/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_PKEYS_H
#define _ASM_X86_PKEYS_H

/*
 * If more than 16 keys are ever supported, a thorough audit
 * will be necessary to ensure that the types that store key
 * numbers and masks have sufficient capacity.
 */
#define arch_max_pkey() (cpu_feature_enabled(X86_FEATURE_OSPKE) ? 16 : 1)

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

static inline bool arch_pkeys_enabled(void)
{
        return cpu_feature_enabled(X86_FEATURE_OSPKE);
}

/*
 * Try to dedicate one of the protection keys to be used as an
 * execute-only protection key.
 */
extern int __execute_only_pkey(struct mm_struct *mm);
static inline int execute_only_pkey(struct mm_struct *mm)
{
        if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
                return ARCH_DEFAULT_PKEY;

        return __execute_only_pkey(mm);
}

extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
                int prot, int pkey);
static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
                int prot, int pkey)
{
        if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
                return 0;

        return __arch_override_mprotect_pkey(vma, prot, pkey);
}

#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)

#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)
                return false;
        if (pkey >= arch_max_pkey())
                return false;
        /*
         * The exec-only pkey is set in the allocation map, but
         * is not available to any of the user interfaces like
         * mprotect_pkey().
         */
        if (pkey == mm->context.execute_only_pkey)
                return false;

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

/*
 * Returns a positive, 4-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.
         */
        u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
        int ret;

        /*
         * 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;
}

static inline int vma_pkey(struct vm_area_struct *vma)
{
        unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
                                      VM_PKEY_BIT2 | VM_PKEY_BIT3;

        return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
}

#endif /*_ASM_X86_PKEYS_H */