 /* 331 * Return back to the vDSO, which will pop ecx and edx. 332 * Don't bother with DS and ES (they already contain __USER_DS). 333 */ 334 sti 335 sysexit 336 337.pushsection .fixup, "ax" 3382: movl $0, PT_FS(%esp) 339 jmp 1b 340.popsection 341 _ASM_EXTABLE(1b, 2b) 342 PTGS_TO_GS_EX 343ENDPROC(entry_SYSENTER_32) 344 345 # system call handler stub 346ENTRY(entry_INT80_32) 347 ASM_CLAC 348 pushl %eax /* pt_regs->orig_ax */ 349 SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ 350 351 /* 352 * User mode is traced as though IRQs are on. Unlike the 64-bit 353 * case, INT80 is a trap gate on 32-bit kernels, so interrupts 354 * are already on (unless user code is messing around with iopl). 355 */ 356 357 movl %esp, %eax 358 call do_syscall_32_irqs_on 359.Lsyscall_32_done: 360 361restore_all: 362 TRACE_IRQS_IRET 363restore_all_notrace: 364#ifdef CONFIG_X86_ESPFIX32 365 movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS 366 /* 367 * Warning: PT_OLDSS(%esp) contains the wrong/random values if we 368 * are returning to the kernel. 369 * See comments in process.c:copy_thread() for details. 370 */ 371 movb PT_OLDSS(%esp), %ah 372 movb PT_CS(%esp), %al 373 andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax 374 cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax 375 je ldt_ss # returning to user-space with LDT SS 376#endif 377restore_nocheck: 378 RESTORE_REGS 4 # skip orig_eax/error_code 379irq_return: 380 INTERRUPT_RETURN 381.section .fixup, "ax" 382ENTRY(iret_exc ) 383 pushl $0 # no error code 384 pushl $do_iret_error 385 jmp error_code 386.previous 387 _ASM_EXTABLE(irq_return, iret_exc) 388 389#ifdef CONFIG_X86_ESPFIX32 390ldt_ss: 391#ifdef CONFIG_PARAVIRT 392 /* 393 * The kernel can't run on a non-flat stack if paravirt mode 394 * is active. Rather than try to fixup the high bits of 395 * ESP, bypass this code entirely. This may break DOSemu 396 * and/or Wine support in a paravirt VM, although the option 397 * is still available to implement the setting of the high 398 * 16-bits in the INTERRUPT_RETURN paravirt-op. 399 */ 400 cmpl $0, pv_info+PARAVIRT_enabled 401 jne restore_nocheck 402#endif 403 404/* 405 * Setup and switch to ESPFIX stack 406 * 407 * We're returning to userspace with a 16 bit stack. The CPU will not 408 * restore the high word of ESP for us on executing iret... This is an 409 * "official" bug of all the x86-compatible CPUs, which we can work 410 * around to make dosemu and wine happy. We do this by preloading the 411 * high word of ESP with the high word of the userspace ESP while 412 * compensating for the offset by changing to the ESPFIX segment with 413 * a base address that matches for the difference. 414 */ 415#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8) 416 mov %esp, %edx /* load kernel esp */ 417 mov PT_OLDESP(%esp), %eax /* load userspace esp */ 418 mov %dx, %ax /* eax: new kernel esp */ 419 sub %eax, %edx /* offset (low word is 0) */ 420 shr $16, %edx 421 mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */ 422 mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */ 423 pushl $__ESPFIX_SS 424 pushl %eax /* new kernel esp */ 425 /* 426 * Disable interrupts, but do not irqtrace this section: we 427 * will soon execute iret and the tracer was already set to 428 * the irqstate after the IRET: 429 */ 430 DISABLE_INTERRUPTS(CLBR_EAX) 431 lss (%esp), %esp /* switch to espfix segment */ 432 jmp restore_nocheck 433#endif 434ENDPROC(entry_INT80_32) 435 436.macro FIXUP_ESPFIX_STACK 437/* 438 * Switch back for ESPFIX stack to the normal zerobased stack 439 * 440 * We can't call C functions using the ESPFIX stack. This code reads 441 * the high word of the segment base from the GDT and swiches to the 442 * normal stack and adjusts ESP with the matching offset. 443 */ 444#ifdef CONFIG_X86_ESPFIX32 445 /* fixup the stack */ 446 mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */ 447 mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */ 448 shl $16, %eax 449 addl %esp, %eax /* the adjusted stack pointer */ 450 pushl $__KERNEL_DS 451 pushl %eax 452 lss (%esp), %esp /* switch to the normal stack segment */ 453#endif 454.endm 455.macro UNWIND_ESPFIX_STACK 456#ifdef CONFIG_X86_ESPFIX32 457 movl %ss, %eax 458 /* see if on espfix stack */ 459 cmpw $__ESPFIX_SS, %ax 460 jne 27f 461 movl $__KERNEL_DS, %eax 462 movl %eax, %ds 463 movl %eax, %es 464 /* switch to normal stack */ 465 FIXUP_ESPFIX_STACK 46627: 467#endif 468.endm 469 470/* 471 * Build the entry stubs with some assembler magic. 472 * We pack 1 stub into every 8-byte block. 473 */ 474 .align 8 475ENTRY(irq_entries_start) 476 vector=FIRST_EXTERNAL_VECTOR 477 .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR) 478 pushl $(~vector+0x80) /* Note: always in signed byte range */ 479 vector=vector+1 480 jmp common_interrupt 481 .align 8 482 .endr 483END(irq_entries_start) 484 485/* 486 * the CPU automatically disables interrupts when executing an IRQ vector, 487 * so IRQ-flags tracing has to follow that: 488 */ 489 .p2align CONFIG_X86_L1_CACHE_SHIFT 490common_interrupt: 491 ASM_CLAC 492 addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */ 493 SAVE_ALL 494 TRACE_IRQS_OFF 495 movl %esp, %eax 496 call do_IRQ 497 jmp ret_from_intr 498ENDPROC(common_interrupt) 499 500#define BUILD_INTERRUPT3(name, nr, fn) \ 501ENTRY(name) \ 502 ASM_CLAC; \ 503 pushl $~(nr); \ 504 SAVE_ALL; \ 505 TRACE_IRQS_OFF \ 506 movl %esp, %eax; \ 507 call fn; \ 508 jmp ret_from_intr; \ 509ENDPROC(name) 510 511 512#ifdef CONFIG_TRACING 513# define TRACE_BUILD_INTERRUPT(name, nr) BUILD_INTERRUPT3(trace_##name, nr, smp_trace_##name) 514#else 515# define TRACE_BUILD_INTERRUPT(name, nr) 516#endif 517 518#define BUILD_INTERRUPT(name, nr) \ 519 BUILD_INTERRUPT3(name, nr, smp_##name); \ 520 TRACE_BUILD_INTERRUPT(name, nr) 521 522/* The include is where all of the SMP etc. interrupts come from */ 523#include <asm/entry_arch.h> 524 525ENTRY(coprocessor_error) 526 ASM_CLAC 527 pushl $0 528 pushl $do_coprocessor_error 529 jmp error_code 530END(coprocessor_error) 531 532ENTRY(simd_coprocessor_error) 533 ASM_CLAC 534 pushl $0 535#ifdef CONFIG_X86_INVD_BUG 536 /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */ 537 ALTERNATIVE "pushl $do_general_protection", \ 538 "pushl $do_simd_coprocessor_error", \ 539 X86_FEATURE_XMM 540#else 541 pushl $do_simd_coprocessor_error 542#endif 543 jmp error_code 544END(simd_coprocessor_error) 545 546ENTRY(device_not_available) 547 ASM_CLAC 548 pushl $-1 # mark this as an int 549 pushl $do_device_not_available 550 jmp error_code 551END(device_not_available) 552 553#ifdef CONFIG_PARAVIRT 554ENTRY(native_iret) 555 iret 556 _ASM_EXTABLE(native_iret, iret_exc) 557END(native_iret) 558#endif 559 560ENTRY(overflow) 561 ASM_CLAC 562 pushl $0 563 pushl $do_overflow 564 jmp error_code 565END(overflow) 566 567ENTRY(bounds) 568 ASM_CLAC 569 pushl $0 570 pushl $do_bounds 571 jmp error_code 572END(bounds) 573 574ENTRY(invalid_op) 575 ASM_CLAC 576 pushl $0 577 pushl $do_invalid_op 578 jmp error_code 579END(invalid_op) 580 581ENTRY(coprocessor_segment_overrun) 582 ASM_CLAC 583 pushl $0 584 pushl $do_coprocessor_segment_overrun 585 jmp error_code 586END(coprocessor_segment_overrun) 587 588ENTRY(invalid_TSS) 589 ASM_CLAC 590 pushl $do_invalid_TSS 591 jmp error_code 592END(invalid_TSS) 593 594ENTRY(segment_not_present) 595 ASM_CLAC 596 pushl $do_segment_not_present 597 jmp error_code 598END(segment_not_present) 599 600ENTRY(stack_segment) 601 ASM_CLAC 602 pushl $do_stack_segment 603 jmp error_code 604END(stack_segment) 605 606ENTRY(alignment_check) 607 ASM_CLAC 608 pushl $do_alignment_check 609 jmp error_code 610END(alignment_check) 611 612ENTRY(divide_error) 613 ASM_CLAC 614 pushl $0 # no error code 615 pushl $do_divide_error 616 jmp error_code 617END(divide_error) 618 619#ifdef CONFIG_X86_MCE 620ENTRY(machine_check) 621 ASM_CLAC 622 pushl $0 623 pushl machine_check_vector 624 jmp error_code 625END(machine_check) 626#endif 627 628ENTRY(spurious_interrupt_bug) 629 ASM_CLAC 630 pushl $0 631 pushl $do_spurious_interrupt_bug 632 jmp error_code 633END(spurious_interrupt_bug) 634 635#ifdef CONFIG_XEN 636/* 637 * Xen doesn't set %esp to be precisely what the normal SYSENTER 638 * entry point expects, so fix it up before using the normal path. 639 */ 640ENTRY(xen_sysenter_target) 641 addl $5*4, %esp /* remove xen-provided frame */ 642 jmp sysenter_past_esp 643 644ENTRY(xen_hypervisor_callback) 645 pushl $-1 /* orig_ax = -1 => not a system call */ 646 SAVE_ALL 647 TRACE_IRQS_OFF 648 649 /* 650 * Check to see if we got the event in the critical 651 * region in xen_iret_direct, after we've reenabled 652 * events and checked for pending events. This simulates 653 * iret instruction's behaviour where it delivers a 654 * pending interrupt when enabling interrupts: 655 */ 656 movl PT_EIP(%esp), %eax 657 cmpl $xen_iret_start_crit, %eax 658 jb 1f 659 cmpl $xen_iret_end_crit, %eax 660 jae 1f 661 662 jmp xen_iret_crit_fixup 663 664ENTRY(xen_do_upcall) 6651: mov %esp, %eax 666 call xen_evtchn_do_upcall 667#ifndef CONFIG_PREEMPT 668 call xen_maybe_preempt_hcall 669#endif 670 jmp ret_from_intr 671ENDPROC(xen_hypervisor_callback) 672 673/* 674 * Hypervisor uses this for application faults while it executes. 675 * We get here for two reasons: 676 * 1. Fault while reloading DS, ES, FS or GS 677 * 2. Fault while executing IRET 678 * Category 1 we fix up by reattempting the load, and zeroing the segment 679 * register if the load fails. 680 * Category 2 we fix up by jumping to do_iret_error. We cannot use the 681 * normal Linux return path in this case because if we use the IRET hypercall 682 * to pop the stack frame we end up in an infinite loop of failsafe callbacks. 683 * We distinguish between categories by maintaining a status value in EAX. 684 */ 685ENTRY(xen_failsafe_callback) 686 pushl %eax 687 movl $1, %eax 6881: mov 4(%esp), %ds 6892: mov 8(%esp), %es 6903: mov 12(%esp), %fs 6914: mov 16(%esp), %gs 692 /* EAX == 0 => Category 1 (Bad segment) 693 EAX != 0 => Category 2 (Bad IRET) */ 694 testl %eax, %eax 695 popl %eax 696 lea 16(%esp), %esp 697 jz 5f 698 jmp iret_exc 6995: pushl $-1 /* orig_ax = -1 => not a system call */ 700 SAVE_ALL 701 jmp ret_from_exception 702 703.section .fixup, "ax" 7046: xorl %eax, %eax 705 movl %eax, 4(%esp) 706 jmp 1b 7077: xorl %eax, %eax 708 movl %eax, 8(%esp) 709 jmp 2b 7108: xorl %eax, %eax 711 movl %eax, 12(%esp) 712 jmp 3b 7139: xorl %eax, %eax 714 movl %eax, 16(%esp) 715 jmp 4b 716.previous 717 _ASM_EXTABLE(1b, 6b) 718 _ASM_EXTABLE(2b, 7b) 719 _ASM_EXTABLE(3b, 8b) 720 _ASM_EXTABLE(4b, 9b) 721ENDPROC(xen_failsafe_callback) 722 723BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR, 724 xen_evtchn_do_upcall) 725 726#endif /* CONFIG_XEN */ 727 728#if IS_ENABLED(CONFIG_HYPERV) 729 730BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR, 731 hyperv_vector_handler) 732 733#endif /* CONFIG_HYPERV */ 734 735#ifdef CONFIG_FUNCTION_TRACER 736#ifdef CONFIG_DYNAMIC_FTRACE 737 738ENTRY(mcount) 739 ret 740END(mcount) 741 742ENTRY(ftrace_caller) 743 pushl %eax 744 pushl %ecx 745 pushl %edx 746 pushl $0 /* Pass NULL as regs pointer */ 747 movl 4*4(%esp), %eax 748 movl 0x4(%ebp), %edx 749 movl function_trace_op, %ecx 750 subl $MCOUNT_INSN_SIZE, %eax 751 752.globl ftrace_call 753ftrace_call: 754 call ftrace_stub 755 756 addl $4, %esp /* skip NULL pointer */ 757 popl %edx 758 popl %ecx 759 popl %eax 760ftrace_ret: 761#ifdef CONFIG_FUNCTION_GRAPH_TRACER 762.globl ftrace_graph_call 763ftrace_graph_call: 764 jmp ftrace_stub 765#endif 766 767/* This is weak to keep gas from relaxing the jumps */ 768WEAK(ftrace_stub) 769 ret 770END(ftrace_caller) 771 772ENTRY(ftrace_regs_caller) 773 pushf /* push flags before compare (in cs location) */ 774 775 /* 776 * i386 does not save SS and ESP when coming from kernel. 777 * Instead, to get sp, ®s->sp is used (see ptrace.h). 778 * Unfortunately, that means eflags must be at the same location 779 * as the current return ip is. We move the return ip into the 780 * ip location, and move flags into the return ip location. 781 */ 782 pushl 4(%esp) /* save return ip into ip slot */ 783 784 pushl $0 /* Load 0 into orig_ax */ 785 pushl %gs 786 pushl %fs 787 pushl %es 788 pushl %ds 789 pushl %eax 790 pushl %ebp 791 pushl %edi 792 pushl %esi 793 pushl %edx 794 pushl %ecx 795 pushl %ebx 796 797 movl 13*4(%esp), %eax /* Get the saved flags */ 798 movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */ 799 /* clobbering return ip */ 800 movl $__KERNEL_CS, 13*4(%esp) 801 802 movl 12*4(%esp), %eax /* Load ip (1st parameter) */ 803 subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */ 804 movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ 805 movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ 806 pushl %esp /* Save pt_regs as 4th parameter */ 807 808GLOBAL(ftrace_regs_call) 809 call ftrace_stub 810 811 addl $4, %esp /* Skip pt_regs */ 812 movl 14*4(%esp), %eax /* Move flags back into cs */ 813 movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */ 814 movl 12*4(%esp), %eax /* Get return ip from regs->ip */ 815 movl %eax, 14*4(%esp) /* Put return ip back for ret */ 816 817 popl %ebx 818 popl %ecx 819 popl %edx 820 popl %esi 821 popl %edi 822 popl %ebp 823 popl %eax 824 popl %ds 825 popl %es 826 popl %fs 827 popl %gs 828 addl $8, %esp /* Skip orig_ax and ip */ 829 popf /* Pop flags at end (no addl to corrupt flags) */ 830 jmp ftrace_ret 831 832 popf 833 jmp ftrace_stub 834#else /* ! CONFIG_DYNAMIC_FTRACE */ 835 836ENTRY(mcount) 837 cmpl $__PAGE_OFFSET, %esp 838 jb ftrace_stub /* Paging not enabled yet? */ 839 840 cmpl $ftrace_stub, ftrace_trace_function 841 jnz trace 842#ifdef CONFIG_FUNCTION_GRAPH_TRACER 843 cmpl $ftrace_stub, ftrace_graph_return 844 jnz ftrace_graph_caller 845 846 cmpl $ftrace_graph_entry_stub, ftrace_graph_entry 847 jnz ftrace_graph_caller 848#endif 849.globl ftrace_stub 850ftrace_stub: 851 ret 852 853 /* taken from glibc */ 854trace: 855 pushl %eax 856 pushl %ecx 857 pushl %edx 858 movl 0xc(%esp), %eax 859 movl 0x4(%ebp), %edx 860 subl $MCOUNT_INSN_SIZE, %eax 861 862 movl ftrace_trace_function, %ecx 863 CALL_NOSPEC %ecx 864 865 popl %edx 866 popl %ecx 867 popl %eax 868 jmp ftrace_stub 869END(mcount) 870#endif /* CONFIG_DYNAMIC_FTRACE */ 871#endif /* CONFIG_FUNCTION_TRACER */ 872 873#ifdef CONFIG_FUNCTION_GRAPH_TRACER 874ENTRY(ftrace_graph_caller) 875 pushl %eax 876 pushl %ecx 877 pushl %edx 878 movl 0xc(%esp), %eax 879 lea 0x4(%ebp), %edx 880 movl (%ebp), %ecx 881 subl $MCOUNT_INSN_SIZE, %eax 882 call prepare_ftrace_return 883 popl %edx 884 popl %ecx 885 popl %eax 886 ret 887END(ftrace_graph_caller) 888 889.globl return_to_handler 890return_to_handler: 891 pushl %eax 892 pushl %edx 893 movl %ebp, %eax 894 call ftrace_return_to_handler 895 movl %eax, %ecx 896 popl %edx 897 popl %eax 898 JMP_NOSPEC %ecx 899#endif 900 901#ifdef CONFIG_TRACING 902ENTRY(trace_page_fault) 903 ASM_CLAC 904 pushl $trace_do_page_fault 905 jmp error_code 906END(trace_page_fault) 907#endif 908 909ENTRY(page_fault) 910 ASM_CLAC 911 pushl $do_page_fault 912 ALIGN 913error_code: 914 /* the function address is in %gs's slot on the stack */ 915 pushl %fs 916 pushl %es 917 pushl %ds 918 pushl %eax 919 pushl %ebp 920 pushl %edi 921 pushl %esi 922 pushl %edx 923 pushl %ecx 924 pushl %ebx 925 cld 926 movl $(__KERNEL_PERCPU), %ecx 927 movl %ecx, %fs 928 UNWIND_ESPFIX_STACK 929 GS_TO_REG %ecx 930 movl PT_GS(%esp), %edi # get the function address 931 movl PT_ORIG_EAX(%esp), %edx # get the error code 932 movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart 933 REG_TO_PTGS %ecx 934 SET_KERNEL_GS %ecx 935 movl $(__USER_DS), %ecx 936 movl %ecx, %ds 937 movl %ecx, %es 938 TRACE_IRQS_OFF 939 movl %esp, %eax # pt_regs pointer 940 CALL_NOSPEC %edi 941 jmp ret_from_exception 942END(page_fault) 943 944/* 945 * Debug traps and NMI can happen at the one SYSENTER instruction 946 * that sets up the real kernel stack. Check here, since we can't 947 * allow the wrong stack to be used. 948 * 949 * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have 950 * already pushed 3 words if it hits on the sysenter instruction: 951 * eflags, cs and eip. 952 * 953 * We just load the right stack, and push the three (known) values 954 * by hand onto the new stack - while updating the return eip past 955 * the instruction that would have done it for sysenter. 956 */ 957.macro FIX_STACK offset ok label 958 cmpw $__KERNEL_CS, 4(%esp) 959 jne \ok 960\label: 961 movl TSS_sysenter_sp0 + \offset(%esp), %esp 962 pushfl 963 pushl $__KERNEL_CS 964 pushl $sysenter_past_esp 965.endm 966 967ENTRY(debug) 968 ASM_CLAC 969 cmpl $entry_SYSENTER_32, (%esp) 970 jne debug_stack_correct 971 FIX_STACK 12, debug_stack_correct, debug_esp_fix_insn 972debug_stack_correct: 973 pushl $-1 # mark this as an int 974 SAVE_ALL 975 TRACE_IRQS_OFF 976 xorl %edx, %edx # error code 0 977 movl %esp, %eax # pt_regs pointer 978 call do_debug 979 jmp ret_from_exception 980END(debug) 981 982/* 983 * NMI is doubly nasty. It can happen _while_ we're handling 984 * a debug fault, and the debug fault hasn't yet been able to 985 * clear up the stack. So we first check whether we got an 986 * NMI on the sysenter entry path, but after that we need to 987 * check whether we got an NMI on the debug path where the debug 988 * fault happened on the sysenter path. 989 */ 990ENTRY(nmi) 991 ASM_CLAC 992#ifdef CONFIG_X86_ESPFIX32 993 pushl %eax 994 movl %ss, %eax 995 cmpw $__ESPFIX_SS, %ax 996 popl %eax 997 je nmi_espfix_stack 998#endif 999 cmpl $entry_SYSENTER_32, (%esp) 1000 je nmi_stack_fixup 1001 pushl %eax 1002 movl %esp, %eax 1003 /* 1004 * Do not access memory above the end of our stack page, 1005 * it might not exist. 1006 */ 1007 andl $(THREAD_SIZE-1), %eax 1008 cmpl $(THREAD_SIZE-20), %eax 1009 popl %eax 1010 jae nmi_stack_correct 1011 cmpl $entry_SYSENTER_32, 12(%esp) 1012 je nmi_debug_stack_check 1013nmi_stack_correct: 1014 pushl %eax 1015 SAVE_ALL 1016 xorl %edx, %edx # zero error code 1017 movl %esp, %eax # pt_regs pointer 1018 call do_nmi 1019 jmp restore_all_notrace 1020 1021nmi_stack_fixup: 1022 FIX_STACK 12, nmi_stack_correct, 1 1023 jmp nmi_stack_correct 1024 1025nmi_debug_stack_check: 1026 cmpw $__KERNEL_CS, 16(%esp) 1027 jne nmi_stack_correct 1028 cmpl $debug, (%esp) 1029 jb nmi_stack_correct 1030 cmpl $debug_esp_fix_insn, (%esp) 1031 ja nmi_stack_correct 1032 FIX_STACK 24, nmi_stack_correct, 1 1033 jmp nmi_stack_correct 1034 1035#ifdef CONFIG_X86_ESPFIX32 1036nmi_espfix_stack: 1037 /* 1038 * create the pointer to lss back 1039 */ 1040 pushl %ss 1041 pushl %esp 1042 addl $4, (%esp) 1043 /* copy the iret frame of 12 bytes */ 1044 .rept 3 1045 pushl 16(%esp) 1046 .endr 1047 pushl %eax 1048 SAVE_ALL 1049 FIXUP_ESPFIX_STACK # %eax == %esp 1050 xorl %edx, %edx # zero error code 1051 call do_nmi 1052 RESTORE_REGS 1053 lss 12+4(%esp), %esp # back to espfix stack 1054 jmp irq_return 1055#endif 1056END(nmi) 1057 1058ENTRY(int3) 1059 ASM_CLAC 1060 pushl $-1 # mark this as an int 1061 SAVE_ALL 1062 TRACE_IRQS_OFF 1063 xorl %edx, %edx # zero error code 1064 movl %esp, %eax # pt_regs pointer 1065 call do_int3 1066 jmp ret_from_exception 1067END(int3) 1068 1069ENTRY(general_protection) 1070 ASM_CLAC 1071 pushl $do_general_protection 1072 jmp error_code 1073END(general_protection) 1074 1075#ifdef CONFIG_KVM_GUEST 1076ENTRY(async_page_fault) 1077 ASM_CLAC 1078 pushl $do_async_page_fault 1079 jmp error_code 1080END(async_page_fault) 1081#endif 1082