// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
 * Adapted from arch/arm64/kernel/efi.c
 */

#include <linux/efi.h>
#include <linux/init.h>

#include <asm/efi.h>
#include <asm/pgtable.h>
#include <asm/pgtable-bits.h>

/*
 * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
 * executable, everything else can be mapped with the XN bits
 * set. Also take the new (optional) RO/XP bits into account.
 */
static __init pgprot_t efimem_to_pgprot_map(efi_memory_desc_t *md)
{
        u64 attr = md->attribute;
        u32 type = md->type;

        if (type == EFI_MEMORY_MAPPED_IO)
                return PAGE_KERNEL;

        /* R-- */
        if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
            (EFI_MEMORY_XP | EFI_MEMORY_RO))
                return PAGE_KERNEL_READ;

        /* R-X */
        if (attr & EFI_MEMORY_RO)
                return PAGE_KERNEL_READ_EXEC;

        /* RW- */
        if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==
             EFI_MEMORY_XP) ||
            type != EFI_RUNTIME_SERVICES_CODE)
                return PAGE_KERNEL;

        /* RWX */
        return PAGE_KERNEL_EXEC;
}

int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
{
        pgprot_t prot = __pgprot(pgprot_val(efimem_to_pgprot_map(md)) &
                                ~(_PAGE_GLOBAL));
        int i;

        /* RISC-V maps one page at a time */
        for (i = 0; i < md->num_pages; i++)
                create_pgd_mapping(mm->pgd, md->virt_addr + i * PAGE_SIZE,
                                   md->phys_addr + i * PAGE_SIZE,
                                   PAGE_SIZE, prot);
        return 0;
}

static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
{
        efi_memory_desc_t *md = data;
        pte_t pte = ptep_get(ptep);
        unsigned long val;

        if (md->attribute & EFI_MEMORY_RO) {
                val = pte_val(pte) & ~_PAGE_WRITE;
                val |= _PAGE_READ;
                pte = __pte(val);
        }
        if (md->attribute & EFI_MEMORY_XP) {
                val = pte_val(pte) & ~_PAGE_EXEC;
                pte = __pte(val);
        }
        set_pte(ptep, pte);

        return 0;
}

int __init efi_set_mapping_permissions(struct mm_struct *mm,
                                       efi_memory_desc_t *md,
                                       bool ignored)
{
        BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&
               md->type != EFI_RUNTIME_SERVICES_DATA);

        /*
         * Calling apply_to_page_range() is only safe on regions that are
         * guaranteed to be mapped down to pages. Since we are only called
         * for regions that have been mapped using efi_create_mapping() above
         * (and this is checked by the generic Memory Attributes table parsing
         * routines), there is no need to check that again here.
         */
        return apply_to_page_range(mm, md->virt_addr,
                                   md->num_pages << EFI_PAGE_SHIFT,
                                   set_permissions, md);
}