Merge tag 'drm-vc4-fixes-2015-01-19' of http://github.com/anholt/linux into drm-fixes

[mirror_ubuntu-zesty-kernel.git] / arch / powerpc / kernel / process.c

/*
 *  Derived from "arch/i386/kernel/process.c"
 *    Copyright (C) 1995  Linus Torvalds
 *
 *  Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
 *  Paul Mackerras (paulus@cs.anu.edu.au)
 *
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
#include <linux/export.h>
#include <linux/kallsyms.h>
#include <linux/mqueue.h>
#include <linux/hardirq.h>
#include <linux/utsname.h>
#include <linux/ftrace.h>
#include <linux/kernel_stat.h>
#include <linux/personality.h>
#include <linux/random.h>
#include <linux/hw_breakpoint.h>
#include <linux/uaccess.h>

#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/time.h>
#include <asm/runlatch.h>
#include <asm/syscalls.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
#include <asm/debug.h>
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#endif
#include <asm/code-patching.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>

/* Transactional Memory debug */
#ifdef TM_DEBUG_SW
#define TM_DEBUG(x...) printk(KERN_INFO x)
#else
#define TM_DEBUG(x...) do { } while(0)
#endif

extern unsigned long _get_SP(void);

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static void check_if_tm_restore_required(struct task_struct *tsk)
{
        /*
         * If we are saving the current thread's registers, and the
         * thread is in a transactional state, set the TIF_RESTORE_TM
         * bit so that we know to restore the registers before
         * returning to userspace.
         */
        if (tsk == current && tsk->thread.regs &&
            MSR_TM_ACTIVE(tsk->thread.regs->msr) &&
            !test_thread_flag(TIF_RESTORE_TM)) {
                tsk->thread.ckpt_regs.msr = tsk->thread.regs->msr;
                set_thread_flag(TIF_RESTORE_TM);
        }
}
#else
static inline void check_if_tm_restore_required(struct task_struct *tsk) { }
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */

bool strict_msr_control;
EXPORT_SYMBOL(strict_msr_control);

static int __init enable_strict_msr_control(char *str)
{
        strict_msr_control = true;
        pr_info("Enabling strict facility control\n");

        return 0;
}
early_param("ppc_strict_facility_enable", enable_strict_msr_control);

void msr_check_and_set(unsigned long bits)
{
        unsigned long oldmsr = mfmsr();
        unsigned long newmsr;

        newmsr = oldmsr | bits;

#ifdef CONFIG_VSX
        if (cpu_has_feature(CPU_FTR_VSX) && (bits & MSR_FP))
                newmsr |= MSR_VSX;
#endif

        if (oldmsr != newmsr)
                mtmsr_isync(newmsr);
}

void __msr_check_and_clear(unsigned long bits)
{
        unsigned long oldmsr = mfmsr();
        unsigned long newmsr;

        newmsr = oldmsr & ~bits;

#ifdef CONFIG_VSX
        if (cpu_has_feature(CPU_FTR_VSX) && (bits & MSR_FP))
                newmsr &= ~MSR_VSX;
#endif

        if (oldmsr != newmsr)
                mtmsr_isync(newmsr);
}
EXPORT_SYMBOL(__msr_check_and_clear);

#ifdef CONFIG_PPC_FPU
void giveup_fpu(struct task_struct *tsk)
{
        check_if_tm_restore_required(tsk);

        msr_check_and_set(MSR_FP);
        __giveup_fpu(tsk);
        msr_check_and_clear(MSR_FP);
}
EXPORT_SYMBOL(giveup_fpu);

/*
 * Make sure the floating-point register state in the
 * the thread_struct is up to date for task tsk.
 */
void flush_fp_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                /*
                 * We need to disable preemption here because if we didn't,
                 * another process could get scheduled after the regs->msr
                 * test but before we have finished saving the FP registers
                 * to the thread_struct.  That process could take over the
                 * FPU, and then when we get scheduled again we would store
                 * bogus values for the remaining FP registers.
                 */
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_FP) {
                        /*
                         * This should only ever be called for current or
                         * for a stopped child process.  Since we save away
                         * the FP register state on context switch,
                         * there is something wrong if a stopped child appears
                         * to still have its FP state in the CPU registers.
                         */
                        BUG_ON(tsk != current);
                        giveup_fpu(tsk);
                }
                preempt_enable();
        }
}
EXPORT_SYMBOL_GPL(flush_fp_to_thread);

void enable_kernel_fp(void)
{
        WARN_ON(preemptible());

        msr_check_and_set(MSR_FP);

        if (current->thread.regs && (current->thread.regs->msr & MSR_FP)) {
                check_if_tm_restore_required(current);
                __giveup_fpu(current);
        }
}
EXPORT_SYMBOL(enable_kernel_fp);
#endif /* CONFIG_PPC_FPU */

#ifdef CONFIG_ALTIVEC
void giveup_altivec(struct task_struct *tsk)
{
        check_if_tm_restore_required(tsk);

        msr_check_and_set(MSR_VEC);
        __giveup_altivec(tsk);
        msr_check_and_clear(MSR_VEC);
}
EXPORT_SYMBOL(giveup_altivec);

void enable_kernel_altivec(void)
{
        WARN_ON(preemptible());

        msr_check_and_set(MSR_VEC);

        if (current->thread.regs && (current->thread.regs->msr & MSR_VEC)) {
                check_if_tm_restore_required(current);
                __giveup_altivec(current);
        }
}
EXPORT_SYMBOL(enable_kernel_altivec);

/*
 * Make sure the VMX/Altivec register state in the
 * the thread_struct is up to date for task tsk.
 */
void flush_altivec_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_VEC) {
                        BUG_ON(tsk != current);
                        giveup_altivec(tsk);
                }
                preempt_enable();
        }
}
EXPORT_SYMBOL_GPL(flush_altivec_to_thread);
#endif /* CONFIG_ALTIVEC */

#ifdef CONFIG_VSX
void giveup_vsx(struct task_struct *tsk)
{
        check_if_tm_restore_required(tsk);

        msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
        if (tsk->thread.regs->msr & MSR_FP)
                __giveup_fpu(tsk);
        if (tsk->thread.regs->msr & MSR_VEC)
                __giveup_altivec(tsk);
        __giveup_vsx(tsk);
        msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
}
EXPORT_SYMBOL(giveup_vsx);

void enable_kernel_vsx(void)
{
        WARN_ON(preemptible());

        msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);

        if (current->thread.regs && (current->thread.regs->msr & MSR_VSX)) {
                check_if_tm_restore_required(current);
                if (current->thread.regs->msr & MSR_FP)
                        __giveup_fpu(current);
                if (current->thread.regs->msr & MSR_VEC)
                        __giveup_altivec(current);
                __giveup_vsx(current);
        }
}
EXPORT_SYMBOL(enable_kernel_vsx);

void flush_vsx_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_VSX) {
                        BUG_ON(tsk != current);
                        giveup_vsx(tsk);
                }
                preempt_enable();
        }
}
EXPORT_SYMBOL_GPL(flush_vsx_to_thread);
#endif /* CONFIG_VSX */

#ifdef CONFIG_SPE
void giveup_spe(struct task_struct *tsk)
{
        check_if_tm_restore_required(tsk);

        msr_check_and_set(MSR_SPE);
        __giveup_spe(tsk);
        msr_check_and_clear(MSR_SPE);
}
EXPORT_SYMBOL(giveup_spe);

void enable_kernel_spe(void)
{
        WARN_ON(preemptible());

        msr_check_and_set(MSR_SPE);

        if (current->thread.regs && (current->thread.regs->msr & MSR_SPE)) {
                check_if_tm_restore_required(current);
                __giveup_spe(current);
        }
}
EXPORT_SYMBOL(enable_kernel_spe);

void flush_spe_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_SPE) {
                        BUG_ON(tsk != current);
                        tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
                        giveup_spe(tsk);
                }
                preempt_enable();
        }
}
#endif /* CONFIG_SPE */

static unsigned long msr_all_available;

static int __init init_msr_all_available(void)
{
#ifdef CONFIG_PPC_FPU
        msr_all_available |= MSR_FP;
#endif
#ifdef CONFIG_ALTIVEC
        if (cpu_has_feature(CPU_FTR_ALTIVEC))
                msr_all_available |= MSR_VEC;
#endif
#ifdef CONFIG_VSX
        if (cpu_has_feature(CPU_FTR_VSX))
                msr_all_available |= MSR_VSX;
#endif
#ifdef CONFIG_SPE
        if (cpu_has_feature(CPU_FTR_SPE))
                msr_all_available |= MSR_SPE;
#endif

        return 0;
}
early_initcall(init_msr_all_available);

void giveup_all(struct task_struct *tsk)
{
        unsigned long usermsr;

        if (!tsk->thread.regs)
                return;

        usermsr = tsk->thread.regs->msr;

        if ((usermsr & msr_all_available) == 0)
                return;

        msr_check_and_set(msr_all_available);

#ifdef CONFIG_PPC_FPU
        if (usermsr & MSR_FP)
                __giveup_fpu(tsk);
#endif
#ifdef CONFIG_ALTIVEC
        if (usermsr & MSR_VEC)
                __giveup_altivec(tsk);
#endif
#ifdef CONFIG_VSX
        if (usermsr & MSR_VSX)
                __giveup_vsx(tsk);
#endif
#ifdef CONFIG_SPE
        if (usermsr & MSR_SPE)
                __giveup_spe(tsk);
#endif

        msr_check_and_clear(msr_all_available);
}
EXPORT_SYMBOL(giveup_all);

void flush_all_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                BUG_ON(tsk != current);
                giveup_all(tsk);

#ifdef CONFIG_SPE
                if (tsk->thread.regs->msr & MSR_SPE)
                        tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
#endif

                preempt_enable();
        }
}
EXPORT_SYMBOL(flush_all_to_thread);

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
void do_send_trap(struct pt_regs *regs, unsigned long address,
                  unsigned long error_code, int signal_code, int breakpt)
{
        siginfo_t info;

        current->thread.trap_nr = signal_code;
        if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
                        11, SIGSEGV) == NOTIFY_STOP)
                return;

        /* Deliver the signal to userspace */
        info.si_signo = SIGTRAP;
        info.si_errno = breakpt;        /* breakpoint or watchpoint id */
        info.si_code = signal_code;
        info.si_addr = (void __user *)address;
        force_sig_info(SIGTRAP, &info, current);
}
#else   /* !CONFIG_PPC_ADV_DEBUG_REGS */
void do_break (struct pt_regs *regs, unsigned long address,
                    unsigned long error_code)
{
        siginfo_t info;

        current->thread.trap_nr = TRAP_HWBKPT;
        if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
                        11, SIGSEGV) == NOTIFY_STOP)
                return;

        if (debugger_break_match(regs))
                return;

        /* Clear the breakpoint */
        hw_breakpoint_disable();

        /* Deliver the signal to userspace */
        info.si_signo = SIGTRAP;
        info.si_errno = 0;
        info.si_code = TRAP_HWBKPT;
        info.si_addr = (void __user *)address;
        force_sig_info(SIGTRAP, &info, current);
}
#endif  /* CONFIG_PPC_ADV_DEBUG_REGS */

static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk);

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
/*
 * Set the debug registers back to their default "safe" values.
 */
static void set_debug_reg_defaults(struct thread_struct *thread)
{
        thread->debug.iac1 = thread->debug.iac2 = 0;
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
        thread->debug.iac3 = thread->debug.iac4 = 0;
#endif
        thread->debug.dac1 = thread->debug.dac2 = 0;
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
        thread->debug.dvc1 = thread->debug.dvc2 = 0;
#endif
        thread->debug.dbcr0 = 0;
#ifdef CONFIG_BOOKE
        /*
         * Force User/Supervisor bits to b11 (user-only MSR[PR]=1)
         */
        thread->debug.dbcr1 = DBCR1_IAC1US | DBCR1_IAC2US |
                        DBCR1_IAC3US | DBCR1_IAC4US;
        /*
         * Force Data Address Compare User/Supervisor bits to be User-only
         * (0b11 MSR[PR]=1) and set all other bits in DBCR2 register to be 0.
         */
        thread->debug.dbcr2 = DBCR2_DAC1US | DBCR2_DAC2US;
#else
        thread->debug.dbcr1 = 0;
#endif
}

static void prime_debug_regs(struct debug_reg *debug)
{
        /*
         * We could have inherited MSR_DE from userspace, since
         * it doesn't get cleared on exception entry.  Make sure
         * MSR_DE is clear before we enable any debug events.
         */
        mtmsr(mfmsr() & ~MSR_DE);

        mtspr(SPRN_IAC1, debug->iac1);
        mtspr(SPRN_IAC2, debug->iac2);
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
        mtspr(SPRN_IAC3, debug->iac3);
        mtspr(SPRN_IAC4, debug->iac4);
#endif
        mtspr(SPRN_DAC1, debug->dac1);
        mtspr(SPRN_DAC2, debug->dac2);
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
        mtspr(SPRN_DVC1, debug->dvc1);
        mtspr(SPRN_DVC2, debug->dvc2);
#endif
        mtspr(SPRN_DBCR0, debug->dbcr0);
        mtspr(SPRN_DBCR1, debug->dbcr1);
#ifdef CONFIG_BOOKE
        mtspr(SPRN_DBCR2, debug->dbcr2);
#endif
}
/*
 * Unless neither the old or new thread are making use of the
 * debug registers, set the debug registers from the values
 * stored in the new thread.
 */
void switch_booke_debug_regs(struct debug_reg *new_debug)
{
        if ((current->thread.debug.dbcr0 & DBCR0_IDM)
                || (new_debug->dbcr0 & DBCR0_IDM))
                        prime_debug_regs(new_debug);
}
EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
#else   /* !CONFIG_PPC_ADV_DEBUG_REGS */
#ifndef CONFIG_HAVE_HW_BREAKPOINT
static void set_debug_reg_defaults(struct thread_struct *thread)
{
        thread->hw_brk.address = 0;
        thread->hw_brk.type = 0;
        set_breakpoint(&thread->hw_brk);
}
#endif /* !CONFIG_HAVE_HW_BREAKPOINT */
#endif  /* CONFIG_PPC_ADV_DEBUG_REGS */

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
{
        mtspr(SPRN_DAC1, dabr);
#ifdef CONFIG_PPC_47x
        isync();
#endif
        return 0;
}
#elif defined(CONFIG_PPC_BOOK3S)
static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
{
        mtspr(SPRN_DABR, dabr);
        if (cpu_has_feature(CPU_FTR_DABRX))
                mtspr(SPRN_DABRX, dabrx);
        return 0;
}
#else
static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
{
        return -EINVAL;
}
#endif

static inline int set_dabr(struct arch_hw_breakpoint *brk)
{
        unsigned long dabr, dabrx;

        dabr = brk->address | (brk->type & HW_BRK_TYPE_DABR);
        dabrx = ((brk->type >> 3) & 0x7);

        if (ppc_md.set_dabr)
                return ppc_md.set_dabr(dabr, dabrx);

        return __set_dabr(dabr, dabrx);
}

static inline int set_dawr(struct arch_hw_breakpoint *brk)
{
        unsigned long dawr, dawrx, mrd;

        dawr = brk->address;

        dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) \
                                   << (63 - 58); //* read/write bits */
        dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) \
                                   << (63 - 59); //* translate */
        dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) \
                                   >> 3; //* PRIM bits */
        /* dawr length is stored in field MDR bits 48:53.  Matches range in
           doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
           0b111111=64DW.
           brk->len is in bytes.
           This aligns up to double word size, shifts and does the bias.
        */
        mrd = ((brk->len + 7) >> 3) - 1;
        dawrx |= (mrd & 0x3f) << (63 - 53);

        if (ppc_md.set_dawr)
                return ppc_md.set_dawr(dawr, dawrx);
        mtspr(SPRN_DAWR, dawr);
        mtspr(SPRN_DAWRX, dawrx);
        return 0;
}

void __set_breakpoint(struct arch_hw_breakpoint *brk)
{
        memcpy(this_cpu_ptr(&current_brk), brk, sizeof(*brk));

        if (cpu_has_feature(CPU_FTR_DAWR))
                set_dawr(brk);
        else
                set_dabr(brk);
}

void set_breakpoint(struct arch_hw_breakpoint *brk)
{
        preempt_disable();
        __set_breakpoint(brk);
        preempt_enable();
}

#ifdef CONFIG_PPC64
DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
#endif

static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
                              struct arch_hw_breakpoint *b)
{
        if (a->address != b->address)
                return false;
        if (a->type != b->type)
                return false;
        if (a->len != b->len)
                return false;
        return true;
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static void tm_reclaim_thread(struct thread_struct *thr,
                              struct thread_info *ti, uint8_t cause)
{
        unsigned long msr_diff = 0;

        /*
         * If FP/VSX registers have been already saved to the
         * thread_struct, move them to the transact_fp array.
         * We clear the TIF_RESTORE_TM bit since after the reclaim
         * the thread will no longer be transactional.
         */
        if (test_ti_thread_flag(ti, TIF_RESTORE_TM)) {
                msr_diff = thr->ckpt_regs.msr & ~thr->regs->msr;
                if (msr_diff & MSR_FP)
                        memcpy(&thr->transact_fp, &thr->fp_state,
                               sizeof(struct thread_fp_state));
                if (msr_diff & MSR_VEC)
                        memcpy(&thr->transact_vr, &thr->vr_state,
                               sizeof(struct thread_vr_state));
                clear_ti_thread_flag(ti, TIF_RESTORE_TM);
                msr_diff &= MSR_FP | MSR_VEC | MSR_VSX | MSR_FE0 | MSR_FE1;
        }

        /*
         * Use the current MSR TM suspended bit to track if we have
         * checkpointed state outstanding.
         * On signal delivery, we'd normally reclaim the checkpointed
         * state to obtain stack pointer (see:get_tm_stackpointer()).
         * This will then directly return to userspace without going
         * through __switch_to(). However, if the stack frame is bad,
         * we need to exit this thread which calls __switch_to() which
         * will again attempt to reclaim the already saved tm state.
         * Hence we need to check that we've not already reclaimed
         * this state.
         * We do this using the current MSR, rather tracking it in
         * some specific thread_struct bit, as it has the additional
         * benifit of checking for a potential TM bad thing exception.
         */
        if (!MSR_TM_SUSPENDED(mfmsr()))
                return;

        tm_reclaim(thr, thr->regs->msr, cause);

        /* Having done the reclaim, we now have the checkpointed
         * FP/VSX values in the registers.  These might be valid
         * even if we have previously called enable_kernel_fp() or
         * flush_fp_to_thread(), so update thr->regs->msr to
         * indicate their current validity.
         */
        thr->regs->msr |= msr_diff;
}

void tm_reclaim_current(uint8_t cause)
{
        tm_enable();
        tm_reclaim_thread(&current->thread, current_thread_info(), cause);
}

static inline void tm_reclaim_task(struct task_struct *tsk)
{
        /* We have to work out if we're switching from/to a task that's in the
         * middle of a transaction.
         *
         * In switching we need to maintain a 2nd register state as
         * oldtask->thread.ckpt_regs.  We tm_reclaim(oldproc); this saves the
         * checkpointed (tbegin) state in ckpt_regs and saves the transactional
         * (current) FPRs into oldtask->thread.transact_fpr[].
         *
         * We also context switch (save) TFHAR/TEXASR/TFIAR in here.
         */
        struct thread_struct *thr = &tsk->thread;

        if (!thr->regs)
                return;

        if (!MSR_TM_ACTIVE(thr->regs->msr))
                goto out_and_saveregs;

        /* Stash the original thread MSR, as giveup_fpu et al will
         * modify it.  We hold onto it to see whether the task used
         * FP & vector regs.  If the TIF_RESTORE_TM flag is set,
         * ckpt_regs.msr is already set.
         */
        if (!test_ti_thread_flag(task_thread_info(tsk), TIF_RESTORE_TM))
                thr->ckpt_regs.msr = thr->regs->msr;

        TM_DEBUG("--- tm_reclaim on pid %d (NIP=%lx, "
                 "ccr=%lx, msr=%lx, trap=%lx)\n",
                 tsk->pid, thr->regs->nip,
                 thr->regs->ccr, thr->regs->msr,
                 thr->regs->trap);

        tm_reclaim_thread(thr, task_thread_info(tsk), TM_CAUSE_RESCHED);

        TM_DEBUG("--- tm_reclaim on pid %d complete\n",
                 tsk->pid);

out_and_saveregs:
        /* Always save the regs here, even if a transaction's not active.
         * This context-switches a thread's TM info SPRs.  We do it here to
         * be consistent with the restore path (in recheckpoint) which
         * cannot happen later in _switch().
         */
        tm_save_sprs(thr);
}

extern void __tm_recheckpoint(struct thread_struct *thread,
                              unsigned long orig_msr);

void tm_recheckpoint(struct thread_struct *thread,
                     unsigned long orig_msr)
{
        unsigned long flags;

        /* We really can't be interrupted here as the TEXASR registers can't
         * change and later in the trecheckpoint code, we have a userspace R1.
         * So let's hard disable over this region.
         */
        local_irq_save(flags);
        hard_irq_disable();

        /* The TM SPRs are restored here, so that TEXASR.FS can be set
         * before the trecheckpoint and no explosion occurs.
         */
        tm_restore_sprs(thread);

        __tm_recheckpoint(thread, orig_msr);

        local_irq_restore(flags);
}

static inline void tm_recheckpoint_new_task(struct task_struct *new)
{
        unsigned long msr;

        if (!cpu_has_feature(CPU_FTR_TM))
                return;

        /* Recheckpoint the registers of the thread we're about to switch to.
         *
         * If the task was using FP, we non-lazily reload both the original and
         * the speculative FP register states.  This is because the kernel
         * doesn't see if/when a TM rollback occurs, so if we take an FP
         * unavoidable later, we are unable to determine which set of FP regs
         * need to be restored.
         */
        if (!new->thread.regs)
                return;

        if (!MSR_TM_ACTIVE(new->thread.regs->msr)){
                tm_restore_sprs(&new->thread);
                return;
        }
        msr = new->thread.ckpt_regs.msr;
        /* Recheckpoint to restore original checkpointed register state. */
        TM_DEBUG("*** tm_recheckpoint of pid %d "
                 "(new->msr 0x%lx, new->origmsr 0x%lx)\n",
                 new->pid, new->thread.regs->msr, msr);

        /* This loads the checkpointed FP/VEC state, if used */
        tm_recheckpoint(&new->thread, msr);

        /* This loads the speculative FP/VEC state, if used */
        if (msr & MSR_FP) {
                do_load_up_transact_fpu(&new->thread);
                new->thread.regs->msr |=
                        (MSR_FP | new->thread.fpexc_mode);
        }
#ifdef CONFIG_ALTIVEC
        if (msr & MSR_VEC) {
                do_load_up_transact_altivec(&new->thread);
                new->thread.regs->msr |= MSR_VEC;
        }
#endif
        /* We may as well turn on VSX too since all the state is restored now */
        if (msr & MSR_VSX)
                new->thread.regs->msr |= MSR_VSX;

        TM_DEBUG("*** tm_recheckpoint of pid %d complete "
                 "(kernel msr 0x%lx)\n",
                 new->pid, mfmsr());
}

static inline void __switch_to_tm(struct task_struct *prev)
{
        if (cpu_has_feature(CPU_FTR_TM)) {
                tm_enable();
                tm_reclaim_task(prev);
        }
}

/*
 * This is called if we are on the way out to userspace and the
 * TIF_RESTORE_TM flag is set.  It checks if we need to reload
 * FP and/or vector state and does so if necessary.
 * If userspace is inside a transaction (whether active or
 * suspended) and FP/VMX/VSX instructions have ever been enabled
 * inside that transaction, then we have to keep them enabled
 * and keep the FP/VMX/VSX state loaded while ever the transaction
 * continues.  The reason is that if we didn't, and subsequently
 * got a FP/VMX/VSX unavailable interrupt inside a transaction,
 * we don't know whether it's the same transaction, and thus we
 * don't know which of the checkpointed state and the transactional
 * state to use.
 */
void restore_tm_state(struct pt_regs *regs)
{
        unsigned long msr_diff;

        clear_thread_flag(TIF_RESTORE_TM);
        if (!MSR_TM_ACTIVE(regs->msr))
                return;

        msr_diff = current->thread.ckpt_regs.msr & ~regs->msr;
        msr_diff &= MSR_FP | MSR_VEC | MSR_VSX;
        if (msr_diff & MSR_FP) {
                msr_check_and_set(MSR_FP);
                load_fp_state(&current->thread.fp_state);
                msr_check_and_clear(MSR_FP);
                regs->msr |= current->thread.fpexc_mode;
        }
        if (msr_diff & MSR_VEC) {
                msr_check_and_set(MSR_VEC);
                load_vr_state(&current->thread.vr_state);
                msr_check_and_clear(MSR_VEC);
        }
        regs->msr |= msr_diff;
}

#else
#define tm_recheckpoint_new_task(new)
#define __switch_to_tm(prev)
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */

static inline void save_sprs(struct thread_struct *t)
{
#ifdef CONFIG_ALTIVEC
        if (cpu_has_feature(cpu_has_feature(CPU_FTR_ALTIVEC)))
                t->vrsave = mfspr(SPRN_VRSAVE);
#endif
#ifdef CONFIG_PPC_BOOK3S_64
        if (cpu_has_feature(CPU_FTR_DSCR))
                t->dscr = mfspr(SPRN_DSCR);

        if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
                t->bescr = mfspr(SPRN_BESCR);
                t->ebbhr = mfspr(SPRN_EBBHR);
                t->ebbrr = mfspr(SPRN_EBBRR);

                t->fscr = mfspr(SPRN_FSCR);

                /*
                 * Note that the TAR is not available for use in the kernel.
                 * (To provide this, the TAR should be backed up/restored on
                 * exception entry/exit instead, and be in pt_regs.  FIXME,
                 * this should be in pt_regs anyway (for debug).)
                 */
                t->tar = mfspr(SPRN_TAR);
        }
#endif
}

static inline void restore_sprs(struct thread_struct *old_thread,
                                struct thread_struct *new_thread)
{
#ifdef CONFIG_ALTIVEC
        if (cpu_has_feature(CPU_FTR_ALTIVEC) &&
            old_thread->vrsave != new_thread->vrsave)
                mtspr(SPRN_VRSAVE, new_thread->vrsave);
#endif
#ifdef CONFIG_PPC_BOOK3S_64
        if (cpu_has_feature(CPU_FTR_DSCR)) {
                u64 dscr = get_paca()->dscr_default;
                u64 fscr = old_thread->fscr & ~FSCR_DSCR;

                if (new_thread->dscr_inherit) {
                        dscr = new_thread->dscr;
                        fscr |= FSCR_DSCR;
                }

                if (old_thread->dscr != dscr)
                        mtspr(SPRN_DSCR, dscr);

                if (old_thread->fscr != fscr)
                        mtspr(SPRN_FSCR, fscr);
        }

        if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
                if (old_thread->bescr != new_thread->bescr)
                        mtspr(SPRN_BESCR, new_thread->bescr);
                if (old_thread->ebbhr != new_thread->ebbhr)
                        mtspr(SPRN_EBBHR, new_thread->ebbhr);
                if (old_thread->ebbrr != new_thread->ebbrr)
                        mtspr(SPRN_EBBRR, new_thread->ebbrr);

                if (old_thread->tar != new_thread->tar)
                        mtspr(SPRN_TAR, new_thread->tar);
        }
#endif
}

struct task_struct *__switch_to(struct task_struct *prev,
        struct task_struct *new)
{
        struct thread_struct *new_thread, *old_thread;
        struct task_struct *last;
#ifdef CONFIG_PPC_BOOK3S_64
        struct ppc64_tlb_batch *batch;
#endif

        new_thread = &new->thread;
        old_thread = &current->thread;

        WARN_ON(!irqs_disabled());

#ifdef CONFIG_PPC64
        /*
         * Collect processor utilization data per process
         */
        if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
                struct cpu_usage *cu = this_cpu_ptr(&cpu_usage_array);
                long unsigned start_tb, current_tb;
                start_tb = old_thread->start_tb;
                cu->current_tb = current_tb = mfspr(SPRN_PURR);
                old_thread->accum_tb += (current_tb - start_tb);
                new_thread->start_tb = current_tb;
        }
#endif /* CONFIG_PPC64 */

#ifdef CONFIG_PPC_BOOK3S_64
        batch = this_cpu_ptr(&ppc64_tlb_batch);
        if (batch->active) {
                current_thread_info()->local_flags |= _TLF_LAZY_MMU;
                if (batch->index)
                        __flush_tlb_pending(batch);
                batch->active = 0;
        }
#endif /* CONFIG_PPC_BOOK3S_64 */

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
        switch_booke_debug_regs(&new->thread.debug);
#else
/*
 * For PPC_BOOK3S_64, we use the hw-breakpoint interfaces that would
 * schedule DABR
 */
#ifndef CONFIG_HAVE_HW_BREAKPOINT
        if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk), &new->thread.hw_brk)))
                __set_breakpoint(&new->thread.hw_brk);
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
#endif

        /*
         * We need to save SPRs before treclaim/trecheckpoint as these will
         * change a number of them.
         */
        save_sprs(&prev->thread);

        __switch_to_tm(prev);

        /* Save FPU, Altivec, VSX and SPE state */
        giveup_all(prev);

        /*
         * We can't take a PMU exception inside _switch() since there is a
         * window where the kernel stack SLB and the kernel stack are out
         * of sync. Hard disable here.
         */
        hard_irq_disable();

        tm_recheckpoint_new_task(new);

        /*
         * Call restore_sprs() before calling _switch(). If we move it after
         * _switch() then we miss out on calling it for new tasks. The reason
         * for this is we manually create a stack frame for new tasks that
         * directly returns through ret_from_fork() or
         * ret_from_kernel_thread(). See copy_thread() for details.
         */
        restore_sprs(old_thread, new_thread);

        last = _switch(old_thread, new_thread);

#ifdef CONFIG_PPC_BOOK3S_64
        if (current_thread_info()->local_flags & _TLF_LAZY_MMU) {
                current_thread_info()->local_flags &= ~_TLF_LAZY_MMU;
                batch = this_cpu_ptr(&ppc64_tlb_batch);
                batch->active = 1;
        }
#endif /* CONFIG_PPC_BOOK3S_64 */

        return last;
}

static int instructions_to_print = 16;

static void show_instructions(struct pt_regs *regs)
{
        int i;
        unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
                        sizeof(int));

        printk("Instruction dump:");

        for (i = 0; i < instructions_to_print; i++) {
                int instr;

                if (!(i % 8))
                        printk("\n");

#if !defined(CONFIG_BOOKE)
                /* If executing with the IMMU off, adjust pc rather
                 * than print XXXXXXXX.
                 */
                if (!(regs->msr & MSR_IR))
                        pc = (unsigned long)phys_to_virt(pc);
#endif

                if (!__kernel_text_address(pc) ||
                     probe_kernel_address((unsigned int __user *)pc, instr)) {
                        printk(KERN_CONT "XXXXXXXX ");
                } else {
                        if (regs->nip == pc)
                                printk(KERN_CONT "<%08x> ", instr);
                        else
                                printk(KERN_CONT "%08x ", instr);
                }

                pc += sizeof(int);
        }

        printk("\n");
}

struct regbit {
        unsigned long bit;
        const char *name;
};

static struct regbit msr_bits[] = {
#if defined(CONFIG_PPC64) && !defined(CONFIG_BOOKE)
        {MSR_SF,        "SF"},
        {MSR_HV,        "HV"},
#endif
        {MSR_VEC,       "VEC"},
        {MSR_VSX,       "VSX"},
#ifdef CONFIG_BOOKE
        {MSR_CE,        "CE"},
#endif
        {MSR_EE,        "EE"},
        {MSR_PR,        "PR"},
        {MSR_FP,        "FP"},
        {MSR_ME,        "ME"},
#ifdef CONFIG_BOOKE
        {MSR_DE,        "DE"},
#else
        {MSR_SE,        "SE"},
        {MSR_BE,        "BE"},
#endif
        {MSR_IR,        "IR"},
        {MSR_DR,        "DR"},
        {MSR_PMM,       "PMM"},
#ifndef CONFIG_BOOKE
        {MSR_RI,        "RI"},
        {MSR_LE,        "LE"},
#endif
        {0,             NULL}
};

static void print_bits(unsigned long val, struct regbit *bits, const char *sep)
{
        const char *s = "";

        for (; bits->bit; ++bits)
                if (val & bits->bit) {
                        printk("%s%s", s, bits->name);
                        s = sep;
                }
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static struct regbit msr_tm_bits[] = {
        {MSR_TS_T,      "T"},
        {MSR_TS_S,      "S"},
        {MSR_TM,        "E"},
        {0,             NULL}
};

static void print_tm_bits(unsigned long val)
{
/*
 * This only prints something if at least one of the TM bit is set.
 * Inside the TM[], the output means:
 *   E: Enabled         (bit 32)
 *   S: Suspended       (bit 33)
 *   T: Transactional   (bit 34)
 */
        if (val & (MSR_TM | MSR_TS_S | MSR_TS_T)) {
                printk(",TM[");
                print_bits(val, msr_tm_bits, "");
                printk("]");
        }
}
#else
static void print_tm_bits(unsigned long val) {}
#endif

static void print_msr_bits(unsigned long val)
{
        printk("<");
        print_bits(val, msr_bits, ",");
        print_tm_bits(val);
        printk(">");
}

#ifdef CONFIG_PPC64
#define REG             "%016lx"
#define REGS_PER_LINE   4
#define LAST_VOLATILE   13
#else
#define REG             "%08lx"
#define REGS_PER_LINE   8
#define LAST_VOLATILE   12
#endif

void show_regs(struct pt_regs * regs)
{
        int i, trap;

        show_regs_print_info(KERN_DEFAULT);

        printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
               regs->nip, regs->link, regs->ctr);
        printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
               regs, regs->trap, print_tainted(), init_utsname()->release);
        printk("MSR: "REG" ", regs->msr);
        print_msr_bits(regs->msr);
        printk("  CR: %08lx  XER: %08lx\n", regs->ccr, regs->xer);
        trap = TRAP(regs);
        if ((regs->trap != 0xc00) && cpu_has_feature(CPU_FTR_CFAR))
                printk("CFAR: "REG" ", regs->orig_gpr3);
        if (trap == 0x200 || trap == 0x300 || trap == 0x600)
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
                printk("DEAR: "REG" ESR: "REG" ", regs->dar, regs->dsisr);
#else
                printk("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
#endif
#ifdef CONFIG_PPC64
        printk("SOFTE: %ld ", regs->softe);
#endif
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        if (MSR_TM_ACTIVE(regs->msr))
                printk("\nPACATMSCRATCH: %016llx ", get_paca()->tm_scratch);
#endif

        for (i = 0;  i < 32;  i++) {
                if ((i % REGS_PER_LINE) == 0)
                        printk("\nGPR%02d: ", i);
                printk(REG " ", regs->gpr[i]);
                if (i == LAST_VOLATILE && !FULL_REGS(regs))
                        break;
        }
        printk("\n");
#ifdef CONFIG_KALLSYMS
        /*
         * Lookup NIP late so we have the best change of getting the
         * above info out without failing
         */
        printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
        printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
#endif
        show_stack(current, (unsigned long *) regs->gpr[1]);
        if (!user_mode(regs))
                show_instructions(regs);
}

void exit_thread(void)
{
}

void flush_thread(void)
{
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        flush_ptrace_hw_breakpoint(current);
#else /* CONFIG_HAVE_HW_BREAKPOINT */
        set_debug_reg_defaults(&current->thread);
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
}

void
release_thread(struct task_struct *t)
{
}

/*
 * this gets called so that we can store coprocessor state into memory and
 * copy the current task into the new thread.
 */
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
        flush_all_to_thread(src);
        /*
         * Flush TM state out so we can copy it.  __switch_to_tm() does this
         * flush but it removes the checkpointed state from the current CPU and
         * transitions the CPU out of TM mode.  Hence we need to call
         * tm_recheckpoint_new_task() (on the same task) to restore the
         * checkpointed state back and the TM mode.
         */
        __switch_to_tm(src);
        tm_recheckpoint_new_task(src);

        *dst = *src;

        clear_task_ebb(dst);

        return 0;
}

static void setup_ksp_vsid(struct task_struct *p, unsigned long sp)
{
#ifdef CONFIG_PPC_STD_MMU_64
        unsigned long sp_vsid;
        unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;

        if (mmu_has_feature(MMU_FTR_1T_SEGMENT))
                sp_vsid = get_kernel_vsid(sp, MMU_SEGSIZE_1T)
                        << SLB_VSID_SHIFT_1T;
        else
                sp_vsid = get_kernel_vsid(sp, MMU_SEGSIZE_256M)
                        << SLB_VSID_SHIFT;
        sp_vsid |= SLB_VSID_KERNEL | llp;
        p->thread.ksp_vsid = sp_vsid;
#endif
}

/*
 * Copy a thread..
 */

/*
 * Copy architecture-specific thread state
 */
int copy_thread(unsigned long clone_flags, unsigned long usp,
                unsigned long kthread_arg, struct task_struct *p)
{
        struct pt_regs *childregs, *kregs;
        extern void ret_from_fork(void);
        extern void ret_from_kernel_thread(void);
        void (*f)(void);
        unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

        /* Copy registers */
        sp -= sizeof(struct pt_regs);
        childregs = (struct pt_regs *) sp;
        if (unlikely(p->flags & PF_KTHREAD)) {
                /* kernel thread */
                struct thread_info *ti = (void *)task_stack_page(p);
                memset(childregs, 0, sizeof(struct pt_regs));
                childregs->gpr[1] = sp + sizeof(struct pt_regs);
                /* function */
                if (usp)
                        childregs->gpr[14] = ppc_function_entry((void *)usp);
#ifdef CONFIG_PPC64
                clear_tsk_thread_flag(p, TIF_32BIT);
                childregs->softe = 1;
#endif
                childregs->gpr[15] = kthread_arg;
                p->thread.regs = NULL;  /* no user register state */
                ti->flags |= _TIF_RESTOREALL;
                f = ret_from_kernel_thread;
        } else {
                /* user thread */
                struct pt_regs *regs = current_pt_regs();
                CHECK_FULL_REGS(regs);
                *childregs = *regs;
                if (usp)
                        childregs->gpr[1] = usp;
                p->thread.regs = childregs;
                childregs->gpr[3] = 0;  /* Result from fork() */
                if (clone_flags & CLONE_SETTLS) {
#ifdef CONFIG_PPC64
                        if (!is_32bit_task())
                                childregs->gpr[13] = childregs->gpr[6];
                        else
#endif
                                childregs->gpr[2] = childregs->gpr[6];
                }

                f = ret_from_fork;
        }
        sp -= STACK_FRAME_OVERHEAD;

        /*
         * The way this works is that at some point in the future
         * some task will call _switch to switch to the new task.
         * That will pop off the stack frame created below and start
         * the new task running at ret_from_fork.  The new task will
         * do some house keeping and then return from the fork or clone
         * system call, using the stack frame created above.
         */
        ((unsigned long *)sp)[0] = 0;
        sp -= sizeof(struct pt_regs);
        kregs = (struct pt_regs *) sp;
        sp -= STACK_FRAME_OVERHEAD;
        p->thread.ksp = sp;
#ifdef CONFIG_PPC32
        p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
                                _ALIGN_UP(sizeof(struct thread_info), 16);
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        p->thread.ptrace_bps[0] = NULL;
#endif

        p->thread.fp_save_area = NULL;
#ifdef CONFIG_ALTIVEC
        p->thread.vr_save_area = NULL;
#endif

        setup_ksp_vsid(p, sp);

#ifdef CONFIG_PPC64 
        if (cpu_has_feature(CPU_FTR_DSCR)) {
                p->thread.dscr_inherit = current->thread.dscr_inherit;
                p->thread.dscr = mfspr(SPRN_DSCR);
        }
        if (cpu_has_feature(CPU_FTR_HAS_PPR))
                p->thread.ppr = INIT_PPR;
#endif
        kregs->nip = ppc_function_entry(f);
        return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
{
#ifdef CONFIG_PPC64
        unsigned long load_addr = regs->gpr[2]; /* saved by ELF_PLAT_INIT */
#endif

        /*
         * If we exec out of a kernel thread then thread.regs will not be
         * set.  Do it now.
         */
        if (!current->thread.regs) {
                struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
                current->thread.regs = regs - 1;
        }

        memset(regs->gpr, 0, sizeof(regs->gpr));
        regs->ctr = 0;
        regs->link = 0;
        regs->xer = 0;
        regs->ccr = 0;
        regs->gpr[1] = sp;

        /*
         * We have just cleared all the nonvolatile GPRs, so make
         * FULL_REGS(regs) return true.  This is necessary to allow
         * ptrace to examine the thread immediately after exec.
         */
        regs->trap &= ~1UL;

#ifdef CONFIG_PPC32
        regs->mq = 0;
        regs->nip = start;
        regs->msr = MSR_USER;
#else
        if (!is_32bit_task()) {
                unsigned long entry;

                if (is_elf2_task()) {
                        /* Look ma, no function descriptors! */
                        entry = start;

                        /*
                         * Ulrich says:
                         *   The latest iteration of the ABI requires that when
                         *   calling a function (at its global entry point),
                         *   the caller must ensure r12 holds the entry point
                         *   address (so that the function can quickly
                         *   establish addressability).
                         */
                        regs->gpr[12] = start;
                        /* Make sure that's restored on entry to userspace. */
                        set_thread_flag(TIF_RESTOREALL);
                } else {
                        unsigned long toc;

                        /* start is a relocated pointer to the function
                         * descriptor for the elf _start routine.  The first
                         * entry in the function descriptor is the entry
                         * address of _start and the second entry is the TOC
                         * value we need to use.
                         */
                        __get_user(entry, (unsigned long __user *)start);
                        __get_user(toc, (unsigned long __user *)start+1);

                        /* Check whether the e_entry function descriptor entries
                         * need to be relocated before we can use them.
                         */
                        if (load_addr != 0) {
                                entry += load_addr;
                                toc   += load_addr;
                        }
                        regs->gpr[2] = toc;
                }
                regs->nip = entry;
                regs->msr = MSR_USER64;
        } else {
                regs->nip = start;
                regs->gpr[2] = 0;
                regs->msr = MSR_USER32;
        }
#endif
#ifdef CONFIG_VSX
        current->thread.used_vsr = 0;
#endif
        memset(&current->thread.fp_state, 0, sizeof(current->thread.fp_state));
        current->thread.fp_save_area = NULL;
#ifdef CONFIG_ALTIVEC
        memset(&current->thread.vr_state, 0, sizeof(current->thread.vr_state));
        current->thread.vr_state.vscr.u[3] = 0x00010000; /* Java mode disabled */
        current->thread.vr_save_area = NULL;
        current->thread.vrsave = 0;
        current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
        memset(current->thread.evr, 0, sizeof(current->thread.evr));
        current->thread.acc = 0;
        current->thread.spefscr = 0;
        current->thread.used_spe = 0;
#endif /* CONFIG_SPE */
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        if (cpu_has_feature(CPU_FTR_TM))
                regs->msr |= MSR_TM;
        current->thread.tm_tfhar = 0;
        current->thread.tm_texasr = 0;
        current->thread.tm_tfiar = 0;
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
}
EXPORT_SYMBOL(start_thread);

#define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
                | PR_FP_EXC_RES | PR_FP_EXC_INV)

int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
{
        struct pt_regs *regs = tsk->thread.regs;

        /* This is a bit hairy.  If we are an SPE enabled  processor
         * (have embedded fp) we store the IEEE exception enable flags in
         * fpexc_mode.  fpexc_mode is also used for setting FP exception
         * mode (asyn, precise, disabled) for 'Classic' FP. */
        if (val & PR_FP_EXC_SW_ENABLE) {
#ifdef CONFIG_SPE
                if (cpu_has_feature(CPU_FTR_SPE)) {
                        /*
                         * When the sticky exception bits are set
                         * directly by userspace, it must call prctl
                         * with PR_GET_FPEXC (with PR_FP_EXC_SW_ENABLE
                         * in the existing prctl settings) or
                         * PR_SET_FPEXC (with PR_FP_EXC_SW_ENABLE in
                         * the bits being set).  <fenv.h> functions
                         * saving and restoring the whole
                         * floating-point environment need to do so
                         * anyway to restore the prctl settings from
                         * the saved environment.
                         */
                        tsk->thread.spefscr_last = mfspr(SPRN_SPEFSCR);
                        tsk->thread.fpexc_mode = val &
                                (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
                        return 0;
                } else {
                        return -EINVAL;
                }
#else
                return -EINVAL;
#endif
        }

        /* on a CONFIG_SPE this does not hurt us.  The bits that
         * __pack_fe01 use do not overlap with bits used for
         * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
         * on CONFIG_SPE implementations are reserved so writing to
         * them does not change anything */
        if (val > PR_FP_EXC_PRECISE)
                return -EINVAL;
        tsk->thread.fpexc_mode = __pack_fe01(val);
        if (regs != NULL && (regs->msr & MSR_FP) != 0)
                regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
                        | tsk->thread.fpexc_mode;
        return 0;
}

int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
{
        unsigned int val;

        if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
#ifdef CONFIG_SPE
                if (cpu_has_feature(CPU_FTR_SPE)) {
                        /*
                         * When the sticky exception bits are set
                         * directly by userspace, it must call prctl
                         * with PR_GET_FPEXC (with PR_FP_EXC_SW_ENABLE
                         * in the existing prctl settings) or
                         * PR_SET_FPEXC (with PR_FP_EXC_SW_ENABLE in
                         * the bits being set).  <fenv.h> functions
                         * saving and restoring the whole
                         * floating-point environment need to do so
                         * anyway to restore the prctl settings from
                         * the saved environment.
                         */
                        tsk->thread.spefscr_last = mfspr(SPRN_SPEFSCR);
                        val = tsk->thread.fpexc_mode;
                } else
                        return -EINVAL;
#else
                return -EINVAL;
#endif
        else
                val = __unpack_fe01(tsk->thread.fpexc_mode);
        return put_user(val, (unsigned int __user *) adr);
}

int set_endian(struct task_struct *tsk, unsigned int val)
{
        struct pt_regs *regs = tsk->thread.regs;

        if ((val == PR_ENDIAN_LITTLE && !cpu_has_feature(CPU_FTR_REAL_LE)) ||
            (val == PR_ENDIAN_PPC_LITTLE && !cpu_has_feature(CPU_FTR_PPC_LE)))
                return -EINVAL;

        if (regs == NULL)
                return -EINVAL;

        if (val == PR_ENDIAN_BIG)
                regs->msr &= ~MSR_LE;
        else if (val == PR_ENDIAN_LITTLE || val == PR_ENDIAN_PPC_LITTLE)
                regs->msr |= MSR_LE;
        else
                return -EINVAL;

        return 0;
}

int get_endian(struct task_struct *tsk, unsigned long adr)
{
        struct pt_regs *regs = tsk->thread.regs;
        unsigned int val;

        if (!cpu_has_feature(CPU_FTR_PPC_LE) &&
            !cpu_has_feature(CPU_FTR_REAL_LE))
                return -EINVAL;

        if (regs == NULL)
                return -EINVAL;

        if (regs->msr & MSR_LE) {
                if (cpu_has_feature(CPU_FTR_REAL_LE))
                        val = PR_ENDIAN_LITTLE;
                else
                        val = PR_ENDIAN_PPC_LITTLE;
        } else
                val = PR_ENDIAN_BIG;

        return put_user(val, (unsigned int __user *)adr);
}

int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
{
        tsk->thread.align_ctl = val;
        return 0;
}

int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
{
        return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr);
}

static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
                                  unsigned long nbytes)
{
        unsigned long stack_page;
        unsigned long cpu = task_cpu(p);

        /*
         * Avoid crashing if the stack has overflowed and corrupted
         * task_cpu(p), which is in the thread_info struct.
         */
        if (cpu < NR_CPUS && cpu_possible(cpu)) {
                stack_page = (unsigned long) hardirq_ctx[cpu];
                if (sp >= stack_page + sizeof(struct thread_struct)
                    && sp <= stack_page + THREAD_SIZE - nbytes)
                        return 1;

                stack_page = (unsigned long) softirq_ctx[cpu];
                if (sp >= stack_page + sizeof(struct thread_struct)
                    && sp <= stack_page + THREAD_SIZE - nbytes)
                        return 1;
        }
        return 0;
}

int validate_sp(unsigned long sp, struct task_struct *p,
                       unsigned long nbytes)
{
        unsigned long stack_page = (unsigned long)task_stack_page(p);

        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

        return valid_irq_stack(sp, p, nbytes);
}

EXPORT_SYMBOL(validate_sp);

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

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

        sp = p->thread.ksp;
        if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
                return 0;

        do {
                sp = *(unsigned long *)sp;
                if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
                        return 0;
                if (count > 0) {
                        ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE];
                        if (!in_sched_functions(ip))
                                return ip;
                }
        } while (count++ < 16);
        return 0;
}

static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;

void show_stack(struct task_struct *tsk, unsigned long *stack)
{
        unsigned long sp, ip, lr, newsp;
        int count = 0;
        int firstframe = 1;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        int curr_frame = current->curr_ret_stack;
        extern void return_to_handler(void);
        unsigned long rth = (unsigned long)return_to_handler;
#endif

        sp = (unsigned long) stack;
        if (tsk == NULL)
                tsk = current;
        if (sp == 0) {
                if (tsk == current)
                        sp = current_stack_pointer();
                else
                        sp = tsk->thread.ksp;
        }

        lr = 0;
        printk("Call Trace:\n");
        do {
                if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
                        return;

                stack = (unsigned long *) sp;
                newsp = stack[0];
                ip = stack[STACK_FRAME_LR_SAVE];
                if (!firstframe || ip != lr) {
                        printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
                        if ((ip == rth) && curr_frame >= 0) {
                                printk(" (%pS)",
                                       (void *)current->ret_stack[curr_frame].ret);
                                curr_frame--;
                        }
#endif
                        if (firstframe)
                                printk(" (unreliable)");
                        printk("\n");
                }
                firstframe = 0;

                /*
                 * See if this is an exception frame.
                 * We look for the "regshere" marker in the current frame.
                 */
                if (validate_sp(sp, tsk, STACK_INT_FRAME_SIZE)
                    && stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
                        struct pt_regs *regs = (struct pt_regs *)
                                (sp + STACK_FRAME_OVERHEAD);
                        lr = regs->link;
                        printk("--- interrupt: %lx at %pS\n    LR = %pS\n",
                               regs->trap, (void *)regs->nip, (void *)lr);
                        firstframe = 1;
                }

                sp = newsp;
        } while (count++ < kstack_depth_to_print);
}

#ifdef CONFIG_PPC64
/* Called with hard IRQs off */
void notrace __ppc64_runlatch_on(void)
{
        struct thread_info *ti = current_thread_info();
        unsigned long ctrl;

        ctrl = mfspr(SPRN_CTRLF);
        ctrl |= CTRL_RUNLATCH;
        mtspr(SPRN_CTRLT, ctrl);

        ti->local_flags |= _TLF_RUNLATCH;
}

/* Called with hard IRQs off */
void notrace __ppc64_runlatch_off(void)
{
        struct thread_info *ti = current_thread_info();
        unsigned long ctrl;

        ti->local_flags &= ~_TLF_RUNLATCH;

        ctrl = mfspr(SPRN_CTRLF);
        ctrl &= ~CTRL_RUNLATCH;
        mtspr(SPRN_CTRLT, ctrl);
}
#endif /* CONFIG_PPC64 */

unsigned long arch_align_stack(unsigned long sp)
{
        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
                sp -= get_random_int() & ~PAGE_MASK;
        return sp & ~0xf;
}

static inline unsigned long brk_rnd(void)
{
        unsigned long rnd = 0;

        /* 8MB for 32bit, 1GB for 64bit */
        if (is_32bit_task())
                rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));
        else
                rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));

        return rnd << PAGE_SHIFT;
}

unsigned long arch_randomize_brk(struct mm_struct *mm)
{
        unsigned long base = mm->brk;
        unsigned long ret;

#ifdef CONFIG_PPC_STD_MMU_64
        /*
         * If we are using 1TB segments and we are allowed to randomise
         * the heap, we can put it above 1TB so it is backed by a 1TB
         * segment. Otherwise the heap will be in the bottom 1TB
         * which always uses 256MB segments and this may result in a
         * performance penalty.
         */
        if (!is_32bit_task() && (mmu_highuser_ssize == MMU_SEGSIZE_1T))
                base = max_t(unsigned long, mm->brk, 1UL << SID_SHIFT_1T);
#endif

        ret = PAGE_ALIGN(base + brk_rnd());

        if (ret < mm->brk)
                return mm->brk;

        return ret;
}