arch/x86/kernel/entry_32.S

   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) - orig_eax
  34  *      2C(%esp) - %eip
  35  *      30(%esp) - %cs
  36  *      34(%esp) - %eflags
  37  *      38(%esp) - %oldesp
  38  *      3C(%esp) - %oldss
  39  *
  40  * "current" is in register %ebx during any slow entries.
  41  */
  42
  43 #include <linux/linkage.h>
  44 #include <asm/thread_info.h>
  45 #include <asm/irqflags.h>
  46 #include <asm/errno.h>
  47 #include <asm/segment.h>
  48 #include <asm/smp.h>
  49 #include <asm/page.h>
  50 #include <asm/desc.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
  57 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
  58 #include <linux/elf-em.h>
  59 #define AUDIT_ARCH_I386         (EM_386|__AUDIT_ARCH_LE)
  60 #define __AUDIT_ARCH_LE    0x40000000
  61
  62 #ifndef CONFIG_AUDITSYSCALL
  63 #define sysenter_audit  syscall_trace_entry
  64 #define sysexit_audit   syscall_exit_work
  65 #endif
  66
  67 /*
  68  * We use macros for low-level operations which need to be overridden
  69  * for paravirtualization.  The following will never clobber any registers:
  70  *   INTERRUPT_RETURN (aka. "iret")
  71  *   GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
  72  *   ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
  73  *
  74  * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
  75  * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
  76  * Allowing a register to be clobbered can shrink the paravirt replacement
  77  * enough to patch inline, increasing performance.
  78  */
  79
  80 #define nr_syscalls ((syscall_table_size)/4)
  81
  82 #ifdef CONFIG_PREEMPT
  83 #define preempt_stop(clobbers)  DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
  84 #else
  85 #define preempt_stop(clobbers)
  86 #define resume_kernel           restore_nocheck
  87 #endif
  88
  89 .macro TRACE_IRQS_IRET
  90 #ifdef CONFIG_TRACE_IRQFLAGS
  91         testl $X86_EFLAGS_IF,PT_EFLAGS(%esp)     # interrupts off?
  92         jz 1f
  93         TRACE_IRQS_ON
  94 1:
  95 #endif
  96 .endm
  97
  98 #ifdef CONFIG_VM86
  99 #define resume_userspace_sig    check_userspace
 100 #else
 101 #define resume_userspace_sig    resume_userspace
 102 #endif
 103
 104 #define SAVE_ALL \
 105         cld; \
 106         pushl %fs; \
 107         CFI_ADJUST_CFA_OFFSET 4;\
 108         /*CFI_REL_OFFSET fs, 0;*/\
 109         pushl %es; \
 110         CFI_ADJUST_CFA_OFFSET 4;\
 111         /*CFI_REL_OFFSET es, 0;*/\
 112         pushl %ds; \
 113         CFI_ADJUST_CFA_OFFSET 4;\
 114         /*CFI_REL_OFFSET ds, 0;*/\
 115         pushl %eax; \
 116         CFI_ADJUST_CFA_OFFSET 4;\
 117         CFI_REL_OFFSET eax, 0;\
 118         pushl %ebp; \
 119         CFI_ADJUST_CFA_OFFSET 4;\
 120         CFI_REL_OFFSET ebp, 0;\
 121         pushl %edi; \
 122         CFI_ADJUST_CFA_OFFSET 4;\
 123         CFI_REL_OFFSET edi, 0;\
 124         pushl %esi; \
 125         CFI_ADJUST_CFA_OFFSET 4;\
 126         CFI_REL_OFFSET esi, 0;\
 127         pushl %edx; \
 128         CFI_ADJUST_CFA_OFFSET 4;\
 129         CFI_REL_OFFSET edx, 0;\
 130         pushl %ecx; \
 131         CFI_ADJUST_CFA_OFFSET 4;\
 132         CFI_REL_OFFSET ecx, 0;\
 133         pushl %ebx; \
 134         CFI_ADJUST_CFA_OFFSET 4;\
 135         CFI_REL_OFFSET ebx, 0;\
 136         movl $(__USER_DS), %edx; \
 137         movl %edx, %ds; \
 138         movl %edx, %es; \
 139         movl $(__KERNEL_PERCPU), %edx; \
 140         movl %edx, %fs
 141
 142 #define RESTORE_INT_REGS \
 143         popl %ebx;      \
 144         CFI_ADJUST_CFA_OFFSET -4;\
 145         CFI_RESTORE ebx;\
 146         popl %ecx;      \
 147         CFI_ADJUST_CFA_OFFSET -4;\
 148         CFI_RESTORE ecx;\
 149         popl %edx;      \
 150         CFI_ADJUST_CFA_OFFSET -4;\
 151         CFI_RESTORE edx;\
 152         popl %esi;      \
 153         CFI_ADJUST_CFA_OFFSET -4;\
 154         CFI_RESTORE esi;\
 155         popl %edi;      \
 156         CFI_ADJUST_CFA_OFFSET -4;\
 157         CFI_RESTORE edi;\
 158         popl %ebp;      \
 159         CFI_ADJUST_CFA_OFFSET -4;\
 160         CFI_RESTORE ebp;\
 161         popl %eax;      \
 162         CFI_ADJUST_CFA_OFFSET -4;\
 163         CFI_RESTORE eax
 164
 165 #define RESTORE_REGS    \
 166         RESTORE_INT_REGS; \
 167 1:      popl %ds;       \
 168         CFI_ADJUST_CFA_OFFSET -4;\
 169         /*CFI_RESTORE ds;*/\
 170 2:      popl %es;       \
 171         CFI_ADJUST_CFA_OFFSET -4;\
 172         /*CFI_RESTORE es;*/\
 173 3:      popl %fs;       \
 174         CFI_ADJUST_CFA_OFFSET -4;\
 175         /*CFI_RESTORE fs;*/\
 176 .pushsection .fixup,"ax";       \
 177 4:      movl $0,(%esp); \
 178         jmp 1b;         \
 179 5:      movl $0,(%esp); \
 180         jmp 2b;         \
 181 6:      movl $0,(%esp); \
 182         jmp 3b;         \
 183 .section __ex_table,"a";\
 184         .align 4;       \
 185         .long 1b,4b;    \
 186         .long 2b,5b;    \
 187         .long 3b,6b;    \
 188 .popsection
 189
 190 #define RING0_INT_FRAME \
 191         CFI_STARTPROC simple;\
 192         CFI_SIGNAL_FRAME;\
 193         CFI_DEF_CFA esp, 3*4;\
 194         /*CFI_OFFSET cs, -2*4;*/\
 195         CFI_OFFSET eip, -3*4
 196
 197 #define RING0_EC_FRAME \
 198         CFI_STARTPROC simple;\
 199         CFI_SIGNAL_FRAME;\
 200         CFI_DEF_CFA esp, 4*4;\
 201         /*CFI_OFFSET cs, -2*4;*/\
 202         CFI_OFFSET eip, -3*4
 203
 204 #define RING0_PTREGS_FRAME \
 205         CFI_STARTPROC simple;\
 206         CFI_SIGNAL_FRAME;\
 207         CFI_DEF_CFA esp, PT_OLDESP-PT_EBX;\
 208         /*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/\
 209         CFI_OFFSET eip, PT_EIP-PT_OLDESP;\
 210         /*CFI_OFFSET es, PT_ES-PT_OLDESP;*/\
 211         /*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/\
 212         CFI_OFFSET eax, PT_EAX-PT_OLDESP;\
 213         CFI_OFFSET ebp, PT_EBP-PT_OLDESP;\
 214         CFI_OFFSET edi, PT_EDI-PT_OLDESP;\
 215         CFI_OFFSET esi, PT_ESI-PT_OLDESP;\
 216         CFI_OFFSET edx, PT_EDX-PT_OLDESP;\
 217         CFI_OFFSET ecx, PT_ECX-PT_OLDESP;\
 218         CFI_OFFSET ebx, PT_EBX-PT_OLDESP
 219
 220 ENTRY(ret_from_fork)
 221         CFI_STARTPROC
 222         pushl %eax
 223         CFI_ADJUST_CFA_OFFSET 4
 224         call schedule_tail
 225         GET_THREAD_INFO(%ebp)
 226         popl %eax
 227         CFI_ADJUST_CFA_OFFSET -4
 228         pushl $0x0202                   # Reset kernel eflags
 229         CFI_ADJUST_CFA_OFFSET 4
 230         popfl
 231         CFI_ADJUST_CFA_OFFSET -4
 232         jmp syscall_exit
 233         CFI_ENDPROC
 234 END(ret_from_fork)
 235
 236 /*
 237  * Return to user mode is not as complex as all this looks,
 238  * but we want the default path for a system call return to
 239  * go as quickly as possible which is why some of this is
 240  * less clear than it otherwise should be.
 241  */
 242
 243         # userspace resumption stub bypassing syscall exit tracing
 244         ALIGN
 245         RING0_PTREGS_FRAME
 246 ret_from_exception:
 247         preempt_stop(CLBR_ANY)
 248 ret_from_intr:
 249         GET_THREAD_INFO(%ebp)
 250 check_userspace:
 251         movl PT_EFLAGS(%esp), %eax      # mix EFLAGS and CS
 252         movb PT_CS(%esp), %al
 253         andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
 254         cmpl $USER_RPL, %eax
 255         jb resume_kernel                # not returning to v8086 or userspace
 256
 257 ENTRY(resume_userspace)
 258         LOCKDEP_SYS_EXIT
 259         DISABLE_INTERRUPTS(CLBR_ANY)    # make sure we don't miss an interrupt
 260                                         # setting need_resched or sigpending
 261                                         # between sampling and the iret
 262         TRACE_IRQS_OFF
 263         movl TI_flags(%ebp), %ecx
 264         andl $_TIF_WORK_MASK, %ecx      # is there any work to be done on
 265                                         # int/exception return?
 266         jne work_pending
 267         jmp restore_all
 268 END(ret_from_exception)
 269
 270 #ifdef CONFIG_PREEMPT
 271 ENTRY(resume_kernel)
 272         DISABLE_INTERRUPTS(CLBR_ANY)
 273         cmpl $0,TI_preempt_count(%ebp)  # non-zero preempt_count ?
 274         jnz restore_nocheck
 275 need_resched:
 276         movl TI_flags(%ebp), %ecx       # need_resched set ?
 277         testb $_TIF_NEED_RESCHED, %cl
 278         jz restore_all
 279         testl $X86_EFLAGS_IF,PT_EFLAGS(%esp)    # interrupts off (exception path) ?
 280         jz restore_all
 281         call preempt_schedule_irq
 282         jmp need_resched
 283 END(resume_kernel)
 284 #endif
 285         CFI_ENDPROC
 286
 287 /* SYSENTER_RETURN points to after the "sysenter" instruction in
 288    the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */
 289
 290         # sysenter call handler stub
 291 ENTRY(ia32_sysenter_target)
 292         CFI_STARTPROC simple
 293         CFI_SIGNAL_FRAME
 294         CFI_DEF_CFA esp, 0
 295         CFI_REGISTER esp, ebp
 296         movl TSS_sysenter_sp0(%esp),%esp
 297 sysenter_past_esp:
 298         /*
 299          * Interrupts are disabled here, but we can't trace it until
 300          * enough kernel state to call TRACE_IRQS_OFF can be called - but
 301          * we immediately enable interrupts at that point anyway.
 302          */
 303         pushl $(__USER_DS)
 304         CFI_ADJUST_CFA_OFFSET 4
 305         /*CFI_REL_OFFSET ss, 0*/
 306         pushl %ebp
 307         CFI_ADJUST_CFA_OFFSET 4
 308         CFI_REL_OFFSET esp, 0
 309         pushfl
 310         orl $X86_EFLAGS_IF, (%esp)
 311         CFI_ADJUST_CFA_OFFSET 4
 312         pushl $(__USER_CS)
 313         CFI_ADJUST_CFA_OFFSET 4
 314         /*CFI_REL_OFFSET cs, 0*/
 315         /*
 316          * Push current_thread_info()->sysenter_return to the stack.
 317          * A tiny bit of offset fixup is necessary - 4*4 means the 4 words
 318          * pushed above; +8 corresponds to copy_thread's esp0 setting.
 319          */
 320         pushl (TI_sysenter_return-THREAD_SIZE+8+4*4)(%esp)
 321         CFI_ADJUST_CFA_OFFSET 4
 322         CFI_REL_OFFSET eip, 0
 323
 324         pushl %eax
 325         CFI_ADJUST_CFA_OFFSET 4
 326         SAVE_ALL
 327         ENABLE_INTERRUPTS(CLBR_NONE)
 328
 329 /*
 330  * Load the potential sixth argument from user stack.
 331  * Careful about security.
 332  */
 333         cmpl $__PAGE_OFFSET-3,%ebp
 334         jae syscall_fault
 335 1:      movl (%ebp),%ebp
 336         movl %ebp,PT_EBP(%esp)
 337 .section __ex_table,"a"
 338         .align 4
 339         .long 1b,syscall_fault
 340 .previous
 341
 342         GET_THREAD_INFO(%ebp)
 343
 344         /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
 345         testw $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
 346         jnz sysenter_audit
 347 sysenter_do_call:
 348         cmpl $(nr_syscalls), %eax
 349         jae syscall_badsys
 350         call *sys_call_table(,%eax,4)
 351         movl %eax,PT_EAX(%esp)
 352         LOCKDEP_SYS_EXIT
 353         DISABLE_INTERRUPTS(CLBR_ANY)
 354         TRACE_IRQS_OFF
 355         movl TI_flags(%ebp), %ecx
 356         testw $_TIF_ALLWORK_MASK, %cx
 357         jne sysexit_audit
 358 sysenter_exit:
 359 /* if something modifies registers it must also disable sysexit */
 360         movl PT_EIP(%esp), %edx
 361         movl PT_OLDESP(%esp), %ecx
 362         xorl %ebp,%ebp
 363         TRACE_IRQS_ON
 364 1:      mov  PT_FS(%esp), %fs
 365         ENABLE_INTERRUPTS_SYSEXIT
 366
 367 #ifdef CONFIG_AUDITSYSCALL
 368 sysenter_audit:
 369         testw $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
 370         jnz syscall_trace_entry
 371         addl $4,%esp
 372         CFI_ADJUST_CFA_OFFSET -4
 373         /* %esi already in 8(%esp)         6th arg: 4th syscall arg */
 374         /* %edx already in 4(%esp)         5th arg: 3rd syscall arg */
 375         /* %ecx already in 0(%esp)         4th arg: 2nd syscall arg */
 376         movl %ebx,%ecx                  /* 3rd arg: 1st syscall arg */
 377         movl %eax,%edx                  /* 2nd arg: syscall number */
 378         movl $AUDIT_ARCH_I386,%eax      /* 1st arg: audit arch */
 379         call audit_syscall_entry
 380         pushl %ebx
 381         CFI_ADJUST_CFA_OFFSET 4
 382         movl PT_EAX(%esp),%eax          /* reload syscall number */
 383         jmp sysenter_do_call
 384
 385 sysexit_audit:
 386         testw $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %cx
 387         jne syscall_exit_work
 388         TRACE_IRQS_ON
 389         ENABLE_INTERRUPTS(CLBR_ANY)
 390         movl %eax,%edx          /* second arg, syscall return value */
 391         cmpl $0,%eax            /* is it < 0? */
 392         setl %al                /* 1 if so, 0 if not */
 393         movzbl %al,%eax         /* zero-extend that */
 394         inc %eax /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
 395         call audit_syscall_exit
 396         DISABLE_INTERRUPTS(CLBR_ANY)
 397         TRACE_IRQS_OFF
 398         movl TI_flags(%ebp), %ecx
 399         testw $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %cx
 400         jne syscall_exit_work
 401         movl PT_EAX(%esp),%eax  /* reload syscall return value */
 402         jmp sysenter_exit
 403 #endif
 404
 405         CFI_ENDPROC
 406 .pushsection .fixup,"ax"
 407 2:      movl $0,PT_FS(%esp)
 408         jmp 1b
 409 .section __ex_table,"a"
 410         .align 4
 411         .long 1b,2b
 412 .popsection
 413 ENDPROC(ia32_sysenter_target)
 414
 415         # system call handler stub
 416 ENTRY(system_call)
 417         RING0_INT_FRAME                 # can't unwind into user space anyway
 418         pushl %eax                      # save orig_eax
 419         CFI_ADJUST_CFA_OFFSET 4
 420         SAVE_ALL
 421         GET_THREAD_INFO(%ebp)
 422                                         # system call tracing in operation / emulation
 423         /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
 424         testw $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
 425         jnz syscall_trace_entry
 426         cmpl $(nr_syscalls), %eax
 427         jae syscall_badsys
 428 syscall_call:
 429         call *sys_call_table(,%eax,4)
 430         movl %eax,PT_EAX(%esp)          # store the return value
 431 syscall_exit:
 432         LOCKDEP_SYS_EXIT
 433         DISABLE_INTERRUPTS(CLBR_ANY)    # make sure we don't miss an interrupt
 434                                         # setting need_resched or sigpending
 435                                         # between sampling and the iret
 436         TRACE_IRQS_OFF
 437         movl TI_flags(%ebp), %ecx
 438         testw $_TIF_ALLWORK_MASK, %cx   # current->work
 439         jne syscall_exit_work
 440
 441 restore_all:
 442         movl PT_EFLAGS(%esp), %eax      # mix EFLAGS, SS and CS
 443         # Warning: PT_OLDSS(%esp) contains the wrong/random values if we
 444         # are returning to the kernel.
 445         # See comments in process.c:copy_thread() for details.
 446         movb PT_OLDSS(%esp), %ah
 447         movb PT_CS(%esp), %al
 448         andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
 449         cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax
 450         CFI_REMEMBER_STATE
 451         je ldt_ss                       # returning to user-space with LDT SS
 452 restore_nocheck:
 453         TRACE_IRQS_IRET
 454 restore_nocheck_notrace:
 455         RESTORE_REGS
 456         addl $4, %esp                   # skip orig_eax/error_code
 457         CFI_ADJUST_CFA_OFFSET -4
 458 irq_return:
 459         INTERRUPT_RETURN
 460 .section .fixup,"ax"
 461 ENTRY(iret_exc)
 462         pushl $0                        # no error code
 463         pushl $do_iret_error
 464         jmp error_code
 465 .previous
 466 .section __ex_table,"a"
 467         .align 4
 468         .long irq_return,iret_exc
 469 .previous
 470
 471         CFI_RESTORE_STATE
 472 ldt_ss:
 473         larl PT_OLDSS(%esp), %eax
 474         jnz restore_nocheck
 475         testl $0x00400000, %eax         # returning to 32bit stack?
 476         jnz restore_nocheck             # allright, normal return
 477
 478 #ifdef CONFIG_PARAVIRT
 479         /*
 480          * The kernel can't run on a non-flat stack if paravirt mode
 481          * is active.  Rather than try to fixup the high bits of
 482          * ESP, bypass this code entirely.  This may break DOSemu
 483          * and/or Wine support in a paravirt VM, although the option
 484          * is still available to implement the setting of the high
 485          * 16-bits in the INTERRUPT_RETURN paravirt-op.
 486          */
 487         cmpl $0, pv_info+PARAVIRT_enabled
 488         jne restore_nocheck
 489 #endif
 490
 491         /* If returning to userspace with 16bit stack,
 492          * try to fix the higher word of ESP, as the CPU
 493          * won't restore it.
 494          * This is an "official" bug of all the x86-compatible
 495          * CPUs, which we can try to work around to make
 496          * dosemu and wine happy. */
 497         movl PT_OLDESP(%esp), %eax
 498         movl %esp, %edx
 499         call patch_espfix_desc
 500         pushl $__ESPFIX_SS
 501         CFI_ADJUST_CFA_OFFSET 4
 502         pushl %eax
 503         CFI_ADJUST_CFA_OFFSET 4
 504         DISABLE_INTERRUPTS(CLBR_EAX)
 505         TRACE_IRQS_OFF
 506         lss (%esp), %esp
 507         CFI_ADJUST_CFA_OFFSET -8
 508         jmp restore_nocheck
 509         CFI_ENDPROC
 510 ENDPROC(system_call)
 511
 512         # perform work that needs to be done immediately before resumption
 513         ALIGN
 514         RING0_PTREGS_FRAME              # can't unwind into user space anyway
 515 work_pending:
 516         testb $_TIF_NEED_RESCHED, %cl
 517         jz work_notifysig
 518 work_resched:
 519         call schedule
 520         LOCKDEP_SYS_EXIT
 521         DISABLE_INTERRUPTS(CLBR_ANY)    # make sure we don't miss an interrupt
 522                                         # setting need_resched or sigpending
 523                                         # between sampling and the iret
 524         TRACE_IRQS_OFF
 525         movl TI_flags(%ebp), %ecx
 526         andl $_TIF_WORK_MASK, %ecx      # is there any work to be done other
 527                                         # than syscall tracing?
 528         jz restore_all
 529         testb $_TIF_NEED_RESCHED, %cl
 530         jnz work_resched
 531
 532 work_notifysig:                         # deal with pending signals and
 533                                         # notify-resume requests
 534 #ifdef CONFIG_VM86
 535         testl $X86_EFLAGS_VM, PT_EFLAGS(%esp)
 536         movl %esp, %eax
 537         jne work_notifysig_v86          # returning to kernel-space or
 538                                         # vm86-space
 539         xorl %edx, %edx
 540         call do_notify_resume
 541         jmp resume_userspace_sig
 542
 543         ALIGN
 544 work_notifysig_v86:
 545         pushl %ecx                      # save ti_flags for do_notify_resume
 546         CFI_ADJUST_CFA_OFFSET 4
 547         call save_v86_state             # %eax contains pt_regs pointer
 548         popl %ecx
 549         CFI_ADJUST_CFA_OFFSET -4
 550         movl %eax, %esp
 551 #else
 552         movl %esp, %eax
 553 #endif
 554         xorl %edx, %edx
 555         call do_notify_resume
 556         jmp resume_userspace_sig
 557 END(work_pending)
 558
 559         # perform syscall exit tracing
 560         ALIGN
 561 syscall_trace_entry:
 562         movl $-ENOSYS,PT_EAX(%esp)
 563         movl %esp, %eax
 564         call syscall_trace_enter
 565         /* What it returned is what we'll actually use.  */
 566         cmpl $(nr_syscalls), %eax
 567         jnae syscall_call
 568         jmp syscall_exit
 569 END(syscall_trace_entry)
 570
 571         # perform syscall exit tracing
 572         ALIGN
 573 syscall_exit_work:
 574         testb $_TIF_WORK_SYSCALL_EXIT, %cl
 575         jz work_pending
 576         TRACE_IRQS_ON
 577         ENABLE_INTERRUPTS(CLBR_ANY)     # could let syscall_trace_leave() call
 578                                         # schedule() instead
 579         movl %esp, %eax
 580         call syscall_trace_leave
 581         jmp resume_userspace
 582 END(syscall_exit_work)
 583         CFI_ENDPROC
 584
 585         RING0_INT_FRAME                 # can't unwind into user space anyway
 586 syscall_fault:
 587         GET_THREAD_INFO(%ebp)
 588         movl $-EFAULT,PT_EAX(%esp)
 589         jmp resume_userspace
 590 END(syscall_fault)
 591
 592 syscall_badsys:
 593         movl $-ENOSYS,PT_EAX(%esp)
 594         jmp resume_userspace
 595 END(syscall_badsys)
 596         CFI_ENDPROC
 597
 598 #define FIXUP_ESPFIX_STACK \
 599         /* since we are on a wrong stack, we cant make it a C code :( */ \
 600         PER_CPU(gdt_page, %ebx); \
 601         GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \
 602         addl %esp, %eax; \
 603         pushl $__KERNEL_DS; \
 604         CFI_ADJUST_CFA_OFFSET 4; \
 605         pushl %eax; \
 606         CFI_ADJUST_CFA_OFFSET 4; \
 607         lss (%esp), %esp; \
 608         CFI_ADJUST_CFA_OFFSET -8;
 609 #define UNWIND_ESPFIX_STACK \
 610         movl %ss, %eax; \
 611         /* see if on espfix stack */ \
 612         cmpw $__ESPFIX_SS, %ax; \
 613         jne 27f; \
 614         movl $__KERNEL_DS, %eax; \
 615         movl %eax, %ds; \
 616         movl %eax, %es; \
 617         /* switch to normal stack */ \
 618         FIXUP_ESPFIX_STACK; \
 619 27:;
 620
 621 /*
 622  * Build the entry stubs and pointer table with some assembler magic.
 623  * We pack 7 stubs into a single 32-byte chunk, which will fit in a
 624  * single cache line on all modern x86 implementations.
 625  */
 626 .section .init.rodata,"a"
 627 ENTRY(interrupt)
 628 .text
 629         .p2align 5
 630         .p2align CONFIG_X86_L1_CACHE_SHIFT
 631 ENTRY(irq_entries_start)
 632         RING0_INT_FRAME
 633 vector=FIRST_EXTERNAL_VECTOR
 634 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
 635         .balign 32
 636   .rept 7
 637     .if vector < NR_VECTORS
 638       .if vector <> FIRST_EXTERNAL_VECTOR
 639         CFI_ADJUST_CFA_OFFSET -4
 640       .endif
 641 1:      pushl $(~vector+0x80)   /* Note: always in signed byte range */
 642         CFI_ADJUST_CFA_OFFSET 4
 643       .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
 644         jmp 2f
 645       .endif
 646       .previous
 647         .long 1b
 648       .text
 649 vector=vector+1
 650     .endif
 651   .endr
 652 2:      jmp common_interrupt
 653 .endr
 654 END(irq_entries_start)
 655
 656 .previous
 657 END(interrupt)
 658 .previous
 659
 660 /*
 661  * the CPU automatically disables interrupts when executing an IRQ vector,
 662  * so IRQ-flags tracing has to follow that:
 663  */
 664         .p2align CONFIG_X86_L1_CACHE_SHIFT
 665 common_interrupt:
 666         addl $-0x80,(%esp)      /* Adjust vector into the [-256,-1] range */
 667         SAVE_ALL
 668         TRACE_IRQS_OFF
 669         movl %esp,%eax
 670         call do_IRQ
 671         jmp ret_from_intr
 672 ENDPROC(common_interrupt)
 673         CFI_ENDPROC
 674
 675 #define BUILD_INTERRUPT(name, nr)       \
 676 ENTRY(name)                             \
 677         RING0_INT_FRAME;                \
 678         pushl $~(nr);                   \
 679         CFI_ADJUST_CFA_OFFSET 4;        \
 680         SAVE_ALL;                       \
 681         TRACE_IRQS_OFF                  \
 682         movl %esp,%eax;                 \
 683         call smp_##name;                \
 684         jmp ret_from_intr;              \
 685         CFI_ENDPROC;                    \
 686 ENDPROC(name)
 687
 688 /* The include is where all of the SMP etc. interrupts come from */
 689 #include "entry_arch.h"
 690
 691 ENTRY(coprocessor_error)
 692         RING0_INT_FRAME
 693         pushl $0
 694         CFI_ADJUST_CFA_OFFSET 4
 695         pushl $do_coprocessor_error
 696         CFI_ADJUST_CFA_OFFSET 4
 697         jmp error_code
 698         CFI_ENDPROC
 699 END(coprocessor_error)
 700
 701 ENTRY(simd_coprocessor_error)
 702         RING0_INT_FRAME
 703         pushl $0
 704         CFI_ADJUST_CFA_OFFSET 4
 705         pushl $do_simd_coprocessor_error
 706         CFI_ADJUST_CFA_OFFSET 4
 707         jmp error_code
 708         CFI_ENDPROC
 709 END(simd_coprocessor_error)
 710
 711 ENTRY(device_not_available)
 712         RING0_INT_FRAME
 713         pushl $-1                       # mark this as an int
 714         CFI_ADJUST_CFA_OFFSET 4
 715         pushl $do_device_not_available
 716         CFI_ADJUST_CFA_OFFSET 4
 717         jmp error_code
 718         CFI_ENDPROC
 719 END(device_not_available)
 720
 721 #ifdef CONFIG_PARAVIRT
 722 ENTRY(native_iret)
 723         iret
 724 .section __ex_table,"a"
 725         .align 4
 726         .long native_iret, iret_exc
 727 .previous
 728 END(native_iret)
 729
 730 ENTRY(native_irq_enable_sysexit)
 731         sti
 732         sysexit
 733 END(native_irq_enable_sysexit)
 734 #endif
 735
 736 ENTRY(overflow)
 737         RING0_INT_FRAME
 738         pushl $0
 739         CFI_ADJUST_CFA_OFFSET 4
 740         pushl $do_overflow
 741         CFI_ADJUST_CFA_OFFSET 4
 742         jmp error_code
 743         CFI_ENDPROC
 744 END(overflow)
 745
 746 ENTRY(bounds)
 747         RING0_INT_FRAME
 748         pushl $0
 749         CFI_ADJUST_CFA_OFFSET 4
 750         pushl $do_bounds
 751         CFI_ADJUST_CFA_OFFSET 4
 752         jmp error_code
 753         CFI_ENDPROC
 754 END(bounds)
 755
 756 ENTRY(invalid_op)
 757         RING0_INT_FRAME
 758         pushl $0
 759         CFI_ADJUST_CFA_OFFSET 4
 760         pushl $do_invalid_op
 761         CFI_ADJUST_CFA_OFFSET 4
 762         jmp error_code
 763         CFI_ENDPROC
 764 END(invalid_op)
 765
 766 ENTRY(coprocessor_segment_overrun)
 767         RING0_INT_FRAME
 768         pushl $0
 769         CFI_ADJUST_CFA_OFFSET 4
 770         pushl $do_coprocessor_segment_overrun
 771         CFI_ADJUST_CFA_OFFSET 4
 772         jmp error_code
 773         CFI_ENDPROC
 774 END(coprocessor_segment_overrun)
 775
 776 ENTRY(invalid_TSS)
 777         RING0_EC_FRAME
 778         pushl $do_invalid_TSS
 779         CFI_ADJUST_CFA_OFFSET 4
 780         jmp error_code
 781         CFI_ENDPROC
 782 END(invalid_TSS)
 783
 784 ENTRY(segment_not_present)
 785         RING0_EC_FRAME
 786         pushl $do_segment_not_present
 787         CFI_ADJUST_CFA_OFFSET 4
 788         jmp error_code
 789         CFI_ENDPROC
 790 END(segment_not_present)
 791
 792 ENTRY(stack_segment)
 793         RING0_EC_FRAME
 794         pushl $do_stack_segment
 795         CFI_ADJUST_CFA_OFFSET 4
 796         jmp error_code
 797         CFI_ENDPROC
 798 END(stack_segment)
 799
 800 ENTRY(alignment_check)
 801         RING0_EC_FRAME
 802         pushl $do_alignment_check
 803         CFI_ADJUST_CFA_OFFSET 4
 804         jmp error_code
 805         CFI_ENDPROC
 806 END(alignment_check)
 807
 808 ENTRY(divide_error)
 809         RING0_INT_FRAME
 810         pushl $0                        # no error code
 811         CFI_ADJUST_CFA_OFFSET 4
 812         pushl $do_divide_error
 813         CFI_ADJUST_CFA_OFFSET 4
 814         jmp error_code
 815         CFI_ENDPROC
 816 END(divide_error)
 817
 818 #ifdef CONFIG_X86_MCE
 819 ENTRY(machine_check)
 820         RING0_INT_FRAME
 821         pushl $0
 822         CFI_ADJUST_CFA_OFFSET 4
 823         pushl machine_check_vector
 824         CFI_ADJUST_CFA_OFFSET 4
 825         jmp error_code
 826         CFI_ENDPROC
 827 END(machine_check)
 828 #endif
 829
 830 ENTRY(spurious_interrupt_bug)
 831         RING0_INT_FRAME
 832         pushl $0
 833         CFI_ADJUST_CFA_OFFSET 4
 834         pushl $do_spurious_interrupt_bug
 835         CFI_ADJUST_CFA_OFFSET 4
 836         jmp error_code
 837         CFI_ENDPROC
 838 END(spurious_interrupt_bug)
 839
 840 ENTRY(kernel_thread_helper)
 841         pushl $0                # fake return address for unwinder
 842         CFI_STARTPROC
 843         movl %edx,%eax
 844         push %edx
 845         CFI_ADJUST_CFA_OFFSET 4
 846         call *%ebx
 847         push %eax
 848         CFI_ADJUST_CFA_OFFSET 4
 849         call do_exit
 850         ud2                     # padding for call trace
 851         CFI_ENDPROC
 852 ENDPROC(kernel_thread_helper)
 853
 854 #ifdef CONFIG_XEN
 855 /* Xen doesn't set %esp to be precisely what the normal sysenter
 856    entrypoint expects, so fix it up before using the normal path. */
 857 ENTRY(xen_sysenter_target)
 858         RING0_INT_FRAME
 859         addl $5*4, %esp         /* remove xen-provided frame */
 860         CFI_ADJUST_CFA_OFFSET -5*4
 861         jmp sysenter_past_esp
 862         CFI_ENDPROC
 863
 864 ENTRY(xen_hypervisor_callback)
 865         CFI_STARTPROC
 866         pushl $0
 867         CFI_ADJUST_CFA_OFFSET 4
 868         SAVE_ALL
 869         TRACE_IRQS_OFF
 870
 871         /* Check to see if we got the event in the critical
 872            region in xen_iret_direct, after we've reenabled
 873            events and checked for pending events.  This simulates
 874            iret instruction's behaviour where it delivers a
 875            pending interrupt when enabling interrupts. */
 876         movl PT_EIP(%esp),%eax
 877         cmpl $xen_iret_start_crit,%eax
 878         jb   1f
 879         cmpl $xen_iret_end_crit,%eax
 880         jae  1f
 881
 882         jmp  xen_iret_crit_fixup
 883
 884 ENTRY(xen_do_upcall)
 885 1:      mov %esp, %eax
 886         call xen_evtchn_do_upcall
 887         jmp  ret_from_intr
 888         CFI_ENDPROC
 889 ENDPROC(xen_hypervisor_callback)
 890
 891 # Hypervisor uses this for application faults while it executes.
 892 # We get here for two reasons:
 893 #  1. Fault while reloading DS, ES, FS or GS
 894 #  2. Fault while executing IRET
 895 # Category 1 we fix up by reattempting the load, and zeroing the segment
 896 # register if the load fails.
 897 # Category 2 we fix up by jumping to do_iret_error. We cannot use the
 898 # normal Linux return path in this case because if we use the IRET hypercall
 899 # to pop the stack frame we end up in an infinite loop of failsafe callbacks.
 900 # We distinguish between categories by maintaining a status value in EAX.
 901 ENTRY(xen_failsafe_callback)
 902         CFI_STARTPROC
 903         pushl %eax
 904         CFI_ADJUST_CFA_OFFSET 4
 905         movl $1,%eax
 906 1:      mov 4(%esp),%ds
 907 2:      mov 8(%esp),%es
 908 3:      mov 12(%esp),%fs
 909 4:      mov 16(%esp),%gs
 910         testl %eax,%eax
 911         popl %eax
 912         CFI_ADJUST_CFA_OFFSET -4
 913         lea 16(%esp),%esp
 914         CFI_ADJUST_CFA_OFFSET -16
 915         jz 5f
 916         addl $16,%esp
 917         jmp iret_exc            # EAX != 0 => Category 2 (Bad IRET)
 918 5:      pushl $0                # EAX == 0 => Category 1 (Bad segment)
 919         CFI_ADJUST_CFA_OFFSET 4
 920         SAVE_ALL
 921         jmp ret_from_exception
 922         CFI_ENDPROC
 923
 924 .section .fixup,"ax"
 925 6:      xorl %eax,%eax
 926         movl %eax,4(%esp)
 927         jmp 1b
 928 7:      xorl %eax,%eax
 929         movl %eax,8(%esp)
 930         jmp 2b
 931 8:      xorl %eax,%eax
 932         movl %eax,12(%esp)
 933         jmp 3b
 934 9:      xorl %eax,%eax
 935         movl %eax,16(%esp)
 936         jmp 4b
 937 .previous
 938 .section __ex_table,"a"
 939         .align 4
 940         .long 1b,6b
 941         .long 2b,7b
 942         .long 3b,8b
 943         .long 4b,9b
 944 .previous
 945 ENDPROC(xen_failsafe_callback)
 946
 947 #endif  /* CONFIG_XEN */
 948
 949 #ifdef CONFIG_FUNCTION_TRACER
 950 #ifdef CONFIG_DYNAMIC_FTRACE
 951
 952 ENTRY(mcount)
 953         ret
 954 END(mcount)
 955
 956 ENTRY(ftrace_caller)
 957         pushl %eax
 958         pushl %ecx
 959         pushl %edx
 960         movl 0xc(%esp), %eax
 961         movl 0x4(%ebp), %edx
 962         subl $MCOUNT_INSN_SIZE, %eax
 963
 964 .globl ftrace_call
 965 ftrace_call:
 966         call ftrace_stub
 967
 968         popl %edx
 969         popl %ecx
 970         popl %eax
 971
 972 .globl ftrace_stub
 973 ftrace_stub:
 974         ret
 975 END(ftrace_caller)
 976
 977 #else /* ! CONFIG_DYNAMIC_FTRACE */
 978
 979 ENTRY(mcount)
 980         cmpl $ftrace_stub, ftrace_trace_function
 981         jnz trace
 982 .globl ftrace_stub
 983 ftrace_stub:
 984         ret
 985
 986         /* taken from glibc */
 987 trace:
 988         pushl %eax
 989         pushl %ecx
 990         pushl %edx
 991         movl 0xc(%esp), %eax
 992         movl 0x4(%ebp), %edx
 993         subl $MCOUNT_INSN_SIZE, %eax
 994
 995         call *ftrace_trace_function
 996
 997         popl %edx
 998         popl %ecx
 999         popl %eax
1000
1001         jmp ftrace_stub
1002 END(mcount)
1003 #endif /* CONFIG_DYNAMIC_FTRACE */
1004 #endif /* CONFIG_FUNCTION_TRACER */
1005
1006 .section .rodata,"a"
1007 #include "syscall_table_32.S"
1008
1009 syscall_table_size=(.-sys_call_table)
1010
1011 /*
1012  * Some functions should be protected against kprobes
1013  */
1014         .pushsection .kprobes.text, "ax"
1015
1016 ENTRY(page_fault)
1017         RING0_EC_FRAME
1018         pushl $do_page_fault
1019         CFI_ADJUST_CFA_OFFSET 4
1020         ALIGN
1021 error_code:
1022         /* the function address is in %fs's slot on the stack */
1023         pushl %es
1024         CFI_ADJUST_CFA_OFFSET 4
1025         /*CFI_REL_OFFSET es, 0*/
1026         pushl %ds
1027         CFI_ADJUST_CFA_OFFSET 4
1028         /*CFI_REL_OFFSET ds, 0*/
1029         pushl %eax
1030         CFI_ADJUST_CFA_OFFSET 4
1031         CFI_REL_OFFSET eax, 0
1032         pushl %ebp
1033         CFI_ADJUST_CFA_OFFSET 4
1034         CFI_REL_OFFSET ebp, 0
1035         pushl %edi
1036         CFI_ADJUST_CFA_OFFSET 4
1037         CFI_REL_OFFSET edi, 0
1038         pushl %esi
1039         CFI_ADJUST_CFA_OFFSET 4
1040         CFI_REL_OFFSET esi, 0
1041         pushl %edx
1042         CFI_ADJUST_CFA_OFFSET 4
1043         CFI_REL_OFFSET edx, 0
1044         pushl %ecx
1045         CFI_ADJUST_CFA_OFFSET 4
1046         CFI_REL_OFFSET ecx, 0
1047         pushl %ebx
1048         CFI_ADJUST_CFA_OFFSET 4
1049         CFI_REL_OFFSET ebx, 0
1050         cld
1051         pushl %fs
1052         CFI_ADJUST_CFA_OFFSET 4
1053         /*CFI_REL_OFFSET fs, 0*/
1054         movl $(__KERNEL_PERCPU), %ecx
1055         movl %ecx, %fs
1056         UNWIND_ESPFIX_STACK
1057         popl %ecx
1058         CFI_ADJUST_CFA_OFFSET -4
1059         /*CFI_REGISTER es, ecx*/
1060         movl PT_FS(%esp), %edi          # get the function address
1061         movl PT_ORIG_EAX(%esp), %edx    # get the error code
1062         movl $-1, PT_ORIG_EAX(%esp)     # no syscall to restart
1063         mov  %ecx, PT_FS(%esp)
1064         /*CFI_REL_OFFSET fs, ES*/
1065         movl $(__USER_DS), %ecx
1066         movl %ecx, %ds
1067         movl %ecx, %es
1068         TRACE_IRQS_OFF
1069         movl %esp,%eax                  # pt_regs pointer
1070         call *%edi
1071         jmp ret_from_exception
1072         CFI_ENDPROC
1073 END(page_fault)
1074
1075 /*
1076  * Debug traps and NMI can happen at the one SYSENTER instruction
1077  * that sets up the real kernel stack. Check here, since we can't
1078  * allow the wrong stack to be used.
1079  *
1080  * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have
1081  * already pushed 3 words if it hits on the sysenter instruction:
1082  * eflags, cs and eip.
1083  *
1084  * We just load the right stack, and push the three (known) values
1085  * by hand onto the new stack - while updating the return eip past
1086  * the instruction that would have done it for sysenter.
1087  */
1088 #define FIX_STACK(offset, ok, label)            \
1089         cmpw $__KERNEL_CS,4(%esp);              \
1090         jne ok;                                 \
1091 label:                                          \
1092         movl TSS_sysenter_sp0+offset(%esp),%esp;        \
1093         CFI_DEF_CFA esp, 0;                     \
1094         CFI_UNDEFINED eip;                      \
1095         pushfl;                                 \
1096         CFI_ADJUST_CFA_OFFSET 4;                \
1097         pushl $__KERNEL_CS;                     \
1098         CFI_ADJUST_CFA_OFFSET 4;                \
1099         pushl $sysenter_past_esp;               \
1100         CFI_ADJUST_CFA_OFFSET 4;                \
1101         CFI_REL_OFFSET eip, 0
1102
1103 ENTRY(debug)
1104         RING0_INT_FRAME
1105         cmpl $ia32_sysenter_target,(%esp)
1106         jne debug_stack_correct
1107         FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
1108 debug_stack_correct:
1109         pushl $-1                       # mark this as an int
1110         CFI_ADJUST_CFA_OFFSET 4
1111         SAVE_ALL
1112         TRACE_IRQS_OFF
1113         xorl %edx,%edx                  # error code 0
1114         movl %esp,%eax                  # pt_regs pointer
1115         call do_debug
1116         jmp ret_from_exception
1117         CFI_ENDPROC
1118 END(debug)
1119
1120 /*
1121  * NMI is doubly nasty. It can happen _while_ we're handling
1122  * a debug fault, and the debug fault hasn't yet been able to
1123  * clear up the stack. So we first check whether we got  an
1124  * NMI on the sysenter entry path, but after that we need to
1125  * check whether we got an NMI on the debug path where the debug
1126  * fault happened on the sysenter path.
1127  */
1128 ENTRY(nmi)
1129         RING0_INT_FRAME
1130         pushl %eax
1131         CFI_ADJUST_CFA_OFFSET 4
1132         movl %ss, %eax
1133         cmpw $__ESPFIX_SS, %ax
1134         popl %eax
1135         CFI_ADJUST_CFA_OFFSET -4
1136         je nmi_espfix_stack
1137         cmpl $ia32_sysenter_target,(%esp)
1138         je nmi_stack_fixup
1139         pushl %eax
1140         CFI_ADJUST_CFA_OFFSET 4
1141         movl %esp,%eax
1142         /* Do not access memory above the end of our stack page,
1143          * it might not exist.
1144          */
1145         andl $(THREAD_SIZE-1),%eax
1146         cmpl $(THREAD_SIZE-20),%eax
1147         popl %eax
1148         CFI_ADJUST_CFA_OFFSET -4
1149         jae nmi_stack_correct
1150         cmpl $ia32_sysenter_target,12(%esp)
1151         je nmi_debug_stack_check
1152 nmi_stack_correct:
1153         /* We have a RING0_INT_FRAME here */
1154         pushl %eax
1155         CFI_ADJUST_CFA_OFFSET 4
1156         SAVE_ALL
1157         TRACE_IRQS_OFF
1158         xorl %edx,%edx          # zero error code
1159         movl %esp,%eax          # pt_regs pointer
1160         call do_nmi
1161         jmp restore_nocheck_notrace
1162         CFI_ENDPROC
1163
1164 nmi_stack_fixup:
1165         RING0_INT_FRAME
1166         FIX_STACK(12,nmi_stack_correct, 1)
1167         jmp nmi_stack_correct
1168
1169 nmi_debug_stack_check:
1170         /* We have a RING0_INT_FRAME here */
1171         cmpw $__KERNEL_CS,16(%esp)
1172         jne nmi_stack_correct
1173         cmpl $debug,(%esp)
1174         jb nmi_stack_correct
1175         cmpl $debug_esp_fix_insn,(%esp)
1176         ja nmi_stack_correct
1177         FIX_STACK(24,nmi_stack_correct, 1)
1178         jmp nmi_stack_correct
1179
1180 nmi_espfix_stack:
1181         /* We have a RING0_INT_FRAME here.
1182          *
1183          * create the pointer to lss back
1184          */
1185         pushl %ss
1186         CFI_ADJUST_CFA_OFFSET 4
1187         pushl %esp
1188         CFI_ADJUST_CFA_OFFSET 4
1189         addw $4, (%esp)
1190         /* copy the iret frame of 12 bytes */
1191         .rept 3
1192         pushl 16(%esp)
1193         CFI_ADJUST_CFA_OFFSET 4
1194         .endr
1195         pushl %eax
1196         CFI_ADJUST_CFA_OFFSET 4
1197         SAVE_ALL
1198         TRACE_IRQS_OFF
1199         FIXUP_ESPFIX_STACK              # %eax == %esp
1200         xorl %edx,%edx                  # zero error code
1201         call do_nmi
1202         RESTORE_REGS
1203         lss 12+4(%esp), %esp            # back to espfix stack
1204         CFI_ADJUST_CFA_OFFSET -24
1205         jmp irq_return
1206         CFI_ENDPROC
1207 END(nmi)
1208
1209 ENTRY(int3)
1210         RING0_INT_FRAME
1211         pushl $-1                       # mark this as an int
1212         CFI_ADJUST_CFA_OFFSET 4
1213         SAVE_ALL
1214         TRACE_IRQS_OFF
1215         xorl %edx,%edx          # zero error code
1216         movl %esp,%eax          # pt_regs pointer
1217         call do_int3
1218         jmp ret_from_exception
1219         CFI_ENDPROC
1220 END(int3)
1221
1222 ENTRY(general_protection)
1223         RING0_EC_FRAME
1224         pushl $do_general_protection
1225         CFI_ADJUST_CFA_OFFSET 4
1226         jmp error_code
1227         CFI_ENDPROC
1228 END(general_protection)
1229
1230 /*
1231  * End of kprobes section
1232  */
1233         .popsection