Merge tag 'samsung-soc-5.10' of https://git.kernel.org/pub/scm/linux/kernel/git/krzk...

[linux-2.6-microblaze.git] / arch / powerpc / kernel / process.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  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)
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.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 <linux/elf-randomize.h>
#include <linux/pkeys.h>
#include <linux/seq_buf.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>
#include <asm/hw_irq.h>
#endif
#include <asm/code-patching.h>
#include <asm/exec.h>
#include <asm/livepatch.h>
#include <asm/cpu_has_feature.h>
#include <asm/asm-prototypes.h>
#include <asm/stacktrace.h>
#include <asm/hw_breakpoint.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
/*
 * Are we running in "Suspend disabled" mode? If so we have to block any
 * sigreturn that would get us into suspended state, and we also warn in some
 * other paths that we should never reach with suspend disabled.
 */
bool tm_suspend_disabled __ro_after_init = false;

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);

/* notrace because it's called by restore_math */
unsigned long notrace 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);

        return newmsr;
}
EXPORT_SYMBOL_GPL(msr_check_and_set);

/* notrace because it's called by restore_math */
void notrace __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
static void __giveup_fpu(struct task_struct *tsk)
{
        unsigned long msr;

        save_fpu(tsk);
        msr = tsk->thread.regs->msr;
        msr &= ~(MSR_FP|MSR_FE0|MSR_FE1);
#ifdef CONFIG_VSX
        if (cpu_has_feature(CPU_FTR_VSX))
                msr &= ~MSR_VSX;
#endif
        tsk->thread.regs->msr = msr;
}

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)
{
        unsigned long cpumsr;

        WARN_ON(preemptible());

        cpumsr = msr_check_and_set(MSR_FP);

        if (current->thread.regs && (current->thread.regs->msr & MSR_FP)) {
                check_if_tm_restore_required(current);
                /*
                 * If a thread has already been reclaimed then the
                 * checkpointed registers are on the CPU but have definitely
                 * been saved by the reclaim code. Don't need to and *cannot*
                 * giveup as this would save  to the 'live' structure not the
                 * checkpointed structure.
                 */
                if (!MSR_TM_ACTIVE(cpumsr) &&
                     MSR_TM_ACTIVE(current->thread.regs->msr))
                        return;
                __giveup_fpu(current);
        }
}
EXPORT_SYMBOL(enable_kernel_fp);
#endif /* CONFIG_PPC_FPU */

#ifdef CONFIG_ALTIVEC
static void __giveup_altivec(struct task_struct *tsk)
{
        unsigned long msr;

        save_altivec(tsk);
        msr = tsk->thread.regs->msr;
        msr &= ~MSR_VEC;
#ifdef CONFIG_VSX
        if (cpu_has_feature(CPU_FTR_VSX))
                msr &= ~MSR_VSX;
#endif
        tsk->thread.regs->msr = msr;
}

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)
{
        unsigned long cpumsr;

        WARN_ON(preemptible());

        cpumsr = msr_check_and_set(MSR_VEC);

        if (current->thread.regs && (current->thread.regs->msr & MSR_VEC)) {
                check_if_tm_restore_required(current);
                /*
                 * If a thread has already been reclaimed then the
                 * checkpointed registers are on the CPU but have definitely
                 * been saved by the reclaim code. Don't need to and *cannot*
                 * giveup as this would save  to the 'live' structure not the
                 * checkpointed structure.
                 */
                if (!MSR_TM_ACTIVE(cpumsr) &&
                     MSR_TM_ACTIVE(current->thread.regs->msr))
                        return;
                __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
static void __giveup_vsx(struct task_struct *tsk)
{
        unsigned long msr = tsk->thread.regs->msr;

        /*
         * We should never be ssetting MSR_VSX without also setting
         * MSR_FP and MSR_VEC
         */
        WARN_ON((msr & MSR_VSX) && !((msr & MSR_FP) && (msr & MSR_VEC)));

        /* __giveup_fpu will clear MSR_VSX */
        if (msr & MSR_FP)
                __giveup_fpu(tsk);
        if (msr & MSR_VEC)
                __giveup_altivec(tsk);
}

static void giveup_vsx(struct task_struct *tsk)
{
        check_if_tm_restore_required(tsk);

        msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
        __giveup_vsx(tsk);
        msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
}

void enable_kernel_vsx(void)
{
        unsigned long cpumsr;

        WARN_ON(preemptible());

        cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);

        if (current->thread.regs &&
            (current->thread.regs->msr & (MSR_VSX|MSR_VEC|MSR_FP))) {
                check_if_tm_restore_required(current);
                /*
                 * If a thread has already been reclaimed then the
                 * checkpointed registers are on the CPU but have definitely
                 * been saved by the reclaim code. Don't need to and *cannot*
                 * giveup as this would save  to the 'live' structure not the
                 * checkpointed structure.
                 */
                if (!MSR_TM_ACTIVE(cpumsr) &&
                     MSR_TM_ACTIVE(current->thread.regs->msr))
                        return;
                __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|MSR_VEC|MSR_FP)) {
                        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;

        check_if_tm_restore_required(tsk);

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

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

        msr_check_and_set(msr_all_available);

        WARN_ON((usermsr & MSR_VSX) && !((usermsr & MSR_FP) && (usermsr & MSR_VEC)));

#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_SPE
        if (usermsr & MSR_SPE)
                __giveup_spe(tsk);
#endif

        msr_check_and_clear(msr_all_available);
}
EXPORT_SYMBOL(giveup_all);

#ifdef CONFIG_PPC_BOOK3S_64
#ifdef CONFIG_PPC_FPU
static bool should_restore_fp(void)
{
        if (current->thread.load_fp) {
                current->thread.load_fp++;
                return true;
        }
        return false;
}

static void do_restore_fp(void)
{
        load_fp_state(&current->thread.fp_state);
}
#else
static bool should_restore_fp(void) { return false; }
static void do_restore_fp(void) { }
#endif /* CONFIG_PPC_FPU */

#ifdef CONFIG_ALTIVEC
static bool should_restore_altivec(void)
{
        if (cpu_has_feature(CPU_FTR_ALTIVEC) && (current->thread.load_vec)) {
                current->thread.load_vec++;
                return true;
        }
        return false;
}

static void do_restore_altivec(void)
{
        load_vr_state(&current->thread.vr_state);
        current->thread.used_vr = 1;
}
#else
static bool should_restore_altivec(void) { return false; }
static void do_restore_altivec(void) { }
#endif /* CONFIG_ALTIVEC */

#ifdef CONFIG_VSX
static bool should_restore_vsx(void)
{
        if (cpu_has_feature(CPU_FTR_VSX))
                return true;
        return false;
}
static void do_restore_vsx(void)
{
        current->thread.used_vsr = 1;
}
#else
static bool should_restore_vsx(void) { return false; }
static void do_restore_vsx(void) { }
#endif /* CONFIG_VSX */

/*
 * The exception exit path calls restore_math() with interrupts hard disabled
 * but the soft irq state not "reconciled". ftrace code that calls
 * local_irq_save/restore causes warnings.
 *
 * Rather than complicate the exit path, just don't trace restore_math. This
 * could be done by having ftrace entry code check for this un-reconciled
 * condition where MSR[EE]=0 and PACA_IRQ_HARD_DIS is not set, and
 * temporarily fix it up for the duration of the ftrace call.
 */
void notrace restore_math(struct pt_regs *regs)
{
        unsigned long msr;
        unsigned long new_msr = 0;

        msr = regs->msr;

        /*
         * new_msr tracks the facilities that are to be restored. Only reload
         * if the bit is not set in the user MSR (if it is set, the registers
         * are live for the user thread).
         */
        if ((!(msr & MSR_FP)) && should_restore_fp())
                new_msr |= MSR_FP;

        if ((!(msr & MSR_VEC)) && should_restore_altivec())
                new_msr |= MSR_VEC;

        if ((!(msr & MSR_VSX)) && should_restore_vsx()) {
                if (((msr | new_msr) & (MSR_FP | MSR_VEC)) == (MSR_FP | MSR_VEC))
                        new_msr |= MSR_VSX;
        }

        if (new_msr) {
                unsigned long fpexc_mode = 0;

                msr_check_and_set(new_msr);

                if (new_msr & MSR_FP) {
                        do_restore_fp();

                        // This also covers VSX, because VSX implies FP
                        fpexc_mode = current->thread.fpexc_mode;
                }

                if (new_msr & MSR_VEC)
                        do_restore_altivec();

                if (new_msr & MSR_VSX)
                        do_restore_vsx();

                msr_check_and_clear(new_msr);

                regs->msr |= new_msr | fpexc_mode;
        }
}
#endif

static void save_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);

        WARN_ON((usermsr & MSR_VSX) && !((usermsr & MSR_FP) && (usermsr & MSR_VEC)));

        if (usermsr & MSR_FP)
                save_fpu(tsk);

        if (usermsr & MSR_VEC)
                save_altivec(tsk);

        if (usermsr & MSR_SPE)
                __giveup_spe(tsk);

        msr_check_and_clear(msr_all_available);
        thread_pkey_regs_save(&tsk->thread);
}

void flush_all_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                BUG_ON(tsk != current);
#ifdef CONFIG_SPE
                if (tsk->thread.regs->msr & MSR_SPE)
                        tsk->thread.spefscr = mfspr(SPRN_SPEFSCR);
#endif
                save_all(tsk);

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

        /* Deliver the signal to userspace */
        force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */
                                    (void __user *)address);
}
#else   /* !CONFIG_PPC_ADV_DEBUG_REGS */
void do_break (struct pt_regs *regs, unsigned long address,
                    unsigned long error_code)
{
        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;

        /* Deliver the signal to userspace */
        force_sig_fault(SIGTRAP, TRAP_HWBKPT, (void __user *)address);
}
#endif  /* CONFIG_PPC_ADV_DEBUG_REGS */

static DEFINE_PER_CPU(struct arch_hw_breakpoint, current_brk[HBP_NUM_MAX]);

#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_breakpoint(int i, struct arch_hw_breakpoint *brk)
{
        preempt_disable();
        __set_breakpoint(i, brk);
        preempt_enable();
}

static void set_debug_reg_defaults(struct thread_struct *thread)
{
        int i;
        struct arch_hw_breakpoint null_brk = {0};

        for (i = 0; i < nr_wp_slots(); i++) {
                thread->hw_brk[i] = null_brk;
                if (ppc_breakpoint_available())
                        set_breakpoint(i, &thread->hw_brk[i]);
        }
}

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;
        /* no need to check hw_len. it's calculated from address and len */
        return true;
}

static void switch_hw_breakpoint(struct task_struct *new)
{
        int i;

        for (i = 0; i < nr_wp_slots(); i++) {
                if (likely(hw_brk_match(this_cpu_ptr(&current_brk[i]),
                                        &new->thread.hw_brk[i])))
                        continue;

                __set_breakpoint(i, &new->thread.hw_brk[i]);
        }
}
#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_breakpoint_8xx(struct arch_hw_breakpoint *brk)
{
        unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
                               LCTRL1_CRWF_RW;
        unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
        unsigned long start_addr = ALIGN_DOWN(brk->address, HW_BREAKPOINT_SIZE);
        unsigned long end_addr = ALIGN(brk->address + brk->len, HW_BREAKPOINT_SIZE);

        if (start_addr == 0)
                lctrl2 |= LCTRL2_LW0LA_F;
        else if (end_addr == 0)
                lctrl2 |= LCTRL2_LW0LA_E;
        else
                lctrl2 |= LCTRL2_LW0LA_EandF;

        mtspr(SPRN_LCTRL2, 0);

        if ((brk->type & HW_BRK_TYPE_RDWR) == 0)
                return 0;

        if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_READ)
                lctrl1 |= LCTRL1_CRWE_RO | LCTRL1_CRWF_RO;
        if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_WRITE)
                lctrl1 |= LCTRL1_CRWE_WO | LCTRL1_CRWF_WO;

        mtspr(SPRN_CMPE, start_addr - 1);
        mtspr(SPRN_CMPF, end_addr);
        mtspr(SPRN_LCTRL1, lctrl1);
        mtspr(SPRN_LCTRL2, lctrl2);

        return 0;
}

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

        if (dawr_enabled())
                // Power8 or later
                set_dawr(nr, brk);
        else if (IS_ENABLED(CONFIG_PPC_8xx))
                set_breakpoint_8xx(brk);
        else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
                // Power7 or earlier
                set_dabr(brk);
        else
                // Shouldn't happen due to higher level checks
                WARN_ON_ONCE(1);
}

/* Check if we have DAWR or DABR hardware */
bool ppc_breakpoint_available(void)
{
        if (dawr_enabled())
                return true; /* POWER8 DAWR or POWER9 forced DAWR */
        if (cpu_has_feature(CPU_FTR_ARCH_207S))
                return false; /* POWER9 with DAWR disabled */
        /* DABR: Everything but POWER8 and POWER9 */
        return true;
}
EXPORT_SYMBOL_GPL(ppc_breakpoint_available);

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM

static inline bool tm_enabled(struct task_struct *tsk)
{
        return tsk && tsk->thread.regs && (tsk->thread.regs->msr & MSR_TM);
}

static void tm_reclaim_thread(struct thread_struct *thr, uint8_t cause)
{
        /*
         * 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
         * benefit of checking for a potential TM bad thing exception.
         */
        if (!MSR_TM_SUSPENDED(mfmsr()))
                return;

        giveup_all(container_of(thr, struct task_struct, thread));

        tm_reclaim(thr, cause);

        /*
         * If we are in a transaction and FP is off then we can't have
         * used FP inside that transaction. Hence the checkpointed
         * state is the same as the live state. We need to copy the
         * live state to the checkpointed state so that when the
         * transaction is restored, the checkpointed state is correct
         * and the aborted transaction sees the correct state. We use
         * ckpt_regs.msr here as that's what tm_reclaim will use to
         * determine if it's going to write the checkpointed state or
         * not. So either this will write the checkpointed registers,
         * or reclaim will. Similarly for VMX.
         */
        if ((thr->ckpt_regs.msr & MSR_FP) == 0)
                memcpy(&thr->ckfp_state, &thr->fp_state,
                       sizeof(struct thread_fp_state));
        if ((thr->ckpt_regs.msr & MSR_VEC) == 0)
                memcpy(&thr->ckvr_state, &thr->vr_state,
                       sizeof(struct thread_vr_state));
}

void tm_reclaim_current(uint8_t cause)
{
        tm_enable();
        tm_reclaim_thread(&current->thread, 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, ckfp_state and
         * ckvr_state
         *
         * 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;

        WARN_ON(tm_suspend_disabled);

        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, 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);

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

        if (!(thread->regs->msr & MSR_TM))
                return;

        /* 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);

        local_irq_restore(flags);
}

static inline void tm_recheckpoint_new_task(struct task_struct *new)
{
        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
         * unavailable later, we are unable to determine which set of FP regs
         * need to be restored.
         */
        if (!tm_enabled(new))
                return;

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

        tm_recheckpoint(&new->thread);

        /*
         * The checkpointed state has been restored but the live state has
         * not, ensure all the math functionality is turned off to trigger
         * restore_math() to reload.
         */
        new->thread.regs->msr &= ~(MSR_FP | MSR_VEC | 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,
                struct task_struct *new)
{
        if (cpu_has_feature(CPU_FTR_TM)) {
                if (tm_enabled(prev) || tm_enabled(new))
                        tm_enable();

                if (tm_enabled(prev)) {
                        prev->thread.load_tm++;
                        tm_reclaim_task(prev);
                        if (!MSR_TM_ACTIVE(prev->thread.regs->msr) && prev->thread.load_tm == 0)
                                prev->thread.regs->msr &= ~MSR_TM;
                }

                tm_recheckpoint_new_task(new);
        }
}

/*
 * 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;

        /*
         * This is the only moment we should clear TIF_RESTORE_TM as
         * it is here that ckpt_regs.msr and pt_regs.msr become the same
         * again, anything else could lead to an incorrect ckpt_msr being
         * saved and therefore incorrect signal contexts.
         */
        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;

        /* Ensure that restore_math() will restore */
        if (msr_diff & MSR_FP)
                current->thread.load_fp = 1;
#ifdef CONFIG_ALTIVEC
        if (cpu_has_feature(CPU_FTR_ALTIVEC) && msr_diff & MSR_VEC)
                current->thread.load_vec = 1;
#endif
        restore_math(regs);

        regs->msr |= msr_diff;
}

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

static inline void save_sprs(struct thread_struct *t)
{
#ifdef CONFIG_ALTIVEC
        if (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

        thread_pkey_regs_save(t);
}

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;
                if (new_thread->dscr_inherit)
                        dscr = new_thread->dscr;

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

        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->fscr != new_thread->fscr)
                        mtspr(SPRN_FSCR, new_thread->fscr);

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

        if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
            old_thread->tidr != new_thread->tidr)
                mtspr(SPRN_TIDR, new_thread->tidr);
#endif

        thread_pkey_regs_restore(new_thread, old_thread);
}

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_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
        switch_hw_breakpoint(new);
#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);

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

        __switch_to_tm(prev, new);

        if (!radix_enabled()) {
                /*
                 * 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();
        }

        /*
         * 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;
        }

        if (current->thread.regs) {
                restore_math(current->thread.regs);

                /*
                 * The copy-paste buffer can only store into foreign real
                 * addresses, so unprivileged processes can not see the
                 * data or use it in any way unless they have foreign real
                 * mappings. If the new process has the foreign real address
                 * mappings, we must issue a cp_abort to clear any state and
                 * prevent snooping, corruption or a covert channel.
                 */
                if (current->mm &&
                        atomic_read(&current->mm->context.vas_windows))
                        asm volatile(PPC_CP_ABORT);
        }
#endif /* CONFIG_PPC_BOOK3S_64 */

        return last;
}

#define NR_INSN_TO_PRINT        16

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

        printk("Instruction dump:");

        /*
         * If we were executing with the MMU off for instructions, adjust pc
         * rather than printing XXXXXXXX.
         */
        if (!IS_ENABLED(CONFIG_BOOKE) && !(regs->msr & MSR_IR)) {
                pc = (unsigned long)phys_to_virt(pc);
                nip = (unsigned long)phys_to_virt(regs->nip);
        }

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

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

                if (!__kernel_text_address(pc) ||
                    get_kernel_nofault(instr, (const void *)pc)) {
                        pr_cont("XXXXXXXX ");
                } else {
                        if (nip == pc)
                                pr_cont("<%08x> ", instr);
                        else
                                pr_cont("%08x ", instr);
                }

                pc += sizeof(int);
        }

        pr_cont("\n");
}

void show_user_instructions(struct pt_regs *regs)
{
        unsigned long pc;
        int n = NR_INSN_TO_PRINT;
        struct seq_buf s;
        char buf[96]; /* enough for 8 times 9 + 2 chars */

        pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));

        seq_buf_init(&s, buf, sizeof(buf));

        while (n) {
                int i;

                seq_buf_clear(&s);

                for (i = 0; i < 8 && n; i++, n--, pc += sizeof(int)) {
                        int instr;

                        if (copy_from_user_nofault(&instr, (void __user *)pc,
                                        sizeof(instr))) {
                                seq_buf_printf(&s, "XXXXXXXX ");
                                continue;
                        }
                        seq_buf_printf(&s, regs->nip == pc ? "<%08x> " : "%08x ", instr);
                }

                if (!seq_buf_has_overflowed(&s))
                        pr_info("%s[%d]: code: %s\n", current->comm,
                                current->pid, s.buffer);
        }
}

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) {
                        pr_cont("%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)) {
                pr_cont(",TM[");
                print_bits(val, msr_tm_bits, "");
                pr_cont("]");
        }
}
#else
static void print_tm_bits(unsigned long val) {}
#endif

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

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

        for (i = 0;  i < 32;  i++) {
                if ((i % REGS_PER_LINE) == 0)
                        pr_cont("\nGPR%02d: ", i);
                pr_cont(REG " ", regs->gpr[i]);
                if (i == LAST_VOLATILE && !FULL_REGS(regs))
                        break;
        }
        pr_cont("\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], KERN_DEFAULT);
        if (!user_mode(regs))
                show_instructions(regs);
}

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 */
}

#ifdef CONFIG_PPC_BOOK3S_64
void arch_setup_new_exec(void)
{
        if (radix_enabled())
                return;
        hash__setup_new_exec();
}
#endif

#ifdef CONFIG_PPC64
/**
 * Assign a TIDR (thread ID) for task @t and set it in the thread
 * structure. For now, we only support setting TIDR for 'current' task.
 *
 * Since the TID value is a truncated form of it PID, it is possible
 * (but unlikely) for 2 threads to have the same TID. In the unlikely event
 * that 2 threads share the same TID and are waiting, one of the following
 * cases will happen:
 *
 * 1. The correct thread is running, the wrong thread is not
 * In this situation, the correct thread is woken and proceeds to pass it's
 * condition check.
 *
 * 2. Neither threads are running
 * In this situation, neither thread will be woken. When scheduled, the waiting
 * threads will execute either a wait, which will return immediately, followed
 * by a condition check, which will pass for the correct thread and fail
 * for the wrong thread, or they will execute the condition check immediately.
 *
 * 3. The wrong thread is running, the correct thread is not
 * The wrong thread will be woken, but will fail it's condition check and
 * re-execute wait. The correct thread, when scheduled, will execute either
 * it's condition check (which will pass), or wait, which returns immediately
 * when called the first time after the thread is scheduled, followed by it's
 * condition check (which will pass).
 *
 * 4. Both threads are running
 * Both threads will be woken. The wrong thread will fail it's condition check
 * and execute another wait, while the correct thread will pass it's condition
 * check.
 *
 * @t: the task to set the thread ID for
 */
int set_thread_tidr(struct task_struct *t)
{
        if (!cpu_has_feature(CPU_FTR_P9_TIDR))
                return -EINVAL;

        if (t != current)
                return -EINVAL;

        if (t->thread.tidr)
                return 0;

        t->thread.tidr = (u16)task_pid_nr(t);
        mtspr(SPRN_TIDR, t->thread.tidr);

        return 0;
}
EXPORT_SYMBOL_GPL(set_thread_tidr);

#endif /* CONFIG_PPC64 */

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.
         *
         * Can't pass dst because it isn't ready. Doesn't matter, passing
         * dst is only important for __switch_to()
         */
        __switch_to_tm(src, src);

        *dst = *src;

        clear_task_ebb(dst);

        return 0;
}

static void setup_ksp_vsid(struct task_struct *p, unsigned long sp)
{
#ifdef CONFIG_PPC_BOOK3S_64
        unsigned long sp_vsid;
        unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;

        if (radix_enabled())
                return;

        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,
                unsigned long tls)
{
        struct pt_regs *childregs, *kregs;
        extern void ret_from_fork(void);
        extern void ret_from_fork_scv(void);
        extern void ret_from_kernel_thread(void);
        void (*f)(void);
        unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
        struct thread_info *ti = task_thread_info(p);
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        int i;
#endif

        klp_init_thread_info(p);

        /* Copy registers */
        sp -= sizeof(struct pt_regs);
        childregs = (struct pt_regs *) sp;
        if (unlikely(p->flags & PF_KTHREAD)) {
                /* kernel thread */
                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 = IRQS_ENABLED;
#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;
                /* 64s sets this in ret_from_fork */
                if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64))
                        childregs->gpr[3] = 0;  /* Result from fork() */
                if (clone_flags & CLONE_SETTLS) {
                        if (!is_32bit_task())
                                childregs->gpr[13] = tls;
                        else
                                childregs->gpr[2] = tls;
                }

                if (trap_is_scv(regs))
                        f = ret_from_fork_scv;
                else
                        f = ret_from_fork;
        }
        childregs->msr &= ~(MSR_FP|MSR_VEC|MSR_VSX);
        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)end_of_stack(p);
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        for (i = 0; i < nr_wp_slots(); i++)
                p->thread.ptrace_bps[i] = 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))
                childregs->ppr = DEFAULT_PPR;

        p->thread.tidr = 0;
#endif
        kregs->nip = ppc_function_entry(f);
        return 0;
}

void preload_new_slb_context(unsigned long start, unsigned long sp);

/*
 * 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 */

#ifdef CONFIG_PPC_BOOK3S_64
        if (!radix_enabled())
                preload_new_slb_context(start, sp);
#endif
#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;
        }

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        /*
         * Clear any transactional state, we're exec()ing. The cause is
         * not important as there will never be a recheckpoint so it's not
         * user visible.
         */
        if (MSR_TM_SUSPENDED(mfmsr()))
                tm_reclaim_current(0);
#endif

        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.
         */
        SET_FULL_REGS(regs);

#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
        current->thread.load_slb = 0;
        current->thread.load_fp = 0;
        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;
        current->thread.load_vec = 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
        current->thread.tm_tfhar = 0;
        current->thread.tm_texasr = 0;
        current->thread.tm_tfiar = 0;
        current->thread.load_tm = 0;
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */

        thread_pkey_regs_init(&current->thread);
}
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);

        stack_page = (unsigned long)hardirq_ctx[cpu];
        if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

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

        return 0;
}

static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
                                        unsigned long nbytes)
{
#ifdef CONFIG_PPC64
        unsigned long stack_page;
        unsigned long cpu = task_cpu(p);

        stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE;
        if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

# ifdef CONFIG_PPC_BOOK3S_64
        stack_page = (unsigned long)paca_ptrs[cpu]->nmi_emergency_sp - THREAD_SIZE;
        if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

        stack_page = (unsigned long)paca_ptrs[cpu]->mc_emergency_sp - THREAD_SIZE;
        if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;
# endif
#endif

        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 < THREAD_SIZE)
                return 0;

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

        if (valid_irq_stack(sp, p, nbytes))
                return 1;

        return valid_emergency_stack(sp, p, nbytes);
}

EXPORT_SYMBOL(validate_sp);

static 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) ||
                    p->state == TASK_RUNNING)
                        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;
}

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long ret;

        if (!try_get_task_stack(p))
                return 0;

        ret = __get_wchan(p);

        put_task_stack(p);

        return ret;
}

static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;

void show_stack(struct task_struct *tsk, unsigned long *stack,
                const char *loglvl)
{
        unsigned long sp, ip, lr, newsp;
        int count = 0;
        int firstframe = 1;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        unsigned long ret_addr;
        int ftrace_idx = 0;
#endif

        if (tsk == NULL)
                tsk = current;

        if (!try_get_task_stack(tsk))
                return;

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

        lr = 0;
        printk("%sCall Trace:\n", loglvl);
        do {
                if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
                        break;

                stack = (unsigned long *) sp;
                newsp = stack[0];
                ip = stack[STACK_FRAME_LR_SAVE];
                if (!firstframe || ip != lr) {
                        printk("%s["REG"] ["REG"] %pS",
                                loglvl, sp, ip, (void *)ip);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
                        ret_addr = ftrace_graph_ret_addr(current,
                                                &ftrace_idx, ip, stack);
                        if (ret_addr != ip)
                                pr_cont(" (%pS)", (void *)ret_addr);
#endif
                        if (firstframe)
                                pr_cont(" (unreliable)");
                        pr_cont("\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("%s--- interrupt: %lx at %pS\n    LR = %pS\n",
                               loglvl, regs->trap,
                               (void *)regs->nip, (void *)lr);
                        firstframe = 1;
                }

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

        put_task_stack(tsk);
}

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

        if (cpu_has_feature(CPU_FTR_ARCH_206)) {
                /*
                 * Least significant bit (RUN) is the only writable bit of
                 * the CTRL register, so we can avoid mfspr. 2.06 is not the
                 * earliest ISA where this is the case, but it's convenient.
                 */
                mtspr(SPRN_CTRLT, CTRL_RUNLATCH);
        } else {
                unsigned long ctrl;

                /*
                 * Some architectures (e.g., Cell) have writable fields other
                 * than RUN, so do the read-modify-write.
                 */
                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();

        ti->local_flags &= ~_TLF_RUNLATCH;

        if (cpu_has_feature(CPU_FTR_ARCH_206)) {
                mtspr(SPRN_CTRLT, 0);
        } else {
                unsigned long ctrl;

                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 = (get_random_long() % (1UL<<(23-PAGE_SHIFT)));
        else
                rnd = (get_random_long() % (1UL<<(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_BOOK3S_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. We don't need to worry about radix. For
         * radix, mmu_highuser_ssize remains unchanged from 256MB.
         */
        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;
}