path: root/arch/i386/kernel/entry.S

/*
 *  linux/arch/i386/entry.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 'ret_from_system_call':
 * 	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) - orig_eax
 *	28(%esp) - %eip
 *	2C(%esp) - %cs
 *	30(%esp) - %eflags
 *	34(%esp) - %oldesp
 *	38(%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/dwarf2.h>
#include "irq_vectors.h"

#define nr_syscalls ((syscall_table_size)/4)

EBX		= 0x00
ECX		= 0x04
EDX		= 0x08
ESI		= 0x0C
EDI		= 0x10
EBP		= 0x14
EAX		= 0x18
DS		= 0x1C
ES		= 0x20
ORIG_EAX	= 0x24
EIP		= 0x28
CS		= 0x2C
EFLAGS		= 0x30
OLDESP		= 0x34
OLDSS		= 0x38

CF_MASK		= 0x00000001
TF_MASK		= 0x00000100
IF_MASK		= 0x00000200
DF_MASK		= 0x00000400 
NT_MASK		= 0x00004000
VM_MASK		= 0x00020000

/* These are replaces for paravirtualization */
#define DISABLE_INTERRUPTS		cli
#define ENABLE_INTERRUPTS		sti
#define ENABLE_INTERRUPTS_SYSEXIT	sti; sysexit
#define INTERRUPT_RETURN		iret
#define GET_CR0_INTO_EAX		movl %cr0, %eax

#ifdef CONFIG_PREEMPT
#define preempt_stop		DISABLE_INTERRUPTS; TRACE_IRQS_OFF
#else
#define preempt_stop
#define resume_kernel		restore_nocheck
#endif

.macro TRACE_IRQS_IRET
#ifdef CONFIG_TRACE_IRQFLAGS
	testl $IF_MASK,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 %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;

#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;\
	/*CFI_RESTORE ds;*/\
2:	popl %es;	\
	CFI_ADJUST_CFA_OFFSET -4;\
	/*CFI_RESTORE es;*/\
.section .fixup,"ax";	\
3:	movl $0,(%esp);	\
	jmp 1b;		\
4:	movl $0,(%esp);	\
	jmp 2b;		\
.previous;		\
.section __ex_table,"a";\
	.align 4;	\
	.long 1b,3b;	\
	.long 2b,4b;	\
.previous

#define 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

#define 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

#define RING0_PTREGS_FRAME \
	CFI_STARTPROC simple;\
	CFI_SIGNAL_FRAME;\
	CFI_DEF_CFA esp, OLDESP-EBX;\
	/*CFI_OFFSET cs, CS-OLDESP;*/\
	CFI_OFFSET eip, EIP-OLDESP;\
	/*CFI_OFFSET es, ES-OLDESP;*/\
	/*CFI_OFFSET ds, DS-OLDESP;*/\
	CFI_OFFSET eax, EAX-OLDESP;\
	CFI_OFFSET ebp, EBP-OLDESP;\
	CFI_OFFSET edi, EDI-OLDESP;\
	CFI_OFFSET esi, ESI-OLDESP;\
	CFI_OFFSET edx, EDX-OLDESP;\
	CFI_OFFSET ecx, ECX-OLDESP;\
	CFI_OFFSET ebx, EBX-OLDESP

ENTRY(ret_from_fork)
	CFI_STARTPROC
	pushl %eax
	CFI_ADJUST_CFA_OFFSET 4
	call schedule_tail
	GET_THREAD_INFO(%ebp)
	popl %eax
	CFI_ADJUST_CFA_OFFSET -4
	pushl $0x0202			# Reset kernel eflags
	CFI_ADJUST_CFA_OFFSET 4
	popfl