process.c

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/*
 * linux/arch/unicore32/kernel/process.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <stdarg.h>

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/utsname.h>
#include <linux/uaccess.h>
#include <linux/random.h>
#include <linux/gpio.h>
#include <linux/stacktrace.h>

#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/stacktrace.h>

#include "setup.h"

static const char * const processor_modes[] = {
    "UK00", "UK01", "UK02", "UK03", "UK04", "UK05", "UK06", "UK07",
    "UK08", "UK09", "UK0A", "UK0B", "UK0C", "UK0D", "UK0E", "UK0F",
    "USER", "REAL", "INTR", "PRIV", "UK14", "UK15", "UK16", "ABRT",
    "UK18", "UK19", "UK1A", "EXTN", "UK1C", "UK1D", "UK1E", "SUSR"
};

/*
 * The idle thread, has rather strange semantics for calling pm_idle,
 * but this is what x86 does and we need to do the same, so that
 * things like cpuidle get called in the same way.
 */
void cpu_idle(void)
{
    /* endless idle loop with no priority at all */
    while (1) {
        tick_nohz_idle_enter();
        rcu_idle_enter();
        while (!need_resched()) {
            local_irq_disable();
            stop_critical_timings();
            cpu_do_idle();
            local_irq_enable();
            start_critical_timings();
        }
        rcu_idle_exit();
        tick_nohz_idle_exit();
        preempt_enable_no_resched();
        schedule();
        preempt_disable();
    }
}

static char reboot_mode = 'h';

int __init reboot_setup(char *str)
{
    reboot_mode = str[0];
    return 1;
}

__setup("reboot=", reboot_setup);

void machine_halt(void)
{
    gpio_set_value(GPO_SOFT_OFF, 0);
}

/*
 * Function pointers to optional machine specific functions
 */
void (*pm_power_off)(void) = NULL;

void machine_power_off(void)
{
    if (pm_power_off)
        pm_power_off();
    machine_halt();
}

void machine_restart(char *cmd)
{
    /* Disable interrupts first */
    local_irq_disable();

    /*
     * Tell the mm system that we are going to reboot -
     * we may need it to insert some 1:1 mappings so that
     * soft boot works.
     */
    setup_mm_for_reboot(reboot_mode);

    /* Clean and invalidate caches */
    flush_cache_all();

    /* Turn off caching */
    cpu_proc_fin();

    /* Push out any further dirty data, and ensure cache is empty */
    flush_cache_all();

    /*
     * Now handle reboot code.
     */
    if (reboot_mode == 's') {
        /* Jump into ROM at address 0xffff0000 */
        cpu_reset(VECTORS_BASE);
    } else {
        writel(0x00002001, PM_PLLSYSCFG); /* cpu clk = 250M */
        writel(0x00100800, PM_PLLDDRCFG); /* ddr clk =  44M */
        writel(0x00002001, PM_PLLVGACFG); /* vga clk = 250M */

        /* Use on-chip reset capability */
        /* following instructions must be in one icache line */
        __asm__ __volatile__(
            "   .align 5\n\t"
            "   stw %1, [%0]\n\t"
            "201:   ldw r0, [%0]\n\t"
            "   cmpsub.a    r0, #0\n\t"
            "   bne 201b\n\t"
            "   stw %3, [%2]\n\t"
            "   nop; nop; nop\n\t"
            /* prefetch 3 instructions at most */
            :
            : "r" (PM_PMCR),
              "r" (PM_PMCR_CFBSYS | PM_PMCR_CFBDDR
                | PM_PMCR_CFBVGA),
              "r" (RESETC_SWRR),
              "r" (RESETC_SWRR_SRB)
            : "r0", "memory");
    }

    /*
     * Whoops - the architecture was unable to reboot.
     * Tell the user!
     */
    mdelay(1000);
    printk(KERN_EMERG "Reboot failed -- System halted\n");
    do { } while (1);
}

void __show_regs(struct pt_regs *regs)
{
    unsigned long flags;
    char buf[64];

    printk(KERN_DEFAULT "CPU: %d    %s  (%s %.*s)\n",
        raw_smp_processor_id(), print_tainted(),
        init_utsname()->release,
        (int)strcspn(init_utsname()->version, " "),
        init_utsname()->version);
    print_symbol("PC is at %s\n", instruction_pointer(regs));
    print_symbol("LR is at %s\n", regs->UCreg_lr);
    printk(KERN_DEFAULT "pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
           "sp : %08lx  ip : %08lx  fp : %08lx\n",
        regs->UCreg_pc, regs->UCreg_lr, regs->UCreg_asr,
        regs->UCreg_sp, regs->UCreg_ip, regs->UCreg_fp);
    printk(KERN_DEFAULT "r26: %08lx  r25: %08lx  r24: %08lx\n",
        regs->UCreg_26, regs->UCreg_25,
        regs->UCreg_24);
    printk(KERN_DEFAULT "r23: %08lx  r22: %08lx  r21: %08lx  r20: %08lx\n",
        regs->UCreg_23, regs->UCreg_22,
        regs->UCreg_21, regs->UCreg_20);
    printk(KERN_DEFAULT "r19: %08lx  r18: %08lx  r17: %08lx  r16: %08lx\n",
        regs->UCreg_19, regs->UCreg_18,
        regs->UCreg_17, regs->UCreg_16);
    printk(KERN_DEFAULT "r15: %08lx  r14: %08lx  r13: %08lx  r12: %08lx\n",
        regs->UCreg_15, regs->UCreg_14,
        regs->UCreg_13, regs->UCreg_12);
    printk(KERN_DEFAULT "r11: %08lx  r10: %08lx  r9 : %08lx  r8 : %08lx\n",
        regs->UCreg_11, regs->UCreg_10,
        regs->UCreg_09, regs->UCreg_08);
    printk(KERN_DEFAULT "r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
        regs->UCreg_07, regs->UCreg_06,
        regs->UCreg_05, regs->UCreg_04);
    printk(KERN_DEFAULT "r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
        regs->UCreg_03, regs->UCreg_02,
        regs->UCreg_01, regs->UCreg_00);

    flags = regs->UCreg_asr;
    buf[0] = flags & PSR_S_BIT ? 'S' : 's';
    buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
    buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
    buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
    buf[4] = '\0';

    printk(KERN_DEFAULT "Flags: %s  INTR o%s  REAL o%s  Mode %s  Segment %s\n",
        buf, interrupts_enabled(regs) ? "n" : "ff",
        fast_interrupts_enabled(regs) ? "n" : "ff",
        processor_modes[processor_mode(regs)],
        segment_eq(get_fs(), get_ds()) ? "kernel" : "user");
    {
        unsigned int ctrl;

        buf[0] = '\0';
        {
            unsigned int transbase;
            asm("movc %0, p0.c2, #0\n"
                : "=r" (transbase));
            snprintf(buf, sizeof(buf), "  Table: %08x", transbase);
        }
        asm("movc %0, p0.c1, #0\n" : "=r" (ctrl));

        printk(KERN_DEFAULT "Control: %08x%s\n", ctrl, buf);
    }
}

void show_regs(struct pt_regs *regs)
{
    printk(KERN_DEFAULT "\n");
    printk(KERN_DEFAULT "Pid: %d, comm: %20s\n",
            task_pid_nr(current), current->comm);
    __show_regs(regs);
    __backtrace();
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

void flush_thread(void)
{
    struct thread_info *thread = current_thread_info();
    struct task_struct *tsk = current;

    memset(thread->used_cp, 0, sizeof(thread->used_cp));
    memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
#ifdef CONFIG_UNICORE_FPU_F64
    memset(&thread->fpstate, 0, sizeof(struct fp_state));
#endif
}

void release_thread(struct task_struct *dead_task)
{
}

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");

int
copy_thread(unsigned long clone_flags, unsigned long stack_start,
        unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
{
    struct thread_info *thread = task_thread_info(p);
    struct pt_regs *childregs = task_pt_regs(p);

    memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
    thread->cpu_context.sp = (unsigned long)childregs;
    if (unlikely(!regs)) {
        thread->cpu_context.pc = (unsigned long)ret_from_kernel_thread;
        thread->cpu_context.r4 = stack_start;
        thread->cpu_context.r5 = stk_sz;
        memset(childregs, 0, sizeof(struct pt_regs));
    } else {
        thread->cpu_context.pc = (unsigned long)ret_from_fork;
        *childregs = *regs;
        childregs->UCreg_00 = 0;
        childregs->UCreg_sp = stack_start;

        if (clone_flags & CLONE_SETTLS)
            childregs->UCreg_16 = regs->UCreg_03;
    }
    return 0;
}

/*
 * Fill in the task's elfregs structure for a core dump.
 */
int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
{
    elf_core_copy_regs(elfregs, task_pt_regs(t));
    return 1;
}

/*
 * fill in the fpe structure for a core dump...
 */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fp)
{
    struct thread_info *thread = current_thread_info();
    int used_math = thread->used_cp[1] | thread->used_cp[2];

#ifdef CONFIG_UNICORE_FPU_F64
    if (used_math)
        memcpy(fp, &thread->fpstate, sizeof(*fp));
#endif
    return used_math != 0;
}
EXPORT_SYMBOL(dump_fpu);

unsigned long get_wchan(struct task_struct *p)
{
    struct stackframe frame;
    int count = 0;
    if (!p || p == current || p->state == TASK_RUNNING)
        return 0;

    frame.fp = thread_saved_fp(p);
    frame.sp = thread_saved_sp(p);
    frame.lr = 0;           /* recovered from the stack */
    frame.pc = thread_saved_pc(p);
    do {
        int ret = unwind_frame(&frame);
        if (ret < 0)
            return 0;
        if (!in_sched_functions(frame.pc))
            return frame.pc;
    } while ((count++) < 16);
    return 0;
}

unsigned long arch_randomize_brk(struct mm_struct *mm)
{
    unsigned long range_end = mm->brk + 0x02000000;
    return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
}

/*
 * The vectors page is always readable from user space for the
 * atomic helpers and the signal restart code.  Let's declare a mapping
 * for it so it is visible through ptrace and /proc/<pid>/mem.
 */

int vectors_user_mapping(void)
{
    struct mm_struct *mm = current->mm;
    return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
                       VM_READ | VM_EXEC |
                       VM_MAYREAD | VM_MAYEXEC |
                       VM_DONTEXPAND | VM_DONTDUMP,
                       NULL);
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
    return (vma->vm_start == 0xffff0000) ? "[vectors]" : NULL;
}