process.c

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/*
 *  Copyright (C) 2000-2003  Axis Communications AB
 *
 *  Authors:   Bjorn Wesen ([email protected])
 *             Mikael Starvik ([email protected])
 *             Tobias Anderberg ([email protected]), CRISv32 port.
 *
 * This file handles the architecture-dependent parts of process handling..
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <hwregs/reg_rdwr.h>
#include <hwregs/reg_map.h>
#include <hwregs/timer_defs.h>
#include <hwregs/intr_vect_defs.h>

extern void stop_watchdog(void);

extern int cris_hlt_counter;

/* We use this if we don't have any better idle routine. */
void default_idle(void)
{
    local_irq_disable();
    if (!need_resched() && !cris_hlt_counter) {
            /* Halt until exception. */
        __asm__ volatile("ei    \n\t"
                                 "halt      ");
    }
    local_irq_enable();
}

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

extern void deconfigure_bp(long pid);
void exit_thread(void)
{
    deconfigure_bp(current->pid);
}

/*
 * If the watchdog is enabled, disable interrupts and enter an infinite loop.
 * The watchdog will reset the CPU after 0.1s. If the watchdog isn't enabled
 * then enable it and wait.
 */
extern void arch_enable_nmi(void);

void
hard_reset_now(void)
{
    /*
     * Don't declare this variable elsewhere.  We don't want any other
     * code to know about it than the watchdog handler in entry.S and
     * this code, implementing hard reset through the watchdog.
     */
#if defined(CONFIG_ETRAX_WATCHDOG)
    extern int cause_of_death;
#endif

    printk("*** HARD RESET ***\n");
    local_irq_disable();

#if defined(CONFIG_ETRAX_WATCHDOG)
    cause_of_death = 0xbedead;
#else
{
    reg_timer_rw_wd_ctrl wd_ctrl = {0};

    stop_watchdog();

    wd_ctrl.key = 16;   /* Arbitrary key. */
    wd_ctrl.cnt = 1;    /* Minimum time. */
    wd_ctrl.cmd = regk_timer_start;

        arch_enable_nmi();
    REG_WR(timer, regi_timer0, rw_wd_ctrl, wd_ctrl);
}
#endif

    while (1)
        ; /* Wait for reset. */
}

/*
 * Return saved PC of a blocked thread.
 */
unsigned long thread_saved_pc(struct task_struct *t)
{
    return task_pt_regs(t)->erp;
}

static void
kernel_thread_helper(void* dummy, int (*fn)(void *), void * arg)
{
    fn(arg);
    do_exit(-1); /* Should never be called, return bad exit value. */
}

/* Create a kernel thread. */
int
kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
    struct pt_regs regs;

    memset(&regs, 0, sizeof(regs));

        /* Don't use r10 since that is set to 0 in copy_thread. */
    regs.r11 = (unsigned long) fn;
    regs.r12 = (unsigned long) arg;
    regs.erp = (unsigned long) kernel_thread_helper;
    regs.ccs = 1 << (I_CCS_BITNR + CCS_SHIFT);

    /* Create the new process. */
        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}

/*
 * Setup the child's kernel stack with a pt_regs and call switch_stack() on it.
 * It will be unnested during _resume and _ret_from_sys_call when the new thread
 * is scheduled.
 *
 * Also setup the thread switching structure which is used to keep
 * thread-specific data during _resumes.
 */

extern asmlinkage void ret_from_fork(void);

int
copy_thread(unsigned long clone_flags, unsigned long usp,
    unsigned long unused,
    struct task_struct *p, struct pt_regs *regs)
{
    struct pt_regs *childregs;
    struct switch_stack *swstack;

    /*
     * Put the pt_regs structure at the end of the new kernel stack page and
     * fix it up. Note: the task_struct doubles as the kernel stack for the
     * task.
     */
    childregs = task_pt_regs(p);
    *childregs = *regs; /* Struct copy of pt_regs. */
        p->set_child_tid = p->clear_child_tid = NULL;
        childregs->r10 = 0; /* Child returns 0 after a fork/clone. */

    /* Set a new TLS ?
     * The TLS is in $mof because it is the 5th argument to sys_clone.
     */
    if (p->mm && (clone_flags & CLONE_SETTLS)) {
        task_thread_info(p)->tls = regs->mof;
    }

    /* Put the switch stack right below the pt_regs. */
    swstack = ((struct switch_stack *) childregs) - 1;

    /* Parameter to ret_from_sys_call. 0 is don't restart the syscall. */
    swstack->r9 = 0;

    /*
     * We want to return into ret_from_sys_call after the _resume.
     * ret_from_fork will call ret_from_sys_call.
     */
    swstack->return_ip = (unsigned long) ret_from_fork;

    /* Fix the user-mode and kernel-mode stackpointer. */
    p->thread.usp = usp;
    p->thread.ksp = (unsigned long) swstack;

    return 0;
}

/*
 * Be aware of the "magic" 7th argument in the four system-calls below.
 * They need the latest stackframe, which is put as the 7th argument by
 * entry.S. The previous arguments are dummies or actually used, but need
 * to be defined to reach the 7th argument.
 *
 * N.B.: Another method to get the stackframe is to use current_regs(). But
 * it returns the latest stack-frame stacked when going from _user mode_ and
 * some of these (at least sys_clone) are called from kernel-mode sometimes
 * (for example during kernel_thread, above) and thus cannot use it. Thus,
 * to be sure not to get any surprises, we use the method for the other calls
 * as well.
 */
asmlinkage int
sys_fork(long r10, long r11, long r12, long r13, long mof, long srp,
    struct pt_regs *regs)
{
    return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
}

/* FIXME: Is parent_tid/child_tid really third/fourth argument? Update lib? */
asmlinkage int
sys_clone(unsigned long newusp, unsigned long flags, int *parent_tid, int *child_tid,
    unsigned long tls, long srp, struct pt_regs *regs)
{
    if (!newusp)
        newusp = rdusp();

    return do_fork(flags, newusp, regs, 0, parent_tid, child_tid);
}

/*
 * vfork is a system call in i386 because of register-pressure - maybe
 * we can remove it and handle it in libc but we put it here until then.
 */
asmlinkage int
sys_vfork(long r10, long r11, long r12, long r13, long mof, long srp,
    struct pt_regs *regs)
{
    return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL, NULL);
}

/* sys_execve() executes a new program. */
asmlinkage int
sys_execve(const char *fname,
       const char *const *argv,
       const char *const *envp, long r13, long mof, long srp,
       struct pt_regs *regs)
{
    int error;
    struct filename *filename;

    filename = getname(fname);
    error = PTR_ERR(filename);

    if (IS_ERR(filename))
            goto out;

    error = do_execve(filename->name, argv, envp, regs);
    putname(filename);
 out:
    return error;
}

unsigned long
get_wchan(struct task_struct *p)
{
    /* TODO */
    return 0;
}
#undef last_sched
#undef first_sched

void show_regs(struct pt_regs * regs)
{
    unsigned long usp = rdusp();
        printk("ERP: %08lx SRP: %08lx  CCS: %08lx USP: %08lx MOF: %08lx\n",
        regs->erp, regs->srp, regs->ccs, usp, regs->mof);

    printk(" r0: %08lx  r1: %08lx   r2: %08lx  r3: %08lx\n",
        regs->r0, regs->r1, regs->r2, regs->r3);

    printk(" r4: %08lx  r5: %08lx   r6: %08lx  r7: %08lx\n",
        regs->r4, regs->r5, regs->r6, regs->r7);

    printk(" r8: %08lx  r9: %08lx  r10: %08lx r11: %08lx\n",
        regs->r8, regs->r9, regs->r10, regs->r11);

    printk("r12: %08lx r13: %08lx oR10: %08lx\n",
        regs->r12, regs->r13, regs->orig_r10);
}