[IA64] Synchronize kernel RSE to user-space and back

[deliverable/linux.git] / arch / ia64 / kernel / process.c

/*
 * Architecture-specific setup.
 *
 * Copyright (C) 1998-2003 Hewlett-Packard Co
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 * 04/11/17 Ashok Raj   <ashok.raj@intel.com> Added CPU Hotplug Support
 *
 * 2005-10-07 Keith Owens <kaos@sgi.com>
 *            Add notify_die() hooks.
 */
#include <linux/cpu.h>
#include <linux/pm.h>
#include <linux/elf.h>
#include <linux/errno.h>
#include <linux/kallsyms.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/personality.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/thread_info.h>
#include <linux/unistd.h>
#include <linux/efi.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/kdebug.h>
#include <linux/utsname.h>

#include <asm/cpu.h>
#include <asm/delay.h>
#include <asm/elf.h>
#include <asm/ia32.h>
#include <asm/irq.h>
#include <asm/kexec.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/sal.h>
#include <asm/tlbflush.h>
#include <asm/uaccess.h>
#include <asm/unwind.h>
#include <asm/user.h>

#include "entry.h"

#ifdef CONFIG_PERFMON
# include <asm/perfmon.h>
#endif

#include "sigframe.h"

void (*ia64_mark_idle)(int);
static DEFINE_PER_CPU(unsigned int, cpu_idle_state);

unsigned long boot_option_idle_override = 0;
EXPORT_SYMBOL(boot_option_idle_override);

void
ia64_do_show_stack (struct unw_frame_info *info, void *arg)
{
        unsigned long ip, sp, bsp;
        char buf[128];                  /* don't make it so big that it overflows the stack! */

        printk("\nCall Trace:\n");
        do {
                unw_get_ip(info, &ip);
                if (ip == 0)
                        break;

                unw_get_sp(info, &sp);
                unw_get_bsp(info, &bsp);
                snprintf(buf, sizeof(buf),
                         " [<%016lx>] %%s\n"
                         "                                sp=%016lx bsp=%016lx\n",
                         ip, sp, bsp);
                print_symbol(buf, ip);
        } while (unw_unwind(info) >= 0);
}

void
show_stack (struct task_struct *task, unsigned long *sp)
{
        if (!task)
                unw_init_running(ia64_do_show_stack, NULL);
        else {
                struct unw_frame_info info;

                unw_init_from_blocked_task(&info, task);
                ia64_do_show_stack(&info, NULL);
        }
}

void
dump_stack (void)
{
        show_stack(NULL, NULL);
}

EXPORT_SYMBOL(dump_stack);

void
show_regs (struct pt_regs *regs)
{
        unsigned long ip = regs->cr_iip + ia64_psr(regs)->ri;

        print_modules();
        printk("\nPid: %d, CPU %d, comm: %20s\n", task_pid_nr(current),
                        smp_processor_id(), current->comm);
        printk("psr : %016lx ifs : %016lx ip  : [<%016lx>]    %s (%s)\n",
               regs->cr_ipsr, regs->cr_ifs, ip, print_tainted(),
               init_utsname()->release);
        print_symbol("ip is at %s\n", ip);
        printk("unat: %016lx pfs : %016lx rsc : %016lx\n",
               regs->ar_unat, regs->ar_pfs, regs->ar_rsc);
        printk("rnat: %016lx bsps: %016lx pr  : %016lx\n",
               regs->ar_rnat, regs->ar_bspstore, regs->pr);
        printk("ldrs: %016lx ccv : %016lx fpsr: %016lx\n",
               regs->loadrs, regs->ar_ccv, regs->ar_fpsr);
        printk("csd : %016lx ssd : %016lx\n", regs->ar_csd, regs->ar_ssd);
        printk("b0  : %016lx b6  : %016lx b7  : %016lx\n", regs->b0, regs->b6, regs->b7);
        printk("f6  : %05lx%016lx f7  : %05lx%016lx\n",
               regs->f6.u.bits[1], regs->f6.u.bits[0],
               regs->f7.u.bits[1], regs->f7.u.bits[0]);
        printk("f8  : %05lx%016lx f9  : %05lx%016lx\n",
               regs->f8.u.bits[1], regs->f8.u.bits[0],
               regs->f9.u.bits[1], regs->f9.u.bits[0]);
        printk("f10 : %05lx%016lx f11 : %05lx%016lx\n",
               regs->f10.u.bits[1], regs->f10.u.bits[0],
               regs->f11.u.bits[1], regs->f11.u.bits[0]);

        printk("r1  : %016lx r2  : %016lx r3  : %016lx\n", regs->r1, regs->r2, regs->r3);
        printk("r8  : %016lx r9  : %016lx r10 : %016lx\n", regs->r8, regs->r9, regs->r10);
        printk("r11 : %016lx r12 : %016lx r13 : %016lx\n", regs->r11, regs->r12, regs->r13);
        printk("r14 : %016lx r15 : %016lx r16 : %016lx\n", regs->r14, regs->r15, regs->r16);
        printk("r17 : %016lx r18 : %016lx r19 : %016lx\n", regs->r17, regs->r18, regs->r19);
        printk("r20 : %016lx r21 : %016lx r22 : %016lx\n", regs->r20, regs->r21, regs->r22);
        printk("r23 : %016lx r24 : %016lx r25 : %016lx\n", regs->r23, regs->r24, regs->r25);
        printk("r26 : %016lx r27 : %016lx r28 : %016lx\n", regs->r26, regs->r27, regs->r28);
        printk("r29 : %016lx r30 : %016lx r31 : %016lx\n", regs->r29, regs->r30, regs->r31);

        if (user_mode(regs)) {
                /* print the stacked registers */
                unsigned long val, *bsp, ndirty;
                int i, sof, is_nat = 0;

                sof = regs->cr_ifs & 0x7f;      /* size of frame */
                ndirty = (regs->loadrs >> 19);
                bsp = ia64_rse_skip_regs((unsigned long *) regs->ar_bspstore, ndirty);
                for (i = 0; i < sof; ++i) {
                        get_user(val, (unsigned long __user *) ia64_rse_skip_regs(bsp, i));
                        printk("r%-3u:%c%016lx%s", 32 + i, is_nat ? '*' : ' ', val,
                               ((i == sof - 1) || (i % 3) == 2) ? "\n" : " ");
                }
        } else
                show_stack(NULL, NULL);
}

void tsk_clear_notify_resume(struct task_struct *tsk)
{
#ifdef CONFIG_PERFMON
        if (tsk->thread.pfm_needs_checking)
                return;
#endif
        if (test_ti_thread_flag(task_thread_info(tsk), TIF_RESTORE_RSE))
                return;
        clear_ti_thread_flag(task_thread_info(tsk), TIF_NOTIFY_RESUME);
}

void
do_notify_resume_user (sigset_t *unused, struct sigscratch *scr, long in_syscall)
{
        if (fsys_mode(current, &scr->pt)) {
                /* defer signal-handling etc. until we return to privilege-level 0.  */
                if (!ia64_psr(&scr->pt)->lp)
                        ia64_psr(&scr->pt)->lp = 1;
                return;
        }

#ifdef CONFIG_PERFMON
        if (current->thread.pfm_needs_checking)
                pfm_handle_work();
#endif

        /* deal with pending signal delivery */
        if (test_thread_flag(TIF_SIGPENDING)||test_thread_flag(TIF_RESTORE_SIGMASK))
                ia64_do_signal(scr, in_syscall);

        /* copy user rbs to kernel rbs */
        if (unlikely(test_thread_flag(TIF_RESTORE_RSE)))
                ia64_sync_krbs();
}

static int pal_halt        = 1;
static int can_do_pal_halt = 1;

static int __init nohalt_setup(char * str)
{
        pal_halt = can_do_pal_halt = 0;
        return 1;
}
__setup("nohalt", nohalt_setup);

void
update_pal_halt_status(int status)
{
        can_do_pal_halt = pal_halt && status;
}

/*
 * We use this if we don't have any better idle routine..
 */
void
default_idle (void)
{
        local_irq_enable();
        while (!need_resched()) {
                if (can_do_pal_halt) {
                        local_irq_disable();
                        if (!need_resched()) {
                                safe_halt();
                        }
                        local_irq_enable();
                } else
                        cpu_relax();
        }
}

#ifdef CONFIG_HOTPLUG_CPU
/* We don't actually take CPU down, just spin without interrupts. */
static inline void play_dead(void)
{
        extern void ia64_cpu_local_tick (void);
        unsigned int this_cpu = smp_processor_id();

        /* Ack it */
        __get_cpu_var(cpu_state) = CPU_DEAD;

        max_xtp();
        local_irq_disable();
        idle_task_exit();
        ia64_jump_to_sal(&sal_boot_rendez_state[this_cpu]);
        /*
         * The above is a point of no-return, the processor is
         * expected to be in SAL loop now.
         */
        BUG();
}
#else
static inline void play_dead(void)
{
        BUG();
}
#endif /* CONFIG_HOTPLUG_CPU */

void cpu_idle_wait(void)
{
        unsigned int cpu, this_cpu = get_cpu();
        cpumask_t map;
        cpumask_t tmp = current->cpus_allowed;

        set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
        put_cpu();

        cpus_clear(map);
        for_each_online_cpu(cpu) {
                per_cpu(cpu_idle_state, cpu) = 1;
                cpu_set(cpu, map);
        }

        __get_cpu_var(cpu_idle_state) = 0;

        wmb();
        do {
                ssleep(1);
                for_each_online_cpu(cpu) {
                        if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
                                cpu_clear(cpu, map);
                }
                cpus_and(map, map, cpu_online_map);
        } while (!cpus_empty(map));
        set_cpus_allowed(current, tmp);
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);

void __attribute__((noreturn))
cpu_idle (void)
{
        void (*mark_idle)(int) = ia64_mark_idle;
        int cpu = smp_processor_id();

        /* endless idle loop with no priority at all */
        while (1) {
                if (can_do_pal_halt) {
                        current_thread_info()->status &= ~TS_POLLING;
                        /*
                         * TS_POLLING-cleared state must be visible before we
                         * test NEED_RESCHED:
                         */
                        smp_mb();
                } else {
                        current_thread_info()->status |= TS_POLLING;
                }

                if (!need_resched()) {
                        void (*idle)(void);
#ifdef CONFIG_SMP
                        min_xtp();
#endif
                        if (__get_cpu_var(cpu_idle_state))
                                __get_cpu_var(cpu_idle_state) = 0;

                        rmb();
                        if (mark_idle)
                                (*mark_idle)(1);

                        idle = pm_idle;
                        if (!idle)
                                idle = default_idle;
                        (*idle)();
                        if (mark_idle)
                                (*mark_idle)(0);
#ifdef CONFIG_SMP
                        normal_xtp();
#endif
                }
                preempt_enable_no_resched();
                schedule();
                preempt_disable();
                check_pgt_cache();
                if (cpu_is_offline(cpu))
                        play_dead();
        }
}

void
ia64_save_extra (struct task_struct *task)
{
#ifdef CONFIG_PERFMON
        unsigned long info;
#endif

        if ((task->thread.flags & IA64_THREAD_DBG_VALID) != 0)
                ia64_save_debug_regs(&task->thread.dbr[0]);

#ifdef CONFIG_PERFMON
        if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
                pfm_save_regs(task);

        info = __get_cpu_var(pfm_syst_info);
        if (info & PFM_CPUINFO_SYST_WIDE)
                pfm_syst_wide_update_task(task, info, 0);
#endif

#ifdef CONFIG_IA32_SUPPORT
        if (IS_IA32_PROCESS(task_pt_regs(task)))
                ia32_save_state(task);
#endif
}

void
ia64_load_extra (struct task_struct *task)
{
#ifdef CONFIG_PERFMON
        unsigned long info;
#endif

        if ((task->thread.flags & IA64_THREAD_DBG_VALID) != 0)
                ia64_load_debug_regs(&task->thread.dbr[0]);

#ifdef CONFIG_PERFMON
        if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
                pfm_load_regs(task);

        info = __get_cpu_var(pfm_syst_info);
        if (info & PFM_CPUINFO_SYST_WIDE) 
                pfm_syst_wide_update_task(task, info, 1);
#endif

#ifdef CONFIG_IA32_SUPPORT
        if (IS_IA32_PROCESS(task_pt_regs(task)))
                ia32_load_state(task);
#endif
}

/*
 * Copy the state of an ia-64 thread.
 *
 * We get here through the following  call chain:
 *
 *      from user-level:        from kernel:
 *
 *      <clone syscall>         <some kernel call frames>
 *      sys_clone                  :
 *      do_fork                 do_fork
 *      copy_thread             copy_thread
 *
 * This means that the stack layout is as follows:
 *
 *      +---------------------+ (highest addr)
 *      |   struct pt_regs    |
 *      +---------------------+
 *      | struct switch_stack |
 *      +---------------------+
 *      |                     |
 *      |    memory stack     |
 *      |                     | <-- sp (lowest addr)
 *      +---------------------+
 *
 * Observe that we copy the unat values that are in pt_regs and switch_stack.  Spilling an
 * integer to address X causes bit N in ar.unat to be set to the NaT bit of the register,
 * with N=(X & 0x1ff)/8.  Thus, copying the unat value preserves the NaT bits ONLY if the
 * pt_regs structure in the parent is congruent to that of the child, modulo 512.  Since
 * the stack is page aligned and the page size is at least 4KB, this is always the case,
 * so there is nothing to worry about.
 */
int
copy_thread (int nr, unsigned long clone_flags,
             unsigned long user_stack_base, unsigned long user_stack_size,
             struct task_struct *p, struct pt_regs *regs)
{
        extern char ia64_ret_from_clone, ia32_ret_from_clone;
        struct switch_stack *child_stack, *stack;
        unsigned long rbs, child_rbs, rbs_size;
        struct pt_regs *child_ptregs;
        int retval = 0;

#ifdef CONFIG_SMP
        /*
         * For SMP idle threads, fork_by_hand() calls do_fork with
         * NULL regs.
         */
        if (!regs)
                return 0;
#endif

        stack = ((struct switch_stack *) regs) - 1;

        child_ptregs = (struct pt_regs *) ((unsigned long) p + IA64_STK_OFFSET) - 1;
        child_stack = (struct switch_stack *) child_ptregs - 1;

        /* copy parent's switch_stack & pt_regs to child: */
        memcpy(child_stack, stack, sizeof(*child_ptregs) + sizeof(*child_stack));

        rbs = (unsigned long) current + IA64_RBS_OFFSET;
        child_rbs = (unsigned long) p + IA64_RBS_OFFSET;
        rbs_size = stack->ar_bspstore - rbs;

        /* copy the parent's register backing store to the child: */
        memcpy((void *) child_rbs, (void *) rbs, rbs_size);

        if (likely(user_mode(child_ptregs))) {
                if ((clone_flags & CLONE_SETTLS) && !IS_IA32_PROCESS(regs))
                        child_ptregs->r13 = regs->r16;  /* see sys_clone2() in entry.S */
                if (user_stack_base) {
                        child_ptregs->r12 = user_stack_base + user_stack_size - 16;
                        child_ptregs->ar_bspstore = user_stack_base;
                        child_ptregs->ar_rnat = 0;
                        child_ptregs->loadrs = 0;
                }
        } else {
                /*
                 * Note: we simply preserve the relative position of
                 * the stack pointer here.  There is no need to
                 * allocate a scratch area here, since that will have
                 * been taken care of by the caller of sys_clone()
                 * already.
                 */
                child_ptregs->r12 = (unsigned long) child_ptregs - 16; /* kernel sp */
                child_ptregs->r13 = (unsigned long) p;          /* set `current' pointer */
        }
        child_stack->ar_bspstore = child_rbs + rbs_size;
        if (IS_IA32_PROCESS(regs))
                child_stack->b0 = (unsigned long) &ia32_ret_from_clone;
        else
                child_stack->b0 = (unsigned long) &ia64_ret_from_clone;

        /* copy parts of thread_struct: */
        p->thread.ksp = (unsigned long) child_stack - 16;

        /* stop some PSR bits from being inherited.
         * the psr.up/psr.pp bits must be cleared on fork but inherited on execve()
         * therefore we must specify them explicitly here and not include them in
         * IA64_PSR_BITS_TO_CLEAR.
         */
        child_ptregs->cr_ipsr = ((child_ptregs->cr_ipsr | IA64_PSR_BITS_TO_SET)
                                 & ~(IA64_PSR_BITS_TO_CLEAR | IA64_PSR_PP | IA64_PSR_UP));

        /*
         * NOTE: The calling convention considers all floating point
         * registers in the high partition (fph) to be scratch.  Since
         * the only way to get to this point is through a system call,
         * we know that the values in fph are all dead.  Hence, there
         * is no need to inherit the fph state from the parent to the
         * child and all we have to do is to make sure that
         * IA64_THREAD_FPH_VALID is cleared in the child.
         *
         * XXX We could push this optimization a bit further by
         * clearing IA64_THREAD_FPH_VALID on ANY system call.
         * However, it's not clear this is worth doing.  Also, it
         * would be a slight deviation from the normal Linux system
         * call behavior where scratch registers are preserved across
         * system calls (unless used by the system call itself).
         */
#       define THREAD_FLAGS_TO_CLEAR    (IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID \
                                         | IA64_THREAD_PM_VALID)
#       define THREAD_FLAGS_TO_SET      0
        p->thread.flags = ((current->thread.flags & ~THREAD_FLAGS_TO_CLEAR)
                           | THREAD_FLAGS_TO_SET);
        ia64_drop_fpu(p);       /* don't pick up stale state from a CPU's fph */
#ifdef CONFIG_IA32_SUPPORT
        /*
         * If we're cloning an IA32 task then save the IA32 extra
         * state from the current task to the new task
         */
        if (IS_IA32_PROCESS(task_pt_regs(current))) {
                ia32_save_state(p);
                if (clone_flags & CLONE_SETTLS)
                        retval = ia32_clone_tls(p, child_ptregs);

                /* Copy partially mapped page list */
                if (!retval)
                        retval = ia32_copy_ia64_partial_page_list(p,
                                                                clone_flags);
        }
#endif

#ifdef CONFIG_PERFMON
        if (current->thread.pfm_context)
                pfm_inherit(p, child_ptregs);
#endif
        return retval;
}

static void
do_copy_task_regs (struct task_struct *task, struct unw_frame_info *info, void *arg)
{
        unsigned long mask, sp, nat_bits = 0, ar_rnat, urbs_end, cfm;
        unsigned long uninitialized_var(ip);    /* GCC be quiet */
        elf_greg_t *dst = arg;
        struct pt_regs *pt;
        char nat;
        int i;

        memset(dst, 0, sizeof(elf_gregset_t));  /* don't leak any kernel bits to user-level */

        if (unw_unwind_to_user(info) < 0)
                return;

        unw_get_sp(info, &sp);
        pt = (struct pt_regs *) (sp + 16);

        urbs_end = ia64_get_user_rbs_end(task, pt, &cfm);

        if (ia64_sync_user_rbs(task, info->sw, pt->ar_bspstore, urbs_end) < 0)
                return;

        ia64_peek(task, info->sw, urbs_end, (long) ia64_rse_rnat_addr((long *) urbs_end),
                  &ar_rnat);

        /*
         * coredump format:
         *      r0-r31
         *      NaT bits (for r0-r31; bit N == 1 iff rN is a NaT)
         *      predicate registers (p0-p63)
         *      b0-b7
         *      ip cfm user-mask
         *      ar.rsc ar.bsp ar.bspstore ar.rnat
         *      ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec
         */

        /* r0 is zero */
        for (i = 1, mask = (1UL << i); i < 32; ++i) {
                unw_get_gr(info, i, &dst[i], &nat);
                if (nat)
                        nat_bits |= mask;
                mask <<= 1;
        }
        dst[32] = nat_bits;
        unw_get_pr(info, &dst[33]);

        for (i = 0; i < 8; ++i)
                unw_get_br(info, i, &dst[34 + i]);

        unw_get_rp(info, &ip);
        dst[42] = ip + ia64_psr(pt)->ri;
        dst[43] = cfm;
        dst[44] = pt->cr_ipsr & IA64_PSR_UM;

        unw_get_ar(info, UNW_AR_RSC, &dst[45]);
        /*
         * For bsp and bspstore, unw_get_ar() would return the kernel
         * addresses, but we need the user-level addresses instead:
         */
        dst[46] = urbs_end;     /* note: by convention PT_AR_BSP points to the end of the urbs! */
        dst[47] = pt->ar_bspstore;
        dst[48] = ar_rnat;
        unw_get_ar(info, UNW_AR_CCV, &dst[49]);
        unw_get_ar(info, UNW_AR_UNAT, &dst[50]);
        unw_get_ar(info, UNW_AR_FPSR, &dst[51]);
        dst[52] = pt->ar_pfs;   /* UNW_AR_PFS is == to pt->cr_ifs for interrupt frames */
        unw_get_ar(info, UNW_AR_LC, &dst[53]);
        unw_get_ar(info, UNW_AR_EC, &dst[54]);
        unw_get_ar(info, UNW_AR_CSD, &dst[55]);
        unw_get_ar(info, UNW_AR_SSD, &dst[56]);
}

void
do_dump_task_fpu (struct task_struct *task, struct unw_frame_info *info, void *arg)
{
        elf_fpreg_t *dst = arg;
        int i;

        memset(dst, 0, sizeof(elf_fpregset_t)); /* don't leak any "random" bits */

        if (unw_unwind_to_user(info) < 0)
                return;

        /* f0 is 0.0, f1 is 1.0 */

        for (i = 2; i < 32; ++i)
                unw_get_fr(info, i, dst + i);

        ia64_flush_fph(task);
        if ((task->thread.flags & IA64_THREAD_FPH_VALID) != 0)
                memcpy(dst + 32, task->thread.fph, 96*16);
}

void
do_copy_regs (struct unw_frame_info *info, void *arg)
{
        do_copy_task_regs(current, info, arg);
}

void
do_dump_fpu (struct unw_frame_info *info, void *arg)
{
        do_dump_task_fpu(current, info, arg);
}

int
dump_task_regs(struct task_struct *task, elf_gregset_t *regs)
{
        struct unw_frame_info tcore_info;

        if (current == task) {
                unw_init_running(do_copy_regs, regs);
        } else {
                memset(&tcore_info, 0, sizeof(tcore_info));
                unw_init_from_blocked_task(&tcore_info, task);
                do_copy_task_regs(task, &tcore_info, regs);
        }
        return 1;
}

void
ia64_elf_core_copy_regs (struct pt_regs *pt, elf_gregset_t dst)
{
        unw_init_running(do_copy_regs, dst);
}

int
dump_task_fpu (struct task_struct *task, elf_fpregset_t *dst)
{
        struct unw_frame_info tcore_info;

        if (current == task) {
                unw_init_running(do_dump_fpu, dst);
        } else {
                memset(&tcore_info, 0, sizeof(tcore_info));
                unw_init_from_blocked_task(&tcore_info, task);
                do_dump_task_fpu(task, &tcore_info, dst);
        }
        return 1;
}

int
dump_fpu (struct pt_regs *pt, elf_fpregset_t dst)
{
        unw_init_running(do_dump_fpu, dst);
        return 1;       /* f0-f31 are always valid so we always return 1 */
}

long
sys_execve (char __user *filename, char __user * __user *argv, char __user * __user *envp,
            struct pt_regs *regs)
{
        char *fname;
        int error;

        fname = getname(filename);
        error = PTR_ERR(fname);
        if (IS_ERR(fname))
                goto out;
        error = do_execve(fname, argv, envp, regs);
        putname(fname);
out:
        return error;
}

pid_t
kernel_thread (int (*fn)(void *), void *arg, unsigned long flags)
{
        extern void start_kernel_thread (void);
        unsigned long *helper_fptr = (unsigned long *) &start_kernel_thread;
        struct {
                struct switch_stack sw;
                struct pt_regs pt;
        } regs;

        memset(&regs, 0, sizeof(regs));
        regs.pt.cr_iip = helper_fptr[0];        /* set entry point (IP) */
        regs.pt.r1 = helper_fptr[1];            /* set GP */
        regs.pt.r9 = (unsigned long) fn;        /* 1st argument */
        regs.pt.r11 = (unsigned long) arg;      /* 2nd argument */
        /* Preserve PSR bits, except for bits 32-34 and 37-45, which we can't read.  */
        regs.pt.cr_ipsr = ia64_getreg(_IA64_REG_PSR) | IA64_PSR_BN;
        regs.pt.cr_ifs = 1UL << 63;             /* mark as valid, empty frame */
        regs.sw.ar_fpsr = regs.pt.ar_fpsr = ia64_getreg(_IA64_REG_AR_FPSR);
        regs.sw.ar_bspstore = (unsigned long) current + IA64_RBS_OFFSET;
        regs.sw.pr = (1 << PRED_KERNEL_STACK);
        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs.pt, 0, NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);

/* This gets called from kernel_thread() via ia64_invoke_thread_helper().  */
int
kernel_thread_helper (int (*fn)(void *), void *arg)
{
#ifdef CONFIG_IA32_SUPPORT
        if (IS_IA32_PROCESS(task_pt_regs(current))) {
                /* A kernel thread is always a 64-bit process. */
                current->thread.map_base  = DEFAULT_MAP_BASE;
                current->thread.task_size = DEFAULT_TASK_SIZE;
                ia64_set_kr(IA64_KR_IO_BASE, current->thread.old_iob);
                ia64_set_kr(IA64_KR_TSSD, current->thread.old_k1);
        }
#endif
        return (*fn)(arg);
}

/*
 * Flush thread state.  This is called when a thread does an execve().
 */
void
flush_thread (void)
{
        /* drop floating-point and debug-register state if it exists: */
        current->thread.flags &= ~(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID);
        ia64_drop_fpu(current);
#ifdef CONFIG_IA32_SUPPORT
        if (IS_IA32_PROCESS(task_pt_regs(current))) {
                ia32_drop_ia64_partial_page_list(current);
                current->thread.task_size = IA32_PAGE_OFFSET;
                set_fs(USER_DS);
                memset(current->thread.tls_array, 0, sizeof(current->thread.tls_array));
        }
#endif
}

/*
 * Clean up state associated with current thread.  This is called when
 * the thread calls exit().
 */
void
exit_thread (void)
{

        ia64_drop_fpu(current);
#ifdef CONFIG_PERFMON
       /* if needed, stop monitoring and flush state to perfmon context */
        if (current->thread.pfm_context)
                pfm_exit_thread(current);

        /* free debug register resources */
        if (current->thread.flags & IA64_THREAD_DBG_VALID)
                pfm_release_debug_registers(current);
#endif
        if (IS_IA32_PROCESS(task_pt_regs(current)))
                ia32_drop_ia64_partial_page_list(current);
}

unsigned long
get_wchan (struct task_struct *p)
{
        struct unw_frame_info info;
        unsigned long ip;
        int count = 0;

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

        /*
         * Note: p may not be a blocked task (it could be current or
         * another process running on some other CPU.  Rather than
         * trying to determine if p is really blocked, we just assume
         * it's blocked and rely on the unwind routines to fail
         * gracefully if the process wasn't really blocked after all.
         * --davidm 99/12/15
         */
        unw_init_from_blocked_task(&info, p);
        do {
                if (p->state == TASK_RUNNING)
                        return 0;
                if (unw_unwind(&info) < 0)
                        return 0;
                unw_get_ip(&info, &ip);
                if (!in_sched_functions(ip))
                        return ip;
        } while (count++ < 16);
        return 0;
}

void
cpu_halt (void)
{
        pal_power_mgmt_info_u_t power_info[8];
        unsigned long min_power;
        int i, min_power_state;

        if (ia64_pal_halt_info(power_info) != 0)
                return;

        min_power_state = 0;
        min_power = power_info[0].pal_power_mgmt_info_s.power_consumption;
        for (i = 1; i < 8; ++i)
                if (power_info[i].pal_power_mgmt_info_s.im
                    && power_info[i].pal_power_mgmt_info_s.power_consumption < min_power) {
                        min_power = power_info[i].pal_power_mgmt_info_s.power_consumption;
                        min_power_state = i;
                }

        while (1)
                ia64_pal_halt(min_power_state);
}

void machine_shutdown(void)
{
#ifdef CONFIG_HOTPLUG_CPU
        int cpu;

        for_each_online_cpu(cpu) {
                if (cpu != smp_processor_id())
                        cpu_down(cpu);
        }
#endif
#ifdef CONFIG_KEXEC
        kexec_disable_iosapic();
#endif
}

void
machine_restart (char *restart_cmd)
{
        (void) notify_die(DIE_MACHINE_RESTART, restart_cmd, NULL, 0, 0, 0);
        (*efi.reset_system)(EFI_RESET_WARM, 0, 0, NULL);
}

void
machine_halt (void)
{
        (void) notify_die(DIE_MACHINE_HALT, "", NULL, 0, 0, 0);
        cpu_halt();
}

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