arch/x86/kernel/entry_64.S

   1 /*
   2  *  linux/arch/x86_64/entry.S
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *  Copyright (C) 2000, 2001, 2002  Andi Kleen SuSE Labs
   6  *  Copyright (C) 2000  Pavel Machek <pavel@suse.cz>
   7  */
   8
   9 /*
  10  * entry.S contains the system-call and fault low-level handling routines.
  11  *
  12  * NOTE: This code handles signal-recognition, which happens every time
  13  * after an interrupt and after each system call.
  14  *
  15  * Normal syscalls and interrupts don't save a full stack frame, this is
  16  * only done for syscall tracing, signals or fork/exec et.al.
  17  *
  18  * A note on terminology:
  19  * - top of stack: Architecture defined interrupt frame from SS to RIP
  20  * at the top of the kernel process stack.
  21  * - partial stack frame: partially saved registers upto R11.
  22  * - full stack frame: Like partial stack frame, but all register saved.
  23  *
  24  * Some macro usage:
  25  * - CFI macros are used to generate dwarf2 unwind information for better
  26  * backtraces. They don't change any code.
  27  * - SAVE_ALL/RESTORE_ALL - Save/restore all registers
  28  * - SAVE_ARGS/RESTORE_ARGS - Save/restore registers that C functions modify.
  29  * There are unfortunately lots of special cases where some registers
  30  * not touched. The macro is a big mess that should be cleaned up.
  31  * - SAVE_REST/RESTORE_REST - Handle the registers not saved by SAVE_ARGS.
  32  * Gives a full stack frame.
  33  * - ENTRY/END Define functions in the symbol table.
  34  * - FIXUP_TOP_OF_STACK/RESTORE_TOP_OF_STACK - Fix up the hardware stack
  35  * frame that is otherwise undefined after a SYSCALL
  36  * - TRACE_IRQ_* - Trace hard interrupt state for lock debugging.
  37  * - errorentry/paranoidentry/zeroentry - Define exception entry points.
  38  */
  39
  40 #include <linux/linkage.h>
  41 #include <asm/segment.h>
  42 #include <asm/cache.h>
  43 #include <asm/errno.h>
  44 #include <asm/dwarf2.h>
  45 #include <asm/calling.h>
  46 #include <asm/asm-offsets.h>
  47 #include <asm/msr.h>
  48 #include <asm/unistd.h>
  49 #include <asm/thread_info.h>
  50 #include <asm/hw_irq.h>
  51 #include <asm/page.h>
  52 #include <asm/irqflags.h>
  53 #include <asm/paravirt.h>
  54
  55         .code64
  56
  57 #ifndef CONFIG_PREEMPT
  58 #define retint_kernel retint_restore_args
  59 #endif
  60
  61 #ifdef CONFIG_PARAVIRT
  62 ENTRY(native_irq_enable_syscall_ret)
  63         movq    %gs:pda_oldrsp,%rsp
  64         swapgs
  65         sysretq
  66 #endif /* CONFIG_PARAVIRT */
  67
  68
  69 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
  70 #ifdef CONFIG_TRACE_IRQFLAGS
  71         bt   $9,EFLAGS-\offset(%rsp)    /* interrupts off? */
  72         jnc  1f
  73         TRACE_IRQS_ON
  74 1:
  75 #endif
  76 .endm
  77
  78 /*
  79  * C code is not supposed to know about undefined top of stack. Every time
  80  * a C function with an pt_regs argument is called from the SYSCALL based
  81  * fast path FIXUP_TOP_OF_STACK is needed.
  82  * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
  83  * manipulation.
  84  */
  85
  86         /* %rsp:at FRAMEEND */
  87         .macro FIXUP_TOP_OF_STACK tmp
  88         movq    %gs:pda_oldrsp,\tmp
  89         movq    \tmp,RSP(%rsp)
  90         movq    $__USER_DS,SS(%rsp)
  91         movq    $__USER_CS,CS(%rsp)
  92         movq    $-1,RCX(%rsp)
  93         movq    R11(%rsp),\tmp  /* get eflags */
  94         movq    \tmp,EFLAGS(%rsp)
  95         .endm
  96
  97         .macro RESTORE_TOP_OF_STACK tmp,offset=0
  98         movq   RSP-\offset(%rsp),\tmp
  99         movq   \tmp,%gs:pda_oldrsp
 100         movq   EFLAGS-\offset(%rsp),\tmp
 101         movq   \tmp,R11-\offset(%rsp)
 102         .endm
 103
 104         .macro FAKE_STACK_FRAME child_rip
 105         /* push in order ss, rsp, eflags, cs, rip */
 106         xorl %eax, %eax
 107         pushq %rax /* ss */
 108         CFI_ADJUST_CFA_OFFSET   8
 109         /*CFI_REL_OFFSET        ss,0*/
 110         pushq %rax /* rsp */
 111         CFI_ADJUST_CFA_OFFSET   8
 112         CFI_REL_OFFSET  rsp,0
 113         pushq $(1<<9) /* eflags - interrupts on */
 114         CFI_ADJUST_CFA_OFFSET   8
 115         /*CFI_REL_OFFSET        rflags,0*/
 116         pushq $__KERNEL_CS /* cs */
 117         CFI_ADJUST_CFA_OFFSET   8
 118         /*CFI_REL_OFFSET        cs,0*/
 119         pushq \child_rip /* rip */
 120         CFI_ADJUST_CFA_OFFSET   8
 121         CFI_REL_OFFSET  rip,0
 122         pushq   %rax /* orig rax */
 123         CFI_ADJUST_CFA_OFFSET   8
 124         .endm
 125
 126         .macro UNFAKE_STACK_FRAME
 127         addq $8*6, %rsp
 128         CFI_ADJUST_CFA_OFFSET   -(6*8)
 129         .endm
 130
 131         .macro  CFI_DEFAULT_STACK start=1
 132         .if \start
 133         CFI_STARTPROC   simple
 134         CFI_SIGNAL_FRAME
 135         CFI_DEF_CFA     rsp,SS+8
 136         .else
 137         CFI_DEF_CFA_OFFSET SS+8
 138         .endif
 139         CFI_REL_OFFSET  r15,R15
 140         CFI_REL_OFFSET  r14,R14
 141         CFI_REL_OFFSET  r13,R13
 142         CFI_REL_OFFSET  r12,R12
 143         CFI_REL_OFFSET  rbp,RBP
 144         CFI_REL_OFFSET  rbx,RBX
 145         CFI_REL_OFFSET  r11,R11
 146         CFI_REL_OFFSET  r10,R10
 147         CFI_REL_OFFSET  r9,R9
 148         CFI_REL_OFFSET  r8,R8
 149         CFI_REL_OFFSET  rax,RAX
 150         CFI_REL_OFFSET  rcx,RCX
 151         CFI_REL_OFFSET  rdx,RDX
 152         CFI_REL_OFFSET  rsi,RSI
 153         CFI_REL_OFFSET  rdi,RDI
 154         CFI_REL_OFFSET  rip,RIP
 155         /*CFI_REL_OFFSET        cs,CS*/
 156         /*CFI_REL_OFFSET        rflags,EFLAGS*/
 157         CFI_REL_OFFSET  rsp,RSP
 158         /*CFI_REL_OFFSET        ss,SS*/
 159         .endm
 160 /*
 161  * A newly forked process directly context switches into this.
 162  */
 163 /* rdi: prev */
 164 ENTRY(ret_from_fork)
 165         CFI_DEFAULT_STACK
 166         push kernel_eflags(%rip)
 167         CFI_ADJUST_CFA_OFFSET 4
 168         popf                            # reset kernel eflags
 169         CFI_ADJUST_CFA_OFFSET -4
 170         call schedule_tail
 171         GET_THREAD_INFO(%rcx)
 172         testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%rcx)
 173         jnz rff_trace
 174 rff_action:
 175         RESTORE_REST
 176         testl $3,CS-ARGOFFSET(%rsp)     # from kernel_thread?
 177         je   int_ret_from_sys_call
 178         testl $_TIF_IA32,threadinfo_flags(%rcx)
 179         jnz  int_ret_from_sys_call
 180         RESTORE_TOP_OF_STACK %rdi,ARGOFFSET
 181         jmp ret_from_sys_call
 182 rff_trace:
 183         movq %rsp,%rdi
 184         call syscall_trace_leave
 185         GET_THREAD_INFO(%rcx)
 186         jmp rff_action
 187         CFI_ENDPROC
 188 END(ret_from_fork)
 189
 190 /*
 191  * System call entry. Upto 6 arguments in registers are supported.
 192  *
 193  * SYSCALL does not save anything on the stack and does not change the
 194  * stack pointer.
 195  */
 196
 197 /*
 198  * Register setup:
 199  * rax  system call number
 200  * rdi  arg0
 201  * rcx  return address for syscall/sysret, C arg3
 202  * rsi  arg1
 203  * rdx  arg2
 204  * r10  arg3    (--> moved to rcx for C)
 205  * r8   arg4
 206  * r9   arg5
 207  * r11  eflags for syscall/sysret, temporary for C
 208  * r12-r15,rbp,rbx saved by C code, not touched.
 209  *
 210  * Interrupts are off on entry.
 211  * Only called from user space.
 212  *
 213  * XXX  if we had a free scratch register we could save the RSP into the stack frame
 214  *      and report it properly in ps. Unfortunately we haven't.
 215  *
 216  * When user can change the frames always force IRET. That is because
 217  * it deals with uncanonical addresses better. SYSRET has trouble
 218  * with them due to bugs in both AMD and Intel CPUs.
 219  */
 220
 221 ENTRY(system_call)
 222         CFI_STARTPROC   simple
 223         CFI_SIGNAL_FRAME
 224         CFI_DEF_CFA     rsp,PDA_STACKOFFSET
 225         CFI_REGISTER    rip,rcx
 226         /*CFI_REGISTER  rflags,r11*/
 227         SWAPGS_UNSAFE_STACK
 228         /*
 229          * A hypervisor implementation might want to use a label
 230          * after the swapgs, so that it can do the swapgs
 231          * for the guest and jump here on syscall.
 232          */
 233 ENTRY(system_call_after_swapgs)
 234
 235         movq    %rsp,%gs:pda_oldrsp
 236         movq    %gs:pda_kernelstack,%rsp
 237         /*
 238          * No need to follow this irqs off/on section - it's straight
 239          * and short:
 240          */
 241         ENABLE_INTERRUPTS(CLBR_NONE)
 242         SAVE_ARGS 8,1
 243         movq  %rax,ORIG_RAX-ARGOFFSET(%rsp)
 244         movq  %rcx,RIP-ARGOFFSET(%rsp)
 245         CFI_REL_OFFSET rip,RIP-ARGOFFSET
 246         GET_THREAD_INFO(%rcx)
 247         testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%rcx)
 248         jnz tracesys
 249         cmpq $__NR_syscall_max,%rax
 250         ja badsys
 251         movq %r10,%rcx
 252         call *sys_call_table(,%rax,8)  # XXX:    rip relative
 253         movq %rax,RAX-ARGOFFSET(%rsp)
 254 /*
 255  * Syscall return path ending with SYSRET (fast path)
 256  * Has incomplete stack frame and undefined top of stack.
 257  */
 258 ret_from_sys_call:
 259         movl $_TIF_ALLWORK_MASK,%edi
 260         /* edi: flagmask */
 261 sysret_check:
 262         LOCKDEP_SYS_EXIT
 263         GET_THREAD_INFO(%rcx)
 264         DISABLE_INTERRUPTS(CLBR_NONE)
 265         TRACE_IRQS_OFF
 266         movl threadinfo_flags(%rcx),%edx
 267         andl %edi,%edx
 268         jnz  sysret_careful
 269         CFI_REMEMBER_STATE
 270         /*
 271          * sysretq will re-enable interrupts:
 272          */
 273         TRACE_IRQS_ON
 274         movq RIP-ARGOFFSET(%rsp),%rcx
 275         CFI_REGISTER    rip,rcx
 276         RESTORE_ARGS 0,-ARG_SKIP,1
 277         /*CFI_REGISTER  rflags,r11*/
 278         ENABLE_INTERRUPTS_SYSCALL_RET
 279
 280         CFI_RESTORE_STATE
 281         /* Handle reschedules */
 282         /* edx: work, edi: workmask */
 283 sysret_careful:
 284         bt $TIF_NEED_RESCHED,%edx
 285         jnc sysret_signal
 286         TRACE_IRQS_ON
 287         ENABLE_INTERRUPTS(CLBR_NONE)
 288         pushq %rdi
 289         CFI_ADJUST_CFA_OFFSET 8
 290         call schedule
 291         popq  %rdi
 292         CFI_ADJUST_CFA_OFFSET -8
 293         jmp sysret_check
 294
 295         /* Handle a signal */
 296 sysret_signal:
 297         TRACE_IRQS_ON
 298         ENABLE_INTERRUPTS(CLBR_NONE)
 299         testl $_TIF_DO_NOTIFY_MASK,%edx
 300         jz    1f
 301
 302         /* Really a signal */
 303         /* edx: work flags (arg3) */
 304         leaq do_notify_resume(%rip),%rax
 305         leaq -ARGOFFSET(%rsp),%rdi # &pt_regs -> arg1
 306         xorl %esi,%esi # oldset -> arg2
 307         call ptregscall_common
 308 1:      movl $_TIF_NEED_RESCHED,%edi
 309         /* Use IRET because user could have changed frame. This
 310            works because ptregscall_common has called FIXUP_TOP_OF_STACK. */
 311         DISABLE_INTERRUPTS(CLBR_NONE)
 312         TRACE_IRQS_OFF
 313         jmp int_with_check
 314
 315 badsys:
 316         movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
 317         jmp ret_from_sys_call
 318
 319         /* Do syscall tracing */
 320 tracesys:
 321         SAVE_REST
 322         movq $-ENOSYS,RAX(%rsp)
 323         FIXUP_TOP_OF_STACK %rdi
 324         movq %rsp,%rdi
 325         call syscall_trace_enter
 326         LOAD_ARGS ARGOFFSET  /* reload args from stack in case ptrace changed it */
 327         RESTORE_REST
 328         cmpq $__NR_syscall_max,%rax
 329         movq $-ENOSYS,%rcx
 330         cmova %rcx,%rax
 331         ja  1f
 332         movq %r10,%rcx  /* fixup for C */
 333         call *sys_call_table(,%rax,8)
 334 1:      movq %rax,RAX-ARGOFFSET(%rsp)
 335         /* Use IRET because user could have changed frame */
 336
 337 /*
 338  * Syscall return path ending with IRET.
 339  * Has correct top of stack, but partial stack frame.
 340  */
 341         .globl int_ret_from_sys_call
 342 int_ret_from_sys_call:
 343         DISABLE_INTERRUPTS(CLBR_NONE)
 344         TRACE_IRQS_OFF
 345         testl $3,CS-ARGOFFSET(%rsp)
 346         je retint_restore_args
 347         movl $_TIF_ALLWORK_MASK,%edi
 348         /* edi: mask to check */
 349 int_with_check:
 350         LOCKDEP_SYS_EXIT_IRQ
 351         GET_THREAD_INFO(%rcx)
 352         movl threadinfo_flags(%rcx),%edx
 353         andl %edi,%edx
 354         jnz   int_careful
 355         andl    $~TS_COMPAT,threadinfo_status(%rcx)
 356         jmp   retint_swapgs
 357
 358         /* Either reschedule or signal or syscall exit tracking needed. */
 359         /* First do a reschedule test. */
 360         /* edx: work, edi: workmask */
 361 int_careful:
 362         bt $TIF_NEED_RESCHED,%edx
 363         jnc  int_very_careful
 364         TRACE_IRQS_ON
 365         ENABLE_INTERRUPTS(CLBR_NONE)
 366         pushq %rdi
 367         CFI_ADJUST_CFA_OFFSET 8
 368         call schedule
 369         popq %rdi
 370         CFI_ADJUST_CFA_OFFSET -8
 371         DISABLE_INTERRUPTS(CLBR_NONE)
 372         TRACE_IRQS_OFF
 373         jmp int_with_check
 374
 375         /* handle signals and tracing -- both require a full stack frame */
 376 int_very_careful:
 377         TRACE_IRQS_ON
 378         ENABLE_INTERRUPTS(CLBR_NONE)
 379         SAVE_REST
 380         /* Check for syscall exit trace */
 381         testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edx
 382         jz int_signal
 383         pushq %rdi
 384         CFI_ADJUST_CFA_OFFSET 8
 385         leaq 8(%rsp),%rdi       # &ptregs -> arg1
 386         call syscall_trace_leave
 387         popq %rdi
 388         CFI_ADJUST_CFA_OFFSET -8
 389         andl $~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edi
 390         jmp int_restore_rest
 391
 392 int_signal:
 393         testl $_TIF_DO_NOTIFY_MASK,%edx
 394         jz 1f
 395         movq %rsp,%rdi          # &ptregs -> arg1
 396         xorl %esi,%esi          # oldset -> arg2
 397         call do_notify_resume
 398 1:      movl $_TIF_NEED_RESCHED,%edi
 399 int_restore_rest:
 400         RESTORE_REST
 401         DISABLE_INTERRUPTS(CLBR_NONE)
 402         TRACE_IRQS_OFF
 403         jmp int_with_check
 404         CFI_ENDPROC
 405 END(system_call)
 406
 407 /*
 408  * Certain special system calls that need to save a complete full stack frame.
 409  */
 410
 411         .macro PTREGSCALL label,func,arg
 412         .globl \label
 413 \label:
 414         leaq    \func(%rip),%rax
 415         leaq    -ARGOFFSET+8(%rsp),\arg /* 8 for return address */
 416         jmp     ptregscall_common
 417 END(\label)
 418         .endm
 419
 420         CFI_STARTPROC
 421
 422         PTREGSCALL stub_clone, sys_clone, %r8
 423         PTREGSCALL stub_fork, sys_fork, %rdi
 424         PTREGSCALL stub_vfork, sys_vfork, %rdi
 425         PTREGSCALL stub_rt_sigsuspend, sys_rt_sigsuspend, %rdx
 426         PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
 427         PTREGSCALL stub_iopl, sys_iopl, %rsi
 428
 429 ENTRY(ptregscall_common)
 430         popq %r11
 431         CFI_ADJUST_CFA_OFFSET -8
 432         CFI_REGISTER rip, r11
 433         SAVE_REST
 434         movq %r11, %r15
 435         CFI_REGISTER rip, r15
 436         FIXUP_TOP_OF_STACK %r11
 437         call *%rax
 438         RESTORE_TOP_OF_STACK %r11
 439         movq %r15, %r11
 440         CFI_REGISTER rip, r11
 441         RESTORE_REST
 442         pushq %r11
 443         CFI_ADJUST_CFA_OFFSET 8
 444         CFI_REL_OFFSET rip, 0
 445         ret
 446         CFI_ENDPROC
 447 END(ptregscall_common)
 448
 449 ENTRY(stub_execve)
 450         CFI_STARTPROC
 451         popq %r11
 452         CFI_ADJUST_CFA_OFFSET -8
 453         CFI_REGISTER rip, r11
 454         SAVE_REST
 455         FIXUP_TOP_OF_STACK %r11
 456         call sys_execve
 457         RESTORE_TOP_OF_STACK %r11
 458         movq %rax,RAX(%rsp)
 459         RESTORE_REST
 460         jmp int_ret_from_sys_call
 461         CFI_ENDPROC
 462 END(stub_execve)
 463
 464 /*
 465  * sigreturn is special because it needs to restore all registers on return.
 466  * This cannot be done with SYSRET, so use the IRET return path instead.
 467  */
 468 ENTRY(stub_rt_sigreturn)
 469         CFI_STARTPROC
 470         addq $8, %rsp
 471         CFI_ADJUST_CFA_OFFSET   -8
 472         SAVE_REST
 473         movq %rsp,%rdi
 474         FIXUP_TOP_OF_STACK %r11
 475         call sys_rt_sigreturn
 476         movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
 477         RESTORE_REST
 478         jmp int_ret_from_sys_call
 479         CFI_ENDPROC
 480 END(stub_rt_sigreturn)
 481
 482 /*
 483  * initial frame state for interrupts and exceptions
 484  */
 485         .macro _frame ref
 486         CFI_STARTPROC simple
 487         CFI_SIGNAL_FRAME
 488         CFI_DEF_CFA rsp,SS+8-\ref
 489         /*CFI_REL_OFFSET ss,SS-\ref*/
 490         CFI_REL_OFFSET rsp,RSP-\ref
 491         /*CFI_REL_OFFSET rflags,EFLAGS-\ref*/
 492         /*CFI_REL_OFFSET cs,CS-\ref*/
 493         CFI_REL_OFFSET rip,RIP-\ref
 494         .endm
 495
 496 /* initial frame state for interrupts (and exceptions without error code) */
 497 #define INTR_FRAME _frame RIP
 498 /* initial frame state for exceptions with error code (and interrupts with
 499    vector already pushed) */
 500 #define XCPT_FRAME _frame ORIG_RAX
 501
 502 /*
 503  * Interrupt entry/exit.
 504  *
 505  * Interrupt entry points save only callee clobbered registers in fast path.
 506  *
 507  * Entry runs with interrupts off.
 508  */
 509
 510 /* 0(%rsp): interrupt number */
 511         .macro interrupt func
 512         cld
 513         SAVE_ARGS
 514         leaq -ARGOFFSET(%rsp),%rdi      # arg1 for handler
 515         pushq %rbp
 516         CFI_ADJUST_CFA_OFFSET   8
 517         CFI_REL_OFFSET          rbp, 0
 518         movq %rsp,%rbp
 519         CFI_DEF_CFA_REGISTER    rbp
 520         testl $3,CS(%rdi)
 521         je 1f
 522         SWAPGS
 523         /* irqcount is used to check if a CPU is already on an interrupt
 524            stack or not. While this is essentially redundant with preempt_count
 525            it is a little cheaper to use a separate counter in the PDA
 526            (short of moving irq_enter into assembly, which would be too
 527             much work) */
 528 1:      incl    %gs:pda_irqcount
 529         cmoveq %gs:pda_irqstackptr,%rsp
 530         push    %rbp                    # backlink for old unwinder
 531         /*
 532          * We entered an interrupt context - irqs are off:
 533          */
 534         TRACE_IRQS_OFF
 535         call \func
 536         .endm
 537
 538 ENTRY(common_interrupt)
 539         XCPT_FRAME
 540         interrupt do_IRQ
 541         /* 0(%rsp): oldrsp-ARGOFFSET */
 542 ret_from_intr:
 543         DISABLE_INTERRUPTS(CLBR_NONE)
 544         TRACE_IRQS_OFF
 545         decl %gs:pda_irqcount
 546         leaveq
 547         CFI_DEF_CFA_REGISTER    rsp
 548         CFI_ADJUST_CFA_OFFSET   -8
 549 exit_intr:
 550         GET_THREAD_INFO(%rcx)
 551         testl $3,CS-ARGOFFSET(%rsp)
 552         je retint_kernel
 553
 554         /* Interrupt came from user space */
 555         /*
 556          * Has a correct top of stack, but a partial stack frame
 557          * %rcx: thread info. Interrupts off.
 558          */
 559 retint_with_reschedule:
 560         movl $_TIF_WORK_MASK,%edi
 561 retint_check:
 562         LOCKDEP_SYS_EXIT_IRQ
 563         movl threadinfo_flags(%rcx),%edx
 564         andl %edi,%edx
 565         CFI_REMEMBER_STATE
 566         jnz  retint_careful
 567
 568 retint_swapgs:          /* return to user-space */
 569         /*
 570          * The iretq could re-enable interrupts:
 571          */
 572         DISABLE_INTERRUPTS(CLBR_ANY)
 573         TRACE_IRQS_IRETQ
 574         SWAPGS
 575         jmp restore_args
 576
 577 retint_restore_args:    /* return to kernel space */
 578         DISABLE_INTERRUPTS(CLBR_ANY)
 579         /*
 580          * The iretq could re-enable interrupts:
 581          */
 582         TRACE_IRQS_IRETQ
 583 restore_args:
 584         RESTORE_ARGS 0,8,0
 585 iret_label:
 586 #ifdef CONFIG_PARAVIRT
 587         INTERRUPT_RETURN
 588 #endif
 589 ENTRY(native_iret)
 590         iretq
 591
 592         .section __ex_table,"a"
 593         .quad native_iret, bad_iret
 594         .previous
 595         .section .fixup,"ax"
 596         /* force a signal here? this matches i386 behaviour */
 597         /* running with kernel gs */
 598 bad_iret:
 599         movq $11,%rdi   /* SIGSEGV */
 600         TRACE_IRQS_ON
 601         ENABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI))
 602         jmp do_exit
 603         .previous
 604
 605         /* edi: workmask, edx: work */
 606 retint_careful:
 607         CFI_RESTORE_STATE
 608         bt    $TIF_NEED_RESCHED,%edx
 609         jnc   retint_signal
 610         TRACE_IRQS_ON
 611         ENABLE_INTERRUPTS(CLBR_NONE)
 612         pushq %rdi
 613         CFI_ADJUST_CFA_OFFSET   8
 614         call  schedule
 615         popq %rdi
 616         CFI_ADJUST_CFA_OFFSET   -8
 617         GET_THREAD_INFO(%rcx)
 618         DISABLE_INTERRUPTS(CLBR_NONE)
 619         TRACE_IRQS_OFF
 620         jmp retint_check
 621
 622 retint_signal:
 623         testl $_TIF_DO_NOTIFY_MASK,%edx
 624         jz    retint_swapgs
 625         TRACE_IRQS_ON
 626         ENABLE_INTERRUPTS(CLBR_NONE)
 627         SAVE_REST
 628         movq $-1,ORIG_RAX(%rsp)
 629         xorl %esi,%esi          # oldset
 630         movq %rsp,%rdi          # &pt_regs
 631         call do_notify_resume
 632         RESTORE_REST
 633         DISABLE_INTERRUPTS(CLBR_NONE)
 634         TRACE_IRQS_OFF
 635         movl $_TIF_NEED_RESCHED,%edi
 636         GET_THREAD_INFO(%rcx)
 637         jmp retint_check
 638
 639 #ifdef CONFIG_PREEMPT
 640         /* Returning to kernel space. Check if we need preemption */
 641         /* rcx:  threadinfo. interrupts off. */
 642 ENTRY(retint_kernel)
 643         cmpl $0,threadinfo_preempt_count(%rcx)
 644         jnz  retint_restore_args
 645         bt  $TIF_NEED_RESCHED,threadinfo_flags(%rcx)
 646         jnc  retint_restore_args
 647         bt   $9,EFLAGS-ARGOFFSET(%rsp)  /* interrupts off? */
 648         jnc  retint_restore_args
 649         call preempt_schedule_irq
 650         jmp exit_intr
 651 #endif
 652
 653         CFI_ENDPROC
 654 END(common_interrupt)
 655
 656 /*
 657  * APIC interrupts.
 658  */
 659         .macro apicinterrupt num,func
 660         INTR_FRAME
 661         pushq $~(\num)
 662         CFI_ADJUST_CFA_OFFSET 8
 663         interrupt \func
 664         jmp ret_from_intr
 665         CFI_ENDPROC
 666         .endm
 667
 668 ENTRY(thermal_interrupt)
 669         apicinterrupt THERMAL_APIC_VECTOR,smp_thermal_interrupt
 670 END(thermal_interrupt)
 671
 672 ENTRY(threshold_interrupt)
 673         apicinterrupt THRESHOLD_APIC_VECTOR,mce_threshold_interrupt
 674 END(threshold_interrupt)
 675
 676 #ifdef CONFIG_SMP
 677 ENTRY(reschedule_interrupt)
 678         apicinterrupt RESCHEDULE_VECTOR,smp_reschedule_interrupt
 679 END(reschedule_interrupt)
 680
 681         .macro INVALIDATE_ENTRY num
 682 ENTRY(invalidate_interrupt\num)
 683         apicinterrupt INVALIDATE_TLB_VECTOR_START+\num,smp_invalidate_interrupt
 684 END(invalidate_interrupt\num)
 685         .endm
 686
 687         INVALIDATE_ENTRY 0
 688         INVALIDATE_ENTRY 1
 689         INVALIDATE_ENTRY 2
 690         INVALIDATE_ENTRY 3
 691         INVALIDATE_ENTRY 4
 692         INVALIDATE_ENTRY 5
 693         INVALIDATE_ENTRY 6
 694         INVALIDATE_ENTRY 7
 695
 696 ENTRY(call_function_interrupt)
 697         apicinterrupt CALL_FUNCTION_VECTOR,smp_call_function_interrupt
 698 END(call_function_interrupt)
 699 ENTRY(irq_move_cleanup_interrupt)
 700         apicinterrupt IRQ_MOVE_CLEANUP_VECTOR,smp_irq_move_cleanup_interrupt
 701 END(irq_move_cleanup_interrupt)
 702 #endif
 703
 704 ENTRY(apic_timer_interrupt)
 705         apicinterrupt LOCAL_TIMER_VECTOR,smp_apic_timer_interrupt
 706 END(apic_timer_interrupt)
 707
 708 ENTRY(error_interrupt)
 709         apicinterrupt ERROR_APIC_VECTOR,smp_error_interrupt
 710 END(error_interrupt)
 711
 712 ENTRY(spurious_interrupt)
 713         apicinterrupt SPURIOUS_APIC_VECTOR,smp_spurious_interrupt
 714 END(spurious_interrupt)
 715
 716 /*
 717  * Exception entry points.
 718  */
 719         .macro zeroentry sym
 720         INTR_FRAME
 721         pushq $0        /* push error code/oldrax */
 722         CFI_ADJUST_CFA_OFFSET 8
 723         pushq %rax      /* push real oldrax to the rdi slot */
 724         CFI_ADJUST_CFA_OFFSET 8
 725         CFI_REL_OFFSET rax,0
 726         leaq  \sym(%rip),%rax
 727         jmp error_entry
 728         CFI_ENDPROC
 729         .endm
 730
 731         .macro errorentry sym
 732         XCPT_FRAME
 733         pushq %rax
 734         CFI_ADJUST_CFA_OFFSET 8
 735         CFI_REL_OFFSET rax,0
 736         leaq  \sym(%rip),%rax
 737         jmp error_entry
 738         CFI_ENDPROC
 739         .endm
 740
 741         /* error code is on the stack already */
 742         /* handle NMI like exceptions that can happen everywhere */
 743         .macro paranoidentry sym, ist=0, irqtrace=1
 744         SAVE_ALL
 745         cld
 746         movl $1,%ebx
 747         movl  $MSR_GS_BASE,%ecx
 748         rdmsr
 749         testl %edx,%edx
 750         js    1f
 751         SWAPGS
 752         xorl  %ebx,%ebx
 753 1:
 754         .if \ist
 755         movq    %gs:pda_data_offset, %rbp
 756         .endif
 757         movq %rsp,%rdi
 758         movq ORIG_RAX(%rsp),%rsi
 759         movq $-1,ORIG_RAX(%rsp)
 760         .if \ist
 761         subq    $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
 762         .endif
 763         call \sym
 764         .if \ist
 765         addq    $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
 766         .endif
 767         DISABLE_INTERRUPTS(CLBR_NONE)
 768         .if \irqtrace
 769         TRACE_IRQS_OFF
 770         .endif
 771         .endm
 772
 773         /*
 774          * "Paranoid" exit path from exception stack.
 775          * Paranoid because this is used by NMIs and cannot take
 776          * any kernel state for granted.
 777          * We don't do kernel preemption checks here, because only
 778          * NMI should be common and it does not enable IRQs and
 779          * cannot get reschedule ticks.
 780          *
 781          * "trace" is 0 for the NMI handler only, because irq-tracing
 782          * is fundamentally NMI-unsafe. (we cannot change the soft and
 783          * hard flags at once, atomically)
 784          */
 785         .macro paranoidexit trace=1
 786         /* ebx: no swapgs flag */
 787 paranoid_exit\trace:
 788         testl %ebx,%ebx                         /* swapgs needed? */
 789         jnz paranoid_restore\trace
 790         testl $3,CS(%rsp)
 791         jnz   paranoid_userspace\trace
 792 paranoid_swapgs\trace:
 793         .if \trace
 794         TRACE_IRQS_IRETQ 0
 795         .endif
 796         SWAPGS_UNSAFE_STACK
 797 paranoid_restore\trace:
 798         RESTORE_ALL 8
 799         INTERRUPT_RETURN
 800 paranoid_userspace\trace:
 801         GET_THREAD_INFO(%rcx)
 802         movl threadinfo_flags(%rcx),%ebx
 803         andl $_TIF_WORK_MASK,%ebx
 804         jz paranoid_swapgs\trace
 805         movq %rsp,%rdi                  /* &pt_regs */
 806         call sync_regs
 807         movq %rax,%rsp                  /* switch stack for scheduling */
 808         testl $_TIF_NEED_RESCHED,%ebx
 809         jnz paranoid_schedule\trace
 810         movl %ebx,%edx                  /* arg3: thread flags */
 811         .if \trace
 812         TRACE_IRQS_ON
 813         .endif
 814         ENABLE_INTERRUPTS(CLBR_NONE)
 815         xorl %esi,%esi                  /* arg2: oldset */
 816         movq %rsp,%rdi                  /* arg1: &pt_regs */
 817         call do_notify_resume
 818         DISABLE_INTERRUPTS(CLBR_NONE)
 819         .if \trace
 820         TRACE_IRQS_OFF
 821         .endif
 822         jmp paranoid_userspace\trace
 823 paranoid_schedule\trace:
 824         .if \trace
 825         TRACE_IRQS_ON
 826         .endif
 827         ENABLE_INTERRUPTS(CLBR_ANY)
 828         call schedule
 829         DISABLE_INTERRUPTS(CLBR_ANY)
 830         .if \trace
 831         TRACE_IRQS_OFF
 832         .endif
 833         jmp paranoid_userspace\trace
 834         CFI_ENDPROC
 835         .endm
 836
 837 /*
 838  * Exception entry point. This expects an error code/orig_rax on the stack
 839  * and the exception handler in %rax.
 840  */
 841 KPROBE_ENTRY(error_entry)
 842         _frame RDI
 843         CFI_REL_OFFSET rax,0
 844         /* rdi slot contains rax, oldrax contains error code */
 845         cld
 846         subq  $14*8,%rsp
 847         CFI_ADJUST_CFA_OFFSET   (14*8)
 848         movq %rsi,13*8(%rsp)
 849         CFI_REL_OFFSET  rsi,RSI
 850         movq 14*8(%rsp),%rsi    /* load rax from rdi slot */
 851         CFI_REGISTER    rax,rsi
 852         movq %rdx,12*8(%rsp)
 853         CFI_REL_OFFSET  rdx,RDX
 854         movq %rcx,11*8(%rsp)
 855         CFI_REL_OFFSET  rcx,RCX
 856         movq %rsi,10*8(%rsp)    /* store rax */
 857         CFI_REL_OFFSET  rax,RAX
 858         movq %r8, 9*8(%rsp)
 859         CFI_REL_OFFSET  r8,R8
 860         movq %r9, 8*8(%rsp)
 861         CFI_REL_OFFSET  r9,R9
 862         movq %r10,7*8(%rsp)
 863         CFI_REL_OFFSET  r10,R10
 864         movq %r11,6*8(%rsp)
 865         CFI_REL_OFFSET  r11,R11
 866         movq %rbx,5*8(%rsp)
 867         CFI_REL_OFFSET  rbx,RBX
 868         movq %rbp,4*8(%rsp)
 869         CFI_REL_OFFSET  rbp,RBP
 870         movq %r12,3*8(%rsp)
 871         CFI_REL_OFFSET  r12,R12
 872         movq %r13,2*8(%rsp)
 873         CFI_REL_OFFSET  r13,R13
 874         movq %r14,1*8(%rsp)
 875         CFI_REL_OFFSET  r14,R14
 876         movq %r15,(%rsp)
 877         CFI_REL_OFFSET  r15,R15
 878         xorl %ebx,%ebx
 879         testl $3,CS(%rsp)
 880         je  error_kernelspace
 881 error_swapgs:
 882         SWAPGS
 883 error_sti:
 884         movq %rdi,RDI(%rsp)
 885         CFI_REL_OFFSET  rdi,RDI
 886         movq %rsp,%rdi
 887         movq ORIG_RAX(%rsp),%rsi        /* get error code */
 888         movq $-1,ORIG_RAX(%rsp)
 889         call *%rax
 890         /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
 891 error_exit:
 892         movl %ebx,%eax
 893         RESTORE_REST
 894         DISABLE_INTERRUPTS(CLBR_NONE)
 895         TRACE_IRQS_OFF
 896         GET_THREAD_INFO(%rcx)
 897         testl %eax,%eax
 898         jne  retint_kernel
 899         LOCKDEP_SYS_EXIT_IRQ
 900         movl  threadinfo_flags(%rcx),%edx
 901         movl  $_TIF_WORK_MASK,%edi
 902         andl  %edi,%edx
 903         jnz  retint_careful
 904         jmp retint_swapgs
 905         CFI_ENDPROC
 906
 907 error_kernelspace:
 908         incl %ebx
 909        /* There are two places in the kernel that can potentially fault with
 910           usergs. Handle them here. The exception handlers after
 911            iret run with kernel gs again, so don't set the user space flag.
 912            B stepping K8s sometimes report an truncated RIP for IRET
 913            exceptions returning to compat mode. Check for these here too. */
 914         leaq iret_label(%rip),%rbp
 915         cmpq %rbp,RIP(%rsp)
 916         je   error_swapgs
 917         movl %ebp,%ebp  /* zero extend */
 918         cmpq %rbp,RIP(%rsp)
 919         je   error_swapgs
 920         cmpq $gs_change,RIP(%rsp)
 921         je   error_swapgs
 922         jmp  error_sti
 923 KPROBE_END(error_entry)
 924
 925        /* Reload gs selector with exception handling */
 926        /* edi:  new selector */
 927 ENTRY(load_gs_index)
 928         CFI_STARTPROC
 929         pushf
 930         CFI_ADJUST_CFA_OFFSET 8
 931         DISABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI))
 932         SWAPGS
 933 gs_change:
 934         movl %edi,%gs
 935 2:      mfence          /* workaround */
 936         SWAPGS
 937         popf
 938         CFI_ADJUST_CFA_OFFSET -8
 939         ret
 940         CFI_ENDPROC
 941 ENDPROC(load_gs_index)
 942
 943         .section __ex_table,"a"
 944         .align 8
 945         .quad gs_change,bad_gs
 946         .previous
 947         .section .fixup,"ax"
 948         /* running with kernelgs */
 949 bad_gs:
 950         SWAPGS                  /* switch back to user gs */
 951         xorl %eax,%eax
 952         movl %eax,%gs
 953         jmp  2b
 954         .previous
 955
 956 /*
 957  * Create a kernel thread.
 958  *
 959  * C extern interface:
 960  *      extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 961  *
 962  * asm input arguments:
 963  *      rdi: fn, rsi: arg, rdx: flags
 964  */
 965 ENTRY(kernel_thread)
 966         CFI_STARTPROC
 967         FAKE_STACK_FRAME $child_rip
 968         SAVE_ALL
 969
 970         # rdi: flags, rsi: usp, rdx: will be &pt_regs
 971         movq %rdx,%rdi
 972         orq  kernel_thread_flags(%rip),%rdi
 973         movq $-1, %rsi
 974         movq %rsp, %rdx
 975
 976         xorl %r8d,%r8d
 977         xorl %r9d,%r9d
 978
 979         # clone now
 980         call do_fork
 981         movq %rax,RAX(%rsp)
 982         xorl %edi,%edi
 983
 984         /*
 985          * It isn't worth to check for reschedule here,
 986          * so internally to the x86_64 port you can rely on kernel_thread()
 987          * not to reschedule the child before returning, this avoids the need
 988          * of hacks for example to fork off the per-CPU idle tasks.
 989          * [Hopefully no generic code relies on the reschedule -AK]
 990          */
 991         RESTORE_ALL
 992         UNFAKE_STACK_FRAME
 993         ret
 994         CFI_ENDPROC
 995 ENDPROC(kernel_thread)
 996
 997 child_rip:
 998         pushq $0                # fake return address
 999         CFI_STARTPROC
1000         /*
1001          * Here we are in the child and the registers are set as they were
1002          * at kernel_thread() invocation in the parent.
1003          */
1004         movq %rdi, %rax
1005         movq %rsi, %rdi
1006         call *%rax
1007         # exit
1008         mov %eax, %edi
1009         call do_exit
1010         CFI_ENDPROC
1011 ENDPROC(child_rip)
1012
1013 /*
1014  * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
1015  *
1016  * C extern interface:
1017  *       extern long execve(char *name, char **argv, char **envp)
1018  *
1019  * asm input arguments:
1020  *      rdi: name, rsi: argv, rdx: envp
1021  *
1022  * We want to fallback into:
1023  *      extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs regs)
1024  *
1025  * do_sys_execve asm fallback arguments:
1026  *      rdi: name, rsi: argv, rdx: envp, fake frame on the stack
1027  */
1028 ENTRY(kernel_execve)
1029         CFI_STARTPROC
1030         FAKE_STACK_FRAME $0
1031         SAVE_ALL
1032         call sys_execve
1033         movq %rax, RAX(%rsp)
1034         RESTORE_REST
1035         testq %rax,%rax
1036         je int_ret_from_sys_call
1037         RESTORE_ARGS
1038         UNFAKE_STACK_FRAME
1039         ret
1040         CFI_ENDPROC
1041 ENDPROC(kernel_execve)
1042
1043 KPROBE_ENTRY(page_fault)
1044         errorentry do_page_fault
1045 KPROBE_END(page_fault)
1046
1047 ENTRY(coprocessor_error)
1048         zeroentry do_coprocessor_error
1049 END(coprocessor_error)
1050
1051 ENTRY(simd_coprocessor_error)
1052         zeroentry do_simd_coprocessor_error
1053 END(simd_coprocessor_error)
1054
1055 ENTRY(device_not_available)
1056         zeroentry math_state_restore
1057 END(device_not_available)
1058
1059         /* runs on exception stack */
1060 KPROBE_ENTRY(debug)
1061         INTR_FRAME
1062         pushq $0
1063         CFI_ADJUST_CFA_OFFSET 8
1064         paranoidentry do_debug, DEBUG_STACK
1065         paranoidexit
1066 KPROBE_END(debug)
1067
1068         /* runs on exception stack */
1069 KPROBE_ENTRY(nmi)
1070         INTR_FRAME
1071         pushq $-1
1072         CFI_ADJUST_CFA_OFFSET 8
1073         paranoidentry do_nmi, 0, 0
1074 #ifdef CONFIG_TRACE_IRQFLAGS
1075         paranoidexit 0
1076 #else
1077         jmp paranoid_exit1
1078         CFI_ENDPROC
1079 #endif
1080 KPROBE_END(nmi)
1081
1082 KPROBE_ENTRY(int3)
1083         INTR_FRAME
1084         pushq $0
1085         CFI_ADJUST_CFA_OFFSET 8
1086         paranoidentry do_int3, DEBUG_STACK
1087         jmp paranoid_exit1
1088         CFI_ENDPROC
1089 KPROBE_END(int3)
1090
1091 ENTRY(overflow)
1092         zeroentry do_overflow
1093 END(overflow)
1094
1095 ENTRY(bounds)
1096         zeroentry do_bounds
1097 END(bounds)
1098
1099 ENTRY(invalid_op)
1100         zeroentry do_invalid_op
1101 END(invalid_op)
1102
1103 ENTRY(coprocessor_segment_overrun)
1104         zeroentry do_coprocessor_segment_overrun
1105 END(coprocessor_segment_overrun)
1106
1107 ENTRY(reserved)
1108         zeroentry do_reserved
1109 END(reserved)
1110
1111         /* runs on exception stack */
1112 ENTRY(double_fault)
1113         XCPT_FRAME
1114         paranoidentry do_double_fault
1115         jmp paranoid_exit1
1116         CFI_ENDPROC
1117 END(double_fault)
1118
1119 ENTRY(invalid_TSS)
1120         errorentry do_invalid_TSS
1121 END(invalid_TSS)
1122
1123 ENTRY(segment_not_present)
1124         errorentry do_segment_not_present
1125 END(segment_not_present)
1126
1127         /* runs on exception stack */
1128 ENTRY(stack_segment)
1129         XCPT_FRAME
1130         paranoidentry do_stack_segment
1131         jmp paranoid_exit1
1132         CFI_ENDPROC
1133 END(stack_segment)
1134
1135 KPROBE_ENTRY(general_protection)
1136         errorentry do_general_protection
1137 KPROBE_END(general_protection)
1138
1139 ENTRY(alignment_check)
1140         errorentry do_alignment_check
1141 END(alignment_check)
1142
1143 ENTRY(divide_error)
1144         zeroentry do_divide_error
1145 END(divide_error)
1146
1147 ENTRY(spurious_interrupt_bug)
1148         zeroentry do_spurious_interrupt_bug
1149 END(spurious_interrupt_bug)
1150
1151 #ifdef CONFIG_X86_MCE
1152         /* runs on exception stack */
1153 ENTRY(machine_check)
1154         INTR_FRAME
1155         pushq $0
1156         CFI_ADJUST_CFA_OFFSET 8
1157         paranoidentry do_machine_check
1158         jmp paranoid_exit1
1159         CFI_ENDPROC
1160 END(machine_check)
1161 #endif
1162
1163 /* Call softirq on interrupt stack. Interrupts are off. */
1164 ENTRY(call_softirq)
1165         CFI_STARTPROC
1166         push %rbp
1167         CFI_ADJUST_CFA_OFFSET   8
1168         CFI_REL_OFFSET rbp,0
1169         mov  %rsp,%rbp
1170         CFI_DEF_CFA_REGISTER rbp
1171         incl %gs:pda_irqcount
1172         cmove %gs:pda_irqstackptr,%rsp
1173         push  %rbp                      # backlink for old unwinder
1174         call __do_softirq
1175         leaveq
1176         CFI_DEF_CFA_REGISTER    rsp
1177         CFI_ADJUST_CFA_OFFSET   -8
1178         decl %gs:pda_irqcount
1179         ret
1180         CFI_ENDPROC
1181 ENDPROC(call_softirq)
1182
1183 KPROBE_ENTRY(ignore_sysret)
1184         CFI_STARTPROC
1185         mov $-ENOSYS,%eax
1186         sysret
1187         CFI_ENDPROC
1188 ENDPROC(ignore_sysret)