/* * 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 * * $Id$ */ /* * entry.S contains the system-call and fault low-level handling routines. * * NOTE: This code handles signal-recognition, which happens every time * after an interrupt and after each system call. * * Normal syscalls and interrupts don't save a full stack frame, this is * only done for syscall tracing, signals or fork/exec et.al. * * 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 upto R11. * - full stack frame: Like partial stack frame, but all register saved. * * TODO: * - schedule it carefully for the final hardware. */ #define ASSEMBLY 1 #include #include #include #include #include #include #include #include #include #include #include #include #include #include .code64 #ifndef CONFIG_PREEMPT #define retint_kernel retint_restore_args #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 movq %gs:pda_oldrsp,\tmp movq \tmp,RSP(%rsp) movq $__USER_DS,SS(%rsp) movq $__USER_CS,CS(%rsp) movq $-1,RCX(%rsp) movq R11(%rsp),\tmp /* get eflags */ movq \tmp,EFLAGS(%rsp) .endm .macro RESTORE_TOP_OF_STACK tmp,offset=0 movq RSP-\offset(%rsp),\tmp movq \tmp,%gs:pda_oldrsp movq EFLAGS-\offset(%rsp),\tmp movq \tmp,R11-\offset(%rsp) .endm .macro FAKE_STACK_FRAME child_rip /* push in order ss, rsp, eflags, cs, rip */ xorl %eax, %eax pushq %rax /* ss */ CFI_ADJUST_CFA_OFFSET 8 /*CFI_REL_OFFSET ss,0*/ pushq %rax /* rsp */ CFI_ADJUST_CFA_OFFSET 8 CFI_REL_OFFSET rsp,0 pushq $(1<<9) /* eflags - interrupts on */ CFI_ADJUST_CFA_OFFSET 8 /*CFI_REL_OFFSET rflags,0*/ pushq $__KERNEL_CS /* cs */ CFI_ADJUST_CFA_OFFSET 8 /*CFI_REL_OFFSET cs,0*/ pushq \child_rip /* rip */ CFI_ADJUST_CFA_OFFSET 8 CFI_REL_OFFSET rip,0 pushq %rax /* orig rax */ CFI_ADJUST_CFA_OFFSET 8 .endm .macro UNFAKE_STACK_FRAME addq $8*6, %rsp CFI_ADJUST_CFA_OFFSET -(6*8) .endm .macro CFI_DEFAULT_STACK start=1 .if \start CFI_STARTPROC simple CFI_DEF_CFA rsp,SS+8 .else CFI_DEF_CFA_OFFSET SS+8 .endif CFI_REL_OFFSET r15,R15 CFI_REL_OFFSET r14,R14 CFI_REL_OFFSET r13,R13 CFI_REL_OFFSET r12,R12 CFI_REL_OFFSET rbp,RBP CFI_REL_OFFSET rbx,RBX CFI_REL_OFFSET r11,R11 CFI_REL_OFFSET r10,R10 CFI_REL_OFFSET r9,R9 CFI_REL_OFFSET r8,R8 CFI_REL_OFFSET rax,RAX CFI_REL_OFFSET rcx,RCX CFI_REL_OFFSET rdx,RDX CFI_REL_OFFSET rsi,RSI CFI_REL_OFFSET rdi,RDI CFI_REL_OFFSET rip,RIP /*CFI_REL_OFFSET cs,CS*/ /*CFI_REL_OFFSET rflags,EFLAGS*/ CFI_REL_OFFSET rsp,RSP /*CFI_REL_OFFSET ss,SS*/ .endm /* * A newly forked process directly context switches into this. */ /* rdi: prev */ ENTRY(ret_from_fork) CFI_DEFAULT_STACK call schedule_tail GET_THREAD_INFO(%rcx) testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%rcx) jnz rff_trace rff_action: RESTORE_REST testl $3,CS-ARGOFFSET(%rsp) # from kernel_thread? je int_ret_from_sys_call testl $_TIF_IA32,threadinfo_flags(%rcx) jnz int_ret_from_sys_call RESTORE_TOP_OF_STACK %rdi,ARGOFFSET jmp ret_from_sys_call rff_trace: movq %rsp,%rdi call syscall_trace_leave GET_THREAD_INFO(%rcx) jmp rff_action CFI_ENDPROC /* * System call entry. Upto 6 arguments in registers are supported. * * SYSCALL does not save anything on the stack and does not change the * stack pointer. */ /* * Register setup: * rax system call number * rdi arg0 * rcx return address for syscall/sysret, C arg3 * rsi arg1 * rdx arg2 * r10 arg3 (--> moved to rcx for C) * r8 arg4 * r9 arg5 * r11 eflags for syscall/sysret, temporary for C * r12-r15,rbp,rbx saved by C code, not touched. * * 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. */ ENTRY(system_call) CFI_STARTPROC simple CFI_DEF_CFA rsp,0 CFI_REGISTER rip,rcx /*CFI_REGISTER rflags,r11*/ swapgs movq %rsp,%gs:pda_oldrsp movq %gs:pda_kernelstack,%rsp sti SAVE_ARGS 8,1 movq %rax,ORIG_RAX-ARGOFFSET(%rsp) movq %rcx,RIP-ARGOFFSET(%rsp) CFI_REL_OFFSET rip,RIP-ARGOFFSET GET_THREAD_INFO(%rcx) testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%rcx) CFI_REMEMBER_STATE jnz tracesys cmpq $__NR_syscall_max,%rax ja badsys movq %r10,%rcx call *sys_call_table(,%rax,8) # XXX: rip relative movq %rax,RAX-ARGOFFSET(%rsp) /* * Syscall return path ending with SYSRET (fast path) * Has incomplete stack frame and undefined top of stack. */ .globl ret_from_sys_call ret_from_sys_call: movl $_TIF_ALLWORK_MASK,%edi /* edi: flagmask */ sysret_check: GET_THREAD_INFO(%rcx) cli movl threadinfo_flags(%rcx),%edx andl %edi,%edx CFI_REMEMBER_STATE jnz sysret_careful movq RIP-ARGOFFSET(%rsp),%rcx CFI_REGISTER rip,rcx RESTORE_ARGS 0,-ARG_SKIP,1 /*CFI_REGISTER rflags,r11*/ movq %gs:pda_oldrsp,%rsp swapgs sysretq /* Handle reschedules */ /* edx: work, edi: workmask */ sysret_careful: CFI_RESTORE_STATE bt $TIF_NEED_RESCHED,%edx jnc sysret_signal sti pushq %rdi CFI_ADJUST_CFA_OFFSET 8 call schedule popq %rdi CFI_ADJUST_CFA_OFFSET -8 jmp sysret_check /* Handle a signal */ sysret_signal: sti testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx jz 1f /* Really a signal */ /* edx: work flags (arg3) */ leaq do_notify_resume(%rip),%rax leaq -ARGOFFSET(%rsp),%rdi # &pt_regs -> arg1 xorl %esi,%esi # oldset -> arg2 call ptregscall_common 1: movl $_TIF_NEED_RESCHED,%edi jmp sysret_check badsys: movq $-ENOSYS,RAX-ARGOFFSET(%rsp) jmp ret_from_sys_call /* Do syscall tracing */ tracesys: CFI_RESTORE_STATE SAVE_REST movq $-ENOSYS,RAX(%rsp) FIXUP_TOP_OF_STACK %rdi movq %rsp,%rdi call syscall_trace_enter LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */ RESTORE_REST cmpq $__NR_syscall_max,%rax ja 1f movq %r10,%rcx /* fixup for C */ call *sys_call_table(,%rax,8) movq %rax,RAX-ARGOFFSET(%rsp) 1: SAVE_REST movq %rsp,%rdi call syscall_trace_leave RESTORE_TOP_OF_STACK %rbx RESTORE_REST jmp ret_from_sys_call CFI_ENDPROC /* * Syscall return path ending with IRET. * Has correct top of stack, but partial stack frame. */ ENTRY(int_ret_from_sys_call) CFI_STARTPROC simple CFI_DEF_CFA rsp,SS+8-ARGOFFSET /*CFI_REL_OFFSET ss,SS-ARGOFFSET*/ CFI_REL_OFFSET rsp,RSP-ARGOFFSET /*CFI_REL_OFFSET rflags,EFLAGS-ARGOFFSET*/ /*CFI_REL_OFFSET cs,CS-ARGOFFSET*/ CFI_REL_OFFSET rip,RIP-ARGOFFSET CFI_REL_OFFSET rdx,RDX-ARGOFFSET CFI_REL_OFFSET rcx,RCX-ARGOFFSET CFI_REL_OFFSET rax,RAX-ARGOFFSET CFI_REL_OFFSET rdi,RDI-ARGOFFSET CFI_REL_OFFSET rsi,RSI-ARGOFFSET CFI_REL_OFFSET r8,R8-ARGOFFSET CFI_REL_OFFSET r9,R9-ARGOFFSET CFI_REL_OFFSET r10,R10-ARGOFFSET CFI_REL_OFFSET r11,R11-ARGOFFSET cli testl $3,CS-ARGOFFSET(%rsp) je retint_restore_args movl $_TIF_ALLWORK_MASK,%edi /* edi: mask to check */ int_with_check: GET_THREAD_INFO(%rcx) movl threadinfo_flags(%rcx),%edx andl %edi,%edx jnz int_careful andl $~TS_COMPAT,threadinfo_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 sti pushq %rdi CFI_ADJUST_CFA_OFFSET 8 call schedule popq %rdi CFI_ADJUST_CFA_OFFSET -8 cli jmp int_with_check /* handle signals and tracing -- both require a full stack frame */ int_very_careful: sti SAVE_REST /* Check for syscall exit trace */ testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edx jz int_signal pushq %rdi CFI_ADJUST_CFA_OFFSET 8 leaq 8(%rsp),%rdi # &ptregs -> arg1 call syscall_trace_leave popq %rdi CFI_ADJUST_CFA_OFFSET -8 andl $~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edi cli jmp int_restore_rest int_signal: testl $(_TIF_NOTIFY_RESUME|_TIF_SIGPENDING|_TIF_SINGLESTEP),%edx jz 1f movq %rsp,%rdi # &ptregs -> arg1 xorl %esi,%esi # oldset -> arg2 call do_notify_resume 1: movl $_TIF_NEED_RESCHED,%edi int_restore_rest: RESTORE_REST cli jmp int_with_check CFI_ENDPROC /* * Certain special system calls that need to save a complete full stack frame. */ .macro PTREGSCALL label,func,arg .globl \label \label: leaq \func(%rip),%rax leaq -ARGOFFSET+8(%rsp),\arg /* 8 for return address */ jmp ptregscall_common .endm CFI_STARTPROC PTREGSCALL stub_clone, sys_clone, %r8 PTREGSCALL stub_fork, sys_fork, %rdi PTREGSCALL stub_vfork, sys_vfork, %rdi PTREGSCALL stub_rt_sigsuspend, sys_rt_sigsuspend, %rdx PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx PTREGSCALL stub_iopl, sys_iopl, %rsi ENTRY(ptregscall_common) popq %r11 CFI_ADJUST_CFA_OFFSET -8 CFI_REGISTER rip, r11 SAVE_REST movq %r11, %r15 CFI_REGISTER rip, r15 FIXUP_TOP_OF_STACK %r11 call *%rax RESTORE_TOP_OF_STACK %r11 movq %r15, %r11 CFI_REGISTER rip, r11 RESTORE_REST pushq %r11 CFI_ADJUST_CFA_OFFSET 8 CFI_REL_OFFSET rip, 0 ret CFI_ENDPROC ENTRY(stub_execve) CFI_STARTPROC popq %r11 CFI_ADJUST_CFA_OFFSET -8 CFI_REGISTER rip, r11 SAVE_REST FIXUP_TOP_OF_STACK %r11 call sys_execve RESTORE_TOP_OF_STACK %r11 movq %rax,RAX(%rsp) RESTORE_REST jmp int_ret_from_sys_call CFI_ENDPROC /* * 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 CFI_ADJUST_CFA_OFFSET -8 SAVE_REST movq %rsp,%rdi FIXUP_TOP_OF_STACK %r11 call sys_rt_sigreturn movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer RESTORE_REST jmp int_ret_from_sys_call CFI_ENDPROC /* * initial frame state for interrupts and exceptions */ .macro _frame ref CFI_STARTPROC simple CFI_DEF_CFA rsp,SS+8-\ref /*CFI_REL_OFFSET ss,SS-\ref*/ CFI_REL_OFFSET rsp,RSP-\ref /*CFI_REL_OFFSET rflags,EFLAGS-\ref*/ /*CFI_REL_OFFSET cs,CS-\ref*/ CFI_REL_OFFSET rip,RIP-\ref .endm /* initial frame state for interrupts (and exceptions without error code) */ #define INTR_FRAME _frame RIP /* initial frame state for exceptions with error code (and interrupts with vector already pushed) */ #define XCPT_FRAME _frame ORIG_RAX /* * 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 #ifdef CONFIG_DEBUG_INFO SAVE_ALL movq %rsp,%rdi /* * Setup a stack frame pointer. This allows gdb to trace * back to the original stack. */ movq %rsp,%rbp CFI_DEF_CFA_REGISTER rbp #else SAVE_ARGS leaq -ARGOFFSET(%rsp),%rdi # arg1 for handler #endif testl $3,CS(%rdi) je 1f swapgs 1: incl %gs:pda_irqcount # RED-PEN should check preempt count movq %gs:pda_irqstackptr,%rax cmoveq %rax,%rsp /*todo This needs CFI annotation! */ pushq %rdi # save old stack #ifndef CONFIG_DEBUG_INFO CFI_ADJUST_CFA_OFFSET 8 #endif call \func .endm ENTRY(common_interrupt) XCPT_FRAME interrupt do_IRQ /* 0(%rsp): oldrsp-ARGOFFSET */ ret_from_intr: popq %rdi #ifndef CONFIG_DEBUG_INFO CFI_ADJUST_CFA_OFFSET -8 #endif cli decl %gs:pda_irqcount #ifdef CONFIG_DEBUG_INFO movq RBP(%rdi),%rbp CFI_DEF_CFA_REGISTER rsp #endif leaq ARGOFFSET(%rdi),%rsp /*todo This needs CFI annotation! */ exit_intr: GET_THREAD_INFO(%rcx) testl $3,CS-ARGOFFSET(%rsp) je retint_kernel /* Interrupt came from user space */ /* * Has a correct top of stack, but a partial stack frame * %rcx: thread info. Interrupts off. */ retint_with_reschedule: movl $_TIF_WORK_MASK,%edi retint_check: movl threadinfo_flags(%rcx),%edx andl %edi,%edx CFI_REMEMBER_STATE jnz retint_careful retint_swapgs: swapgs retint_restore_args: cli RESTORE_ARGS 0,8,0 iret_label: iretq .section __ex_table,"a" .quad iret_label,bad_iret .previous .section .fixup,"ax" /* force a signal here? this matches i386 behaviour */ /* running with kernel gs */ bad_iret: movq $11,%rdi /* SIGSEGV */ sti jmp do_exit .previous /* edi: workmask, edx: work */ retint_careful: CFI_RESTORE_STATE bt $TIF_NEED_RESCHED,%edx jnc retint_signal sti pushq %rdi CFI_ADJUST_CFA_OFFSET 8 call schedule popq %rdi CFI_ADJUST_CFA_OFFSET -8 GET_THREAD_INFO(%rcx) cli jmp retint_check retint_signal: testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx jz retint_swapgs sti SAVE_REST movq $-1,ORIG_RAX(%rsp) xorl %esi,%esi # oldset movq %rsp,%rdi # &pt_regs call do_notify_resume RESTORE_REST cli movl $_TIF_NEED_RESCHED,%edi GET_THREAD_INFO(%rcx) jmp retint_check #ifdef CONFIG_PREEMPT /* Returning to kernel space. Check if we need preemption */ /* rcx: threadinfo. interrupts off. */ .p2align retint_kernel: cmpl $0,threadinfo_preempt_count(%rcx) jnz retint_restore_args bt $TIF_NEED_RESCHED,threadinfo_flags(%rcx) jnc retint_restore_args bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */ jnc retint_restore_args call preempt_schedule_irq jmp exit_intr #endif CFI_ENDPROC /* * APIC interrupts. */ .macro apicinterrupt num,func INTR_FRAME pushq $\num-256 CFI_ADJUST_CFA_OFFSET 8 interrupt \func jmp ret_from_intr CFI_ENDPROC .endm ENTRY(thermal_interrupt) apicinterrupt THERMAL_APIC_VECTOR,smp_thermal_interrupt ENTRY(threshold_interrupt) apicinterrupt THRESHOLD_APIC_VECTOR,mce_threshold_interrupt #ifdef CONFIG_SMP ENTRY(reschedule_interrupt) apicinterrupt RESCHEDULE_VECTOR,smp_reschedule_interrupt .macro INVALIDATE_ENTRY num ENTRY(invalidate_interrupt\num) apicinterrupt INVALIDATE_TLB_VECTOR_START+\num,smp_invalidate_interrupt .endm INVALIDATE_ENTRY 0 INVALIDATE_ENTRY 1 INVALIDATE_ENTRY 2 INVALIDATE_ENTRY 3 INVALIDATE_ENTRY 4 INVALIDATE_ENTRY 5 INVALIDATE_ENTRY 6 INVALIDATE_ENTRY 7 ENTRY(call_function_interrupt) apicinterrupt CALL_FUNCTION_VECTOR,smp_call_function_interrupt #endif #ifdef CONFIG_X86_LOCAL_APIC ENTRY(apic_timer_interrupt) apicinterrupt LOCAL_TIMER_VECTOR,smp_apic_timer_interrupt ENTRY(error_interrupt) apicinterrupt ERROR_APIC_VECTOR,smp_error_interrupt ENTRY(spurious_interrupt) apicinterrupt SPURIOUS_APIC_VECTOR,smp_spurious_interrupt #endif /* * Exception entry points. */ .macro zeroentry sym INTR_FRAME pushq $0 /* push error code/oldrax */ CFI_ADJUST_CFA_OFFSET 8 pushq %rax /* push real oldrax to the rdi slot */ CFI_ADJUST_CFA_OFFSET 8 leaq \sym(%rip),%rax jmp error_entry CFI_ENDPROC .endm .macro errorentry sym XCPT_FRAME pushq %rax CFI_ADJUST_CFA_OFFSET 8 leaq \sym(%rip),%rax jmp error_entry CFI_ENDPROC .endm /* error code is on the stack already */ /* handle NMI like exceptions that can happen everywhere */ .macro paranoidentry sym, ist=0 SAVE_ALL cld movl $1,%ebx movl $MSR_GS_BASE,%ecx rdmsr testl %edx,%edx js 1f swapgs xorl %ebx,%ebx 1: .if \ist movq %gs:pda_data_offset, %rbp .endif movq %rsp,%rdi movq ORIG_RAX(%rsp),%rsi movq $-1,ORIG_RAX(%rsp) .if \ist subq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp) .endif call \sym .if \ist addq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp) .endif cli .endm /* * Exception entry point. This expects an error code/orig_rax on the stack * and the exception handler in %rax. */ ENTRY(error_entry) _frame RDI /* rdi slot contains rax, oldrax contains error code */ cld subq $14*8,%rsp CFI_ADJUST_CFA_OFFSET (14*8) movq %rsi,13*8(%rsp) CFI_REL_OFFSET rsi,RSI movq 14*8(%rsp),%rsi /* load rax from rdi slot */ movq %rdx,12*8(%rsp) CFI_REL_OFFSET rdx,RDX movq %rcx,11*8(%rsp) CFI_REL_OFFSET rcx,RCX movq %rsi,10*8(%rsp) /* store rax */ CFI_REL_OFFSET rax,RAX movq %r8, 9*8(%rsp) CFI_REL_OFFSET r8,R8 movq %r9, 8*8(%rsp) CFI_REL_OFFSET r9,R9 movq %r10,7*8(%rsp) CFI_REL_OFFSET r10,R10 movq %r11,6*8(%rsp) CFI_REL_OFFSET r11,R11 movq %rbx,5*8(%rsp) CFI_REL_OFFSET rbx,RBX movq %rbp,4*8(%rsp) CFI_REL_OFFSET rbp,RBP movq %r12,3*8(%rsp) CFI_REL_OFFSET r12,R12 movq %r13,2*8(%rsp) CFI_REL_OFFSET r13,R13 movq %r14,1*8(%rsp) CFI_REL_OFFSET r14,R14 movq %r15,(%rsp) CFI_REL_OFFSET r15,R15 xorl %ebx,%ebx testl $3,CS(%rsp) je error_kernelspace error_swapgs: swapgs error_sti: movq %rdi,RDI(%rsp) movq %rsp,%rdi movq ORIG_RAX(%rsp),%rsi /* get error code */ movq $-1,ORIG_RAX(%rsp) call *%rax /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */ error_exit: movl %ebx,%eax RESTORE_REST cli GET_THREAD_INFO(%rcx) testl %eax,%eax jne retint_kernel movl threadinfo_flags(%rcx),%edx movl $_TIF_WORK_MASK,%edi andl %edi,%edx jnz retint_careful swapgs RESTORE_ARGS 0,8,0 jmp iret_label CFI_ENDPROC error_kernelspace: incl %ebx /* There are two places in the kernel that can potentially fault with usergs. Handle them here. The exception handlers after iret run with kernel gs again, so don't set the user space flag. B stepping K8s sometimes report an truncated RIP for IRET exceptions returning to compat mode. Check for these here too. */ leaq iret_label(%rip),%rbp cmpq %rbp,RIP(%rsp) je error_swapgs movl %ebp,%ebp /* zero extend */ cmpq %rbp,RIP(%rsp) je error_swapgs cmpq $gs_change,RIP(%rsp) je error_swapgs jmp error_sti /* Reload gs selector with exception handling */ /* edi: new selector */ ENTRY(load_gs_index) CFI_STARTPROC pushf CFI_ADJUST_CFA_OFFSET 8 cli swapgs gs_change: movl %edi,%gs 2: mfence /* workaround */ swapgs popf CFI_ADJUST_CFA_OFFSET -8 ret CFI_ENDPROC .section __ex_table,"a" .align 8 .quad gs_change,bad_gs .previous .section .fixup,"ax" /* running with kernelgs */ bad_gs: swapgs /* switch back to user gs */ xorl %eax,%eax movl %eax,%gs jmp 2b .previous /* * Create a kernel thread. * * C extern interface: * extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) * * asm input arguments: * rdi: fn, rsi: arg, rdx: flags */ ENTRY(kernel_thread) CFI_STARTPROC FAKE_STACK_FRAME $child_rip SAVE_ALL # rdi: flags, rsi: usp, rdx: will be &pt_regs movq %rdx,%rdi orq kernel_thread_flags(%rip),%rdi movq $-1, %rsi movq %rsp, %rdx xorl %r8d,%r8d xorl %r9d,%r9d # clone now call do_fork movq %rax,RAX(%rsp) xorl %edi,%edi /* * It isn't worth to check for reschedule here, * so internally to the x86_64 port you can rely on kernel_thread() * not to reschedule the child before returning, this avoids the need * of hacks for example to fork off the per-CPU idle tasks. * [Hopefully no generic code relies on the reschedule -AK] */ RESTORE_ALL UNFAKE_STACK_FRAME ret CFI_ENDPROC child_rip: /* * Here we are in the child and the registers are set as they were * at kernel_thread() invocation in the parent. */ movq %rdi, %rax movq %rsi, %rdi call *%rax # exit xorl %edi, %edi call do_exit /* * execve(). This function needs to use IRET, not SYSRET, to set up all state properly. * * C extern interface: * extern long execve(char *name, char **argv, char **envp) * * asm input arguments: * rdi: name, rsi: argv, rdx: envp * * We want to fallback into: * extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs regs) * * do_sys_execve asm fallback arguments: * rdi: name, rsi: argv, rdx: envp, fake frame on the stack */ ENTRY(execve) CFI_STARTPROC FAKE_STACK_FRAME $0 SAVE_ALL call sys_execve movq %rax, RAX(%rsp) RESTORE_REST testq %rax,%rax je int_ret_from_sys_call RESTORE_ARGS UNFAKE_STACK_FRAME ret CFI_ENDPROC KPROBE_ENTRY(page_fault) errorentry do_page_fault .previous .text ENTRY(coprocessor_error) zeroentry do_coprocessor_error ENTRY(simd_coprocessor_error) zeroentry do_simd_coprocessor_error ENTRY(device_not_available) zeroentry math_state_restore /* runs on exception stack */ KPROBE_ENTRY(debug) INTR_FRAME pushq $0 CFI_ADJUST_CFA_OFFSET 8 paranoidentry do_debug, DEBUG_STACK jmp paranoid_exit CFI_ENDPROC .previous .text /* runs on exception stack */ KPROBE_ENTRY(nmi) INTR_FRAME pushq $-1 CFI_ADJUST_CFA_OFFSET 8 paranoidentry do_nmi /* * "Paranoid" exit path from exception stack. * Paranoid because this is used by NMIs and cannot take * any kernel state for granted. * We don't do kernel preemption checks here, because only * NMI should be common and it does not enable IRQs and * cannot get reschedule ticks. */ /* ebx: no swapgs flag */ paranoid_exit: testl %ebx,%ebx /* swapgs needed? */ jnz paranoid_restore testl $3,CS(%rsp) jnz paranoid_userspace paranoid_swapgs: swapgs paranoid_restore: RESTORE_ALL 8 iretq paranoid_userspace: GET_THREAD_INFO(%rcx) movl threadinfo_flags(%rcx),%ebx andl $_TIF_WORK_MASK,%ebx jz paranoid_swapgs movq %rsp,%rdi /* &pt_regs */ call sync_regs movq %rax,%rsp /* switch stack for scheduling */ testl $_TIF_NEED_RESCHED,%ebx jnz paranoid_schedule movl %ebx,%edx /* arg3: thread flags */ sti xorl %esi,%esi /* arg2: oldset */ movq %rsp,%rdi /* arg1: &pt_regs */ call do_notify_resume cli jmp paranoid_userspace paranoid_schedule: sti call schedule cli jmp paranoid_userspace CFI_ENDPROC .previous .text KPROBE_ENTRY(int3) INTR_FRAME pushq $0 CFI_ADJUST_CFA_OFFSET 8 paranoidentry do_int3, DEBUG_STACK jmp paranoid_exit CFI_ENDPROC .previous .text ENTRY(overflow) zeroentry do_overflow ENTRY(bounds) zeroentry do_bounds ENTRY(invalid_op) zeroentry do_invalid_op ENTRY(coprocessor_segment_overrun) zeroentry do_coprocessor_segment_overrun ENTRY(reserved) zeroentry do_reserved /* runs on exception stack */ ENTRY(double_fault) XCPT_FRAME paranoidentry do_double_fault jmp paranoid_exit CFI_ENDPROC ENTRY(invalid_TSS) errorentry do_invalid_TSS ENTRY(segment_not_present) errorentry do_segment_not_present /* runs on exception stack */ ENTRY(stack_segment) XCPT_FRAME paranoidentry do_stack_segment jmp paranoid_exit CFI_ENDPROC KPROBE_ENTRY(general_protection) errorentry do_general_protection .previous .text ENTRY(alignment_check) errorentry do_alignment_check ENTRY(divide_error) zeroentry do_divide_error ENTRY(spurious_interrupt_bug) zeroentry do_spurious_interrupt_bug #ifdef CONFIG_X86_MCE /* runs on exception stack */ ENTRY(machine_check) INTR_FRAME pushq $0 CFI_ADJUST_CFA_OFFSET 8 paranoidentry do_machine_check jmp paranoid_exit CFI_ENDPROC #endif ENTRY(call_softirq) CFI_STARTPROC movq %gs:pda_irqstackptr,%rax movq %rsp,%rdx CFI_DEF_CFA_REGISTER rdx incl %gs:pda_irqcount cmove %rax,%rsp pushq %rdx /*todo CFI_DEF_CFA_EXPRESSION ...*/ call __do_softirq popq %rsp CFI_DEF_CFA_REGISTER rsp decl %gs:pda_irqcount ret CFI_ENDPROC