process.c

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/*
 * Copyright (C) 2008-2009 Michal Simek <[email protected]>
 * Copyright (C) 2008-2009 PetaLogix
 * Copyright (C) 2006 Atmark Techno, Inc.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/bitops.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h> /* for USER_DS macros */
#include <asm/cacheflush.h>

void show_regs(struct pt_regs *regs)
{
    printk(KERN_INFO " Registers dump: mode=%X\r\n", regs->pt_mode);
    printk(KERN_INFO " r1=%08lX, r2=%08lX, r3=%08lX, r4=%08lX\n",
                regs->r1, regs->r2, regs->r3, regs->r4);
    printk(KERN_INFO " r5=%08lX, r6=%08lX, r7=%08lX, r8=%08lX\n",
                regs->r5, regs->r6, regs->r7, regs->r8);
    printk(KERN_INFO " r9=%08lX, r10=%08lX, r11=%08lX, r12=%08lX\n",
                regs->r9, regs->r10, regs->r11, regs->r12);
    printk(KERN_INFO " r13=%08lX, r14=%08lX, r15=%08lX, r16=%08lX\n",
                regs->r13, regs->r14, regs->r15, regs->r16);
    printk(KERN_INFO " r17=%08lX, r18=%08lX, r19=%08lX, r20=%08lX\n",
                regs->r17, regs->r18, regs->r19, regs->r20);
    printk(KERN_INFO " r21=%08lX, r22=%08lX, r23=%08lX, r24=%08lX\n",
                regs->r21, regs->r22, regs->r23, regs->r24);
    printk(KERN_INFO " r25=%08lX, r26=%08lX, r27=%08lX, r28=%08lX\n",
                regs->r25, regs->r26, regs->r27, regs->r28);
    printk(KERN_INFO " r29=%08lX, r30=%08lX, r31=%08lX, rPC=%08lX\n",
                regs->r29, regs->r30, regs->r31, regs->pc);
    printk(KERN_INFO " msr=%08lX, ear=%08lX, esr=%08lX, fsr=%08lX\n",
                regs->msr, regs->ear, regs->esr, regs->fsr);
}

void (*pm_idle)(void);
void (*pm_power_off)(void) = NULL;
EXPORT_SYMBOL(pm_power_off);

static int hlt_counter = 1;

void disable_hlt(void)
{
    hlt_counter++;
}
EXPORT_SYMBOL(disable_hlt);

void enable_hlt(void)
{
    hlt_counter--;
}
EXPORT_SYMBOL(enable_hlt);

static int __init nohlt_setup(char *__unused)
{
    hlt_counter = 1;
    return 1;
}
__setup("nohlt", nohlt_setup);

static int __init hlt_setup(char *__unused)
{
    hlt_counter = 0;
    return 1;
}
__setup("hlt", hlt_setup);

void default_idle(void)
{
    if (likely(hlt_counter)) {
        local_irq_disable();
        stop_critical_timings();
        cpu_relax();
        start_critical_timings();
        local_irq_enable();
    } else {
        clear_thread_flag(TIF_POLLING_NRFLAG);
        smp_mb__after_clear_bit();
        local_irq_disable();
        while (!need_resched())
            cpu_sleep();
        local_irq_enable();
        set_thread_flag(TIF_POLLING_NRFLAG);
    }
}

void cpu_idle(void)
{
    set_thread_flag(TIF_POLLING_NRFLAG);

    /* endless idle loop with no priority at all */
    while (1) {
        void (*idle)(void) = pm_idle;

        if (!idle)
            idle = default_idle;

        tick_nohz_idle_enter();
        rcu_idle_enter();
        while (!need_resched())
            idle();
        rcu_idle_exit();
        tick_nohz_idle_exit();

        schedule_preempt_disabled();
        check_pgt_cache();
    }
}

void flush_thread(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 = task_pt_regs(p);
    struct thread_info *ti = task_thread_info(p);

    *childregs = *regs;
    if (user_mode(regs))
        childregs->r1 = usp;
    else
        childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;

#ifndef CONFIG_MMU
    memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
    ti->cpu_context.r1 = (unsigned long)childregs;
    ti->cpu_context.msr = (unsigned long)childregs->msr;
#else

    /* if creating a kernel thread then update the current reg (we don't
     * want to use the parent's value when restoring by POP_STATE) */
    if (kernel_mode(regs))
        /* save new current on stack to use POP_STATE */
        childregs->CURRENT_TASK = (unsigned long)p;
    /* if returning to user then use the parent's value of this register */

    /* if we're creating a new kernel thread then just zeroing all
     * the registers. That's OK for a brand new thread.*/
    /* Pls. note that some of them will be restored in POP_STATE */
    if (kernel_mode(regs))
        memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
    /* if this thread is created for fork/vfork/clone, then we want to
     * restore all the parent's context */
    /* in addition to the registers which will be restored by POP_STATE */
    else {
        ti->cpu_context = *(struct cpu_context *)regs;
        childregs->msr |= MSR_UMS;
    }

    /* FIXME STATE_SAVE_PT_OFFSET; */
    ti->cpu_context.r1  = (unsigned long)childregs;
    /* we should consider the fact that childregs is a copy of the parent
     * regs which were saved immediately after entering the kernel state
     * before enabling VM. This MSR will be restored in switch_to and
     * RETURN() and we want to have the right machine state there
     * specifically this state must have INTs disabled before and enabled
     * after performing rtbd
     * compose the right MSR for RETURN(). It will work for switch_to also
     * excepting for VM and UMS
     * don't touch UMS , CARRY and cache bits
     * right now MSR is a copy of parent one */
    childregs->msr |= MSR_BIP;
    childregs->msr &= ~MSR_EIP;
    childregs->msr |= MSR_IE;
    childregs->msr &= ~MSR_VM;
    childregs->msr |= MSR_VMS;
    childregs->msr |= MSR_EE; /* exceptions will be enabled*/

    ti->cpu_context.msr = (childregs->msr|MSR_VM);
    ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
    ti->cpu_context.msr &= ~MSR_IE;
#endif
    ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;

    /*
     *  r21 is the thread reg, r10 is 6th arg to clone
     *  which contains TLS area
     */
    if (clone_flags & CLONE_SETTLS)
        childregs->r21 = childregs->r10;

    return 0;
}

#ifndef CONFIG_MMU
/*
 * Return saved PC of a blocked thread.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
    struct cpu_context *ctx =
        &(((struct thread_info *)(tsk->stack))->cpu_context);

    /* Check whether the thread is blocked in resume() */
    if (in_sched_functions(ctx->r15))
        return (unsigned long)ctx->r15;
    else
        return ctx->r14;
}
#endif

static void kernel_thread_helper(int (*fn)(void *), void *arg)
{
    fn(arg);
    do_exit(-1);
}

int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
    struct pt_regs regs;

    memset(&regs, 0, sizeof(regs));
    /* store them in non-volatile registers */
    regs.r5 = (unsigned long)fn;
    regs.r6 = (unsigned long)arg;
    local_save_flags(regs.msr);
    regs.pc = (unsigned long)kernel_thread_helper;
    regs.pt_mode = 1;

    return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
            &regs, 0, NULL, NULL);
}
EXPORT_SYMBOL_GPL(kernel_thread);

unsigned long get_wchan(struct task_struct *p)
{
/* TBD (used by procfs) */
    return 0;
}

/* Set up a thread for executing a new program */
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
{
    regs->pc = pc;
    regs->r1 = usp;
    regs->pt_mode = 0;
#ifdef CONFIG_MMU
    regs->msr |= MSR_UMS;
#endif
}

#ifdef CONFIG_MMU
#include <linux/elfcore.h>
/*
 * Set up a thread for executing a new program
 */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
{
    return 0; /* MicroBlaze has no separate FPU registers */
}
#endif /* CONFIG_MMU */