/* SPDX-License-Identifier: GPL-2.0 */
/*
 *  S390 version
 *
 *  Derived from "include/asm-i386/mmu_context.h"
 */

#ifndef __S390_MMU_CONTEXT_H
#define __S390_MMU_CONTEXT_H

#include <asm/pgalloc.h>
#include <linux/uaccess.h>
#include <linux/mm_types.h>
#include <asm/tlbflush.h>
#include <asm/ctlreg.h>
#include <asm/asce.h>
#include <asm-generic/mm_hooks.h>

#define init_new_context init_new_context
static inline int init_new_context(struct task_struct *tsk,
                                   struct mm_struct *mm)
{
        unsigned long asce_type, init_entry;

        spin_lock_init(&mm->context.lock);
        INIT_LIST_HEAD(&mm->context.gmap_list);
        cpumask_clear(&mm->context.cpu_attach_mask);
        atomic_set(&mm->context.flush_count, 0);
        atomic_set(&mm->context.protected_count, 0);
        mm->context.gmap_asce = 0;
        mm->context.flush_mm = 0;
#if IS_ENABLED(CONFIG_KVM)
        mm->context.allow_cow_sharing = 1;
#endif
        switch (mm->context.asce_limit) {
        default:
                /*
                 * context created by exec, the value of asce_limit can
                 * only be zero in this case
                 */
                VM_BUG_ON(mm->context.asce_limit);
                /* continue as 3-level task */
                mm->context.asce_limit = _REGION2_SIZE;
                fallthrough;
        case _REGION2_SIZE:
                /* forked 3-level task */
                init_entry = _REGION3_ENTRY_EMPTY;
                asce_type = _ASCE_TYPE_REGION3;
                break;
        case TASK_SIZE_MAX:
                /* forked 5-level task */
                init_entry = _REGION1_ENTRY_EMPTY;
                asce_type = _ASCE_TYPE_REGION1;
                break;
        case _REGION1_SIZE:
                /* forked 4-level task */
                init_entry = _REGION2_ENTRY_EMPTY;
                asce_type = _ASCE_TYPE_REGION2;
                break;
        }
        mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
                           _ASCE_USER_BITS | asce_type;
        crst_table_init((unsigned long *) mm->pgd, init_entry);
        return 0;
}

static inline void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
                                      struct task_struct *tsk)
{
        int cpu = smp_processor_id();

        if (next == &init_mm)
                get_lowcore()->user_asce = s390_invalid_asce;
        else
                get_lowcore()->user_asce.val = next->context.asce;
        cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);
        /* Clear previous user-ASCE from CR1 and CR7 */
        local_ctl_load(1, &s390_invalid_asce);
        local_ctl_load(7, &s390_invalid_asce);
        if (prev != next)
                cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
}
#define switch_mm_irqs_off switch_mm_irqs_off

static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
                             struct task_struct *tsk)
{
        unsigned long flags;

        local_irq_save(flags);
        switch_mm_irqs_off(prev, next, tsk);
        local_irq_restore(flags);
}

#define finish_arch_post_lock_switch finish_arch_post_lock_switch
static inline void finish_arch_post_lock_switch(void)
{
        struct task_struct *tsk = current;
        struct mm_struct *mm = tsk->mm;
        unsigned long flags;

        if (mm) {
                preempt_disable();
                while (atomic_read(&mm->context.flush_count))
                        cpu_relax();
                cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
                __tlb_flush_mm_lazy(mm);
                preempt_enable();
        }
        local_irq_save(flags);
        if (test_thread_flag(TIF_ASCE_PRIMARY))
                local_ctl_load(1, &get_lowcore()->kernel_asce);
        else
                local_ctl_load(1, &get_lowcore()->user_asce);
        local_ctl_load(7, &get_lowcore()->user_asce);
        local_irq_restore(flags);
}

#define activate_mm activate_mm
static inline void activate_mm(struct mm_struct *prev,
                               struct mm_struct *next)
{
        switch_mm_irqs_off(prev, next, current);
        cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
        if (test_thread_flag(TIF_ASCE_PRIMARY))
                local_ctl_load(1, &get_lowcore()->kernel_asce);
        else
                local_ctl_load(1, &get_lowcore()->user_asce);
        local_ctl_load(7, &get_lowcore()->user_asce);
}

#include <asm-generic/mmu_context.h>

#endif /* __S390_MMU_CONTEXT_H */