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_types.h>
  52 #include <asm/irqflags.h>
  53 #include <asm/paravirt.h>
  54 #include <asm/ftrace.h>
  55 #include <asm/percpu.h>
  56
  57 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
  58 #include <linux/elf-em.h>
  59 #define AUDIT_ARCH_X86_64       (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
  60 #define __AUDIT_ARCH_64BIT 0x80000000
  61 #define __AUDIT_ARCH_LE    0x40000000
  62
  63         .code64
  64         .section .entry.text, "ax"
  65
  66 #ifdef CONFIG_FUNCTION_TRACER
  67 #ifdef CONFIG_DYNAMIC_FTRACE
  68 ENTRY(mcount)
  69         retq
  70 END(mcount)
  71
  72 ENTRY(ftrace_caller)
  73         cmpl $0, function_trace_stop
  74         jne  ftrace_stub
  75
  76         MCOUNT_SAVE_FRAME
  77
  78         movq 0x38(%rsp), %rdi
  79         movq 8(%rbp), %rsi
  80         subq $MCOUNT_INSN_SIZE, %rdi
  81
  82 GLOBAL(ftrace_call)
  83         call ftrace_stub
  84
  85         MCOUNT_RESTORE_FRAME
  86
  87 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  88 GLOBAL(ftrace_graph_call)
  89         jmp ftrace_stub
  90 #endif
  91
  92 GLOBAL(ftrace_stub)
  93         retq
  94 END(ftrace_caller)
  95
  96 #else /* ! CONFIG_DYNAMIC_FTRACE */
  97 ENTRY(mcount)
  98         cmpl $0, function_trace_stop
  99         jne  ftrace_stub
 100
 101         cmpq $ftrace_stub, ftrace_trace_function
 102         jnz trace
 103
 104 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 105         cmpq $ftrace_stub, ftrace_graph_return
 106         jnz ftrace_graph_caller
 107
 108         cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
 109         jnz ftrace_graph_caller
 110 #endif
 111
 112 GLOBAL(ftrace_stub)
 113         retq
 114
 115 trace:
 116         MCOUNT_SAVE_FRAME
 117
 118         movq 0x38(%rsp), %rdi
 119         movq 8(%rbp), %rsi
 120         subq $MCOUNT_INSN_SIZE, %rdi
 121
 122         call   *ftrace_trace_function
 123
 124         MCOUNT_RESTORE_FRAME
 125
 126         jmp ftrace_stub
 127 END(mcount)
 128 #endif /* CONFIG_DYNAMIC_FTRACE */
 129 #endif /* CONFIG_FUNCTION_TRACER */
 130
 131 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 132 ENTRY(ftrace_graph_caller)
 133         cmpl $0, function_trace_stop
 134         jne ftrace_stub
 135
 136         MCOUNT_SAVE_FRAME
 137
 138         leaq 8(%rbp), %rdi
 139         movq 0x38(%rsp), %rsi
 140         movq (%rbp), %rdx
 141         subq $MCOUNT_INSN_SIZE, %rsi
 142
 143         call    prepare_ftrace_return
 144
 145         MCOUNT_RESTORE_FRAME
 146
 147         retq
 148 END(ftrace_graph_caller)
 149
 150 GLOBAL(return_to_handler)
 151         subq  $24, %rsp
 152
 153         /* Save the return values */
 154         movq %rax, (%rsp)
 155         movq %rdx, 8(%rsp)
 156         movq %rbp, %rdi
 157
 158         call ftrace_return_to_handler
 159
 160         movq %rax, %rdi
 161         movq 8(%rsp), %rdx
 162         movq (%rsp), %rax
 163         addq $24, %rsp
 164         jmp *%rdi
 165 #endif
 166
 167
 168 #ifndef CONFIG_PREEMPT
 169 #define retint_kernel retint_restore_args
 170 #endif
 171
 172 #ifdef CONFIG_PARAVIRT
 173 ENTRY(native_usergs_sysret64)
 174         swapgs
 175         sysretq
 176 ENDPROC(native_usergs_sysret64)
 177 #endif /* CONFIG_PARAVIRT */
 178
 179
 180 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
 181 #ifdef CONFIG_TRACE_IRQFLAGS
 182         bt   $9,EFLAGS-\offset(%rsp)    /* interrupts off? */
 183         jnc  1f
 184         TRACE_IRQS_ON
 185 1:
 186 #endif
 187 .endm
 188
 189 /*
 190  * C code is not supposed to know about undefined top of stack. Every time
 191  * a C function with an pt_regs argument is called from the SYSCALL based
 192  * fast path FIXUP_TOP_OF_STACK is needed.
 193  * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
 194  * manipulation.
 195  */
 196
 197         /* %rsp:at FRAMEEND */
 198         .macro FIXUP_TOP_OF_STACK tmp offset=0
 199         movq PER_CPU_VAR(old_rsp),\tmp
 200         movq \tmp,RSP+\offset(%rsp)
 201         movq $__USER_DS,SS+\offset(%rsp)
 202         movq $__USER_CS,CS+\offset(%rsp)
 203         movq $-1,RCX+\offset(%rsp)
 204         movq R11+\offset(%rsp),\tmp  /* get eflags */
 205         movq \tmp,EFLAGS+\offset(%rsp)
 206         .endm
 207
 208         .macro RESTORE_TOP_OF_STACK tmp offset=0
 209         movq RSP+\offset(%rsp),\tmp
 210         movq \tmp,PER_CPU_VAR(old_rsp)
 211         movq EFLAGS+\offset(%rsp),\tmp
 212         movq \tmp,R11+\offset(%rsp)
 213         .endm
 214
 215         .macro FAKE_STACK_FRAME child_rip
 216         /* push in order ss, rsp, eflags, cs, rip */
 217         xorl %eax, %eax
 218         pushq_cfi $__KERNEL_DS /* ss */
 219         /*CFI_REL_OFFSET        ss,0*/
 220         pushq_cfi %rax /* rsp */
 221         CFI_REL_OFFSET  rsp,0
 222         pushq_cfi $X86_EFLAGS_IF /* eflags - interrupts on */
 223         /*CFI_REL_OFFSET        rflags,0*/
 224         pushq_cfi $__KERNEL_CS /* cs */
 225         /*CFI_REL_OFFSET        cs,0*/
 226         pushq_cfi \child_rip /* rip */
 227         CFI_REL_OFFSET  rip,0
 228         pushq_cfi %rax /* orig rax */
 229         .endm
 230
 231         .macro UNFAKE_STACK_FRAME
 232         addq $8*6, %rsp
 233         CFI_ADJUST_CFA_OFFSET   -(6*8)
 234         .endm
 235
 236 /*
 237  * initial frame state for interrupts (and exceptions without error code)
 238  */
 239         .macro EMPTY_FRAME start=1 offset=0
 240         .if \start
 241         CFI_STARTPROC simple
 242         CFI_SIGNAL_FRAME
 243         CFI_DEF_CFA rsp,8+\offset
 244         .else
 245         CFI_DEF_CFA_OFFSET 8+\offset
 246         .endif
 247         .endm
 248
 249 /*
 250  * initial frame state for interrupts (and exceptions without error code)
 251  */
 252         .macro INTR_FRAME start=1 offset=0
 253         EMPTY_FRAME \start, SS+8+\offset-RIP
 254         /*CFI_REL_OFFSET ss, SS+\offset-RIP*/
 255         CFI_REL_OFFSET rsp, RSP+\offset-RIP
 256         /*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/
 257         /*CFI_REL_OFFSET cs, CS+\offset-RIP*/
 258         CFI_REL_OFFSET rip, RIP+\offset-RIP
 259         .endm
 260
 261 /*
 262  * initial frame state for exceptions with error code (and interrupts
 263  * with vector already pushed)
 264  */
 265         .macro XCPT_FRAME start=1 offset=0
 266         INTR_FRAME \start, RIP+\offset-ORIG_RAX
 267         /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
 268         .endm
 269
 270 /*
 271  * frame that enables calling into C.
 272  */
 273         .macro PARTIAL_FRAME start=1 offset=0
 274         XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET
 275         CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET
 276         CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET
 277         CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET
 278         CFI_REL_OFFSET rcx, RCX+\offset-ARGOFFSET
 279         CFI_REL_OFFSET rax, RAX+\offset-ARGOFFSET
 280         CFI_REL_OFFSET r8, R8+\offset-ARGOFFSET
 281         CFI_REL_OFFSET r9, R9+\offset-ARGOFFSET
 282         CFI_REL_OFFSET r10, R10+\offset-ARGOFFSET
 283         CFI_REL_OFFSET r11, R11+\offset-ARGOFFSET
 284         .endm
 285
 286 /*
 287  * frame that enables passing a complete pt_regs to a C function.
 288  */
 289         .macro DEFAULT_FRAME start=1 offset=0
 290         PARTIAL_FRAME \start, R11+\offset-R15
 291         CFI_REL_OFFSET rbx, RBX+\offset
 292         CFI_REL_OFFSET rbp, RBP+\offset
 293         CFI_REL_OFFSET r12, R12+\offset
 294         CFI_REL_OFFSET r13, R13+\offset
 295         CFI_REL_OFFSET r14, R14+\offset
 296         CFI_REL_OFFSET r15, R15+\offset
 297         .endm
 298
 299 /* save partial stack frame */
 300         .pushsection .kprobes.text, "ax"
 301 ENTRY(save_args)
 302         XCPT_FRAME
 303         cld
 304         /*
 305          * start from rbp in pt_regs and jump over
 306          * return address.
 307          */
 308         movq_cfi rdi, RDI+8-RBP
 309         movq_cfi rsi, RSI+8-RBP
 310         movq_cfi rdx, RDX+8-RBP
 311         movq_cfi rcx, RCX+8-RBP
 312         movq_cfi rax, RAX+8-RBP
 313         movq_cfi  r8,  R8+8-RBP
 314         movq_cfi  r9,  R9+8-RBP
 315         movq_cfi r10, R10+8-RBP
 316         movq_cfi r11, R11+8-RBP
 317
 318         leaq -RBP+8(%rsp),%rdi  /* arg1 for handler */
 319         movq_cfi rbp, 8         /* push %rbp */
 320         leaq 8(%rsp), %rbp              /* mov %rsp, %ebp */
 321         testl $3, CS(%rdi)
 322         je 1f
 323         SWAPGS
 324         /*
 325          * irq_count is used to check if a CPU is already on an interrupt stack
 326          * or not. While this is essentially redundant with preempt_count it is
 327          * a little cheaper to use a separate counter in the PDA (short of
 328          * moving irq_enter into assembly, which would be too much work)
 329          */
 330 1:      incl PER_CPU_VAR(irq_count)
 331         jne 2f
 332         popq_cfi %rax                   /* move return address... */
 333         mov PER_CPU_VAR(irq_stack_ptr),%rsp
 334         EMPTY_FRAME 0
 335         pushq_cfi %rbp                  /* backlink for unwinder */
 336         pushq_cfi %rax                  /* ... to the new stack */
 337         /*
 338          * We entered an interrupt context - irqs are off:
 339          */
 340 2:      TRACE_IRQS_OFF
 341         ret
 342         CFI_ENDPROC
 343 END(save_args)
 344         .popsection
 345
 346 ENTRY(save_rest)
 347         PARTIAL_FRAME 1 REST_SKIP+8
 348         movq 5*8+16(%rsp), %r11 /* save return address */
 349         movq_cfi rbx, RBX+16
 350         movq_cfi rbp, RBP+16
 351         movq_cfi r12, R12+16
 352         movq_cfi r13, R13+16
 353         movq_cfi r14, R14+16
 354         movq_cfi r15, R15+16
 355         movq %r11, 8(%rsp)      /* return address */
 356         FIXUP_TOP_OF_STACK %r11, 16
 357         ret
 358         CFI_ENDPROC
 359 END(save_rest)
 360
 361 /* save complete stack frame */
 362         .pushsection .kprobes.text, "ax"
 363 ENTRY(save_paranoid)
 364         XCPT_FRAME 1 RDI+8
 365         cld
 366         movq_cfi rdi, RDI+8
 367         movq_cfi rsi, RSI+8
 368         movq_cfi rdx, RDX+8
 369         movq_cfi rcx, RCX+8
 370         movq_cfi rax, RAX+8
 371         movq_cfi r8, R8+8
 372         movq_cfi r9, R9+8
 373         movq_cfi r10, R10+8
 374         movq_cfi r11, R11+8
 375         movq_cfi rbx, RBX+8
 376         movq_cfi rbp, RBP+8
 377         movq_cfi r12, R12+8
 378         movq_cfi r13, R13+8
 379         movq_cfi r14, R14+8
 380         movq_cfi r15, R15+8
 381         movl $1,%ebx
 382         movl $MSR_GS_BASE,%ecx
 383         rdmsr
 384         testl %edx,%edx
 385         js 1f   /* negative -> in kernel */
 386         SWAPGS
 387         xorl %ebx,%ebx
 388 1:      ret
 389         CFI_ENDPROC
 390 END(save_paranoid)
 391         .popsection
 392
 393 /*
 394  * A newly forked process directly context switches into this address.
 395  *
 396  * rdi: prev task we switched from
 397  */
 398 ENTRY(ret_from_fork)
 399         DEFAULT_FRAME
 400
 401         LOCK ; btr $TIF_FORK,TI_flags(%r8)
 402
 403         pushq_cfi kernel_eflags(%rip)
 404         popfq_cfi                               # reset kernel eflags
 405
 406         call schedule_tail                      # rdi: 'prev' task parameter
 407
 408         GET_THREAD_INFO(%rcx)
 409
 410         RESTORE_REST
 411
 412         testl $3, CS-ARGOFFSET(%rsp)            # from kernel_thread?
 413         je   int_ret_from_sys_call
 414
 415         testl $_TIF_IA32, TI_flags(%rcx)        # 32-bit compat task needs IRET
 416         jnz  int_ret_from_sys_call
 417
 418         RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
 419         jmp ret_from_sys_call                   # go to the SYSRET fastpath
 420
 421         CFI_ENDPROC
 422 END(ret_from_fork)
 423
 424 /*
 425  * System call entry. Upto 6 arguments in registers are supported.
 426  *
 427  * SYSCALL does not save anything on the stack and does not change the
 428  * stack pointer.
 429  */
 430
 431 /*
 432  * Register setup:
 433  * rax  system call number
 434  * rdi  arg0
 435  * rcx  return address for syscall/sysret, C arg3
 436  * rsi  arg1
 437  * rdx  arg2
 438  * r10  arg3    (--> moved to rcx for C)
 439  * r8   arg4
 440  * r9   arg5
 441  * r11  eflags for syscall/sysret, temporary for C
 442  * r12-r15,rbp,rbx saved by C code, not touched.
 443  *
 444  * Interrupts are off on entry.
 445  * Only called from user space.
 446  *
 447  * XXX  if we had a free scratch register we could save the RSP into the stack frame
 448  *      and report it properly in ps. Unfortunately we haven't.
 449  *
 450  * When user can change the frames always force IRET. That is because
 451  * it deals with uncanonical addresses better. SYSRET has trouble
 452  * with them due to bugs in both AMD and Intel CPUs.
 453  */
 454
 455 ENTRY(system_call)
 456         CFI_STARTPROC   simple
 457         CFI_SIGNAL_FRAME
 458         CFI_DEF_CFA     rsp,KERNEL_STACK_OFFSET
 459         CFI_REGISTER    rip,rcx
 460         /*CFI_REGISTER  rflags,r11*/
 461         SWAPGS_UNSAFE_STACK
 462         /*
 463          * A hypervisor implementation might want to use a label
 464          * after the swapgs, so that it can do the swapgs
 465          * for the guest and jump here on syscall.
 466          */
 467 ENTRY(system_call_after_swapgs)
 468
 469         movq    %rsp,PER_CPU_VAR(old_rsp)
 470         movq    PER_CPU_VAR(kernel_stack),%rsp
 471         /*
 472          * No need to follow this irqs off/on section - it's straight
 473          * and short:
 474          */
 475         ENABLE_INTERRUPTS(CLBR_NONE)
 476         SAVE_ARGS 8,1
 477         movq  %rax,ORIG_RAX-ARGOFFSET(%rsp)
 478         movq  %rcx,RIP-ARGOFFSET(%rsp)
 479         CFI_REL_OFFSET rip,RIP-ARGOFFSET
 480         GET_THREAD_INFO(%rcx)
 481         testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%rcx)
 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         GET_THREAD_INFO(%rcx)
 499         DISABLE_INTERRUPTS(CLBR_NONE)
 500         TRACE_IRQS_OFF
 501         movl TI_flags(%rcx),%edx
 502         andl %edi,%edx
 503         jnz  sysret_careful
 504         CFI_REMEMBER_STATE
 505         /*
 506          * sysretq will re-enable interrupts:
 507          */
 508         TRACE_IRQS_ON
 509         movq RIP-ARGOFFSET(%rsp),%rcx
 510         CFI_REGISTER    rip,rcx
 511         RESTORE_ARGS 0,-ARG_SKIP,1
 512         /*CFI_REGISTER  rflags,r11*/
 513         movq    PER_CPU_VAR(old_rsp), %rsp
 514         USERGS_SYSRET64
 515
 516         CFI_RESTORE_STATE
 517         /* Handle reschedules */
 518         /* edx: work, edi: workmask */
 519 sysret_careful:
 520         bt $TIF_NEED_RESCHED,%edx
 521         jnc sysret_signal
 522         TRACE_IRQS_ON
 523         ENABLE_INTERRUPTS(CLBR_NONE)
 524         pushq_cfi %rdi
 525         call schedule
 526         popq_cfi %rdi
 527         jmp sysret_check
 528
 529         /* Handle a signal */
 530 sysret_signal:
 531         TRACE_IRQS_ON
 532         ENABLE_INTERRUPTS(CLBR_NONE)
 533 #ifdef CONFIG_AUDITSYSCALL
 534         bt $TIF_SYSCALL_AUDIT,%edx
 535         jc sysret_audit
 536 #endif
 537         /*
 538          * We have a signal, or exit tracing or single-step.
 539          * These all wind up with the iret return path anyway,
 540          * so just join that path right now.
 541          */
 542         FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
 543         jmp int_check_syscall_exit_work
 544
 545 badsys:
 546         movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
 547         jmp ret_from_sys_call
 548
 549 #ifdef CONFIG_AUDITSYSCALL
 550         /*
 551          * Fast path for syscall audit without full syscall trace.
 552          * We just call audit_syscall_entry() directly, and then
 553          * jump back to the normal fast path.
 554          */
 555 auditsys:
 556         movq %r10,%r9                   /* 6th arg: 4th syscall arg */
 557         movq %rdx,%r8                   /* 5th arg: 3rd syscall arg */
 558         movq %rsi,%rcx                  /* 4th arg: 2nd syscall arg */
 559         movq %rdi,%rdx                  /* 3rd arg: 1st syscall arg */
 560         movq %rax,%rsi                  /* 2nd arg: syscall number */
 561         movl $AUDIT_ARCH_X86_64,%edi    /* 1st arg: audit arch */
 562         call audit_syscall_entry
 563         LOAD_ARGS 0             /* reload call-clobbered registers */
 564         jmp system_call_fastpath
 565
 566         /*
 567          * Return fast path for syscall audit.  Call audit_syscall_exit()
 568          * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
 569          * masked off.
 570          */
 571 sysret_audit:
 572         movq RAX-ARGOFFSET(%rsp),%rsi   /* second arg, syscall return value */
 573         cmpq $0,%rsi            /* is it < 0? */
 574         setl %al                /* 1 if so, 0 if not */
 575         movzbl %al,%edi         /* zero-extend that into %edi */
 576         inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
 577         call audit_syscall_exit
 578         movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
 579         jmp sysret_check
 580 #endif  /* CONFIG_AUDITSYSCALL */
 581
 582         /* Do syscall tracing */
 583 tracesys:
 584 #ifdef CONFIG_AUDITSYSCALL
 585         testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
 586         jz auditsys
 587 #endif
 588         SAVE_REST
 589         movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
 590         FIXUP_TOP_OF_STACK %rdi
 591         movq %rsp,%rdi
 592         call syscall_trace_enter
 593         /*
 594          * Reload arg registers from stack in case ptrace changed them.
 595          * We don't reload %rax because syscall_trace_enter() returned
 596          * the value it wants us to use in the table lookup.
 597          */
 598         LOAD_ARGS ARGOFFSET, 1
 599         RESTORE_REST
 600         cmpq $__NR_syscall_max,%rax
 601         ja   int_ret_from_sys_call      /* RAX(%rsp) set to -ENOSYS above */
 602         movq %r10,%rcx  /* fixup for C */
 603         call *sys_call_table(,%rax,8)
 604         movq %rax,RAX-ARGOFFSET(%rsp)
 605         /* Use IRET because user could have changed frame */
 606
 607 /*
 608  * Syscall return path ending with IRET.
 609  * Has correct top of stack, but partial stack frame.
 610  */
 611 GLOBAL(int_ret_from_sys_call)
 612         DISABLE_INTERRUPTS(CLBR_NONE)
 613         TRACE_IRQS_OFF
 614         testl $3,CS-ARGOFFSET(%rsp)
 615         je retint_restore_args
 616         movl $_TIF_ALLWORK_MASK,%edi
 617         /* edi: mask to check */
 618 GLOBAL(int_with_check)
 619         LOCKDEP_SYS_EXIT_IRQ
 620         GET_THREAD_INFO(%rcx)
 621         movl TI_flags(%rcx),%edx
 622         andl %edi,%edx
 623         jnz   int_careful
 624         andl    $~TS_COMPAT,TI_status(%rcx)
 625         jmp   retint_swapgs
 626
 627         /* Either reschedule or signal or syscall exit tracking needed. */
 628         /* First do a reschedule test. */
 629         /* edx: work, edi: workmask */
 630 int_careful:
 631         bt $TIF_NEED_RESCHED,%edx
 632         jnc  int_very_careful
 633         TRACE_IRQS_ON
 634         ENABLE_INTERRUPTS(CLBR_NONE)
 635         pushq_cfi %rdi
 636         call schedule
 637         popq_cfi %rdi
 638         DISABLE_INTERRUPTS(CLBR_NONE)
 639         TRACE_IRQS_OFF
 640         jmp int_with_check
 641
 642         /* handle signals and tracing -- both require a full stack frame */
 643 int_very_careful:
 644         TRACE_IRQS_ON
 645         ENABLE_INTERRUPTS(CLBR_NONE)
 646 int_check_syscall_exit_work:
 647         SAVE_REST
 648         /* Check for syscall exit trace */
 649         testl $_TIF_WORK_SYSCALL_EXIT,%edx
 650         jz int_signal
 651         pushq_cfi %rdi
 652         leaq 8(%rsp),%rdi       # &ptregs -> arg1
 653         call syscall_trace_leave
 654         popq_cfi %rdi
 655         andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
 656         jmp int_restore_rest
 657
 658 int_signal:
 659         testl $_TIF_DO_NOTIFY_MASK,%edx
 660         jz 1f
 661         movq %rsp,%rdi          # &ptregs -> arg1
 662         xorl %esi,%esi          # oldset -> arg2
 663         call do_notify_resume
 664 1:      movl $_TIF_WORK_MASK,%edi
 665 int_restore_rest:
 666         RESTORE_REST
 667         DISABLE_INTERRUPTS(CLBR_NONE)
 668         TRACE_IRQS_OFF
 669         jmp int_with_check
 670         CFI_ENDPROC
 671 END(system_call)
 672
 673 /*
 674  * Certain special system calls that need to save a complete full stack frame.
 675  */
 676         .macro PTREGSCALL label,func,arg
 677 ENTRY(\label)
 678         PARTIAL_FRAME 1 8               /* offset 8: return address */
 679         subq $REST_SKIP, %rsp
 680         CFI_ADJUST_CFA_OFFSET REST_SKIP
 681         call save_rest
 682         DEFAULT_FRAME 0 8               /* offset 8: return address */
 683         leaq 8(%rsp), \arg      /* pt_regs pointer */
 684         call \func
 685         jmp ptregscall_common
 686         CFI_ENDPROC
 687 END(\label)
 688         .endm
 689
 690         PTREGSCALL stub_clone, sys_clone, %r8
 691         PTREGSCALL stub_fork, sys_fork, %rdi
 692         PTREGSCALL stub_vfork, sys_vfork, %rdi
 693         PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
 694         PTREGSCALL stub_iopl, sys_iopl, %rsi
 695
 696 ENTRY(ptregscall_common)
 697         DEFAULT_FRAME 1 8       /* offset 8: return address */
 698         RESTORE_TOP_OF_STACK %r11, 8
 699         movq_cfi_restore R15+8, r15
 700         movq_cfi_restore R14+8, r14
 701         movq_cfi_restore R13+8, r13
 702         movq_cfi_restore R12+8, r12
 703         movq_cfi_restore RBP+8, rbp
 704         movq_cfi_restore RBX+8, rbx
 705         ret $REST_SKIP          /* pop extended registers */
 706         CFI_ENDPROC
 707 END(ptregscall_common)
 708
 709 ENTRY(stub_execve)
 710         CFI_STARTPROC
 711         addq $8, %rsp
 712         PARTIAL_FRAME 0
 713         SAVE_REST
 714         FIXUP_TOP_OF_STACK %r11
 715         movq %rsp, %rcx
 716         call sys_execve
 717         RESTORE_TOP_OF_STACK %r11
 718         movq %rax,RAX(%rsp)
 719         RESTORE_REST
 720         jmp int_ret_from_sys_call
 721         CFI_ENDPROC
 722 END(stub_execve)
 723
 724 /*
 725  * sigreturn is special because it needs to restore all registers on return.
 726  * This cannot be done with SYSRET, so use the IRET return path instead.
 727  */
 728 ENTRY(stub_rt_sigreturn)
 729         CFI_STARTPROC
 730         addq $8, %rsp
 731         PARTIAL_FRAME 0
 732         SAVE_REST
 733         movq %rsp,%rdi
 734         FIXUP_TOP_OF_STACK %r11
 735         call sys_rt_sigreturn
 736         movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
 737         RESTORE_REST
 738         jmp int_ret_from_sys_call
 739         CFI_ENDPROC
 740 END(stub_rt_sigreturn)
 741
 742 /*
 743  * Build the entry stubs and pointer table with some assembler magic.
 744  * We pack 7 stubs into a single 32-byte chunk, which will fit in a
 745  * single cache line on all modern x86 implementations.
 746  */
 747         .section .init.rodata,"a"
 748 ENTRY(interrupt)
 749         .section .entry.text
 750         .p2align 5
 751         .p2align CONFIG_X86_L1_CACHE_SHIFT
 752 ENTRY(irq_entries_start)
 753         INTR_FRAME
 754 vector=FIRST_EXTERNAL_VECTOR
 755 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
 756         .balign 32
 757   .rept 7
 758     .if vector < NR_VECTORS
 759       .if vector <> FIRST_EXTERNAL_VECTOR
 760         CFI_ADJUST_CFA_OFFSET -8
 761       .endif
 762 1:      pushq_cfi $(~vector+0x80)       /* Note: always in signed byte range */
 763       .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
 764         jmp 2f
 765       .endif
 766       .previous
 767         .quad 1b
 768       .section .entry.text
 769 vector=vector+1
 770     .endif
 771   .endr
 772 2:      jmp common_interrupt
 773 .endr
 774         CFI_ENDPROC
 775 END(irq_entries_start)
 776
 777 .previous
 778 END(interrupt)
 779 .previous
 780
 781 /*
 782  * Interrupt entry/exit.
 783  *
 784  * Interrupt entry points save only callee clobbered registers in fast path.
 785  *
 786  * Entry runs with interrupts off.
 787  */
 788
 789 /* 0(%rsp): ~(interrupt number) */
 790         .macro interrupt func
 791         /* reserve pt_regs for scratch regs and rbp */
 792         subq $ORIG_RAX-RBP, %rsp
 793         CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP
 794         call save_args
 795         PARTIAL_FRAME 0
 796         call \func
 797         .endm
 798
 799 /*
 800  * Interrupt entry/exit should be protected against kprobes
 801  */
 802         .pushsection .kprobes.text, "ax"
 803         /*
 804          * The interrupt stubs push (~vector+0x80) onto the stack and
 805          * then jump to common_interrupt.
 806          */
 807         .p2align CONFIG_X86_L1_CACHE_SHIFT
 808 common_interrupt:
 809         XCPT_FRAME
 810         addq $-0x80,(%rsp)              /* Adjust vector to [-256,-1] range */
 811         interrupt do_IRQ
 812         /* 0(%rsp): old_rsp-ARGOFFSET */
 813 ret_from_intr:
 814         DISABLE_INTERRUPTS(CLBR_NONE)
 815         TRACE_IRQS_OFF
 816         decl PER_CPU_VAR(irq_count)
 817         leaveq
 818
 819         CFI_RESTORE             rbp
 820         CFI_DEF_CFA_REGISTER    rsp
 821         CFI_ADJUST_CFA_OFFSET   -8
 822
 823         /* we did not save rbx, restore only from ARGOFFSET */
 824         addq $8, %rsp
 825         CFI_ADJUST_CFA_OFFSET   -8
 826 exit_intr:
 827         GET_THREAD_INFO(%rcx)
 828         testl $3,CS-ARGOFFSET(%rsp)
 829         je retint_kernel
 830
 831         /* Interrupt came from user space */
 832         /*
 833          * Has a correct top of stack, but a partial stack frame
 834          * %rcx: thread info. Interrupts off.
 835          */
 836 retint_with_reschedule:
 837         movl $_TIF_WORK_MASK,%edi
 838 retint_check:
 839         LOCKDEP_SYS_EXIT_IRQ
 840         movl TI_flags(%rcx),%edx
 841         andl %edi,%edx
 842         CFI_REMEMBER_STATE
 843         jnz  retint_careful
 844
 845 retint_swapgs:          /* return to user-space */
 846         /*
 847          * The iretq could re-enable interrupts:
 848          */
 849         DISABLE_INTERRUPTS(CLBR_ANY)
 850         TRACE_IRQS_IRETQ
 851         SWAPGS
 852         jmp restore_args
 853
 854 retint_restore_args:    /* return to kernel space */
 855         DISABLE_INTERRUPTS(CLBR_ANY)
 856         /*
 857          * The iretq could re-enable interrupts:
 858          */
 859         TRACE_IRQS_IRETQ
 860 restore_args:
 861         RESTORE_ARGS 0,8,0
 862
 863 irq_return:
 864         INTERRUPT_RETURN
 865
 866         .section __ex_table, "a"
 867         .quad irq_return, bad_iret
 868         .previous
 869
 870 #ifdef CONFIG_PARAVIRT
 871 ENTRY(native_iret)
 872         iretq
 873
 874         .section __ex_table,"a"
 875         .quad native_iret, bad_iret
 876         .previous
 877 #endif
 878
 879         .section .fixup,"ax"
 880 bad_iret:
 881         /*
 882          * The iret traps when the %cs or %ss being restored is bogus.
 883          * We've lost the original trap vector and error code.
 884          * #GPF is the most likely one to get for an invalid selector.
 885          * So pretend we completed the iret and took the #GPF in user mode.
 886          *
 887          * We are now running with the kernel GS after exception recovery.
 888          * But error_entry expects us to have user GS to match the user %cs,
 889          * so swap back.
 890          */
 891         pushq $0
 892
 893         SWAPGS
 894         jmp general_protection
 895
 896         .previous
 897
 898         /* edi: workmask, edx: work */
 899 retint_careful:
 900         CFI_RESTORE_STATE
 901         bt    $TIF_NEED_RESCHED,%edx
 902         jnc   retint_signal
 903         TRACE_IRQS_ON
 904         ENABLE_INTERRUPTS(CLBR_NONE)
 905         pushq_cfi %rdi
 906         call  schedule
 907         popq_cfi %rdi
 908         GET_THREAD_INFO(%rcx)
 909         DISABLE_INTERRUPTS(CLBR_NONE)
 910         TRACE_IRQS_OFF
 911         jmp retint_check
 912
 913 retint_signal:
 914         testl $_TIF_DO_NOTIFY_MASK,%edx
 915         jz    retint_swapgs
 916         TRACE_IRQS_ON
 917         ENABLE_INTERRUPTS(CLBR_NONE)
 918         SAVE_REST
 919         movq $-1,ORIG_RAX(%rsp)
 920         xorl %esi,%esi          # oldset
 921         movq %rsp,%rdi          # &pt_regs
 922         call do_notify_resume
 923         RESTORE_REST
 924         DISABLE_INTERRUPTS(CLBR_NONE)
 925         TRACE_IRQS_OFF
 926         GET_THREAD_INFO(%rcx)
 927         jmp retint_with_reschedule
 928
 929 #ifdef CONFIG_PREEMPT
 930         /* Returning to kernel space. Check if we need preemption */
 931         /* rcx:  threadinfo. interrupts off. */
 932 ENTRY(retint_kernel)
 933         cmpl $0,TI_preempt_count(%rcx)
 934         jnz  retint_restore_args
 935         bt  $TIF_NEED_RESCHED,TI_flags(%rcx)
 936         jnc  retint_restore_args
 937         bt   $9,EFLAGS-ARGOFFSET(%rsp)  /* interrupts off? */
 938         jnc  retint_restore_args
 939         call preempt_schedule_irq
 940         jmp exit_intr
 941 #endif
 942
 943         CFI_ENDPROC
 944 END(common_interrupt)
 945 /*
 946  * End of kprobes section
 947  */
 948        .popsection
 949
 950 /*
 951  * APIC interrupts.
 952  */
 953 .macro apicinterrupt num sym do_sym
 954 ENTRY(\sym)
 955         INTR_FRAME
 956         pushq_cfi $~(\num)
 957         interrupt \do_sym
 958         jmp ret_from_intr
 959         CFI_ENDPROC
 960 END(\sym)
 961 .endm
 962
 963 #ifdef CONFIG_SMP
 964 apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \
 965         irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt
 966 apicinterrupt REBOOT_VECTOR \
 967         reboot_interrupt smp_reboot_interrupt
 968 #endif
 969
 970 #ifdef CONFIG_X86_UV
 971 apicinterrupt UV_BAU_MESSAGE \
 972         uv_bau_message_intr1 uv_bau_message_interrupt
 973 #endif
 974 apicinterrupt LOCAL_TIMER_VECTOR \
 975         apic_timer_interrupt smp_apic_timer_interrupt
 976 apicinterrupt X86_PLATFORM_IPI_VECTOR \
 977         x86_platform_ipi smp_x86_platform_ipi
 978
 979 #ifdef CONFIG_SMP
 980 .irp idx,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \
 981         16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
 982 .if NUM_INVALIDATE_TLB_VECTORS > \idx
 983 apicinterrupt (INVALIDATE_TLB_VECTOR_START)+\idx \
 984         invalidate_interrupt\idx smp_invalidate_interrupt
 985 .endif
 986 .endr
 987 #endif
 988
 989 apicinterrupt THRESHOLD_APIC_VECTOR \
 990         threshold_interrupt smp_threshold_interrupt
 991 apicinterrupt THERMAL_APIC_VECTOR \
 992         thermal_interrupt smp_thermal_interrupt
 993
 994 #ifdef CONFIG_X86_MCE
 995 apicinterrupt MCE_SELF_VECTOR \
 996         mce_self_interrupt smp_mce_self_interrupt
 997 #endif
 998
 999 #ifdef CONFIG_SMP
1000 apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \
1001         call_function_single_interrupt smp_call_function_single_interrupt
1002 apicinterrupt CALL_FUNCTION_VECTOR \
1003         call_function_interrupt smp_call_function_interrupt
1004 apicinterrupt RESCHEDULE_VECTOR \
1005         reschedule_interrupt smp_reschedule_interrupt
1006 #endif
1007
1008 apicinterrupt ERROR_APIC_VECTOR \
1009         error_interrupt smp_error_interrupt
1010 apicinterrupt SPURIOUS_APIC_VECTOR \
1011         spurious_interrupt smp_spurious_interrupt
1012
1013 #ifdef CONFIG_IRQ_WORK
1014 apicinterrupt IRQ_WORK_VECTOR \
1015         irq_work_interrupt smp_irq_work_interrupt
1016 #endif
1017
1018 /*
1019  * Exception entry points.
1020  */
1021 .macro zeroentry sym do_sym
1022 ENTRY(\sym)
1023         INTR_FRAME
1024         PARAVIRT_ADJUST_EXCEPTION_FRAME
1025         pushq_cfi $-1           /* ORIG_RAX: no syscall to restart */
1026         subq $ORIG_RAX-R15, %rsp
1027         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1028         call error_entry
1029         DEFAULT_FRAME 0
1030         movq %rsp,%rdi          /* pt_regs pointer */
1031         xorl %esi,%esi          /* no error code */
1032         call \do_sym
1033         jmp error_exit          /* %ebx: no swapgs flag */
1034         CFI_ENDPROC
1035 END(\sym)
1036 .endm
1037
1038 .macro paranoidzeroentry sym do_sym
1039 ENTRY(\sym)
1040         INTR_FRAME
1041         PARAVIRT_ADJUST_EXCEPTION_FRAME
1042         pushq_cfi $-1           /* ORIG_RAX: no syscall to restart */
1043         subq $ORIG_RAX-R15, %rsp
1044         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1045         call save_paranoid
1046         TRACE_IRQS_OFF
1047         movq %rsp,%rdi          /* pt_regs pointer */
1048         xorl %esi,%esi          /* no error code */
1049         call \do_sym
1050         jmp paranoid_exit       /* %ebx: no swapgs flag */
1051         CFI_ENDPROC
1052 END(\sym)
1053 .endm
1054
1055 #define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
1056 .macro paranoidzeroentry_ist sym do_sym ist
1057 ENTRY(\sym)
1058         INTR_FRAME
1059         PARAVIRT_ADJUST_EXCEPTION_FRAME
1060         pushq_cfi $-1           /* ORIG_RAX: no syscall to restart */
1061         subq $ORIG_RAX-R15, %rsp
1062         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1063         call save_paranoid
1064         TRACE_IRQS_OFF
1065         movq %rsp,%rdi          /* pt_regs pointer */
1066         xorl %esi,%esi          /* no error code */
1067         subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1068         call \do_sym
1069         addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1070         jmp paranoid_exit       /* %ebx: no swapgs flag */
1071         CFI_ENDPROC
1072 END(\sym)
1073 .endm
1074
1075 .macro errorentry sym do_sym
1076 ENTRY(\sym)
1077         XCPT_FRAME
1078         PARAVIRT_ADJUST_EXCEPTION_FRAME
1079         subq $ORIG_RAX-R15, %rsp
1080         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1081         call error_entry
1082         DEFAULT_FRAME 0
1083         movq %rsp,%rdi                  /* pt_regs pointer */
1084         movq ORIG_RAX(%rsp),%rsi        /* get error code */
1085         movq $-1,ORIG_RAX(%rsp)         /* no syscall to restart */
1086         call \do_sym
1087         jmp error_exit                  /* %ebx: no swapgs flag */
1088         CFI_ENDPROC
1089 END(\sym)
1090 .endm
1091
1092         /* error code is on the stack already */
1093 .macro paranoiderrorentry sym do_sym
1094 ENTRY(\sym)
1095         XCPT_FRAME
1096         PARAVIRT_ADJUST_EXCEPTION_FRAME
1097         subq $ORIG_RAX-R15, %rsp
1098         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1099         call save_paranoid
1100         DEFAULT_FRAME 0
1101         TRACE_IRQS_OFF
1102         movq %rsp,%rdi                  /* pt_regs pointer */
1103         movq ORIG_RAX(%rsp),%rsi        /* get error code */
1104         movq $-1,ORIG_RAX(%rsp)         /* no syscall to restart */
1105         call \do_sym
1106         jmp paranoid_exit               /* %ebx: no swapgs flag */
1107         CFI_ENDPROC
1108 END(\sym)
1109 .endm
1110
1111 zeroentry divide_error do_divide_error
1112 zeroentry overflow do_overflow
1113 zeroentry bounds do_bounds
1114 zeroentry invalid_op do_invalid_op
1115 zeroentry device_not_available do_device_not_available
1116 paranoiderrorentry double_fault do_double_fault
1117 zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun
1118 errorentry invalid_TSS do_invalid_TSS
1119 errorentry segment_not_present do_segment_not_present
1120 zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
1121 zeroentry coprocessor_error do_coprocessor_error
1122 errorentry alignment_check do_alignment_check
1123 zeroentry simd_coprocessor_error do_simd_coprocessor_error
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