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Diffstat (limited to 'arch/x86/kernel/entry_32.S')
| -rw-r--r-- | arch/x86/kernel/entry_32.S | 1401 |
1 files changed, 1401 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S new file mode 100644 index 000000000..1c309763e --- /dev/null +++ b/arch/x86/kernel/entry_32.S @@ -0,0 +1,1401 @@ +/* + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +/* + * entry.S contains the system-call and fault low-level handling routines. + * This also contains the timer-interrupt handler, as well as all interrupts + * and faults that can result in a task-switch. + * + * NOTE: This code handles signal-recognition, which happens every time + * after a timer-interrupt and after each system call. + * + * I changed all the .align's to 4 (16 byte alignment), as that's faster + * on a 486. + * + * Stack layout in 'syscall_exit': + * ptrace needs to have all regs on the stack. + * if the order here is changed, it needs to be + * updated in fork.c:copy_process, signal.c:do_signal, + * ptrace.c and ptrace.h + * + * 0(%esp) - %ebx + * 4(%esp) - %ecx + * 8(%esp) - %edx + * C(%esp) - %esi + * 10(%esp) - %edi + * 14(%esp) - %ebp + * 18(%esp) - %eax + * 1C(%esp) - %ds + * 20(%esp) - %es + * 24(%esp) - %fs + * 28(%esp) - %gs saved iff !CONFIG_X86_32_LAZY_GS + * 2C(%esp) - orig_eax + * 30(%esp) - %eip + * 34(%esp) - %cs + * 38(%esp) - %eflags + * 3C(%esp) - %oldesp + * 40(%esp) - %oldss + * + * "current" is in register %ebx during any slow entries. + */ + +#include <linux/linkage.h> +#include <linux/err.h> +#include <asm/thread_info.h> +#include <asm/irqflags.h> +#include <asm/errno.h> +#include <asm/segment.h> +#include <asm/smp.h> +#include <asm/page_types.h> +#include <asm/percpu.h> +#include <asm/dwarf2.h> +#include <asm/processor-flags.h> +#include <asm/ftrace.h> +#include <asm/irq_vectors.h> +#include <asm/cpufeature.h> +#include <asm/alternative-asm.h> +#include <asm/asm.h> +#include <asm/smap.h> + +/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ +#include <linux/elf-em.h> +#define AUDIT_ARCH_I386 (EM_386|__AUDIT_ARCH_LE) +#define __AUDIT_ARCH_LE 0x40000000 + +#ifndef CONFIG_AUDITSYSCALL +#define sysenter_audit syscall_trace_entry +#define sysexit_audit syscall_exit_work +#endif + + .section .entry.text, "ax" + +/* + * We use macros for low-level operations which need to be overridden + * for paravirtualization. The following will never clobber any registers: + * INTERRUPT_RETURN (aka. "iret") + * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax") + * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit"). + * + * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must + * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY). + * Allowing a register to be clobbered can shrink the paravirt replacement + * enough to patch inline, increasing performance. + */ + +#ifdef CONFIG_PREEMPT +#define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF +#else +#define preempt_stop(clobbers) +#define resume_kernel restore_all +#endif + +.macro TRACE_IRQS_IRET +#ifdef CONFIG_TRACE_IRQFLAGS + testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off? + jz 1f + TRACE_IRQS_ON +1: +#endif +.endm + +/* + * User gs save/restore + * + * %gs is used for userland TLS and kernel only uses it for stack + * canary which is required to be at %gs:20 by gcc. Read the comment + * at the top of stackprotector.h for more info. + * + * Local labels 98 and 99 are used. + */ +#ifdef CONFIG_X86_32_LAZY_GS + + /* unfortunately push/pop can't be no-op */ +.macro PUSH_GS + pushl_cfi $0 +.endm +.macro POP_GS pop=0 + addl $(4 + \pop), %esp + CFI_ADJUST_CFA_OFFSET -(4 + \pop) +.endm +.macro POP_GS_EX +.endm + + /* all the rest are no-op */ +.macro PTGS_TO_GS +.endm +.macro PTGS_TO_GS_EX +.endm +.macro GS_TO_REG reg +.endm +.macro REG_TO_PTGS reg +.endm +.macro SET_KERNEL_GS reg +.endm + +#else /* CONFIG_X86_32_LAZY_GS */ + +.macro PUSH_GS + pushl_cfi %gs + /*CFI_REL_OFFSET gs, 0*/ +.endm + +.macro POP_GS pop=0 +98: popl_cfi %gs + /*CFI_RESTORE gs*/ + .if \pop <> 0 + add $\pop, %esp + CFI_ADJUST_CFA_OFFSET -\pop + .endif +.endm +.macro POP_GS_EX +.pushsection .fixup, "ax" +99: movl $0, (%esp) + jmp 98b +.popsection + _ASM_EXTABLE(98b,99b) +.endm + +.macro PTGS_TO_GS +98: mov PT_GS(%esp), %gs +.endm +.macro PTGS_TO_GS_EX +.pushsection .fixup, "ax" +99: movl $0, PT_GS(%esp) + jmp 98b +.popsection + _ASM_EXTABLE(98b,99b) +.endm + +.macro GS_TO_REG reg + movl %gs, \reg + /*CFI_REGISTER gs, \reg*/ +.endm +.macro REG_TO_PTGS reg + movl \reg, PT_GS(%esp) + /*CFI_REL_OFFSET gs, PT_GS*/ +.endm +.macro SET_KERNEL_GS reg + movl $(__KERNEL_STACK_CANARY), \reg + movl \reg, %gs +.endm + +#endif /* CONFIG_X86_32_LAZY_GS */ + +.macro SAVE_ALL + cld + PUSH_GS + pushl_cfi %fs + /*CFI_REL_OFFSET fs, 0;*/ + pushl_cfi %es + /*CFI_REL_OFFSET es, 0;*/ + pushl_cfi %ds + /*CFI_REL_OFFSET ds, 0;*/ + pushl_cfi %eax + CFI_REL_OFFSET eax, 0 + pushl_cfi %ebp + CFI_REL_OFFSET ebp, 0 + pushl_cfi %edi + CFI_REL_OFFSET edi, 0 + pushl_cfi %esi + CFI_REL_OFFSET esi, 0 + pushl_cfi %edx + CFI_REL_OFFSET edx, 0 + pushl_cfi %ecx + CFI_REL_OFFSET ecx, 0 + pushl_cfi %ebx + CFI_REL_OFFSET ebx, 0 + movl $(__USER_DS), %edx + movl %edx, %ds + movl %edx, %es + movl $(__KERNEL_PERCPU), %edx + movl %edx, %fs + SET_KERNEL_GS %edx +.endm + +.macro RESTORE_INT_REGS + popl_cfi %ebx + CFI_RESTORE ebx + popl_cfi %ecx + CFI_RESTORE ecx + popl_cfi %edx + CFI_RESTORE edx + popl_cfi %esi + CFI_RESTORE esi + popl_cfi %edi + CFI_RESTORE edi + popl_cfi %ebp + CFI_RESTORE ebp + popl_cfi %eax + CFI_RESTORE eax +.endm + +.macro RESTORE_REGS pop=0 + RESTORE_INT_REGS +1: popl_cfi %ds + /*CFI_RESTORE ds;*/ +2: popl_cfi %es + /*CFI_RESTORE es;*/ +3: popl_cfi %fs + /*CFI_RESTORE fs;*/ + POP_GS \pop +.pushsection .fixup, "ax" +4: movl $0, (%esp) + jmp 1b +5: movl $0, (%esp) + jmp 2b +6: movl $0, (%esp) + jmp 3b +.popsection + _ASM_EXTABLE(1b,4b) + _ASM_EXTABLE(2b,5b) + _ASM_EXTABLE(3b,6b) + POP_GS_EX +.endm + +.macro RING0_INT_FRAME + CFI_STARTPROC simple + CFI_SIGNAL_FRAME + CFI_DEF_CFA esp, 3*4 + /*CFI_OFFSET cs, -2*4;*/ + CFI_OFFSET eip, -3*4 +.endm + +.macro RING0_EC_FRAME + CFI_STARTPROC simple + CFI_SIGNAL_FRAME + CFI_DEF_CFA esp, 4*4 + /*CFI_OFFSET cs, -2*4;*/ + CFI_OFFSET eip, -3*4 +.endm + +.macro RING0_PTREGS_FRAME + CFI_STARTPROC simple + CFI_SIGNAL_FRAME + CFI_DEF_CFA esp, PT_OLDESP-PT_EBX + /*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/ + CFI_OFFSET eip, PT_EIP-PT_OLDESP + /*CFI_OFFSET es, PT_ES-PT_OLDESP;*/ + /*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/ + CFI_OFFSET eax, PT_EAX-PT_OLDESP + CFI_OFFSET ebp, PT_EBP-PT_OLDESP + CFI_OFFSET edi, PT_EDI-PT_OLDESP + CFI_OFFSET esi, PT_ESI-PT_OLDESP + CFI_OFFSET edx, PT_EDX-PT_OLDESP + CFI_OFFSET ecx, PT_ECX-PT_OLDESP + CFI_OFFSET ebx, PT_EBX-PT_OLDESP +.endm + +ENTRY(ret_from_fork) + CFI_STARTPROC + pushl_cfi %eax + call schedule_tail + GET_THREAD_INFO(%ebp) + popl_cfi %eax + pushl_cfi $0x0202 # Reset kernel eflags + popfl_cfi + jmp syscall_exit + CFI_ENDPROC +END(ret_from_fork) + +ENTRY(ret_from_kernel_thread) + CFI_STARTPROC + pushl_cfi %eax + call schedule_tail + GET_THREAD_INFO(%ebp) + popl_cfi %eax + pushl_cfi $0x0202 # Reset kernel eflags + popfl_cfi + movl PT_EBP(%esp),%eax + call *PT_EBX(%esp) + movl $0,PT_EAX(%esp) + jmp syscall_exit + CFI_ENDPROC +ENDPROC(ret_from_kernel_thread) + +/* + * Return to user mode is not as complex as all this looks, + * but we want the default path for a system call return to + * go as quickly as possible which is why some of this is + * less clear than it otherwise should be. + */ + + # userspace resumption stub bypassing syscall exit tracing + ALIGN + RING0_PTREGS_FRAME +ret_from_exception: + preempt_stop(CLBR_ANY) +ret_from_intr: + GET_THREAD_INFO(%ebp) +#ifdef CONFIG_VM86 + movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS + movb PT_CS(%esp), %al + andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax +#else + /* + * We can be coming here from child spawned by kernel_thread(). + */ + movl PT_CS(%esp), %eax + andl $SEGMENT_RPL_MASK, %eax +#endif + cmpl $USER_RPL, %eax + jb resume_kernel # not returning to v8086 or userspace + +ENTRY(resume_userspace) + LOCKDEP_SYS_EXIT + DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt + # setting need_resched or sigpending + # between sampling and the iret + TRACE_IRQS_OFF + movl TI_flags(%ebp), %ecx + andl $_TIF_WORK_MASK, %ecx # is there any work to be done on + # int/exception return? + jne work_pending + jmp restore_all +END(ret_from_exception) + +#ifdef CONFIG_PREEMPT +ENTRY(resume_kernel) + DISABLE_INTERRUPTS(CLBR_ANY) +need_resched: + cmpl $0,PER_CPU_VAR(__preempt_count) + jnz restore_all + testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off (exception path) ? + jz restore_all + call preempt_schedule_irq + jmp need_resched +END(resume_kernel) +#endif + CFI_ENDPROC + +/* SYSENTER_RETURN points to after the "sysenter" instruction in + the vsyscall page. See vsyscall-sysentry.S, which defines the symbol. */ + + # sysenter call handler stub +ENTRY(ia32_sysenter_target) + CFI_STARTPROC simple + CFI_SIGNAL_FRAME + CFI_DEF_CFA esp, 0 + CFI_REGISTER esp, ebp + movl TSS_sysenter_sp0(%esp),%esp +sysenter_past_esp: + /* + * Interrupts are disabled here, but we can't trace it until + * enough kernel state to call TRACE_IRQS_OFF can be called - but + * we immediately enable interrupts at that point anyway. + */ + pushl_cfi $__USER_DS + /*CFI_REL_OFFSET ss, 0*/ + pushl_cfi %ebp + CFI_REL_OFFSET esp, 0 + pushfl_cfi + orl $X86_EFLAGS_IF, (%esp) + pushl_cfi $__USER_CS + /*CFI_REL_OFFSET cs, 0*/ + /* + * Push current_thread_info()->sysenter_return to the stack. + * A tiny bit of offset fixup is necessary: TI_sysenter_return + * is relative to thread_info, which is at the bottom of the + * kernel stack page. 4*4 means the 4 words pushed above; + * TOP_OF_KERNEL_STACK_PADDING takes us to the top of the stack; + * and THREAD_SIZE takes us to the bottom. + */ + pushl_cfi ((TI_sysenter_return) - THREAD_SIZE + TOP_OF_KERNEL_STACK_PADDING + 4*4)(%esp) + CFI_REL_OFFSET eip, 0 + + pushl_cfi %eax + SAVE_ALL + ENABLE_INTERRUPTS(CLBR_NONE) + +/* + * Load the potential sixth argument from user stack. + * Careful about security. + */ + cmpl $__PAGE_OFFSET-3,%ebp + jae syscall_fault + ASM_STAC +1: movl (%ebp),%ebp + ASM_CLAC + movl %ebp,PT_EBP(%esp) + _ASM_EXTABLE(1b,syscall_fault) + + GET_THREAD_INFO(%ebp) + + testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp) + jnz sysenter_audit +sysenter_do_call: + cmpl $(NR_syscalls), %eax + jae sysenter_badsys + call *sys_call_table(,%eax,4) +sysenter_after_call: + movl %eax,PT_EAX(%esp) + LOCKDEP_SYS_EXIT + DISABLE_INTERRUPTS(CLBR_ANY) + TRACE_IRQS_OFF + movl TI_flags(%ebp), %ecx + testl $_TIF_ALLWORK_MASK, %ecx + jnz sysexit_audit +sysenter_exit: +/* if something modifies registers it must also disable sysexit */ + movl PT_EIP(%esp), %edx + movl PT_OLDESP(%esp), %ecx + xorl %ebp,%ebp + TRACE_IRQS_ON +1: mov PT_FS(%esp), %fs + PTGS_TO_GS + ENABLE_INTERRUPTS_SYSEXIT + +#ifdef CONFIG_AUDITSYSCALL +sysenter_audit: + testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp) + jnz syscall_trace_entry + /* movl PT_EAX(%esp), %eax already set, syscall number: 1st arg to audit */ + movl PT_EBX(%esp), %edx /* ebx/a0: 2nd arg to audit */ + /* movl PT_ECX(%esp), %ecx already set, a1: 3nd arg to audit */ + pushl_cfi PT_ESI(%esp) /* a3: 5th arg */ + pushl_cfi PT_EDX+4(%esp) /* a2: 4th arg */ + call __audit_syscall_entry + popl_cfi %ecx /* get that remapped edx off the stack */ + popl_cfi %ecx /* get that remapped esi off the stack */ + movl PT_EAX(%esp),%eax /* reload syscall number */ + jmp sysenter_do_call + +sysexit_audit: + testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx + jnz syscall_exit_work + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_ANY) + movl %eax,%edx /* second arg, syscall return value */ + cmpl $-MAX_ERRNO,%eax /* is it an error ? */ + setbe %al /* 1 if so, 0 if not */ + movzbl %al,%eax /* zero-extend that */ + call __audit_syscall_exit + DISABLE_INTERRUPTS(CLBR_ANY) + TRACE_IRQS_OFF + movl TI_flags(%ebp), %ecx + testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %ecx + jnz syscall_exit_work + movl PT_EAX(%esp),%eax /* reload syscall return value */ + jmp sysenter_exit +#endif + + CFI_ENDPROC +.pushsection .fixup,"ax" +2: movl $0,PT_FS(%esp) + jmp 1b +.popsection + _ASM_EXTABLE(1b,2b) + PTGS_TO_GS_EX +ENDPROC(ia32_sysenter_target) + + # system call handler stub +ENTRY(system_call) + RING0_INT_FRAME # can't unwind into user space anyway + ASM_CLAC + pushl_cfi %eax # save orig_eax + SAVE_ALL + GET_THREAD_INFO(%ebp) + # system call tracing in operation / emulation + testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%ebp) + jnz syscall_trace_entry + cmpl $(NR_syscalls), %eax + jae syscall_badsys +syscall_call: + call *sys_call_table(,%eax,4) +syscall_after_call: + movl %eax,PT_EAX(%esp) # store the return value +syscall_exit: + LOCKDEP_SYS_EXIT + DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt + # setting need_resched or sigpending + # between sampling and the iret + TRACE_IRQS_OFF + movl TI_flags(%ebp), %ecx + testl $_TIF_ALLWORK_MASK, %ecx # current->work + jnz syscall_exit_work + +restore_all: + TRACE_IRQS_IRET +restore_all_notrace: +#ifdef CONFIG_X86_ESPFIX32 + movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS + # Warning: PT_OLDSS(%esp) contains the wrong/random values if we + # are returning to the kernel. + # See comments in process.c:copy_thread() for details. + movb PT_OLDSS(%esp), %ah + movb PT_CS(%esp), %al + andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax + cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax + CFI_REMEMBER_STATE + je ldt_ss # returning to user-space with LDT SS +#endif +restore_nocheck: + RESTORE_REGS 4 # skip orig_eax/error_code +irq_return: + INTERRUPT_RETURN +.section .fixup,"ax" +ENTRY(iret_exc) + pushl $0 # no error code + pushl $do_iret_error + jmp error_code +.previous + _ASM_EXTABLE(irq_return,iret_exc) + +#ifdef CONFIG_X86_ESPFIX32 + CFI_RESTORE_STATE +ldt_ss: +#ifdef CONFIG_PARAVIRT + /* + * The kernel can't run on a non-flat stack if paravirt mode + * is active. Rather than try to fixup the high bits of + * ESP, bypass this code entirely. This may break DOSemu + * and/or Wine support in a paravirt VM, although the option + * is still available to implement the setting of the high + * 16-bits in the INTERRUPT_RETURN paravirt-op. + */ + cmpl $0, pv_info+PARAVIRT_enabled + jne restore_nocheck +#endif + +/* + * Setup and switch to ESPFIX stack + * + * We're returning to userspace with a 16 bit stack. The CPU will not + * restore the high word of ESP for us on executing iret... This is an + * "official" bug of all the x86-compatible CPUs, which we can work + * around to make dosemu and wine happy. We do this by preloading the + * high word of ESP with the high word of the userspace ESP while + * compensating for the offset by changing to the ESPFIX segment with + * a base address that matches for the difference. + */ +#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8) + mov %esp, %edx /* load kernel esp */ + mov PT_OLDESP(%esp), %eax /* load userspace esp */ + mov %dx, %ax /* eax: new kernel esp */ + sub %eax, %edx /* offset (low word is 0) */ + shr $16, %edx + mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */ + mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */ + pushl_cfi $__ESPFIX_SS + pushl_cfi %eax /* new kernel esp */ + /* Disable interrupts, but do not irqtrace this section: we + * will soon execute iret and the tracer was already set to + * the irqstate after the iret */ + DISABLE_INTERRUPTS(CLBR_EAX) + lss (%esp), %esp /* switch to espfix segment */ + CFI_ADJUST_CFA_OFFSET -8 + jmp restore_nocheck +#endif + CFI_ENDPROC +ENDPROC(system_call) + + # perform work that needs to be done immediately before resumption + ALIGN + RING0_PTREGS_FRAME # can't unwind into user space anyway +work_pending: + testb $_TIF_NEED_RESCHED, %cl + jz work_notifysig +work_resched: + call schedule + LOCKDEP_SYS_EXIT + DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt + # setting need_resched or sigpending + # between sampling and the iret + TRACE_IRQS_OFF + movl TI_flags(%ebp), %ecx + andl $_TIF_WORK_MASK, %ecx # is there any work to be done other + # than syscall tracing? + jz restore_all + testb $_TIF_NEED_RESCHED, %cl + jnz work_resched + +work_notifysig: # deal with pending signals and + # notify-resume requests +#ifdef CONFIG_VM86 + testl $X86_EFLAGS_VM, PT_EFLAGS(%esp) + movl %esp, %eax + jnz work_notifysig_v86 # returning to kernel-space or + # vm86-space +1: +#else + movl %esp, %eax +#endif + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_NONE) + movb PT_CS(%esp), %bl + andb $SEGMENT_RPL_MASK, %bl + cmpb $USER_RPL, %bl + jb resume_kernel + xorl %edx, %edx + call do_notify_resume + jmp resume_userspace + +#ifdef CONFIG_VM86 + ALIGN +work_notifysig_v86: + pushl_cfi %ecx # save ti_flags for do_notify_resume + call save_v86_state # %eax contains pt_regs pointer + popl_cfi %ecx + movl %eax, %esp + jmp 1b +#endif +END(work_pending) + + # perform syscall exit tracing + ALIGN +syscall_trace_entry: + movl $-ENOSYS,PT_EAX(%esp) + movl %esp, %eax + call syscall_trace_enter + /* What it returned is what we'll actually use. */ + cmpl $(NR_syscalls), %eax + jnae syscall_call + jmp syscall_exit +END(syscall_trace_entry) + + # perform syscall exit tracing + ALIGN +syscall_exit_work: + testl $_TIF_WORK_SYSCALL_EXIT, %ecx + jz work_pending + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_ANY) # could let syscall_trace_leave() call + # schedule() instead + movl %esp, %eax + call syscall_trace_leave + jmp resume_userspace +END(syscall_exit_work) + CFI_ENDPROC + + RING0_INT_FRAME # can't unwind into user space anyway +syscall_fault: + ASM_CLAC + GET_THREAD_INFO(%ebp) + movl $-EFAULT,PT_EAX(%esp) + jmp resume_userspace +END(syscall_fault) + +syscall_badsys: + movl $-ENOSYS,%eax + jmp syscall_after_call +END(syscall_badsys) + +sysenter_badsys: + movl $-ENOSYS,%eax + jmp sysenter_after_call +END(sysenter_badsys) + CFI_ENDPROC + +.macro FIXUP_ESPFIX_STACK +/* + * Switch back for ESPFIX stack to the normal zerobased stack + * + * We can't call C functions using the ESPFIX stack. This code reads + * the high word of the segment base from the GDT and swiches to the + * normal stack and adjusts ESP with the matching offset. + */ +#ifdef CONFIG_X86_ESPFIX32 + /* fixup the stack */ + mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */ + mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */ + shl $16, %eax + addl %esp, %eax /* the adjusted stack pointer */ + pushl_cfi $__KERNEL_DS + pushl_cfi %eax + lss (%esp), %esp /* switch to the normal stack segment */ + CFI_ADJUST_CFA_OFFSET -8 +#endif +.endm +.macro UNWIND_ESPFIX_STACK +#ifdef CONFIG_X86_ESPFIX32 + movl %ss, %eax + /* see if on espfix stack */ + cmpw $__ESPFIX_SS, %ax + jne 27f + movl $__KERNEL_DS, %eax + movl %eax, %ds + movl %eax, %es + /* switch to normal stack */ + FIXUP_ESPFIX_STACK +27: +#endif +.endm + +/* + * Build the entry stubs with some assembler magic. + * We pack 1 stub into every 8-byte block. + */ + .align 8 +ENTRY(irq_entries_start) + RING0_INT_FRAME + vector=FIRST_EXTERNAL_VECTOR + .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR) + pushl_cfi $(~vector+0x80) /* Note: always in signed byte range */ + vector=vector+1 + jmp common_interrupt + CFI_ADJUST_CFA_OFFSET -4 + .align 8 + .endr +END(irq_entries_start) + +/* + * the CPU automatically disables interrupts when executing an IRQ vector, + * so IRQ-flags tracing has to follow that: + */ + .p2align CONFIG_X86_L1_CACHE_SHIFT +common_interrupt: + ASM_CLAC + addl $-0x80,(%esp) /* Adjust vector into the [-256,-1] range */ + SAVE_ALL + TRACE_IRQS_OFF + movl %esp,%eax + call do_IRQ + jmp ret_from_intr +ENDPROC(common_interrupt) + CFI_ENDPROC + +#define BUILD_INTERRUPT3(name, nr, fn) \ +ENTRY(name) \ + RING0_INT_FRAME; \ + ASM_CLAC; \ + pushl_cfi $~(nr); \ + SAVE_ALL; \ + TRACE_IRQS_OFF \ + movl %esp,%eax; \ + call fn; \ + jmp ret_from_intr; \ + CFI_ENDPROC; \ +ENDPROC(name) + + +#ifdef CONFIG_TRACING +#define TRACE_BUILD_INTERRUPT(name, nr) \ + BUILD_INTERRUPT3(trace_##name, nr, smp_trace_##name) +#else +#define TRACE_BUILD_INTERRUPT(name, nr) +#endif + +#define BUILD_INTERRUPT(name, nr) \ + BUILD_INTERRUPT3(name, nr, smp_##name); \ + TRACE_BUILD_INTERRUPT(name, nr) + +/* The include is where all of the SMP etc. interrupts come from */ +#include <asm/entry_arch.h> + +ENTRY(coprocessor_error) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi $do_coprocessor_error + jmp error_code + CFI_ENDPROC +END(coprocessor_error) + +ENTRY(simd_coprocessor_error) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 +#ifdef CONFIG_X86_INVD_BUG + /* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */ + ALTERNATIVE "pushl_cfi $do_general_protection", \ + "pushl $do_simd_coprocessor_error", \ + X86_FEATURE_XMM +#else + pushl_cfi $do_simd_coprocessor_error +#endif + jmp error_code + CFI_ENDPROC +END(simd_coprocessor_error) + +ENTRY(device_not_available) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $-1 # mark this as an int + pushl_cfi $do_device_not_available + jmp error_code + CFI_ENDPROC +END(device_not_available) + +#ifdef CONFIG_PARAVIRT +ENTRY(native_iret) + iret + _ASM_EXTABLE(native_iret, iret_exc) +END(native_iret) + +ENTRY(native_irq_enable_sysexit) + sti + sysexit +END(native_irq_enable_sysexit) +#endif + +ENTRY(overflow) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi $do_overflow + jmp error_code + CFI_ENDPROC +END(overflow) + +ENTRY(bounds) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi $do_bounds + jmp error_code + CFI_ENDPROC +END(bounds) + +ENTRY(invalid_op) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi $do_invalid_op + jmp error_code + CFI_ENDPROC +END(invalid_op) + +ENTRY(coprocessor_segment_overrun) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi $do_coprocessor_segment_overrun + jmp error_code + CFI_ENDPROC +END(coprocessor_segment_overrun) + +ENTRY(invalid_TSS) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $do_invalid_TSS + jmp error_code + CFI_ENDPROC +END(invalid_TSS) + +ENTRY(segment_not_present) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $do_segment_not_present + jmp error_code + CFI_ENDPROC +END(segment_not_present) + +ENTRY(stack_segment) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $do_stack_segment + jmp error_code + CFI_ENDPROC +END(stack_segment) + +ENTRY(alignment_check) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $do_alignment_check + jmp error_code + CFI_ENDPROC +END(alignment_check) + +ENTRY(divide_error) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 # no error code + pushl_cfi $do_divide_error + jmp error_code + CFI_ENDPROC +END(divide_error) + +#ifdef CONFIG_X86_MCE +ENTRY(machine_check) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi machine_check_vector + jmp error_code + CFI_ENDPROC +END(machine_check) +#endif + +ENTRY(spurious_interrupt_bug) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $0 + pushl_cfi $do_spurious_interrupt_bug + jmp error_code + CFI_ENDPROC +END(spurious_interrupt_bug) + +#ifdef CONFIG_XEN +/* Xen doesn't set %esp to be precisely what the normal sysenter + entrypoint expects, so fix it up before using the normal path. */ +ENTRY(xen_sysenter_target) + RING0_INT_FRAME + addl $5*4, %esp /* remove xen-provided frame */ + CFI_ADJUST_CFA_OFFSET -5*4 + jmp sysenter_past_esp + CFI_ENDPROC + +ENTRY(xen_hypervisor_callback) + CFI_STARTPROC + pushl_cfi $-1 /* orig_ax = -1 => not a system call */ + SAVE_ALL + TRACE_IRQS_OFF + + /* Check to see if we got the event in the critical + region in xen_iret_direct, after we've reenabled + events and checked for pending events. This simulates + iret instruction's behaviour where it delivers a + pending interrupt when enabling interrupts. */ + movl PT_EIP(%esp),%eax + cmpl $xen_iret_start_crit,%eax + jb 1f + cmpl $xen_iret_end_crit,%eax + jae 1f + + jmp xen_iret_crit_fixup + +ENTRY(xen_do_upcall) +1: mov %esp, %eax + call xen_evtchn_do_upcall +#ifndef CONFIG_PREEMPT + call xen_maybe_preempt_hcall +#endif + jmp ret_from_intr + CFI_ENDPROC +ENDPROC(xen_hypervisor_callback) + +# Hypervisor uses this for application faults while it executes. +# We get here for two reasons: +# 1. Fault while reloading DS, ES, FS or GS +# 2. Fault while executing IRET +# Category 1 we fix up by reattempting the load, and zeroing the segment +# register if the load fails. +# Category 2 we fix up by jumping to do_iret_error. We cannot use the +# normal Linux return path in this case because if we use the IRET hypercall +# to pop the stack frame we end up in an infinite loop of failsafe callbacks. +# We distinguish between categories by maintaining a status value in EAX. +ENTRY(xen_failsafe_callback) + CFI_STARTPROC + pushl_cfi %eax + movl $1,%eax +1: mov 4(%esp),%ds +2: mov 8(%esp),%es +3: mov 12(%esp),%fs +4: mov 16(%esp),%gs + /* EAX == 0 => Category 1 (Bad segment) + EAX != 0 => Category 2 (Bad IRET) */ + testl %eax,%eax + popl_cfi %eax + lea 16(%esp),%esp + CFI_ADJUST_CFA_OFFSET -16 + jz 5f + jmp iret_exc +5: pushl_cfi $-1 /* orig_ax = -1 => not a system call */ + SAVE_ALL + jmp ret_from_exception + CFI_ENDPROC + +.section .fixup,"ax" +6: xorl %eax,%eax + movl %eax,4(%esp) + jmp 1b +7: xorl %eax,%eax + movl %eax,8(%esp) + jmp 2b +8: xorl %eax,%eax + movl %eax,12(%esp) + jmp 3b +9: xorl %eax,%eax + movl %eax,16(%esp) + jmp 4b +.previous + _ASM_EXTABLE(1b,6b) + _ASM_EXTABLE(2b,7b) + _ASM_EXTABLE(3b,8b) + _ASM_EXTABLE(4b,9b) +ENDPROC(xen_failsafe_callback) + +BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR, + xen_evtchn_do_upcall) + +#endif /* CONFIG_XEN */ + +#if IS_ENABLED(CONFIG_HYPERV) + +BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR, + hyperv_vector_handler) + +#endif /* CONFIG_HYPERV */ + +#ifdef CONFIG_FUNCTION_TRACER +#ifdef CONFIG_DYNAMIC_FTRACE + +ENTRY(mcount) + ret +END(mcount) + +ENTRY(ftrace_caller) + pushl %eax + pushl %ecx + pushl %edx + pushl $0 /* Pass NULL as regs pointer */ + movl 4*4(%esp), %eax + movl 0x4(%ebp), %edx + movl function_trace_op, %ecx + subl $MCOUNT_INSN_SIZE, %eax + +.globl ftrace_call +ftrace_call: + call ftrace_stub + + addl $4,%esp /* skip NULL pointer */ + popl %edx + popl %ecx + popl %eax +ftrace_ret: +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +.globl ftrace_graph_call +ftrace_graph_call: + jmp ftrace_stub +#endif + +.globl ftrace_stub +ftrace_stub: + ret +END(ftrace_caller) + +ENTRY(ftrace_regs_caller) + pushf /* push flags before compare (in cs location) */ + + /* + * i386 does not save SS and ESP when coming from kernel. + * Instead, to get sp, ®s->sp is used (see ptrace.h). + * Unfortunately, that means eflags must be at the same location + * as the current return ip is. We move the return ip into the + * ip location, and move flags into the return ip location. + */ + pushl 4(%esp) /* save return ip into ip slot */ + + pushl $0 /* Load 0 into orig_ax */ + pushl %gs + pushl %fs + pushl %es + pushl %ds + pushl %eax + pushl %ebp + pushl %edi + pushl %esi + pushl %edx + pushl %ecx + pushl %ebx + + movl 13*4(%esp), %eax /* Get the saved flags */ + movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */ + /* clobbering return ip */ + movl $__KERNEL_CS,13*4(%esp) + + movl 12*4(%esp), %eax /* Load ip (1st parameter) */ + subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */ + movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ + movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ + pushl %esp /* Save pt_regs as 4th parameter */ + +GLOBAL(ftrace_regs_call) + call ftrace_stub + + addl $4, %esp /* Skip pt_regs */ + movl 14*4(%esp), %eax /* Move flags back into cs */ + movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */ + movl 12*4(%esp), %eax /* Get return ip from regs->ip */ + movl %eax, 14*4(%esp) /* Put return ip back for ret */ + + popl %ebx + popl %ecx + popl %edx + popl %esi + popl %edi + popl %ebp + popl %eax + popl %ds + popl %es + popl %fs + popl %gs + addl $8, %esp /* Skip orig_ax and ip */ + popf /* Pop flags at end (no addl to corrupt flags) */ + jmp ftrace_ret + + popf + jmp ftrace_stub +#else /* ! CONFIG_DYNAMIC_FTRACE */ + +ENTRY(mcount) + cmpl $__PAGE_OFFSET, %esp + jb ftrace_stub /* Paging not enabled yet? */ + + cmpl $ftrace_stub, ftrace_trace_function + jnz trace +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + cmpl $ftrace_stub, ftrace_graph_return + jnz ftrace_graph_caller + + cmpl $ftrace_graph_entry_stub, ftrace_graph_entry + jnz ftrace_graph_caller +#endif +.globl ftrace_stub +ftrace_stub: + ret + + /* taken from glibc */ +trace: + pushl %eax + pushl %ecx + pushl %edx + movl 0xc(%esp), %eax + movl 0x4(%ebp), %edx + subl $MCOUNT_INSN_SIZE, %eax + + call *ftrace_trace_function + + popl %edx + popl %ecx + popl %eax + jmp ftrace_stub +END(mcount) +#endif /* CONFIG_DYNAMIC_FTRACE */ +#endif /* CONFIG_FUNCTION_TRACER */ + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +ENTRY(ftrace_graph_caller) + pushl %eax + pushl %ecx + pushl %edx + movl 0xc(%esp), %eax + lea 0x4(%ebp), %edx + movl (%ebp), %ecx + subl $MCOUNT_INSN_SIZE, %eax + call prepare_ftrace_return + popl %edx + popl %ecx + popl %eax + ret +END(ftrace_graph_caller) + +.globl return_to_handler +return_to_handler: + pushl %eax + pushl %edx + movl %ebp, %eax + call ftrace_return_to_handler + movl %eax, %ecx + popl %edx + popl %eax + jmp *%ecx +#endif + +#ifdef CONFIG_TRACING +ENTRY(trace_page_fault) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $trace_do_page_fault + jmp error_code + CFI_ENDPROC +END(trace_page_fault) +#endif + +ENTRY(page_fault) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $do_page_fault + ALIGN +error_code: + /* the function address is in %gs's slot on the stack */ + pushl_cfi %fs + /*CFI_REL_OFFSET fs, 0*/ + pushl_cfi %es + /*CFI_REL_OFFSET es, 0*/ + pushl_cfi %ds + /*CFI_REL_OFFSET ds, 0*/ + pushl_cfi_reg eax + pushl_cfi_reg ebp + pushl_cfi_reg edi + pushl_cfi_reg esi + pushl_cfi_reg edx + pushl_cfi_reg ecx + pushl_cfi_reg ebx + cld + movl $(__KERNEL_PERCPU), %ecx + movl %ecx, %fs + UNWIND_ESPFIX_STACK + GS_TO_REG %ecx + movl PT_GS(%esp), %edi # get the function address + movl PT_ORIG_EAX(%esp), %edx # get the error code + movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart + REG_TO_PTGS %ecx + SET_KERNEL_GS %ecx + movl $(__USER_DS), %ecx + movl %ecx, %ds + movl %ecx, %es + TRACE_IRQS_OFF + movl %esp,%eax # pt_regs pointer + call *%edi + jmp ret_from_exception + CFI_ENDPROC +END(page_fault) + +/* + * Debug traps and NMI can happen at the one SYSENTER instruction + * that sets up the real kernel stack. Check here, since we can't + * allow the wrong stack to be used. + * + * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have + * already pushed 3 words if it hits on the sysenter instruction: + * eflags, cs and eip. + * + * We just load the right stack, and push the three (known) values + * by hand onto the new stack - while updating the return eip past + * the instruction that would have done it for sysenter. + */ +.macro FIX_STACK offset ok label + cmpw $__KERNEL_CS, 4(%esp) + jne \ok +\label: + movl TSS_sysenter_sp0 + \offset(%esp), %esp + CFI_DEF_CFA esp, 0 + CFI_UNDEFINED eip + pushfl_cfi + pushl_cfi $__KERNEL_CS + pushl_cfi $sysenter_past_esp + CFI_REL_OFFSET eip, 0 +.endm + +ENTRY(debug) + RING0_INT_FRAME + ASM_CLAC + cmpl $ia32_sysenter_target,(%esp) + jne debug_stack_correct + FIX_STACK 12, debug_stack_correct, debug_esp_fix_insn +debug_stack_correct: + pushl_cfi $-1 # mark this as an int + SAVE_ALL + TRACE_IRQS_OFF + xorl %edx,%edx # error code 0 + movl %esp,%eax # pt_regs pointer + call do_debug + jmp ret_from_exception + CFI_ENDPROC +END(debug) + +/* + * NMI is doubly nasty. It can happen _while_ we're handling + * a debug fault, and the debug fault hasn't yet been able to + * clear up the stack. So we first check whether we got an + * NMI on the sysenter entry path, but after that we need to + * check whether we got an NMI on the debug path where the debug + * fault happened on the sysenter path. + */ +ENTRY(nmi) + RING0_INT_FRAME + ASM_CLAC +#ifdef CONFIG_X86_ESPFIX32 + pushl_cfi %eax + movl %ss, %eax + cmpw $__ESPFIX_SS, %ax + popl_cfi %eax + je nmi_espfix_stack +#endif + cmpl $ia32_sysenter_target,(%esp) + je nmi_stack_fixup + pushl_cfi %eax + movl %esp,%eax + /* Do not access memory above the end of our stack page, + * it might not exist. + */ + andl $(THREAD_SIZE-1),%eax + cmpl $(THREAD_SIZE-20),%eax + popl_cfi %eax + jae nmi_stack_correct + cmpl $ia32_sysenter_target,12(%esp) + je nmi_debug_stack_check +nmi_stack_correct: + /* We have a RING0_INT_FRAME here */ + pushl_cfi %eax + SAVE_ALL + xorl %edx,%edx # zero error code + movl %esp,%eax # pt_regs pointer + call do_nmi + jmp restore_all_notrace + CFI_ENDPROC + +nmi_stack_fixup: + RING0_INT_FRAME + FIX_STACK 12, nmi_stack_correct, 1 + jmp nmi_stack_correct + +nmi_debug_stack_check: + /* We have a RING0_INT_FRAME here */ + cmpw $__KERNEL_CS,16(%esp) + jne nmi_stack_correct + cmpl $debug,(%esp) + jb nmi_stack_correct + cmpl $debug_esp_fix_insn,(%esp) + ja nmi_stack_correct + FIX_STACK 24, nmi_stack_correct, 1 + jmp nmi_stack_correct + +#ifdef CONFIG_X86_ESPFIX32 +nmi_espfix_stack: + /* We have a RING0_INT_FRAME here. + * + * create the pointer to lss back + */ + pushl_cfi %ss + pushl_cfi %esp + addl $4, (%esp) + /* copy the iret frame of 12 bytes */ + .rept 3 + pushl_cfi 16(%esp) + .endr + pushl_cfi %eax + SAVE_ALL + FIXUP_ESPFIX_STACK # %eax == %esp + xorl %edx,%edx # zero error code + call do_nmi + RESTORE_REGS + lss 12+4(%esp), %esp # back to espfix stack + CFI_ADJUST_CFA_OFFSET -24 + jmp irq_return +#endif + CFI_ENDPROC +END(nmi) + +ENTRY(int3) + RING0_INT_FRAME + ASM_CLAC + pushl_cfi $-1 # mark this as an int + SAVE_ALL + TRACE_IRQS_OFF + xorl %edx,%edx # zero error code + movl %esp,%eax # pt_regs pointer + call do_int3 + jmp ret_from_exception + CFI_ENDPROC +END(int3) + +ENTRY(general_protection) + RING0_EC_FRAME + pushl_cfi $do_general_protection + jmp error_code + CFI_ENDPROC +END(general_protection) + +#ifdef CONFIG_KVM_GUEST +ENTRY(async_page_fault) + RING0_EC_FRAME + ASM_CLAC + pushl_cfi $do_async_page_fault + jmp error_code + CFI_ENDPROC +END(async_page_fault) +#endif + |