path: root/arch/x86/kernel/entry_32.S

/*
 *
 *  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) - orig_eax
 *	2C(%esp) - %eip
 *	30(%esp) - %cs
 *	34(%esp) - %eflags
 *	38(%esp) - %oldesp
 *	3C(%esp) - %oldss
 *
 * "current" is in register %ebx during any slow entries.
 */

#include <linux/linkage.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.h>
#include <asm/desc.h>
#include <asm/percpu.h>
#include <asm/dwarf2.h>
#include <asm/processor-flags.h>
#include <asm/ftrace.h>
#include <asm/irq_vectors.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

/*
 * 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.
 */

#define nr_syscalls ((syscall_table_size)/4)

#ifdef CONFIG_PREEMPT
#define preempt_stop(clobbers)	DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
#else
#define preempt_stop(clobbers)
#define resume_kernel		restore_nocheck
#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

#ifdef CONFIG_VM86
#define resume_userspace_sig	check_userspace
#else
#define resume_userspace_sig	resume_userspace
#endif

#define SAVE_ALL \
	cld; \
	pushl %fs; \
	CFI_ADJUST_CFA_OFFSET 4;\
	/*CFI_REL_OFFSET fs, 0;*/\
	pushl %es; \
	CFI_ADJUST_CFA_OFFSET 4;\
	/*CFI_REL_OFFSET es, 0;*/\
	pushl %ds; \
	CFI_ADJUST_CFA_OFFSET 4;\
	/*CFI_REL_OFFSET ds, 0;*/\
	pushl %eax; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET eax, 0;\
	pushl %ebp; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET ebp, 0;\
	pushl %edi; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET edi, 0;\
	pushl %esi; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET esi, 0;\
	pushl %edx; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET edx, 0;\
	pushl %ecx; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET ecx, 0;\
	pushl %ebx; \
	CFI_ADJUST_CFA_OFFSET 4;\
	CFI_REL_OFFSET ebx, 0;\
	movl $(__USER_DS), %edx; \
	movl %edx, %ds; \
	movl %edx, %es; \
	movl $(__KERNEL_PERCPU), %edx; \
	movl %edx, %fs

#define RESTORE_INT_REGS \
	popl %ebx;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE ebx;\
	popl %ecx;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE ecx;\
	popl %edx;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE edx;\
	popl %esi;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE esi;\
	popl %edi;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE edi;\
	popl %ebp;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE ebp;\
	popl %eax;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	CFI_RESTORE eax

#define RESTORE_REGS	\
	RESTORE_INT_REGS; \
1:	popl %ds;	\
	CFI_ADJUST_CFA_OFFSET -4