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 * Some of this is documented in Documentation/x86/entry_64.txt
14 * NOTE: This code handles signal-recognition, which happens every time
15 * after an interrupt and after each system call.
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.
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.
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.
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>
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>
59 #include <linux/err.h>
61 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
62 #include <linux/elf-em.h>
63 #define AUDIT_ARCH_X86_64 (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
64 #define __AUDIT_ARCH_64BIT 0x80000000
65 #define __AUDIT_ARCH_LE 0x40000000
68 .section .entry.text, "ax"
70 #ifdef CONFIG_FUNCTION_TRACER
71 #ifdef CONFIG_DYNAMIC_FTRACE
77 cmpl $0, function_trace_stop
84 subq $MCOUNT_INSN_SIZE, %rdi
91 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
92 GLOBAL(ftrace_graph_call)
100 #else /* ! CONFIG_DYNAMIC_FTRACE */
102 cmpl $0, function_trace_stop
105 cmpq $ftrace_stub, ftrace_trace_function
108 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
109 cmpq $ftrace_stub, ftrace_graph_return
110 jnz ftrace_graph_caller
112 cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
113 jnz ftrace_graph_caller
122 movq 0x38(%rsp), %rdi
124 subq $MCOUNT_INSN_SIZE, %rdi
126 call *ftrace_trace_function
132 #endif /* CONFIG_DYNAMIC_FTRACE */
133 #endif /* CONFIG_FUNCTION_TRACER */
135 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
136 ENTRY(ftrace_graph_caller)
137 cmpl $0, function_trace_stop
143 movq 0x38(%rsp), %rsi
145 subq $MCOUNT_INSN_SIZE, %rsi
147 call prepare_ftrace_return
152 END(ftrace_graph_caller)
154 GLOBAL(return_to_handler)
157 /* Save the return values */
162 call ftrace_return_to_handler
172 #ifndef CONFIG_PREEMPT
173 #define retint_kernel retint_restore_args
176 #ifdef CONFIG_PARAVIRT
177 ENTRY(native_usergs_sysret64)
180 ENDPROC(native_usergs_sysret64)
181 #endif /* CONFIG_PARAVIRT */
184 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
185 #ifdef CONFIG_TRACE_IRQFLAGS
186 bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */
194 * C code is not supposed to know about undefined top of stack. Every time
195 * a C function with an pt_regs argument is called from the SYSCALL based
196 * fast path FIXUP_TOP_OF_STACK is needed.
197 * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
201 /* %rsp:at FRAMEEND */
202 .macro FIXUP_TOP_OF_STACK tmp offset=0
203 movq PER_CPU_VAR(old_rsp),\tmp
204 movq \tmp,RSP+\offset(%rsp)
205 movq $__USER_DS,SS+\offset(%rsp)
206 movq $__USER_CS,CS+\offset(%rsp)
207 movq $-1,RCX+\offset(%rsp)
208 movq R11+\offset(%rsp),\tmp /* get eflags */
209 movq \tmp,EFLAGS+\offset(%rsp)
212 .macro RESTORE_TOP_OF_STACK tmp offset=0
213 movq RSP+\offset(%rsp),\tmp
214 movq \tmp,PER_CPU_VAR(old_rsp)
215 movq EFLAGS+\offset(%rsp),\tmp
216 movq \tmp,R11+\offset(%rsp)
219 .macro FAKE_STACK_FRAME child_rip
220 /* push in order ss, rsp, eflags, cs, rip */
222 pushq_cfi $__KERNEL_DS /* ss */
223 /*CFI_REL_OFFSET ss,0*/
224 pushq_cfi %rax /* rsp */
226 pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_BIT1) /* eflags - interrupts on */
227 /*CFI_REL_OFFSET rflags,0*/
228 pushq_cfi $__KERNEL_CS /* cs */
229 /*CFI_REL_OFFSET cs,0*/
230 pushq_cfi \child_rip /* rip */
232 pushq_cfi %rax /* orig rax */
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 */
306 /* start from rbp in pt_regs and jump over */
307 movq_cfi rdi, RDI-RBP
308 movq_cfi rsi, RSI-RBP
309 movq_cfi rdx, RDX-RBP
310 movq_cfi rcx, RCX-RBP
311 movq_cfi rax, RAX-RBP
314 movq_cfi r10, R10-RBP
315 movq_cfi r11, R11-RBP
317 /* Save rbp so that we can unwind from get_irq_regs() */
320 /* Save previous stack value */
323 leaq -RBP(%rsp),%rdi /* arg1 for handler */
324 testl $3, CS-RBP(%rsi)
328 * irq_count is used to check if a CPU is already on an interrupt stack
329 * or not. While this is essentially redundant with preempt_count it is
330 * a little cheaper to use a separate counter in the PDA (short of
331 * moving irq_enter into assembly, which would be too much work)
333 1: incl PER_CPU_VAR(irq_count)
334 cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
335 CFI_DEF_CFA_REGISTER rsi
337 /* Store previous stack value */
339 CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \
340 0x77 /* DW_OP_breg7 */, 0, \
341 0x06 /* DW_OP_deref */, \
342 0x08 /* DW_OP_const1u */, SS+8-RBP, \
343 0x22 /* DW_OP_plus */
344 /* We entered an interrupt context - irqs are off: */
349 PARTIAL_FRAME 1 REST_SKIP+8
350 movq 5*8+16(%rsp), %r11 /* save return address */
357 movq %r11, 8(%rsp) /* return address */
358 FIXUP_TOP_OF_STACK %r11, 16
363 /* save complete stack frame */
364 .pushsection .kprobes.text, "ax"
384 movl $MSR_GS_BASE,%ecx
387 js 1f /* negative -> in kernel */
396 * A newly forked process directly context switches into this address.
398 * rdi: prev task we switched from
403 LOCK ; btr $TIF_FORK,TI_flags(%r8)
405 pushq_cfi kernel_eflags(%rip)
406 popfq_cfi # reset kernel eflags
408 call schedule_tail # rdi: 'prev' task parameter
410 GET_THREAD_INFO(%rcx)
414 testl $3, CS-ARGOFFSET(%rsp) # from kernel_thread?
415 jz retint_restore_args
417 testl $_TIF_IA32, TI_flags(%rcx) # 32-bit compat task needs IRET
418 jnz int_ret_from_sys_call
420 RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
421 jmp ret_from_sys_call # go to the SYSRET fastpath
427 * System call entry. Up to 6 arguments in registers are supported.
429 * SYSCALL does not save anything on the stack and does not change the
435 * rax system call number
437 * rcx return address for syscall/sysret, C arg3
440 * r10 arg3 (--> moved to rcx for C)
443 * r11 eflags for syscall/sysret, temporary for C
444 * r12-r15,rbp,rbx saved by C code, not touched.
446 * Interrupts are off on entry.
447 * Only called from user space.
449 * XXX if we had a free scratch register we could save the RSP into the stack frame
450 * and report it properly in ps. Unfortunately we haven't.
452 * When user can change the frames always force IRET. That is because
453 * it deals with uncanonical addresses better. SYSRET has trouble
454 * with them due to bugs in both AMD and Intel CPUs.
460 CFI_DEF_CFA rsp,KERNEL_STACK_OFFSET
462 /*CFI_REGISTER rflags,r11*/
465 * A hypervisor implementation might want to use a label
466 * after the swapgs, so that it can do the swapgs
467 * for the guest and jump here on syscall.
469 GLOBAL(system_call_after_swapgs)
471 movq %rsp,PER_CPU_VAR(old_rsp)
472 movq PER_CPU_VAR(kernel_stack),%rsp
474 * No need to follow this irqs off/on section - it's straight
477 ENABLE_INTERRUPTS(CLBR_NONE)
479 movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
480 movq %rcx,RIP-ARGOFFSET(%rsp)
481 CFI_REL_OFFSET rip,RIP-ARGOFFSET
482 testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
484 system_call_fastpath:
485 #if __SYSCALL_MASK == ~0
486 cmpq $__NR_syscall_max,%rax
488 andl $__SYSCALL_MASK,%eax
489 cmpl $__NR_syscall_max,%eax
493 call *sys_call_table(,%rax,8) # XXX: rip relative
494 movq %rax,RAX-ARGOFFSET(%rsp)
496 * Syscall return path ending with SYSRET (fast path)
497 * Has incomplete stack frame and undefined top of stack.
500 movl $_TIF_ALLWORK_MASK,%edi
504 DISABLE_INTERRUPTS(CLBR_NONE)
506 movl TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET),%edx
511 * sysretq will re-enable interrupts:
514 movq RIP-ARGOFFSET(%rsp),%rcx
516 RESTORE_ARGS 1,-ARG_SKIP,0
517 /*CFI_REGISTER rflags,r11*/
518 movq PER_CPU_VAR(old_rsp), %rsp
522 /* Handle reschedules */
523 /* edx: work, edi: workmask */
525 bt $TIF_NEED_RESCHED,%edx
528 ENABLE_INTERRUPTS(CLBR_NONE)
534 /* Handle a signal */
537 ENABLE_INTERRUPTS(CLBR_NONE)
538 #ifdef CONFIG_AUDITSYSCALL
539 bt $TIF_SYSCALL_AUDIT,%edx
543 * We have a signal, or exit tracing or single-step.
544 * These all wind up with the iret return path anyway,
545 * so just join that path right now.
547 FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
548 jmp int_check_syscall_exit_work
551 movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
552 jmp ret_from_sys_call
554 #ifdef CONFIG_AUDITSYSCALL
556 * Fast path for syscall audit without full syscall trace.
557 * We just call __audit_syscall_entry() directly, and then
558 * jump back to the normal fast path.
561 movq %r10,%r9 /* 6th arg: 4th syscall arg */
562 movq %rdx,%r8 /* 5th arg: 3rd syscall arg */
563 movq %rsi,%rcx /* 4th arg: 2nd syscall arg */
564 movq %rdi,%rdx /* 3rd arg: 1st syscall arg */
565 movq %rax,%rsi /* 2nd arg: syscall number */
566 movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */
567 call __audit_syscall_entry
568 LOAD_ARGS 0 /* reload call-clobbered registers */
569 jmp system_call_fastpath
572 * Return fast path for syscall audit. Call __audit_syscall_exit()
573 * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
577 movq RAX-ARGOFFSET(%rsp),%rsi /* second arg, syscall return value */
578 cmpq $-MAX_ERRNO,%rsi /* is it < -MAX_ERRNO? */
579 setbe %al /* 1 if so, 0 if not */
580 movzbl %al,%edi /* zero-extend that into %edi */
581 call __audit_syscall_exit
582 movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
584 #endif /* CONFIG_AUDITSYSCALL */
586 /* Do syscall tracing */
588 #ifdef CONFIG_AUDITSYSCALL
589 testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
593 movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
594 FIXUP_TOP_OF_STACK %rdi
596 call syscall_trace_enter
598 * Reload arg registers from stack in case ptrace changed them.
599 * We don't reload %rax because syscall_trace_enter() returned
600 * the value it wants us to use in the table lookup.
602 LOAD_ARGS ARGOFFSET, 1
604 #if __SYSCALL_MASK == ~0
605 cmpq $__NR_syscall_max,%rax
607 andl $__SYSCALL_MASK,%eax
608 cmpl $__NR_syscall_max,%eax
610 ja int_ret_from_sys_call /* RAX(%rsp) set to -ENOSYS above */
611 movq %r10,%rcx /* fixup for C */
612 call *sys_call_table(,%rax,8)
613 movq %rax,RAX-ARGOFFSET(%rsp)
614 /* Use IRET because user could have changed frame */
617 * Syscall return path ending with IRET.
618 * Has correct top of stack, but partial stack frame.
620 GLOBAL(int_ret_from_sys_call)
621 DISABLE_INTERRUPTS(CLBR_NONE)
623 movl $_TIF_ALLWORK_MASK,%edi
624 /* edi: mask to check */
625 GLOBAL(int_with_check)
627 GET_THREAD_INFO(%rcx)
628 movl TI_flags(%rcx),%edx
631 andl $~TS_COMPAT,TI_status(%rcx)
634 /* Either reschedule or signal or syscall exit tracking needed. */
635 /* First do a reschedule test. */
636 /* edx: work, edi: workmask */
638 bt $TIF_NEED_RESCHED,%edx
641 ENABLE_INTERRUPTS(CLBR_NONE)
645 DISABLE_INTERRUPTS(CLBR_NONE)
649 /* handle signals and tracing -- both require a full stack frame */
652 ENABLE_INTERRUPTS(CLBR_NONE)
653 int_check_syscall_exit_work:
655 /* Check for syscall exit trace */
656 testl $_TIF_WORK_SYSCALL_EXIT,%edx
659 leaq 8(%rsp),%rdi # &ptregs -> arg1
660 call syscall_trace_leave
662 andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
666 testl $_TIF_DO_NOTIFY_MASK,%edx
668 movq %rsp,%rdi # &ptregs -> arg1
669 xorl %esi,%esi # oldset -> arg2
670 call do_notify_resume
671 1: movl $_TIF_WORK_MASK,%edi
674 DISABLE_INTERRUPTS(CLBR_NONE)
681 * Certain special system calls that need to save a complete full stack frame.
683 .macro PTREGSCALL label,func,arg
685 PARTIAL_FRAME 1 8 /* offset 8: return address */
686 subq $REST_SKIP, %rsp
687 CFI_ADJUST_CFA_OFFSET REST_SKIP
689 DEFAULT_FRAME 0 8 /* offset 8: return address */
690 leaq 8(%rsp), \arg /* pt_regs pointer */
692 jmp ptregscall_common
697 PTREGSCALL stub_clone, sys_clone, %r8
698 PTREGSCALL stub_fork, sys_fork, %rdi
699 PTREGSCALL stub_vfork, sys_vfork, %rdi
700 PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
701 PTREGSCALL stub_iopl, sys_iopl, %rsi
703 ENTRY(ptregscall_common)
704 DEFAULT_FRAME 1 8 /* offset 8: return address */
705 RESTORE_TOP_OF_STACK %r11, 8
706 movq_cfi_restore R15+8, r15
707 movq_cfi_restore R14+8, r14
708 movq_cfi_restore R13+8, r13
709 movq_cfi_restore R12+8, r12
710 movq_cfi_restore RBP+8, rbp
711 movq_cfi_restore RBX+8, rbx
712 ret $REST_SKIP /* pop extended registers */
714 END(ptregscall_common)
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)
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)
749 #ifdef CONFIG_X86_X32_ABI
750 PTREGSCALL stub_x32_sigaltstack, sys32_sigaltstack, %rdx
752 ENTRY(stub_x32_rt_sigreturn)
758 FIXUP_TOP_OF_STACK %r11
759 call sys32_x32_rt_sigreturn
760 movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
762 jmp int_ret_from_sys_call
764 END(stub_x32_rt_sigreturn)
766 ENTRY(stub_x32_execve)
771 FIXUP_TOP_OF_STACK %r11
774 RESTORE_TOP_OF_STACK %r11
777 jmp int_ret_from_sys_call
784 * Build the entry stubs and pointer table with some assembler magic.
785 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
786 * single cache line on all modern x86 implementations.
788 .section .init.rodata,"a"
792 .p2align CONFIG_X86_L1_CACHE_SHIFT
793 ENTRY(irq_entries_start)
795 vector=FIRST_EXTERNAL_VECTOR
796 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
799 .if vector < NR_VECTORS
800 .if vector <> FIRST_EXTERNAL_VECTOR
801 CFI_ADJUST_CFA_OFFSET -8
803 1: pushq_cfi $(~vector+0x80) /* Note: always in signed byte range */
804 .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
813 2: jmp common_interrupt
816 END(irq_entries_start)
823 * Interrupt entry/exit.
825 * Interrupt entry points save only callee clobbered registers in fast path.
827 * Entry runs with interrupts off.
830 /* 0(%rsp): ~(interrupt number) */
831 .macro interrupt func
832 /* reserve pt_regs for scratch regs and rbp */
833 subq $ORIG_RAX-RBP, %rsp
834 CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP
840 * Interrupt entry/exit should be protected against kprobes
842 .pushsection .kprobes.text, "ax"
844 * The interrupt stubs push (~vector+0x80) onto the stack and
845 * then jump to common_interrupt.
847 .p2align CONFIG_X86_L1_CACHE_SHIFT
850 addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
852 /* 0(%rsp): old_rsp-ARGOFFSET */
854 DISABLE_INTERRUPTS(CLBR_NONE)
856 decl PER_CPU_VAR(irq_count)
858 /* Restore saved previous stack */
860 CFI_DEF_CFA rsi,SS+8-RBP /* reg/off reset after def_cfa_expr */
861 leaq ARGOFFSET-RBP(%rsi), %rsp
862 CFI_DEF_CFA_REGISTER rsp
863 CFI_ADJUST_CFA_OFFSET RBP-ARGOFFSET
866 GET_THREAD_INFO(%rcx)
867 testl $3,CS-ARGOFFSET(%rsp)
870 /* Interrupt came from user space */
872 * Has a correct top of stack, but a partial stack frame
873 * %rcx: thread info. Interrupts off.
875 retint_with_reschedule:
876 movl $_TIF_WORK_MASK,%edi
879 movl TI_flags(%rcx),%edx
884 retint_swapgs: /* return to user-space */
886 * The iretq could re-enable interrupts:
888 DISABLE_INTERRUPTS(CLBR_ANY)
893 retint_restore_args: /* return to kernel space */
894 DISABLE_INTERRUPTS(CLBR_ANY)
896 * The iretq could re-enable interrupts:
904 _ASM_EXTABLE(irq_return, bad_iret)
906 #ifdef CONFIG_PARAVIRT
909 _ASM_EXTABLE(native_iret, bad_iret)
915 * The iret traps when the %cs or %ss being restored is bogus.
916 * We've lost the original trap vector and error code.
917 * #GPF is the most likely one to get for an invalid selector.
918 * So pretend we completed the iret and took the #GPF in user mode.
920 * We are now running with the kernel GS after exception recovery.
921 * But error_entry expects us to have user GS to match the user %cs,
927 jmp general_protection
931 /* edi: workmask, edx: work */
934 bt $TIF_NEED_RESCHED,%edx
937 ENABLE_INTERRUPTS(CLBR_NONE)
941 GET_THREAD_INFO(%rcx)
942 DISABLE_INTERRUPTS(CLBR_NONE)
947 testl $_TIF_DO_NOTIFY_MASK,%edx
950 ENABLE_INTERRUPTS(CLBR_NONE)
952 movq $-1,ORIG_RAX(%rsp)
953 xorl %esi,%esi # oldset
954 movq %rsp,%rdi # &pt_regs
955 call do_notify_resume
957 DISABLE_INTERRUPTS(CLBR_NONE)
959 GET_THREAD_INFO(%rcx)
960 jmp retint_with_reschedule
962 #ifdef CONFIG_PREEMPT
963 /* Returning to kernel space. Check if we need preemption */
964 /* rcx: threadinfo. interrupts off. */
966 cmpl $0,TI_preempt_count(%rcx)
967 jnz retint_restore_args
968 bt $TIF_NEED_RESCHED,TI_flags(%rcx)
969 jnc retint_restore_args
970 bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */
971 jnc retint_restore_args
972 call preempt_schedule_irq
977 END(common_interrupt)
979 * End of kprobes section
986 .macro apicinterrupt num sym do_sym
998 apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \
999 irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt
1000 apicinterrupt REBOOT_VECTOR \
1001 reboot_interrupt smp_reboot_interrupt
1004 #ifdef CONFIG_X86_UV
1005 apicinterrupt UV_BAU_MESSAGE \
1006 uv_bau_message_intr1 uv_bau_message_interrupt
1008 apicinterrupt LOCAL_TIMER_VECTOR \
1009 apic_timer_interrupt smp_apic_timer_interrupt
1010 apicinterrupt X86_PLATFORM_IPI_VECTOR \
1011 x86_platform_ipi smp_x86_platform_ipi
1016 .irp idx,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \
1017 16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
1018 .if NUM_INVALIDATE_TLB_VECTORS > \idx
1019 ENTRY(invalidate_interrupt\idx)
1020 pushq_cfi $~(INVALIDATE_TLB_VECTOR_START+\idx)
1021 jmp .Lcommon_invalidate_interrupt0
1022 CFI_ADJUST_CFA_OFFSET -8
1023 END(invalidate_interrupt\idx)
1027 apicinterrupt INVALIDATE_TLB_VECTOR_START, \
1028 invalidate_interrupt0, smp_invalidate_interrupt
1031 apicinterrupt THRESHOLD_APIC_VECTOR \
1032 threshold_interrupt smp_threshold_interrupt
1033 apicinterrupt THERMAL_APIC_VECTOR \
1034 thermal_interrupt smp_thermal_interrupt
1037 apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \
1038 call_function_single_interrupt smp_call_function_single_interrupt
1039 apicinterrupt CALL_FUNCTION_VECTOR \
1040 call_function_interrupt smp_call_function_interrupt
1041 apicinterrupt RESCHEDULE_VECTOR \
1042 reschedule_interrupt smp_reschedule_interrupt
1045 apicinterrupt ERROR_APIC_VECTOR \
1046 error_interrupt smp_error_interrupt
1047 apicinterrupt SPURIOUS_APIC_VECTOR \
1048 spurious_interrupt smp_spurious_interrupt
1050 #ifdef CONFIG_IRQ_WORK
1051 apicinterrupt IRQ_WORK_VECTOR \
1052 irq_work_interrupt smp_irq_work_interrupt
1056 * Exception entry points.
1058 .macro zeroentry sym do_sym
1061 PARAVIRT_ADJUST_EXCEPTION_FRAME
1062 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1063 subq $ORIG_RAX-R15, %rsp
1064 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1067 movq %rsp,%rdi /* pt_regs pointer */
1068 xorl %esi,%esi /* no error code */
1070 jmp error_exit /* %ebx: no swapgs flag */
1075 .macro paranoidzeroentry sym do_sym
1078 PARAVIRT_ADJUST_EXCEPTION_FRAME
1079 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1080 subq $ORIG_RAX-R15, %rsp
1081 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1084 movq %rsp,%rdi /* pt_regs pointer */
1085 xorl %esi,%esi /* no error code */
1087 jmp paranoid_exit /* %ebx: no swapgs flag */
1092 #define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
1093 .macro paranoidzeroentry_ist sym do_sym ist
1096 PARAVIRT_ADJUST_EXCEPTION_FRAME
1097 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1098 subq $ORIG_RAX-R15, %rsp
1099 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1102 movq %rsp,%rdi /* pt_regs pointer */
1103 xorl %esi,%esi /* no error code */
1104 subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1106 addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
1107 jmp paranoid_exit /* %ebx: no swapgs flag */
1112 .macro errorentry sym do_sym
1115 PARAVIRT_ADJUST_EXCEPTION_FRAME
1116 subq $ORIG_RAX-R15, %rsp
1117 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1120 movq %rsp,%rdi /* pt_regs pointer */
1121 movq ORIG_RAX(%rsp),%rsi /* get error code */
1122 movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
1124 jmp error_exit /* %ebx: no swapgs flag */
1129 /* error code is on the stack already */
1130 .macro paranoiderrorentry sym do_sym
1133 PARAVIRT_ADJUST_EXCEPTION_FRAME
1134 subq $ORIG_RAX-R15, %rsp
1135 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1139 movq %rsp,%rdi /* pt_regs pointer */
1140 movq ORIG_RAX(%rsp),%rsi /* get error code */
1141 movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
1143 jmp paranoid_exit /* %ebx: no swapgs flag */
1148 zeroentry divide_error do_divide_error
1149 zeroentry overflow do_overflow
1150 zeroentry bounds do_bounds
1151 zeroentry invalid_op do_invalid_op
1152 zeroentry device_not_available do_device_not_available
1153 paranoiderrorentry double_fault do_double_fault
1154 zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun
1155 errorentry invalid_TSS do_invalid_TSS
1156 errorentry segment_not_present do_segment_not_present
1157 zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
1158 zeroentry coprocessor_error do_coprocessor_error
1159 errorentry alignment_check do_alignment_check
1160 zeroentry simd_coprocessor_error do_simd_coprocessor_error
1163 /* Reload gs selector with exception handling */
1164 /* edi: new selector */
1165 ENTRY(native_load_gs_index)
1168 DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
1172 2: mfence /* workaround */
1177 END(native_load_gs_index)
1179 _ASM_EXTABLE(gs_change,bad_gs)
1180 .section .fixup,"ax"
1181 /* running with kernelgs */
1183 SWAPGS /* switch back to user gs */
1189 ENTRY(kernel_thread_helper)
1190 pushq $0 # fake return address
1193 * Here we are in the child and the registers are set as they were
1194 * at kernel_thread() invocation in the parent.
1200 ud2 # padding for call trace
1202 END(kernel_thread_helper)
1205 * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
1207 * C extern interface:
1208 * extern long execve(const char *name, char **argv, char **envp)
1210 * asm input arguments:
1211 * rdi: name, rsi: argv, rdx: envp
1213 * We want to fallback into:
1214 * extern long sys_execve(const char *name, char **argv,char **envp, struct pt_regs *regs)
1216 * do_sys_execve asm fallback arguments:
1217 * rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
1219 ENTRY(kernel_execve)
1225 movq %rax, RAX(%rsp)
1228 je int_ret_from_sys_call
1235 /* Call softirq on interrupt stack. Interrupts are off. */
1239 CFI_REL_OFFSET rbp,0
1241 CFI_DEF_CFA_REGISTER rbp
1242 incl PER_CPU_VAR(irq_count)
1243 cmove PER_CPU_VAR(irq_stack_ptr),%rsp
1244 push %rbp # backlink for old unwinder
1248 CFI_DEF_CFA_REGISTER rsp
1249 CFI_ADJUST_CFA_OFFSET -8
1250 decl PER_CPU_VAR(irq_count)
1256 zeroentry xen_hypervisor_callback xen_do_hypervisor_callback
1259 * A note on the "critical region" in our callback handler.
1260 * We want to avoid stacking callback handlers due to events occurring
1261 * during handling of the last event. To do this, we keep events disabled
1262 * until we've done all processing. HOWEVER, we must enable events before
1263 * popping the stack frame (can't be done atomically) and so it would still
1264 * be possible to get enough handler activations to overflow the stack.
1265 * Although unlikely, bugs of that kind are hard to track down, so we'd
1266 * like to avoid the possibility.
1267 * So, on entry to the handler we detect whether we interrupted an
1268 * existing activation in its critical region -- if so, we pop the current
1269 * activation and restart the handler using the previous one.
1271 ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
1274 * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
1275 * see the correct pointer to the pt_regs
1277 movq %rdi, %rsp # we don't return, adjust the stack frame
1280 11: incl PER_CPU_VAR(irq_count)
1282 CFI_DEF_CFA_REGISTER rbp
1283 cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
1284 pushq %rbp # backlink for old unwinder
1285 call xen_evtchn_do_upcall
1287 CFI_DEF_CFA_REGISTER rsp
1288 decl PER_CPU_VAR(irq_count)
1291 END(xen_do_hypervisor_callback)
1294 * Hypervisor uses this for application faults while it executes.
1295 * We get here for two reasons:
1296 * 1. Fault while reloading DS, ES, FS or GS
1297 * 2. Fault while executing IRET
1298 * Category 1 we do not need to fix up as Xen has already reloaded all segment
1299 * registers that could be reloaded and zeroed the others.
1300 * Category 2 we fix up by killing the current process. We cannot use the
1301 * normal Linux return path in this case because if we use the IRET hypercall
1302 * to pop the stack frame we end up in an infinite loop of failsafe callbacks.
1303 * We distinguish between categories by comparing each saved segment register
1304 * with its current contents: any discrepancy means we in category 1.
1306 ENTRY(xen_failsafe_callback)
1308 /*CFI_REL_OFFSET gs,GS*/
1309 /*CFI_REL_OFFSET fs,FS*/
1310 /*CFI_REL_OFFSET es,ES*/
1311 /*CFI_REL_OFFSET ds,DS*/
1312 CFI_REL_OFFSET r11,8
1313 CFI_REL_OFFSET rcx,0
1327 /* All segments match their saved values => Category 2 (Bad IRET). */
1333 CFI_ADJUST_CFA_OFFSET -0x30
1334 pushq_cfi $0 /* RIP */
1337 jmp general_protection
1339 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
1345 CFI_ADJUST_CFA_OFFSET -0x30
1350 END(xen_failsafe_callback)
1352 apicinterrupt XEN_HVM_EVTCHN_CALLBACK \
1353 xen_hvm_callback_vector xen_evtchn_do_upcall
1355 #endif /* CONFIG_XEN */
1358 * Some functions should be protected against kprobes
1360 .pushsection .kprobes.text, "ax"
1362 paranoidzeroentry_ist debug do_debug DEBUG_STACK
1363 paranoidzeroentry_ist int3 do_int3 DEBUG_STACK
1364 paranoiderrorentry stack_segment do_stack_segment
1366 zeroentry xen_debug do_debug
1367 zeroentry xen_int3 do_int3
1368 errorentry xen_stack_segment do_stack_segment
1370 errorentry general_protection do_general_protection
1371 errorentry page_fault do_page_fault
1372 #ifdef CONFIG_KVM_GUEST
1373 errorentry async_page_fault do_async_page_fault
1375 #ifdef CONFIG_X86_MCE
1376 paranoidzeroentry machine_check *machine_check_vector(%rip)
1380 * "Paranoid" exit path from exception stack.
1381 * Paranoid because this is used by NMIs and cannot take
1382 * any kernel state for granted.
1383 * We don't do kernel preemption checks here, because only
1384 * NMI should be common and it does not enable IRQs and
1385 * cannot get reschedule ticks.
1387 * "trace" is 0 for the NMI handler only, because irq-tracing
1388 * is fundamentally NMI-unsafe. (we cannot change the soft and
1389 * hard flags at once, atomically)
1392 /* ebx: no swapgs flag */
1393 ENTRY(paranoid_exit)
1395 DISABLE_INTERRUPTS(CLBR_NONE)
1397 testl %ebx,%ebx /* swapgs needed? */
1398 jnz paranoid_restore
1400 jnz paranoid_userspace
1411 GET_THREAD_INFO(%rcx)
1412 movl TI_flags(%rcx),%ebx
1413 andl $_TIF_WORK_MASK,%ebx
1415 movq %rsp,%rdi /* &pt_regs */
1417 movq %rax,%rsp /* switch stack for scheduling */
1418 testl $_TIF_NEED_RESCHED,%ebx
1419 jnz paranoid_schedule
1420 movl %ebx,%edx /* arg3: thread flags */
1422 ENABLE_INTERRUPTS(CLBR_NONE)
1423 xorl %esi,%esi /* arg2: oldset */
1424 movq %rsp,%rdi /* arg1: &pt_regs */
1425 call do_notify_resume
1426 DISABLE_INTERRUPTS(CLBR_NONE)
1428 jmp paranoid_userspace
1431 ENABLE_INTERRUPTS(CLBR_ANY)
1433 DISABLE_INTERRUPTS(CLBR_ANY)
1435 jmp paranoid_userspace
1440 * Exception entry point. This expects an error code/orig_rax on the stack.
1441 * returns in "no swapgs flag" in %ebx.
1445 CFI_ADJUST_CFA_OFFSET 15*8
1446 /* oldrax contains error code */
1465 je error_kernelspace
1473 * There are two places in the kernel that can potentially fault with
1474 * usergs. Handle them here. The exception handlers after iret run with
1475 * kernel gs again, so don't set the user space flag. B stepping K8s
1476 * sometimes report an truncated RIP for IRET exceptions returning to
1477 * compat mode. Check for these here too.
1481 leaq irq_return(%rip),%rcx
1482 cmpq %rcx,RIP+8(%rsp)
1484 movl %ecx,%eax /* zero extend */
1485 cmpq %rax,RIP+8(%rsp)
1487 cmpq $gs_change,RIP+8(%rsp)
1492 /* Fix truncated RIP */
1493 movq %rcx,RIP+8(%rsp)
1499 /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
1504 DISABLE_INTERRUPTS(CLBR_NONE)
1506 GET_THREAD_INFO(%rcx)
1509 LOCKDEP_SYS_EXIT_IRQ
1510 movl TI_flags(%rcx),%edx
1511 movl $_TIF_WORK_MASK,%edi
1519 * Test if a given stack is an NMI stack or not.
1521 .macro test_in_nmi reg stack nmi_ret normal_ret
1524 subq $EXCEPTION_STKSZ, %\reg
1530 /* runs on exception stack */
1533 PARAVIRT_ADJUST_EXCEPTION_FRAME
1535 * We allow breakpoints in NMIs. If a breakpoint occurs, then
1536 * the iretq it performs will take us out of NMI context.
1537 * This means that we can have nested NMIs where the next
1538 * NMI is using the top of the stack of the previous NMI. We
1539 * can't let it execute because the nested NMI will corrupt the
1540 * stack of the previous NMI. NMI handlers are not re-entrant
1543 * To handle this case we do the following:
1544 * Check the a special location on the stack that contains
1545 * a variable that is set when NMIs are executing.
1546 * The interrupted task's stack is also checked to see if it
1548 * If the variable is not set and the stack is not the NMI
1550 * o Set the special variable on the stack
1551 * o Copy the interrupt frame into a "saved" location on the stack
1552 * o Copy the interrupt frame into a "copy" location on the stack
1553 * o Continue processing the NMI
1554 * If the variable is set or the previous stack is the NMI stack:
1555 * o Modify the "copy" location to jump to the repeate_nmi
1556 * o return back to the first NMI
1558 * Now on exit of the first NMI, we first clear the stack variable
1559 * The NMI stack will tell any nested NMIs at that point that it is
1560 * nested. Then we pop the stack normally with iret, and if there was
1561 * a nested NMI that updated the copy interrupt stack frame, a
1562 * jump will be made to the repeat_nmi code that will handle the second
1566 /* Use %rdx as out temp variable throughout */
1568 CFI_REL_OFFSET rdx, 0
1571 * If %cs was not the kernel segment, then the NMI triggered in user
1572 * space, which means it is definitely not nested.
1574 cmpl $__KERNEL_CS, 16(%rsp)
1578 * Check the special variable on the stack to see if NMIs are
1585 * Now test if the previous stack was an NMI stack.
1586 * We need the double check. We check the NMI stack to satisfy the
1587 * race when the first NMI clears the variable before returning.
1588 * We check the variable because the first NMI could be in a
1589 * breakpoint routine using a breakpoint stack.
1592 test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
1597 * Do nothing if we interrupted the fixup in repeat_nmi.
1598 * It's about to repeat the NMI handler, so we are fine
1599 * with ignoring this one.
1601 movq $repeat_nmi, %rdx
1604 movq $end_repeat_nmi, %rdx
1609 /* Set up the interrupted NMIs stack to jump to repeat_nmi */
1610 leaq -6*8(%rsp), %rdx
1612 CFI_ADJUST_CFA_OFFSET 6*8
1613 pushq_cfi $__KERNEL_DS
1616 pushq_cfi $__KERNEL_CS
1617 pushq_cfi $repeat_nmi
1619 /* Put stack back */
1621 CFI_ADJUST_CFA_OFFSET -11*8
1627 /* No need to check faults here */
1633 * Because nested NMIs will use the pushed location that we
1634 * stored in rdx, we must keep that space available.
1635 * Here's what our stack frame will look like:
1636 * +-------------------------+
1638 * | original Return RSP |
1639 * | original RFLAGS |
1642 * +-------------------------+
1643 * | temp storage for rdx |
1644 * +-------------------------+
1645 * | NMI executing variable |
1646 * +-------------------------+
1648 * | Saved Return RSP |
1652 * +-------------------------+
1654 * | copied Return RSP |
1658 * +-------------------------+
1660 * +-------------------------+
1662 * The saved stack frame is used to fix up the copied stack frame
1663 * that a nested NMI may change to make the interrupted NMI iret jump
1664 * to the repeat_nmi. The original stack frame and the temp storage
1665 * is also used by nested NMIs and can not be trusted on exit.
1667 /* Do not pop rdx, nested NMIs will corrupt that part of the stack */
1671 /* Set the NMI executing variable on the stack. */
1674 /* Copy the stack frame to the Saved frame */
1678 CFI_DEF_CFA_OFFSET SS+8-RIP
1680 /* Everything up to here is safe from nested NMIs */
1683 * If there was a nested NMI, the first NMI's iret will return
1684 * here. But NMIs are still enabled and we can take another
1685 * nested NMI. The nested NMI checks the interrupted RIP to see
1686 * if it is between repeat_nmi and end_repeat_nmi, and if so
1687 * it will just return, as we are about to repeat an NMI anyway.
1688 * This makes it safe to copy to the stack frame that a nested
1693 * Update the stack variable to say we are still in NMI (the update
1694 * is benign for the non-repeat case, where 1 was pushed just above
1695 * to this very stack slot).
1699 /* Make another copy, this one may be modified by nested NMIs */
1703 CFI_DEF_CFA_OFFSET SS+8-RIP
1707 * Everything below this point can be preempted by a nested
1708 * NMI if the first NMI took an exception and reset our iret stack
1709 * so that we repeat another NMI.
1711 pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
1712 subq $ORIG_RAX-R15, %rsp
1713 CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
1715 * Use save_paranoid to handle SWAPGS, but no need to use paranoid_exit
1716 * as we should not be calling schedule in NMI context.
1717 * Even with normal interrupts enabled. An NMI should not be
1718 * setting NEED_RESCHED or anything that normal interrupts and
1719 * exceptions might do.
1723 /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
1727 testl %ebx,%ebx /* swapgs needed? */
1733 /* Clear the NMI executing stack variable */
1739 ENTRY(ignore_sysret)
1747 * End of kprobes section