/* * linux/arch/x86_64/entry.S * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs * Copyright (C) 2000 Pavel Machek */ /* * entry.S contains the system-call and fault low-level handling routines. * * Some of this is documented in Documentation/x86/entry_64.txt * * NOTE: This code handles signal-recognition, which happens every time * after an interrupt and after each system call. * * A note on terminology: * - top of stack: Architecture defined interrupt frame from SS to RIP * at the top of the kernel process stack. * - partial stack frame: partially saved registers up to R11. * - full stack frame: Like partial stack frame, but all register saved. * * Some macro usage: * - CFI macros are used to generate dwarf2 unwind information for better * backtraces. They don't change any code. * - ENTRY/END Define functions in the symbol table. * - FIXUP_TOP_OF_STACK/RESTORE_TOP_OF_STACK - Fix up the hardware stack * frame that is otherwise undefined after a SYSCALL * - TRACE_IRQ_* - Trace hard interrupt state for lock debugging. * - idtentry - Define exception entry points. */ #include #include #include #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_X86_64 (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE) #define __AUDIT_ARCH_64BIT 0x80000000 #define __AUDIT_ARCH_LE 0x40000000 .code64 .section .entry.text, "ax" #ifndef CONFIG_PREEMPT #define retint_kernel retint_restore_args #endif #ifdef CONFIG_PARAVIRT ENTRY(native_usergs_sysret64) swapgs sysretq ENDPROC(native_usergs_sysret64) #endif /* CONFIG_PARAVIRT */ .macro TRACE_IRQS_IRETQ #ifdef CONFIG_TRACE_IRQFLAGS bt $9,EFLAGS(%rsp) /* interrupts off? */ jnc 1f TRACE_IRQS_ON 1: #endif .endm /* * When dynamic function tracer is enabled it will add a breakpoint * to all locations that it is about to modify, sync CPUs, update * all the code, sync CPUs, then remove the breakpoints. In this time * if lockdep is enabled, it might jump back into the debug handler * outside the updating of the IST protection. (TRACE_IRQS_ON/OFF). * * We need to change the IDT table before calling TRACE_IRQS_ON/OFF to * make sure the stack pointer does not get reset back to the top * of the debug stack, and instead just reuses the current stack. */ #if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_TRACE_IRQFLAGS) .macro TRACE_IRQS_OFF_DEBUG call debug_stack_set_zero TRACE_IRQS_OFF call debug_stack_reset .endm .macro TRACE_IRQS_ON_DEBUG call debug_stack_set_zero TRACE_IRQS_ON call debug_stack_reset .endm .macro TRACE_IRQS_IRETQ_DEBUG bt $9,EFLAGS(%rsp) /* interrupts off? */ jnc 1f TRACE_IRQS_ON_DEBUG 1: .endm #else # define TRACE_IRQS_OFF_DEBUG TRACE_IRQS_OFF # define TRACE_IRQS_ON_DEBUG TRACE_IRQS_ON # define TRACE_IRQS_IRETQ_DEBUG TRACE_IRQS_IRETQ #endif /* * C code is not supposed to know about undefined top of stack. Every time * a C function with an pt_regs argument is called from the SYSCALL based * fast path FIXUP_TOP_OF_STACK is needed. * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs * manipulation. */ /* %rsp:at FRAMEEND */ .macro FIXUP_TOP_OF_STACK tmp offset=0 movq PER_CPU_VAR(old_rsp),\tmp movq \tmp,RSP+\offset(%rsp) movq $__USER_DS,SS+\offset(%rsp) movq $__USER_CS,CS+\offset(%rsp) movq RIP+\offset(%rsp),\tmp /* get rip */ movq \tmp,RCX+\offset(%rsp) /* copy it to rcx as sysret would do */ movq R11+\offset(%rsp),\tmp /* get eflags */ movq \tmp,EFLAGS+\offset(%rsp) .endm .macro RESTORE_TOP_OF_STACK tmp offset=0 movq RSP+\offset(%rsp),\tmp movq \tmp,PER_CPU_VAR(old_rsp) movq EFLAGS+\offset(%rsp),\tmp movq \tmp,R11+\offset(%rsp) .endm /* * empty frame */ .macro EMPTY_FRAME start=1 offset=0 .if \start CFI_STARTPROC simple CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,8+\offset .else CFI_DEF_CFA_OFFSET 8+\offset .endif .endm /* * initial frame state for interrupts (and exceptions without error code) */ .macro INTR_FRAME start=1 offset=0 EMPTY_FRAME \start, 5*8+\offset /*CFI_REL_OFFSET ss, 4*8+\offset*/ CFI_REL_OFFSET rsp, 3*8+\offset /*CFI_REL_OFFSET rflags, 2*8+\offset*/ /*CFI_REL_OFFSET cs, 1*8+\offset*/ CFI_REL_OFFSET rip, 0*8+\offset .endm /* * initial frame state for exceptions with error code (and interrupts * with vector already pushed) */ .macro XCPT_FRAME start=1 offset=0 INTR_FRAME \start, 1*8+\offset .endm /* * frame that enables passing a complete pt_regs to a C function. */ .macro DEFAULT_FRAME start=1 offset=0 XCPT_FRAME \start, ORIG_RAX+\offset CFI_REL_OFFSET rdi, RDI+\offset CFI_REL_OFFSET rsi, RSI+\offset CFI_REL_OFFSET rdx, RDX+\offset CFI_REL_OFFSET rcx, RCX+\offset CFI_REL_OFFSET rax, RAX+\offset CFI_REL_OFFSET r8, R8+\offset CFI_REL_OFFSET r9, R9+\offset CFI_REL_OFFSET r10, R10+\offset CFI_REL_OFFSET r11, R11+\offset CFI_REL_OFFSET rbx, RBX+\offset CFI_REL_OFFSET rbp, RBP+\offset CFI_REL_OFFSET r12, R12+\offset CFI_REL_OFFSET r13, R13+\offset CFI_REL_OFFSET r14, R14+\offset CFI_REL_OFFSET r15, R15+\offset .endm /* * 64bit SYSCALL instruction entry. Up to 6 arguments in registers. * * 64bit SYSCALL saves rip to rcx, clears rflags.RF, then saves rflags to r11, * then loads new ss, cs, and rip from previously programmed MSRs. * rflags gets masked by a value from another MSR (so CLD and CLAC * are not needed). SYSCALL does not save anything on the stack * and does not change rsp. * * Registers on entry: * rax system call number * rcx return address * r11 saved rflags (note: r11 is callee-clobbered register in C ABI) * rdi arg0 * rsi arg1 * rdx arg2 * r10 arg3 (needs to be moved to rcx to conform to C ABI) * r8 arg4 * r9 arg5 * (note: r12-r15,rbp,rbx are callee-preserved in C ABI) * * Interrupts are off on entry. * Only called from user space. * * XXX if we had a free scratch register we could save the RSP into the stack frame * and report it properly in ps. Unfortunately we haven't. * * When user can change the frames always force IRET. That is because * it deals with uncanonical addresses better. SYSRET has trouble * with them due to bugs in both AMD and Intel CPUs. */ ENTRY(system_call) CFI_STARTPROC simple CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,KERNEL_STACK_OFFSET CFI_REGISTER rip,rcx /*CFI_REGISTER rflags,r11*/ SWAPGS_UNSAFE_STACK /* * A hypervisor implementation might want to use a label * after the swapgs, so that it can do the swapgs * for the guest and jump here on syscall. */ GLOBAL(system_call_after_swapgs) movq %rsp,PER_CPU_VAR(old_rsp) /* kernel_stack is set so that 5 slots (iret frame) are preallocated */ movq PER_CPU_VAR(kernel_stack),%rsp /* * No need to follow this irqs off/on section - it's straight * and short: */ ENABLE_INTERRUPTS(CLBR_NONE) ALLOC_PT_GPREGS_ON_STACK 8 /* +8: space for orig_ax */ SAVE_C_REGS_EXCEPT_RAX_RCX movq $-ENOSYS,RAX(%rsp) movq_cfi rax,ORIG_RAX movq %rcx,RIP(%rsp) CFI_REL_OFFSET rip,RIP testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP) jnz tracesys system_call_fastpath: #if __SYSCALL_MASK == ~0 cmpq $__NR_syscall_max,%rax #else andl $__SYSCALL_MASK,%eax cmpl $__NR_syscall_max,%eax #endif ja ret_from_sys_call /* and return regs->ax */ movq %r10,%rcx call *sys_call_table(,%rax,8) # XXX: rip relative movq %rax,RAX(%rsp) /* * Syscall return path ending with SYSRET (fast path) * Has incomplete stack frame and undefined top of stack. */ ret_from_sys_call: testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP) jnz int_ret_from_sys_call_fixup /* Go the the slow path */ LOCKDEP_SYS_EXIT DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF CFI_REMEMBER_STATE /* * sysretq will re-enable interrupts: */ TRACE_IRQS_ON RESTORE_C_REGS_EXCEPT_RCX movq RIP(%rsp),%rcx CFI_REGISTER rip,rcx /*CFI_REGISTER rflags,r11*/ movq PER_CPU_VAR(old_rsp), %rsp /* * 64bit SYSRET restores rip from rcx, * rflags from r11 (but RF and VM bits are forced to 0), * cs and ss are loaded from MSRs. */ USERGS_SYSRET64 CFI_RESTORE_STATE int_ret_from_sys_call_fixup: FIXUP_TOP_OF_STACK %r11 jmp int_ret_from_sys_call /* Do syscall tracing */ tracesys: movq %rsp, %rdi movq $AUDIT_ARCH_X86_64, %rsi call syscall_trace_enter_phase1 test %rax, %rax jnz tracesys_phase2 /* if needed, run the slow path */ RESTORE_C_REGS_EXCEPT_RAX /* else restore clobbered regs */ movq ORIG_RAX(%rsp), %rax jmp system_call_fastpath /* and return to the fast path */ tracesys_phase2: SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %rdi movq %rsp, %rdi movq $AUDIT_ARCH_X86_64, %rsi movq %rax,%rdx call syscall_trace_enter_phase2 /* * Reload registers from stack in case ptrace changed them. * We don't reload %rax because syscall_trace_entry_phase2() returned * the value it wants us to use in the table lookup. */ RESTORE_C_REGS_EXCEPT_RAX RESTORE_EXTRA_REGS #if __SYSCALL_MASK == ~0 cmpq $__NR_syscall_max,%rax #else andl $__SYSCALL_MASK,%eax cmpl $__NR_syscall_max,%eax #endif ja int_ret_from_sys_call /* RAX(%rsp) is already set */ movq %r10,%rcx /* fixup for C */ call *sys_call_table(,%rax,8) movq %rax,RAX(%rsp) /* Use IRET because user could have changed frame */ /* * Syscall return path ending with IRET. * Has correct top of stack, but partial stack frame. */ GLOBAL(int_ret_from_sys_call) DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF movl $_TIF_ALLWORK_MASK,%edi /* edi: mask to check */ GLOBAL(int_with_check) LOCKDEP_SYS_EXIT_IRQ GET_THREAD_INFO(%rcx) movl TI_flags(%rcx),%edx andl %edi,%edx jnz int_careful andl $~TS_COMPAT,TI_status(%rcx) jmp retint_swapgs /* Either reschedule or signal or syscall exit tracking needed. */ /* First do a reschedule test. */ /* edx: work, edi: workmask */ int_careful: bt $TIF_NEED_RESCHED,%edx jnc int_very_careful TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) pushq_cfi %rdi SCHEDULE_USER popq_cfi %rdi DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp int_with_check /* handle signals and tracing -- both require a full stack frame */ int_very_careful: TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) SAVE_EXTRA_REGS /* Check for syscall exit trace */ testl $_TIF_WORK_SYSCALL_EXIT,%edx jz int_signal pushq_cfi %rdi leaq 8(%rsp),%rdi # &ptregs -> arg1 call syscall_trace_leave popq_cfi %rdi andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi jmp int_restore_rest int_signal: testl $_TIF_DO_NOTIFY_MASK,%edx jz 1f movq %rsp,%rdi # &ptregs -> arg1 xorl %esi,%esi # oldset -> arg2 call do_notify_resume 1: movl $_TIF_WORK_MASK,%edi int_restore_rest: RESTORE_EXTRA_REGS DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp int_with_check CFI_ENDPROC END(system_call) .macro FORK_LIKE func ENTRY(stub_\func) CFI_STARTPROC DEFAULT_FRAME 0, 8 /* offset 8: return address */ SAVE_EXTRA_REGS 8 FIXUP_TOP_OF_STACK %r11, 8 call sys_\func RESTORE_TOP_OF_STACK %r11, 8 ret CFI_ENDPROC END(stub_\func) .endm .macro FIXED_FRAME label,func ENTRY(\label) CFI_STARTPROC DEFAULT_FRAME 0, 8 /* offset 8: return address */ FIXUP_TOP_OF_STACK %r11, 8 call \func RESTORE_TOP_OF_STACK %r11, 8 ret CFI_ENDPROC END(\label) .endm FORK_LIKE clone FORK_LIKE fork FORK_LIKE vfork FIXED_FRAME stub_iopl, sys_iopl ENTRY(stub_execve) CFI_STARTPROC addq $8, %rsp DEFAULT_FRAME 0 SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %r11 call sys_execve movq %rax,RAX(%rsp) RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(stub_execve) ENTRY(stub_execveat) CFI_STARTPROC addq $8, %rsp DEFAULT_FRAME 0 SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %r11 call sys_execveat RESTORE_TOP_OF_STACK %r11 movq %rax,RAX(%rsp) RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(stub_execveat) /* * sigreturn is special because it needs to restore all registers on return. * This cannot be done with SYSRET, so use the IRET return path instead. */ ENTRY(stub_rt_sigreturn) CFI_STARTPROC addq $8, %rsp DEFAULT_FRAME 0 SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %r11 call sys_rt_sigreturn movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(stub_rt_sigreturn) #ifdef CONFIG_X86_X32_ABI ENTRY(stub_x32_rt_sigreturn) CFI_STARTPROC addq $8, %rsp DEFAULT_FRAME 0 SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %r11 call sys32_x32_rt_sigreturn movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(stub_x32_rt_sigreturn) ENTRY(stub_x32_execve) CFI_STARTPROC addq $8, %rsp DEFAULT_FRAME 0 SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %r11 call compat_sys_execve RESTORE_TOP_OF_STACK %r11 movq %rax,RAX(%rsp) RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(stub_x32_execve) ENTRY(stub_x32_execveat) CFI_STARTPROC addq $8, %rsp DEFAULT_FRAME 0 SAVE_EXTRA_REGS FIXUP_TOP_OF_STACK %r11 call compat_sys_execveat RESTORE_TOP_OF_STACK %r11 movq %rax,RAX(%rsp) RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(stub_x32_execveat) #endif /* * A newly forked process directly context switches into this address. * * rdi: prev task we switched from */ ENTRY(ret_from_fork) DEFAULT_FRAME LOCK ; btr $TIF_FORK,TI_flags(%r8) pushq_cfi $0x0002 popfq_cfi # reset kernel eflags call schedule_tail # rdi: 'prev' task parameter GET_THREAD_INFO(%rcx) RESTORE_EXTRA_REGS testl $3,CS(%rsp) # from kernel_thread? jz 1f testl $_TIF_IA32, TI_flags(%rcx) # 32-bit compat task needs IRET jnz int_ret_from_sys_call RESTORE_TOP_OF_STACK %rdi jmp ret_from_sys_call # go to the SYSRET fastpath 1: movq %rbp, %rdi call *%rbx movl $0, RAX(%rsp) RESTORE_EXTRA_REGS jmp int_ret_from_sys_call CFI_ENDPROC END(ret_from_fork) /* * 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 .p2align 5 .p2align CONFIG_X86_L1_CACHE_SHIFT ENTRY(irq_entries_start) INTR_FRAME vector=FIRST_EXTERNAL_VECTOR .rept (FIRST_SYSTEM_VECTOR-FIRST_EXTERNAL_VECTOR+6)/7 .balign 32 .rept 7 .if vector < FIRST_SYSTEM_VECTOR .if vector <> FIRST_EXTERNAL_VECTOR CFI_ADJUST_CFA_OFFSET -8 .endif 1: pushq_cfi $(~vector+0x80) /* Note: always in signed byte range */ .if ((vector-FIRST_EXTERNAL_VECTOR)%7) <> 6 jmp 2f .endif .previous .quad 1b .section .entry.text vector=vector+1 .endif .endr 2: jmp common_interrupt .endr CFI_ENDPROC END(irq_entries_start) .previous END(interrupt) .previous /* * Interrupt entry/exit. * * Interrupt entry points save only callee clobbered registers in fast path. * * Entry runs with interrupts off. */ /* 0(%rsp): ~(interrupt number) */ .macro interrupt func cld /* * Since nothing in interrupt handling code touches r12...r15 members * of "struct pt_regs", and since interrupts can nest, we can save * four stack slots and simultaneously provide * an unwind-friendly stack layout by saving "truncated" pt_regs * exactly up to rbp slot, without these members. */ ALLOC_PT_GPREGS_ON_STACK -RBP SAVE_C_REGS -RBP /* this goes to 0(%rsp) for unwinder, not for saving the value: */ SAVE_EXTRA_REGS_RBP -RBP leaq -RBP(%rsp),%rdi /* arg1 for \func (pointer to pt_regs) */ testl $3, CS-RBP(%rsp) je 1f SWAPGS 1: /* * Save previous stack pointer, optionally switch to interrupt stack. * irq_count is used to check if a CPU is already on an interrupt stack * or not. While this is essentially redundant with preempt_count it is * a little cheaper to use a separate counter in the PDA (short of * moving irq_enter into assembly, which would be too much work) */ movq %rsp, %rsi incl PER_CPU_VAR(irq_count) cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp CFI_DEF_CFA_REGISTER rsi pushq %rsi /* * For debugger: * "CFA (Current Frame Address) is the value on stack + offset" */ CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \ 0x77 /* DW_OP_breg7 (rsp) */, 0, \ 0x06 /* DW_OP_deref */, \ 0x08 /* DW_OP_const1u */, SIZEOF_PTREGS-RBP, \ 0x22 /* DW_OP_plus */ /* We entered an interrupt context - irqs are off: */ TRACE_IRQS_OFF call \func .endm /* * The interrupt stubs push (~vector+0x80) onto the stack and * then jump to common_interrupt. */ .p2align CONFIG_X86_L1_CACHE_SHIFT common_interrupt: XCPT_FRAME ASM_CLAC addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */ interrupt do_IRQ /* 0(%rsp): old_rsp */ ret_from_intr: DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF decl PER_CPU_VAR(irq_count) /* Restore saved previous stack */ popq %rsi CFI_DEF_CFA rsi,SIZEOF_PTREGS-RBP /* reg/off reset after def_cfa_expr */ /* return code expects complete pt_regs - adjust rsp accordingly: */ leaq -RBP(%rsi),%rsp CFI_DEF_CFA_REGISTER rsp CFI_ADJUST_CFA_OFFSET RBP exit_intr: GET_THREAD_INFO(%rcx) testl $3,CS(%rsp) je retint_kernel /* Interrupt came from user space */ /* * Has a correct top of stack. * %rcx: thread info. Interrupts off. */ retint_with_reschedule: movl $_TIF_WORK_MASK,%edi retint_check: LOCKDEP_SYS_EXIT_IRQ movl TI_flags(%rcx),%edx andl %edi,%edx CFI_REMEMBER_STATE jnz retint_careful retint_swapgs: /* return to user-space */ /* * The iretq could re-enable interrupts: */ DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_IRETQ /* * Try to use SYSRET instead of IRET if we're returning to * a completely clean 64-bit userspace context. */ movq RCX(%rsp),%rcx cmpq %rcx,RIP(%rsp) /* RCX == RIP */ jne opportunistic_sysret_failed /* * On Intel CPUs, sysret with non-canonical RCX/RIP will #GP * in kernel space. This essentially lets the user take over * the kernel, since userspace controls RSP. It's not worth * testing for canonicalness exactly -- this check detects any * of the 17 high bits set, which is true for non-canonical * or kernel addresses. (This will pessimize vsyscall=native. * Big deal.) * * If virtual addresses ever become wider, this will need * to be updated to remain correct on both old and new CPUs. */ .ifne __VIRTUAL_MASK_SHIFT - 47 .error "virtual address width changed -- sysret checks need update" .endif shr $__VIRTUAL_MASK_SHIFT, %rcx jnz opportunistic_sysret_failed cmpq $__USER_CS,CS(%rsp) /* CS must match SYSRET */ jne opportunistic_sysret_failed movq R11(%rsp),%r11 cmpq %r11,EFLAGS(%rsp) /* R11 == RFLAGS */ jne opportunistic_sysret_failed testq $X86_EFLAGS_RF,%r11 /* sysret can't restore RF */ jnz opportunistic_sysret_failed /* nothing to check for RSP */ cmpq $__USER_DS,SS(%rsp) /* SS must match SYSRET */ jne opportunistic_sysret_failed /* * We win! This label is here just for ease of understanding * perf profiles. Nothing jumps here. */ irq_return_via_sysret: CFI_REMEMBER_STATE RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 movq (RSP-RIP)(%rsp),%rsp USERGS_SYSRET64 CFI_RESTORE_STATE opportunistic_sysret_failed: SWAPGS jmp restore_args retint_restore_args: /* return to kernel space */ DISABLE_INTERRUPTS(CLBR_ANY) /* * The iretq could re-enable interrupts: */ TRACE_IRQS_IRETQ restore_args: RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 irq_return: INTERRUPT_RETURN ENTRY(native_iret) /* * Are we returning to a stack segment from the LDT? Note: in * 64-bit mode SS:RSP on the exception stack is always valid. */ #ifdef CONFIG_X86_ESPFIX64 testb $4,(SS-RIP)(%rsp) jnz native_irq_return_ldt #endif .global native_irq_return_iret native_irq_return_iret: /* * This may fault. Non-paranoid faults on return to userspace are * handled by fixup_bad_iret. These include #SS, #GP, and #NP. * Double-faults due to espfix64 are handled in do_double_fault. * Other faults here are fatal. */ iretq #ifdef CONFIG_X86_ESPFIX64 native_irq_return_ldt: pushq_cfi %rax pushq_cfi %rdi SWAPGS movq PER_CPU_VAR(espfix_waddr),%rdi movq %rax,(0*8)(%rdi) /* RAX */ movq (2*8)(%rsp),%rax /* RIP */ movq %rax,(1*8)(%rdi) movq (3*8)(%rsp),%rax /* CS */ movq %rax,(2*8)(%rdi) movq (4*8)(%rsp),%rax /* RFLAGS */ movq %rax,(3*8)(%rdi) movq (6*8)(%rsp),%rax /* SS */ movq %rax,(5*8)(%rdi) movq (5*8)(%rsp),%rax /* RSP */ movq %rax,(4*8)(%rdi) andl $0xffff0000,%eax popq_cfi %rdi orq PER_CPU_VAR(espfix_stack),%rax SWAPGS movq %rax,%rsp popq_cfi %rax jmp native_irq_return_iret #endif /* edi: workmask, edx: work */ retint_careful: CFI_RESTORE_STATE bt $TIF_NEED_RESCHED,%edx jnc retint_signal TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) pushq_cfi %rdi SCHEDULE_USER popq_cfi %rdi GET_THREAD_INFO(%rcx) DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp retint_check retint_signal: testl $_TIF_DO_NOTIFY_MASK,%edx jz retint_swapgs TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) SAVE_EXTRA_REGS movq $-1,ORIG_RAX(%rsp) xorl %esi,%esi # oldset movq %rsp,%rdi # &pt_regs call do_notify_resume RESTORE_EXTRA_REGS DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF GET_THREAD_INFO(%rcx) jmp retint_with_reschedule #ifdef CONFIG_PREEMPT /* Returning to kernel space. Check if we need preemption */ /* rcx: threadinfo. interrupts off. */ ENTRY(retint_kernel) cmpl $0,PER_CPU_VAR(__preempt_count) jnz retint_restore_args bt $9,EFLAGS(%rsp) /* interrupts off? */ jnc retint_restore_args call preempt_schedule_irq jmp exit_intr #endif CFI_ENDPROC END(common_interrupt) /* * APIC interrupts. */ .macro apicinterrupt3 num sym do_sym ENTRY(\sym) INTR_FRAME ASM_CLAC pushq_cfi $~(\num) .Lcommon_\sym: interrupt \do_sym jmp ret_from_intr CFI_ENDPROC END(\sym) .endm #ifdef CONFIG_TRACING #define trace(sym) trace_##sym #define smp_trace(sym) smp_trace_##sym .macro trace_apicinterrupt num sym apicinterrupt3 \num trace(\sym) smp_trace(\sym) .endm #else .macro trace_apicinterrupt num sym do_sym .endm #endif .macro apicinterrupt num sym do_sym apicinterrupt3 \num \sym \do_sym trace_apicinterrupt \num \sym .endm #ifdef CONFIG_SMP apicinterrupt3 IRQ_MOVE_CLEANUP_VECTOR \ irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt apicinterrupt3 REBOOT_VECTOR \ reboot_interrupt smp_reboot_interrupt #endif #ifdef CONFIG_X86_UV apicinterrupt3 UV_BAU_MESSAGE \ uv_bau_message_intr1 uv_bau_message_interrupt #endif apicinterrupt LOCAL_TIMER_VECTOR \ apic_timer_interrupt smp_apic_timer_interrupt apicinterrupt X86_PLATFORM_IPI_VECTOR \ x86_platform_ipi smp_x86_platform_ipi #ifdef CONFIG_HAVE_KVM apicinterrupt3 POSTED_INTR_VECTOR \ kvm_posted_intr_ipi smp_kvm_posted_intr_ipi #endif #ifdef CONFIG_X86_MCE_THRESHOLD apicinterrupt THRESHOLD_APIC_VECTOR \ threshold_interrupt smp_threshold_interrupt #endif #ifdef CONFIG_X86_THERMAL_VECTOR apicinterrupt THERMAL_APIC_VECTOR \ thermal_interrupt smp_thermal_interrupt #endif #ifdef CONFIG_SMP apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \ call_function_single_interrupt smp_call_function_single_interrupt apicinterrupt CALL_FUNCTION_VECTOR \ call_function_interrupt smp_call_function_interrupt apicinterrupt RESCHEDULE_VECTOR \ reschedule_interrupt smp_reschedule_interrupt #endif apicinterrupt ERROR_APIC_VECTOR \ error_interrupt smp_error_interrupt apicinterrupt SPURIOUS_APIC_VECTOR \ spurious_interrupt smp_spurious_interrupt #ifdef CONFIG_IRQ_WORK apicinterrupt IRQ_WORK_VECTOR \ irq_work_interrupt smp_irq_work_interrupt #endif /* * Exception entry points. */ #define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8) .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ENTRY(\sym) /* Sanity check */ .if \shift_ist != -1 && \paranoid == 0 .error "using shift_ist requires paranoid=1" .endif .if \has_error_code XCPT_FRAME .else INTR_FRAME .endif ASM_CLAC PARAVIRT_ADJUST_EXCEPTION_FRAME .ifeq \has_error_code pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */ .endif ALLOC_PT_GPREGS_ON_STACK .if \paranoid .if \paranoid == 1 CFI_REMEMBER_STATE testl $3, CS(%rsp) /* If coming from userspace, switch */ jnz 1f /* stacks. */ .endif call paranoid_entry .else call error_entry .endif /* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */ DEFAULT_FRAME 0 .if \paranoid .if \shift_ist != -1 TRACE_IRQS_OFF_DEBUG /* reload IDT in case of recursion */ .else TRACE_IRQS_OFF .endif .endif movq %rsp,%rdi /* pt_regs pointer */ .if \has_error_code movq ORIG_RAX(%rsp),%rsi /* get error code */ movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */ .else xorl %esi,%esi /* no error code */ .endif .if \shift_ist != -1 subq $EXCEPTION_STKSZ, INIT_TSS_IST(\shift_ist) .endif call \do_sym .if \shift_ist != -1 addq $EXCEPTION_STKSZ, INIT_TSS_IST(\shift_ist) .endif /* these procedures expect "no swapgs" flag in ebx */ .if \paranoid jmp paranoid_exit .else jmp error_exit .endif .if \paranoid == 1 CFI_RESTORE_STATE /* * Paranoid entry from userspace. Switch stacks and treat it * as a normal entry. This means that paranoid handlers * run in real process context if user_mode(regs). */ 1: call error_entry DEFAULT_FRAME 0 movq %rsp,%rdi /* pt_regs pointer */ call sync_regs movq %rax,%rsp /* switch stack */ movq %rsp,%rdi /* pt_regs pointer */ .if \has_error_code movq ORIG_RAX(%rsp),%rsi /* get error code */ movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */ .else xorl %esi,%esi /* no error code */ .endif call \do_sym jmp error_exit /* %ebx: no swapgs flag */ .endif CFI_ENDPROC END(\sym) .endm #ifdef CONFIG_TRACING .macro trace_idtentry sym do_sym has_error_code:req idtentry trace(\sym) trace(\do_sym) has_error_code=\has_error_code idtentry \sym \do_sym has_error_code=\has_error_code .endm #else .macro trace_idtentry sym do_sym has_error_code:req idtentry \sym \do_sym has_error_code=\has_error_code .endm #endif idtentry divide_error do_divide_error has_error_code=0 idtentry overflow do_overflow has_error_code=0 idtentry bounds do_bounds has_error_code=0 idtentry invalid_op do_invalid_op has_error_code=0 idtentry device_not_available do_device_not_available has_error_code=0 idtentry double_fault do_double_fault has_error_code=1 paranoid=2 idtentry coprocessor_segment_overrun do_coprocessor_segment_overrun has_error_code=0 idtentry invalid_TSS do_invalid_TSS has_error_code=1 idtentry segment_not_present do_segment_not_present has_error_code=1 idtentry spurious_interrupt_bug do_spurious_interrupt_bug has_error_code=0 idtentry coprocessor_error do_coprocessor_error has_error_code=0 idtentry alignment_check do_alignment_check has_error_code=1 idtentry simd_coprocessor_error do_simd_coprocessor_error has_error_code=0 /* Reload gs selector with exception handling */ /* edi: new selector */ ENTRY(native_load_gs_index) CFI_STARTPROC pushfq_cfi DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI) SWAPGS gs_change: movl %edi,%gs 2: mfence /* workaround */ SWAPGS popfq_cfi ret CFI_ENDPROC END(native_load_gs_index) _ASM_EXTABLE(gs_change,bad_gs) .section .fixup,"ax" /* running with kernelgs */ bad_gs: SWAPGS /* switch back to user gs */ xorl %eax,%eax movl %eax,%gs jmp 2b .previous /* Call softirq on interrupt stack. Interrupts are off. */ ENTRY(do_softirq_own_stack) CFI_STARTPROC pushq_cfi %rbp CFI_REL_OFFSET rbp,0 mov %rsp,%rbp CFI_DEF_CFA_REGISTER rbp incl PER_CPU_VAR(irq_count) cmove PER_CPU_VAR(irq_stack_ptr),%rsp push %rbp # backlink for old unwinder call __do_softirq leaveq CFI_RESTORE rbp CFI_DEF_CFA_REGISTER rsp CFI_ADJUST_CFA_OFFSET -8 decl PER_CPU_VAR(irq_count) ret CFI_ENDPROC END(do_softirq_own_stack) #ifdef CONFIG_XEN idtentry xen_hypervisor_callback xen_do_hypervisor_callback has_error_code=0 /* * A note on the "critical region" in our callback handler. * We want to avoid stacking callback handlers due to events occurring * during handling of the last event. To do this, we keep events disabled * until we've done all processing. HOWEVER, we must enable events before * popping the stack frame (can't be done atomically) and so it would still * be possible to get enough handler activations to overflow the stack. * Although unlikely, bugs of that kind are hard to track down, so we'd * like to avoid the possibility. * So, on entry to the handler we detect whether we interrupted an * existing activation in its critical region -- if so, we pop the current * activation and restart the handler using the previous one. */ ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs) CFI_STARTPROC /* * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will * see the correct pointer to the pt_regs */ movq %rdi, %rsp # we don't return, adjust the stack frame CFI_ENDPROC DEFAULT_FRAME 11: incl PER_CPU_VAR(irq_count) movq %rsp,%rbp CFI_DEF_CFA_REGISTER rbp cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp pushq %rbp # backlink for old unwinder call xen_evtchn_do_upcall popq %rsp CFI_DEF_CFA_REGISTER rsp decl PER_CPU_VAR(irq_count) #ifndef CONFIG_PREEMPT call xen_maybe_preempt_hcall #endif jmp error_exit CFI_ENDPROC END(xen_do_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 do not need to fix up as Xen has already reloaded all segment * registers that could be reloaded and zeroed the others. * Category 2 we fix up by killing the current process. 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 comparing each saved segment register * with its current contents: any discrepancy means we in category 1. */ ENTRY(xen_failsafe_callback) INTR_FRAME 1 (6*8) /*CFI_REL_OFFSET gs,GS*/ /*CFI_REL_OFFSET fs,FS*/ /*CFI_REL_OFFSET es,ES*/ /*CFI_REL_OFFSET ds,DS*/ CFI_REL_OFFSET r11,8 CFI_REL_OFFSET rcx,0 movw %ds,%cx cmpw %cx,0x10(%rsp) CFI_REMEMBER_STATE jne 1f movw %es,%cx cmpw %cx,0x18(%rsp) jne 1f movw %fs,%cx cmpw %cx,0x20(%rsp) jne 1f movw %gs,%cx cmpw %cx,0x28(%rsp) jne 1f /* All segments match their saved values => Category 2 (Bad IRET). */ movq (%rsp),%rcx CFI_RESTORE rcx movq 8(%rsp),%r11 CFI_RESTORE r11 addq $0x30,%rsp CFI_ADJUST_CFA_OFFSET -0x30 pushq_cfi $0 /* RIP */ pushq_cfi %r11 pushq_cfi %rcx jmp general_protection CFI_RESTORE_STATE 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */ movq (%rsp),%rcx CFI_RESTORE rcx movq 8(%rsp),%r11 CFI_RESTORE r11 addq $0x30,%rsp CFI_ADJUST_CFA_OFFSET -0x30 pushq_cfi $-1 /* orig_ax = -1 => not a system call */ ALLOC_PT_GPREGS_ON_STACK SAVE_C_REGS SAVE_EXTRA_REGS jmp error_exit CFI_ENDPROC END(xen_failsafe_callback) apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ xen_hvm_callback_vector xen_evtchn_do_upcall #endif /* CONFIG_XEN */ #if IS_ENABLED(CONFIG_HYPERV) apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ hyperv_callback_vector hyperv_vector_handler #endif /* CONFIG_HYPERV */ idtentry debug do_debug has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK idtentry int3 do_int3 has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK idtentry stack_segment do_stack_segment has_error_code=1 #ifdef CONFIG_XEN idtentry xen_debug do_debug has_error_code=0 idtentry xen_int3 do_int3 has_error_code=0 idtentry xen_stack_segment do_stack_segment has_error_code=1 #endif idtentry general_protection do_general_protection has_error_code=1 trace_idtentry page_fault do_page_fault has_error_code=1 #ifdef CONFIG_KVM_GUEST idtentry async_page_fault do_async_page_fault has_error_code=1 #endif #ifdef CONFIG_X86_MCE idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vector(%rip) #endif /* * Save all registers in pt_regs, and switch gs if needed. * Use slow, but surefire "are we in kernel?" check. * Return: ebx=0: need swapgs on exit, ebx=1: otherwise */ ENTRY(paranoid_entry) XCPT_FRAME 1 15*8 cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 movl $1,%ebx movl $MSR_GS_BASE,%ecx rdmsr testl %edx,%edx js 1f /* negative -> in kernel */ SWAPGS xorl %ebx,%ebx 1: ret CFI_ENDPROC END(paranoid_entry) /* * "Paranoid" exit path from exception stack. This is invoked * only on return from non-NMI IST interrupts that came * from kernel space. * * We may be returning to very strange contexts (e.g. very early * in syscall entry), so checking for preemption here would * be complicated. Fortunately, we there's no good reason * to try to handle preemption here. */ /* On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it) */ ENTRY(paranoid_exit) DEFAULT_FRAME DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF_DEBUG testl %ebx,%ebx /* swapgs needed? */ jnz paranoid_exit_no_swapgs TRACE_IRQS_IRETQ SWAPGS_UNSAFE_STACK jmp paranoid_exit_restore paranoid_exit_no_swapgs: TRACE_IRQS_IRETQ_DEBUG paranoid_exit_restore: RESTORE_EXTRA_REGS RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 INTERRUPT_RETURN CFI_ENDPROC END(paranoid_exit) /* * Save all registers in pt_regs, and switch gs if needed. * Return: ebx=0: need swapgs on exit, ebx=1: otherwise */ ENTRY(error_entry) XCPT_FRAME 1 15*8 cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 xorl %ebx,%ebx testl $3,CS+8(%rsp) je error_kernelspace error_swapgs: SWAPGS error_sti: TRACE_IRQS_OFF ret /* * There are two places in the kernel that can potentially fault with * usergs. Handle them here. B stepping K8s sometimes report a * truncated RIP for IRET exceptions returning to compat mode. Check * for these here too. */ error_kernelspace: CFI_REL_OFFSET rcx, RCX+8 incl %ebx leaq native_irq_return_iret(%rip),%rcx cmpq %rcx,RIP+8(%rsp) je error_bad_iret movl %ecx,%eax /* zero extend */ cmpq %rax,RIP+8(%rsp) je bstep_iret cmpq $gs_change,RIP+8(%rsp) je error_swapgs jmp error_sti bstep_iret: /* Fix truncated RIP */ movq %rcx,RIP+8(%rsp) /* fall through */ error_bad_iret: SWAPGS mov %rsp,%rdi call fixup_bad_iret mov %rax,%rsp decl %ebx /* Return to usergs */ jmp error_sti CFI_ENDPROC END(error_entry) /* On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it) */ ENTRY(error_exit) DEFAULT_FRAME movl %ebx,%eax RESTORE_EXTRA_REGS DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF GET_THREAD_INFO(%rcx) testl %eax,%eax jne retint_kernel LOCKDEP_SYS_EXIT_IRQ movl TI_flags(%rcx),%edx movl $_TIF_WORK_MASK,%edi andl %edi,%edx jnz retint_careful jmp retint_swapgs CFI_ENDPROC END(error_exit) /* * Test if a given stack is an NMI stack or not. */ .macro test_in_nmi reg stack nmi_ret normal_ret cmpq %\reg, \stack ja \normal_ret subq $EXCEPTION_STKSZ, %\reg cmpq %\reg, \stack jb \normal_ret jmp \nmi_ret .endm /* runs on exception stack */ ENTRY(nmi) INTR_FRAME PARAVIRT_ADJUST_EXCEPTION_FRAME /* * We allow breakpoints in NMIs. If a breakpoint occurs, then * the iretq it performs will take us out of NMI context. * This means that we can have nested NMIs where the next * NMI is using the top of the stack of the previous NMI. We * can't let it execute because the nested NMI will corrupt the * stack of the previous NMI. NMI handlers are not re-entrant * anyway. * * To handle this case we do the following: * Check the a special location on the stack that contains * a variable that is set when NMIs are executing. * The interrupted task's stack is also checked to see if it * is an NMI stack. * If the variable is not set and the stack is not the NMI * stack then: * o Set the special variable on the stack * o Copy the interrupt frame into a "saved" location on the stack * o Copy the interrupt frame into a "copy" location on the stack * o Continue processing the NMI * If the variable is set or the previous stack is the NMI stack: * o Modify the "copy" location to jump to the repeate_nmi * o return back to the first NMI * * Now on exit of the first NMI, we first clear the stack variable * The NMI stack will tell any nested NMIs at that point that it is * nested. Then we pop the stack normally with iret, and if there was * a nested NMI that updated the copy interrupt stack frame, a * jump will be made to the repeat_nmi code that will handle the second * NMI. */ /* Use %rdx as out temp variable throughout */ pushq_cfi %rdx CFI_REL_OFFSET rdx, 0 /* * If %cs was not the kernel segment, then the NMI triggered in user * space, which means it is definitely not nested. */ cmpl $__KERNEL_CS, 16(%rsp) jne first_nmi /* * Check the special variable on the stack to see if NMIs are * executing. */ cmpl $1, -8(%rsp) je nested_nmi /* * Now test if the previous stack was an NMI stack. * We need the double check. We check the NMI stack to satisfy the * race when the first NMI clears the variable before returning. * We check the variable because the first NMI could be in a * breakpoint routine using a breakpoint stack. */ lea 6*8(%rsp), %rdx test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi CFI_REMEMBER_STATE nested_nmi: /* * Do nothing if we interrupted the fixup in repeat_nmi. * It's about to repeat the NMI handler, so we are fine * with ignoring this one. */ movq $repeat_nmi, %rdx cmpq 8(%rsp), %rdx ja 1f movq $end_repeat_nmi, %rdx cmpq 8(%rsp), %rdx ja nested_nmi_out 1: /* Set up the interrupted NMIs stack to jump to repeat_nmi */ leaq -1*8(%rsp), %rdx movq %rdx, %rsp CFI_ADJUST_CFA_OFFSET 1*8 leaq -10*8(%rsp), %rdx pushq_cfi $__KERNEL_DS pushq_cfi %rdx pushfq_cfi pushq_cfi $__KERNEL_CS pushq_cfi $repeat_nmi /* Put stack back */ addq $(6*8), %rsp CFI_ADJUST_CFA_OFFSET -6*8 nested_nmi_out: popq_cfi %rdx CFI_RESTORE rdx /* No need to check faults here */ INTERRUPT_RETURN CFI_RESTORE_STATE first_nmi: /* * Because nested NMIs will use the pushed location that we * stored in rdx, we must keep that space available. * Here's what our stack frame will look like: * +-------------------------+ * | original SS | * | original Return RSP | * | original RFLAGS | * | original CS | * | original RIP | * +-------------------------+ * | temp storage for rdx | * +-------------------------+ * | NMI executing variable | * +-------------------------+ * | copied SS | * | copied Return RSP | * | copied RFLAGS | * | copied CS | * | copied RIP | * +-------------------------+ * | Saved SS | * | Saved Return RSP | * | Saved RFLAGS | * | Saved CS | * | Saved RIP | * +-------------------------+ * | pt_regs | * +-------------------------+ * * The saved stack frame is used to fix up the copied stack frame * that a nested NMI may change to make the interrupted NMI iret jump * to the repeat_nmi. The original stack frame and the temp storage * is also used by nested NMIs and can not be trusted on exit. */ /* Do not pop rdx, nested NMIs will corrupt that part of the stack */ movq (%rsp), %rdx CFI_RESTORE rdx /* Set the NMI executing variable on the stack. */ pushq_cfi $1 /* * Leave room for the "copied" frame */ subq $(5*8), %rsp CFI_ADJUST_CFA_OFFSET 5*8 /* Copy the stack frame to the Saved frame */ .rept 5 pushq_cfi 11*8(%rsp) .endr CFI_DEF_CFA_OFFSET 5*8 /* Everything up to here is safe from nested NMIs */ /* * If there was a nested NMI, the first NMI's iret will return * here. But NMIs are still enabled and we can take another * nested NMI. The nested NMI checks the interrupted RIP to see * if it is between repeat_nmi and end_repeat_nmi, and if so * it will just return, as we are about to repeat an NMI anyway. * This makes it safe to copy to the stack frame that a nested * NMI will update. */ repeat_nmi: /* * Update the stack variable to say we are still in NMI (the update * is benign for the non-repeat case, where 1 was pushed just above * to this very stack slot). */ movq $1, 10*8(%rsp) /* Make another copy, this one may be modified by nested NMIs */ addq $(10*8), %rsp CFI_ADJUST_CFA_OFFSET -10*8 .rept 5 pushq_cfi -6*8(%rsp) .endr subq $(5*8), %rsp CFI_DEF_CFA_OFFSET 5*8 end_repeat_nmi: /* * Everything below this point can be preempted by a nested * NMI if the first NMI took an exception and reset our iret stack * so that we repeat another NMI. */ pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */ ALLOC_PT_GPREGS_ON_STACK /* * Use paranoid_entry to handle SWAPGS, but no need to use paranoid_exit * as we should not be calling schedule in NMI context. * Even with normal interrupts enabled. An NMI should not be * setting NEED_RESCHED or anything that normal interrupts and * exceptions might do. */ call paranoid_entry DEFAULT_FRAME 0 /* * Save off the CR2 register. If we take a page fault in the NMI then * it could corrupt the CR2 value. If the NMI preempts a page fault * handler before it was able to read the CR2 register, and then the * NMI itself takes a page fault, the page fault that was preempted * will read the information from the NMI page fault and not the * origin fault. Save it off and restore it if it changes. * Use the r12 callee-saved register. */ movq %cr2, %r12 /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ movq %rsp,%rdi movq $-1,%rsi call do_nmi /* Did the NMI take a page fault? Restore cr2 if it did */ movq %cr2, %rcx cmpq %rcx, %r12 je 1f movq %r12, %cr2 1: testl %ebx,%ebx /* swapgs needed? */ jnz nmi_restore nmi_swapgs: SWAPGS_UNSAFE_STACK nmi_restore: RESTORE_EXTRA_REGS RESTORE_C_REGS /* Pop the extra iret frame at once */ REMOVE_PT_GPREGS_FROM_STACK 6*8 /* Clear the NMI executing stack variable */ movq $0, 5*8(%rsp) jmp irq_return CFI_ENDPROC END(nmi) ENTRY(ignore_sysret) CFI_STARTPROC mov $-ENOSYS,%eax sysret CFI_ENDPROC END(ignore_sysret)