/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_BOOK3S_32_KUP_H
#define _ASM_POWERPC_BOOK3S_32_KUP_H

#include <asm/bug.h>
#include <asm/book3s/32/mmu-hash.h>
#include <asm/mmu.h>
#include <asm/synch.h>

#ifndef __ASSEMBLY__

#include <linux/jump_label.h>

extern struct static_key_false disable_kuap_key;
extern struct static_key_false disable_kuep_key;

static __always_inline bool kuap_is_disabled(void)
{
        return !IS_ENABLED(CONFIG_PPC_KUAP) || static_branch_unlikely(&disable_kuap_key);
}

static __always_inline bool kuep_is_disabled(void)
{
        return !IS_ENABLED(CONFIG_PPC_KUEP) || static_branch_unlikely(&disable_kuep_key);
}

static inline void kuep_lock(void)
{
        if (kuep_is_disabled())
                return;

        update_user_segments(mfsr(0) | SR_NX);
        /*
         * This isync() shouldn't be necessary as the kernel is not excepted to
         * run any instruction in userspace soon after the update of segments,
         * but hash based cores (at least G3) seem to exhibit a random
         * behaviour when the 'isync' is not there. 603 cores don't have this
         * behaviour so don't do the 'isync' as it saves several CPU cycles.
         */
        if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
                isync();        /* Context sync required after mtsr() */
}

static inline void kuep_unlock(void)
{
        if (kuep_is_disabled())
                return;

        update_user_segments(mfsr(0) & ~SR_NX);
        /*
         * This isync() shouldn't be necessary as a 'rfi' will soon be executed
         * to return to userspace, but hash based cores (at least G3) seem to
         * exhibit a random behaviour when the 'isync' is not there. 603 cores
         * don't have this behaviour so don't do the 'isync' as it saves several
         * CPU cycles.
         */
        if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
                isync();        /* Context sync required after mtsr() */
}

#ifdef CONFIG_PPC_KUAP

#include <linux/sched.h>

#define KUAP_NONE       (~0UL)
#define KUAP_ALL        (~1UL)

static inline void kuap_lock_one(unsigned long addr)
{
        mtsr(mfsr(addr) | SR_KS, addr);
        isync();        /* Context sync required after mtsr() */
}

static inline void kuap_unlock_one(unsigned long addr)
{
        mtsr(mfsr(addr) & ~SR_KS, addr);
        isync();        /* Context sync required after mtsr() */
}

static inline void kuap_lock_all(void)
{
        update_user_segments(mfsr(0) | SR_KS);
        isync();        /* Context sync required after mtsr() */
}

static inline void kuap_unlock_all(void)
{
        update_user_segments(mfsr(0) & ~SR_KS);
        isync();        /* Context sync required after mtsr() */
}

void kuap_lock_all_ool(void);
void kuap_unlock_all_ool(void);

static inline void kuap_lock(unsigned long addr, bool ool)
{
        if (likely(addr != KUAP_ALL))
                kuap_lock_one(addr);
        else if (!ool)
                kuap_lock_all();
        else
                kuap_lock_all_ool();
}

static inline void kuap_unlock(unsigned long addr, bool ool)
{
        if (likely(addr != KUAP_ALL))
                kuap_unlock_one(addr);
        else if (!ool)
                kuap_unlock_all();
        else
                kuap_unlock_all_ool();
}

static inline void kuap_save_and_lock(struct pt_regs *regs)
{
        unsigned long kuap = current->thread.kuap;

        if (kuap_is_disabled())
                return;

        regs->kuap = kuap;
        if (unlikely(kuap == KUAP_NONE))
                return;

        current->thread.kuap = KUAP_NONE;
        kuap_lock(kuap, false);
}

static inline void kuap_user_restore(struct pt_regs *regs)
{
}

static inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
{
        if (kuap_is_disabled())
                return;

        if (unlikely(kuap != KUAP_NONE)) {
                current->thread.kuap = KUAP_NONE;
                kuap_lock(kuap, false);
        }

        if (likely(regs->kuap == KUAP_NONE))
                return;

        current->thread.kuap = regs->kuap;

        kuap_unlock(regs->kuap, false);
}

static inline unsigned long kuap_get_and_assert_locked(void)
{
        unsigned long kuap = current->thread.kuap;

        if (kuap_is_disabled())
                return KUAP_NONE;

        WARN_ON_ONCE(IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && kuap != KUAP_NONE);

        return kuap;
}

static inline void kuap_assert_locked(void)
{
        kuap_get_and_assert_locked();
}

static __always_inline void allow_user_access(void __user *to, const void __user *from,
                                              u32 size, unsigned long dir)
{
        if (kuap_is_disabled())
                return;

        BUILD_BUG_ON(!__builtin_constant_p(dir));

        if (!(dir & KUAP_WRITE))
                return;

        current->thread.kuap = (__force u32)to;
        kuap_unlock_one((__force u32)to);
}

static __always_inline void prevent_user_access(unsigned long dir)
{
        u32 kuap = current->thread.kuap;

        if (kuap_is_disabled())
                return;

        BUILD_BUG_ON(!__builtin_constant_p(dir));

        if (!(dir & KUAP_WRITE))
                return;

        current->thread.kuap = KUAP_NONE;
        kuap_lock(kuap, true);
}

static inline unsigned long prevent_user_access_return(void)
{
        unsigned long flags = current->thread.kuap;

        if (kuap_is_disabled())
                return KUAP_NONE;

        if (flags != KUAP_NONE) {
                current->thread.kuap = KUAP_NONE;
                kuap_lock(flags, true);
        }

        return flags;
}

static inline void restore_user_access(unsigned long flags)
{
        if (kuap_is_disabled())
                return;

        if (flags != KUAP_NONE) {
                current->thread.kuap = flags;
                kuap_unlock(flags, true);
        }
}

static inline bool
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
        unsigned long kuap = regs->kuap;

        if (kuap_is_disabled())
                return false;

        if (!is_write || kuap == KUAP_ALL)
                return false;
        if (kuap == KUAP_NONE)
                return true;

        /* If faulting address doesn't match unlocked segment, unlock all */
        if ((kuap ^ address) & 0xf0000000)
                regs->kuap = KUAP_ALL;

        return false;
}

#endif /* CONFIG_PPC_KUAP */

#endif /* __ASSEMBLY__ */

#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */