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Diffstat (limited to 'arch/x86/kernel/entry_64.S')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 1757 |
1 files changed, 1757 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S new file mode 100644 index 00000000..cdc79b5c --- /dev/null +++ b/arch/x86/kernel/entry_64.S @@ -0,0 +1,1757 @@ +/* + * 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 <pavel@suse.cz> + */ + +/* + * 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. + * + * 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 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. + * - SAVE_ALL/RESTORE_ALL - Save/restore all registers + * - SAVE_ARGS/RESTORE_ARGS - Save/restore registers that C functions modify. + * There are unfortunately lots of special cases where some registers + * not touched. The macro is a big mess that should be cleaned up. + * - SAVE_REST/RESTORE_REST - Handle the registers not saved by SAVE_ARGS. + * Gives a full stack frame. + * - 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. + * - errorentry/paranoidentry/zeroentry - Define exception entry points. + */ + +#include <linux/linkage.h> +#include <asm/segment.h> +#include <asm/cache.h> +#include <asm/errno.h> +#include <asm/dwarf2.h> +#include <asm/calling.h> +#include <asm/asm-offsets.h> +#include <asm/msr.h> +#include <asm/unistd.h> +#include <asm/thread_info.h> +#include <asm/hw_irq.h> +#include <asm/page_types.h> +#include <asm/irqflags.h> +#include <asm/paravirt.h> +#include <asm/ftrace.h> +#include <asm/percpu.h> +#include <linux/err.h> + +/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ +#include <linux/elf-em.h> +#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" + +#ifdef CONFIG_FUNCTION_TRACER +#ifdef CONFIG_DYNAMIC_FTRACE +ENTRY(mcount) + retq +END(mcount) + +ENTRY(ftrace_caller) + cmpl $0, function_trace_stop + jne ftrace_stub + + MCOUNT_SAVE_FRAME + + movq 0x38(%rsp), %rdi + movq 8(%rbp), %rsi + subq $MCOUNT_INSN_SIZE, %rdi + +GLOBAL(ftrace_call) + call ftrace_stub + + MCOUNT_RESTORE_FRAME + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +GLOBAL(ftrace_graph_call) + jmp ftrace_stub +#endif + +GLOBAL(ftrace_stub) + retq +END(ftrace_caller) + +#else /* ! CONFIG_DYNAMIC_FTRACE */ +ENTRY(mcount) + cmpl $0, function_trace_stop + jne ftrace_stub + + cmpq $ftrace_stub, ftrace_trace_function + jnz trace + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + cmpq $ftrace_stub, ftrace_graph_return + jnz ftrace_graph_caller + + cmpq $ftrace_graph_entry_stub, ftrace_graph_entry + jnz ftrace_graph_caller +#endif + +GLOBAL(ftrace_stub) + retq + +trace: + MCOUNT_SAVE_FRAME + + movq 0x38(%rsp), %rdi + movq 8(%rbp), %rsi + subq $MCOUNT_INSN_SIZE, %rdi + + call *ftrace_trace_function + + MCOUNT_RESTORE_FRAME + + jmp ftrace_stub +END(mcount) +#endif /* CONFIG_DYNAMIC_FTRACE */ +#endif /* CONFIG_FUNCTION_TRACER */ + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +ENTRY(ftrace_graph_caller) + cmpl $0, function_trace_stop + jne ftrace_stub + + MCOUNT_SAVE_FRAME + + leaq 8(%rbp), %rdi + movq 0x38(%rsp), %rsi + movq (%rbp), %rdx + subq $MCOUNT_INSN_SIZE, %rsi + + call prepare_ftrace_return + + MCOUNT_RESTORE_FRAME + + retq +END(ftrace_graph_caller) + +GLOBAL(return_to_handler) + subq $24, %rsp + + /* Save the return values */ + movq %rax, (%rsp) + movq %rdx, 8(%rsp) + movq %rbp, %rdi + + call ftrace_return_to_handler + + movq %rax, %rdi + movq 8(%rsp), %rdx + movq (%rsp), %rax + addq $24, %rsp + jmp *%rdi +#endif + + +#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 offset=ARGOFFSET +#ifdef CONFIG_TRACE_IRQFLAGS + bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */ + jnc 1f + TRACE_IRQS_ON +1: +#endif +.endm + +/* + * 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 $-1,RCX+\offset(%rsp) + 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 + + .macro FAKE_STACK_FRAME child_rip + /* push in order ss, rsp, eflags, cs, rip */ + xorl %eax, %eax + pushq_cfi $__KERNEL_DS /* ss */ + /*CFI_REL_OFFSET ss,0*/ + pushq_cfi %rax /* rsp */ + CFI_REL_OFFSET rsp,0 + pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_BIT1) /* eflags - interrupts on */ + /*CFI_REL_OFFSET rflags,0*/ + pushq_cfi $__KERNEL_CS /* cs */ + /*CFI_REL_OFFSET cs,0*/ + pushq_cfi \child_rip /* rip */ + CFI_REL_OFFSET rip,0 + pushq_cfi %rax /* orig rax */ + .endm + + .macro UNFAKE_STACK_FRAME + addq $8*6, %rsp + CFI_ADJUST_CFA_OFFSET -(6*8) + .endm + +/* + * initial frame state for interrupts (and exceptions without error code) + */ + .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, SS+8+\offset-RIP + /*CFI_REL_OFFSET ss, SS+\offset-RIP*/ + CFI_REL_OFFSET rsp, RSP+\offset-RIP + /*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/ + /*CFI_REL_OFFSET cs, CS+\offset-RIP*/ + CFI_REL_OFFSET rip, RIP+\offset-RIP + .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, RIP+\offset-ORIG_RAX + /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/ + .endm + +/* + * frame that enables calling into C. + */ + .macro PARTIAL_FRAME start=1 offset=0 + XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET + CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET + CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET + CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET + CFI_REL_OFFSET rcx, RCX+\offset-ARGOFFSET + CFI_REL_OFFSET rax, RAX+\offset-ARGOFFSET + CFI_REL_OFFSET r8, R8+\offset-ARGOFFSET + CFI_REL_OFFSET r9, R9+\offset-ARGOFFSET + CFI_REL_OFFSET r10, R10+\offset-ARGOFFSET + CFI_REL_OFFSET r11, R11+\offset-ARGOFFSET + .endm + +/* + * frame that enables passing a complete pt_regs to a C function. + */ + .macro DEFAULT_FRAME start=1 offset=0 + PARTIAL_FRAME \start, R11+\offset-R15 + 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 + +/* save partial stack frame */ + .macro SAVE_ARGS_IRQ + cld + /* start from rbp in pt_regs and jump over */ + movq_cfi rdi, RDI-RBP + movq_cfi rsi, RSI-RBP + movq_cfi rdx, RDX-RBP + movq_cfi rcx, RCX-RBP + movq_cfi rax, RAX-RBP + movq_cfi r8, R8-RBP + movq_cfi r9, R9-RBP + movq_cfi r10, R10-RBP + movq_cfi r11, R11-RBP + + /* Save rbp so that we can unwind from get_irq_regs() */ + movq_cfi rbp, 0 + + /* Save previous stack value */ + movq %rsp, %rsi + + leaq -RBP(%rsp),%rdi /* arg1 for handler */ + testl $3, CS-RBP(%rsi) + je 1f + SWAPGS + /* + * 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) + */ +1: incl PER_CPU_VAR(irq_count) + cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp + CFI_DEF_CFA_REGISTER rsi + + /* Store previous stack value */ + pushq %rsi + CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \ + 0x77 /* DW_OP_breg7 */, 0, \ + 0x06 /* DW_OP_deref */, \ + 0x08 /* DW_OP_const1u */, SS+8-RBP, \ + 0x22 /* DW_OP_plus */ + /* We entered an interrupt context - irqs are off: */ + TRACE_IRQS_OFF + .endm + +ENTRY(save_rest) + PARTIAL_FRAME 1 REST_SKIP+8 + movq 5*8+16(%rsp), %r11 /* save return address */ + movq_cfi rbx, RBX+16 + movq_cfi rbp, RBP+16 + movq_cfi r12, R12+16 + movq_cfi r13, R13+16 + movq_cfi r14, R14+16 + movq_cfi r15, R15+16 + movq %r11, 8(%rsp) /* return address */ + FIXUP_TOP_OF_STACK %r11, 16 + ret + CFI_ENDPROC +END(save_rest) + +/* save complete stack frame */ + .pushsection .kprobes.text, "ax" +ENTRY(save_paranoid) + XCPT_FRAME 1 RDI+8 + cld + movq_cfi rdi, RDI+8 + movq_cfi rsi, RSI+8 + movq_cfi rdx, RDX+8 + movq_cfi rcx, RCX+8 + movq_cfi rax, RAX+8 + movq_cfi r8, R8+8 + movq_cfi r9, R9+8 + movq_cfi r10, R10+8 + movq_cfi r11, R11+8 + movq_cfi rbx, RBX+8 + movq_cfi rbp, RBP+8 + movq_cfi r12, R12+8 + movq_cfi r13, R13+8 + movq_cfi r14, R14+8 + movq_cfi r15, R15+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(save_paranoid) + .popsection + +/* + * 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 kernel_eflags(%rip) + popfq_cfi # reset kernel eflags + + call schedule_tail # rdi: 'prev' task parameter + + GET_THREAD_INFO(%rcx) + + RESTORE_REST + + testl $3, CS-ARGOFFSET(%rsp) # from kernel_thread? + jz retint_restore_args + + testl $_TIF_IA32, TI_flags(%rcx) # 32-bit compat task needs IRET + jnz int_ret_from_sys_call + + RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET + jmp ret_from_sys_call # go to the SYSRET fastpath + + CFI_ENDPROC +END(ret_from_fork) + +/* + * System call entry. Up to 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. + * + * 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) + 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) + SAVE_ARGS 8,0 + movq %rax,ORIG_RAX-ARGOFFSET(%rsp) + movq %rcx,RIP-ARGOFFSET(%rsp) + CFI_REL_OFFSET rip,RIP-ARGOFFSET + testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) + 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 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. + */ +ret_from_sys_call: + movl $_TIF_ALLWORK_MASK,%edi + /* edi: flagmask */ +sysret_check: + LOCKDEP_SYS_EXIT + DISABLE_INTERRUPTS(CLBR_NONE) + TRACE_IRQS_OFF + movl TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET),%edx + andl %edi,%edx + jnz sysret_careful + CFI_REMEMBER_STATE + /* + * sysretq will re-enable interrupts: + */ + TRACE_IRQS_ON + movq RIP-ARGOFFSET(%rsp),%rcx + CFI_REGISTER rip,rcx + RESTORE_ARGS 1,-ARG_SKIP,0 + /*CFI_REGISTER rflags,r11*/ + movq PER_CPU_VAR(old_rsp), %rsp + USERGS_SYSRET64 + + CFI_RESTORE_STATE + /* Handle reschedules */ + /* edx: work, edi: workmask */ +sysret_careful: + bt $TIF_NEED_RESCHED,%edx + jnc sysret_signal + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_NONE) + pushq_cfi %rdi + call schedule + popq_cfi %rdi + jmp sysret_check + + /* Handle a signal */ +sysret_signal: + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_NONE) +#ifdef CONFIG_AUDITSYSCALL + bt $TIF_SYSCALL_AUDIT,%edx + jc sysret_audit +#endif + /* + * We have a signal, or exit tracing or single-step. + * These all wind up with the iret return path anyway, + * so just join that path right now. + */ + FIXUP_TOP_OF_STACK %r11, -ARGOFFSET + jmp int_check_syscall_exit_work + +badsys: + movq $-ENOSYS,RAX-ARGOFFSET(%rsp) + jmp ret_from_sys_call + +#ifdef CONFIG_AUDITSYSCALL + /* + * Fast path for syscall audit without full syscall trace. + * We just call __audit_syscall_entry() directly, and then + * jump back to the normal fast path. + */ +auditsys: + movq %r10,%r9 /* 6th arg: 4th syscall arg */ + movq %rdx,%r8 /* 5th arg: 3rd syscall arg */ + movq %rsi,%rcx /* 4th arg: 2nd syscall arg */ + movq %rdi,%rdx /* 3rd arg: 1st syscall arg */ + movq %rax,%rsi /* 2nd arg: syscall number */ + movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */ + call __audit_syscall_entry + LOAD_ARGS 0 /* reload call-clobbered registers */ + jmp system_call_fastpath + + /* + * Return fast path for syscall audit. Call __audit_syscall_exit() + * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT + * masked off. + */ +sysret_audit: + movq RAX-ARGOFFSET(%rsp),%rsi /* second arg, syscall return value */ + cmpq $-MAX_ERRNO,%rsi /* is it < -MAX_ERRNO? */ + setbe %al /* 1 if so, 0 if not */ + movzbl %al,%edi /* zero-extend that into %edi */ + call __audit_syscall_exit + movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi + jmp sysret_check +#endif /* CONFIG_AUDITSYSCALL */ + + /* Do syscall tracing */ +tracesys: +#ifdef CONFIG_AUDITSYSCALL + testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) + jz auditsys +#endif + SAVE_REST + movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */ + FIXUP_TOP_OF_STACK %rdi + movq %rsp,%rdi + call syscall_trace_enter + /* + * Reload arg registers from stack in case ptrace changed them. + * We don't reload %rax because syscall_trace_enter() returned + * the value it wants us to use in the table lookup. + */ + LOAD_ARGS ARGOFFSET, 1 + RESTORE_REST +#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) set to -ENOSYS above */ + movq %r10,%rcx /* fixup for C */ + call *sys_call_table(,%rax,8) + movq %rax,RAX-ARGOFFSET(%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 + call schedule + 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) +int_check_syscall_exit_work: + SAVE_REST + /* 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_REST + DISABLE_INTERRUPTS(CLBR_NONE) + TRACE_IRQS_OFF + jmp int_with_check + CFI_ENDPROC +END(system_call) + +/* + * Certain special system calls that need to save a complete full stack frame. + */ + .macro PTREGSCALL label,func,arg +ENTRY(\label) + PARTIAL_FRAME 1 8 /* offset 8: return address */ + subq $REST_SKIP, %rsp + CFI_ADJUST_CFA_OFFSET REST_SKIP + call save_rest + DEFAULT_FRAME 0 8 /* offset 8: return address */ + leaq 8(%rsp), \arg /* pt_regs pointer */ + call \func + jmp ptregscall_common + CFI_ENDPROC +END(\label) + .endm + + PTREGSCALL stub_clone, sys_clone, %r8 + PTREGSCALL stub_fork, sys_fork, %rdi + PTREGSCALL stub_vfork, sys_vfork, %rdi + PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx + PTREGSCALL stub_iopl, sys_iopl, %rsi + +ENTRY(ptregscall_common) + DEFAULT_FRAME 1 8 /* offset 8: return address */ + RESTORE_TOP_OF_STACK %r11, 8 + movq_cfi_restore R15+8, r15 + movq_cfi_restore R14+8, r14 + movq_cfi_restore R13+8, r13 + movq_cfi_restore R12+8, r12 + movq_cfi_restore RBP+8, rbp + movq_cfi_restore RBX+8, rbx + ret $REST_SKIP /* pop extended registers */ + CFI_ENDPROC +END(ptregscall_common) + +ENTRY(stub_execve) + CFI_STARTPROC + addq $8, %rsp + PARTIAL_FRAME 0 + SAVE_REST + FIXUP_TOP_OF_STACK %r11 + movq %rsp, %rcx + call sys_execve + RESTORE_TOP_OF_STACK %r11 + movq %rax,RAX(%rsp) + RESTORE_REST + jmp int_ret_from_sys_call + CFI_ENDPROC +END(stub_execve) + +/* + * 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 + PARTIAL_FRAME 0 + 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 +END(stub_rt_sigreturn) + +#ifdef CONFIG_X86_X32_ABI + PTREGSCALL stub_x32_sigaltstack, sys32_sigaltstack, %rdx + +ENTRY(stub_x32_rt_sigreturn) + CFI_STARTPROC + addq $8, %rsp + PARTIAL_FRAME 0 + SAVE_REST + movq %rsp,%rdi + FIXUP_TOP_OF_STACK %r11 + call sys32_x32_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 +END(stub_x32_rt_sigreturn) + +ENTRY(stub_x32_execve) + CFI_STARTPROC + addq $8, %rsp + PARTIAL_FRAME 0 + SAVE_REST + FIXUP_TOP_OF_STACK %r11 + movq %rsp, %rcx + call sys32_execve + RESTORE_TOP_OF_STACK %r11 + movq %rax,RAX(%rsp) + RESTORE_REST + jmp int_ret_from_sys_call + CFI_ENDPROC +END(stub_x32_execve) + +#endif + +/* + * 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 (NR_VECTORS-FIRST_EXTERNAL_VECTOR+6)/7 + .balign 32 + .rept 7 + .if vector < NR_VECTORS + .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 + /* reserve pt_regs for scratch regs and rbp */ + subq $ORIG_RAX-RBP, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP + SAVE_ARGS_IRQ + call \func + .endm + +/* + * Interrupt entry/exit should be protected against kprobes + */ + .pushsection .kprobes.text, "ax" + /* + * 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 + addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */ + interrupt do_IRQ + /* 0(%rsp): old_rsp-ARGOFFSET */ +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,SS+8-RBP /* reg/off reset after def_cfa_expr */ + leaq ARGOFFSET-RBP(%rsi), %rsp + CFI_DEF_CFA_REGISTER rsp + CFI_ADJUST_CFA_OFFSET RBP-ARGOFFSET + +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: + 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 + 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_ARGS 1,8,1 + +irq_return: + INTERRUPT_RETURN + + .section __ex_table, "a" + .quad irq_return, bad_iret + .previous + +#ifdef CONFIG_PARAVIRT +ENTRY(native_iret) + iretq + + .section __ex_table,"a" + .quad native_iret, bad_iret + .previous +#endif + + .section .fixup,"ax" +bad_iret: + /* + * The iret traps when the %cs or %ss being restored is bogus. + * We've lost the original trap vector and error code. + * #GPF is the most likely one to get for an invalid selector. + * So pretend we completed the iret and took the #GPF in user mode. + * + * We are now running with the kernel GS after exception recovery. + * But error_entry expects us to have user GS to match the user %cs, + * so swap back. + */ + pushq $0 + + SWAPGS + jmp general_protection + + .previous + + /* 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 + call schedule + 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_REST + movq $-1,ORIG_RAX(%rsp) + xorl %esi,%esi # oldset + movq %rsp,%rdi # &pt_regs + call do_notify_resume + RESTORE_REST + 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,TI_preempt_count(%rcx) + jnz retint_restore_args + bt $TIF_NEED_RESCHED,TI_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 +END(common_interrupt) +/* + * End of kprobes section + */ + .popsection + +/* + * APIC interrupts. + */ +.macro apicinterrupt num sym do_sym +ENTRY(\sym) + INTR_FRAME + pushq_cfi $~(\num) +.Lcommon_\sym: + interrupt \do_sym + jmp ret_from_intr + CFI_ENDPROC +END(\sym) +.endm + +#ifdef CONFIG_SMP +apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \ + irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt +apicinterrupt REBOOT_VECTOR \ + reboot_interrupt smp_reboot_interrupt +#endif + +#ifdef CONFIG_X86_UV +apicinterrupt 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_SMP + ALIGN + INTR_FRAME +.irp idx,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \ + 16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31 +.if NUM_INVALIDATE_TLB_VECTORS > \idx +ENTRY(invalidate_interrupt\idx) + pushq_cfi $~(INVALIDATE_TLB_VECTOR_START+\idx) + jmp .Lcommon_invalidate_interrupt0 + CFI_ADJUST_CFA_OFFSET -8 +END(invalidate_interrupt\idx) +.endif +.endr + CFI_ENDPROC +apicinterrupt INVALIDATE_TLB_VECTOR_START, \ + invalidate_interrupt0, smp_invalidate_interrupt +#endif + +apicinterrupt THRESHOLD_APIC_VECTOR \ + threshold_interrupt smp_threshold_interrupt +apicinterrupt THERMAL_APIC_VECTOR \ + thermal_interrupt smp_thermal_interrupt + +#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. + */ +.macro zeroentry sym do_sym +ENTRY(\sym) + INTR_FRAME + PARAVIRT_ADJUST_EXCEPTION_FRAME + pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */ + subq $ORIG_RAX-R15, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 + call error_entry + DEFAULT_FRAME 0 + movq %rsp,%rdi /* pt_regs pointer */ + xorl %esi,%esi /* no error code */ + call \do_sym + jmp error_exit /* %ebx: no swapgs flag */ + CFI_ENDPROC +END(\sym) +.endm + +.macro paranoidzeroentry sym do_sym +ENTRY(\sym) + INTR_FRAME + PARAVIRT_ADJUST_EXCEPTION_FRAME + pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */ + subq $ORIG_RAX-R15, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 + call save_paranoid + TRACE_IRQS_OFF + movq %rsp,%rdi /* pt_regs pointer */ + xorl %esi,%esi /* no error code */ + call \do_sym + jmp paranoid_exit /* %ebx: no swapgs flag */ + CFI_ENDPROC +END(\sym) +.endm + +#define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8) +.macro paranoidzeroentry_ist sym do_sym ist +ENTRY(\sym) + INTR_FRAME + PARAVIRT_ADJUST_EXCEPTION_FRAME + pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */ + subq $ORIG_RAX-R15, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 + call save_paranoid + TRACE_IRQS_OFF + movq %rsp,%rdi /* pt_regs pointer */ + xorl %esi,%esi /* no error code */ + subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist) + call \do_sym + addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist) + jmp paranoid_exit /* %ebx: no swapgs flag */ + CFI_ENDPROC +END(\sym) +.endm + +.macro errorentry sym do_sym +ENTRY(\sym) + XCPT_FRAME + PARAVIRT_ADJUST_EXCEPTION_FRAME + subq $ORIG_RAX-R15, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 + call error_entry + DEFAULT_FRAME 0 + movq %rsp,%rdi /* pt_regs pointer */ + movq ORIG_RAX(%rsp),%rsi /* get error code */ + movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */ + call \do_sym + jmp error_exit /* %ebx: no swapgs flag */ + CFI_ENDPROC +END(\sym) +.endm + + /* error code is on the stack already */ +.macro paranoiderrorentry sym do_sym +ENTRY(\sym) + XCPT_FRAME + PARAVIRT_ADJUST_EXCEPTION_FRAME + subq $ORIG_RAX-R15, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 + call save_paranoid + DEFAULT_FRAME 0 + TRACE_IRQS_OFF + movq %rsp,%rdi /* pt_regs pointer */ + movq ORIG_RAX(%rsp),%rsi /* get error code */ + movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */ + call \do_sym + jmp paranoid_exit /* %ebx: no swapgs flag */ + CFI_ENDPROC +END(\sym) +.endm + +zeroentry divide_error do_divide_error +zeroentry overflow do_overflow +zeroentry bounds do_bounds +zeroentry invalid_op do_invalid_op +zeroentry device_not_available do_device_not_available +paranoiderrorentry double_fault do_double_fault +zeroentry coprocessor_segment_overrun do_coprocessor_segment_overrun +errorentry invalid_TSS do_invalid_TSS +errorentry segment_not_present do_segment_not_present +zeroentry spurious_interrupt_bug do_spurious_interrupt_bug +zeroentry coprocessor_error do_coprocessor_error +errorentry alignment_check do_alignment_check +zeroentry simd_coprocessor_error do_simd_coprocessor_error + + + /* 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) + + .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 + +ENTRY(kernel_thread_helper) + pushq $0 # fake return address + CFI_STARTPROC + /* + * Here we are in the child and the registers are set as they were + * at kernel_thread() invocation in the parent. + */ + call *%rsi + # exit + mov %eax, %edi + call do_exit + ud2 # padding for call trace + CFI_ENDPROC +END(kernel_thread_helper) + +/* + * execve(). This function needs to use IRET, not SYSRET, to set up all state properly. + * + * C extern interface: + * extern long execve(const char *name, char **argv, char **envp) + * + * asm input arguments: + * rdi: name, rsi: argv, rdx: envp + * + * We want to fallback into: + * extern long sys_execve(const char *name, char **argv,char **envp, struct pt_regs *regs) + * + * do_sys_execve asm fallback arguments: + * rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack + */ +ENTRY(kernel_execve) + CFI_STARTPROC + FAKE_STACK_FRAME $0 + SAVE_ALL + movq %rsp,%rcx + 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 +END(kernel_execve) + +/* Call softirq on interrupt stack. Interrupts are off. */ +ENTRY(call_softirq) + 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(call_softirq) + +#ifdef CONFIG_XEN +zeroentry xen_hypervisor_callback xen_do_hypervisor_callback + +/* + * 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) + 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 $0 + SAVE_ALL + jmp error_exit + CFI_ENDPROC +END(xen_failsafe_callback) + +apicinterrupt XEN_HVM_EVTCHN_CALLBACK \ + xen_hvm_callback_vector xen_evtchn_do_upcall + +#endif /* CONFIG_XEN */ + +/* + * Some functions should be protected against kprobes + */ + .pushsection .kprobes.text, "ax" + +paranoidzeroentry_ist debug do_debug DEBUG_STACK +paranoidzeroentry_ist int3 do_int3 DEBUG_STACK +paranoiderrorentry stack_segment do_stack_segment +#ifdef CONFIG_XEN +zeroentry xen_debug do_debug +zeroentry xen_int3 do_int3 +errorentry xen_stack_segment do_stack_segment +#endif +errorentry general_protection do_general_protection +errorentry page_fault do_page_fault +#ifdef CONFIG_KVM_GUEST +errorentry async_page_fault do_async_page_fault +#endif +#ifdef CONFIG_X86_MCE +paranoidzeroentry machine_check *machine_check_vector(%rip) +#endif + + /* + * "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. + * + * "trace" is 0 for the NMI handler only, because irq-tracing + * is fundamentally NMI-unsafe. (we cannot change the soft and + * hard flags at once, atomically) + */ + + /* ebx: no swapgs flag */ +ENTRY(paranoid_exit) + DEFAULT_FRAME + DISABLE_INTERRUPTS(CLBR_NONE) + TRACE_IRQS_OFF + testl %ebx,%ebx /* swapgs needed? */ + jnz paranoid_restore + testl $3,CS(%rsp) + jnz paranoid_userspace +paranoid_swapgs: + TRACE_IRQS_IRETQ 0 + SWAPGS_UNSAFE_STACK + RESTORE_ALL 8 + jmp irq_return +paranoid_restore: + TRACE_IRQS_IRETQ 0 + RESTORE_ALL 8 + jmp irq_return +paranoid_userspace: + GET_THREAD_INFO(%rcx) + movl TI_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 */ + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_NONE) + xorl %esi,%esi /* arg2: oldset */ + movq %rsp,%rdi /* arg1: &pt_regs */ + call do_notify_resume + DISABLE_INTERRUPTS(CLBR_NONE) + TRACE_IRQS_OFF + jmp paranoid_userspace +paranoid_schedule: + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_ANY) + call schedule + DISABLE_INTERRUPTS(CLBR_ANY) + TRACE_IRQS_OFF + jmp paranoid_userspace + CFI_ENDPROC +END(paranoid_exit) + +/* + * Exception entry point. This expects an error code/orig_rax on the stack. + * returns in "no swapgs flag" in %ebx. + */ +ENTRY(error_entry) + XCPT_FRAME + CFI_ADJUST_CFA_OFFSET 15*8 + /* oldrax contains error code */ + cld + movq_cfi rdi, RDI+8 + movq_cfi rsi, RSI+8 + movq_cfi rdx, RDX+8 + movq_cfi rcx, RCX+8 + movq_cfi rax, RAX+8 + movq_cfi r8, R8+8 + movq_cfi r9, R9+8 + movq_cfi r10, R10+8 + movq_cfi r11, R11+8 + movq_cfi rbx, RBX+8 + movq_cfi rbp, RBP+8 + movq_cfi r12, R12+8 + movq_cfi r13, R13+8 + movq_cfi r14, R14+8 + movq_cfi r15, R15+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. 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. + */ +error_kernelspace: + incl %ebx + leaq irq_return(%rip),%rcx + cmpq %rcx,RIP+8(%rsp) + je error_swapgs + 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) + jmp error_swapgs + CFI_ENDPROC +END(error_entry) + + +/* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */ +ENTRY(error_exit) + DEFAULT_FRAME + movl %ebx,%eax + RESTORE_REST + 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 -6*8(%rsp), %rdx + movq %rdx, %rsp + CFI_ADJUST_CFA_OFFSET 6*8 + pushq_cfi $__KERNEL_DS + pushq_cfi %rdx + pushfq_cfi + pushq_cfi $__KERNEL_CS + pushq_cfi $repeat_nmi + + /* Put stack back */ + addq $(11*8), %rsp + CFI_ADJUST_CFA_OFFSET -11*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 | + * +-------------------------+ + * | Saved SS | + * | Saved Return RSP | + * | Saved RFLAGS | + * | Saved CS | + * | Saved RIP | + * +-------------------------+ + * | copied SS | + * | copied Return RSP | + * | copied RFLAGS | + * | copied CS | + * | copied 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 + + /* Copy the stack frame to the Saved frame */ + .rept 5 + pushq_cfi 6*8(%rsp) + .endr + CFI_DEF_CFA_OFFSET SS+8-RIP + + /* 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, 5*8(%rsp) + + /* Make another copy, this one may be modified by nested NMIs */ + .rept 5 + pushq_cfi 4*8(%rsp) + .endr + CFI_DEF_CFA_OFFSET SS+8-RIP +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 */ + subq $ORIG_RAX-R15, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 + /* + * Use save_paranoid 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 save_paranoid + DEFAULT_FRAME 0 + /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ + movq %rsp,%rdi + movq $-1,%rsi + call do_nmi + testl %ebx,%ebx /* swapgs needed? */ + jnz nmi_restore +nmi_swapgs: + SWAPGS_UNSAFE_STACK +nmi_restore: + RESTORE_ALL 8 + /* Clear the NMI executing stack variable */ + movq $0, 10*8(%rsp) + jmp irq_return + CFI_ENDPROC +END(nmi) + +ENTRY(ignore_sysret) + CFI_STARTPROC + mov $-ENOSYS,%eax + sysret + CFI_ENDPROC +END(ignore_sysret) + +/* + * End of kprobes section + */ + .popsection |