process.c

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/*
 *  linux/arch/arm/kernel/process.c
 *
 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
 *  Original Copyright (C) 1995  Linus Torvalds
 *
 * 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/export.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/user.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/hw_breakpoint.h>
#include <linux/cpuidle.h>
#include <linux/leds.h>

#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/thread_notify.h>
#include <asm/stacktrace.h>
#include <asm/mach/time.h>

#ifdef CONFIG_CC_STACKPROTECTOR
#include <linux/stackprotector.h>
unsigned long __stack_chk_guard __read_mostly;
EXPORT_SYMBOL(__stack_chk_guard);
#endif

static const char *processor_modes[] = {
  "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
  "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
};

static const char *isa_modes[] = {
  "ARM" , "Thumb" , "Jazelle", "ThumbEE"
};

extern void setup_mm_for_reboot(void);

static volatile int hlt_counter;

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;
}

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

__setup("nohlt", nohlt_setup);
__setup("hlt", hlt_setup);

extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
typedef void (*phys_reset_t)(unsigned long);

/*
 * A temporary stack to use for CPU reset. This is static so that we
 * don't clobber it with the identity mapping. When running with this
 * stack, any references to the current task *will not work* so you
 * should really do as little as possible before jumping to your reset
 * code.
 */
static u64 soft_restart_stack[16];

static void __soft_restart(void *addr)
{
    phys_reset_t phys_reset;

    /* Take out a flat memory mapping. */
    setup_mm_for_reboot();

    /* 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();

    /* Switch to the identity mapping. */
    phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
    phys_reset((unsigned long)addr);

    /* Should never get here. */
    BUG();
}

void soft_restart(unsigned long addr)
{
    u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);

    /* Disable interrupts first */
    local_irq_disable();
    local_fiq_disable();

    /* Disable the L2 if we're the last man standing. */
    if (num_online_cpus() == 1)
        outer_disable();

    /* Change to the new stack and continue with the reset. */
    call_with_stack(__soft_restart, (void *)addr, (void *)stack);

    /* Should never get here. */
    BUG();
}

static void null_restart(char mode, const char *cmd)
{
}

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

void (*arm_pm_restart)(char str, const char *cmd) = null_restart;
EXPORT_SYMBOL_GPL(arm_pm_restart);

/*
 * This is our default idle handler.
 */

void (*arm_pm_idle)(void);

static void default_idle(void)
{
    if (arm_pm_idle)
        arm_pm_idle();
    else
        cpu_do_idle();
    local_irq_enable();
}

void (*pm_idle)(void) = default_idle;
EXPORT_SYMBOL(pm_idle);

/*
 * 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.  The only difference
 * is that we always respect 'hlt_counter' to prevent low power idle.
 */
void cpu_idle(void)
{
    local_fiq_enable();

    /* endless idle loop with no priority at all */
    while (1) {
        tick_nohz_idle_enter();
        rcu_idle_enter();
        ledtrig_cpu(CPU_LED_IDLE_START);
        while (!need_resched()) {
#ifdef CONFIG_HOTPLUG_CPU
            if (cpu_is_offline(smp_processor_id()))
                cpu_die();
#endif

            /*
             * We need to disable interrupts here
             * to ensure we don't miss a wakeup call.
             */
            local_irq_disable();
#ifdef CONFIG_PL310_ERRATA_769419
            wmb();
#endif
            if (hlt_counter) {
                local_irq_enable();
                cpu_relax();
            } else if (!need_resched()) {
                stop_critical_timings();
                if (cpuidle_idle_call())
                    pm_idle();
                start_critical_timings();
                /*
                 * pm_idle functions must always
                 * return with IRQs enabled.
                 */
                WARN_ON(irqs_disabled());
            } else
                local_irq_enable();
        }
        ledtrig_cpu(CPU_LED_IDLE_END);
        rcu_idle_exit();
        tick_nohz_idle_exit();
        schedule_preempt_disabled();
    }
}

static char reboot_mode = 'h';

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

__setup("reboot=", reboot_setup);

void machine_shutdown(void)
{
#ifdef CONFIG_SMP
    smp_send_stop();
#endif
}

void machine_halt(void)
{
    machine_shutdown();
    local_irq_disable();
    while (1);
}

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

void machine_restart(char *cmd)
{
    machine_shutdown();

    arm_pm_restart(reboot_mode, cmd);

    /* Give a grace period for failure to restart of 1s */
    mdelay(1000);

    /* Whoops - the platform was unable to reboot. Tell the user! */
    printk("Reboot failed -- System halted\n");
    local_irq_disable();
    while (1);
}

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

    printk("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->ARM_lr);
    printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
           "sp : %08lx  ip : %08lx  fp : %08lx\n",
        regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
        regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
    printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
        regs->ARM_r10, regs->ARM_r9,
        regs->ARM_r8);
    printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
        regs->ARM_r7, regs->ARM_r6,
        regs->ARM_r5, regs->ARM_r4);
    printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
        regs->ARM_r3, regs->ARM_r2,
        regs->ARM_r1, regs->ARM_r0);

    flags = regs->ARM_cpsr;
    buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
    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("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
        buf, interrupts_enabled(regs) ? "n" : "ff",
        fast_interrupts_enabled(regs) ? "n" : "ff",
        processor_modes[processor_mode(regs)],
        isa_modes[isa_mode(regs)],
        get_fs() == get_ds() ? "kernel" : "user");
#ifdef CONFIG_CPU_CP15
    {
        unsigned int ctrl;

        buf[0] = '\0';
#ifdef CONFIG_CPU_CP15_MMU
        {
            unsigned int transbase, dac;
            asm("mrc p15, 0, %0, c2, c0\n\t"
                "mrc p15, 0, %1, c3, c0\n"
                : "=r" (transbase), "=r" (dac));
            snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
                transbase, dac);
        }
#endif
        asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));

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

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

ATOMIC_NOTIFIER_HEAD(thread_notify_head);

EXPORT_SYMBOL_GPL(thread_notify_head);

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
    thread_notify(THREAD_NOTIFY_EXIT, current_thread_info());
}

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

    flush_ptrace_hw_breakpoint(tsk);

    memset(thread->used_cp, 0, sizeof(thread->used_cp));
    memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
    memset(&thread->fpstate, 0, sizeof(union fp_state));

    thread_notify(THREAD_NOTIFY_FLUSH, thread);
}

void release_thread(struct task_struct *dead_task)
{
}

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

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));

    if (likely(regs)) {
        *childregs = *regs;
        childregs->ARM_r0 = 0;
        childregs->ARM_sp = stack_start;
    } else {
        memset(childregs, 0, sizeof(struct pt_regs));
        thread->cpu_context.r4 = stk_sz;
        thread->cpu_context.r5 = stack_start;
        childregs->ARM_cpsr = SVC_MODE;
    }
    thread->cpu_context.pc = (unsigned long)ret_from_fork;
    thread->cpu_context.sp = (unsigned long)childregs;

    clear_ptrace_hw_breakpoint(p);

    if (clone_flags & CLONE_SETTLS)
        thread->tp_value = regs->ARM_r3;

    thread_notify(THREAD_NOTIFY_COPY, thread);

    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, struct user_fp *fp)
{
    struct thread_info *thread = current_thread_info();
    int used_math = thread->used_cp[1] | thread->used_cp[2];

    if (used_math)
        memcpy(fp, &thread->fpstate.soft, sizeof (*fp));

    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;
}

#ifdef CONFIG_MMU
/*
 * The vectors page is always readable from user space for the
 * atomic helpers and the signal restart code. Insert it into the
 * gate_vma so that it is visible through ptrace and /proc/<pid>/mem.
 */
static struct vm_area_struct gate_vma;

static int __init gate_vma_init(void)
{
    gate_vma.vm_start   = 0xffff0000;
    gate_vma.vm_end     = 0xffff0000 + PAGE_SIZE;
    gate_vma.vm_page_prot   = PAGE_READONLY_EXEC;
    gate_vma.vm_flags   = VM_READ | VM_EXEC |
                  VM_MAYREAD | VM_MAYEXEC;
    return 0;
}
arch_initcall(gate_vma_init);

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
    return &gate_vma;
}

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
    return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
}

int in_gate_area_no_mm(unsigned long addr)
{
    return in_gate_area(NULL, addr);
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
    return (vma == &gate_vma) ? "[vectors]" : NULL;
}
#endif