3 * Copyright (C) 1991, 1992 Linus Torvalds
7 * entry.S contains the system-call and fault low-level handling routines.
8 * This also contains the timer-interrupt handler, as well as all interrupts
9 * and faults that can result in a task-switch.
11 * NOTE: This code handles signal-recognition, which happens every time
12 * after a timer-interrupt and after each system call.
14 * I changed all the .align's to 4 (16 byte alignment), as that's faster
17 * Stack layout in 'syscall_exit':
18 * ptrace needs to have all regs on the stack.
19 * if the order here is changed, it needs to be
20 * updated in fork.c:copy_process, signal.c:do_signal,
21 * ptrace.c and ptrace.h
33 * 28(%esp) - %gs saved iff !CONFIG_X86_32_LAZY_GS
41 * "current" is in register %ebx during any slow entries.
44 #include <linux/linkage.h>
45 #include <asm/thread_info.h>
46 #include <asm/irqflags.h>
47 #include <asm/errno.h>
48 #include <asm/segment.h>
50 #include <asm/page_types.h>
51 #include <asm/percpu.h>
52 #include <asm/dwarf2.h>
53 #include <asm/processor-flags.h>
54 #include <asm/ftrace.h>
55 #include <asm/irq_vectors.h>
56 #include <asm/cpufeature.h>
57 #include <asm/alternative-asm.h>
59 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
60 #include <linux/elf-em.h>
61 #define AUDIT_ARCH_I386 (EM_386|__AUDIT_ARCH_LE)
62 #define __AUDIT_ARCH_LE 0x40000000
64 #ifndef CONFIG_AUDITSYSCALL
65 #define sysenter_audit syscall_trace_entry
66 #define sysexit_audit syscall_exit_work
69 .section .entry.text, "ax"
72 * We use macros for low-level operations which need to be overridden
73 * for paravirtualization. The following will never clobber any registers:
74 * INTERRUPT_RETURN (aka. "iret")
75 * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
76 * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
78 * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
79 * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
80 * Allowing a register to be clobbered can shrink the paravirt replacement
81 * enough to patch inline, increasing performance.
84 #define nr_syscalls ((syscall_table_size)/4)
87 #define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
89 #define preempt_stop(clobbers)
90 #define resume_kernel restore_all
93 .macro TRACE_IRQS_IRET
94 #ifdef CONFIG_TRACE_IRQFLAGS
95 testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off?
103 * User gs save/restore
105 * %gs is used for userland TLS and kernel only uses it for stack
106 * canary which is required to be at %gs:20 by gcc. Read the comment
107 * at the top of stackprotector.h for more info.
109 * Local labels 98 and 99 are used.
111 #ifdef CONFIG_X86_32_LAZY_GS
113 /* unfortunately push/pop can't be no-op */
118 addl $(4 + \pop), %esp
119 CFI_ADJUST_CFA_OFFSET -(4 + \pop)
124 /* all the rest are no-op */
131 .macro REG_TO_PTGS reg
133 .macro SET_KERNEL_GS reg
136 #else /* CONFIG_X86_32_LAZY_GS */
140 /*CFI_REL_OFFSET gs, 0*/
148 CFI_ADJUST_CFA_OFFSET -\pop
152 .pushsection .fixup, "ax"
155 .section __ex_table, "a"
162 98: mov PT_GS(%esp), %gs
165 .pushsection .fixup, "ax"
166 99: movl $0, PT_GS(%esp)
168 .section __ex_table, "a"
176 /*CFI_REGISTER gs, \reg*/
178 .macro REG_TO_PTGS reg
179 movl \reg, PT_GS(%esp)
180 /*CFI_REL_OFFSET gs, PT_GS*/
182 .macro SET_KERNEL_GS reg
183 movl $(__KERNEL_STACK_CANARY), \reg
187 #endif /* CONFIG_X86_32_LAZY_GS */
193 /*CFI_REL_OFFSET fs, 0;*/
195 /*CFI_REL_OFFSET es, 0;*/
197 /*CFI_REL_OFFSET ds, 0;*/
199 CFI_REL_OFFSET eax, 0
201 CFI_REL_OFFSET ebp, 0
203 CFI_REL_OFFSET edi, 0
205 CFI_REL_OFFSET esi, 0
207 CFI_REL_OFFSET edx, 0
209 CFI_REL_OFFSET ecx, 0
211 CFI_REL_OFFSET ebx, 0
212 movl $(__USER_DS), %edx
215 movl $(__KERNEL_PERCPU), %edx
220 .macro RESTORE_INT_REGS
237 .macro RESTORE_REGS pop=0
246 .pushsection .fixup, "ax"
253 .section __ex_table, "a"
262 .macro RING0_INT_FRAME
266 /*CFI_OFFSET cs, -2*4;*/
270 .macro RING0_EC_FRAME
274 /*CFI_OFFSET cs, -2*4;*/
278 .macro RING0_PTREGS_FRAME
281 CFI_DEF_CFA esp, PT_OLDESP-PT_EBX
282 /*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/
283 CFI_OFFSET eip, PT_EIP-PT_OLDESP
284 /*CFI_OFFSET es, PT_ES-PT_OLDESP;*/
285 /*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/
286 CFI_OFFSET eax, PT_EAX-PT_OLDESP
287 CFI_OFFSET ebp, PT_EBP-PT_OLDESP
288 CFI_OFFSET edi, PT_EDI-PT_OLDESP
289 CFI_OFFSET esi, PT_ESI-PT_OLDESP
290 CFI_OFFSET edx, PT_EDX-PT_OLDESP
291 CFI_OFFSET ecx, PT_ECX-PT_OLDESP
292 CFI_OFFSET ebx, PT_EBX-PT_OLDESP
299 GET_THREAD_INFO(%ebp)
301 pushl_cfi $0x0202 # Reset kernel eflags
308 * Interrupt exit functions should be protected against kprobes
310 .pushsection .kprobes.text, "ax"
312 * Return to user mode is not as complex as all this looks,
313 * but we want the default path for a system call return to
314 * go as quickly as possible which is why some of this is
315 * less clear than it otherwise should be.
318 # userspace resumption stub bypassing syscall exit tracing
322 preempt_stop(CLBR_ANY)
324 GET_THREAD_INFO(%ebp)
325 resume_userspace_sig:
327 movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS
328 movb PT_CS(%esp), %al
329 andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
332 * We can be coming here from a syscall done in the kernel space,
333 * e.g. a failed kernel_execve().
335 movl PT_CS(%esp), %eax
336 andl $SEGMENT_RPL_MASK, %eax
339 jb resume_kernel # not returning to v8086 or userspace
341 ENTRY(resume_userspace)
343 DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt
344 # setting need_resched or sigpending
345 # between sampling and the iret
347 movl TI_flags(%ebp), %ecx
348 andl $_TIF_WORK_MASK, %ecx # is there any work to be done on
349 # int/exception return?
352 END(ret_from_exception)
354 #ifdef CONFIG_PREEMPT
356 DISABLE_INTERRUPTS(CLBR_ANY)
357 cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ?
360 movl TI_flags(%ebp), %ecx # need_resched set ?
361 testb $_TIF_NEED_RESCHED, %cl
363 testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off (exception path) ?
365 call preempt_schedule_irq
371 * End of kprobes section
375 /* SYSENTER_RETURN points to after the "sysenter" instruction in
376 the vsyscall page. See vsyscall-sysentry.S, which defines the symbol. */
378 # sysenter call handler stub
379 ENTRY(ia32_sysenter_target)
383 CFI_REGISTER esp, ebp
384 movl TSS_sysenter_sp0(%esp),%esp
387 * Interrupts are disabled here, but we can't trace it until
388 * enough kernel state to call TRACE_IRQS_OFF can be called - but
389 * we immediately enable interrupts at that point anyway.
392 /*CFI_REL_OFFSET ss, 0*/
394 CFI_REL_OFFSET esp, 0
396 orl $X86_EFLAGS_IF, (%esp)
398 /*CFI_REL_OFFSET cs, 0*/
400 * Push current_thread_info()->sysenter_return to the stack.
401 * A tiny bit of offset fixup is necessary - 4*4 means the 4 words
402 * pushed above; +8 corresponds to copy_thread's esp0 setting.
404 pushl_cfi ((TI_sysenter_return)-THREAD_SIZE+8+4*4)(%esp)
405 CFI_REL_OFFSET eip, 0
409 ENABLE_INTERRUPTS(CLBR_NONE)
412 * Load the potential sixth argument from user stack.
413 * Careful about security.
415 cmpl $__PAGE_OFFSET-3,%ebp
418 movl %ebp,PT_EBP(%esp)
419 .section __ex_table,"a"
421 .long 1b,syscall_fault
424 GET_THREAD_INFO(%ebp)
426 testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
429 cmpl $(nr_syscalls), %eax
431 call *sys_call_table(,%eax,4)
432 movl %eax,PT_EAX(%esp)
435 DISABLE_INTERRUPTS(CLBR_ANY)
437 movl TI_flags(%ebp), %ecx
438 testl $_TIF_ALLWORK_MASK, %ecx
441 /* if something modifies registers it must also disable sysexit */
442 movl PT_EIP(%esp), %edx
443 movl PT_OLDESP(%esp), %ecx
446 1: mov PT_FS(%esp), %fs
448 ENABLE_INTERRUPTS_SYSEXIT
450 #ifdef CONFIG_AUDITSYSCALL
452 testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
453 jnz syscall_trace_entry
455 CFI_ADJUST_CFA_OFFSET -4
456 /* %esi already in 8(%esp) 6th arg: 4th syscall arg */
457 /* %edx already in 4(%esp) 5th arg: 3rd syscall arg */
458 /* %ecx already in 0(%esp) 4th arg: 2nd syscall arg */
459 movl %ebx,%ecx /* 3rd arg: 1st syscall arg */
460 movl %eax,%edx /* 2nd arg: syscall number */
461 movl $AUDIT_ARCH_I386,%eax /* 1st arg: audit arch */
462 call audit_syscall_entry
464 movl PT_EAX(%esp),%eax /* reload syscall number */
468 testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx
469 jne syscall_exit_work
471 ENABLE_INTERRUPTS(CLBR_ANY)
472 movl %eax,%edx /* second arg, syscall return value */
473 cmpl $0,%eax /* is it < 0? */
474 setl %al /* 1 if so, 0 if not */
475 movzbl %al,%eax /* zero-extend that */
476 inc %eax /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
477 call audit_syscall_exit
478 DISABLE_INTERRUPTS(CLBR_ANY)
480 movl TI_flags(%ebp), %ecx
481 testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx
482 jne syscall_exit_work
483 movl PT_EAX(%esp),%eax /* reload syscall return value */
488 .pushsection .fixup,"ax"
489 2: movl $0,PT_FS(%esp)
491 .section __ex_table,"a"
496 ENDPROC(ia32_sysenter_target)
499 * syscall stub including irq exit should be protected against kprobes
501 .pushsection .kprobes.text, "ax"
502 # system call handler stub
504 RING0_INT_FRAME # can't unwind into user space anyway
505 pushl_cfi %eax # save orig_eax
507 GET_THREAD_INFO(%ebp)
508 # system call tracing in operation / emulation
509 testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp)
510 jnz syscall_trace_entry
511 cmpl $(nr_syscalls), %eax
514 call *sys_call_table(,%eax,4)
515 movl %eax,PT_EAX(%esp) # store the return value
518 DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt
519 # setting need_resched or sigpending
520 # between sampling and the iret
522 movl TI_flags(%ebp), %ecx
523 testl $_TIF_ALLWORK_MASK, %ecx # current->work
524 jne syscall_exit_work
529 movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS
530 # Warning: PT_OLDSS(%esp) contains the wrong/random values if we
531 # are returning to the kernel.
532 # See comments in process.c:copy_thread() for details.
533 movb PT_OLDSS(%esp), %ah
534 movb PT_CS(%esp), %al
535 andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
536 cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax
538 je ldt_ss # returning to user-space with LDT SS
540 RESTORE_REGS 4 # skip orig_eax/error_code
545 pushl $0 # no error code
549 .section __ex_table,"a"
551 .long irq_return,iret_exc
556 larl PT_OLDSS(%esp), %eax
558 testl $0x00400000, %eax # returning to 32bit stack?
559 jnz restore_nocheck # allright, normal return
561 #ifdef CONFIG_PARAVIRT
563 * The kernel can't run on a non-flat stack if paravirt mode
564 * is active. Rather than try to fixup the high bits of
565 * ESP, bypass this code entirely. This may break DOSemu
566 * and/or Wine support in a paravirt VM, although the option
567 * is still available to implement the setting of the high
568 * 16-bits in the INTERRUPT_RETURN paravirt-op.
570 cmpl $0, pv_info+PARAVIRT_enabled
575 * Setup and switch to ESPFIX stack
577 * We're returning to userspace with a 16 bit stack. The CPU will not
578 * restore the high word of ESP for us on executing iret... This is an
579 * "official" bug of all the x86-compatible CPUs, which we can work
580 * around to make dosemu and wine happy. We do this by preloading the
581 * high word of ESP with the high word of the userspace ESP while
582 * compensating for the offset by changing to the ESPFIX segment with
583 * a base address that matches for the difference.
585 #define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8)
586 mov %esp, %edx /* load kernel esp */
587 mov PT_OLDESP(%esp), %eax /* load userspace esp */
588 mov %dx, %ax /* eax: new kernel esp */
589 sub %eax, %edx /* offset (low word is 0) */
591 mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */
592 mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */
593 pushl_cfi $__ESPFIX_SS
594 pushl_cfi %eax /* new kernel esp */
595 /* Disable interrupts, but do not irqtrace this section: we
596 * will soon execute iret and the tracer was already set to
597 * the irqstate after the iret */
598 DISABLE_INTERRUPTS(CLBR_EAX)
599 lss (%esp), %esp /* switch to espfix segment */
600 CFI_ADJUST_CFA_OFFSET -8
605 # perform work that needs to be done immediately before resumption
607 RING0_PTREGS_FRAME # can't unwind into user space anyway
609 testb $_TIF_NEED_RESCHED, %cl
614 DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt
615 # setting need_resched or sigpending
616 # between sampling and the iret
618 movl TI_flags(%ebp), %ecx
619 andl $_TIF_WORK_MASK, %ecx # is there any work to be done other
620 # than syscall tracing?
622 testb $_TIF_NEED_RESCHED, %cl
625 work_notifysig: # deal with pending signals and
626 # notify-resume requests
628 testl $X86_EFLAGS_VM, PT_EFLAGS(%esp)
630 jne work_notifysig_v86 # returning to kernel-space or
633 call do_notify_resume
634 jmp resume_userspace_sig
638 pushl_cfi %ecx # save ti_flags for do_notify_resume
639 call save_v86_state # %eax contains pt_regs pointer
646 call do_notify_resume
647 jmp resume_userspace_sig
650 # perform syscall exit tracing
653 movl $-ENOSYS,PT_EAX(%esp)
655 call syscall_trace_enter
656 /* What it returned is what we'll actually use. */
657 cmpl $(nr_syscalls), %eax
660 END(syscall_trace_entry)
662 # perform syscall exit tracing
665 testl $_TIF_WORK_SYSCALL_EXIT, %ecx
668 ENABLE_INTERRUPTS(CLBR_ANY) # could let syscall_trace_leave() call
671 call syscall_trace_leave
673 END(syscall_exit_work)
676 RING0_INT_FRAME # can't unwind into user space anyway
678 GET_THREAD_INFO(%ebp)
679 movl $-EFAULT,PT_EAX(%esp)
684 movl $-ENOSYS,PT_EAX(%esp)
689 movl $-ENOSYS,PT_EAX(%esp)
690 jmp sysenter_after_call
694 * End of kprobes section
699 * System calls that need a pt_regs pointer.
701 #define PTREGSCALL0(name) \
707 #define PTREGSCALL1(name) \
711 movl (PT_EBX+4)(%esp),%eax; \
714 #define PTREGSCALL2(name) \
718 movl (PT_ECX+4)(%esp),%edx; \
719 movl (PT_EBX+4)(%esp),%eax; \
722 #define PTREGSCALL3(name) \
728 movl PT_EDX(%eax),%ecx; \
729 movl PT_ECX(%eax),%edx; \
730 movl PT_EBX(%eax),%eax; \
733 CFI_ADJUST_CFA_OFFSET -4; \
736 ENDPROC(ptregs_##name)
742 PTREGSCALL2(sigaltstack)
743 PTREGSCALL0(sigreturn)
744 PTREGSCALL0(rt_sigreturn)
748 /* Clone is an oddball. The 4th arg is in %edi */
754 pushl_cfi PT_EDI(%eax)
755 movl PT_EDX(%eax),%ecx
756 movl PT_ECX(%eax),%edx
757 movl PT_EBX(%eax),%eax
760 CFI_ADJUST_CFA_OFFSET -8
763 ENDPROC(ptregs_clone)
765 .macro FIXUP_ESPFIX_STACK
767 * Switch back for ESPFIX stack to the normal zerobased stack
769 * We can't call C functions using the ESPFIX stack. This code reads
770 * the high word of the segment base from the GDT and swiches to the
771 * normal stack and adjusts ESP with the matching offset.
773 /* fixup the stack */
774 mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */
775 mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */
777 addl %esp, %eax /* the adjusted stack pointer */
778 pushl_cfi $__KERNEL_DS
780 lss (%esp), %esp /* switch to the normal stack segment */
781 CFI_ADJUST_CFA_OFFSET -8
783 .macro UNWIND_ESPFIX_STACK
785 /* see if on espfix stack */
786 cmpw $__ESPFIX_SS, %ax
788 movl $__KERNEL_DS, %eax
791 /* switch to normal stack */
797 * Build the entry stubs and pointer table with some assembler magic.
798 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
799 * single cache line on all modern x86 implementations.
801 .section .init.rodata,"a"
803 .section .entry.text, "ax"
805 .p2align CONFIG_X86_L1_CACHE_SHIFT
806 ENTRY(irq_entries_start)
808 vector=FIRST_EXTERNAL_VECTOR
809 .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7
812 .if vector < NR_VECTORS
813 .if vector <> FIRST_EXTERNAL_VECTOR
814 CFI_ADJUST_CFA_OFFSET -4
816 1: pushl_cfi $(~vector+0x80) /* Note: always in signed byte range */
817 .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6
822 .section .entry.text, "ax"
826 2: jmp common_interrupt
828 END(irq_entries_start)
835 * the CPU automatically disables interrupts when executing an IRQ vector,
836 * so IRQ-flags tracing has to follow that:
838 .p2align CONFIG_X86_L1_CACHE_SHIFT
840 addl $-0x80,(%esp) /* Adjust vector into the [-256,-1] range */
846 ENDPROC(common_interrupt)
850 * Irq entries should be protected against kprobes
852 .pushsection .kprobes.text, "ax"
853 #define BUILD_INTERRUPT3(name, nr, fn) \
865 #define BUILD_INTERRUPT(name, nr) BUILD_INTERRUPT3(name, nr, smp_##name)
867 /* The include is where all of the SMP etc. interrupts come from */
868 #include <asm/entry_arch.h>
870 ENTRY(coprocessor_error)
873 pushl_cfi $do_coprocessor_error
876 END(coprocessor_error)
878 ENTRY(simd_coprocessor_error)
881 #ifdef CONFIG_X86_INVD_BUG
882 /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
883 661: pushl_cfi $do_general_protection
885 .section .altinstructions,"a"
886 altinstruction_entry 661b, 663f, X86_FEATURE_XMM, 662b-661b, 664f-663f
888 .section .altinstr_replacement,"ax"
889 663: pushl $do_simd_coprocessor_error
893 pushl_cfi $do_simd_coprocessor_error
897 END(simd_coprocessor_error)
899 ENTRY(device_not_available)
901 pushl_cfi $-1 # mark this as an int
902 pushl_cfi $do_device_not_available
905 END(device_not_available)
907 #ifdef CONFIG_PARAVIRT
910 .section __ex_table,"a"
912 .long native_iret, iret_exc
916 ENTRY(native_irq_enable_sysexit)
919 END(native_irq_enable_sysexit)
925 pushl_cfi $do_overflow
941 pushl_cfi $do_invalid_op
946 ENTRY(coprocessor_segment_overrun)
949 pushl_cfi $do_coprocessor_segment_overrun
952 END(coprocessor_segment_overrun)
956 pushl_cfi $do_invalid_TSS
961 ENTRY(segment_not_present)
963 pushl_cfi $do_segment_not_present
966 END(segment_not_present)
970 pushl_cfi $do_stack_segment
975 ENTRY(alignment_check)
977 pushl_cfi $do_alignment_check
984 pushl_cfi $0 # no error code
985 pushl_cfi $do_divide_error
990 #ifdef CONFIG_X86_MCE
994 pushl_cfi machine_check_vector
1000 ENTRY(spurious_interrupt_bug)
1003 pushl_cfi $do_spurious_interrupt_bug
1006 END(spurious_interrupt_bug)
1008 * End of kprobes section
1012 ENTRY(kernel_thread_helper)
1013 pushl $0 # fake return address for unwinder
1018 ud2 # padding for call trace
1020 ENDPROC(kernel_thread_helper)
1023 /* Xen doesn't set %esp to be precisely what the normal sysenter
1024 entrypoint expects, so fix it up before using the normal path. */
1025 ENTRY(xen_sysenter_target)
1027 addl $5*4, %esp /* remove xen-provided frame */
1028 CFI_ADJUST_CFA_OFFSET -5*4
1029 jmp sysenter_past_esp
1032 ENTRY(xen_hypervisor_callback)
1034 pushl_cfi $-1 /* orig_ax = -1 => not a system call */
1038 /* Check to see if we got the event in the critical
1039 region in xen_iret_direct, after we've reenabled
1040 events and checked for pending events. This simulates
1041 iret instruction's behaviour where it delivers a
1042 pending interrupt when enabling interrupts. */
1043 movl PT_EIP(%esp),%eax
1044 cmpl $xen_iret_start_crit,%eax
1046 cmpl $xen_iret_end_crit,%eax
1049 jmp xen_iret_crit_fixup
1051 ENTRY(xen_do_upcall)
1053 call xen_evtchn_do_upcall
1056 ENDPROC(xen_hypervisor_callback)
1058 # Hypervisor uses this for application faults while it executes.
1059 # We get here for two reasons:
1060 # 1. Fault while reloading DS, ES, FS or GS
1061 # 2. Fault while executing IRET
1062 # Category 1 we fix up by reattempting the load, and zeroing the segment
1063 # register if the load fails.
1064 # Category 2 we fix up by jumping to do_iret_error. We cannot use the
1065 # normal Linux return path in this case because if we use the IRET hypercall
1066 # to pop the stack frame we end up in an infinite loop of failsafe callbacks.
1067 # We distinguish between categories by maintaining a status value in EAX.
1068 ENTRY(xen_failsafe_callback)
1076 /* EAX == 0 => Category 1 (Bad segment)
1077 EAX != 0 => Category 2 (Bad IRET) */
1081 CFI_ADJUST_CFA_OFFSET -16
1084 5: pushl_cfi $-1 /* orig_ax = -1 => not a system call */
1086 jmp ret_from_exception
1089 .section .fixup,"ax"
1103 .section __ex_table,"a"
1110 ENDPROC(xen_failsafe_callback)
1112 BUILD_INTERRUPT3(xen_hvm_callback_vector, XEN_HVM_EVTCHN_CALLBACK,
1113 xen_evtchn_do_upcall)
1115 #endif /* CONFIG_XEN */
1117 #ifdef CONFIG_FUNCTION_TRACER
1118 #ifdef CONFIG_DYNAMIC_FTRACE
1124 ENTRY(ftrace_caller)
1125 cmpl $0, function_trace_stop
1131 movl 0xc(%esp), %eax
1132 movl 0x4(%ebp), %edx
1133 subl $MCOUNT_INSN_SIZE, %eax
1142 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1143 .globl ftrace_graph_call
1153 #else /* ! CONFIG_DYNAMIC_FTRACE */
1156 cmpl $0, function_trace_stop
1159 cmpl $ftrace_stub, ftrace_trace_function
1161 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1162 cmpl $ftrace_stub, ftrace_graph_return
1163 jnz ftrace_graph_caller
1165 cmpl $ftrace_graph_entry_stub, ftrace_graph_entry
1166 jnz ftrace_graph_caller
1172 /* taken from glibc */
1177 movl 0xc(%esp), %eax
1178 movl 0x4(%ebp), %edx
1179 subl $MCOUNT_INSN_SIZE, %eax
1181 call *ftrace_trace_function
1188 #endif /* CONFIG_DYNAMIC_FTRACE */
1189 #endif /* CONFIG_FUNCTION_TRACER */
1191 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1192 ENTRY(ftrace_graph_caller)
1193 cmpl $0, function_trace_stop
1199 movl 0xc(%esp), %edx
1202 subl $MCOUNT_INSN_SIZE, %edx
1203 call prepare_ftrace_return
1208 END(ftrace_graph_caller)
1210 .globl return_to_handler
1215 call ftrace_return_to_handler
1222 .section .rodata,"a"
1223 #include "syscall_table_32.S"
1225 syscall_table_size=(.-sys_call_table)
1228 * Some functions should be protected against kprobes
1230 .pushsection .kprobes.text, "ax"
1234 pushl_cfi $do_page_fault
1237 /* the function address is in %gs's slot on the stack */
1239 /*CFI_REL_OFFSET fs, 0*/
1241 /*CFI_REL_OFFSET es, 0*/
1243 /*CFI_REL_OFFSET ds, 0*/
1245 CFI_REL_OFFSET eax, 0
1247 CFI_REL_OFFSET ebp, 0
1249 CFI_REL_OFFSET edi, 0
1251 CFI_REL_OFFSET esi, 0
1253 CFI_REL_OFFSET edx, 0
1255 CFI_REL_OFFSET ecx, 0
1257 CFI_REL_OFFSET ebx, 0
1259 movl $(__KERNEL_PERCPU), %ecx
1263 movl PT_GS(%esp), %edi # get the function address
1264 movl PT_ORIG_EAX(%esp), %edx # get the error code
1265 movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart
1268 movl $(__USER_DS), %ecx
1272 movl %esp,%eax # pt_regs pointer
1274 jmp ret_from_exception
1279 * Debug traps and NMI can happen at the one SYSENTER instruction
1280 * that sets up the real kernel stack. Check here, since we can't
1281 * allow the wrong stack to be used.
1283 * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have
1284 * already pushed 3 words if it hits on the sysenter instruction:
1285 * eflags, cs and eip.
1287 * We just load the right stack, and push the three (known) values
1288 * by hand onto the new stack - while updating the return eip past
1289 * the instruction that would have done it for sysenter.
1291 .macro FIX_STACK offset ok label
1292 cmpw $__KERNEL_CS, 4(%esp)
1295 movl TSS_sysenter_sp0 + \offset(%esp), %esp
1299 pushl_cfi $__KERNEL_CS
1300 pushl_cfi $sysenter_past_esp
1301 CFI_REL_OFFSET eip, 0
1306 cmpl $ia32_sysenter_target,(%esp)
1307 jne debug_stack_correct
1308 FIX_STACK 12, debug_stack_correct, debug_esp_fix_insn
1309 debug_stack_correct:
1310 pushl_cfi $-1 # mark this as an int
1313 xorl %edx,%edx # error code 0
1314 movl %esp,%eax # pt_regs pointer
1316 jmp ret_from_exception
1321 * NMI is doubly nasty. It can happen _while_ we're handling
1322 * a debug fault, and the debug fault hasn't yet been able to
1323 * clear up the stack. So we first check whether we got an
1324 * NMI on the sysenter entry path, but after that we need to
1325 * check whether we got an NMI on the debug path where the debug
1326 * fault happened on the sysenter path.
1332 cmpw $__ESPFIX_SS, %ax
1335 cmpl $ia32_sysenter_target,(%esp)
1339 /* Do not access memory above the end of our stack page,
1340 * it might not exist.
1342 andl $(THREAD_SIZE-1),%eax
1343 cmpl $(THREAD_SIZE-20),%eax
1345 jae nmi_stack_correct
1346 cmpl $ia32_sysenter_target,12(%esp)
1347 je nmi_debug_stack_check
1349 /* We have a RING0_INT_FRAME here */
1352 xorl %edx,%edx # zero error code
1353 movl %esp,%eax # pt_regs pointer
1355 jmp restore_all_notrace
1360 FIX_STACK 12, nmi_stack_correct, 1
1361 jmp nmi_stack_correct
1363 nmi_debug_stack_check:
1364 /* We have a RING0_INT_FRAME here */
1365 cmpw $__KERNEL_CS,16(%esp)
1366 jne nmi_stack_correct
1368 jb nmi_stack_correct
1369 cmpl $debug_esp_fix_insn,(%esp)
1370 ja nmi_stack_correct
1371 FIX_STACK 24, nmi_stack_correct, 1
1372 jmp nmi_stack_correct
1375 /* We have a RING0_INT_FRAME here.
1377 * create the pointer to lss back
1382 /* copy the iret frame of 12 bytes */
1388 FIXUP_ESPFIX_STACK # %eax == %esp
1389 xorl %edx,%edx # zero error code
1392 lss 12+4(%esp), %esp # back to espfix stack
1393 CFI_ADJUST_CFA_OFFSET -24
1400 pushl_cfi $-1 # mark this as an int
1403 xorl %edx,%edx # zero error code
1404 movl %esp,%eax # pt_regs pointer
1406 jmp ret_from_exception
1410 ENTRY(general_protection)
1412 pushl_cfi $do_general_protection
1415 END(general_protection)
1417 #ifdef CONFIG_KVM_GUEST
1418 ENTRY(async_page_fault)
1420 pushl_cfi $do_async_page_fault
1423 END(async_page_fault)
1427 * End of kprobes section