process.c

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/* process.c: FRV specific parts of process handling
 *
 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 * - Derived from arch/m68k/kernel/process.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
#include <linux/rcupdate.h>

#include <asm/asm-offsets.h>
#include <asm/uaccess.h>
#include <asm/setup.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
#include <asm/gdb-stub.h>
#include <asm/mb-regs.h>

#include "local.h"

asmlinkage void ret_from_fork(void);
asmlinkage void ret_from_kernel_thread(void);

#include <asm/pgalloc.h>

void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

static void core_sleep_idle(void)
{
#ifdef LED_DEBUG_SLEEP
    /* Show that we're sleeping... */
    __set_LEDS(0x55aa);
#endif
    frv_cpu_core_sleep();
#ifdef LED_DEBUG_SLEEP
    /* ... and that we woke up */
    __set_LEDS(0);
#endif
    mb();
}

void (*idle)(void) = core_sleep_idle;

/*
 * The idle thread. There's no useful work to be
 * done, so just try to conserve power and have a
 * low exit latency (ie sit in a loop waiting for
 * somebody to say that they'd like to reschedule)
 */
void cpu_idle(void)
{
    /* endless idle loop with no priority at all */
    while (1) {
        rcu_idle_enter();
        while (!need_resched()) {
            check_pgt_cache();

            if (!frv_dma_inprogress && idle)
                idle();
        }
        rcu_idle_exit();

        schedule_preempt_disabled();
    }
}

void machine_restart(char * __unused)
{
    unsigned long reset_addr;
#ifdef CONFIG_GDBSTUB
    gdbstub_exit(0);
#endif

    if (PSR_IMPLE(__get_PSR()) == PSR_IMPLE_FR551)
        reset_addr = 0xfefff500;
    else
        reset_addr = 0xfeff0500;

    /* Software reset. */
    asm volatile("      dcef @(gr0,gr0),1 ! membar !"
             "      sti     %1,@(%0,0) !"
             "      nop ! nop ! nop ! nop ! nop ! "
             "      nop ! nop ! nop ! nop ! nop ! "
             "      nop ! nop ! nop ! nop ! nop ! "
             "      nop ! nop ! nop ! nop ! nop ! "
             : : "r" (reset_addr), "r" (1) );

    for (;;)
        ;
}

void machine_halt(void)
{
#ifdef CONFIG_GDBSTUB
    gdbstub_exit(0);
#endif

    for (;;);
}

void machine_power_off(void)
{
#ifdef CONFIG_GDBSTUB
    gdbstub_exit(0);
#endif

    for (;;);
}

void flush_thread(void)
{
    /* nothing */
}

inline unsigned long user_stack(const struct pt_regs *regs)
{
    while (regs->next_frame)
        regs = regs->next_frame;
    return user_mode(regs) ? regs->sp : 0;
}

asmlinkage int sys_fork(void)
{
#ifndef CONFIG_MMU
    /* fork almost works, enough to trick you into looking elsewhere:-( */
    return -EINVAL;
#else
    return do_fork(SIGCHLD, user_stack(__frame), __frame, 0, NULL, NULL);
#endif
}

asmlinkage int sys_vfork(void)
{
    return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, user_stack(__frame), __frame, 0,
               NULL, NULL);
}

/*****************************************************************************/
/*
 * clone a process
 * - tlsptr is retrieved by copy_thread()
 */
asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
             int __user *parent_tidptr, int __user *child_tidptr,
             int __user *tlsptr)
{
    if (!newsp)
        newsp = user_stack(__frame);
    return do_fork(clone_flags, newsp, __frame, 0, parent_tidptr, child_tidptr);
} /* end sys_clone() */

/*
 * set up the kernel stack and exception frames for a new process
 */
int copy_thread(unsigned long clone_flags,
        unsigned long usp, unsigned long arg,
        struct task_struct *p, struct pt_regs *regs)
{
    struct pt_regs *childregs;

    childregs = (struct pt_regs *)
        (task_stack_page(p) + THREAD_SIZE - FRV_FRAME0_SIZE);

    /* set up the userspace frame (the only place that the USP is stored) */
    *childregs = *__kernel_frame0_ptr;

    p->set_child_tid = p->clear_child_tid = NULL;

    p->thread.frame  = childregs;
    p->thread.curr   = p;
    p->thread.sp     = (unsigned long) childregs;
    p->thread.fp     = 0;
    p->thread.lr     = 0;
    p->thread.frame0 = childregs;

    if (unlikely(!regs)) {
        childregs->gr9 = usp; /* function */
        childregs->gr8 = arg;
        p->thread.pc = (unsigned long) ret_from_kernel_thread;
        save_user_regs(p->thread.user);
        return 0;
    }

    /* set up the userspace frame (the only place that the USP is stored) */
    *childregs = *regs;

    childregs->sp       = usp;
    childregs->next_frame   = NULL;

    p->thread.pc = (unsigned long) ret_from_fork;

    /* the new TLS pointer is passed in as arg #5 to sys_clone() */
    if (clone_flags & CLONE_SETTLS)
        childregs->gr29 = childregs->gr12;

    save_user_regs(p->thread.user);

    return 0;
} /* end copy_thread() */

unsigned long get_wchan(struct task_struct *p)
{
    struct pt_regs *regs0;
    unsigned long fp, pc;
    unsigned long stack_limit;
    int count = 0;
    if (!p || p == current || p->state == TASK_RUNNING)
        return 0;

    stack_limit = (unsigned long) (p + 1);
    fp = p->thread.fp;
    regs0 = p->thread.frame0;

    do {
        if (fp < stack_limit || fp >= (unsigned long) regs0 || fp & 3)
            return 0;

        pc = ((unsigned long *) fp)[2];

        /* FIXME: This depends on the order of these functions. */
        if (!in_sched_functions(pc))
            return pc;

        fp = *(unsigned long *) fp;
    } while (count++ < 16);

    return 0;
}

unsigned long thread_saved_pc(struct task_struct *tsk)
{
    /* Check whether the thread is blocked in resume() */
    if (in_sched_functions(tsk->thread.pc))
        return ((unsigned long *)tsk->thread.fp)[2];
    else
        return tsk->thread.pc;
}

int elf_check_arch(const struct elf32_hdr *hdr)
{
    unsigned long hsr0 = __get_HSR(0);
    unsigned long psr = __get_PSR();

    if (hdr->e_machine != EM_FRV)
        return 0;

    switch (hdr->e_flags & EF_FRV_GPR_MASK) {
    case EF_FRV_GPR64:
        if ((hsr0 & HSR0_GRN) == HSR0_GRN_32)
            return 0;
    case EF_FRV_GPR32:
    case 0:
        break;
    default:
        return 0;
    }

    switch (hdr->e_flags & EF_FRV_FPR_MASK) {
    case EF_FRV_FPR64:
        if ((hsr0 & HSR0_FRN) == HSR0_FRN_32)
            return 0;
    case EF_FRV_FPR32:
    case EF_FRV_FPR_NONE:
    case 0:
        break;
    default:
        return 0;
    }

    if ((hdr->e_flags & EF_FRV_MULADD) == EF_FRV_MULADD)
        if (PSR_IMPLE(psr) != PSR_IMPLE_FR405 &&
            PSR_IMPLE(psr) != PSR_IMPLE_FR451)
            return 0;

    switch (hdr->e_flags & EF_FRV_CPU_MASK) {
    case EF_FRV_CPU_GENERIC:
        break;
    case EF_FRV_CPU_FR300:
    case EF_FRV_CPU_SIMPLE:
    case EF_FRV_CPU_TOMCAT:
    default:
        return 0;
    case EF_FRV_CPU_FR400:
        if (PSR_IMPLE(psr) != PSR_IMPLE_FR401 &&
            PSR_IMPLE(psr) != PSR_IMPLE_FR405 &&
            PSR_IMPLE(psr) != PSR_IMPLE_FR451 &&
            PSR_IMPLE(psr) != PSR_IMPLE_FR551)
            return 0;
        break;
    case EF_FRV_CPU_FR450:
        if (PSR_IMPLE(psr) != PSR_IMPLE_FR451)
            return 0;
        break;
    case EF_FRV_CPU_FR500:
        if (PSR_IMPLE(psr) != PSR_IMPLE_FR501)
            return 0;
        break;
    case EF_FRV_CPU_FR550:
        if (PSR_IMPLE(psr) != PSR_IMPLE_FR551)
            return 0;
        break;
    }

    return 1;
}

int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
{
    memcpy(fpregs,
           &current->thread.user->f,
           sizeof(current->thread.user->f));
    return 1;
}