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/*

 *  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;

static int reboot_thru_bios = 0;

void reboot_setup(char *str, int *ints)

{

        while(1) {

                switch (*str) {

                case 'w': /* "warm" reboot (no memory testing etc) */

                        reboot_mode = 0x1234;

                        break;

                case 'c': /* "cold" reboot (with memory testing etc) */

                        reboot_mode = 0x0;

                        break;

                case 'b': /* "bios" reboot by jumping through the BIOS */

                        reboot_thru_bios = 1;

                        break;

                case 'h': /* "hard" reboot by toggling RESET and/or crashing the CPU */

                        reboot_thru_bios = 0;

                        break;

                }

                if((str = strchr(str,',')) != NULL)

                        str++;

                else

                        break;

        }

}

/* The following code and data reboots the machine by switching to real

   mode and jumping to the BIOS reset entry point, as if the CPU has

   really been reset.  The previous version asked the keyboard

   controller to pulse the CPU reset line, which is more thorough, but

   doesn't work with at least one type of 486 motherboard.  It is easy

   to stop this code working; hence the copious comments. */

unsigned long long

real_mode_gdt_entries [3] =

{

        0x0000000000000000ULL,  /* Null descriptor */

        0x00009a000000ffffULL,  /* 16-bit real-mode 64k code at 0x00000000 */

        0x000092000100ffffULL           /* 16-bit real-mode 64k data at 0x00000100 */

};

struct

{

        unsigned short       size __attribute__ ((packed));

        unsigned long long * base __attribute__ ((packed));

}

real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, real_mode_gdt_entries },

real_mode_idt = { 0x3ff, 0 };

/* This is 16-bit protected mode code to disable paging and the cache,

   switch to real mode and jump to the BIOS reset code.

   The instruction that switches to real mode by writing to CR0 must be

   followed immediately by a far jump instruction, which set CS to a

   valid value for real mode, and flushes the prefetch queue to avoid

   running instructions that have already been decoded in protected

   mode.

   Clears all the flags except ET, especially PG (paging), PE

   (protected-mode enable) and TS (task switch for coprocessor state

   save).  Flushes the TLB after paging has been disabled.  Sets CD and

   NW, to disable the cache on a 486, and invalidates the cache.  This

   is more like the state of a 486 after reset.  I don't know if

   something else should be done for other chips.

   More could be done here to set up the registers as if a CPU reset had

   occurred; hopefully real BIOSes don't assume much. */

unsigned char real_mode_switch [] =

{

        0x66, 0x0f, 0x20, 0xc0,                 /*    movl  %cr0,%eax        */

        0x66, 0x83, 0xe0, 0x11,                 /*    andl  $0x00000011,%eax */

        0x66, 0x0d, 0x00, 0x00, 0x00, 0x60,             /*    orl   $0x60000000,%eax */

        0x66, 0x0f, 0x22, 0xc0,                 /*    movl  %eax,%cr0        */

        0x66, 0x0f, 0x22, 0xd8,                 /*    movl  %eax,%cr3        */

        0x66, 0x0f, 0x20, 0xc3,                 /*    movl  %cr0,%ebx        */

        0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60,       /*    andl  $0x60000000,%ebx */

        0x74, 0x02,                                     /*    jz    f                */

        0x0f, 0x08,                                     /*    invd                   */

        0x24, 0x10,                                     /* f: andb  $0x10,al         */

        0x66, 0x0f, 0x22, 0xc0,                 /*    movl  %eax,%cr0        */

        0xea, 0x00, 0x00, 0xff, 0xff                    /*    ljmp  $0xffff,$0x0000  */

};

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)

{

        if(!reboot_thru_bios) {

                sti();

                /* rebooting needs to touch the page at absolute addr 0 */

                pg0[0] = 7;

                *((unsigned short *)0x472) = reboot_mode;

                for (;;) {

                        int i;

                        for (i=0; i<100; i++) {

                                int j;

                                kb_wait();

                                for(j = 0; j < 100000 ; j++)

                                        /* nothing */;

                                outb(0xfe,0x64);         /* pulse reset low */

                                udelay(10);

                        }

                        __asm__ __volatile__("\tlidt %0": "=m" (no_idt));

                }

        }

        cli ();

        /* Write zero to CMOS register number 0x0f, which the BIOS POST

           routine will recognize as telling it to do a proper reboot.  (Well

           that's what this book in front of me says -- it may only apply to

           the Phoenix BIOS though, it's not clear).  At the same time,

           disable NMIs by setting the top bit in the CMOS address register,

           as we're about to do peculiar things to the CPU.  I'm not sure if

           `outb_p' is needed instead of just `outb'.  Use it to be on the

           safe side. */

        outb_p (0x8f, 0x70);

        outb_p (0x00, 0x71);

        /* Remap the kernel at virtual address zero, as well as offset zero

           from the kernel segment.  This assumes the kernel segment starts at

           virtual address PAGE_OFFSET. */

        memcpy (swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,

                sizeof (swapper_pg_dir [0]) * KERNEL_PGD_PTRS);

        /* Make sure the first page is mapped to the start of physical memory.

           It is normally not mapped, to trap kernel NULL pointer dereferences. */

        pg0 [0] = 7;

        /* Use `swapper_pg_dir' as our page directory.  Don't bother with

           `SET_PAGE_DIR' because interrupts are disabled and we're rebooting.

           This instruction flushes the TLB. */

        __asm__ __volatile__ ("movl %0,%%cr3" : : "a" (swapper_pg_dir) : "memory");

        /* Write 0x1234 to absolute memory location 0x472.  The BIOS reads

           this on booting to tell it to "Bypass memory test (also warm

           boot)".  This seems like a fairly standard thing that gets set by

           REBOOT.COM programs, and the previous reset routine did this

           too. */

        *((unsigned short *)0x472) = reboot_mode;

        /* For the switch to real mode, copy some code to low memory.  It has

           to be in the first 64k because it is running in 16-bit mode, and it

           has to have the same physical and virtual address, because it turns

           off paging.  Copy it near the end of the first page, out of the way

           of BIOS variables. */

        memcpy ((void *) (0x1000 - sizeof (real_mode_switch)),

                real_mode_switch, sizeof (real_mode_switch));

        /* Set up the IDT for real mode. */

        __asm__ __volatile__ ("lidt %0" : : "m" (real_mode_idt));

        /* Set up a GDT from which we can load segment descriptors for real

           mode.  The GDT is not used in real mode; it is just needed here to

           prepare the descriptors. */

        __asm__ __volatile__ ("lgdt %0" : : "m" (real_mode_gdt));

        /* Load the data segment registers, and thus the descriptors ready for

           real mode.  The base address of each segment is 0x100, 16 times the

           selector value being loaded here.  This is so that the segment

           registers don't have to be reloaded after switching to real mode:

           the values are consistent for real mode operation already. */

        __asm__ __volatile__ ("movw $0x0010,%%ax\n"

                                "\tmovw %%ax,%%ds\n"

                                "\tmovw %%ax,%%es\n"

                                "\tmovw %%ax,%%fs\n"

                                "\tmovw %%ax,%%gs\n"

                                "\tmovw %%ax,%%ss" : : : "eax");

        /* Jump to the 16-bit code that we copied earlier.  It disables paging

           and the cache, switches to real mode, and jumps to the BIOS reset

           entry point. */

        __asm__ __volatile__ ("ljmp $0x0008,%0"

                                :

                                : "i" ((void *) (0x1000 - sizeof (real_mode_switch))));

}

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) {

                void * ldt = current->ldt;

                current->ldt = NULL;

                vfree(ldt);

                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, LDT_ENTRIES);

        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;

        if (hard_math) {

                if ((fpvalid = current->used_math) != 0) {

#ifdef __SMP__

                        if (current->flags & PF_USEDFPU)

#else

                        if (last_task_used_math == current)

#endif

                                __asm__("clts ; fnsave %0": :"m" (*fpu));

                        else

                                memcpy(fpu,&current->tss.i387.hard,sizeof(*fpu));

                }

                } else {

                /* We dump the emulator state here.

                   We convert it into standard 387 format first.. */

#ifdef CONFIG_MATH_EMULATION

                int i;

                unsigned long top;

                char (*hardreg)[10];

                struct i387_soft_struct *soft_fpu = &current->tss.i387.soft;

                struct fpu_reg* softreg;

                long int control_word = soft_fpu->cwd;

                fpu->cwd = soft_fpu->cwd;

                fpu->swd = soft_fpu->swd;

                fpu->twd = soft_fpu->twd;

                fpu->fip = soft_fpu->fip;

                fpu->fcs = soft_fpu->fcs;

                fpu->foo = soft_fpu->foo;

                fpu->fos = soft_fpu->fos;

                hardreg = (char (*)[10]) &fpu->st_space[0];

                top = (unsigned long) soft_fpu->top % 8;

                softreg = &soft_fpu->regs[top];

                for (i = top ; i < 8; i ++) {

                        softreg_to_hardreg(softreg, *hardreg, control_word);

                        hardreg++;

                        softreg++;

                }

                softreg = &soft_fpu->regs[0];

                for (i = 0; i < top; i++) {

                        softreg_to_hardreg(softreg, *hardreg, control_word);

                        hardreg++;

                        softreg++;

                }

                fpvalid = 1;

#else /* defined(CONFIG_MATH_EMULATION) */

                fpvalid = 0;

#endif /* !defined(CONFIG_MATH_EMULATION) */

        }

        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;

}