process_32.c

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/*  linux/arch/sparc/kernel/process.c
 *
 *  Copyright (C) 1995, 2008 David S. Miller ([email protected])
 *  Copyright (C) 1996 Eddie C. Dost   ([email protected])
 */

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

#include <stdarg.h>

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/pm.h>
#include <linux/init.h>
#include <linux/slab.h>

#include <asm/auxio.h>
#include <asm/oplib.h>
#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/delay.h>
#include <asm/processor.h>
#include <asm/psr.h>
#include <asm/elf.h>
#include <asm/prom.h>
#include <asm/unistd.h>
#include <asm/setup.h>

/* 
 * Power management idle function 
 * Set in pm platform drivers (apc.c and pmc.c)
 */
void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);

/* 
 * Power-off handler instantiation for pm.h compliance
 * This is done via auxio, but could be used as a fallback
 * handler when auxio is not present-- unused for now...
 */
void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

/*
 * sysctl - toggle power-off restriction for serial console 
 * systems in machine_power_off()
 */
int scons_pwroff = 1;

extern void fpsave(unsigned long *, unsigned long *, void *, unsigned long *);

struct task_struct *last_task_used_math = NULL;
struct thread_info *current_set[NR_CPUS];

/*
 * the idle loop on a Sparc... ;)
 */
void cpu_idle(void)
{
    set_thread_flag(TIF_POLLING_NRFLAG);

    /* endless idle loop with no priority at all */
    for (;;) {
        while (!need_resched()) {
            if (pm_idle)
                (*pm_idle)();
            else
                cpu_relax();
        }
        schedule_preempt_disabled();
    }
}

/* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
void machine_halt(void)
{
    local_irq_enable();
    mdelay(8);
    local_irq_disable();
    prom_halt();
    panic("Halt failed!");
}

void machine_restart(char * cmd)
{
    char *p;
    
    local_irq_enable();
    mdelay(8);
    local_irq_disable();

    p = strchr (reboot_command, '\n');
    if (p) *p = 0;
    if (cmd)
        prom_reboot(cmd);
    if (*reboot_command)
        prom_reboot(reboot_command);
    prom_feval ("reset");
    panic("Reboot failed!");
}

void machine_power_off(void)
{
    if (auxio_power_register &&
        (strcmp(of_console_device->type, "serial") || scons_pwroff))
        *auxio_power_register |= AUXIO_POWER_OFF;
    machine_halt();
}

void show_regs(struct pt_regs *r)
{
    struct reg_window32 *rw = (struct reg_window32 *) r->u_regs[14];

        printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
           r->psr, r->pc, r->npc, r->y, print_tainted());
    printk("PC: <%pS>\n", (void *) r->pc);
    printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
           r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
           r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
    printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
           r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
           r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
    printk("RPC: <%pS>\n", (void *) r->u_regs[15]);

    printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
           rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
           rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
    printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
           rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
           rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
}

/*
 * The show_stack is an external API which we do not use ourselves.
 * The oops is printed in die_if_kernel.
 */
void show_stack(struct task_struct *tsk, unsigned long *_ksp)
{
    unsigned long pc, fp;
    unsigned long task_base;
    struct reg_window32 *rw;
    int count = 0;

    if (tsk != NULL)
        task_base = (unsigned long) task_stack_page(tsk);
    else
        task_base = (unsigned long) current_thread_info();

    fp = (unsigned long) _ksp;
    do {
        /* Bogus frame pointer? */
        if (fp < (task_base + sizeof(struct thread_info)) ||
            fp >= (task_base + (PAGE_SIZE << 1)))
            break;
        rw = (struct reg_window32 *) fp;
        pc = rw->ins[7];
        printk("[%08lx : ", pc);
        printk("%pS ] ", (void *) pc);
        fp = rw->ins[6];
    } while (++count < 16);
    printk("\n");
}

void dump_stack(void)
{
    unsigned long *ksp;

    __asm__ __volatile__("mov   %%fp, %0"
                 : "=r" (ksp));
    show_stack(current, ksp);
}

EXPORT_SYMBOL(dump_stack);

/*
 * Note: sparc64 has a pretty intricated thread_saved_pc, check it out.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
    return task_thread_info(tsk)->kpc;
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
#ifndef CONFIG_SMP
    if(last_task_used_math == current) {
#else
    if (test_thread_flag(TIF_USEDFPU)) {
#endif
        /* Keep process from leaving FPU in a bogon state. */
        put_psr(get_psr() | PSR_EF);
        fpsave(&current->thread.float_regs[0], &current->thread.fsr,
               &current->thread.fpqueue[0], &current->thread.fpqdepth);
#ifndef CONFIG_SMP
        last_task_used_math = NULL;
#else
        clear_thread_flag(TIF_USEDFPU);
#endif
    }
}

void flush_thread(void)
{
    current_thread_info()->w_saved = 0;

#ifndef CONFIG_SMP
    if(last_task_used_math == current) {
#else
    if (test_thread_flag(TIF_USEDFPU)) {
#endif
        /* Clean the fpu. */
        put_psr(get_psr() | PSR_EF);
        fpsave(&current->thread.float_regs[0], &current->thread.fsr,
               &current->thread.fpqueue[0], &current->thread.fpqdepth);
#ifndef CONFIG_SMP
        last_task_used_math = NULL;
#else
        clear_thread_flag(TIF_USEDFPU);
#endif
    }

    /* This task is no longer a kernel thread. */
    if (current->thread.flags & SPARC_FLAG_KTHREAD) {
        current->thread.flags &= ~SPARC_FLAG_KTHREAD;

        /* We must fixup kregs as well. */
        /* XXX This was not fixed for ti for a while, worked. Unused? */
        current->thread.kregs = (struct pt_regs *)
            (task_stack_page(current) + (THREAD_SIZE - TRACEREG_SZ));
    }
}

static inline struct sparc_stackf __user *
clone_stackframe(struct sparc_stackf __user *dst,
         struct sparc_stackf __user *src)
{
    unsigned long size, fp;
    struct sparc_stackf *tmp;
    struct sparc_stackf __user *sp;

    if (get_user(tmp, &src->fp))
        return NULL;

    fp = (unsigned long) tmp;
    size = (fp - ((unsigned long) src));
    fp = (unsigned long) dst;
    sp = (struct sparc_stackf __user *)(fp - size); 

    /* do_fork() grabs the parent semaphore, we must release it
     * temporarily so we can build the child clone stack frame
     * without deadlocking.
     */
    if (__copy_user(sp, src, size))
        sp = NULL;
    else if (put_user(fp, &sp->fp))
        sp = NULL;

    return sp;
}

asmlinkage int sparc_do_fork(unsigned long clone_flags,
                             unsigned long stack_start,
                             struct pt_regs *regs,
                             unsigned long stack_size)
{
    unsigned long parent_tid_ptr, child_tid_ptr;
    unsigned long orig_i1 = regs->u_regs[UREG_I1];
    long ret;

    parent_tid_ptr = regs->u_regs[UREG_I2];
    child_tid_ptr = regs->u_regs[UREG_I4];

    ret = do_fork(clone_flags, stack_start,
              regs, stack_size,
              (int __user *) parent_tid_ptr,
              (int __user *) child_tid_ptr);

    /* If we get an error and potentially restart the system
     * call, we're screwed because copy_thread() clobbered
     * the parent's %o1.  So detect that case and restore it
     * here.
     */
    if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
        regs->u_regs[UREG_I1] = orig_i1;

    return ret;
}

/* Copy a Sparc thread.  The fork() return value conventions
 * under SunOS are nothing short of bletcherous:
 * Parent -->  %o0 == childs  pid, %o1 == 0
 * Child  -->  %o0 == parents pid, %o1 == 1
 *
 * NOTE: We have a separate fork kpsr/kwim because
 *       the parent could change these values between
 *       sys_fork invocation and when we reach here
 *       if the parent should sleep while trying to
 *       allocate the task_struct and kernel stack in
 *       do_fork().
 * XXX See comment above sys_vfork in sparc64. todo.
 */
extern void ret_from_fork(void);

int copy_thread(unsigned long clone_flags, unsigned long sp,
        unsigned long unused,
        struct task_struct *p, struct pt_regs *regs)
{
    struct thread_info *ti = task_thread_info(p);
    struct pt_regs *childregs;
    char *new_stack;

#ifndef CONFIG_SMP
    if(last_task_used_math == current) {
#else
    if (test_thread_flag(TIF_USEDFPU)) {
#endif
        put_psr(get_psr() | PSR_EF);
        fpsave(&p->thread.float_regs[0], &p->thread.fsr,
               &p->thread.fpqueue[0], &p->thread.fpqdepth);
    }

    /*
     *  p->thread_info         new_stack   childregs
     *  !                      !           !             {if(PSR_PS) }
     *  V                      V (stk.fr.) V  (pt_regs)  { (stk.fr.) }
     *  +----- - - - - - ------+===========+============={+==========}+
     */
    new_stack = task_stack_page(p) + THREAD_SIZE;
    if (regs->psr & PSR_PS)
        new_stack -= STACKFRAME_SZ;
    new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
    memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
    childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);

    /*
     * A new process must start with interrupts closed in 2.5,
     * because this is how Mingo's scheduler works (see schedule_tail
     * and finish_arch_switch). If we do not do it, a timer interrupt hits
     * before we unlock, attempts to re-take the rq->lock, and then we die.
     * Thus, kpsr|=PSR_PIL.
     */
    ti->ksp = (unsigned long) new_stack;
    ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
    ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
    ti->kwim = current->thread.fork_kwim;

    if(regs->psr & PSR_PS) {
        extern struct pt_regs fake_swapper_regs;

        p->thread.kregs = &fake_swapper_regs;
        new_stack += STACKFRAME_SZ + TRACEREG_SZ;
        childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
        p->thread.flags |= SPARC_FLAG_KTHREAD;
        p->thread.current_ds = KERNEL_DS;
        memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
        childregs->u_regs[UREG_G6] = (unsigned long) ti;
    } else {
        p->thread.kregs = childregs;
        childregs->u_regs[UREG_FP] = sp;
        p->thread.flags &= ~SPARC_FLAG_KTHREAD;
        p->thread.current_ds = USER_DS;

        if (sp != regs->u_regs[UREG_FP]) {
            struct sparc_stackf __user *childstack;
            struct sparc_stackf __user *parentstack;

            /*
             * This is a clone() call with supplied user stack.
             * Set some valid stack frames to give to the child.
             */
            childstack = (struct sparc_stackf __user *)
                (sp & ~0xfUL);
            parentstack = (struct sparc_stackf __user *)
                regs->u_regs[UREG_FP];

#if 0
            printk("clone: parent stack:\n");
            show_stackframe(parentstack);
#endif

            childstack = clone_stackframe(childstack, parentstack);
            if (!childstack)
                return -EFAULT;

#if 0
            printk("clone: child stack:\n");
            show_stackframe(childstack);
#endif

            childregs->u_regs[UREG_FP] = (unsigned long)childstack;
        }
    }

#ifdef CONFIG_SMP
    /* FPU must be disabled on SMP. */
    childregs->psr &= ~PSR_EF;
    clear_tsk_thread_flag(p, TIF_USEDFPU);
#endif

    /* Set the return value for the child. */
    childregs->u_regs[UREG_I0] = current->pid;
    childregs->u_regs[UREG_I1] = 1;

    /* Set the return value for the parent. */
    regs->u_regs[UREG_I1] = 0;

    if (clone_flags & CLONE_SETTLS)
        childregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];

    return 0;
}

/*
 * fill in the fpu structure for a core dump.
 */
int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
{
    if (used_math()) {
        memset(fpregs, 0, sizeof(*fpregs));
        fpregs->pr_q_entrysize = 8;
        return 1;
    }
#ifdef CONFIG_SMP
    if (test_thread_flag(TIF_USEDFPU)) {
        put_psr(get_psr() | PSR_EF);
        fpsave(&current->thread.float_regs[0], &current->thread.fsr,
               &current->thread.fpqueue[0], &current->thread.fpqdepth);
        if (regs != NULL) {
            regs->psr &= ~(PSR_EF);
            clear_thread_flag(TIF_USEDFPU);
        }
    }
#else
    if (current == last_task_used_math) {
        put_psr(get_psr() | PSR_EF);
        fpsave(&current->thread.float_regs[0], &current->thread.fsr,
               &current->thread.fpqueue[0], &current->thread.fpqdepth);
        if (regs != NULL) {
            regs->psr &= ~(PSR_EF);
            last_task_used_math = NULL;
        }
    }
#endif
    memcpy(&fpregs->pr_fr.pr_regs[0],
           &current->thread.float_regs[0],
           (sizeof(unsigned long) * 32));
    fpregs->pr_fsr = current->thread.fsr;
    fpregs->pr_qcnt = current->thread.fpqdepth;
    fpregs->pr_q_entrysize = 8;
    fpregs->pr_en = 1;
    if(fpregs->pr_qcnt != 0) {
        memcpy(&fpregs->pr_q[0],
               &current->thread.fpqueue[0],
               sizeof(struct fpq) * fpregs->pr_qcnt);
    }
    /* Zero out the rest. */
    memset(&fpregs->pr_q[fpregs->pr_qcnt], 0,
           sizeof(struct fpq) * (32 - fpregs->pr_qcnt));
    return 1;
}

/*
 * sparc_execve() executes a new program after the asm stub has set
 * things up for us.  This should basically do what I want it to.
 */
asmlinkage int sparc_execve(struct pt_regs *regs)
{
    int error, base = 0;
    struct filename *filename;

    /* Check for indirect call. */
    if(regs->u_regs[UREG_G1] == 0)
        base = 1;

    filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
    error = PTR_ERR(filename);
    if(IS_ERR(filename))
        goto out;
    error = do_execve(filename->name,
              (const char __user *const  __user *)
              regs->u_regs[base + UREG_I1],
              (const char __user *const  __user *)
              regs->u_regs[base + UREG_I2],
              regs);
    putname(filename);
out:
    return error;
}

/*
 * This is the mechanism for creating a new kernel thread.
 *
 * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 * who haven't done an "execve()") should use this: it will work within
 * a system call from a "real" process, but the process memory space will
 * not be freed until both the parent and the child have exited.
 */
pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
    long retval;

    __asm__ __volatile__("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
                 "mov %5, %%g3\n\t"    /* and arg. */
                 "mov %1, %%g1\n\t"
                 "mov %2, %%o0\n\t"    /* Clone flags. */
                 "mov 0, %%o1\n\t"     /* usp arg == 0 */
                 "t 0x10\n\t"          /* Linux/Sparc clone(). */
                 "cmp %%o1, 0\n\t"
                 "be 1f\n\t"           /* The parent, just return. */
                 " nop\n\t"            /* Delay slot. */
                 "jmpl %%g2, %%o7\n\t" /* Call the function. */
                 " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
                 "mov %3, %%g1\n\t"
                 "t 0x10\n\t"          /* Linux/Sparc exit(). */
                 /* Notreached by child. */
                 "1: mov %%o0, %0\n\t" :
                 "=r" (retval) :
                 "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
                 "i" (__NR_exit),  "r" (fn), "r" (arg) :
                 "g1", "g2", "g3", "o0", "o1", "memory", "cc");
    return retval;
}
EXPORT_SYMBOL(kernel_thread);

unsigned long get_wchan(struct task_struct *task)
{
    unsigned long pc, fp, bias = 0;
    unsigned long task_base = (unsigned long) task;
        unsigned long ret = 0;
    struct reg_window32 *rw;
    int count = 0;

    if (!task || task == current ||
            task->state == TASK_RUNNING)
        goto out;

    fp = task_thread_info(task)->ksp + bias;
    do {
        /* Bogus frame pointer? */
        if (fp < (task_base + sizeof(struct thread_info)) ||
            fp >= (task_base + (2 * PAGE_SIZE)))
            break;
        rw = (struct reg_window32 *) fp;
        pc = rw->ins[7];
        if (!in_sched_functions(pc)) {
            ret = pc;
            goto out;
        }
        fp = rw->ins[6] + bias;
    } while (++count < 16);

out:
    return ret;
}