/*  arch/sparc64/kernel/process.c
 *
 *  Copyright (C) 1995, 1996, 2008 David S. Miller (davem@davemloft.net)
 *  Copyright (C) 1996       Eddie C. Dost   (ecd@skynet.be)
 *  Copyright (C) 1997, 1998 Jakub Jelinek   (jj@sunsite.mff.cuni.cz)
 */

/*
 * 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/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/compat.h>
#include <linux/tick.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/sysrq.h>

#include <asm/oplib.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/pstate.h>
#include <asm/elf.h>
#include <asm/fpumacro.h>
#include <asm/head.h>
#include <asm/cpudata.h>
#include <asm/mmu_context.h>
#include <asm/unistd.h>
#include <asm/hypervisor.h>
#include <asm/sstate.h>
#include <asm/reboot.h>
#include <asm/syscalls.h>
#include <asm/irq_regs.h>
#include <asm/smp.h>

#include "kstack.h"

static void sparc64_yield(int cpu)
{
        if (tlb_type != hypervisor)
                return;

        clear_thread_flag(TIF_POLLING_NRFLAG);
        smp_mb__after_clear_bit();

        while (!need_resched() && !cpu_is_offline(cpu)) {
                unsigned long pstate;

                /* Disable interrupts. */
                __asm__ __volatile__(
                        "rdpr %%pstate, %0\n\t"
                        "andn %0, %1, %0\n\t"
                        "wrpr %0, %%g0, %%pstate"
                        : "=&r" (pstate)
                        : "i" (PSTATE_IE));

                if (!need_resched() && !cpu_is_offline(cpu))
                        sun4v_cpu_yield();

                /* Re-enable interrupts. */
                __asm__ __volatile__(
                        "rdpr %%pstate, %0\n\t"
                        "or %0, %1, %0\n\t"
                        "wrpr %0, %%g0, %%pstate"
                        : "=&r" (pstate)
                        : "i" (PSTATE_IE));
        }

        set_thread_flag(TIF_POLLING_NRFLAG);
}

/* The idle loop on sparc64. */
void cpu_idle(void)
{
        int cpu = smp_processor_id();

        set_thread_flag(TIF_POLLING_NRFLAG);

        while(1) {
                tick_nohz_stop_sched_tick(1);

                while (!need_resched() && !cpu_is_offline(cpu))
                        sparc64_yield(cpu);

                tick_nohz_restart_sched_tick();

                preempt_enable_no_resched();

#ifdef CONFIG_HOTPLUG_CPU
                if (cpu_is_offline(cpu))
                        cpu_play_dead();
#endif

                schedule();
                preempt_disable();
        }
}

void machine_halt(void)
{
        sstate_halt();
        prom_halt();
        panic("Halt failed!");
}

void machine_alt_power_off(void)
{
        sstate_poweroff();
        prom_halt_power_off();
        panic("Power-off failed!");
}

void machine_restart(char * cmd)
{
        char *p;
        
        sstate_reboot();
        p = strchr (reboot_command, '\n');
        if (p) *p = 0;
        if (cmd)
                prom_reboot(cmd);
        if (*reboot_command)
                prom_reboot(reboot_command);
        prom_reboot("");
        panic("Reboot failed!");
}

#ifdef CONFIG_COMPAT
static void show_regwindow32(struct pt_regs *regs)
{
        struct reg_window32 __user *rw;
        struct reg_window32 r_w;
        mm_segment_t old_fs;
        
        __asm__ __volatile__ ("flushw");
        rw = compat_ptr((unsigned)regs->u_regs[14]);
        old_fs = get_fs();
        set_fs (USER_DS);
        if (copy_from_user (&r_w, rw, sizeof(r_w))) {
                set_fs (old_fs);
                return;
        }

        set_fs (old_fs);                        
        printk("l0: %08x l1: %08x l2: %08x l3: %08x "
               "l4: %08x l5: %08x l6: %08x l7: %08x\n",
               r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3],
               r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]);
        printk("i0: %08x i1: %08x i2: %08x i3: %08x "
               "i4: %08x i5: %08x i6: %08x i7: %08x\n",
               r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3],
               r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]);
}
#else
#define show_regwindow32(regs)  do { } while (0)
#endif

static void show_regwindow(struct pt_regs *regs)
{
        struct reg_window __user *rw;
        struct reg_window *rwk;
        struct reg_window r_w;
        mm_segment_t old_fs;

        if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) {
                __asm__ __volatile__ ("flushw");
                rw = (struct reg_window __user *)
                        (regs->u_regs[14] + STACK_BIAS);
                rwk = (struct reg_window *)
                        (regs->u_regs[14] + STACK_BIAS);
                if (!(regs->tstate & TSTATE_PRIV)) {
                        old_fs = get_fs();
                        set_fs (USER_DS);
                        if (copy_from_user (&r_w, rw, sizeof(r_w))) {
                                set_fs (old_fs);
                                return;
                        }
                        rwk = &r_w;
                        set_fs (old_fs);                        
                }
        } else {
                show_regwindow32(regs);
                return;
        }
        printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n",
               rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]);
        printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
               rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]);
        printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n",
               rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]);
        printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n",
               rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]);
        if (regs->tstate & TSTATE_PRIV)
                printk("I7: <%pS>\n", (void *) rwk->ins[7]);
}

void show_regs(struct pt_regs *regs)
{
        printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x    %s\n", regs->tstate,
               regs->tpc, regs->tnpc, regs->y, print_tainted());
        printk("TPC: <%pS>\n", (void *) regs->tpc);
        printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n",
               regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
               regs->u_regs[3]);
        printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n",
               regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
               regs->u_regs[7]);
        printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n",
               regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
               regs->u_regs[11]);
        printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n",
               regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
               regs->u_regs[15]);
        printk("RPC: <%pS>\n", (void *) regs->u_regs[15]);
        show_regwindow(regs);
}

struct global_reg_snapshot global_reg_snapshot[NR_CPUS];
static DEFINE_SPINLOCK(global_reg_snapshot_lock);

static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
                              int this_cpu)
{
        flushw_all();

        global_reg_snapshot[this_cpu].tstate = regs->tstate;
        global_reg_snapshot[this_cpu].tpc = regs->tpc;
        global_reg_snapshot[this_cpu].tnpc = regs->tnpc;
        global_reg_snapshot[this_cpu].o7 = regs->u_regs[UREG_I7];

        if (regs->tstate & TSTATE_PRIV) {
                struct thread_info *tp = current_thread_info();
                struct reg_window *rw;

                rw = (struct reg_window *)
                        (regs->u_regs[UREG_FP] + STACK_BIAS);
                if (kstack_valid(tp, (unsigned long) rw)) {
                        global_reg_snapshot[this_cpu].i7 = rw->ins[7];
                        rw = (struct reg_window *)
                                (rw->ins[6] + STACK_BIAS);
                        if (kstack_valid(tp, (unsigned long) rw))
                                global_reg_snapshot[this_cpu].rpc = rw->ins[7];
                }
        } else {
                global_reg_snapshot[this_cpu].i7 = 0;
                global_reg_snapshot[this_cpu].rpc = 0;
        }
        global_reg_snapshot[this_cpu].thread = tp;
}

/* In order to avoid hangs we do not try to synchronize with the
 * global register dump client cpus.  The last store they make is to
 * the thread pointer, so do a short poll waiting for that to become
 * non-NULL.
 */
static void __global_reg_poll(struct global_reg_snapshot *gp)
{
        int limit = 0;

        while (!gp->thread && ++limit < 100) {
                barrier();
                udelay(1);
        }
}

void __trigger_all_cpu_backtrace(void)
{
        struct thread_info *tp = current_thread_info();
        struct pt_regs *regs = get_irq_regs();
        unsigned long flags;
        int this_cpu, cpu;

        if (!regs)
                regs = tp->kregs;

        spin_lock_irqsave(&global_reg_snapshot_lock, flags);

        memset(global_reg_snapshot, 0, sizeof(global_reg_snapshot));

        this_cpu = raw_smp_processor_id();

        __global_reg_self(tp, regs, this_cpu);

        smp_fetch_global_regs();

        for_each_online_cpu(cpu) {
                struct global_reg_snapshot *gp = &global_reg_snapshot[cpu];
                struct thread_info *tp;

                __global_reg_poll(gp);

                tp = gp->thread;
                printk("%c CPU[%3d]: TSTATE[%016lx] TPC[%016lx] TNPC[%016lx] TASK[%s:%d]\n",
                       (cpu == this_cpu ? '*' : ' '), cpu,
                       gp->tstate, gp->tpc, gp->tnpc,
                       ((tp && tp->task) ? tp->task->comm : "NULL"),
                       ((tp && tp->task) ? tp->task->pid : -1));

                if (gp->tstate & TSTATE_PRIV) {
                        printk("             TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n",
                               (void *) gp->tpc,
                               (void *) gp->o7,
                               (void *) gp->i7,
                               (void *) gp->rpc);
                } else {
                        printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
                               gp->tpc, gp->o7, gp->i7, gp->rpc);
                }
        }

        memset(global_reg_snapshot, 0, sizeof(global_reg_snapshot));

        spin_unlock_irqrestore(&global_reg_snapshot_lock, flags);
}

#ifdef CONFIG_MAGIC_SYSRQ

static void sysrq_handle_globreg(int key, struct tty_struct *tty)
{
        __trigger_all_cpu_backtrace();
}

static struct sysrq_key_op sparc_globalreg_op = {
        .handler        = sysrq_handle_globreg,
        .help_msg       = "Globalregs",
        .action_msg     = "Show Global CPU Regs",
};

static int __init sparc_globreg_init(void)
{
        return register_sysrq_key('y', &sparc_globalreg_op);
}

core_initcall(sparc_globreg_init);

#endif

unsigned long thread_saved_pc(struct task_struct *tsk)
{
        struct thread_info *ti = task_thread_info(tsk);
        unsigned long ret = 0xdeadbeefUL;
        
        if (ti && ti->ksp) {
                unsigned long *sp;
                sp = (unsigned long *)(ti->ksp + STACK_BIAS);
                if (((unsigned long)sp & (sizeof(long) - 1)) == 0UL &&
                    sp[14]) {
                        unsigned long *fp;
                        fp = (unsigned long *)(sp[14] + STACK_BIAS);
                        if (((unsigned long)fp & (sizeof(long) - 1)) == 0UL)
                                ret = fp[15];
                }
        }
        return ret;
}

/* Free current thread data structures etc.. */
void exit_thread(void)
{
        struct thread_info *t = current_thread_info();

        if (t->utraps) {
                if (t->utraps[0] < 2)
                        kfree (t->utraps);
                else
                        t->utraps[0]--;
        }

        if (test_and_clear_thread_flag(TIF_PERFCTR)) {
                t->user_cntd0 = t->user_cntd1 = NULL;
                t->pcr_reg = 0;
                write_pcr(0);
        }
}

void flush_thread(void)
{
        struct thread_info *t = current_thread_info();
        struct mm_struct *mm;

        if (test_ti_thread_flag(t, TIF_ABI_PENDING)) {
                clear_ti_thread_flag(t, TIF_ABI_PENDING);
                if (test_ti_thread_flag(t, TIF_32BIT))
                        clear_ti_thread_flag(t, TIF_32BIT);
                else
                        set_ti_thread_flag(t, TIF_32BIT);
        }

        mm = t->task->mm;
        if (mm)
                tsb_context_switch(mm);

        set_thread_wsaved(0);

        /* Turn off performance counters if on. */
        if (test_and_clear_thread_flag(TIF_PERFCTR)) {
                t->user_cntd0 = t->user_cntd1 = NULL;
                t->pcr_reg = 0;
                write_pcr(0);
        }

        /* Clear FPU register state. */
        t->fpsaved[0] = 0;
        
        if (get_thread_current_ds() != ASI_AIUS)
                set_fs(USER_DS);
}

/* It's a bit more tricky when 64-bit tasks are involved... */
static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
{
        unsigned long fp, distance, rval;

        if (!(test_thread_flag(TIF_32BIT))) {
                csp += STACK_BIAS;
                psp += STACK_BIAS;
                __get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
                fp += STACK_BIAS;
        } else
                __get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));

        /* Now 8-byte align the stack as this is mandatory in the
         * Sparc ABI due to how register windows work.  This hides
         * the restriction from thread libraries etc.  -DaveM
         */
        csp &= ~7UL;

        distance = fp - psp;
        rval = (csp - distance);
        if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
                rval = 0;
        else if (test_thread_flag(TIF_32BIT)) {
                if (put_user(((u32)csp),
                             &(((struct reg_window32 __user *)rval)->ins[6])))
                        rval = 0;
        } else {
                if (put_user(((u64)csp - STACK_BIAS),
                             &(((struct reg_window __user *)rval)->ins[6])))
                        rval = 0;
                else
                        rval = rval - STACK_BIAS;
        }

        return rval;
}

/* Standard stuff. */
static inline void shift_window_buffer(int first_win, int last_win,
                                       struct thread_info *t)
{
        int i;

        for (i = first_win; i < last_win; i++) {
                t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1];
                memcpy(&t->reg_window[i], &t->reg_window[i+1],
                       sizeof(struct reg_window));
        }
}

void synchronize_user_stack(void)
{
        struct thread_info *t = current_thread_info();
        unsigned long window;

        flush_user_windows();
        if ((window = get_thread_wsaved()) != 0) {
                int winsize = sizeof(struct reg_window);
                int bias = 0;

                if (test_thread_flag(TIF_32BIT))
                        winsize = sizeof(struct reg_window32);
                else
                        bias = STACK_BIAS;

                window -= 1;
                do {
                        unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
                        struct reg_window *rwin = &t->reg_window[window];

                        if (!copy_to_user((char __user *)sp, rwin, winsize)) {
                                shift_window_buffer(window, get_thread_wsaved() - 1, t);
                                set_thread_wsaved(get_thread_wsaved() - 1);
                        }
                } while (window--);
        }
}

static void stack_unaligned(unsigned long sp)
{
        siginfo_t info;

        info.si_signo = SIGBUS;
        info.si_errno = 0;
        info.si_code = BUS_ADRALN;
        info.si_addr = (void __user *) sp;
        info.si_trapno = 0;
        force_sig_info(SIGBUS, &info, current);
}

void fault_in_user_windows(void)
{
        struct thread_info *t = current_thread_info();
        unsigned long window;
        int winsize = sizeof(struct reg_window);
        int bias = 0;

        if (test_thread_flag(TIF_32BIT))
                winsize = sizeof(struct reg_window32);
        else
                bias = STACK_BIAS;

        flush_user_windows();
        window = get_thread_wsaved();

        if (likely(window != 0)) {
                window -= 1;
                do {
                        unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
                        struct reg_window *rwin = &t->reg_window[window];

                        if (unlikely(sp & 0x7UL))
                                stack_unaligned(sp);

                        if (unlikely(copy_to_user((char __user *)sp,
                                                  rwin, winsize)))
                                goto barf;
                } while (window--);
        }
        set_thread_wsaved(0);
        return;

barf:
        set_thread_wsaved(window + 1);
        do_exit(SIGILL);
}

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

#ifdef CONFIG_COMPAT
        if (test_thread_flag(TIF_32BIT)) {
                parent_tid_ptr = compat_ptr(regs->u_regs[UREG_I2]);
                child_tid_ptr = compat_ptr(regs->u_regs[UREG_I4]);
        } else
#endif
        {
                parent_tid_ptr = (int __user *) regs->u_regs[UREG_I2];
                child_tid_ptr = (int __user *) regs->u_regs[UREG_I4];
        }

        ret = do_fork(clone_flags, stack_start,
                      regs, stack_size,
                      parent_tid_ptr, 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
 */
int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
                unsigned long unused,
                struct task_struct *p, struct pt_regs *regs)
{
        struct thread_info *t = task_thread_info(p);
        struct sparc_stackf *parent_sf;
        unsigned long child_stack_sz;
        char *child_trap_frame;
        int kernel_thread;

        kernel_thread = (regs->tstate & TSTATE_PRIV) ? 1 : 0;
        parent_sf = ((struct sparc_stackf *) regs) - 1;

        /* Calculate offset to stack_frame & pt_regs */
        child_stack_sz = ((STACKFRAME_SZ + TRACEREG_SZ) +
                          (kernel_thread ? STACKFRAME_SZ : 0));
        child_trap_frame = (task_stack_page(p) +
                            (THREAD_SIZE - child_stack_sz));
        memcpy(child_trap_frame, parent_sf, child_stack_sz);

        t->flags = (t->flags & ~((0xffUL << TI_FLAG_CWP_SHIFT) |
                                 (0xffUL << TI_FLAG_CURRENT_DS_SHIFT))) |
                (((regs->tstate + 1) & TSTATE_CWP) << TI_FLAG_CWP_SHIFT);
        t->new_child = 1;
        t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
        t->kregs = (struct pt_regs *) (child_trap_frame +
                                       sizeof(struct sparc_stackf));
        t->fpsaved[0] = 0;

        if (kernel_thread) {
                struct sparc_stackf *child_sf = (struct sparc_stackf *)
                        (child_trap_frame + (STACKFRAME_SZ + TRACEREG_SZ));

                /* Zero terminate the stack backtrace.  */
                child_sf->fp = NULL;
                t->kregs->u_regs[UREG_FP] =
                  ((unsigned long) child_sf) - STACK_BIAS;

                /* Special case, if we are spawning a kernel thread from
                 * a userspace task (usermode helper, NFS or similar), we
                 * must disable performance counters in the child because
                 * the address space and protection realm are changing.
                 */
                if (t->flags & _TIF_PERFCTR) {
                        t->user_cntd0 = t->user_cntd1 = NULL;
                        t->pcr_reg = 0;
                        t->flags &= ~_TIF_PERFCTR;
                }
                t->flags |= ((long)ASI_P << TI_FLAG_CURRENT_DS_SHIFT);
                t->kregs->u_regs[UREG_G6] = (unsigned long) t;
                t->kregs->u_regs[UREG_G4] = (unsigned long) t->task;
        } else {
                if (t->flags & _TIF_32BIT) {
                        sp &= 0x00000000ffffffffUL;
                        regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
                }
                t->kregs->u_regs[UREG_FP] = sp;
                t->flags |= ((long)ASI_AIUS << TI_FLAG_CURRENT_DS_SHIFT);
                if (sp != regs->u_regs[UREG_FP]) {
                        unsigned long csp;

                        csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
                        if (!csp)
                                return -EFAULT;
                        t->kregs->u_regs[UREG_FP] = csp;
                }
                if (t->utraps)
                        t->utraps[0]++;
        }

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

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

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

        return 0;
}

/*
 * 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;

        /* If the parent runs before fn(arg) is called by the child,
         * the input registers of this function can be clobbered.
         * So we stash 'fn' and 'arg' into global registers which
         * will not be modified by the parent.
         */
        __asm__ __volatile__("mov %4, %%g2\n\t"    /* Save FN into global */
                             "mov %5, %%g3\n\t"    /* Save ARG into global */
                             "mov %1, %%g1\n\t"    /* Clone syscall nr. */
                             "mov %2, %%o0\n\t"    /* Clone flags. */
                             "mov 0, %%o1\n\t"     /* usp arg == 0 */
                             "t 0x6d\n\t"          /* Linux/Sparc clone(). */
                             "brz,a,pn %%o1, 1f\n\t" /* Parent, just return. */
                             " mov %%o0, %0\n\t"
                             "jmpl %%g2, %%o7\n\t"   /* Call the function. */
                             " mov %%g3, %%o0\n\t"   /* Set arg in delay. */
                             "mov %3, %%g1\n\t"
                             "t 0x6d\n\t"          /* Linux/Sparc exit(). */
                             /* Notreached by child. */
                             "1:" :
                             "=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;
}

typedef struct {
        union {
                unsigned int    pr_regs[32];
                unsigned long   pr_dregs[16];
        } pr_fr;
        unsigned int __unused;
        unsigned int    pr_fsr;
        unsigned char   pr_qcnt;
        unsigned char   pr_q_entrysize;
        unsigned char   pr_en;
        unsigned int    pr_q[64];
} elf_fpregset_t32;

/*
 * fill in the fpu structure for a core dump.
 */
int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
{
        unsigned long *kfpregs = current_thread_info()->fpregs;
        unsigned long fprs = current_thread_info()->fpsaved[0];

        if (test_thread_flag(TIF_32BIT)) {
                elf_fpregset_t32 *fpregs32 = (elf_fpregset_t32 *)fpregs;

                if (fprs & FPRS_DL)
                        memcpy(&fpregs32->pr_fr.pr_regs[0], kfpregs,
                               sizeof(unsigned int) * 32);
                else
                        memset(&fpregs32->pr_fr.pr_regs[0], 0,
                               sizeof(unsigned int) * 32);
                fpregs32->pr_qcnt = 0;
                fpregs32->pr_q_entrysize = 8;
                memset(&fpregs32->pr_q[0], 0,
                       (sizeof(unsigned int) * 64));
                if (fprs & FPRS_FEF) {
                        fpregs32->pr_fsr = (unsigned int) current_thread_info()->xfsr[0];
                        fpregs32->pr_en = 1;
                } else {
                        fpregs32->pr_fsr = 0;
                        fpregs32->pr_en = 0;
                }
        } else {
                if(fprs & FPRS_DL)
                        memcpy(&fpregs->pr_regs[0], kfpregs,
                               sizeof(unsigned int) * 32);
                else
                        memset(&fpregs->pr_regs[0], 0,
                               sizeof(unsigned int) * 32);
                if(fprs & FPRS_DU)
                        memcpy(&fpregs->pr_regs[16], kfpregs+16,
                               sizeof(unsigned int) * 32);
                else
                        memset(&fpregs->pr_regs[16], 0,
                               sizeof(unsigned int) * 32);
                if(fprs & FPRS_FEF) {
                        fpregs->pr_fsr = current_thread_info()->xfsr[0];
                        fpregs->pr_gsr = current_thread_info()->gsr[0];
                } else {
                        fpregs->pr_fsr = fpregs->pr_gsr = 0;
                }
                fpregs->pr_fprs = fprs;
        }
        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;
        char *filename;

        /* User register window flush is done by entry.S */

        /* 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,
                          (char __user * __user *)
                          regs->u_regs[base + UREG_I1],
                          (char __user * __user *)
                          regs->u_regs[base + UREG_I2], regs);
        putname(filename);
        if (!error) {
                fprs_write(0);
                current_thread_info()->xfsr[0] = 0;
                current_thread_info()->fpsaved[0] = 0;
                regs->tstate &= ~TSTATE_PEF;
        }
out:
        return error;
}

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

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

        tp = task_thread_info(task);
        bias = STACK_BIAS;
        fp = task_thread_info(task)->ksp + bias;

        do {
                if (!kstack_valid(tp, fp))
                        break;
                rw = (struct reg_window *) 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;
}