/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2023 Arm Ltd.
 *
 * Based on arch/x86/include/asm/pkeys.h
 */

#ifndef _ASM_ARM64_PKEYS_H
#define _ASM_ARM64_PKEYS_H

#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2)

#define arch_max_pkey() 8

int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
                unsigned long init_val);

static inline bool arch_pkeys_enabled(void)
{
        return system_supports_poe();
}

static inline int vma_pkey(struct vm_area_struct *vma)
{
        return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
}

static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
                int prot, int pkey)
{
        if (pkey != -1)
                return pkey;

        return vma_pkey(vma);
}

static inline int execute_only_pkey(struct mm_struct *mm)
{
        // Execute-only mappings are handled by EPAN/FEAT_PAN3.
        return -1;
}

#define mm_pkey_allocation_map(mm)      (mm)->context.pkey_allocation_map
#define mm_set_pkey_allocated(mm, pkey) do {            \
        mm_pkey_allocation_map(mm) |= (1U << pkey);     \
} while (0)
#define mm_set_pkey_free(mm, pkey) do {                 \
        mm_pkey_allocation_map(mm) &= ~(1U << pkey);    \
} while (0)

static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
{
        /*
         * "Allocated" pkeys are those that have been returned
         * from pkey_alloc() or pkey 0 which is allocated
         * implicitly when the mm is created.
         */
        if (pkey < 0 || pkey >= arch_max_pkey())
                return false;

        return mm_pkey_allocation_map(mm) & (1U << pkey);
}

/*
 * Returns a positive, 3-bit key on success, or -1 on failure.
 */
static inline int mm_pkey_alloc(struct mm_struct *mm)
{
        /*
         * Note: this is the one and only place we make sure
         * that the pkey is valid as far as the hardware is
         * concerned.  The rest of the kernel trusts that
         * only good, valid pkeys come out of here.
         */
        u8 all_pkeys_mask = GENMASK(arch_max_pkey() - 1, 0);
        int ret;

        if (!arch_pkeys_enabled())
                return -1;

        /*
         * Are we out of pkeys?  We must handle this specially
         * because ffz() behavior is undefined if there are no
         * zeros.
         */
        if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
                return -1;

        ret = ffz(mm_pkey_allocation_map(mm));

        mm_set_pkey_allocated(mm, ret);

        return ret;
}

static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
{
        if (!mm_pkey_is_allocated(mm, pkey))
                return -EINVAL;

        mm_set_pkey_free(mm, pkey);

        return 0;
}

#endif /* _ASM_ARM64_PKEYS_H */