process.c

Go to the documentation of this file.

/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * 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 <linux/sched.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/fs.h>
#include <linux/pm.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/reboot.h>
#include <linux/tick.h>
#include <linux/uaccess.h>
#include <linux/unistd.h>

#include <asm/sysreg.h>
#include <asm/ocd.h>
#include <asm/syscalls.h>

#include <mach/pm.h>

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

/*
 * This file handles the architecture-dependent parts of process handling..
 */

void cpu_idle(void)
{
    /* endless idle loop with no priority at all */
    while (1) {
        tick_nohz_idle_enter();
        rcu_idle_enter();
        while (!need_resched())
            cpu_idle_sleep();
        rcu_idle_exit();
        tick_nohz_idle_exit();
        schedule_preempt_disabled();
    }
}

void machine_halt(void)
{
    /*
     * Enter Stop mode. The 32 kHz oscillator will keep running so
     * the RTC will keep the time properly and the system will
     * boot quickly.
     */
    asm volatile("sleep 3\n\t"
             "sub pc, -2");
}

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

void machine_restart(char *cmd)
{
    ocd_write(DC, (1 << OCD_DC_DBE_BIT));
    ocd_write(DC, (1 << OCD_DC_RES_BIT));
    while (1) ;
}

/*
 * PC is actually discarded when returning from a system call -- the
 * return address must be stored in LR. This function will make sure
 * LR points to do_exit before starting the thread.
 *
 * Also, when returning from fork(), r12 is 0, so we must copy the
 * argument as well.
 *
 *  r0 : The argument to the main thread function
 *  r1 : The address of do_exit
 *  r2 : The address of the main thread function
 */
asmlinkage extern void kernel_thread_helper(void);
__asm__("   .type   kernel_thread_helper, @function\n"
    "kernel_thread_helper:\n"
    "   mov r12, r0\n"
    "   mov lr, r2\n"
    "   mov pc, r1\n"
    "   .size   kernel_thread_helper, . - kernel_thread_helper");

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

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

    regs.r0 = (unsigned long)arg;
    regs.r1 = (unsigned long)fn;
    regs.r2 = (unsigned long)do_exit;
    regs.lr = (unsigned long)kernel_thread_helper;
    regs.pc = (unsigned long)kernel_thread_helper;
    regs.sr = MODE_SUPERVISOR;

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

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

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

void release_thread(struct task_struct *dead_task)
{
    /* do nothing */
}

static void dump_mem(const char *str, const char *log_lvl,
             unsigned long bottom, unsigned long top)
{
    unsigned long p;
    int i;

    printk("%s%s(0x%08lx to 0x%08lx)\n", log_lvl, str, bottom, top);

    for (p = bottom & ~31; p < top; ) {
        printk("%s%04lx: ", log_lvl, p & 0xffff);

        for (i = 0; i < 8; i++, p += 4) {
            unsigned int val;

            if (p < bottom || p >= top)
                printk("         ");
            else {
                if (__get_user(val, (unsigned int __user *)p)) {
                    printk("\n");
                    goto out;
                }
                printk("%08x ", val);
            }
        }
        printk("\n");
    }

out:
    return;
}

static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
{
    return (p > (unsigned long)tinfo)
        && (p < (unsigned long)tinfo + THREAD_SIZE - 3);
}

#ifdef CONFIG_FRAME_POINTER
static void show_trace_log_lvl(struct task_struct *tsk, unsigned long *sp,
                   struct pt_regs *regs, const char *log_lvl)
{
    unsigned long lr, fp;
    struct thread_info *tinfo;

    if (regs)
        fp = regs->r7;
    else if (tsk == current)
        asm("mov %0, r7" : "=r"(fp));
    else
        fp = tsk->thread.cpu_context.r7;

    /*
     * Walk the stack as long as the frame pointer (a) is within
     * the kernel stack of the task, and (b) it doesn't move
     * downwards.
     */
    tinfo = task_thread_info(tsk);
    printk("%sCall trace:\n", log_lvl);
    while (valid_stack_ptr(tinfo, fp)) {
        unsigned long new_fp;

        lr = *(unsigned long *)fp;
#ifdef CONFIG_KALLSYMS
        printk("%s [<%08lx>] ", log_lvl, lr);
#else
        printk(" [<%08lx>] ", lr);
#endif
        print_symbol("%s\n", lr);

        new_fp = *(unsigned long *)(fp + 4);
        if (new_fp <= fp)
            break;
        fp = new_fp;
    }
    printk("\n");
}
#else
static void show_trace_log_lvl(struct task_struct *tsk, unsigned long *sp,
                   struct pt_regs *regs, const char *log_lvl)
{
    unsigned long addr;

    printk("%sCall trace:\n", log_lvl);

    while (!kstack_end(sp)) {
        addr = *sp++;
        if (kernel_text_address(addr)) {
#ifdef CONFIG_KALLSYMS
            printk("%s [<%08lx>] ", log_lvl, addr);
#else
            printk(" [<%08lx>] ", addr);
#endif
            print_symbol("%s\n", addr);
        }
    }
    printk("\n");
}
#endif

void show_stack_log_lvl(struct task_struct *tsk, unsigned long sp,
            struct pt_regs *regs, const char *log_lvl)
{
    struct thread_info *tinfo;

    if (sp == 0) {
        if (tsk)
            sp = tsk->thread.cpu_context.ksp;
        else
            sp = (unsigned long)&tinfo;
    }
    if (!tsk)
        tsk = current;

    tinfo = task_thread_info(tsk);

    if (valid_stack_ptr(tinfo, sp)) {
        dump_mem("Stack: ", log_lvl, sp,
             THREAD_SIZE + (unsigned long)tinfo);
        show_trace_log_lvl(tsk, (unsigned long *)sp, regs, log_lvl);
    }
}

void show_stack(struct task_struct *tsk, unsigned long *stack)
{
    show_stack_log_lvl(tsk, (unsigned long)stack, NULL, "");
}

void dump_stack(void)
{
    unsigned long stack;

    show_trace_log_lvl(current, &stack, NULL, "");
}
EXPORT_SYMBOL(dump_stack);

static const char *cpu_modes[] = {
    "Application", "Supervisor", "Interrupt level 0", "Interrupt level 1",
    "Interrupt level 2", "Interrupt level 3", "Exception", "NMI"
};

void show_regs_log_lvl(struct pt_regs *regs, const char *log_lvl)
{
    unsigned long sp = regs->sp;
    unsigned long lr = regs->lr;
    unsigned long mode = (regs->sr & MODE_MASK) >> MODE_SHIFT;

    if (!user_mode(regs)) {
        sp = (unsigned long)regs + FRAME_SIZE_FULL;

        printk("%s", log_lvl);
        print_symbol("PC is at %s\n", instruction_pointer(regs));
        printk("%s", log_lvl);
        print_symbol("LR is at %s\n", lr);
    }

    printk("%spc : [<%08lx>]    lr : [<%08lx>]    %s\n"
           "%ssp : %08lx  r12: %08lx  r11: %08lx\n",
           log_lvl, instruction_pointer(regs), lr, print_tainted(),
           log_lvl, sp, regs->r12, regs->r11);
    printk("%sr10: %08lx  r9 : %08lx  r8 : %08lx\n",
           log_lvl, regs->r10, regs->r9, regs->r8);
    printk("%sr7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
           log_lvl, regs->r7, regs->r6, regs->r5, regs->r4);
    printk("%sr3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
           log_lvl, regs->r3, regs->r2, regs->r1, regs->r0);
    printk("%sFlags: %c%c%c%c%c\n", log_lvl,
           regs->sr & SR_Q ? 'Q' : 'q',
           regs->sr & SR_V ? 'V' : 'v',
           regs->sr & SR_N ? 'N' : 'n',
           regs->sr & SR_Z ? 'Z' : 'z',
           regs->sr & SR_C ? 'C' : 'c');
    printk("%sMode bits: %c%c%c%c%c%c%c%c%c%c\n", log_lvl,
           regs->sr & SR_H ? 'H' : 'h',
           regs->sr & SR_J ? 'J' : 'j',
           regs->sr & SR_DM ? 'M' : 'm',
           regs->sr & SR_D ? 'D' : 'd',
           regs->sr & SR_EM ? 'E' : 'e',
           regs->sr & SR_I3M ? '3' : '.',
           regs->sr & SR_I2M ? '2' : '.',
           regs->sr & SR_I1M ? '1' : '.',
           regs->sr & SR_I0M ? '0' : '.',
           regs->sr & SR_GM ? 'G' : 'g');
    printk("%sCPU Mode: %s\n", log_lvl, cpu_modes[mode]);
    printk("%sProcess: %s [%d] (task: %p thread: %p)\n",
           log_lvl, current->comm, current->pid, current,
           task_thread_info(current));
}

void show_regs(struct pt_regs *regs)
{
    unsigned long sp = regs->sp;

    if (!user_mode(regs))
        sp = (unsigned long)regs + FRAME_SIZE_FULL;

    show_regs_log_lvl(regs, "");
    show_trace_log_lvl(current, (unsigned long *)sp, regs, "");
}
EXPORT_SYMBOL(show_regs);

/* Fill in the fpu structure for a core dump. This is easy -- we don't have any */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
    /* Not valid */
    return 0;
}

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;

    childregs = ((struct pt_regs *)(THREAD_SIZE + (unsigned long)task_stack_page(p))) - 1;
    *childregs = *regs;

    if (user_mode(regs))
        childregs->sp = usp;
    else
        childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

    childregs->r12 = 0; /* Set return value for child */

    p->thread.cpu_context.sr = MODE_SUPERVISOR | SR_GM;
    p->thread.cpu_context.ksp = (unsigned long)childregs;
    p->thread.cpu_context.pc = (unsigned long)ret_from_fork;

    clear_tsk_thread_flag(p, TIF_DEBUG);
    if ((clone_flags & CLONE_PTRACE) && test_thread_flag(TIF_DEBUG))
        ocd_enable(p);

    return 0;
}

/* r12-r8 are dummy parameters to force the compiler to use the stack */
asmlinkage int sys_fork(struct pt_regs *regs)
{
    return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
}

asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
        void __user *parent_tidptr, void __user *child_tidptr,
        struct pt_regs *regs)
{
    if (!newsp)
        newsp = regs->sp;
    return do_fork(clone_flags, newsp, regs, 0, parent_tidptr,
            child_tidptr);
}

asmlinkage int sys_vfork(struct pt_regs *regs)
{
    return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs,
               0, NULL, NULL);
}

asmlinkage int sys_execve(const char __user *ufilename,
              const char __user *const __user *uargv,
              const char __user *const __user *uenvp,
              struct pt_regs *regs)
{
    int error;
    struct filename *filename;

    filename = getname(ufilename);
    error = PTR_ERR(filename);
    if (IS_ERR(filename))
        goto out;

    error = do_execve(filename->name, uargv, uenvp, regs);
    putname(filename);

out:
    return error;
}


/*
 * This function is supposed to answer the question "who called
 * schedule()?"
 */
unsigned long get_wchan(struct task_struct *p)
{
    unsigned long pc;
    unsigned long stack_page;

    if (!p || p == current || p->state == TASK_RUNNING)
        return 0;

    stack_page = (unsigned long)task_stack_page(p);
    BUG_ON(!stack_page);

    /*
     * The stored value of PC is either the address right after
     * the call to __switch_to() or ret_from_fork.
     */
    pc = thread_saved_pc(p);
    if (in_sched_functions(pc)) {
#ifdef CONFIG_FRAME_POINTER
        unsigned long fp = p->thread.cpu_context.r7;
        BUG_ON(fp < stack_page || fp > (THREAD_SIZE + stack_page));
        pc = *(unsigned long *)fp;
#else
        /*
         * We depend on the frame size of schedule here, which
         * is actually quite ugly. It might be possible to
         * determine the frame size automatically at build
         * time by doing this:
         *   - compile sched.c
         *   - disassemble the resulting sched.o
         *   - look for 'sub sp,??' shortly after '<schedule>:'
         */
        unsigned long sp = p->thread.cpu_context.ksp + 16;
        BUG_ON(sp < stack_page || sp > (THREAD_SIZE + stack_page));
        pc = *(unsigned long *)sp;
#endif
    }

    return pc;
}