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  * Some of this is documented in Documentation/x86/entry_64.txt
  13  *
  14  * NOTE: This code handles signal-recognition, which happens every time
  15  * after an interrupt and after each system call.
  16  *
  17  * Normal syscalls and interrupts don't save a full stack frame, this is
  18  * only done for syscall tracing, signals or fork/exec et.al.
  19  *
  20  * A note on terminology:
  21  * - top of stack: Architecture defined interrupt frame from SS to RIP
  22  * at the top of the kernel process stack.
  23  * - partial stack frame: partially saved registers up to R11.
  24  * - full stack frame: Like partial stack frame, but all register saved.
  25  *
  26  * Some macro usage:
  27  * - CFI macros are used to generate dwarf2 unwind information for better
  28  * backtraces. They don't change any code.
  29  * - SAVE_ALL/RESTORE_ALL - Save/restore all registers
  30  * - SAVE_ARGS/RESTORE_ARGS - Save/restore registers that C functions modify.
  31  * There are unfortunately lots of special cases where some registers
  32  * not touched. The macro is a big mess that should be cleaned up.
  33  * - SAVE_REST/RESTORE_REST - Handle the registers not saved by SAVE_ARGS.
  34  * Gives a full stack frame.
  35  * - ENTRY/END Define functions in the symbol table.
  36  * - FIXUP_TOP_OF_STACK/RESTORE_TOP_OF_STACK - Fix up the hardware stack
  37  * frame that is otherwise undefined after a SYSCALL
  38  * - TRACE_IRQ_* - Trace hard interrupt state for lock debugging.
  39  * - errorentry/paranoidentry/zeroentry - Define exception entry points.
  40  */
  41
  42 #include <linux/linkage.h>
  43 #include <asm/segment.h>
  44 #include <asm/cache.h>
  45 #include <asm/errno.h>
  46 #include <asm/dwarf2.h>
  47 #include <asm/calling.h>
  48 #include <asm/asm-offsets.h>
  49 #include <asm/msr.h>
  50 #include <asm/unistd.h>
  51 #include <asm/thread_info.h>
  52 #include <asm/hw_irq.h>
  53 #include <asm/page_types.h>
  54 #include <asm/irqflags.h>
  55 #include <asm/paravirt.h>
  56 #include <asm/ftrace.h>
  57 #include <asm/percpu.h>
  58
  59 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
  60 #include <linux/elf-em.h>
  61 #define AUDIT_ARCH_X86_64       (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
  62 #define __AUDIT_ARCH_64BIT 0x80000000
  63 #define __AUDIT_ARCH_LE    0x40000000
  64
  65         .code64
  66         .section .entry.text, "ax"
  67
  68 #ifdef CONFIG_FUNCTION_TRACER
  69 #ifdef CONFIG_DYNAMIC_FTRACE
  70 ENTRY(mcount)
  71         retq
  72 END(mcount)
  73
  74 ENTRY(ftrace_caller)
  75         cmpl $0, function_trace_stop
  76         jne  ftrace_stub
  77
  78         MCOUNT_SAVE_FRAME
  79
  80         movq 0x38(%rsp), %rdi
  81         movq 8(%rbp), %rsi
  82         subq $MCOUNT_INSN_SIZE, %rdi
  83
  84 GLOBAL(ftrace_call)
  85         call ftrace_stub
  86
  87         MCOUNT_RESTORE_FRAME
  88
  89 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  90 GLOBAL(ftrace_graph_call)
  91         jmp ftrace_stub
  92 #endif
  93
  94 GLOBAL(ftrace_stub)
  95         retq
  96 END(ftrace_caller)
  97
  98 #else /* ! CONFIG_DYNAMIC_FTRACE */
  99 ENTRY(mcount)
 100         cmpl $0, function_trace_stop
 101         jne  ftrace_stub
 102
 103         cmpq $ftrace_stub, ftrace_trace_function
 104         jnz trace
 105
 106 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 107         cmpq $ftrace_stub, ftrace_graph_return
 108         jnz ftrace_graph_caller
 109
 110         cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
 111         jnz ftrace_graph_caller
 112 #endif
 113
 114 GLOBAL(ftrace_stub)
 115         retq
 116
 117 trace:
 118         MCOUNT_SAVE_FRAME
 119
 120         movq 0x38(%rsp), %rdi
 121         movq 8(%rbp), %rsi
 122         subq $MCOUNT_INSN_SIZE, %rdi
 123
 124         call   *ftrace_trace_function
 125
 126         MCOUNT_RESTORE_FRAME
 127
 128         jmp ftrace_stub
 129 END(mcount)
 130 #endif /* CONFIG_DYNAMIC_FTRACE */
 131 #endif /* CONFIG_FUNCTION_TRACER */
 132
 133 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 134 ENTRY(ftrace_graph_caller)
 135         cmpl $0, function_trace_stop
 136         jne ftrace_stub
 137
 138         MCOUNT_SAVE_FRAME
 139
 140         leaq 8(%rbp), %rdi
 141         movq 0x38(%rsp), %rsi
 142         movq (%rbp), %rdx
 143         subq $MCOUNT_INSN_SIZE, %rsi
 144
 145         call    prepare_ftrace_return
 146
 147         MCOUNT_RESTORE_FRAME
 148
 149         retq
 150 END(ftrace_graph_caller)
 151
 152 GLOBAL(return_to_handler)
 153         subq  $24, %rsp
 154
 155         /* Save the return values */
 156         movq %rax, (%rsp)
 157         movq %rdx, 8(%rsp)
 158         movq %rbp, %rdi
 159
 160         call ftrace_return_to_handler
 161
 162         movq %rax, %rdi
 163         movq 8(%rsp), %rdx
 164         movq (%rsp), %rax
 165         addq $24, %rsp
 166         jmp *%rdi
 167 #endif
 168
 169
 170 #ifndef CONFIG_PREEMPT
 171 #define retint_kernel retint_restore_args
 172 #endif
 173
 174 #ifdef CONFIG_PARAVIRT
 175 ENTRY(native_usergs_sysret64)
 176         swapgs
 177         sysretq
 178 ENDPROC(native_usergs_sysret64)
 179 #endif /* CONFIG_PARAVIRT */
 180
 181
 182 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
 183 #ifdef CONFIG_TRACE_IRQFLAGS
 184         bt   $9,EFLAGS-\offset(%rsp)    /* interrupts off? */
 185         jnc  1f
 186         TRACE_IRQS_ON
 187 1:
 188 #endif
 189 .endm
 190
 191 /*
 192  * C code is not supposed to know about undefined top of stack. Every time
 193  * a C function with an pt_regs argument is called from the SYSCALL based
 194  * fast path FIXUP_TOP_OF_STACK is needed.
 195  * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
 196  * manipulation.
 197  */
 198
 199         /* %rsp:at FRAMEEND */
 200         .macro FIXUP_TOP_OF_STACK tmp offset=0
 201         movq PER_CPU_VAR(old_rsp),\tmp
 202         movq \tmp,RSP+\offset(%rsp)
 203         movq $__USER_DS,SS+\offset(%rsp)
 204         movq $__USER_CS,CS+\offset(%rsp)
 205         movq $-1,RCX+\offset(%rsp)
 206         movq R11+\offset(%rsp),\tmp  /* get eflags */
 207         movq \tmp,EFLAGS+\offset(%rsp)
 208         .endm
 209
 210         .macro RESTORE_TOP_OF_STACK tmp offset=0
 211         movq RSP+\offset(%rsp),\tmp
 212         movq \tmp,PER_CPU_VAR(old_rsp)
 213         movq EFLAGS+\offset(%rsp),\tmp
 214         movq \tmp,R11+\offset(%rsp)
 215         .endm
 216
 217         .macro FAKE_STACK_FRAME child_rip
 218         /* push in order ss, rsp, eflags, cs, rip */
 219         xorl %eax, %eax
 220         pushq_cfi $__KERNEL_DS /* ss */
 221         /*CFI_REL_OFFSET        ss,0*/
 222         pushq_cfi %rax /* rsp */
 223         CFI_REL_OFFSET  rsp,0
 224         pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_BIT1) /* eflags - interrupts on */
 225         /*CFI_REL_OFFSET        rflags,0*/
 226         pushq_cfi $__KERNEL_CS /* cs */
 227         /*CFI_REL_OFFSET        cs,0*/
 228         pushq_cfi \child_rip /* rip */
 229         CFI_REL_OFFSET  rip,0
 230         pushq_cfi %rax /* orig rax */
 231         .endm
 232
 233         .macro UNFAKE_STACK_FRAME
 234         addq $8*6, %rsp
 235         CFI_ADJUST_CFA_OFFSET   -(6*8)
 236         .endm
 237
 238 /*
 239  * initial frame state for interrupts (and exceptions without error code)
 240  */
 241         .macro EMPTY_FRAME start=1 offset=0
 242         .if \start
 243         CFI_STARTPROC simple
 244         CFI_SIGNAL_FRAME
 245         CFI_DEF_CFA rsp,8+\offset
 246         .else
 247         CFI_DEF_CFA_OFFSET 8+\offset
 248         .endif
 249         .endm
 250
 251 /*
 252  * initial frame state for interrupts (and exceptions without error code)
 253  */
 254         .macro INTR_FRAME start=1 offset=0
 255         EMPTY_FRAME \start, SS+8+\offset-RIP
 256         /*CFI_REL_OFFSET ss, SS+\offset-RIP*/
 257         CFI_REL_OFFSET rsp, RSP+\offset-RIP
 258         /*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/
 259         /*CFI_REL_OFFSET cs, CS+\offset-RIP*/
 260         CFI_REL_OFFSET rip, RIP+\offset-RIP
 261         .endm
 262
 263 /*
 264  * initial frame state for exceptions with error code (and interrupts
 265  * with vector already pushed)
 266  */
 267         .macro XCPT_FRAME start=1 offset=0
 268         INTR_FRAME \start, RIP+\offset-ORIG_RAX
 269         /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
 270         .endm
 271
 272 /*
 273  * frame that enables calling into C.
 274  */
 275         .macro PARTIAL_FRAME start=1 offset=0
 276         XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET
 277         CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET
 278         CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET
 279         CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET
 280         CFI_REL_OFFSET rcx, RCX+\offset-ARGOFFSET
 281         CFI_REL_OFFSET rax, RAX+\offset-ARGOFFSET
 282         CFI_REL_OFFSET r8, R8+\offset-ARGOFFSET
 283         CFI_REL_OFFSET r9, R9+\offset-ARGOFFSET
 284         CFI_REL_OFFSET r10, R10+\offset-ARGOFFSET
 285         CFI_REL_OFFSET r11, R11+\offset-ARGOFFSET
 286         .endm
 287
 288 /*
 289  * frame that enables passing a complete pt_regs to a C function.
 290  */
 291         .macro DEFAULT_FRAME start=1 offset=0
 292         PARTIAL_FRAME \start, R11+\offset-R15
 293         CFI_REL_OFFSET rbx, RBX+\offset
 294         CFI_REL_OFFSET rbp, RBP+\offset
 295         CFI_REL_OFFSET r12, R12+\offset
 296         CFI_REL_OFFSET r13, R13+\offset
 297         CFI_REL_OFFSET r14, R14+\offset
 298         CFI_REL_OFFSET r15, R15+\offset
 299         .endm
 300
 301 /* save partial stack frame */
 302         .macro SAVE_ARGS_IRQ
 303         cld
 304         /* start from rbp in pt_regs and jump over */
 305         movq_cfi rdi, RDI-RBP
 306         movq_cfi rsi, RSI-RBP
 307         movq_cfi rdx, RDX-RBP
 308         movq_cfi rcx, RCX-RBP
 309         movq_cfi rax, RAX-RBP
 310         movq_cfi  r8,  R8-RBP
 311         movq_cfi  r9,  R9-RBP
 312         movq_cfi r10, R10-RBP
 313         movq_cfi r11, R11-RBP
 314
 315         /* Save rbp so that we can unwind from get_irq_regs() */
 316         movq_cfi rbp, 0
 317
 318         /* Save previous stack value */
 319         movq %rsp, %rsi
 320
 321         leaq -RBP(%rsp),%rdi    /* arg1 for handler */
 322         testl $3, CS(%rdi)
 323         je 1f
 324         SWAPGS
 325         /*
 326          * irq_count is used to check if a CPU is already on an interrupt stack
 327          * or not. While this is essentially redundant with preempt_count it is
 328          * a little cheaper to use a separate counter in the PDA (short of
 329          * moving irq_enter into assembly, which would be too much work)
 330          */
 331 1:      incl PER_CPU_VAR(irq_count)
 332         jne 2f
 333         mov PER_CPU_VAR(irq_stack_ptr),%rsp
 334         CFI_DEF_CFA_REGISTER    rsi
 335
 336 2:      /* Store previous stack value */
 337         pushq %rsi
 338         CFI_ESCAPE      0x0f /* DW_CFA_def_cfa_expression */, 6, \
 339                         0x77 /* DW_OP_breg7 */, 0, \
 340                         0x06 /* DW_OP_deref */, \
 341                         0x08 /* DW_OP_const1u */, SS+8-RBP, \
 342                         0x22 /* DW_OP_plus */
 343         /* We entered an interrupt context - irqs are off: */
 344         TRACE_IRQS_OFF
 345         .endm
 346
 347 ENTRY(save_rest)
 348         PARTIAL_FRAME 1 REST_SKIP+8
 349         movq 5*8+16(%rsp), %r11 /* save return address */
 350         movq_cfi rbx, RBX+16
 351         movq_cfi rbp, RBP+16
 352         movq_cfi r12, R12+16
 353         movq_cfi r13, R13+16
 354         movq_cfi r14, R14+16
 355         movq_cfi r15, R15+16
 356         movq %r11, 8(%rsp)      /* return address */
 357         FIXUP_TOP_OF_STACK %r11, 16
 358         ret
 359         CFI_ENDPROC
 360 END(save_rest)
 361
 362 /* save complete stack frame */
 363         .pushsection .kprobes.text, "ax"
 364 ENTRY(save_paranoid)
 365         XCPT_FRAME 1 RDI+8
 366         cld
 367         movq_cfi rdi, RDI+8
 368         movq_cfi rsi, RSI+8
 369         movq_cfi rdx, RDX+8
 370         movq_cfi rcx, RCX+8
 371         movq_cfi rax, RAX+8
 372         movq_cfi r8, R8+8
 373         movq_cfi r9, R9+8
 374         movq_cfi r10, R10+8
 375         movq_cfi r11, R11+8
 376         movq_cfi rbx, RBX+8
 377         movq_cfi rbp, RBP+8
 378         movq_cfi r12, R12+8
 379         movq_cfi r13, R13+8
 380         movq_cfi r14, R14+8
 381         movq_cfi r15, R15+8
 382         movl $1,%ebx
 383         movl $MSR_GS_BASE,%ecx
 384         rdmsr
 385         testl %edx,%edx
 386         js 1f   /* negative -> in kernel */
 387         SWAPGS
 388         xorl %ebx,%ebx
 389 1:      ret
 390         CFI_ENDPROC
 391 END(save_paranoid)
 392         .popsection
 393
 394 /*
 395  * A newly forked process directly context switches into this address.
 396  *
 397  * rdi: prev task we switched from
 398  */
 399 ENTRY(ret_from_fork)
 400         DEFAULT_FRAME
 401
 402         LOCK ; btr $TIF_FORK,TI_flags(%r8)
 403
 404         pushq_cfi kernel_eflags(%rip)
 405         popfq_cfi                               # reset kernel eflags
 406
 407         call schedule_tail                      # rdi: 'prev' task parameter
 408
 409         GET_THREAD_INFO(%rcx)
 410
 411         RESTORE_REST
 412
 413         testl $3, CS-ARGOFFSET(%rsp)            # from kernel_thread?
 414         jz   retint_restore_args
 415
 416         testl $_TIF_IA32, TI_flags(%rcx)        # 32-bit compat task needs IRET
 417         jnz  int_ret_from_sys_call
 418
 419         RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
 420         jmp ret_from_sys_call                   # go to the SYSRET fastpath
 421
 422         CFI_ENDPROC
 423 END(ret_from_fork)
 424
 425 /*
 426  * System call entry. Up to 6 arguments in registers are supported.
 427  *
 428  * SYSCALL does not save anything on the stack and does not change the
 429  * stack pointer.
 430  */
 431
 432 /*
 433  * Register setup:
 434  * rax  system call number
 435  * rdi  arg0
 436  * rcx  return address for syscall/sysret, C arg3
 437  * rsi  arg1
 438  * rdx  arg2
 439  * r10  arg3    (--> moved to rcx for C)
 440  * r8   arg4
 441  * r9   arg5
 442  * r11  eflags for syscall/sysret, temporary for C
 443  * r12-r15,rbp,rbx saved by C code, not touched.
 444  *
 445  * Interrupts are off on entry.
 446  * Only called from user space.
 447  *
 448  * XXX  if we had a free scratch register we could save the RSP into the stack frame
 449  *      and report it properly in ps. Unfortunately we haven't.
 450  *
 451  * When user can change the frames always force IRET. That is because
 452  * it deals with uncanonical addresses better. SYSRET has trouble
 453  * with them due to bugs in both AMD and Intel CPUs.
 454  */
 455
 456 ENTRY(system_call)
 457         CFI_STARTPROC   simple
 458         CFI_SIGNAL_FRAME
 459         CFI_DEF_CFA     rsp,KERNEL_STACK_OFFSET
 460         CFI_REGISTER    rip,rcx
 461         /*CFI_REGISTER  rflags,r11*/
 462         SWAPGS_UNSAFE_STACK
 463         /*
 464          * A hypervisor implementation might want to use a label
 465          * after the swapgs, so that it can do the swapgs
 466          * for the guest and jump here on syscall.
 467          */
 468 GLOBAL(system_call_after_swapgs)
 469
 470         movq    %rsp,PER_CPU_VAR(old_rsp)
 471         movq    PER_CPU_VAR(kernel_stack),%rsp
 472         /*
 473          * No need to follow this irqs off/on section - it's straight
 474          * and short:
 475          */
 476         ENABLE_INTERRUPTS(CLBR_NONE)
 477         SAVE_ARGS 8,0
 478         movq  %rax,ORIG_RAX-ARGOFFSET(%rsp)
 479         movq  %rcx,RIP-ARGOFFSET(%rsp)
 480         CFI_REL_OFFSET rip,RIP-ARGOFFSET
 481         testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
 482         jnz tracesys
 483 system_call_fastpath:
 484         cmpq $__NR_syscall_max,%rax
 485         ja badsys
 486         movq %r10,%rcx
 487         call *sys_call_table(,%rax,8)  # XXX:    rip relative
 488         movq %rax,RAX-ARGOFFSET(%rsp)
 489 /*
 490  * Syscall return path ending with SYSRET (fast path)
 491  * Has incomplete stack frame and undefined top of stack.
 492  */
 493 ret_from_sys_call:
 494         movl $_TIF_ALLWORK_MASK,%edi
 495         /* edi: flagmask */
 496 sysret_check:
 497         LOCKDEP_SYS_EXIT
 498         DISABLE_INTERRUPTS(CLBR_NONE)
 499         TRACE_IRQS_OFF
 500         movl TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET),%edx
 501         andl %edi,%edx
 502         jnz  sysret_careful
 503         CFI_REMEMBER_STATE
 504         /*
 505          * sysretq will re-enable interrupts:
 506          */
 507         TRACE_IRQS_ON
 508         movq RIP-ARGOFFSET(%rsp),%rcx
 509         CFI_REGISTER    rip,rcx
 510         RESTORE_ARGS 1,-ARG_SKIP,0
 511         /*CFI_REGISTER  rflags,r11*/
 512         movq    PER_CPU_VAR(old_rsp), %rsp
 513         USERGS_SYSRET64
 514
 515         CFI_RESTORE_STATE
 516         /* Handle reschedules */
 517         /* edx: work, edi: workmask */
 518 sysret_careful:
 519         bt $TIF_NEED_RESCHED,%edx
 520         jnc sysret_signal
 521         TRACE_IRQS_ON
 522         ENABLE_INTERRUPTS(CLBR_NONE)
 523         pushq_cfi %rdi
 524         call schedule
 525         popq_cfi %rdi
 526         jmp sysret_check
 527
 528         /* Handle a signal */
 529 sysret_signal:
 530         TRACE_IRQS_ON
 531         ENABLE_INTERRUPTS(CLBR_NONE)
 532 #ifdef CONFIG_AUDITSYSCALL
 533         bt $TIF_SYSCALL_AUDIT,%edx
 534         jc sysret_audit
 535 #endif
 536         /*
 537          * We have a signal, or exit tracing or single-step.
 538          * These all wind up with the iret return path anyway,
 539          * so just join that path right now.
 540          */
 541         FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
 542         jmp int_check_syscall_exit_work
 543
 544 badsys:
 545         movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
 546         jmp ret_from_sys_call
 547
 548 #ifdef CONFIG_AUDITSYSCALL
 549         /*
 550          * Fast path for syscall audit without full syscall trace.
 551          * We just call audit_syscall_entry() directly, and then
 552          * jump back to the normal fast path.
 553          */
 554 auditsys:
 555         movq %r10,%r9                   /* 6th arg: 4th syscall arg */
 556         movq %rdx,%r8                   /* 5th arg: 3rd syscall arg */
 557         movq %rsi,%rcx                  /* 4th arg: 2nd syscall arg */
 558         movq %rdi,%rdx                  /* 3rd arg: 1st syscall arg */
 559         movq %rax,%rsi                  /* 2nd arg: syscall number */
 560         movl $AUDIT_ARCH_X86_64,%edi    /* 1st arg: audit arch */
 561         call audit_syscall_entry
 562         LOAD_ARGS 0             /* reload call-clobbered registers */
 563         jmp system_call_fastpath
 564
 565         /*
 566          * Return fast path for syscall audit.  Call audit_syscall_exit()
 567          * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
 568          * masked off.
 569          */
 570 sysret_audit:
 571         movq RAX-ARGOFFSET(%rsp),%rsi   /* second arg, syscall return value */
 572         cmpq $0,%rsi            /* is it < 0? */
 573         setl %al                /* 1 if so, 0 if not */
 574         movzbl %al,%edi         /* zero-extend that into %edi */
 575         inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
 576         call audit_syscall_exit
 577         movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
 578         jmp sysret_check
 579 #endif  /* CONFIG_AUDITSYSCALL */
 580
 581         /* Do syscall tracing */
 582 tracesys:
 583 #ifdef CONFIG_AUDITSYSCALL
 584         testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
 585         jz auditsys
 586 #endif
 587         SAVE_REST
 588         movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
 589         FIXUP_TOP_OF_STACK %rdi
 590         movq %rsp,%rdi
 591         call syscall_trace_enter
 592         /*
 593          * Reload arg registers from stack in case ptrace changed them.
 594          * We don't reload %rax because syscall_trace_enter() returned
 595          * the value it wants us to use in the table lookup.
 596          */
 597         LOAD_ARGS ARGOFFSET, 1
 598         RESTORE_REST
 599         cmpq $__NR_syscall_max,%rax
 600         ja   int_ret_from_sys_call      /* RAX(%rsp) set to -ENOSYS above */
 601         movq %r10,%rcx  /* fixup for C */
 602         call *sys_call_table(,%rax,8)
 603         movq %rax,RAX-ARGOFFSET(%rsp)
 604         /* Use IRET because user could have changed frame */
 605
 606 /*
 607  * Syscall return path ending with IRET.
 608  * Has correct top of stack, but partial stack frame.
 609  */
 610 GLOBAL(int_ret_from_sys_call)
 611         DISABLE_INTERRUPTS(CLBR_NONE)
 612         TRACE_IRQS_OFF
 613         movl $_TIF_ALLWORK_MASK,%edi
 614         /* edi: mask to check */
 615 GLOBAL(int_with_check)
 616         LOCKDEP_SYS_EXIT_IRQ
 617         GET_THREAD_INFO(%rcx)
 618         movl TI_flags(%rcx),%edx
 619         andl %edi,%edx
 620         jnz   int_careful
 621         andl    $~TS_COMPAT,TI_status(%rcx)
 622         jmp   retint_swapgs
 623
 624         /* Either reschedule or signal or syscall exit tracking needed. */
 625         /* First do a reschedule test. */
 626         /* edx: work, edi: workmask */
 627 int_careful:
 628         bt $TIF_NEED_RESCHED,%edx
 629         jnc  int_very_careful
 630         TRACE_IRQS_ON
 631         ENABLE_INTERRUPTS(CLBR_NONE)
 632         pushq_cfi %rdi
 633         call schedule
 634         popq_cfi %rdi
 635         DISABLE_INTERRUPTS(CLBR_NONE)
 636         TRACE_IRQS_OFF
 637         jmp int_with_check
 638
 639         /* handle signals and tracing -- both require a full stack frame */
 640 int_very_careful:
 641         TRACE_IRQS_ON
 642         ENABLE_INTERRUPTS(CLBR_NONE)
 643 int_check_syscall_exit_work:
 644         SAVE_REST
 645         /* Check for syscall exit trace */
 646         testl $_TIF_WORK_SYSCALL_EXIT,%edx
 647         jz int_signal
 648         pushq_cfi %rdi
 649         leaq 8(%rsp),%rdi       # &ptregs -> arg1
 650         call syscall_trace_leave
 651         popq_cfi %rdi
 652         andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
 653         jmp int_restore_rest
 654
 655 int_signal:
 656         testl $_TIF_DO_NOTIFY_MASK,%edx
 657         jz 1f
 658         movq %rsp,%rdi          # &ptregs -> arg1
 659         xorl %esi,%esi          # oldset -> arg2
 660         call do_notify_resume
 661 1:      movl $_TIF_WORK_MASK,%edi
 662 int_restore_rest:
 663         RESTORE_REST
 664         DISABLE_INTERRUPTS(CLBR_NONE)
 665         TRACE_IRQS_OFF
 666         jmp int_with_check
 667         CFI_ENDPROC
 668 END(system_call)
 669
 670 /*
 671  * Certain special system calls that need to save a complete full stack frame.
 672  */
 673         .macro PTREGSCALL label,func,arg
 674 ENTRY(\label)
 675         PARTIAL_FRAME 1 8               /* offset 8: return address */
 676         subq $REST_SKIP, %rsp
 677         CFI_ADJUST_CFA_OFFSET REST_SKIP
 678         call save_rest
 679         DEFAULT_FRAME 0 8               /* offset 8: return address */
 680         leaq 8(%rsp), \arg      /* pt_regs pointer */
 681         call \func
 682         jmp ptregscall_common
 683         CFI_ENDPROC
 684 END(\label)
 685         .endm
 686
 687         PTREGSCALL stub_clone, sys_clone, %r8
 688         PTREGSCALL stub_fork, sys_fork, %rdi
 689         PTREGSCALL stub_vfork, sys_vfork, %rdi
 690         PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
 691         PTREGSCALL stub_iopl, sys_iopl, %rsi
 692
 693 ENTRY(ptregscall_common)
 694         DEFAULT_FRAME 1 8       /* offset 8: return address */
 695         RESTORE_TOP_OF_STACK %r11, 8
 696         movq_cfi_restore R15+8, r15
 697         movq_cfi_restore R14+8, r14
 698         movq_cfi_restore R13+8, r13
 699         movq_cfi_restore R12+8, r12
 700         movq_cfi_restore RBP+8, rbp
 701         movq_cfi_restore RBX+8, rbx
 702         ret $REST_SKIP          /* pop extended registers */
 703         CFI_ENDPROC
 704 END(ptregscall_common)
 705
 706 ENTRY(stub_execve)
 707         CFI_STARTPROC
 708         addq $8, %rsp
 709         PARTIAL_FRAME 0
 710         SAVE_REST
 711         FIXUP_TOP_OF_STACK %r11
 712         movq %rsp, %rcx
 713         call sys_execve
 714         RESTORE_TOP_OF_STACK %r11
 715         movq %rax,RAX(%rsp)
 716         RESTORE_REST
 717         jmp int_ret_from_sys_call
 718         CFI_ENDPROC
 719 END(stub_execve)
 720
 721 /*
 722  * sigreturn is special because it needs to restore all registers on return.
 723  * This cannot be done with SYSRET, so use the IRET return path instead.
 724  */
 725 ENTRY(stub_rt_sigreturn)
 726         CFI_STARTPROC
 727         addq $8, %rsp
 728         PARTIAL_FRAME 0
 729         SAVE_REST
 730         movq %rsp,%rdi
 731         FIXUP_TOP_OF_STACK %r11
 732         call sys_rt_sigreturn
 733         movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
 734         RESTORE_REST
 735         jmp int_ret_from_sys_call
 736         CFI_ENDPROC
 737 END(stub_rt_sigreturn)
 738
 739 /*
 740  * Build the entry stubs and pointer table with some assembler magic.
 741  * We pack 7 stubs into a single 32-byte chunk, which will fit in a
 742  * single cache line on all modern x86 implementations.
 743  */
 744         .section .init.rodata,"a"
 745 ENTRY(interrupt)
 746         .section .entry.text
 747         .p2align 5
 748         .p2align CONFIG_X86_L1_CACHE_SHIFT
 749 ENTRY(irq_entries_start)
 750         INTR_FRAME
 751 vector=FIRST_EXTERNAL_VECTOR
 752 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
 753         .balign 32
 754   .rept 7
 755     .if vector < NR_VECTORS
 756       .if vector <> FIRST_EXTERNAL_VECTOR
 757         CFI_ADJUST_CFA_OFFSET -8
 758       .endif
 759 1:      pushq_cfi $(~vector+0x80)       /* Note: always in signed byte range */
 760       .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
 761         jmp 2f
 762       .endif
 763       .previous
 764         .quad 1b
 765       .section .entry.text
 766 vector=vector+1
 767     .endif
 768   .endr
 769 2:      jmp common_interrupt
 770 .endr
 771         CFI_ENDPROC
 772 END(irq_entries_start)
 773
 774 .previous
 775 END(interrupt)
 776 .previous
 777
 778 /*
 779  * Interrupt entry/exit.
 780  *
 781  * Interrupt entry points save only callee clobbered registers in fast path.
 782  *
 783  * Entry runs with interrupts off.
 784  */
 785
 786 /* 0(%rsp): ~(interrupt number) */
 787         .macro interrupt func
 788         /* reserve pt_regs for scratch regs and rbp */
 789         subq $ORIG_RAX-RBP, %rsp
 790         CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP
 791         SAVE_ARGS_IRQ
 792         call \func
 793         .endm
 794
 795 /*
 796  * Interrupt entry/exit should be protected against kprobes
 797  */
 798         .pushsection .kprobes.text, "ax"
 799         /*
 800          * The interrupt stubs push (~vector+0x80) onto the stack and
 801          * then jump to common_interrupt.
 802          */
 803         .p2align CONFIG_X86_L1_CACHE_SHIFT
 804 common_interrupt:
 805         XCPT_FRAME
 806         addq $-0x80,(%rsp)              /* Adjust vector to [-256,-1] range */
 807         interrupt do_IRQ
 808         /* 0(%rsp): old_rsp-ARGOFFSET */
 809 ret_from_intr:
 810         DISABLE_INTERRUPTS(CLBR_NONE)
 811         TRACE_IRQS_OFF
 812         decl PER_CPU_VAR(irq_count)
 813
 814         /* Restore saved previous stack */
 815         popq %rsi
 816         CFI_DEF_CFA_REGISTER    rsi
 817         leaq ARGOFFSET-RBP(%rsi), %rsp
 818         CFI_DEF_CFA_REGISTER    rsp
 819         CFI_ADJUST_CFA_OFFSET   RBP-ARGOFFSET
 820
 821 exit_intr:
 822         GET_THREAD_INFO(%rcx)
 823         testl $3,CS-ARGOFFSET(%rsp)
 824         je retint_kernel
 825
 826         /* Interrupt came from user space */
 827         /*
 828          * Has a correct top of stack, but a partial stack frame
 829          * %rcx: thread info. Interrupts off.
 830          */
 831 retint_with_reschedule:
 832         movl $_TIF_WORK_MASK,%edi
 833 retint_check:
 834         LOCKDEP_SYS_EXIT_IRQ
 835         movl TI_flags(%rcx),%edx
 836         andl %edi,%edx
 837         CFI_REMEMBER_STATE
 838         jnz  retint_careful
 839
 840 retint_swapgs:          /* return to user-space */
 841         /*
 842          * The iretq could re-enable interrupts:
 843          */
 844         DISABLE_INTERRUPTS(CLBR_ANY)
 845         TRACE_IRQS_IRETQ
 846         SWAPGS
 847         jmp restore_args
 848
 849 retint_restore_args:    /* return to kernel space */
 850         DISABLE_INTERRUPTS(CLBR_ANY)
 851         /*
 852          * The iretq could re-enable interrupts:
 853          */
 854         TRACE_IRQS_IRETQ
 855 restore_args:
 856         RESTORE_ARGS 1,8,1
 857
 858 irq_return:
 859         INTERRUPT_RETURN
 860
 861         .section __ex_table, "a"
 862         .quad irq_return, bad_iret
 863         .previous
 864
 865 #ifdef CONFIG_PARAVIRT
 866 ENTRY(native_iret)
 867         iretq
 868
 869         .section __ex_table,"a"
 870         .quad native_iret, bad_iret
 871         .previous
 872 #endif
 873
 874         .section .fixup,"ax"
 875 bad_iret:
 876         /*
 877          * The iret traps when the %cs or %ss being restored is bogus.
 878          * We've lost the original trap vector and error code.
 879          * #GPF is the most likely one to get for an invalid selector.
 880          * So pretend we completed the iret and took the #GPF in user mode.
 881          *
 882          * We are now running with the kernel GS after exception recovery.
 883          * But error_entry expects us to have user GS to match the user %cs,
 884          * so swap back.
 885          */
 886         pushq $0
 887
 888         SWAPGS
 889         jmp general_protection
 890
 891         .previous
 892
 893         /* edi: workmask, edx: work */
 894 retint_careful:
 895         CFI_RESTORE_STATE
 896         bt    $TIF_NEED_RESCHED,%edx
 897         jnc   retint_signal
 898         TRACE_IRQS_ON
 899         ENABLE_INTERRUPTS(CLBR_NONE)
 900         pushq_cfi %rdi
 901         call  schedule
 902         popq_cfi %rdi
 903         GET_THREAD_INFO(%rcx)
 904         DISABLE_INTERRUPTS(CLBR_NONE)
 905         TRACE_IRQS_OFF
 906         jmp retint_check
 907
 908 retint_signal:
 909         testl $_TIF_DO_NOTIFY_MASK,%edx
 910         jz    retint_swapgs
 911         TRACE_IRQS_ON
 912         ENABLE_INTERRUPTS(CLBR_NONE)
 913         SAVE_REST
 914         movq $-1,ORIG_RAX(%rsp)
 915         xorl %esi,%esi          # oldset
 916         movq %rsp,%rdi          # &pt_regs
 917         call do_notify_resume
 918         RESTORE_REST
 919         DISABLE_INTERRUPTS(CLBR_NONE)
 920         TRACE_IRQS_OFF
 921         GET_THREAD_INFO(%rcx)
 922         jmp retint_with_reschedule
 923
 924 #ifdef CONFIG_PREEMPT
 925         /* Returning to kernel space. Check if we need preemption */
 926         /* rcx:  threadinfo. interrupts off. */
 927 ENTRY(retint_kernel)
 928         cmpl $0,TI_preempt_count(%rcx)
 929         jnz  retint_restore_args
 930         bt  $TIF_NEED_RESCHED,TI_flags(%rcx)
 931         jnc  retint_restore_args
 932         bt   $9,EFLAGS-ARGOFFSET(%rsp)  /* interrupts off? */
 933         jnc  retint_restore_args
 934         call preempt_schedule_irq
 935         jmp exit_intr
 936 #endif
 937
 938         CFI_ENDPROC
 939 END(common_interrupt)
 940 /*
 941  * End of kprobes section
 942  */
 943        .popsection
 944
 945 /*
 946  * APIC interrupts.
 947  */
 948 .macro apicinterrupt num sym do_sym
 949 ENTRY(\sym)
 950         INTR_FRAME
 951         pushq_cfi $~(\num)
 952 .Lcommon_\sym:
 953         interrupt \do_sym
 954         jmp ret_from_intr
 955         CFI_ENDPROC
 956 END(\sym)
 957 .endm
 958
 959 #ifdef CONFIG_SMP
 960 apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \
 961         irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt
 962 apicinterrupt REBOOT_VECTOR \
 963         reboot_interrupt smp_reboot_interrupt
 964 #endif
 965
 966 #ifdef CONFIG_X86_UV
 967 apicinterrupt UV_BAU_MESSAGE \
 968         uv_bau_message_intr1 uv_bau_message_interrupt
 969 #endif
 970 apicinterrupt LOCAL_TIMER_VECTOR \
 971         apic_timer_interrupt smp_apic_timer_interrupt
 972 apicinterrupt X86_PLATFORM_IPI_VECTOR \
 973         x86_platform_ipi smp_x86_platform_ipi
 974
 975 #ifdef CONFIG_SMP
 976         ALIGN
 977         INTR_FRAME
 978 .irp idx,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \
 979         16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
 980 .if NUM_INVALIDATE_TLB_VECTORS > \idx
 981 ENTRY(invalidate_interrupt\idx)
 982         pushq_cfi $~(INVALIDATE_TLB_VECTOR_START+\idx)
 983         jmp .Lcommon_invalidate_interrupt0
 984         CFI_ADJUST_CFA_OFFSET -8
 985 END(invalidate_interrupt\idx)
 986 .endif
 987 .endr
 988         CFI_ENDPROC
 989 apicinterrupt INVALIDATE_TLB_VECTOR_START, \
 990         invalidate_interrupt0, smp_invalidate_interrupt
 991 #endif
 992
 993 apicinterrupt THRESHOLD_APIC_VECTOR \
 994         threshold_interrupt smp_threshold_interrupt
 995 apicinterrupt THERMAL_APIC_VECTOR \
 996         thermal_interrupt smp_thermal_interrupt
 997
 998 #ifdef CONFIG_SMP
 999 apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \
1000         call_function_single_interrupt smp_call_function_single_interrupt
1001 apicinterrupt CALL_FUNCTION_VECTOR \
1002         call_function_interrupt smp_call_function_interrupt
1003 apicinterrupt RESCHEDULE_VECTOR \
1004         reschedule_interrupt smp_reschedule_interrupt
1005 #endif
1006
1007 apicinterrupt ERROR_APIC_VECTOR \
1008         error_interrupt smp_error_interrupt
1009 apicinterrupt SPURIOUS_APIC_VECTOR \
1010         spurious_interrupt smp_spurious_interrupt
1011
1012 #ifdef CONFIG_IRQ_WORK
1013 apicinterrupt IRQ_WORK_VECTOR \
1014         irq_work_interrupt smp_irq_work_interrupt
1015 #endif
1016
1017 /*
1018  * Exception entry points.
1019  */
1020 .macro zeroentry sym do_sym
1021 ENTRY(\sym)
1022         INTR_FRAME
1023         PARAVIRT_ADJUST_EXCEPTION_FRAME
1024         pushq_cfi $-1           /* ORIG_RAX: no syscall to restart */
1025         subq $ORIG_RAX-R15, %rsp
1026         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1027         call error_entry
1028         DEFAULT_FRAME 0
1029         movq %rsp,%rdi          /* pt_regs pointer */
1030         xorl %esi,%esi          /* no error code */
1031         call \do_sym
1032         jmp error_exit          /* %ebx: no swapgs flag */
1033         CFI_ENDPROC
1034 END(\sym)
1035 .endm
1036
1037 .macro paranoidzeroentry sym do_sym
1038 ENTRY(\sym)
1039         INTR_FRAME
1040         PARAVIRT_ADJUST_EXCEPTION_FRAME
1041         pushq_cfi $-1           /* ORIG_RAX: no syscall to restart */
1042         subq $ORIG_RAX-R15, %rsp
1043         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1044         call save_paranoid
1045         TRACE_IRQS_OFF
1046         movq %rsp,%rdi          /* pt_regs pointer */
1047         xorl %esi,%esi          /* no error code */
1048         call \do_sym
1049         jmp paranoid_exit       /* %ebx: no swapgs flag */
1050         CFI_ENDPROC
1051 END(\sym)
1052 .endm
1053
1054 #define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
1055 .macro paranoidzeroentry_ist sym do_sym ist
1056 ENTRY(\sym)
1057         INTR_FRAME
1058         PARAVIRT_ADJUST_EXCEPTION_FRAME
1059         pushq_cfi $-1           /* ORIG_RAX: no syscall to restart */
1060         subq $ORIG_RAX-R15, %rsp
1061         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1062         call save_paranoid
1063         TRACE_IRQS_OFF
1064         movq %rsp,%rdi          /* pt_regs pointer */
1065         xorl %esi,%esi          /* no error code */
1066         subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1067         call \do_sym
1068         addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1069         jmp paranoid_exit       /* %ebx: no swapgs flag */
1070         CFI_ENDPROC
1071 END(\sym)
1072 .endm
1073
1074 .macro errorentry sym do_sym
1075 ENTRY(\sym)
1076         XCPT_FRAME
1077         PARAVIRT_ADJUST_EXCEPTION_FRAME
1078         subq $ORIG_RAX-R15, %rsp
1079         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1080         call error_entry
1081         DEFAULT_FRAME 0
1082         movq %rsp,%rdi                  /* pt_regs pointer */
1083         movq ORIG_RAX(%rsp),%rsi        /* get error code */
1084         movq $-1,ORIG_RAX(%rsp)         /* no syscall to restart */
1085         call \do_sym
1086         jmp error_exit                  /* %ebx: no swapgs flag */
1087         CFI_ENDPROC
1088 END(\sym)
1089 .endm
1090
1091         /* error code is on the stack already */
1092 .macro paranoiderrorentry sym do_sym
1093 ENTRY(\sym)
1094         XCPT_FRAME
1095         PARAVIRT_ADJUST_EXCEPTION_FRAME
1096         subq $ORIG_RAX-R15, %rsp
1097         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1098         call save_paranoid
1099         DEFAULT_FRAME 0
1100         TRACE_IRQS_OFF
1101         movq %rsp,%rdi                  /* pt_regs pointer */
1102         movq ORIG_RAX(%rsp),%rsi        /* get error code */
1103         movq $-1,ORIG_RAX(%rsp)         /* no syscall to restart */
1104         call \do_sym
1105         jmp paranoid_exit               /* %ebx: no swapgs flag */
1106         CFI_ENDPROC
1107 END(\sym)
1108 .endm
1109
1110 zeroentry divide_error do_divide_error
1111 zeroentry overflow do_overflow
1112 zeroentry bounds do_bounds
1113 zeroentry invalid_op do_invalid_op
1114 zeroentry device_not_available do_device_not_available
1115 paranoiderrorentry double_fault do_double_fault
1116 zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun
1117 errorentry invalid_TSS do_invalid_TSS
1118 errorentry segment_not_present do_segment_not_present
1119 zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
1120 zeroentry coprocessor_error do_coprocessor_error
1121 errorentry alignment_check do_alignment_check
1122 zeroentry simd_coprocessor_error do_simd_coprocessor_error
1123
1124
1125         /* Reload gs selector with exception handling */
1126         /* edi:  new selector */
1127 ENTRY(native_load_gs_index)
1128         CFI_STARTPROC
1129         pushfq_cfi
1130         DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
1131         SWAPGS
1132 gs_change:
1133         movl %edi,%gs
1134 2:      mfence          /* workaround */
1135         SWAPGS
1136         popfq_cfi
1137         ret
1138         CFI_ENDPROC
1139 END(native_load_gs_index)
1140
1141         .section __ex_table,"a"
1142         .align 8
1143         .quad gs_change,bad_gs
1144         .previous
1145         .section .fixup,"ax"
1146         /* running with kernelgs */
1147 bad_gs:
1148         SWAPGS                  /* switch back to user gs */
1149         xorl %eax,%eax
1150         movl %eax,%gs
1151         jmp  2b
1152         .previous
1153
1154 ENTRY(kernel_thread_helper)
1155         pushq $0                # fake return address
1156         CFI_STARTPROC
1157         /*
1158          * Here we are in the child and the registers are set as they were
1159          * at kernel_thread() invocation in the parent.
1160          */
1161         call *%rsi
1162         # exit
1163         mov %eax, %edi
1164         call do_exit
1165         ud2                     # padding for call trace
1166         CFI_ENDPROC
1167 END(kernel_thread_helper)
1168
1169 /*
1170  * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
1171  *
1172  * C extern interface:
1173  *       extern long execve(const char *name, char **argv, char **envp)
1174  *
1175  * asm input arguments:
1176  *      rdi: name, rsi: argv, rdx: envp
1177  *
1178  * We want to fallback into:
1179  *      extern long sys_execve(const char *name, char **argv,char **envp, struct pt_regs *regs)
1180  *
1181  * do_sys_execve asm fallback arguments:
1182  *      rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
1183  */
1184 ENTRY(kernel_execve)
1185         CFI_STARTPROC
1186         FAKE_STACK_FRAME $0
1187         SAVE_ALL
1188         movq %rsp,%rcx
1189         call sys_execve
1190         movq %rax, RAX(%rsp)
1191         RESTORE_REST
1192         testq %rax,%rax
1193         je int_ret_from_sys_call
1194         RESTORE_ARGS
1195         UNFAKE_STACK_FRAME
1196         ret
1197         CFI_ENDPROC
1198 END(kernel_execve)
1199
1200 /* Call softirq on interrupt stack. Interrupts are off. */
1201 ENTRY(call_softirq)
1202         CFI_STARTPROC
1203         pushq_cfi %rbp
1204         CFI_REL_OFFSET rbp,0
1205         mov  %rsp,%rbp
1206         CFI_DEF_CFA_REGISTER rbp
1207         incl PER_CPU_VAR(irq_count)
1208         cmove PER_CPU_VAR(irq_stack_ptr),%rsp
1209         push  %rbp                      # backlink for old unwinder
1210         call __do_softirq
1211         leaveq
1212         CFI_RESTORE             rbp
1213         CFI_DEF_CFA_REGISTER    rsp
1214         CFI_ADJUST_CFA_OFFSET   -8
1215         decl PER_CPU_VAR(irq_count)
1216         ret
1217         CFI_ENDPROC
1218 END(call_softirq)
1219
1220 #ifdef CONFIG_XEN
1221 zeroentry xen_hypervisor_callback xen_do_hypervisor_callback
1222
1223 /*
1224  * A note on the "critical region" in our callback handler.
1225  * We want to avoid stacking callback handlers due to events occurring
1226  * during handling of the last event. To do this, we keep events disabled
1227  * until we've done all processing. HOWEVER, we must enable events before
1228  * popping the stack frame (can't be done atomically) and so it would still
1229  * be possible to get enough handler activations to overflow the stack.
1230  * Although unlikely, bugs of that kind are hard to track down, so we'd
1231  * like to avoid the possibility.
1232  * So, on entry to the handler we detect whether we interrupted an
1233  * existing activation in its critical region -- if so, we pop the current
1234  * activation and restart the handler using the previous one.
1235  */
1236 ENTRY(xen_do_hypervisor_callback)   # do_hypervisor_callback(struct *pt_regs)
1237         CFI_STARTPROC
1238 /*
1239  * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
1240  * see the correct pointer to the pt_regs
1241  */
1242         movq %rdi, %rsp            # we don't return, adjust the stack frame
1243         CFI_ENDPROC
1244         DEFAULT_FRAME
1245 11:     incl PER_CPU_VAR(irq_count)
1246         movq %rsp,%rbp
1247         CFI_DEF_CFA_REGISTER rbp
1248         cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
1249         pushq %rbp                      # backlink for old unwinder
1250         call xen_evtchn_do_upcall
1251         popq %rsp
1252         CFI_DEF_CFA_REGISTER rsp
1253         decl PER_CPU_VAR(irq_count)
1254         jmp  error_exit
1255         CFI_ENDPROC
1256 END(xen_do_hypervisor_callback)
1257
1258 /*
1259  * Hypervisor uses this for application faults while it executes.
1260  * We get here for two reasons:
1261  *  1. Fault while reloading DS, ES, FS or GS
1262  *  2. Fault while executing IRET
1263  * Category 1 we do not need to fix up as Xen has already reloaded all segment
1264  * registers that could be reloaded and zeroed the others.
1265  * Category 2 we fix up by killing the current process. We cannot use the
1266  * normal Linux return path in this case because if we use the IRET hypercall
1267  * to pop the stack frame we end up in an infinite loop of failsafe callbacks.
1268  * We distinguish between categories by comparing each saved segment register
1269  * with its current contents: any discrepancy means we in category 1.
1270  */
1271 ENTRY(xen_failsafe_callback)
1272         INTR_FRAME 1 (6*8)
1273         /*CFI_REL_OFFSET gs,GS*/
1274         /*CFI_REL_OFFSET fs,FS*/
1275         /*CFI_REL_OFFSET es,ES*/
1276         /*CFI_REL_OFFSET ds,DS*/
1277         CFI_REL_OFFSET r11,8
1278         CFI_REL_OFFSET rcx,0
1279         movw %ds,%cx
1280         cmpw %cx,0x10(%rsp)
1281         CFI_REMEMBER_STATE
1282         jne 1f
1283         movw %es,%cx
1284         cmpw %cx,0x18(%rsp)
1285         jne 1f
1286         movw %fs,%cx
1287         cmpw %cx,0x20(%rsp)
1288         jne 1f
1289         movw %gs,%cx
1290         cmpw %cx,0x28(%rsp)
1291         jne 1f
1292         /* All segments match their saved values => Category 2 (Bad IRET). */
1293         movq (%rsp),%rcx
1294         CFI_RESTORE rcx
1295         movq 8(%rsp),%r11
1296         CFI_RESTORE r11
1297         addq $0x30,%rsp
1298         CFI_ADJUST_CFA_OFFSET -0x30
1299         pushq_cfi $0    /* RIP */
1300         pushq_cfi %r11
1301         pushq_cfi %rcx
1302         jmp general_protection
1303         CFI_RESTORE_STATE
1304 1:      /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
1305         movq (%rsp),%rcx
1306         CFI_RESTORE rcx
1307         movq 8(%rsp),%r11
1308         CFI_RESTORE r11
1309         addq $0x30,%rsp
1310         CFI_ADJUST_CFA_OFFSET -0x30
1311         pushq_cfi $0
1312         SAVE_ALL
1313         jmp error_exit
1314         CFI_ENDPROC
1315 END(xen_failsafe_callback)
1316
1317 apicinterrupt XEN_HVM_EVTCHN_CALLBACK \
1318         xen_hvm_callback_vector xen_evtchn_do_upcall
1319
1320 #endif /* CONFIG_XEN */
1321
1322 /*
1323  * Some functions should be protected against kprobes
1324  */
1325         .pushsection .kprobes.text, "ax"
1326
1327 paranoidzeroentry_ist debug do_debug DEBUG_STACK
1328 paranoidzeroentry_ist int3 do_int3 DEBUG_STACK
1329 paranoiderrorentry stack_segment do_stack_segment
1330 #ifdef CONFIG_XEN
1331 zeroentry xen_debug do_debug
1332 zeroentry xen_int3 do_int3
1333 errorentry xen_stack_segment do_stack_segment
1334 #endif
1335 errorentry general_protection do_general_protection
1336 errorentry page_fault do_page_fault
1337 #ifdef CONFIG_KVM_GUEST
1338 errorentry async_page_fault do_async_page_fault
1339 #endif
1340 #ifdef CONFIG_X86_MCE
1341 paranoidzeroentry machine_check *machine_check_vector(%rip)
1342 #endif
1343
1344         /*
1345          * "Paranoid" exit path from exception stack.
1346          * Paranoid because this is used by NMIs and cannot take
1347          * any kernel state for granted.
1348          * We don't do kernel preemption checks here, because only
1349          * NMI should be common and it does not enable IRQs and
1350          * cannot get reschedule ticks.
1351          *
1352          * "trace" is 0 for the NMI handler only, because irq-tracing
1353          * is fundamentally NMI-unsafe. (we cannot change the soft and
1354          * hard flags at once, atomically)
1355          */
1356
1357         /* ebx: no swapgs flag */
1358 ENTRY(paranoid_exit)
1359         DEFAULT_FRAME
1360         DISABLE_INTERRUPTS(CLBR_NONE)
1361         TRACE_IRQS_OFF
1362         testl %ebx,%ebx                         /* swapgs needed? */
1363         jnz paranoid_restore
1364         testl $3,CS(%rsp)
1365         jnz   paranoid_userspace
1366 paranoid_swapgs:
1367         TRACE_IRQS_IRETQ 0
1368         SWAPGS_UNSAFE_STACK
1369         RESTORE_ALL 8
1370         jmp irq_return
1371 paranoid_restore:
1372         TRACE_IRQS_IRETQ 0
1373         RESTORE_ALL 8
1374         jmp irq_return
1375 paranoid_userspace:
1376         GET_THREAD_INFO(%rcx)
1377         movl TI_flags(%rcx),%ebx
1378         andl $_TIF_WORK_MASK,%ebx
1379         jz paranoid_swapgs
1380         movq %rsp,%rdi                  /* &pt_regs */
1381         call sync_regs
1382         movq %rax,%rsp                  /* switch stack for scheduling */
1383         testl $_TIF_NEED_RESCHED,%ebx
1384         jnz paranoid_schedule
1385         movl %ebx,%edx                  /* arg3: thread flags */
1386         TRACE_IRQS_ON
1387         ENABLE_INTERRUPTS(CLBR_NONE)
1388         xorl %esi,%esi                  /* arg2: oldset */
1389         movq %rsp,%rdi                  /* arg1: &pt_regs */
1390         call do_notify_resume
1391         DISABLE_INTERRUPTS(CLBR_NONE)
1392         TRACE_IRQS_OFF
1393         jmp paranoid_userspace
1394 paranoid_schedule:
1395         TRACE_IRQS_ON
1396         ENABLE_INTERRUPTS(CLBR_ANY)
1397         call schedule
1398         DISABLE_INTERRUPTS(CLBR_ANY)
1399         TRACE_IRQS_OFF
1400         jmp paranoid_userspace
1401         CFI_ENDPROC
1402 END(paranoid_exit)
1403
1404 /*
1405  * Exception entry point. This expects an error code/orig_rax on the stack.
1406  * returns in "no swapgs flag" in %ebx.
1407  */
1408 ENTRY(error_entry)
1409         XCPT_FRAME
1410         CFI_ADJUST_CFA_OFFSET 15*8
1411         /* oldrax contains error code */
1412         cld
1413         movq_cfi rdi, RDI+8
1414         movq_cfi rsi, RSI+8
1415         movq_cfi rdx, RDX+8
1416         movq_cfi rcx, RCX+8
1417         movq_cfi rax, RAX+8
1418         movq_cfi  r8,  R8+8
1419         movq_cfi  r9,  R9+8
1420         movq_cfi r10, R10+8
1421         movq_cfi r11, R11+8
1422         movq_cfi rbx, RBX+8
1423         movq_cfi rbp, RBP+8
1424         movq_cfi r12, R12+8
1425         movq_cfi r13, R13+8
1426         movq_cfi r14, R14+8
1427         movq_cfi r15, R15+8
1428         xorl %ebx,%ebx
1429         testl $3,CS+8(%rsp)
1430         je error_kernelspace
1431 error_swapgs:
1432         SWAPGS
1433 error_sti:
1434         TRACE_IRQS_OFF
1435         ret
1436
1437 /*
1438  * There are two places in the kernel that can potentially fault with
1439  * usergs. Handle them here. The exception handlers after iret run with
1440  * kernel gs again, so don't set the user space flag. B stepping K8s
1441  * sometimes report an truncated RIP for IRET exceptions returning to
1442  * compat mode. Check for these here too.
1443  */
1444 error_kernelspace:
1445         incl %ebx
1446         leaq irq_return(%rip),%rcx
1447         cmpq %rcx,RIP+8(%rsp)
1448         je error_swapgs
1449         movl %ecx,%eax  /* zero extend */
1450         cmpq %rax,RIP+8(%rsp)
1451         je bstep_iret
1452         cmpq $gs_change,RIP+8(%rsp)
1453         je error_swapgs
1454         jmp error_sti
1455
1456 bstep_iret:
1457         /* Fix truncated RIP */
1458         movq %rcx,RIP+8(%rsp)
1459         jmp error_swapgs
1460         CFI_ENDPROC
1461 END(error_entry)
1462
1463
1464 /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
1465 ENTRY(error_exit)
1466         DEFAULT_FRAME
1467         movl %ebx,%eax
1468         RESTORE_REST
1469         DISABLE_INTERRUPTS(CLBR_NONE)
1470         TRACE_IRQS_OFF
1471         GET_THREAD_INFO(%rcx)
1472         testl %eax,%eax
1473         jne retint_kernel
1474         LOCKDEP_SYS_EXIT_IRQ
1475         movl TI_flags(%rcx),%edx
1476         movl $_TIF_WORK_MASK,%edi
1477         andl %edi,%edx
1478         jnz retint_careful
1479         jmp retint_swapgs
1480         CFI_ENDPROC
1481 END(error_exit)
1482
1483
1484         /* runs on exception stack */
1485 ENTRY(nmi)
1486         INTR_FRAME
1487         PARAVIRT_ADJUST_EXCEPTION_FRAME
1488         pushq_cfi $-1
1489         subq $ORIG_RAX-R15, %rsp
1490         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1491         call save_paranoid
1492         DEFAULT_FRAME 0
1493         /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
1494         movq %rsp,%rdi
1495         movq $-1,%rsi
1496         call do_nmi
1497 #ifdef CONFIG_TRACE_IRQFLAGS
1498         /* paranoidexit; without TRACE_IRQS_OFF */
1499         /* ebx: no swapgs flag */
1500         DISABLE_INTERRUPTS(CLBR_NONE)
1501         testl %ebx,%ebx                         /* swapgs needed? */
1502         jnz nmi_restore
1503         testl $3,CS(%rsp)
1504         jnz nmi_userspace
1505 nmi_swapgs:
1506         SWAPGS_UNSAFE_STACK
1507 nmi_restore:
1508         RESTORE_ALL 8
1509         jmp irq_return
1510 nmi_userspace:
1511         GET_THREAD_INFO(%rcx)
1512         movl TI_flags(%rcx),%ebx
1513         andl $_TIF_WORK_MASK,%ebx
1514         jz nmi_swapgs
1515         movq %rsp,%rdi                  /* &pt_regs */
1516         call sync_regs
1517         movq %rax,%rsp                  /* switch stack for scheduling */
1518         testl $_TIF_NEED_RESCHED,%ebx
1519         jnz nmi_schedule
1520         movl %ebx,%edx                  /* arg3: thread flags */
1521         ENABLE_INTERRUPTS(CLBR_NONE)
1522         xorl %esi,%esi                  /* arg2: oldset */
1523         movq %rsp,%rdi                  /* arg1: &pt_regs */
1524         call do_notify_resume
1525         DISABLE_INTERRUPTS(CLBR_NONE)
1526         jmp nmi_userspace
1527 nmi_schedule:
1528         ENABLE_INTERRUPTS(CLBR_ANY)
1529         call schedule
1530         DISABLE_INTERRUPTS(CLBR_ANY)
1531         jmp nmi_userspace
1532         CFI_ENDPROC
1533 #else
1534         jmp paranoid_exit
1535         CFI_ENDPROC
1536 #endif
1537 END(nmi)
1538
1539 ENTRY(ignore_sysret)
1540         CFI_STARTPROC
1541         mov $-ENOSYS,%eax
1542         sysret
1543         CFI_ENDPROC
1544 END(ignore_sysret)
1545
1546 /*
1547  * End of kprobes section
1548  */
1549         .popsection