/*
 *  linux/arch/i386/kernel/process.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#define __KERNEL_SYSCALLS__
#include <stdarg.h>

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/malloc.h>
#include <linux/ldt.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/config.h>
#include <linux/unistd.h>
#include <linux/delay.h>

#include <asm/segment.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <linux/smp.h>

asmlinkage void ret_from_sys_call(void) __asm__("ret_from_sys_call");

#ifdef CONFIG_APM
extern int  apm_do_idle(void);
extern void apm_do_busy(void);
#endif

static int hlt_counter=0;

#define HARD_IDLE_TIMEOUT (HZ / 3)

void disable_hlt(void)
{
	hlt_counter++;
}

void enable_hlt(void)
{
	hlt_counter--;
}

#ifndef __SMP__

static void hard_idle(void)
{
	while (!need_resched) {
		if (hlt_works_ok && !hlt_counter) {
#ifdef CONFIG_APM
				/* If the APM BIOS is not enabled, or there
				 is an error calling the idle routine, we
				 should hlt if possible.  We need to check
				 need_resched again because an interrupt
				 may have occurred in apm_do_idle(). */
			start_bh_atomic();
			if (!apm_do_idle() && !need_resched)
				__asm__("hlt");
			end_bh_atomic();
#else
			__asm__("hlt");
#endif
	        }
 		if (need_resched) 
 			break;
		schedule();
	}
#ifdef CONFIG_APM
	apm_do_busy();
#endif
}

/*
 * The idle loop on a uniprocessor i386..
 */
 
asmlinkage int sys_idle(void)
{
        unsigned long start_idle = 0;

	if (current->pid != 0)
		return -EPERM;
	/* endless idle loop with no priority at all */
	current->counter = -100;
	for (;;) 
	{
		/*
		 *	We are locked at this point. So we can safely call
		 *	the APM bios knowing only one CPU at a time will do
		 *	so.
		 */
		if (!start_idle) 
			start_idle = jiffies;
		if (jiffies - start_idle > HARD_IDLE_TIMEOUT) 
		{
			hard_idle();
		} 
		else 
		{
			if (hlt_works_ok && !hlt_counter && !need_resched)
		        	__asm__("hlt");
		}
		if (need_resched) 
			start_idle = 0;
		schedule();
	}
}

#else

/*
 *	In the SMP world we hlt outside of kernel syscall rather than within
 *	so as to get the right locking semantics.
 */
 
asmlinkage int sys_idle(void)
{
	if(current->pid != 0)
		return -EPERM;
#ifdef __SMP_PROF__
	smp_spins_sys_idle[smp_processor_id()]+=
	  smp_spins_syscall_cur[smp_processor_id()];
#endif
	current->counter= -100;
	schedule();
	return 0;
}

/*
 *	This is being executed in task 0 'user space'.
 */

int cpu_idle(void *unused)
{
	while(1)
	{
		if(cpu_data[smp_processor_id()].hlt_works_ok && !hlt_counter && !need_resched)
			__asm("hlt");
                if(0==(0x7fffffff & smp_process_available)) 
                	continue;
                while(0x80000000 & smp_process_available);
	        cli();
                while(set_bit(31,&smp_process_available))
                	while(test_bit(31,&smp_process_available))
                {
                	/*
                	 *	Oops.. This is kind of important in some cases...
                	 */
                	if(clear_bit(smp_processor_id(), &smp_invalidate_needed))
                		local_flush_tlb();
                }
                if (0==(0x7fffffff & smp_process_available)){
                        clear_bit(31,&smp_process_available);
                        sti();
                        continue;
                }
                smp_process_available--;
                clear_bit(31,&smp_process_available);
                sti();
		idle();
	}
}

#endif

/*
 * This routine reboots the machine by asking the keyboard
 * controller to pulse the reset-line low. We try that for a while,
 * and if it doesn't work, we do some other stupid things.
 */
static long no_idt[2] = {0, 0};
static int reboot_mode = 0;

void reboot_setup(char *str, int *ints)
{
	int mode = 0;

	/* "w" for "warm" reboot (no memory testing etc) */
	if (str[0] == 'w')
		mode = 0x1234;
	reboot_mode = mode;
}

static inline void kb_wait(void)
{
	int i;

	for (i=0; i<0x10000; i++)
		if ((inb_p(0x64) & 0x02) == 0)
			break;
}

void hard_reset_now(void)
{
	int i, j;

	sti();
/* rebooting needs to touch the page at absolute addr 0 */
	pg0[0] = 7;
	*((unsigned short *)0x472) = reboot_mode;
	for (;;) {
		for (i=0; i<100; i++) {
			kb_wait();
			for(j = 0; j < 100000 ; j++)
				/* nothing */;
			outb(0xfe,0x64);	 /* pulse reset low */
			udelay(10);
		}
		__asm__ __volatile__("\tlidt %0": "=m" (no_idt));
	}
}

void show_regs(struct pt_regs * regs)
{
	printk("\n");
	printk("EIP: %04x:[<%08lx>]",0xffff & regs->cs,regs->eip);
	if (regs->cs & 3)
		printk(" ESP: %04x:%08lx",0xffff & regs->ss,regs->esp);
	printk(" EFLAGS: %08lx\n",regs->eflags);
	printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
		regs->eax,regs->ebx,regs->ecx,regs->edx);
	printk("ESI: %08lx EDI: %08lx EBP: %08lx",
		regs->esi, regs->edi, regs->ebp);
	printk(" DS: %04x ES: %04x FS: %04x GS: %04x\n",
		0xffff & regs->ds,0xffff & regs->es,
		0xffff & regs->fs,0xffff & regs->gs);
}

/*
 * Free current thread data structures etc..
 */

void exit_thread(void)
{
	/* forget lazy i387 state */
	if (last_task_used_math == current)
		last_task_used_math = NULL;
	/* forget local segments */
	__asm__ __volatile__("mov %w0,%%fs ; mov %w0,%%gs ; lldt %w0"
		: /* no outputs */
		: "r" (0));
	current->tss.ldt = 0;
	if (current->ldt) {
		void * ldt = current->ldt;
		current->ldt = NULL;
		vfree(ldt);
	}
}

void flush_thread(void)
{
	int i;

	if (current->ldt) {
		free_page((unsigned long) current->ldt);
		current->ldt = NULL;
		for (i=1 ; i<NR_TASKS ; i++) {
			if (task[i] == current)  {
				set_ldt_desc(gdt+(i<<1)+
					     FIRST_LDT_ENTRY,&default_ldt, 1);
				load_ldt(i);
			}
		}	
	}

	for (i=0 ; i<8 ; i++)
		current->debugreg[i] = 0;

	/*
	 * Forget coprocessor state..
	 */
#ifdef __SMP__
	if (current->flags & PF_USEDFPU) {
		stts();
	}
#else
	if (last_task_used_math == current) {
		last_task_used_math = NULL;
		stts();
	}
#endif
	current->used_math = 0;
	current->flags &= ~PF_USEDFPU;
}

void release_thread(struct task_struct *dead_task)
{
}

void copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
	struct task_struct * p, struct pt_regs * regs)
{
	int i;
	struct pt_regs * childregs;

	p->tss.es = KERNEL_DS;
	p->tss.cs = KERNEL_CS;
	p->tss.ss = KERNEL_DS;
	p->tss.ds = KERNEL_DS;
	p->tss.fs = USER_DS;
	p->tss.gs = KERNEL_DS;
	p->tss.ss0 = KERNEL_DS;
	p->tss.esp0 = p->kernel_stack_page + PAGE_SIZE;
	p->tss.tr = _TSS(nr);
	childregs = ((struct pt_regs *) (p->kernel_stack_page + PAGE_SIZE)) - 1;
	p->tss.esp = (unsigned long) childregs;
	p->tss.eip = (unsigned long) ret_from_sys_call;
	*childregs = *regs;
	childregs->eax = 0;
	childregs->esp = esp;
	p->tss.back_link = 0;
	p->tss.eflags = regs->eflags & 0xffffcfff;	/* iopl is always 0 for a new process */
	p->tss.ldt = _LDT(nr);
	if (p->ldt) {
		p->ldt = (struct desc_struct*) vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE);
		if (p->ldt != NULL)
			memcpy(p->ldt, current->ldt, LDT_ENTRIES*LDT_ENTRY_SIZE);
	}
	set_tss_desc(gdt+(nr<<1)+FIRST_TSS_ENTRY,&(p->tss));
	if (p->ldt)
		set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,p->ldt, 512);
	else
		set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,&default_ldt, 1);
	p->tss.bitmap = offsetof(struct thread_struct,io_bitmap);
	for (i = 0; i < IO_BITMAP_SIZE+1 ; i++) /* IO bitmap is actually SIZE+1 */
		p->tss.io_bitmap[i] = ~0;
	if (last_task_used_math == current)
		__asm__("clts ; fnsave %0 ; frstor %0":"=m" (p->tss.i387));
}

/*
 * fill in the fpu structure for a core dump..
 */
int dump_fpu (struct pt_regs * regs, struct user_i387_struct* fpu)
{
	int fpvalid;

/* Flag indicating the math stuff is valid. We don't support this for the
   soft-float routines yet */
	if (hard_math) {
		if ((fpvalid = current->used_math) != 0) {
			if (last_task_used_math == current)
				__asm__("clts ; fnsave %0": :"m" (*fpu));
			else
				memcpy(fpu,&current->tss.i387.hard,sizeof(*fpu));
		}
	} else {
		/* we should dump the emulator state here, but we need to
		   convert it into standard 387 format first.. */
		fpvalid = 0;
	}

	return fpvalid;
}

/*
 * fill in the user structure for a core dump..
 */
void dump_thread(struct pt_regs * regs, struct user * dump)
{
	int i;

/* changed the size calculations - should hopefully work better. lbt */
	dump->magic = CMAGIC;
	dump->start_code = 0;
	dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
	dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
	dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
	dump->u_dsize -= dump->u_tsize;
	dump->u_ssize = 0;
	for (i = 0; i < 8; i++)
		dump->u_debugreg[i] = current->debugreg[i];  

	if (dump->start_stack < TASK_SIZE)
		dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;

	dump->regs = *regs;

	dump->u_fpvalid = dump_fpu (regs, &dump->i387);
}

asmlinkage int sys_fork(struct pt_regs regs)
{
	return do_fork(SIGCHLD, regs.esp, &regs);
}

asmlinkage int sys_clone(struct pt_regs regs)
{
	unsigned long clone_flags;
	unsigned long newsp;

	clone_flags = regs.ebx;
	newsp = regs.ecx;
	if (!newsp)
		newsp = regs.esp;
	return do_fork(clone_flags, newsp, &regs);
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(struct pt_regs regs)
{
	int error;
	char * filename;

	error = getname((char *) regs.ebx, &filename);
	if (error)
		return error;
	error = do_execve(filename, (char **) regs.ecx, (char **) regs.edx, &regs);
	putname(filename);
	return error;
}
