linux/arch/x86/kernel/entry_32.S
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   1/*
   2 *
   3 *  Copyright (C) 1991, 1992  Linus Torvalds
   4 */
   5
   6/*
   7 * entry.S contains the system-call and fault low-level handling routines.
   8 * This also contains the timer-interrupt handler, as well as all interrupts
   9 * and faults that can result in a task-switch.
  10 *
  11 * NOTE: This code handles signal-recognition, which happens every time
  12 * after a timer-interrupt and after each system call.
  13 *
  14 * I changed all the .align's to 4 (16 byte alignment), as that's faster
  15 * on a 486.
  16 *
  17 * Stack layout in 'syscall_exit':
  18 *      ptrace needs to have all regs on the stack.
  19 *      if the order here is changed, it needs to be
  20 *      updated in fork.c:copy_process, signal.c:do_signal,
  21 *      ptrace.c and ptrace.h
  22 *
  23 *       0(%esp) - %ebx
  24 *       4(%esp) - %ecx
  25 *       8(%esp) - %edx
  26 *       C(%esp) - %esi
  27 *      10(%esp) - %edi
  28 *      14(%esp) - %ebp
  29 *      18(%esp) - %eax
  30 *      1C(%esp) - %ds
  31 *      20(%esp) - %es
  32 *      24(%esp) - %fs
  33 *      28(%esp) - %gs          saved iff !CONFIG_X86_32_LAZY_GS
  34 *      2C(%esp) - orig_eax
  35 *      30(%esp) - %eip
  36 *      34(%esp) - %cs
  37 *      38(%esp) - %eflags
  38 *      3C(%esp) - %oldesp
  39 *      40(%esp) - %oldss
  40 *
  41 * "current" is in register %ebx during any slow entries.
  42 */
  43
  44#include <linux/linkage.h>
  45#include <asm/thread_info.h>
  46#include <asm/irqflags.h>
  47#include <asm/errno.h>
  48#include <asm/segment.h>
  49#include <asm/smp.h>
  50#include <asm/page_types.h>
  51#include <asm/percpu.h>
  52#include <asm/dwarf2.h>
  53#include <asm/processor-flags.h>
  54#include <asm/ftrace.h>
  55#include <asm/irq_vectors.h>
  56#include <asm/cpufeature.h>
  57#include <asm/alternative-asm.h>
  58
  59/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
  60#include <linux/elf-em.h>
  61#define AUDIT_ARCH_I386         (EM_386|__AUDIT_ARCH_LE)
  62#define __AUDIT_ARCH_LE    0x40000000
  63
  64#ifndef CONFIG_AUDITSYSCALL
  65#define sysenter_audit  syscall_trace_entry
  66#define sysexit_audit   syscall_exit_work
  67#endif
  68
  69        .section .entry.text, "ax"
  70
  71/*
  72 * We use macros for low-level operations which need to be overridden
  73 * for paravirtualization.  The following will never clobber any registers:
  74 *   INTERRUPT_RETURN (aka. "iret")
  75 *   GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
  76 *   ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
  77 *
  78 * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
  79 * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
  80 * Allowing a register to be clobbered can shrink the paravirt replacement
  81 * enough to patch inline, increasing performance.
  82 */
  83
  84#define nr_syscalls ((syscall_table_size)/4)
  85
  86#ifdef CONFIG_PREEMPT
  87#define preempt_stop(clobbers)  DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
  88#else
  89#define preempt_stop(clobbers)
  90#define resume_kernel           restore_all
  91#endif
  92
  93.macro TRACE_IRQS_IRET
  94#ifdef CONFIG_TRACE_IRQFLAGS
  95        testl $X86_EFLAGS_IF,PT_EFLAGS(%esp)     # interrupts off?
  96        jz 1f
  97        TRACE_IRQS_ON
  981:
  99#endif
 100.endm
 101
 102#ifdef CONFIG_VM86
 103#define resume_userspace_sig    check_userspace
 104#else
 105#define resume_userspace_sig    resume_userspace
 106#endif
 107
 108/*
 109 * User gs save/restore
 110 *
 111 * %gs is used for userland TLS and kernel only uses it for stack
 112 * canary which is required to be at %gs:20 by gcc.  Read the comment
 113 * at the top of stackprotector.h for more info.
 114 *
 115 * Local labels 98 and 99 are used.
 116 */
 117#ifdef CONFIG_X86_32_LAZY_GS
 118
 119 /* unfortunately push/pop can't be no-op */
 120.macro PUSH_GS
 121        pushl_cfi $0
 122.endm
 123.macro POP_GS pop=0
 124        addl $(4 + \pop), %esp
 125        CFI_ADJUST_CFA_OFFSET -(4 + \pop)
 126.endm
 127.macro POP_GS_EX
 128.endm
 129
 130 /* all the rest are no-op */
 131.macro PTGS_TO_GS
 132.endm
 133.macro PTGS_TO_GS_EX
 134.endm
 135.macro GS_TO_REG reg
 136.endm
 137.macro REG_TO_PTGS reg
 138.endm
 139.macro SET_KERNEL_GS reg
 140.endm
 141
 142#else   /* CONFIG_X86_32_LAZY_GS */
 143
 144.macro PUSH_GS
 145        pushl_cfi %gs
 146        /*CFI_REL_OFFSET gs, 0*/
 147.endm
 148
 149.macro POP_GS pop=0
 15098:     popl_cfi %gs
 151        /*CFI_RESTORE gs*/
 152  .if \pop <> 0
 153        add $\pop, %esp
 154        CFI_ADJUST_CFA_OFFSET -\pop
 155  .endif
 156.endm
 157.macro POP_GS_EX
 158.pushsection .fixup, "ax"
 15999:     movl $0, (%esp)
 160        jmp 98b
 161.section __ex_table, "a"
 162        .align 4
 163        .long 98b, 99b
 164.popsection
 165.endm
 166
 167.macro PTGS_TO_GS
 16898:     mov PT_GS(%esp), %gs
 169.endm
 170.macro PTGS_TO_GS_EX
 171.pushsection .fixup, "ax"
 17299:     movl $0, PT_GS(%esp)
 173        jmp 98b
 174.section __ex_table, "a"
 175        .align 4
 176        .long 98b, 99b
 177.popsection
 178.endm
 179
 180.macro GS_TO_REG reg
 181        movl %gs, \reg
 182        /*CFI_REGISTER gs, \reg*/
 183.endm
 184.macro REG_TO_PTGS reg
 185        movl \reg, PT_GS(%esp)
 186        /*CFI_REL_OFFSET gs, PT_GS*/
 187.endm
 188.macro SET_KERNEL_GS reg
 189        movl $(__KERNEL_STACK_CANARY), \reg
 190        movl \reg, %gs
 191.endm
 192
 193#endif  /* CONFIG_X86_32_LAZY_GS */
 194
 195.macro SAVE_ALL
 196        cld
 197        PUSH_GS
 198        pushl_cfi %fs
 199        /*CFI_REL_OFFSET fs, 0;*/
 200        pushl_cfi %es
 201        /*CFI_REL_OFFSET es, 0;*/
 202        pushl_cfi %ds
 203        /*CFI_REL_OFFSET ds, 0;*/
 204        pushl_cfi %eax
 205        CFI_REL_OFFSET eax, 0
 206        pushl_cfi %ebp
 207        CFI_REL_OFFSET ebp, 0
 208        pushl_cfi %edi
 209        CFI_REL_OFFSET edi, 0
 210        pushl_cfi %esi
 211        CFI_REL_OFFSET esi, 0
 212        pushl_cfi %edx
 213        CFI_REL_OFFSET edx, 0
 214        pushl_cfi %ecx
 215        CFI_REL_OFFSET ecx, 0
 216        pushl_cfi %ebx
 217        CFI_REL_OFFSET ebx, 0
 218        movl $(__USER_DS), %edx
 219        movl %edx, %ds
 220        movl %edx, %es
 221        movl $(__KERNEL_PERCPU), %edx
 222        movl %edx, %fs
 223        SET_KERNEL_GS %edx
 224.endm
 225
 226.macro RESTORE_INT_REGS
 227        popl_cfi %ebx
 228        CFI_RESTORE ebx
 229        popl_cfi %ecx
 230        CFI_RESTORE ecx
 231        popl_cfi %edx
 232        CFI_RESTORE edx
 233        popl_cfi %esi
 234        CFI_RESTORE esi
 235        popl_cfi %edi
 236        CFI_RESTORE edi
 237        popl_cfi %ebp
 238        CFI_RESTORE ebp
 239        popl_cfi %eax
 240        CFI_RESTORE eax
 241.endm
 242
 243.macro RESTORE_REGS pop=0
 244        RESTORE_INT_REGS
 2451:      popl_cfi %ds
 246        /*CFI_RESTORE ds;*/
 2472:      popl_cfi %es
 248        /*CFI_RESTORE es;*/
 2493:      popl_cfi %fs
 250        /*CFI_RESTORE fs;*/
 251        POP_GS \pop
 252.pushsection .fixup, "ax"
 2534:      movl $0, (%esp)
 254        jmp 1b
 2555:      movl $0, (%esp)
 256        jmp 2b
 2576:      movl $0, (%esp)
 258        jmp 3b
 259.section __ex_table, "a"
 260        .align 4
 261        .long 1b, 4b
 262        .long 2b, 5b
 263        .long 3b, 6b
 264.popsection
 265        POP_GS_EX
 266.endm
 267
 268.macro RING0_INT_FRAME
 269        CFI_STARTPROC simple
 270        CFI_SIGNAL_FRAME
 271        CFI_DEF_CFA esp, 3*4
 272        /*CFI_OFFSET cs, -2*4;*/
 273        CFI_OFFSET eip, -3*4
 274.endm
 275
 276.macro RING0_EC_FRAME
 277        CFI_STARTPROC simple
 278        CFI_SIGNAL_FRAME
 279        CFI_DEF_CFA esp, 4*4
 280        /*CFI_OFFSET cs, -2*4;*/
 281        CFI_OFFSET eip, -3*4
 282.endm
 283
 284.macro RING0_PTREGS_FRAME
 285        CFI_STARTPROC simple
 286        CFI_SIGNAL_FRAME
 287        CFI_DEF_CFA esp, PT_OLDESP-PT_EBX
 288        /*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/
 289        CFI_OFFSET eip, PT_EIP-PT_OLDESP
 290        /*CFI_OFFSET es, PT_ES-PT_OLDESP;*/
 291        /*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/
 292        CFI_OFFSET eax, PT_EAX-PT_OLDESP
 293        CFI_OFFSET ebp, PT_EBP-PT_OLDESP
 294        CFI_OFFSET edi, PT_EDI-PT_OLDESP
 295        CFI_OFFSET esi, PT_ESI-PT_OLDESP
 296        CFI_OFFSET edx, PT_EDX-PT_OLDESP
 297        CFI_OFFSET ecx, PT_ECX-PT_OLDESP
 298        CFI_OFFSET ebx, PT_EBX-PT_OLDESP
 299.endm
 300
 301ENTRY(ret_from_fork)
 302        CFI_STARTPROC
 303        pushl_cfi %eax
 304        call schedule_tail
 305        GET_THREAD_INFO(%ebp)
 306        popl_cfi %eax
 307        pushl_cfi $0x0202               # Reset kernel eflags
 308        popfl_cfi
 309        jmp syscall_exit
 310        CFI_ENDPROC
 311END(ret_from_fork)
 312
 313/*
 314 * Interrupt exit functions should be protected against kprobes
 315 */
 316        .pushsection .kprobes.text, "ax"
 317/*
 318 * Return to user mode is not as complex as all this looks,
 319 * but we want the default path for a system call return to
 320 * go as quickly as possible which is why some of this is
 321 * less clear than it otherwise should be.
 322 */
 323
 324        # userspace resumption stub bypassing syscall exit tracing
 325        ALIGN
 326        RING0_PTREGS_FRAME
 327ret_from_exception:
 328        preempt_stop(CLBR_ANY)
 329ret_from_intr:
 330        GET_THREAD_INFO(%ebp)
 331check_userspace:
 332        movl PT_EFLAGS(%esp), %eax      # mix EFLAGS and CS
 333        movb PT_CS(%esp), %al
 334        andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
 335        cmpl $USER_RPL, %eax
 336        jb resume_kernel                # not returning to v8086 or userspace
 337
 338ENTRY(resume_userspace)
 339        LOCKDEP_SYS_EXIT
 340        DISABLE_INTERRUPTS(CLBR_ANY)    # make sure we don't miss an interrupt
 341                                        # setting need_resched or sigpending
 342                                        # between sampling and the iret
 343        TRACE_IRQS_OFF
 344        movl TI_flags(%ebp), %ecx
 345        andl $_TIF_WORK_MASK, %ecx      # is there any work to be done on
 346                                        # int/exception return?
 347        jne work_pending
 348        jmp restore_all
 349END(ret_from_exception)
 350
 351#ifdef CONFIG_PREEMPT
 352ENTRY(resume_kernel)
 353        DISABLE_INTERRUPTS(CLBR_ANY)
 354        cmpl $0,TI_preempt_count(%ebp)  # non-zero preempt_count ?
 355        jnz restore_all
 356need_resched:
 357        movl TI_flags(%ebp), %ecx       # need_resched set ?
 358        testb $_TIF_NEED_RESCHED, %cl
 359        jz restore_all
 360        testl $X86_EFLAGS_IF,PT_EFLAGS(%esp)    # interrupts off (exception path) ?
 361        jz restore_all
 362        call preempt_schedule_irq
 363        jmp need_resched
 364END(resume_kernel)
 365#endif
 366        CFI_ENDPROC
 367/*
 368 * End of kprobes section
 369 */
 370        .popsection
 371
 372/* SYSENTER_RETURN points to after the "sysenter" instruction in
 373   the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */
 374
 375        # sysenter call handler stub
 376ENTRY(ia32_sysenter_target)
 377        CFI_STARTPROC simple
 378        CFI_SIGNAL_FRAME
 379        CFI_DEF_CFA esp, 0
 380        CFI_REGISTER esp, ebp
 381        movl TSS_sysenter_sp0(%esp),%esp
 382sysenter_past_esp:
 383        /*
 384         * Interrupts are disabled here, but we can't trace it until
 385         * enough kernel state to call TRACE_IRQS_OFF can be called - but
 386         * we immediately enable interrupts at that point anyway.
 387         */
 388        pushl_cfi $__USER_DS
 389        /*CFI_REL_OFFSET ss, 0*/
 390        pushl_cfi %ebp
 391        CFI_REL_OFFSET esp, 0
 392        pushfl_cfi
 393        orl $X86_EFLAGS_IF, (%esp)
 394        pushl_cfi $__USER_CS
 395        /*CFI_REL_OFFSET cs, 0*/
 396        /*
 397         * Push current_thread_info()->sysenter_return to the stack.
 398         * A tiny bit of offset fixup is necessary - 4*4 means the 4 words
 399         * pushed above; +8 corresponds to copy_thread's esp0 setting.
 400         */
 401        pushl_cfi ((TI_sysenter_return)-THREAD_SIZE+8+4*4)(%esp)
 402        CFI_REL_OFFSET eip, 0
 403
 404        pushl_cfi %eax
 405        SAVE_ALL
 406        ENABLE_INTERRUPTS(CLBR_NONE)
 407
 408/*
 409 * Load the potential sixth argument from user stack.
 410 * Careful about security.
 411 */
 412        cmpl $__PAGE_OFFSET-3,%ebp
 413        jae syscall_fault
 4141:      movl (%ebp),%ebp
 415        movl %ebp,PT_EBP(%esp)
 416.section __ex_table,"a"
 417        .align 4
 418        .long 1b,syscall_fault
 419.previous
 420
 421        GET_THREAD_INFO(%ebp)
 422
 423        testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
 424        jnz sysenter_audit
 425sysenter_do_call:
 426        cmpl $(nr_syscalls), %eax
 427        jae syscall_badsys
 428        call *sys_call_table(,%eax,4)
 429        movl %eax,PT_EAX(%esp)
 430        LOCKDEP_SYS_EXIT
 431        DISABLE_INTERRUPTS(CLBR_ANY)
 432        TRACE_IRQS_OFF
 433        movl TI_flags(%ebp), %ecx
 434        testl $_TIF_ALLWORK_MASK, %ecx
 435        jne sysexit_audit
 436sysenter_exit:
 437/* if something modifies registers it must also disable sysexit */
 438        movl PT_EIP(%esp), %edx
 439        movl PT_OLDESP(%esp), %ecx
 440        xorl %ebp,%ebp
 441        TRACE_IRQS_ON
 4421:      mov  PT_FS(%esp), %fs
 443        PTGS_TO_GS
 444        ENABLE_INTERRUPTS_SYSEXIT
 445
 446#ifdef CONFIG_AUDITSYSCALL
 447sysenter_audit:
 448        testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
 449        jnz syscall_trace_entry
 450        addl $4,%esp
 451        CFI_ADJUST_CFA_OFFSET -4
 452        /* %esi already in 8(%esp)         6th arg: 4th syscall arg */
 453        /* %edx already in 4(%esp)         5th arg: 3rd syscall arg */
 454        /* %ecx already in 0(%esp)         4th arg: 2nd syscall arg */
 455        movl %ebx,%ecx                  /* 3rd arg: 1st syscall arg */
 456        movl %eax,%edx                  /* 2nd arg: syscall number */
 457        movl $AUDIT_ARCH_I386,%eax      /* 1st arg: audit arch */
 458        call audit_syscall_entry
 459        pushl_cfi %ebx
 460        movl PT_EAX(%esp),%eax          /* reload syscall number */
 461        jmp sysenter_do_call
 462
 463sysexit_audit:
 464        testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx
 465        jne syscall_exit_work
 466        TRACE_IRQS_ON
 467        ENABLE_INTERRUPTS(CLBR_ANY)
 468        movl %eax,%edx          /* second arg, syscall return value */
 469        cmpl $0,%eax            /* is it < 0? */
 470        setl %al                /* 1 if so, 0 if not */
 471        movzbl %al,%eax         /* zero-extend that */
 472        inc %eax /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
 473        call audit_syscall_exit
 474        DISABLE_INTERRUPTS(CLBR_ANY)
 475        TRACE_IRQS_OFF
 476        movl TI_flags(%ebp), %ecx
 477        testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx
 478        jne syscall_exit_work
 479        movl PT_EAX(%esp),%eax  /* reload syscall return value */
 480        jmp sysenter_exit
 481#endif
 482
 483        CFI_ENDPROC
 484.pushsection .fixup,"ax"
 4852:      movl $0,PT_FS(%esp)
 486        jmp 1b
 487.section __ex_table,"a"
 488        .align 4
 489        .long 1b,2b
 490.popsection
 491        PTGS_TO_GS_EX
 492ENDPROC(ia32_sysenter_target)
 493
 494/*
 495 * syscall stub including irq exit should be protected against kprobes
 496 */
 497        .pushsection .kprobes.text, "ax"
 498        # system call handler stub
 499ENTRY(system_call)
 500        RING0_INT_FRAME                 # can't unwind into user space anyway
 501        pushl_cfi %eax                  # save orig_eax
 502        SAVE_ALL
 503        GET_THREAD_INFO(%ebp)
 504                                        # system call tracing in operation / emulation
 505        testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
 506        jnz syscall_trace_entry
 507        cmpl $(nr_syscalls), %eax
 508        jae syscall_badsys
 509syscall_call:
 510        call *sys_call_table(,%eax,4)
 511        movl %eax,PT_EAX(%esp)          # store the return value
 512syscall_exit:
 513        LOCKDEP_SYS_EXIT
 514        DISABLE_INTERRUPTS(CLBR_ANY)    # make sure we don't miss an interrupt
 515                                        # setting need_resched or sigpending
 516                                        # between sampling and the iret
 517        TRACE_IRQS_OFF
 518        movl TI_flags(%ebp), %ecx
 519        testl $_TIF_ALLWORK_MASK, %ecx  # current->work
 520        jne syscall_exit_work
 521
 522restore_all:
 523        TRACE_IRQS_IRET
 524restore_all_notrace:
 525        movl PT_EFLAGS(%esp), %eax      # mix EFLAGS, SS and CS
 526        # Warning: PT_OLDSS(%esp) contains the wrong/random values if we
 527        # are returning to the kernel.
 528        # See comments in process.c:copy_thread() for details.
 529        movb PT_OLDSS(%esp), %ah
 530        movb PT_CS(%esp), %al
 531        andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
 532        cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax
 533        CFI_REMEMBER_STATE
 534        je ldt_ss                       # returning to user-space with LDT SS
 535restore_nocheck:
 536        RESTORE_REGS 4                  # skip orig_eax/error_code
 537irq_return:
 538        INTERRUPT_RETURN
 539.section .fixup,"ax"
 540ENTRY(iret_exc)
 541        pushl $0                        # no error code
 542        pushl $do_iret_error
 543        jmp error_code
 544.previous
 545.section __ex_table,"a"
 546        .align 4
 547        .long irq_return,iret_exc
 548.previous
 549
 550        CFI_RESTORE_STATE
 551ldt_ss:
 552        larl PT_OLDSS(%esp), %eax
 553        jnz restore_nocheck
 554        testl $0x00400000, %eax         # returning to 32bit stack?
 555        jnz restore_nocheck             # allright, normal return
 556
 557#ifdef CONFIG_PARAVIRT
 558        /*
 559         * The kernel can't run on a non-flat stack if paravirt mode
 560         * is active.  Rather than try to fixup the high bits of
 561         * ESP, bypass this code entirely.  This may break DOSemu
 562         * and/or Wine support in a paravirt VM, although the option
 563         * is still available to implement the setting of the high
 564         * 16-bits in the INTERRUPT_RETURN paravirt-op.
 565         */
 566        cmpl $0, pv_info+PARAVIRT_enabled
 567        jne restore_nocheck
 568#endif
 569
 570/*
 571 * Setup and switch to ESPFIX stack
 572 *
 573 * We're returning to userspace with a 16 bit stack. The CPU will not
 574 * restore the high word of ESP for us on executing iret... This is an
 575 * "official" bug of all the x86-compatible CPUs, which we can work
 576 * around to make dosemu and wine happy. We do this by preloading the
 577 * high word of ESP with the high word of the userspace ESP while
 578 * compensating for the offset by changing to the ESPFIX segment with
 579 * a base address that matches for the difference.
 580 */
 581#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8)
 582        mov %esp, %edx                  /* load kernel esp */
 583        mov PT_OLDESP(%esp), %eax       /* load userspace esp */
 584        mov %dx, %ax                    /* eax: new kernel esp */
 585        sub %eax, %edx                  /* offset (low word is 0) */
 586        shr $16, %edx
 587        mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */
 588        mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */
 589        pushl_cfi $__ESPFIX_SS
 590        pushl_cfi %eax                  /* new kernel esp */
 591        /* Disable interrupts, but do not irqtrace this section: we
 592         * will soon execute iret and the tracer was already set to
 593         * the irqstate after the iret */
 594        DISABLE_INTERRUPTS(CLBR_EAX)
 595        lss (%esp), %esp                /* switch to espfix segment */
 596        CFI_ADJUST_CFA_OFFSET -8
 597        jmp restore_nocheck
 598        CFI_ENDPROC
 599ENDPROC(system_call)
 600
 601        # perform work that needs to be done immediately before resumption
 602        ALIGN
 603        RING0_PTREGS_FRAME              # can't unwind into user space anyway
 604work_pending:
 605        testb $_TIF_NEED_RESCHED, %cl
 606        jz work_notifysig
 607work_resched:
 608        call schedule
 609        LOCKDEP_SYS_EXIT
 610        DISABLE_INTERRUPTS(CLBR_ANY)    # make sure we don't miss an interrupt
 611                                        # setting need_resched or sigpending
 612                                        # between sampling and the iret
 613        TRACE_IRQS_OFF
 614        movl TI_flags(%ebp), %ecx
 615        andl $_TIF_WORK_MASK, %ecx      # is there any work to be done other
 616                                        # than syscall tracing?
 617        jz restore_all
 618        testb $_TIF_NEED_RESCHED, %cl
 619        jnz work_resched
 620
 621work_notifysig:                         # deal with pending signals and
 622                                        # notify-resume requests
 623#ifdef CONFIG_VM86
 624        testl $X86_EFLAGS_VM, PT_EFLAGS(%esp)
 625        movl %esp, %eax
 626        jne work_notifysig_v86          # returning to kernel-space or
 627                                        # vm86-space
 628        xorl %edx, %edx
 629        call do_notify_resume
 630        jmp resume_userspace_sig
 631
 632        ALIGN
 633work_notifysig_v86:
 634        pushl_cfi %ecx                  # save ti_flags for do_notify_resume
 635        call save_v86_state             # %eax contains pt_regs pointer
 636        popl_cfi %ecx
 637        movl %eax, %esp
 638#else
 639        movl %esp, %eax
 640#endif
 641        xorl %edx, %edx
 642        call do_notify_resume
 643        jmp resume_userspace_sig
 644END(work_pending)
 645
 646        # perform syscall exit tracing
 647        ALIGN
 648syscall_trace_entry:
 649        movl $-ENOSYS,PT_EAX(%esp)
 650        movl %esp, %eax
 651        call syscall_trace_enter
 652        /* What it returned is what we'll actually use.  */
 653        cmpl $(nr_syscalls), %eax
 654        jnae syscall_call
 655        jmp syscall_exit
 656END(syscall_trace_entry)
 657
 658        # perform syscall exit tracing
 659        ALIGN
 660syscall_exit_work:
 661        testl $_TIF_WORK_SYSCALL_EXIT, %ecx
 662        jz work_pending
 663        TRACE_IRQS_ON
 664        ENABLE_INTERRUPTS(CLBR_ANY)     # could let syscall_trace_leave() call
 665                                        # schedule() instead
 666        movl %esp, %eax
 667        call syscall_trace_leave
 668        jmp resume_userspace
 669END(syscall_exit_work)
 670        CFI_ENDPROC
 671
 672        RING0_INT_FRAME                 # can't unwind into user space anyway
 673syscall_fault:
 674        GET_THREAD_INFO(%ebp)
 675        movl $-EFAULT,PT_EAX(%esp)
 676        jmp resume_userspace
 677END(syscall_fault)
 678
 679syscall_badsys:
 680        movl $-ENOSYS,PT_EAX(%esp)
 681        jmp resume_userspace
 682END(syscall_badsys)
 683        CFI_ENDPROC
 684/*
 685 * End of kprobes section
 686 */
 687        .popsection
 688
 689/*
 690 * System calls that need a pt_regs pointer.
 691 */
 692#define PTREGSCALL0(name) \
 693        ALIGN; \
 694ptregs_##name: \
 695        leal 4(%esp),%eax; \
 696        jmp sys_##name;
 697
 698#define PTREGSCALL1(name) \
 699        ALIGN; \
 700ptregs_##name: \
 701        leal 4(%esp),%edx; \
 702        movl (PT_EBX+4)(%esp),%eax; \
 703        jmp sys_##name;
 704
 705#define PTREGSCALL2(name) \
 706        ALIGN; \
 707ptregs_##name: \
 708        leal 4(%esp),%ecx; \
 709        movl (PT_ECX+4)(%esp),%edx; \
 710        movl (PT_EBX+4)(%esp),%eax; \
 711        jmp sys_##name;
 712
 713#define PTREGSCALL3(name) \
 714        ALIGN; \
 715ptregs_##name: \
 716        CFI_STARTPROC; \
 717        leal 4(%esp),%eax; \
 718        pushl_cfi %eax; \
 719        movl PT_EDX(%eax),%ecx; \
 720        movl PT_ECX(%eax),%edx; \
 721        movl PT_EBX(%eax),%eax; \
 722        call sys_##name; \
 723        addl $4,%esp; \
 724        CFI_ADJUST_CFA_OFFSET -4; \
 725        ret; \
 726        CFI_ENDPROC; \
 727ENDPROC(ptregs_##name)
 728
 729PTREGSCALL1(iopl)
 730PTREGSCALL0(fork)
 731PTREGSCALL0(vfork)
 732PTREGSCALL3(execve)
 733PTREGSCALL2(sigaltstack)
 734PTREGSCALL0(sigreturn)
 735PTREGSCALL0(rt_sigreturn)
 736PTREGSCALL2(vm86)
 737PTREGSCALL1(vm86old)
 738
 739/* Clone is an oddball.  The 4th arg is in %edi */
 740        ALIGN;
 741ptregs_clone:
 742        CFI_STARTPROC
 743        leal 4(%esp),%eax
 744        pushl_cfi %eax
 745        pushl_cfi PT_EDI(%eax)
 746        movl PT_EDX(%eax),%ecx
 747        movl PT_ECX(%eax),%edx
 748        movl PT_EBX(%eax),%eax
 749        call sys_clone
 750        addl $8,%esp
 751        CFI_ADJUST_CFA_OFFSET -8
 752        ret
 753        CFI_ENDPROC
 754ENDPROC(ptregs_clone)
 755
 756.macro FIXUP_ESPFIX_STACK
 757/*
 758 * Switch back for ESPFIX stack to the normal zerobased stack
 759 *
 760 * We can't call C functions using the ESPFIX stack. This code reads
 761 * the high word of the segment base from the GDT and swiches to the
 762 * normal stack and adjusts ESP with the matching offset.
 763 */
 764        /* fixup the stack */
 765        mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */
 766        mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */
 767        shl $16, %eax
 768        addl %esp, %eax                 /* the adjusted stack pointer */
 769        pushl_cfi $__KERNEL_DS
 770        pushl_cfi %eax
 771        lss (%esp), %esp                /* switch to the normal stack segment */
 772        CFI_ADJUST_CFA_OFFSET -8
 773.endm
 774.macro UNWIND_ESPFIX_STACK
 775        movl %ss, %eax
 776        /* see if on espfix stack */
 777        cmpw $__ESPFIX_SS, %ax
 778        jne 27f
 779        movl $__KERNEL_DS, %eax
 780        movl %eax, %ds
 781        movl %eax, %es
 782        /* switch to normal stack */
 783        FIXUP_ESPFIX_STACK
 78427:
 785.endm
 786
 787/*
 788 * Build the entry stubs and pointer table with some assembler magic.
 789 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
 790 * single cache line on all modern x86 implementations.
 791 */
 792.section .init.rodata,"a"
 793ENTRY(interrupt)
 794.section .entry.text, "ax"
 795        .p2align 5
 796        .p2align CONFIG_X86_L1_CACHE_SHIFT
 797ENTRY(irq_entries_start)
 798        RING0_INT_FRAME
 799vector=FIRST_EXTERNAL_VECTOR
 800.rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
 801        .balign 32
 802  .rept 7
 803    .if vector < NR_VECTORS
 804      .if vector <> FIRST_EXTERNAL_VECTOR
 805        CFI_ADJUST_CFA_OFFSET -4
 806      .endif
 8071:      pushl_cfi $(~vector+0x80)       /* Note: always in signed byte range */
 808      .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
 809        jmp 2f
 810      .endif
 811      .previous
 812        .long 1b
 813      .section .entry.text, "ax"
 814vector=vector+1
 815    .endif
 816  .endr
 8172:      jmp common_interrupt
 818.endr
 819END(irq_entries_start)
 820
 821.previous
 822END(interrupt)
 823.previous
 824
 825/*
 826 * the CPU automatically disables interrupts when executing an IRQ vector,
 827 * so IRQ-flags tracing has to follow that:
 828 */
 829        .p2align CONFIG_X86_L1_CACHE_SHIFT
 830common_interrupt:
 831        addl $-0x80,(%esp)      /* Adjust vector into the [-256,-1] range */
 832        SAVE_ALL
 833        TRACE_IRQS_OFF
 834        movl %esp,%eax
 835        call do_IRQ
 836        jmp ret_from_intr
 837ENDPROC(common_interrupt)
 838        CFI_ENDPROC
 839
 840/*
 841 *  Irq entries should be protected against kprobes
 842 */
 843        .pushsection .kprobes.text, "ax"
 844#define BUILD_INTERRUPT3(name, nr, fn)  \
 845ENTRY(name)                             \
 846        RING0_INT_FRAME;                \
 847        pushl_cfi $~(nr);               \
 848        SAVE_ALL;                       \
 849        TRACE_IRQS_OFF                  \
 850        movl %esp,%eax;                 \
 851        call fn;                        \
 852        jmp ret_from_intr;              \
 853        CFI_ENDPROC;                    \
 854ENDPROC(name)
 855
 856#define BUILD_INTERRUPT(name, nr)       BUILD_INTERRUPT3(name, nr, smp_##name)
 857
 858/* The include is where all of the SMP etc. interrupts come from */
 859#include <asm/entry_arch.h>
 860
 861ENTRY(coprocessor_error)
 862        RING0_INT_FRAME
 863        pushl_cfi $0
 864        pushl_cfi $do_coprocessor_error
 865        jmp error_code
 866        CFI_ENDPROC
 867END(coprocessor_error)
 868
 869ENTRY(simd_coprocessor_error)
 870        RING0_INT_FRAME
 871        pushl_cfi $0
 872#ifdef CONFIG_X86_INVD_BUG
 873        /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
 874661:    pushl_cfi $do_general_protection
 875662:
 876.section .altinstructions,"a"
 877        altinstruction_entry 661b, 663f, X86_FEATURE_XMM, 662b-661b, 664f-663f
 878.previous
 879.section .altinstr_replacement,"ax"
 880663:    pushl $do_simd_coprocessor_error
 881664:
 882.previous
 883#else
 884        pushl_cfi $do_simd_coprocessor_error
 885#endif
 886        jmp error_code
 887        CFI_ENDPROC
 888END(simd_coprocessor_error)
 889
 890ENTRY(device_not_available)
 891        RING0_INT_FRAME
 892        pushl_cfi $-1                   # mark this as an int
 893        pushl_cfi $do_device_not_available
 894        jmp error_code
 895        CFI_ENDPROC
 896END(device_not_available)
 897
 898#ifdef CONFIG_PARAVIRT
 899ENTRY(native_iret)
 900        iret
 901.section __ex_table,"a"
 902        .align 4
 903        .long native_iret, iret_exc
 904.previous
 905END(native_iret)
 906
 907ENTRY(native_irq_enable_sysexit)
 908        sti
 909        sysexit
 910END(native_irq_enable_sysexit)
 911#endif
 912
 913ENTRY(overflow)
 914        RING0_INT_FRAME
 915        pushl_cfi $0
 916        pushl_cfi $do_overflow
 917        jmp error_code
 918        CFI_ENDPROC
 919END(overflow)
 920
 921ENTRY(bounds)
 922        RING0_INT_FRAME
 923        pushl_cfi $0
 924        pushl_cfi $do_bounds
 925        jmp error_code
 926        CFI_ENDPROC
 927END(bounds)
 928
 929ENTRY(invalid_op)
 930        RING0_INT_FRAME
 931        pushl_cfi $0
 932        pushl_cfi $do_invalid_op
 933        jmp error_code
 934        CFI_ENDPROC
 935END(invalid_op)
 936
 937ENTRY(coprocessor_segment_overrun)
 938        RING0_INT_FRAME
 939        pushl_cfi $0
 940        pushl_cfi $do_coprocessor_segment_overrun
 941        jmp error_code
 942        CFI_ENDPROC
 943END(coprocessor_segment_overrun)
 944
 945ENTRY(invalid_TSS)
 946        RING0_EC_FRAME
 947        pushl_cfi $do_invalid_TSS
 948        jmp error_code
 949        CFI_ENDPROC
 950END(invalid_TSS)
 951
 952ENTRY(segment_not_present)
 953        RING0_EC_FRAME
 954        pushl_cfi $do_segment_not_present
 955        jmp error_code
 956        CFI_ENDPROC
 957END(segment_not_present)
 958
 959ENTRY(stack_segment)
 960        RING0_EC_FRAME
 961        pushl_cfi $do_stack_segment
 962        jmp error_code
 963        CFI_ENDPROC
 964END(stack_segment)
 965
 966ENTRY(alignment_check)
 967        RING0_EC_FRAME
 968        pushl_cfi $do_alignment_check
 969        jmp error_code
 970        CFI_ENDPROC
 971END(alignment_check)
 972
 973ENTRY(divide_error)
 974        RING0_INT_FRAME
 975        pushl_cfi $0                    # no error code
 976        pushl_cfi $do_divide_error
 977        jmp error_code
 978        CFI_ENDPROC
 979END(divide_error)
 980
 981#ifdef CONFIG_X86_MCE
 982ENTRY(machine_check)
 983        RING0_INT_FRAME
 984        pushl_cfi $0
 985        pushl_cfi machine_check_vector
 986        jmp error_code
 987        CFI_ENDPROC
 988END(machine_check)
 989#endif
 990
 991ENTRY(spurious_interrupt_bug)
 992        RING0_INT_FRAME
 993        pushl_cfi $0
 994        pushl_cfi $do_spurious_interrupt_bug
 995        jmp error_code
 996        CFI_ENDPROC
 997END(spurious_interrupt_bug)
 998/*
 999 * End of kprobes section
1000 */
1001        .popsection
1002
1003ENTRY(kernel_thread_helper)
1004        pushl $0                # fake return address for unwinder
1005        CFI_STARTPROC
1006        movl %edi,%eax
1007        call *%esi
1008        call do_exit
1009        ud2                     # padding for call trace
1010        CFI_ENDPROC
1011ENDPROC(kernel_thread_helper)
1012
1013#ifdef CONFIG_XEN
1014/* Xen doesn't set %esp to be precisely what the normal sysenter
1015   entrypoint expects, so fix it up before using the normal path. */
1016ENTRY(xen_sysenter_target)
1017        RING0_INT_FRAME
1018        addl $5*4, %esp         /* remove xen-provided frame */
1019        CFI_ADJUST_CFA_OFFSET -5*4
1020        jmp sysenter_past_esp
1021        CFI_ENDPROC
1022
1023ENTRY(xen_hypervisor_callback)
1024        CFI_STARTPROC
1025        pushl_cfi $0
1026        SAVE_ALL
1027        TRACE_IRQS_OFF
1028
1029        /* Check to see if we got the event in the critical
1030           region in xen_iret_direct, after we've reenabled
1031           events and checked for pending events.  This simulates
1032           iret instruction's behaviour where it delivers a
1033           pending interrupt when enabling interrupts. */
1034        movl PT_EIP(%esp),%eax
1035        cmpl $xen_iret_start_crit,%eax
1036        jb   1f
1037        cmpl $xen_iret_end_crit,%eax
1038        jae  1f
1039
1040        jmp  xen_iret_crit_fixup
1041
1042ENTRY(xen_do_upcall)
10431:      mov %esp, %eax
1044        call xen_evtchn_do_upcall
1045        jmp  ret_from_intr
1046        CFI_ENDPROC
1047ENDPROC(xen_hypervisor_callback)
1048
1049# Hypervisor uses this for application faults while it executes.
1050# We get here for two reasons:
1051#  1. Fault while reloading DS, ES, FS or GS
1052#  2. Fault while executing IRET
1053# Category 1 we fix up by reattempting the load, and zeroing the segment
1054# register if the load fails.
1055# Category 2 we fix up by jumping to do_iret_error. We cannot use the
1056# normal Linux return path in this case because if we use the IRET hypercall
1057# to pop the stack frame we end up in an infinite loop of failsafe callbacks.
1058# We distinguish between categories by maintaining a status value in EAX.
1059ENTRY(xen_failsafe_callback)
1060        CFI_STARTPROC
1061        pushl_cfi %eax
1062        movl $1,%eax
10631:      mov 4(%esp),%ds
10642:      mov 8(%esp),%es
10653:      mov 12(%esp),%fs
10664:      mov 16(%esp),%gs
1067        testl %eax,%eax
1068        popl_cfi %eax
1069        lea 16(%esp),%esp
1070        CFI_ADJUST_CFA_OFFSET -16
1071        jz 5f
1072        addl $16,%esp
1073        jmp iret_exc            # EAX != 0 => Category 2 (Bad IRET)
10745:      pushl_cfi $0            # EAX == 0 => Category 1 (Bad segment)
1075        SAVE_ALL
1076        jmp ret_from_exception
1077        CFI_ENDPROC
1078
1079.section .fixup,"ax"
10806:      xorl %eax,%eax
1081        movl %eax,4(%esp)
1082        jmp 1b
10837:      xorl %eax,%eax
1084        movl %eax,8(%esp)
1085        jmp 2b
10868:      xorl %eax,%eax
1087        movl %eax,12(%esp)
1088        jmp 3b
10899:      xorl %eax,%eax
1090        movl %eax,16(%esp)
1091        jmp 4b
1092.previous
1093.section __ex_table,"a"
1094        .align 4
1095        .long 1b,6b
1096        .long 2b,7b
1097        .long 3b,8b
1098        .long 4b,9b
1099.previous
1100ENDPROC(xen_failsafe_callback)
1101
1102BUILD_INTERRUPT3(xen_hvm_callback_vector, XEN_HVM_EVTCHN_CALLBACK,
1103                xen_evtchn_do_upcall)
1104
1105#endif  /* CONFIG_XEN */
1106
1107#ifdef CONFIG_FUNCTION_TRACER
1108#ifdef CONFIG_DYNAMIC_FTRACE
1109
1110ENTRY(mcount)
1111        ret
1112END(mcount)
1113
1114ENTRY(ftrace_caller)
1115        cmpl $0, function_trace_stop
1116        jne  ftrace_stub
1117
1118        pushl %eax
1119        pushl %ecx
1120        pushl %edx
1121        movl 0xc(%esp), %eax
1122        movl 0x4(%ebp), %edx
1123        subl $MCOUNT_INSN_SIZE, %eax
1124
1125.globl ftrace_call
1126ftrace_call:
1127        call ftrace_stub
1128
1129        popl %edx
1130        popl %ecx
1131        popl %eax
1132#ifdef CONFIG_FUNCTION_GRAPH_TRACER
1133.globl ftrace_graph_call
1134ftrace_graph_call:
1135        jmp ftrace_stub
1136#endif
1137
1138.globl ftrace_stub
1139ftrace_stub:
1140        ret
1141END(ftrace_caller)
1142
1143#else /* ! CONFIG_DYNAMIC_FTRACE */
1144
1145ENTRY(mcount)
1146        cmpl $0, function_trace_stop
1147        jne  ftrace_stub
1148
1149        cmpl $ftrace_stub, ftrace_trace_function
1150        jnz trace
1151#ifdef CONFIG_FUNCTION_GRAPH_TRACER
1152        cmpl $ftrace_stub, ftrace_graph_return
1153        jnz ftrace_graph_caller
1154
1155        cmpl $ftrace_graph_entry_stub, ftrace_graph_entry
1156        jnz ftrace_graph_caller
1157#endif
1158.globl ftrace_stub
1159ftrace_stub:
1160        ret
1161
1162        /* taken from glibc */
1163trace:
1164        pushl %eax
1165        pushl %ecx
1166        pushl %edx
1167        movl 0xc(%esp), %eax
1168        movl 0x4(%ebp), %edx
1169        subl $MCOUNT_INSN_SIZE, %eax
1170
1171        call *ftrace_trace_function
1172
1173        popl %edx
1174        popl %ecx
1175        popl %eax
1176        jmp ftrace_stub
1177END(mcount)
1178#endif /* CONFIG_DYNAMIC_FTRACE */
1179#endif /* CONFIG_FUNCTION_TRACER */
1180
1181#ifdef CONFIG_FUNCTION_GRAPH_TRACER
1182ENTRY(ftrace_graph_caller)
1183        cmpl $0, function_trace_stop
1184        jne ftrace_stub
1185
1186        pushl %eax
1187        pushl %ecx
1188        pushl %edx
1189        movl 0xc(%esp), %edx
1190        lea 0x4(%ebp), %eax
1191        movl (%ebp), %ecx
1192        subl $MCOUNT_INSN_SIZE, %edx
1193        call prepare_ftrace_return
1194        popl %edx
1195        popl %ecx
1196        popl %eax
1197        ret
1198END(ftrace_graph_caller)
1199
1200.globl return_to_handler
1201return_to_handler:
1202        pushl %eax
1203        pushl %edx
1204        movl %ebp, %eax
1205        call ftrace_return_to_handler
1206        movl %eax, %ecx
1207        popl %edx
1208        popl %eax
1209        jmp *%ecx
1210#endif
1211
1212.section .rodata,"a"
1213#include "syscall_table_32.S"
1214
1215syscall_table_size=(.-sys_call_table)
1216
1217/*
1218 * Some functions should be protected against kprobes
1219 */
1220        .pushsection .kprobes.text, "ax"
1221
1222ENTRY(page_fault)
1223        RING0_EC_FRAME
1224        pushl_cfi $do_page_fault
1225        ALIGN
1226error_code:
1227        /* the function address is in %gs's slot on the stack */
1228        pushl_cfi %fs
1229        /*CFI_REL_OFFSET fs, 0*/
1230        pushl_cfi %es
1231        /*CFI_REL_OFFSET es, 0*/
1232        pushl_cfi %ds
1233        /*CFI_REL_OFFSET ds, 0*/
1234        pushl_cfi %eax
1235        CFI_REL_OFFSET eax, 0
1236        pushl_cfi %ebp
1237        CFI_REL_OFFSET ebp, 0
1238        pushl_cfi %edi
1239        CFI_REL_OFFSET edi, 0
1240        pushl_cfi %esi
1241        CFI_REL_OFFSET esi, 0
1242        pushl_cfi %edx
1243        CFI_REL_OFFSET edx, 0
1244        pushl_cfi %ecx
1245        CFI_REL_OFFSET ecx, 0
1246        pushl_cfi %ebx
1247        CFI_REL_OFFSET ebx, 0
1248        cld
1249        movl $(__KERNEL_PERCPU), %ecx
1250        movl %ecx, %fs
1251        UNWIND_ESPFIX_STACK
1252        GS_TO_REG %ecx
1253        movl PT_GS(%esp), %edi          # get the function address
1254        movl PT_ORIG_EAX(%esp), %edx    # get the error code
1255        movl $-1, PT_ORIG_EAX(%esp)     # no syscall to restart
1256        REG_TO_PTGS %ecx
1257        SET_KERNEL_GS %ecx
1258        movl $(__USER_DS), %ecx
1259        movl %ecx, %ds
1260        movl %ecx, %es
1261        TRACE_IRQS_OFF
1262        movl %esp,%eax                  # pt_regs pointer
1263        call *%edi
1264        jmp ret_from_exception
1265        CFI_ENDPROC
1266END(page_fault)
1267
1268/*
1269 * Debug traps and NMI can happen at the one SYSENTER instruction
1270 * that sets up the real kernel stack. Check here, since we can't
1271 * allow the wrong stack to be used.
1272 *
1273 * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have
1274 * already pushed 3 words if it hits on the sysenter instruction:
1275 * eflags, cs and eip.
1276 *
1277 * We just load the right stack, and push the three (known) values
1278 * by hand onto the new stack - while updating the return eip past
1279 * the instruction that would have done it for sysenter.
1280 */
1281.macro FIX_STACK offset ok label
1282        cmpw $__KERNEL_CS, 4(%esp)
1283        jne \ok
1284\label:
1285        movl TSS_sysenter_sp0 + \offset(%esp), %esp
1286        CFI_DEF_CFA esp, 0
1287        CFI_UNDEFINED eip
1288        pushfl_cfi
1289        pushl_cfi $__KERNEL_CS
1290        pushl_cfi $sysenter_past_esp
1291        CFI_REL_OFFSET eip, 0
1292.endm
1293
1294ENTRY(debug)
1295        RING0_INT_FRAME
1296        cmpl $ia32_sysenter_target,(%esp)
1297        jne debug_stack_correct
1298        FIX_STACK 12, debug_stack_correct, debug_esp_fix_insn
1299debug_stack_correct:
1300        pushl_cfi $-1                   # mark this as an int
1301        SAVE_ALL
1302        TRACE_IRQS_OFF
1303        xorl %edx,%edx                  # error code 0
1304        movl %esp,%eax                  # pt_regs pointer
1305        call do_debug
1306        jmp ret_from_exception
1307        CFI_ENDPROC
1308END(debug)
1309
1310/*
1311 * NMI is doubly nasty. It can happen _while_ we're handling
1312 * a debug fault, and the debug fault hasn't yet been able to
1313 * clear up the stack. So we first check whether we got  an
1314 * NMI on the sysenter entry path, but after that we need to
1315 * check whether we got an NMI on the debug path where the debug
1316 * fault happened on the sysenter path.
1317 */
1318ENTRY(nmi)
1319        RING0_INT_FRAME
1320        pushl_cfi %eax
1321        movl %ss, %eax
1322        cmpw $__ESPFIX_SS, %ax
1323        popl_cfi %eax
1324        je nmi_espfix_stack
1325        cmpl $ia32_sysenter_target,(%esp)
1326        je nmi_stack_fixup
1327        pushl_cfi %eax
1328        movl %esp,%eax
1329        /* Do not access memory above the end of our stack page,
1330         * it might not exist.
1331         */
1332        andl $(THREAD_SIZE-1),%eax
1333        cmpl $(THREAD_SIZE-20),%eax
1334        popl_cfi %eax
1335        jae nmi_stack_correct
1336        cmpl $ia32_sysenter_target,12(%esp)
1337        je nmi_debug_stack_check
1338nmi_stack_correct:
1339        /* We have a RING0_INT_FRAME here */
1340        pushl_cfi %eax
1341        SAVE_ALL
1342        xorl %edx,%edx          # zero error code
1343        movl %esp,%eax          # pt_regs pointer
1344        call do_nmi
1345        jmp restore_all_notrace
1346        CFI_ENDPROC
1347
1348nmi_stack_fixup:
1349        RING0_INT_FRAME
1350        FIX_STACK 12, nmi_stack_correct, 1
1351        jmp nmi_stack_correct
1352
1353nmi_debug_stack_check:
1354        /* We have a RING0_INT_FRAME here */
1355        cmpw $__KERNEL_CS,16(%esp)
1356        jne nmi_stack_correct
1357        cmpl $debug,(%esp)
1358        jb nmi_stack_correct
1359        cmpl $debug_esp_fix_insn,(%esp)
1360        ja nmi_stack_correct
1361        FIX_STACK 24, nmi_stack_correct, 1
1362        jmp nmi_stack_correct
1363
1364nmi_espfix_stack:
1365        /* We have a RING0_INT_FRAME here.
1366         *
1367         * create the pointer to lss back
1368         */
1369        pushl_cfi %ss
1370        pushl_cfi %esp
1371        addl $4, (%esp)
1372        /* copy the iret frame of 12 bytes */
1373        .rept 3
1374        pushl_cfi 16(%esp)
1375        .endr
1376        pushl_cfi %eax
1377        SAVE_ALL
1378        FIXUP_ESPFIX_STACK              # %eax == %esp
1379        xorl %edx,%edx                  # zero error code
1380        call do_nmi
1381        RESTORE_REGS
1382        lss 12+4(%esp), %esp            # back to espfix stack
1383        CFI_ADJUST_CFA_OFFSET -24
1384        jmp irq_return
1385        CFI_ENDPROC
1386END(nmi)
1387
1388ENTRY(int3)
1389        RING0_INT_FRAME
1390        pushl_cfi $-1                   # mark this as an int
1391        SAVE_ALL
1392        TRACE_IRQS_OFF
1393        xorl %edx,%edx          # zero error code
1394        movl %esp,%eax          # pt_regs pointer
1395        call do_int3
1396        jmp ret_from_exception
1397        CFI_ENDPROC
1398END(int3)
1399
1400ENTRY(general_protection)
1401        RING0_EC_FRAME
1402        pushl_cfi $do_general_protection
1403        jmp error_code
1404        CFI_ENDPROC
1405END(general_protection)
1406
1407#ifdef CONFIG_KVM_GUEST
1408ENTRY(async_page_fault)
1409        RING0_EC_FRAME
1410        pushl_cfi $do_async_page_fault
1411        jmp error_code
1412        CFI_ENDPROC
1413END(async_page_fault)
1414#endif
1415
1416/*
1417 * End of kprobes section
1418 */
1419        .popsection
1420
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