/* * * Copyright (C) 1991, 1992 Linus Torvalds */ /* * entry.S contains the system-call and fault low-level handling routines. * This also contains the timer-interrupt handler, as well as all interrupts * and faults that can result in a task-switch. * * NOTE: This code handles signal-recognition, which happens every time * after a timer-interrupt and after each system call. * * I changed all the .align's to 4 (16 byte alignment), as that's faster * on a 486. * * Stack layout in 'syscall_exit': * ptrace needs to have all regs on the stack. * if the order here is changed, it needs to be * updated in fork.c:copy_process, signal.c:do_signal, * ptrace.c and ptrace.h * * 0(%esp) - %ebx * 4(%esp) - %ecx * 8(%esp) - %edx * C(%esp) - %esi * 10(%esp) - %edi * 14(%esp) - %ebp * 18(%esp) - %eax * 1C(%esp) - %ds * 20(%esp) - %es * 24(%esp) - %fs * 28(%esp) - %gs saved iff !CONFIG_X86_32_LAZY_GS * 2C(%esp) - orig_eax * 30(%esp) - %eip * 34(%esp) - %cs * 38(%esp) - %eflags * 3C(%esp) - %oldesp * 40(%esp) - %oldss * * "current" is in register %ebx during any slow entries. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* Avoid __ASSEMBLER__'ifying just for this. */ #include #define AUDIT_ARCH_I386 (EM_386|__AUDIT_ARCH_LE) #define __AUDIT_ARCH_LE 0x40000000 #ifndef CONFIG_AUDITSYSCALL #define sysenter_audit syscall_trace_entry #define sysexit_audit syscall_exit_work #endif .section .entry.text, "ax" /* * We use macros for low-level operations which need to be overridden * for paravirtualization. The following will never clobber any registers: * INTERRUPT_RETURN (aka. "iret") * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax") * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit"). * * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY). * Allowing a register to be clobbered can shrink the paravirt replacement * enough to patch inline, increasing performance. */ #ifdef CONFIG_PREEMPT #define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF #else #define preempt_stop(clobbers) #define resume_kernel restore_all #endif .macro TRACE_IRQS_IRET #ifdef CONFIG_TRACE_IRQFLAGS testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off? jz 1f TRACE_IRQS_ON 1: #endif .endm /* * User gs save/restore * * %gs is used for userland TLS and kernel only uses it for stack * canary which is required to be at %gs:20 by gcc. Read the comment * at the top of stackprotector.h for more info. * * Local labels 98 and 99 are used. */ #ifdef CONFIG_X86_32_LAZY_GS /* unfortunately push/pop can't be no-op */ .macro PUSH_GS pushl_cfi $0 .endm .macro POP_GS pop=0 addl $(4 + \pop), %esp CFI_ADJUST_CFA_OFFSET -(4 + \pop) .endm .macro POP_GS_EX .endm /* all the rest are no-op */ .macro PTGS_TO_GS .endm .macro PTGS_TO_GS_EX .endm .macro GS_TO_REG reg .endm .macro REG_TO_PTGS reg .endm .macro SET_KERNEL_GS reg .endm #else /* CONFIG_X86_32_LAZY_GS */ .macro PUSH_GS pushl_cfi %gs /*CFI_REL_OFFSET gs, 0*/ .endm .macro POP_GS pop=0 98: popl_cfi %gs /*CFI_RESTORE gs*/ .if \pop <> 0 add $\pop, %esp CFI_ADJUST_CFA_OFFSET -\pop .endif .endm .macro POP_GS_EX .pushsection .fixup, "ax" 99: movl $0, (%esp) jmp 98b .popsection _ASM_EXTABLE(98b,99b) .endm .macro PTGS_TO_GS 98: mov PT_GS(%esp), %gs .endm .macro PTGS_TO_GS_EX .pushsection .fixup, "ax" 99: movl $0, PT_GS(%esp) jmp 98b .popsection _ASM_EXTABLE(98b,99b) .endm .macro GS_TO_REG reg movl %gs, \reg /*CFI_REGISTER gs, \reg*/ .endm .macro REG_TO_PTGS reg movl \reg, PT_GS(%esp) /*CFI_REL_OFFSET gs, PT_GS*/ .endm .macro SET_KERNEL_GS reg movl $(__KERNEL_STACK_CANARY), \reg movl \reg, %gs .endm #endif /* CONFIG_X86_32_LAZY_GS */ .macro SAVE_ALL cld PUSH_GS pushl_cfi %fs /*CFI_REL_OFFSET fs, 0;*/ pushl_cfi %es /*CFI_REL_OFFSET es, 0;*/ pushl_cfi %ds /*CFI_REL_OFFSET ds, 0;*/ pushl_cfi %eax CFI_REL_OFFSET eax, 0 pushl_cfi %ebp CFI_REL_OFFSET ebp, 0 pushl_cfi %edi CFI_REL_OFFSET edi, 0 pushl_cfi %esi CFI_REL_OFFSET esi, 0 pushl_cfi %edx CFI_REL_OFFSET edx, 0 pushl_cfi %ecx CFI_REL_OFFSET ecx, 0 pushl_cfi %ebx CFI_REL_OFFSET ebx, 0 movl $(__USER_DS), %edx movl %edx, %ds movl %edx, %es movl $(__KERNEL_PERCPU), %edx movl %edx, %fs SET_KERNEL_GS %edx .endm .macro RESTORE_INT_REGS popl_cfi %ebx CFI_RESTORE ebx popl_cfi %ecx CFI_RESTORE ecx popl_cfi %edx CFI_RESTORE edx popl_cfi %esi CFI_RESTORE esi popl_cfi %edi CFI_RESTORE edi popl_cfi %ebp CFI_RESTORE ebp popl_cfi %eax CFI_RESTORE eax .endm .macro RESTORE_REGS pop=0 RESTORE_INT_REGS 1: popl_cfi %ds /*CFI_RESTORE ds;*/ 2: popl_cfi %es /*CFI_RESTORE es;*/ 3: popl_cfi %fs /*CFI_RESTORE fs;*/ POP_GS \pop .pushsection .fixup, "ax" 4: movl $0, (%esp) jmp 1b 5: movl $0, (%esp) jmp 2b 6: movl $0, (%esp) jmp 3b .popsection _ASM_EXTABLE(1b,4b) _ASM_EXTABLE(2b,5b) _ASM_EXTABLE(3b,6b) POP_GS_EX .endm .macro RING0_INT_FRAME CFI_STARTPROC simple CFI_SIGNAL_FRAME CFI_DEF_CFA esp, 3*4 /*CFI_OFFSET cs, -2*4;*/ CFI_OFFSET eip, -3*4 .endm .macro RING0_EC_FRAME CFI_STARTPROC simple CFI_SIGNAL_FRAME CFI_DEF_CFA esp, 4*4 /*CFI_OFFSET cs, -2*4;*/ CFI_OFFSET eip, -3*4 .endm .macro RING0_PTREGS_FRAME CFI_STARTPROC simple CFI_SIGNAL_FRAME CFI_DEF_CFA esp, PT_OLDESP-PT_EBX /*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/ CFI_OFFSET eip, PT_EIP-PT_OLDESP /*CFI_OFFSET es, PT_ES-PT_OLDESP;*/ /*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/ CFI_OFFSET eax, PT_EAX-PT_OLDESP CFI_OFFSET ebp, PT_EBP-PT_OLDESP CFI_OFFSET edi, PT_EDI-PT_OLDESP CFI_OFFSET esi, PT_ESI-PT_OLDESP CFI_OFFSET edx, PT_EDX-PT_OLDESP CFI_OFFSET ecx, PT_ECX-PT_OLDESP CFI_OFFSET ebx, PT_EBX-PT_OLDESP .endm ENTRY(ret_from_fork) CFI_STARTPROC pushl_cfi %eax call schedule_tail GET_THREAD_INFO(%ebp) popl_cfi %eax pushl_cfi $0x0202 # Reset kernel eflags popfl_cfi jmp syscall_exit CFI_ENDPROC END(ret_from_fork) ENTRY(ret_from_kernel_execve) movl %eax, %esp movl $0,PT_EAX(%esp) GET_THREAD_INFO(%ebp) jmp syscall_exit END(ret_from_kernel_execve) /* * Interrupt exit functions should be protected against kprobes */ .pushsection .kprobes.text, "ax" /* * Return to user mode is not as complex as all this looks, * but we want the default path for a system call return to * go as quickly as possible which is why some of this is * less clear than it otherwise should be. */ # userspace resumption stub bypassing syscall exit tracing ALIGN RING0_PTREGS_FRAME ret_from_exception: preempt_stop(CLBR_ANY) ret_from_intr: GET_THREAD_INFO(%ebp) #ifdef CONFIG_VM86 movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS movb PT_CS(%esp), %al andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax #else /* * We can be coming here from child spawned by kernel_thread(). */ movl PT_CS(%esp), %eax andl $SEGMENT_RPL_MASK, %eax #endif cmpl $USER_RPL, %eax jb resume_kernel # not returning to v8086 or userspace ENTRY(resume_userspace) LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt # setting need_resched or sigpending # between sampling and the iret TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx andl $_TIF_WORK_MASK, %ecx # is there any work to be done on # int/exception return? jne work_pending jmp restore_all END(ret_from_exception) #ifdef CONFIG_PREEMPT ENTRY(resume_kernel) DISABLE_INTERRUPTS(CLBR_ANY) cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ? jnz restore_all need_resched: movl TI_flags(%ebp), %ecx # need_resched set ? testb $_TIF_NEED_RESCHED, %cl jz restore_all testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off (exception path) ? jz restore_all call preempt_schedule_irq jmp need_resched END(resume_kernel) #endif CFI_ENDPROC /* * End of kprobes section */ .popsection /* SYSENTER_RETURN points to after the "sysenter" instruction in the vsyscall page. See vsyscall-sysentry.S, which defines the symbol. */ # sysenter call handler stub ENTRY(ia32_sysenter_target) CFI_STARTPROC simple CFI_SIGNAL_FRAME CFI_DEF_CFA esp, 0 CFI_REGISTER esp, ebp movl TSS_sysenter_sp0(%esp),%esp sysenter_past_esp: /* * Interrupts are disabled here, but we can't trace it until * enough kernel state to call TRACE_IRQS_OFF can be called - but * we immediately enable interrupts at that point anyway. */ pushl_cfi $__USER_DS /*CFI_REL_OFFSET ss, 0*/ pushl_cfi %ebp CFI_REL_OFFSET esp, 0 pushfl_cfi orl $X86_EFLAGS_IF, (%esp) pushl_cfi $__USER_CS /*CFI_REL_OFFSET cs, 0*/ /* * Push current_thread_info()->sysenter_return to the stack. * A tiny bit of offset fixup is necessary - 4*4 means the 4 words * pushed above; +8 corresponds to copy_thread's esp0 setting. */ pushl_cfi ((TI_sysenter_return)-THREAD_SIZE+8+4*4)(%esp) CFI_REL_OFFSET eip, 0 pushl_cfi %eax SAVE_ALL ENABLE_INTERRUPTS(CLBR_NONE) /* * Load the potential sixth argument from user stack. * Careful about security. */ cmpl $__PAGE_OFFSET-3,%ebp jae syscall_fault ASM_STAC 1: movl (%ebp),%ebp ASM_CLAC movl %ebp,PT_EBP(%esp) _ASM_EXTABLE(1b,syscall_fault) GET_THREAD_INFO(%ebp) testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp) jnz sysenter_audit sysenter_do_call: cmpl $(NR_syscalls), %eax jae syscall_badsys call *sys_call_table(,%eax,4) movl %eax,PT_EAX(%esp) LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx testl $_TIF_ALLWORK_MASK, %ecx jne sysexit_audit sysenter_exit: /* if something modifies registers it must also disable sysexit */ movl PT_EIP(%esp), %edx movl PT_OLDESP(%esp), %ecx xorl %ebp,%ebp TRACE_IRQS_ON 1: mov PT_FS(%esp), %fs PTGS_TO_GS ENABLE_INTERRUPTS_SYSEXIT #ifdef CONFIG_AUDITSYSCALL sysenter_audit: testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp) jnz syscall_trace_entry addl $4,%esp CFI_ADJUST_CFA_OFFSET -4 /* %esi already in 8(%esp) 6th arg: 4th syscall arg */ /* %edx already in 4(%esp) 5th arg: 3rd syscall arg */ /* %ecx already in 0(%esp) 4th arg: 2nd syscall arg */ movl %ebx,%ecx /* 3rd arg: 1st syscall arg */ movl %eax,%edx /* 2nd arg: syscall number */ movl $AUDIT_ARCH_I386,%eax /* 1st arg: audit arch */ call __audit_syscall_entry pushl_cfi %ebx movl PT_EAX(%esp),%eax /* reload syscall number */ jmp sysenter_do_call sysexit_audit: testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx jne syscall_exit_work TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_ANY) movl %eax,%edx /* second arg, syscall return value */ cmpl $-MAX_ERRNO,%eax /* is it an error ? */ setbe %al /* 1 if so, 0 if not */ movzbl %al,%eax /* zero-extend that */ call __audit_syscall_exit DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx jne syscall_exit_work movl PT_EAX(%esp),%eax /* reload syscall return value */ jmp sysenter_exit #endif CFI_ENDPROC .pushsection .fixup,"ax" 2: movl $0,PT_FS(%esp) jmp 1b .popsection _ASM_EXTABLE(1b,2b) PTGS_TO_GS_EX ENDPROC(ia32_sysenter_target) /* * syscall stub including irq exit should be protected against kprobes */ .pushsection .kprobes.text, "ax" # system call handler stub ENTRY(system_call) RING0_INT_FRAME # can't unwind into user space anyway ASM_CLAC pushl_cfi %eax # save orig_eax SAVE_ALL GET_THREAD_INFO(%ebp) # system call tracing in operation / emulation testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp) jnz syscall_trace_entry cmpl $(NR_syscalls), %eax jae syscall_badsys syscall_call: call *sys_call_table(,%eax,4) movl %eax,PT_EAX(%esp) # store the return value syscall_exit: LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt # setting need_resched or sigpending # between sampling and the iret TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx testl $_TIF_ALLWORK_MASK, %ecx # current->work jne syscall_exit_work restore_all: TRACE_IRQS_IRET restore_all_notrace: movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS # Warning: PT_OLDSS(%esp) contains the wrong/random values if we # are returning to the kernel. # See comments in process.c:copy_thread() for details. movb PT_OLDSS(%esp), %ah movb PT_CS(%esp), %al andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax CFI_REMEMBER_STATE je ldt_ss # returning to user-space with LDT SS restore_nocheck: RESTORE_REGS 4 # skip orig_eax/error_code irq_return: INTERRUPT_RETURN .section .fixup,"ax" ENTRY(iret_exc) pushl $0 # no error code pushl $do_iret_error jmp error_code .previous _ASM_EXTABLE(irq_return,iret_exc) CFI_RESTORE_STATE ldt_ss: larl PT_OLDSS(%esp), %eax jnz restore_nocheck testl $0x00400000, %eax # returning to 32bit stack? jnz restore_nocheck # allright, normal return #ifdef CONFIG_PARAVIRT /* * The kernel can't run on a non-flat stack if paravirt mode * is active. Rather than try to fixup the high bits of * ESP, bypass this code entirely. This may break DOSemu * and/or Wine support in a paravirt VM, although the option * is still available to implement the setting of the high * 16-bits in the INTERRUPT_RETURN paravirt-op. */ cmpl $0, pv_info+PARAVIRT_enabled jne restore_nocheck #endif /* * Setup and switch to ESPFIX stack * * We're returning to userspace with a 16 bit stack. The CPU will not * restore the high word of ESP for us on executing iret... This is an * "official" bug of all the x86-compatible CPUs, which we can work * around to make dosemu and wine happy. We do this by preloading the * high word of ESP with the high word of the userspace ESP while * compensating for the offset by changing to the ESPFIX segment with * a base address that matches for the difference. */ #define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8) mov %esp, %edx /* load kernel esp */ mov PT_OLDESP(%esp), %eax /* load userspace esp */ mov %dx, %ax /* eax: new kernel esp */ sub %eax, %edx /* offset (low word is 0) */ shr $16, %edx mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */ mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */ pushl_cfi $__ESPFIX_SS pushl_cfi %eax /* new kernel esp */ /* Disable interrupts, but do not irqtrace this section: we * will soon execute iret and the tracer was already set to * the irqstate after the iret */ DISABLE_INTERRUPTS(CLBR_EAX) lss (%esp), %esp /* switch to espfix segment */ CFI_ADJUST_CFA_OFFSET -8 jmp restore_nocheck CFI_ENDPROC ENDPROC(system_call) # perform work that needs to be done immediately before resumption ALIGN RING0_PTREGS_FRAME # can't unwind into user space anyway work_pending: testb $_TIF_NEED_RESCHED, %cl jz work_notifysig work_resched: call schedule LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt # setting need_resched or sigpending # between sampling and the iret TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx andl $_TIF_WORK_MASK, %ecx # is there any work to be done other # than syscall tracing? jz restore_all testb $_TIF_NEED_RESCHED, %cl jnz work_resched work_notifysig: # deal with pending signals and # notify-resume requests #ifdef CONFIG_VM86 testl $X86_EFLAGS_VM, PT_EFLAGS(%esp) movl %esp, %eax jne work_notifysig_v86 # returning to kernel-space or # vm86-space 1: #else movl %esp, %eax #endif TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) movb PT_CS(%esp), %bl andb $SEGMENT_RPL_MASK, %bl cmpb $USER_RPL, %bl jb resume_kernel xorl %edx, %edx call do_notify_resume jmp resume_userspace #ifdef CONFIG_VM86 ALIGN work_notifysig_v86: pushl_cfi %ecx # save ti_flags for do_notify_resume call save_v86_state # %eax contains pt_regs pointer popl_cfi %ecx movl %eax, %esp jmp 1b #endif END(work_pending) # perform syscall exit tracing ALIGN syscall_trace_entry: movl $-ENOSYS,PT_EAX(%esp) movl %esp, %eax call syscall_trace_enter /* What it returned is what we'll actually use. */ cmpl $(NR_syscalls), %eax jnae syscall_call jmp syscall_exit END(syscall_trace_entry) # perform syscall exit tracing ALIGN syscall_exit_work: testl $_TIF_WORK_SYSCALL_EXIT, %ecx jz work_pending TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_ANY) # could let syscall_trace_leave() call # schedule() instead movl %esp, %eax call syscall_trace_leave jmp resume_userspace END(syscall_exit_work) CFI_ENDPROC RING0_INT_FRAME # can't unwind into user space anyway syscall_fault: ASM_CLAC GET_THREAD_INFO(%ebp) movl $-EFAULT,PT_EAX(%esp) jmp resume_userspace END(syscall_fault) syscall_badsys: movl $-ENOSYS,PT_EAX(%esp) jmp resume_userspace END(syscall_badsys) CFI_ENDPROC /* * End of kprobes section */ .popsection /* * System calls that need a pt_regs pointer. */ #define PTREGSCALL0(name) \ ENTRY(ptregs_##name) ; \ leal 4(%esp),%eax; \ jmp sys_##name; \ ENDPROC(ptregs_##name) #define PTREGSCALL1(name) \ ENTRY(ptregs_##name) ; \ leal 4(%esp),%edx; \ movl (PT_EBX+4)(%esp),%eax; \ jmp sys_##name; \ ENDPROC(ptregs_##name) #define PTREGSCALL2(name) \ ENTRY(ptregs_##name) ; \ leal 4(%esp),%ecx; \ movl (PT_ECX+4)(%esp),%edx; \ movl (PT_EBX+4)(%esp),%eax; \ jmp sys_##name; \ ENDPROC(ptregs_##name) #define PTREGSCALL3(name) \ ENTRY(ptregs_##name) ; \ CFI_STARTPROC; \ leal 4(%esp),%eax; \ pushl_cfi %eax; \ movl PT_EDX(%eax),%ecx; \ movl PT_ECX(%eax),%edx; \ movl PT_EBX(%eax),%eax; \ call sys_##name; \ addl $4,%esp; \ CFI_ADJUST_CFA_OFFSET -4; \ ret; \ CFI_ENDPROC; \ ENDPROC(ptregs_##name) PTREGSCALL1(iopl) PTREGSCALL0(fork) PTREGSCALL0(vfork) PTREGSCALL2(sigaltstack) PTREGSCALL0(sigreturn) PTREGSCALL0(rt_sigreturn) PTREGSCALL2(vm86) PTREGSCALL1(vm86old) /* Clone is an oddball. The 4th arg is in %edi */ ENTRY(ptregs_clone) CFI_STARTPROC leal 4(%esp),%eax pushl_cfi %eax pushl_cfi PT_EDI(%eax) movl PT_EDX(%eax),%ecx movl PT_ECX(%eax),%edx movl PT_EBX(%eax),%eax call sys_clone addl $8,%esp CFI_ADJUST_CFA_OFFSET -8 ret CFI_ENDPROC ENDPROC(ptregs_clone) .macro FIXUP_ESPFIX_STACK /* * Switch back for ESPFIX stack to the normal zerobased stack * * We can't call C functions using the ESPFIX stack. This code reads * the high word of the segment base from the GDT and swiches to the * normal stack and adjusts ESP with the matching offset. */ /* fixup the stack */ mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */ mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */ shl $16, %eax addl %esp, %eax /* the adjusted stack pointer */ pushl_cfi $__KERNEL_DS pushl_cfi %eax lss (%esp), %esp /* switch to the normal stack segment */ CFI_ADJUST_CFA_OFFSET -8 .endm .macro UNWIND_ESPFIX_STACK movl %ss, %eax /* see if on espfix stack */ cmpw $__ESPFIX_SS, %ax jne 27f movl $__KERNEL_DS, %eax movl %eax, %ds movl %eax, %es /* switch to normal stack */ FIXUP_ESPFIX_STACK 27: .endm /* * Build the entry stubs and pointer table with some assembler magic. * We pack 7 stubs into a single 32-byte chunk, which will fit in a * single cache line on all modern x86 implementations. */ .section .init.rodata,"a" ENTRY(interrupt) .section .entry.text, "ax" .p2align 5 .p2align CONFIG_X86_L1_CACHE_SHIFT ENTRY(irq_entries_start) RING0_INT_FRAME vector=FIRST_EXTERNAL_VECTOR .rept (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7 .balign 32 .rept 7 .if vector < NR_VECTORS .if vector <> FIRST_EXTERNAL_VECTOR CFI_ADJUST_CFA_OFFSET -4 .endif 1: pushl_cfi $(~vector+0x80) /* Note: always in signed byte range */ .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6 jmp 2f .endif .previous .long 1b .section .entry.text, "ax" vector=vector+1 .endif .endr 2: jmp common_interrupt .endr END(irq_entries_start) .previous END(interrupt) .previous /* * the CPU automatically disables interrupts when executing an IRQ vector, * so IRQ-flags tracing has to follow that: */ .p2align CONFIG_X86_L1_CACHE_SHIFT common_interrupt: ASM_CLAC addl $-0x80,(%esp) /* Adjust vector into the [-256,-1] range */ SAVE_ALL TRACE_IRQS_OFF movl %esp,%eax call do_IRQ jmp ret_from_intr ENDPROC(common_interrupt) CFI_ENDPROC /* * Irq entries should be protected against kprobes */ .pushsection .kprobes.text, "ax" #define BUILD_INTERRUPT3(name, nr, fn) \ ENTRY(name) \ RING0_INT_FRAME; \ ASM_CLAC; \ pushl_cfi $~(nr); \ SAVE_ALL; \ TRACE_IRQS_OFF \ movl %esp,%eax; \ call fn; \ jmp ret_from_intr; \ CFI_ENDPROC; \ ENDPROC(name) #define BUILD_INTERRUPT(name, nr) BUILD_INTERRUPT3(name, nr, smp_##name) /* The include is where all of the SMP etc. interrupts come from */ #include ENTRY(coprocessor_error) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi $do_coprocessor_error jmp error_code CFI_ENDPROC END(coprocessor_error) ENTRY(simd_coprocessor_error) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 #ifdef CONFIG_X86_INVD_BUG /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */ 661: pushl_cfi $do_general_protection 662: .section .altinstructions,"a" altinstruction_entry 661b, 663f, X86_FEATURE_XMM, 662b-661b, 664f-663f .previous .section .altinstr_replacement,"ax" 663: pushl $do_simd_coprocessor_error 664: .previous #else pushl_cfi $do_simd_coprocessor_error #endif jmp error_code CFI_ENDPROC END(simd_coprocessor_error) ENTRY(device_not_available) RING0_INT_FRAME ASM_CLAC pushl_cfi $-1 # mark this as an int pushl_cfi $do_device_not_available jmp error_code CFI_ENDPROC END(device_not_available) #ifdef CONFIG_PARAVIRT ENTRY(native_iret) iret _ASM_EXTABLE(native_iret, iret_exc) END(native_iret) ENTRY(native_irq_enable_sysexit) sti sysexit END(native_irq_enable_sysexit) #endif ENTRY(overflow) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi $do_overflow jmp error_code CFI_ENDPROC END(overflow) ENTRY(bounds) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi $do_bounds jmp error_code CFI_ENDPROC END(bounds) ENTRY(invalid_op) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi $do_invalid_op jmp error_code CFI_ENDPROC END(invalid_op) ENTRY(coprocessor_segment_overrun) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi $do_coprocessor_segment_overrun jmp error_code CFI_ENDPROC END(coprocessor_segment_overrun) ENTRY(invalid_TSS) RING0_EC_FRAME ASM_CLAC pushl_cfi $do_invalid_TSS jmp error_code CFI_ENDPROC END(invalid_TSS) ENTRY(segment_not_present) RING0_EC_FRAME ASM_CLAC pushl_cfi $do_segment_not_present jmp error_code CFI_ENDPROC END(segment_not_present) ENTRY(stack_segment) RING0_EC_FRAME ASM_CLAC pushl_cfi $do_stack_segment jmp error_code CFI_ENDPROC END(stack_segment) ENTRY(alignment_check) RING0_EC_FRAME ASM_CLAC pushl_cfi $do_alignment_check jmp error_code CFI_ENDPROC END(alignment_check) ENTRY(divide_error) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 # no error code pushl_cfi $do_divide_error jmp error_code CFI_ENDPROC END(divide_error) #ifdef CONFIG_X86_MCE ENTRY(machine_check) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi machine_check_vector jmp error_code CFI_ENDPROC END(machine_check) #endif ENTRY(spurious_interrupt_bug) RING0_INT_FRAME ASM_CLAC pushl_cfi $0 pushl_cfi $do_spurious_interrupt_bug jmp error_code CFI_ENDPROC END(spurious_interrupt_bug) /* * End of kprobes section */ .popsection ENTRY(ret_from_kernel_thread) CFI_STARTPROC pushl_cfi %eax call schedule_tail GET_THREAD_INFO(%ebp) popl_cfi %eax pushl_cfi $0x0202 # Reset kernel eflags popfl_cfi movl PT_EBP(%esp),%eax call *PT_EBX(%esp) call do_exit ud2 # padding for call trace CFI_ENDPROC ENDPROC(ret_from_kernel_thread) #ifdef CONFIG_XEN /* Xen doesn't set %esp to be precisely what the normal sysenter entrypoint expects, so fix it up before using the normal path. */ ENTRY(xen_sysenter_target) RING0_INT_FRAME addl $5*4, %esp /* remove xen-provided frame */ CFI_ADJUST_CFA_OFFSET -5*4 jmp sysenter_past_esp CFI_ENDPROC ENTRY(xen_hypervisor_callback) CFI_STARTPROC pushl_cfi $0 SAVE_ALL TRACE_IRQS_OFF /* Check to see if we got the event in the critical region in xen_iret_direct, after we've reenabled events and checked for pending events. This simulates iret instruction's behaviour where it delivers a pending interrupt when enabling interrupts. */ movl PT_EIP(%esp),%eax cmpl $xen_iret_start_crit,%eax jb 1f cmpl $xen_iret_end_crit,%eax jae 1f jmp xen_iret_crit_fixup ENTRY(xen_do_upcall) 1: mov %esp, %eax call xen_evtchn_do_upcall jmp ret_from_intr CFI_ENDPROC ENDPROC(xen_hypervisor_callback) # Hypervisor uses this for application faults while it executes. # We get here for two reasons: # 1. Fault while reloading DS, ES, FS or GS # 2. Fault while executing IRET # Category 1 we fix up by reattempting the load, and zeroing the segment # register if the load fails. # Category 2 we fix up by jumping to do_iret_error. We cannot use the # normal Linux return path in this case because if we use the IRET hypercall # to pop the stack frame we end up in an infinite loop of failsafe callbacks. # We distinguish between categories by maintaining a status value in EAX. ENTRY(xen_failsafe_callback) CFI_STARTPROC pushl_cfi %eax movl $1,%eax 1: mov 4(%esp),%ds 2: mov 8(%esp),%es 3: mov 12(%esp),%fs 4: mov 16(%esp),%gs testl %eax,%eax popl_cfi %eax lea 16(%esp),%esp CFI_ADJUST_CFA_OFFSET -16 jz 5f addl $16,%esp jmp iret_exc # EAX != 0 => Category 2 (Bad IRET) 5: pushl_cfi $0 # EAX == 0 => Category 1 (Bad segment) SAVE_ALL jmp ret_from_exception CFI_ENDPROC .section .fixup,"ax" 6: xorl %eax,%eax movl %eax,4(%esp) jmp 1b 7: xorl %eax,%eax movl %eax,8(%esp) jmp 2b 8: xorl %eax,%eax movl %eax,12(%esp) jmp 3b 9: xorl %eax,%eax movl %eax,16(%esp) jmp 4b .previous _ASM_EXTABLE(1b,6b) _ASM_EXTABLE(2b,7b) _ASM_EXTABLE(3b,8b) _ASM_EXTABLE(4b,9b) ENDPROC(xen_failsafe_callback) BUILD_INTERRUPT3(xen_hvm_callback_vector, XEN_HVM_EVTCHN_CALLBACK, xen_evtchn_do_upcall) #endif /* CONFIG_XEN */ #ifdef CONFIG_FUNCTION_TRACER #ifdef CONFIG_DYNAMIC_FTRACE ENTRY(mcount) ret END(mcount) ENTRY(ftrace_caller) cmpl $0, function_trace_stop jne ftrace_stub pushl %eax pushl %ecx pushl %edx pushl $0 /* Pass NULL as regs pointer */ movl 4*4(%esp), %eax movl 0x4(%ebp), %edx leal function_trace_op, %ecx subl $MCOUNT_INSN_SIZE, %eax .globl ftrace_call ftrace_call: call ftrace_stub addl $4,%esp /* skip NULL pointer */ popl %edx popl %ecx popl %eax ftrace_ret: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call ftrace_graph_call: jmp ftrace_stub #endif .globl ftrace_stub ftrace_stub: ret END(ftrace_caller) ENTRY(ftrace_regs_caller) pushf /* push flags before compare (in cs location) */ cmpl $0, function_trace_stop jne ftrace_restore_flags /* * i386 does not save SS and ESP when coming from kernel. * Instead, to get sp, ®s->sp is used (see ptrace.h). * Unfortunately, that means eflags must be at the same location * as the current return ip is. We move the return ip into the * ip location, and move flags into the return ip location. */ pushl 4(%esp) /* save return ip into ip slot */ pushl $0 /* Load 0 into orig_ax */ pushl %gs pushl %fs pushl %es pushl %ds pushl %eax pushl %ebp pushl %edi pushl %esi pushl %edx pushl %ecx pushl %ebx movl 13*4(%esp), %eax /* Get the saved flags */ movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */ /* clobbering return ip */ movl $__KERNEL_CS,13*4(%esp) movl 12*4(%esp), %eax /* Load ip (1st parameter) */ subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */ movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ pushl %esp /* Save pt_regs as 4th parameter */ GLOBAL(ftrace_regs_call) call ftrace_stub addl $4, %esp /* Skip pt_regs */ movl 14*4(%esp), %eax /* Move flags back into cs */ movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */ movl 12*4(%esp), %eax /* Get return ip from regs->ip */ movl %eax, 14*4(%esp) /* Put return ip back for ret */ popl %ebx popl %ecx popl %edx popl %esi popl %edi popl %ebp popl %eax popl %ds popl %es popl %fs popl %gs addl $8, %esp /* Skip orig_ax and ip */ popf /* Pop flags at end (no addl to corrupt flags) */ jmp ftrace_ret ftrace_restore_flags: popf jmp ftrace_stub #else /* ! CONFIG_DYNAMIC_FTRACE */ ENTRY(mcount) cmpl $0, function_trace_stop jne ftrace_stub cmpl $ftrace_stub, ftrace_trace_function jnz trace #ifdef CONFIG_FUNCTION_GRAPH_TRACER cmpl $ftrace_stub, ftrace_graph_return jnz ftrace_graph_caller cmpl $ftrace_graph_entry_stub, ftrace_graph_entry jnz ftrace_graph_caller #endif .globl ftrace_stub ftrace_stub: ret /* taken from glibc */ trace: pushl %eax pushl %ecx pushl %edx movl 0xc(%esp), %eax movl 0x4(%ebp), %edx subl $MCOUNT_INSN_SIZE, %eax call *ftrace_trace_function popl %edx popl %ecx popl %eax jmp ftrace_stub END(mcount) #endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* CONFIG_FUNCTION_TRACER */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER ENTRY(ftrace_graph_caller) pushl %eax pushl %ecx pushl %edx movl 0xc(%esp), %edx lea 0x4(%ebp), %eax movl (%ebp), %ecx subl $MCOUNT_INSN_SIZE, %edx call prepare_ftrace_return popl %edx popl %ecx popl %eax ret END(ftrace_graph_caller) .globl return_to_handler return_to_handler: pushl %eax pushl %edx movl %ebp, %eax call ftrace_return_to_handler movl %eax, %ecx popl %edx popl %eax jmp *%ecx #endif /* * Some functions should be protected against kprobes */ .pushsection .kprobes.text, "ax" ENTRY(page_fault) RING0_EC_FRAME ASM_CLAC pushl_cfi $do_page_fault ALIGN error_code: /* the function address is in %gs's slot on the stack */ pushl_cfi %fs /*CFI_REL_OFFSET fs, 0*/ pushl_cfi %es /*CFI_REL_OFFSET es, 0*/ pushl_cfi %ds /*CFI_REL_OFFSET ds, 0*/ pushl_cfi %eax CFI_REL_OFFSET eax, 0 pushl_cfi %ebp CFI_REL_OFFSET ebp, 0 pushl_cfi %edi CFI_REL_OFFSET edi, 0 pushl_cfi %esi CFI_REL_OFFSET esi, 0 pushl_cfi %edx CFI_REL_OFFSET edx, 0 pushl_cfi %ecx CFI_REL_OFFSET ecx, 0 pushl_cfi %ebx CFI_REL_OFFSET ebx, 0 cld movl $(__KERNEL_PERCPU), %ecx movl %ecx, %fs UNWIND_ESPFIX_STACK GS_TO_REG %ecx movl PT_GS(%esp), %edi # get the function address movl PT_ORIG_EAX(%esp), %edx # get the error code movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart REG_TO_PTGS %ecx SET_KERNEL_GS %ecx movl $(__USER_DS), %ecx movl %ecx, %ds movl %ecx, %es TRACE_IRQS_OFF movl %esp,%eax # pt_regs pointer call *%edi jmp ret_from_exception CFI_ENDPROC END(page_fault) /* * Debug traps and NMI can happen at the one SYSENTER instruction * that sets up the real kernel stack. Check here, since we can't * allow the wrong stack to be used. * * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have * already pushed 3 words if it hits on the sysenter instruction: * eflags, cs and eip. * * We just load the right stack, and push the three (known) values * by hand onto the new stack - while updating the return eip past * the instruction that would have done it for sysenter. */ .macro FIX_STACK offset ok label cmpw $__KERNEL_CS, 4(%esp) jne \ok \label: movl TSS_sysenter_sp0 + \offset(%esp), %esp CFI_DEF_CFA esp, 0 CFI_UNDEFINED eip pushfl_cfi pushl_cfi $__KERNEL_CS pushl_cfi $sysenter_past_esp CFI_REL_OFFSET eip, 0 .endm ENTRY(debug) RING0_INT_FRAME ASM_CLAC cmpl $ia32_sysenter_target,(%esp) jne debug_stack_correct FIX_STACK 12, debug_stack_correct, debug_esp_fix_insn debug_stack_correct: pushl_cfi $-1 # mark this as an int SAVE_ALL TRACE_IRQS_OFF xorl %edx,%edx # error code 0 movl %esp,%eax # pt_regs pointer call do_debug jmp ret_from_exception CFI_ENDPROC END(debug) /* * NMI is doubly nasty. It can happen _while_ we're handling * a debug fault, and the debug fault hasn't yet been able to * clear up the stack. So we first check whether we got an * NMI on the sysenter entry path, but after that we need to * check whether we got an NMI on the debug path where the debug * fault happened on the sysenter path. */ ENTRY(nmi) RING0_INT_FRAME ASM_CLAC pushl_cfi %eax movl %ss, %eax cmpw $__ESPFIX_SS, %ax popl_cfi %eax je nmi_espfix_stack cmpl $ia32_sysenter_target,(%esp) je nmi_stack_fixup pushl_cfi %eax movl %esp,%eax /* Do not access memory above the end of our stack page, * it might not exist. */ andl $(THREAD_SIZE-1),%eax cmpl $(THREAD_SIZE-20),%eax popl_cfi %eax jae nmi_stack_correct cmpl $ia32_sysenter_target,12(%esp) je nmi_debug_stack_check nmi_stack_correct: /* We have a RING0_INT_FRAME here */ pushl_cfi %eax SAVE_ALL xorl %edx,%edx # zero error code movl %esp,%eax # pt_regs pointer call do_nmi jmp restore_all_notrace CFI_ENDPROC nmi_stack_fixup: RING0_INT_FRAME FIX_STACK 12, nmi_stack_correct, 1 jmp nmi_stack_correct nmi_debug_stack_check: /* We have a RING0_INT_FRAME here */ cmpw $__KERNEL_CS,16(%esp) jne nmi_stack_correct cmpl $debug,(%esp) jb nmi_stack_correct cmpl $debug_esp_fix_insn,(%esp) ja nmi_stack_correct FIX_STACK 24, nmi_stack_correct, 1 jmp nmi_stack_correct nmi_espfix_stack: /* We have a RING0_INT_FRAME here. * * create the pointer to lss back */ pushl_cfi %ss pushl_cfi %esp addl $4, (%esp) /* copy the iret frame of 12 bytes */ .rept 3 pushl_cfi 16(%esp) .endr pushl_cfi %eax SAVE_ALL FIXUP_ESPFIX_STACK # %eax == %esp xorl %edx,%edx # zero error code call do_nmi RESTORE_REGS lss 12+4(%esp), %esp # back to espfix stack CFI_ADJUST_CFA_OFFSET -24 jmp irq_return CFI_ENDPROC END(nmi) ENTRY(int3) RING0_INT_FRAME ASM_CLAC pushl_cfi $-1 # mark this as an int SAVE_ALL TRACE_IRQS_OFF xorl %edx,%edx # zero error code movl %esp,%eax # pt_regs pointer call do_int3 jmp ret_from_exception CFI_ENDPROC END(int3) ENTRY(general_protection) RING0_EC_FRAME pushl_cfi $do_general_protection jmp error_code CFI_ENDPROC END(general_protection) #ifdef CONFIG_KVM_GUEST ENTRY(async_page_fault) RING0_EC_FRAME ASM_CLAC pushl_cfi $do_async_page_fault jmp error_code CFI_ENDPROC END(async_page_fault) #endif /* * End of kprobes section */ .popsection