2 * linux/arch/x86_64/entry.S
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>
10 * entry.S contains the system-call and fault low-level handling routines.
12 * NOTE: This code handles signal-recognition, which happens every time
13 * after an interrupt and after each system call.
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.
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.
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.
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>
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>
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
64 #ifdef CONFIG_FUNCTION_TRACER
65 #ifdef CONFIG_DYNAMIC_FTRACE
71 cmpl $0, function_trace_stop
78 subq $MCOUNT_INSN_SIZE, %rdi
85 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
86 GLOBAL(ftrace_graph_call)
94 #else /* ! CONFIG_DYNAMIC_FTRACE */
96 cmpl $0, function_trace_stop
99 cmpq $ftrace_stub, ftrace_trace_function
102 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
103 cmpq $ftrace_stub, ftrace_graph_return
104 jnz ftrace_graph_caller
106 cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
107 jnz ftrace_graph_caller
116 movq 0x38(%rsp), %rdi
118 subq $MCOUNT_INSN_SIZE, %rdi
120 call *ftrace_trace_function
126 #endif /* CONFIG_DYNAMIC_FTRACE */
127 #endif /* CONFIG_FUNCTION_TRACER */
129 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
130 ENTRY(ftrace_graph_caller)
131 cmpl $0, function_trace_stop
137 movq 0x38(%rsp), %rsi
139 subq $MCOUNT_INSN_SIZE, %rsi
141 call prepare_ftrace_return
146 END(ftrace_graph_caller)
148 GLOBAL(return_to_handler)
151 /* Save the return values */
156 call ftrace_return_to_handler
166 #ifndef CONFIG_PREEMPT
167 #define retint_kernel retint_restore_args
170 #ifdef CONFIG_PARAVIRT
171 ENTRY(native_usergs_sysret64)
174 ENDPROC(native_usergs_sysret64)
175 #endif /* CONFIG_PARAVIRT */
178 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
179 #ifdef CONFIG_TRACE_IRQFLAGS
180 bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */
188 * C code is not supposed to know about undefined top of stack. Every time
189 * a C function with an pt_regs argument is called from the SYSCALL based
190 * fast path FIXUP_TOP_OF_STACK is needed.
191 * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
195 /* %rsp:at FRAMEEND */
196 .macro FIXUP_TOP_OF_STACK tmp offset=0
197 movq PER_CPU_VAR(old_rsp),\tmp
198 movq \tmp,RSP+\offset(%rsp)
199 movq $__USER_DS,SS+\offset(%rsp)
200 movq $__USER_CS,CS+\offset(%rsp)
201 movq $-1,RCX+\offset(%rsp)
202 movq R11+\offset(%rsp),\tmp /* get eflags */
203 movq \tmp,EFLAGS+\offset(%rsp)
206 .macro RESTORE_TOP_OF_STACK tmp offset=0
207 movq RSP+\offset(%rsp),\tmp
208 movq \tmp,PER_CPU_VAR(old_rsp)
209 movq EFLAGS+\offset(%rsp),\tmp
210 movq \tmp,R11+\offset(%rsp)
213 .macro FAKE_STACK_FRAME child_rip
214 /* push in order ss, rsp, eflags, cs, rip */
216 pushq $__KERNEL_DS /* ss */
217 CFI_ADJUST_CFA_OFFSET 8
218 /*CFI_REL_OFFSET ss,0*/
220 CFI_ADJUST_CFA_OFFSET 8
222 pushq $X86_EFLAGS_IF /* eflags - interrupts on */
223 CFI_ADJUST_CFA_OFFSET 8
224 /*CFI_REL_OFFSET rflags,0*/
225 pushq $__KERNEL_CS /* cs */
226 CFI_ADJUST_CFA_OFFSET 8
227 /*CFI_REL_OFFSET cs,0*/
228 pushq \child_rip /* rip */
229 CFI_ADJUST_CFA_OFFSET 8
231 pushq %rax /* orig rax */
232 CFI_ADJUST_CFA_OFFSET 8
235 .macro UNFAKE_STACK_FRAME
237 CFI_ADJUST_CFA_OFFSET -(6*8)
241 * initial frame state for interrupts (and exceptions without error code)
243 .macro EMPTY_FRAME start=1 offset=0
247 CFI_DEF_CFA rsp,8+\offset
249 CFI_DEF_CFA_OFFSET 8+\offset
254 * initial frame state for interrupts (and exceptions without error code)
256 .macro INTR_FRAME start=1 offset=0
257 EMPTY_FRAME \start, SS+8+\offset-RIP
258 /*CFI_REL_OFFSET ss, SS+\offset-RIP*/
259 CFI_REL_OFFSET rsp, RSP+\offset-RIP
260 /*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/
261 /*CFI_REL_OFFSET cs, CS+\offset-RIP*/
262 CFI_REL_OFFSET rip, RIP+\offset-RIP
266 * initial frame state for exceptions with error code (and interrupts
267 * with vector already pushed)
269 .macro XCPT_FRAME start=1 offset=0
270 INTR_FRAME \start, RIP+\offset-ORIG_RAX
271 /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
275 * frame that enables calling into C.
277 .macro PARTIAL_FRAME start=1 offset=0
278 XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET
279 CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET
280 CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET
281 CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET
282 CFI_REL_OFFSET rcx, RCX+\offset-ARGOFFSET
283 CFI_REL_OFFSET rax, RAX+\offset-ARGOFFSET
284 CFI_REL_OFFSET r8, R8+\offset-ARGOFFSET
285 CFI_REL_OFFSET r9, R9+\offset-ARGOFFSET
286 CFI_REL_OFFSET r10, R10+\offset-ARGOFFSET
287 CFI_REL_OFFSET r11, R11+\offset-ARGOFFSET
291 * frame that enables passing a complete pt_regs to a C function.
293 .macro DEFAULT_FRAME start=1 offset=0
294 PARTIAL_FRAME \start, R11+\offset-R15
295 CFI_REL_OFFSET rbx, RBX+\offset
296 CFI_REL_OFFSET rbp, RBP+\offset
297 CFI_REL_OFFSET r12, R12+\offset
298 CFI_REL_OFFSET r13, R13+\offset
299 CFI_REL_OFFSET r14, R14+\offset
300 CFI_REL_OFFSET r15, R15+\offset
303 /* save partial stack frame */
307 movq_cfi rdi, RDI+16-ARGOFFSET
308 movq_cfi rsi, RSI+16-ARGOFFSET
309 movq_cfi rdx, RDX+16-ARGOFFSET
310 movq_cfi rcx, RCX+16-ARGOFFSET
311 movq_cfi rax, RAX+16-ARGOFFSET
312 movq_cfi r8, R8+16-ARGOFFSET
313 movq_cfi r9, R9+16-ARGOFFSET
314 movq_cfi r10, R10+16-ARGOFFSET
315 movq_cfi r11, R11+16-ARGOFFSET
317 leaq -ARGOFFSET+16(%rsp),%rdi /* arg1 for handler */
318 movq_cfi rbp, 8 /* push %rbp */
319 leaq 8(%rsp), %rbp /* mov %rsp, %ebp */
324 * irq_count is used to check if a CPU is already on an interrupt stack
325 * or not. While this is essentially redundant with preempt_count it is
326 * a little cheaper to use a separate counter in the PDA (short of
327 * moving irq_enter into assembly, which would be too much work)
329 1: incl PER_CPU_VAR(irq_count)
331 popq_cfi %rax /* move return address... */
332 mov PER_CPU_VAR(irq_stack_ptr),%rsp
334 pushq_cfi %rbp /* backlink for unwinder */
335 pushq_cfi %rax /* ... to the new stack */
337 * We entered an interrupt context - irqs are off:
345 PARTIAL_FRAME 1 REST_SKIP+8
346 movq 5*8+16(%rsp), %r11 /* save return address */
353 movq %r11, 8(%rsp) /* return address */
354 FIXUP_TOP_OF_STACK %r11, 16
359 /* save complete stack frame */
360 .pushsection .kprobes.text, "ax"
380 movl $MSR_GS_BASE,%ecx
383 js 1f /* negative -> in kernel */
392 * A newly forked process directly context switches into this address.
394 * rdi: prev task we switched from
399 LOCK ; btr $TIF_FORK,TI_flags(%r8)
401 push kernel_eflags(%rip)
402 CFI_ADJUST_CFA_OFFSET 8
403 popf # reset kernel eflags
404 CFI_ADJUST_CFA_OFFSET -8
406 call schedule_tail # rdi: 'prev' task parameter
408 GET_THREAD_INFO(%rcx)
412 testl $3, CS-ARGOFFSET(%rsp) # from kernel_thread?
413 je int_ret_from_sys_call
415 testl $_TIF_IA32, TI_flags(%rcx) # 32-bit compat task needs IRET
416 jnz int_ret_from_sys_call
418 RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
419 jmp ret_from_sys_call # go to the SYSRET fastpath
425 * System call entry. Upto 6 arguments in registers are supported.
427 * SYSCALL does not save anything on the stack and does not change the
433 * rax system call number
435 * rcx return address for syscall/sysret, C arg3
438 * r10 arg3 (--> moved to rcx for C)
441 * r11 eflags for syscall/sysret, temporary for C
442 * r12-r15,rbp,rbx saved by C code, not touched.
444 * Interrupts are off on entry.
445 * Only called from user space.
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.
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.
458 CFI_DEF_CFA rsp,KERNEL_STACK_OFFSET
460 /*CFI_REGISTER rflags,r11*/
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.
467 ENTRY(system_call_after_swapgs)
469 movq %rsp,PER_CPU_VAR(old_rsp)
470 movq PER_CPU_VAR(kernel_stack),%rsp
472 * No need to follow this irqs off/on section - it's straight
475 ENABLE_INTERRUPTS(CLBR_NONE)
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)
483 system_call_fastpath:
484 cmpq $__NR_syscall_max,%rax
487 call *sys_call_table(,%rax,8) # XXX: rip relative
488 movq %rax,RAX-ARGOFFSET(%rsp)
490 * Syscall return path ending with SYSRET (fast path)
491 * Has incomplete stack frame and undefined top of stack.
494 movl $_TIF_ALLWORK_MASK,%edi
498 GET_THREAD_INFO(%rcx)
499 DISABLE_INTERRUPTS(CLBR_NONE)
501 movl TI_flags(%rcx),%edx
506 * sysretq will re-enable interrupts:
509 movq RIP-ARGOFFSET(%rsp),%rcx
511 RESTORE_ARGS 0,-ARG_SKIP,1
512 /*CFI_REGISTER rflags,r11*/
513 movq PER_CPU_VAR(old_rsp), %rsp
517 /* Handle reschedules */
518 /* edx: work, edi: workmask */
520 bt $TIF_NEED_RESCHED,%edx
523 ENABLE_INTERRUPTS(CLBR_NONE)
525 CFI_ADJUST_CFA_OFFSET 8
528 CFI_ADJUST_CFA_OFFSET -8
531 /* Handle a signal */
534 ENABLE_INTERRUPTS(CLBR_NONE)
535 #ifdef CONFIG_AUDITSYSCALL
536 bt $TIF_SYSCALL_AUDIT,%edx
540 * We have a signal, or exit tracing or single-step.
541 * These all wind up with the iret return path anyway,
542 * so just join that path right now.
544 FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
545 jmp int_check_syscall_exit_work
548 movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
549 jmp ret_from_sys_call
551 #ifdef CONFIG_AUDITSYSCALL
553 * Fast path for syscall audit without full syscall trace.
554 * We just call audit_syscall_entry() directly, and then
555 * jump back to the normal fast path.
558 movq %r10,%r9 /* 6th arg: 4th syscall arg */
559 movq %rdx,%r8 /* 5th arg: 3rd syscall arg */
560 movq %rsi,%rcx /* 4th arg: 2nd syscall arg */
561 movq %rdi,%rdx /* 3rd arg: 1st syscall arg */
562 movq %rax,%rsi /* 2nd arg: syscall number */
563 movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */
564 call audit_syscall_entry
565 LOAD_ARGS 0 /* reload call-clobbered registers */
566 jmp system_call_fastpath
569 * Return fast path for syscall audit. Call audit_syscall_exit()
570 * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
574 movq %rax,%rsi /* second arg, syscall return value */
575 cmpq $0,%rax /* is it < 0? */
576 setl %al /* 1 if so, 0 if not */
577 movzbl %al,%edi /* zero-extend that into %edi */
578 inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
579 call audit_syscall_exit
580 movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
582 #endif /* CONFIG_AUDITSYSCALL */
584 /* Do syscall tracing */
586 #ifdef CONFIG_AUDITSYSCALL
587 testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
591 movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
592 FIXUP_TOP_OF_STACK %rdi
594 call syscall_trace_enter
596 * Reload arg registers from stack in case ptrace changed them.
597 * We don't reload %rax because syscall_trace_enter() returned
598 * the value it wants us to use in the table lookup.
600 LOAD_ARGS ARGOFFSET, 1
602 cmpq $__NR_syscall_max,%rax
603 ja int_ret_from_sys_call /* RAX(%rsp) set to -ENOSYS above */
604 movq %r10,%rcx /* fixup for C */
605 call *sys_call_table(,%rax,8)
606 movq %rax,RAX-ARGOFFSET(%rsp)
607 /* Use IRET because user could have changed frame */
610 * Syscall return path ending with IRET.
611 * Has correct top of stack, but partial stack frame.
613 GLOBAL(int_ret_from_sys_call)
614 DISABLE_INTERRUPTS(CLBR_NONE)
616 testl $3,CS-ARGOFFSET(%rsp)
617 je retint_restore_args
618 movl $_TIF_ALLWORK_MASK,%edi
619 /* edi: mask to check */
620 GLOBAL(int_with_check)
622 GET_THREAD_INFO(%rcx)
623 movl TI_flags(%rcx),%edx
626 andl $~TS_COMPAT,TI_status(%rcx)
629 /* Either reschedule or signal or syscall exit tracking needed. */
630 /* First do a reschedule test. */
631 /* edx: work, edi: workmask */
633 bt $TIF_NEED_RESCHED,%edx
636 ENABLE_INTERRUPTS(CLBR_NONE)
638 CFI_ADJUST_CFA_OFFSET 8
641 CFI_ADJUST_CFA_OFFSET -8
642 DISABLE_INTERRUPTS(CLBR_NONE)
646 /* handle signals and tracing -- both require a full stack frame */
649 ENABLE_INTERRUPTS(CLBR_NONE)
650 int_check_syscall_exit_work:
652 /* Check for syscall exit trace */
653 testl $_TIF_WORK_SYSCALL_EXIT,%edx
656 CFI_ADJUST_CFA_OFFSET 8
657 leaq 8(%rsp),%rdi # &ptregs -> arg1
658 call syscall_trace_leave
660 CFI_ADJUST_CFA_OFFSET -8
661 andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
665 testl $_TIF_DO_NOTIFY_MASK,%edx
667 movq %rsp,%rdi # &ptregs -> arg1
668 xorl %esi,%esi # oldset -> arg2
669 call do_notify_resume
670 1: movl $_TIF_WORK_MASK,%edi
673 DISABLE_INTERRUPTS(CLBR_NONE)
680 * Certain special system calls that need to save a complete full stack frame.
682 .macro PTREGSCALL label,func,arg
684 PARTIAL_FRAME 1 8 /* offset 8: return address */
685 subq $REST_SKIP, %rsp
686 CFI_ADJUST_CFA_OFFSET REST_SKIP
688 DEFAULT_FRAME 0 8 /* offset 8: return address */
689 leaq 8(%rsp), \arg /* pt_regs pointer */
691 jmp ptregscall_common
696 PTREGSCALL stub_clone, sys_clone, %r8
697 PTREGSCALL stub_fork, sys_fork, %rdi
698 PTREGSCALL stub_vfork, sys_vfork, %rdi
699 PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
700 PTREGSCALL stub_iopl, sys_iopl, %rsi
702 ENTRY(ptregscall_common)
703 DEFAULT_FRAME 1 8 /* offset 8: return address */
704 RESTORE_TOP_OF_STACK %r11, 8
705 movq_cfi_restore R15+8, r15
706 movq_cfi_restore R14+8, r14
707 movq_cfi_restore R13+8, r13
708 movq_cfi_restore R12+8, r12
709 movq_cfi_restore RBP+8, rbp
710 movq_cfi_restore RBX+8, rbx
711 ret $REST_SKIP /* pop extended registers */
713 END(ptregscall_common)
718 CFI_ADJUST_CFA_OFFSET -8
719 CFI_REGISTER rip, r11
721 FIXUP_TOP_OF_STACK %r11
724 RESTORE_TOP_OF_STACK %r11
727 jmp int_ret_from_sys_call
732 * sigreturn is special because it needs to restore all registers on return.
733 * This cannot be done with SYSRET, so use the IRET return path instead.
735 ENTRY(stub_rt_sigreturn)
738 CFI_ADJUST_CFA_OFFSET -8
741 FIXUP_TOP_OF_STACK %r11
742 call sys_rt_sigreturn
743 movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
745 jmp int_ret_from_sys_call
747 END(stub_rt_sigreturn)
750 * Build the entry stubs and pointer table with some assembler magic.
751 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
752 * single cache line on all modern x86 implementations.
754 .section .init.rodata,"a"
758 .p2align CONFIG_X86_L1_CACHE_SHIFT
759 ENTRY(irq_entries_start)
761 vector=FIRST_EXTERNAL_VECTOR
762 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
765 .if vector < NR_VECTORS
766 .if vector <> FIRST_EXTERNAL_VECTOR
767 CFI_ADJUST_CFA_OFFSET -8
769 1: pushq $(~vector+0x80) /* Note: always in signed byte range */
770 CFI_ADJUST_CFA_OFFSET 8
771 .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
780 2: jmp common_interrupt
783 END(irq_entries_start)
790 * Interrupt entry/exit.
792 * Interrupt entry points save only callee clobbered registers in fast path.
794 * Entry runs with interrupts off.
797 /* 0(%rsp): ~(interrupt number) */
798 .macro interrupt func
800 CFI_ADJUST_CFA_OFFSET 10*8
807 * Interrupt entry/exit should be protected against kprobes
809 .pushsection .kprobes.text, "ax"
811 * The interrupt stubs push (~vector+0x80) onto the stack and
812 * then jump to common_interrupt.
814 .p2align CONFIG_X86_L1_CACHE_SHIFT
817 addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
819 /* 0(%rsp): old_rsp-ARGOFFSET */
821 DISABLE_INTERRUPTS(CLBR_NONE)
823 decl PER_CPU_VAR(irq_count)
825 CFI_DEF_CFA_REGISTER rsp
826 CFI_ADJUST_CFA_OFFSET -8
828 GET_THREAD_INFO(%rcx)
829 testl $3,CS-ARGOFFSET(%rsp)
832 /* Interrupt came from user space */
834 * Has a correct top of stack, but a partial stack frame
835 * %rcx: thread info. Interrupts off.
837 retint_with_reschedule:
838 movl $_TIF_WORK_MASK,%edi
841 movl TI_flags(%rcx),%edx
846 retint_swapgs: /* return to user-space */
848 * The iretq could re-enable interrupts:
850 DISABLE_INTERRUPTS(CLBR_ANY)
855 retint_restore_args: /* return to kernel space */
856 DISABLE_INTERRUPTS(CLBR_ANY)
858 * The iretq could re-enable interrupts:
867 .section __ex_table, "a"
868 .quad irq_return, bad_iret
871 #ifdef CONFIG_PARAVIRT
875 .section __ex_table,"a"
876 .quad native_iret, bad_iret
883 * The iret traps when the %cs or %ss being restored is bogus.
884 * We've lost the original trap vector and error code.
885 * #GPF is the most likely one to get for an invalid selector.
886 * So pretend we completed the iret and took the #GPF in user mode.
888 * We are now running with the kernel GS after exception recovery.
889 * But error_entry expects us to have user GS to match the user %cs,
895 jmp general_protection
899 /* edi: workmask, edx: work */
902 bt $TIF_NEED_RESCHED,%edx
905 ENABLE_INTERRUPTS(CLBR_NONE)
907 CFI_ADJUST_CFA_OFFSET 8
910 CFI_ADJUST_CFA_OFFSET -8
911 GET_THREAD_INFO(%rcx)
912 DISABLE_INTERRUPTS(CLBR_NONE)
917 testl $_TIF_DO_NOTIFY_MASK,%edx
920 ENABLE_INTERRUPTS(CLBR_NONE)
922 movq $-1,ORIG_RAX(%rsp)
923 xorl %esi,%esi # oldset
924 movq %rsp,%rdi # &pt_regs
925 call do_notify_resume
927 DISABLE_INTERRUPTS(CLBR_NONE)
929 GET_THREAD_INFO(%rcx)
930 jmp retint_with_reschedule
932 #ifdef CONFIG_PREEMPT
933 /* Returning to kernel space. Check if we need preemption */
934 /* rcx: threadinfo. interrupts off. */
936 cmpl $0,TI_preempt_count(%rcx)
937 jnz retint_restore_args
938 bt $TIF_NEED_RESCHED,TI_flags(%rcx)
939 jnc retint_restore_args
940 bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */
941 jnc retint_restore_args
942 call preempt_schedule_irq
947 END(common_interrupt)
949 * End of kprobes section
956 .macro apicinterrupt num sym do_sym
960 CFI_ADJUST_CFA_OFFSET 8
968 apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \
969 irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt
970 apicinterrupt REBOOT_VECTOR \
971 reboot_interrupt smp_reboot_interrupt
975 apicinterrupt UV_BAU_MESSAGE \
976 uv_bau_message_intr1 uv_bau_message_interrupt
978 apicinterrupt LOCAL_TIMER_VECTOR \
979 apic_timer_interrupt smp_apic_timer_interrupt
980 apicinterrupt X86_PLATFORM_IPI_VECTOR \
981 x86_platform_ipi smp_x86_platform_ipi
984 apicinterrupt INVALIDATE_TLB_VECTOR_START+0 \
985 invalidate_interrupt0 smp_invalidate_interrupt
986 apicinterrupt INVALIDATE_TLB_VECTOR_START+1 \
987 invalidate_interrupt1 smp_invalidate_interrupt
988 apicinterrupt INVALIDATE_TLB_VECTOR_START+2 \
989 invalidate_interrupt2 smp_invalidate_interrupt
990 apicinterrupt INVALIDATE_TLB_VECTOR_START+3 \
991 invalidate_interrupt3 smp_invalidate_interrupt
992 apicinterrupt INVALIDATE_TLB_VECTOR_START+4 \
993 invalidate_interrupt4 smp_invalidate_interrupt
994 apicinterrupt INVALIDATE_TLB_VECTOR_START+5 \
995 invalidate_interrupt5 smp_invalidate_interrupt
996 apicinterrupt INVALIDATE_TLB_VECTOR_START+6 \
997 invalidate_interrupt6 smp_invalidate_interrupt
998 apicinterrupt INVALIDATE_TLB_VECTOR_START+7 \
999 invalidate_interrupt7 smp_invalidate_interrupt
1002 apicinterrupt THRESHOLD_APIC_VECTOR \
1003 threshold_interrupt smp_threshold_interrupt
1004 apicinterrupt THERMAL_APIC_VECTOR \
1005 thermal_interrupt smp_thermal_interrupt
1007 #ifdef CONFIG_X86_MCE
1008 apicinterrupt MCE_SELF_VECTOR \
1009 mce_self_interrupt smp_mce_self_interrupt
1013 apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \
1014 call_function_single_interrupt smp_call_function_single_interrupt
1015 apicinterrupt CALL_FUNCTION_VECTOR \
1016 call_function_interrupt smp_call_function_interrupt
1017 apicinterrupt RESCHEDULE_VECTOR \
1018 reschedule_interrupt smp_reschedule_interrupt
1021 apicinterrupt ERROR_APIC_VECTOR \
1022 error_interrupt smp_error_interrupt
1023 apicinterrupt SPURIOUS_APIC_VECTOR \
1024 spurious_interrupt smp_spurious_interrupt
1026 #ifdef CONFIG_PERF_EVENTS
1027 apicinterrupt LOCAL_PENDING_VECTOR \
1028 perf_pending_interrupt smp_perf_pending_interrupt
1032 * Exception entry points.
1034 .macro zeroentry sym do_sym
1037 PARAVIRT_ADJUST_EXCEPTION_FRAME
1038 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1040 CFI_ADJUST_CFA_OFFSET 15*8
1043 movq %rsp,%rdi /* pt_regs pointer */
1044 xorl %esi,%esi /* no error code */
1046 jmp error_exit /* %ebx: no swapgs flag */
1051 .macro paranoidzeroentry sym do_sym
1054 PARAVIRT_ADJUST_EXCEPTION_FRAME
1055 pushq $-1 /* ORIG_RAX: no syscall to restart */
1056 CFI_ADJUST_CFA_OFFSET 8
1060 movq %rsp,%rdi /* pt_regs pointer */
1061 xorl %esi,%esi /* no error code */
1063 jmp paranoid_exit /* %ebx: no swapgs flag */
1068 .macro paranoidzeroentry_ist sym do_sym ist
1071 PARAVIRT_ADJUST_EXCEPTION_FRAME
1072 pushq $-1 /* ORIG_RAX: no syscall to restart */
1073 CFI_ADJUST_CFA_OFFSET 8
1077 movq %rsp,%rdi /* pt_regs pointer */
1078 xorl %esi,%esi /* no error code */
1079 PER_CPU(init_tss, %rbp)
1080 subq $EXCEPTION_STKSZ, TSS_ist + (\ist - 1) * 8(%rbp)
1082 addq $EXCEPTION_STKSZ, TSS_ist + (\ist - 1) * 8(%rbp)
1083 jmp paranoid_exit /* %ebx: no swapgs flag */
1088 .macro errorentry sym do_sym
1091 PARAVIRT_ADJUST_EXCEPTION_FRAME
1093 CFI_ADJUST_CFA_OFFSET 15*8
1096 movq %rsp,%rdi /* pt_regs pointer */
1097 movq ORIG_RAX(%rsp),%rsi /* get error code */
1098 movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
1100 jmp error_exit /* %ebx: no swapgs flag */
1105 /* error code is on the stack already */
1106 .macro paranoiderrorentry sym do_sym
1109 PARAVIRT_ADJUST_EXCEPTION_FRAME
1111 CFI_ADJUST_CFA_OFFSET 15*8
1115 movq %rsp,%rdi /* pt_regs pointer */
1116 movq ORIG_RAX(%rsp),%rsi /* get error code */
1117 movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
1119 jmp paranoid_exit /* %ebx: no swapgs flag */
1124 zeroentry divide_error do_divide_error
1125 zeroentry overflow do_overflow
1126 zeroentry bounds do_bounds
1127 zeroentry invalid_op do_invalid_op
1128 zeroentry device_not_available do_device_not_available
1129 paranoiderrorentry double_fault do_double_fault
1130 zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun
1131 errorentry invalid_TSS do_invalid_TSS
1132 errorentry segment_not_present do_segment_not_present
1133 zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
1134 zeroentry coprocessor_error do_coprocessor_error
1135 errorentry alignment_check do_alignment_check
1136 zeroentry simd_coprocessor_error do_simd_coprocessor_error
1138 /* Reload gs selector with exception handling */
1139 /* edi: new selector */
1140 ENTRY(native_load_gs_index)
1143 CFI_ADJUST_CFA_OFFSET 8
1144 DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
1148 2: mfence /* workaround */
1151 CFI_ADJUST_CFA_OFFSET -8
1154 END(native_load_gs_index)
1156 .section __ex_table,"a"
1158 .quad gs_change,bad_gs
1160 .section .fixup,"ax"
1161 /* running with kernelgs */
1163 SWAPGS /* switch back to user gs */
1170 * Create a kernel thread.
1172 * C extern interface:
1173 * extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
1175 * asm input arguments:
1176 * rdi: fn, rsi: arg, rdx: flags
1178 ENTRY(kernel_thread)
1180 FAKE_STACK_FRAME $child_rip
1183 # rdi: flags, rsi: usp, rdx: will be &pt_regs
1185 orq kernel_thread_flags(%rip),%rdi
1198 * It isn't worth to check for reschedule here,
1199 * so internally to the x86_64 port you can rely on kernel_thread()
1200 * not to reschedule the child before returning, this avoids the need
1201 * of hacks for example to fork off the per-CPU idle tasks.
1202 * [Hopefully no generic code relies on the reschedule -AK]
1211 pushq $0 # fake return address
1214 * Here we are in the child and the registers are set as they were
1215 * at kernel_thread() invocation in the parent.
1223 ud2 # padding for call trace
1228 * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
1230 * C extern interface:
1231 * extern long execve(char *name, char **argv, char **envp)
1233 * asm input arguments:
1234 * rdi: name, rsi: argv, rdx: envp
1236 * We want to fallback into:
1237 * extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs *regs)
1239 * do_sys_execve asm fallback arguments:
1240 * rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
1242 ENTRY(kernel_execve)
1248 movq %rax, RAX(%rsp)
1251 je int_ret_from_sys_call
1258 /* Call softirq on interrupt stack. Interrupts are off. */
1262 CFI_ADJUST_CFA_OFFSET 8
1263 CFI_REL_OFFSET rbp,0
1265 CFI_DEF_CFA_REGISTER rbp
1266 incl PER_CPU_VAR(irq_count)
1267 cmove PER_CPU_VAR(irq_stack_ptr),%rsp
1268 push %rbp # backlink for old unwinder
1271 CFI_DEF_CFA_REGISTER rsp
1272 CFI_ADJUST_CFA_OFFSET -8
1273 decl PER_CPU_VAR(irq_count)
1279 zeroentry xen_hypervisor_callback xen_do_hypervisor_callback
1282 * A note on the "critical region" in our callback handler.
1283 * We want to avoid stacking callback handlers due to events occurring
1284 * during handling of the last event. To do this, we keep events disabled
1285 * until we've done all processing. HOWEVER, we must enable events before
1286 * popping the stack frame (can't be done atomically) and so it would still
1287 * be possible to get enough handler activations to overflow the stack.
1288 * Although unlikely, bugs of that kind are hard to track down, so we'd
1289 * like to avoid the possibility.
1290 * So, on entry to the handler we detect whether we interrupted an
1291 * existing activation in its critical region -- if so, we pop the current
1292 * activation and restart the handler using the previous one.
1294 ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
1297 * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
1298 * see the correct pointer to the pt_regs
1300 movq %rdi, %rsp # we don't return, adjust the stack frame
1303 11: incl PER_CPU_VAR(irq_count)
1305 CFI_DEF_CFA_REGISTER rbp
1306 cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
1307 pushq %rbp # backlink for old unwinder
1308 call xen_evtchn_do_upcall
1310 CFI_DEF_CFA_REGISTER rsp
1311 decl PER_CPU_VAR(irq_count)
1314 END(do_hypervisor_callback)
1317 * Hypervisor uses this for application faults while it executes.
1318 * We get here for two reasons:
1319 * 1. Fault while reloading DS, ES, FS or GS
1320 * 2. Fault while executing IRET
1321 * Category 1 we do not need to fix up as Xen has already reloaded all segment
1322 * registers that could be reloaded and zeroed the others.
1323 * Category 2 we fix up by killing the current process. We cannot use the
1324 * normal Linux return path in this case because if we use the IRET hypercall
1325 * to pop the stack frame we end up in an infinite loop of failsafe callbacks.
1326 * We distinguish between categories by comparing each saved segment register
1327 * with its current contents: any discrepancy means we in category 1.
1329 ENTRY(xen_failsafe_callback)
1331 /*CFI_REL_OFFSET gs,GS*/
1332 /*CFI_REL_OFFSET fs,FS*/
1333 /*CFI_REL_OFFSET es,ES*/
1334 /*CFI_REL_OFFSET ds,DS*/
1335 CFI_REL_OFFSET r11,8
1336 CFI_REL_OFFSET rcx,0
1350 /* All segments match their saved values => Category 2 (Bad IRET). */
1356 CFI_ADJUST_CFA_OFFSET -0x30
1357 pushq_cfi $0 /* RIP */
1360 jmp general_protection
1362 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
1368 CFI_ADJUST_CFA_OFFSET -0x30
1373 END(xen_failsafe_callback)
1375 #endif /* CONFIG_XEN */
1378 * Some functions should be protected against kprobes
1380 .pushsection .kprobes.text, "ax"
1382 paranoidzeroentry_ist debug do_debug DEBUG_STACK
1383 paranoidzeroentry_ist int3 do_int3 DEBUG_STACK
1384 paranoiderrorentry stack_segment do_stack_segment
1386 zeroentry xen_debug do_debug
1387 zeroentry xen_int3 do_int3
1388 errorentry xen_stack_segment do_stack_segment
1390 errorentry general_protection do_general_protection
1391 errorentry page_fault do_page_fault
1392 #ifdef CONFIG_X86_MCE
1393 paranoidzeroentry machine_check *machine_check_vector(%rip)
1397 * "Paranoid" exit path from exception stack.
1398 * Paranoid because this is used by NMIs and cannot take
1399 * any kernel state for granted.
1400 * We don't do kernel preemption checks here, because only
1401 * NMI should be common and it does not enable IRQs and
1402 * cannot get reschedule ticks.
1404 * "trace" is 0 for the NMI handler only, because irq-tracing
1405 * is fundamentally NMI-unsafe. (we cannot change the soft and
1406 * hard flags at once, atomically)
1409 /* ebx: no swapgs flag */
1410 ENTRY(paranoid_exit)
1412 DISABLE_INTERRUPTS(CLBR_NONE)
1414 testl %ebx,%ebx /* swapgs needed? */
1415 jnz paranoid_restore
1417 jnz paranoid_userspace
1428 GET_THREAD_INFO(%rcx)
1429 movl TI_flags(%rcx),%ebx
1430 andl $_TIF_WORK_MASK,%ebx
1432 movq %rsp,%rdi /* &pt_regs */
1434 movq %rax,%rsp /* switch stack for scheduling */
1435 testl $_TIF_NEED_RESCHED,%ebx
1436 jnz paranoid_schedule
1437 movl %ebx,%edx /* arg3: thread flags */
1439 ENABLE_INTERRUPTS(CLBR_NONE)
1440 xorl %esi,%esi /* arg2: oldset */
1441 movq %rsp,%rdi /* arg1: &pt_regs */
1442 call do_notify_resume
1443 DISABLE_INTERRUPTS(CLBR_NONE)
1445 jmp paranoid_userspace
1448 ENABLE_INTERRUPTS(CLBR_ANY)
1450 DISABLE_INTERRUPTS(CLBR_ANY)
1452 jmp paranoid_userspace
1457 * Exception entry point. This expects an error code/orig_rax on the stack.
1458 * returns in "no swapgs flag" in %ebx.
1462 CFI_ADJUST_CFA_OFFSET 15*8
1463 /* oldrax contains error code */
1482 je error_kernelspace
1491 * There are two places in the kernel that can potentially fault with
1492 * usergs. Handle them here. The exception handlers after iret run with
1493 * kernel gs again, so don't set the user space flag. B stepping K8s
1494 * sometimes report an truncated RIP for IRET exceptions returning to
1495 * compat mode. Check for these here too.
1499 leaq irq_return(%rip),%rcx
1500 cmpq %rcx,RIP+8(%rsp)
1502 movl %ecx,%eax /* zero extend */
1503 cmpq %rax,RIP+8(%rsp)
1505 cmpq $gs_change,RIP+8(%rsp)
1510 /* Fix truncated RIP */
1511 movq %rcx,RIP+8(%rsp)
1516 /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
1521 DISABLE_INTERRUPTS(CLBR_NONE)
1523 GET_THREAD_INFO(%rcx)
1526 LOCKDEP_SYS_EXIT_IRQ
1527 movl TI_flags(%rcx),%edx
1528 movl $_TIF_WORK_MASK,%edi
1536 /* runs on exception stack */
1539 PARAVIRT_ADJUST_EXCEPTION_FRAME
1542 CFI_ADJUST_CFA_OFFSET 15*8
1545 /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
1549 #ifdef CONFIG_TRACE_IRQFLAGS
1550 /* paranoidexit; without TRACE_IRQS_OFF */
1551 /* ebx: no swapgs flag */
1552 DISABLE_INTERRUPTS(CLBR_NONE)
1553 testl %ebx,%ebx /* swapgs needed? */
1563 GET_THREAD_INFO(%rcx)
1564 movl TI_flags(%rcx),%ebx
1565 andl $_TIF_WORK_MASK,%ebx
1567 movq %rsp,%rdi /* &pt_regs */
1569 movq %rax,%rsp /* switch stack for scheduling */
1570 testl $_TIF_NEED_RESCHED,%ebx
1572 movl %ebx,%edx /* arg3: thread flags */
1573 ENABLE_INTERRUPTS(CLBR_NONE)
1574 xorl %esi,%esi /* arg2: oldset */
1575 movq %rsp,%rdi /* arg1: &pt_regs */
1576 call do_notify_resume
1577 DISABLE_INTERRUPTS(CLBR_NONE)
1580 ENABLE_INTERRUPTS(CLBR_ANY)
1582 DISABLE_INTERRUPTS(CLBR_ANY)
1591 ENTRY(ignore_sysret)
1599 * End of kprobes section