/* 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 __ASSEMBLER__

#ifdef CONFIG_PPC_KUAP

#include <linux/sched.h>

#define KUAP_NONE       (~0UL)

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

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

static __always_inline void uaccess_begin_32s(unsigned long addr)
{
        unsigned long tmp;

        asm volatile(ASM_MMU_FTR_IFSET(
                "mfsrin %0, %1;"
                "rlwinm %0, %0, 0, %2;"
                "mtsrin %0, %1;"
                "isync", "", %3)
                : "=&r"(tmp)
                : "r"(addr), "i"(~SR_KS), "i"(MMU_FTR_KUAP)
                : "memory");
}

static __always_inline void uaccess_end_32s(unsigned long addr)
{
        unsigned long tmp;

        asm volatile(ASM_MMU_FTR_IFSET(
                "mfsrin %0, %1;"
                "oris %0, %0, %2;"
                "mtsrin %0, %1;"
                "isync", "", %3)
                : "=&r"(tmp)
                : "r"(addr), "i"(SR_KS >> 16), "i"(MMU_FTR_KUAP)
                : "memory");
}

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

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

        current->thread.kuap = KUAP_NONE;
        kuap_lock_one(kuap);
}
#define __kuap_save_and_lock __kuap_save_and_lock

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

static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
{
        if (unlikely(kuap != KUAP_NONE)) {
                current->thread.kuap = KUAP_NONE;
                kuap_lock_one(kuap);
        }

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

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

        kuap_unlock_one(regs->kuap);
}

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

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

        return kuap;
}
#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked

static __always_inline void allow_user_access(void __user *to, unsigned long dir)
{
        BUILD_BUG_ON(!__builtin_constant_p(dir));

        if (!(dir & KUAP_WRITE))
                return;

        current->thread.kuap = (__force u32)to;
        uaccess_begin_32s((__force u32)to);
}

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

        BUILD_BUG_ON(!__builtin_constant_p(dir));

        if (!(dir & KUAP_WRITE))
                return;

        current->thread.kuap = KUAP_NONE;
        uaccess_end_32s(kuap);
}

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

        if (flags != KUAP_NONE) {
                current->thread.kuap = KUAP_NONE;
                uaccess_end_32s(flags);
        }

        return flags;
}

static __always_inline void restore_user_access(unsigned long flags)
{
        if (flags != KUAP_NONE) {
                current->thread.kuap = flags;
                uaccess_begin_32s(flags);
        }
}

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

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

        /*
         * If faulting address doesn't match unlocked segment, change segment.
         * In case of unaligned store crossing two segments, emulate store.
         */
        if ((kuap ^ address) & 0xf0000000) {
                if (!(kuap & 0x0fffffff) && address > kuap - 4 && fix_alignment(regs)) {
                        regs_add_return_ip(regs, 4);
                        emulate_single_step(regs);
                } else {
                        regs->kuap = address;
                }
        }

        return false;
}

#endif /* CONFIG_PPC_KUAP */

#endif /* __ASSEMBLER__ */

#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */