// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org>
 */

#define pr_fmt(fmt)     "efi: memattr: " fmt

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

#include <asm/early_ioremap.h>

static int __initdata tbl_size;
unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR;

/*
 * Reserve the memory associated with the Memory Attributes configuration
 * table, if it exists.
 */
void __init efi_memattr_init(void)
{
        efi_memory_attributes_table_t *tbl;
        unsigned long size;

        if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR)
                return;

        tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl));
        if (!tbl) {
                pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
                       efi_mem_attr_table);
                return;
        }

        if (tbl->version > 2) {
                pr_warn("Unexpected EFI Memory Attributes table version %d\n",
                        tbl->version);
                goto unmap;
        }


        /*
         * Sanity check: the Memory Attributes Table contains up to 3 entries
         * for each entry of type EfiRuntimeServicesCode in the EFI memory map.
         * So if the size of the table exceeds 3x the size of the entire EFI
         * memory map, there is clearly something wrong, and the table should
         * just be ignored altogether.
         */
        size = tbl->num_entries * tbl->desc_size;
        if (size > 3 * efi.memmap.nr_map * efi.memmap.desc_size) {
                pr_warn(FW_BUG "Corrupted EFI Memory Attributes Table detected! (version == %u, desc_size == %u, num_entries == %u)\n",
                        tbl->version, tbl->desc_size, tbl->num_entries);
                goto unmap;
        }

        tbl_size = sizeof(*tbl) + size;
        memblock_reserve(efi_mem_attr_table, tbl_size);
        set_bit(EFI_MEM_ATTR, &efi.flags);

unmap:
        early_memunmap(tbl, sizeof(*tbl));
}

/*
 * Returns a copy @out of the UEFI memory descriptor @in if it is covered
 * entirely by a UEFI memory map entry with matching attributes. The virtual
 * address of @out is set according to the matching entry that was found.
 */
static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out)
{
        u64 in_paddr = in->phys_addr;
        u64 in_size = in->num_pages << EFI_PAGE_SHIFT;
        efi_memory_desc_t *md;

        *out = *in;

        if (in->type != EFI_RUNTIME_SERVICES_CODE &&
            in->type != EFI_RUNTIME_SERVICES_DATA) {
                pr_warn("Entry type should be RuntimeServiceCode/Data\n");
                return false;
        }

        if (PAGE_SIZE > EFI_PAGE_SIZE &&
            (!PAGE_ALIGNED(in->phys_addr) ||
             !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {
                /*
                 * Since arm64 may execute with page sizes of up to 64 KB, the
                 * UEFI spec mandates that RuntimeServices memory regions must
                 * be 64 KB aligned. We need to validate this here since we will
                 * not be able to tighten permissions on such regions without
                 * affecting adjacent regions.
                 */
                pr_warn("Entry address region misaligned\n");
                return false;
        }

        for_each_efi_memory_desc(md) {
                u64 md_paddr = md->phys_addr;
                u64 md_size = md->num_pages << EFI_PAGE_SHIFT;

                if (!(md->attribute & EFI_MEMORY_RUNTIME))
                        continue;
                if (md->virt_addr == 0 && md->phys_addr != 0) {
                        /* no virtual mapping has been installed by the stub */
                        break;
                }

                if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size)
                        continue;

                /*
                 * This entry covers the start of @in, check whether
                 * it covers the end as well.
                 */
                if (md_paddr + md_size < in_paddr + in_size) {
                        pr_warn("Entry covers multiple EFI memory map regions\n");
                        return false;
                }

                if (md->type != in->type) {
                        pr_warn("Entry type deviates from EFI memory map region type\n");
                        return false;
                }

                out->virt_addr = in_paddr + (md->virt_addr - md_paddr);

                return true;
        }

        pr_warn("No matching entry found in the EFI memory map\n");
        return false;
}

/*
 * To be called after the EFI page tables have been populated. If a memory
 * attributes table is available, its contents will be used to update the
 * mappings with tightened permissions as described by the table.
 * This requires the UEFI memory map to have already been populated with
 * virtual addresses.
 */
int __init efi_memattr_apply_permissions(struct mm_struct *mm,
                                         efi_memattr_perm_setter fn)
{
        efi_memory_attributes_table_t *tbl;
        bool has_bti = false;
        int i, ret;

        if (tbl_size <= sizeof(*tbl))
                return 0;

        /*
         * We need the EFI memory map to be setup so we can use it to
         * lookup the virtual addresses of all entries in the  of EFI
         * Memory Attributes table. If it isn't available, this
         * function should not be called.
         */
        if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
                return 0;

        tbl = memremap(efi_mem_attr_table, tbl_size, MEMREMAP_WB);
        if (!tbl) {
                pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
                       efi_mem_attr_table);
                return -ENOMEM;
        }

        if (tbl->version > 1 &&
            (tbl->flags & EFI_MEMORY_ATTRIBUTES_FLAGS_RT_FORWARD_CONTROL_FLOW_GUARD))
                has_bti = true;

        if (efi_enabled(EFI_DBG))
                pr_info("Processing EFI Memory Attributes table:\n");

        for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {
                efi_memory_desc_t md;
                unsigned long size;
                bool valid;
                char buf[64];

                valid = entry_is_valid(efi_memdesc_ptr(tbl->entry, tbl->desc_size, i),
                                       &md);
                size = md.num_pages << EFI_PAGE_SHIFT;
                if (efi_enabled(EFI_DBG) || !valid)
                        pr_info("%s 0x%012llx-0x%012llx %s\n",
                                valid ? "" : "!", md.phys_addr,
                                md.phys_addr + size - 1,
                                efi_md_typeattr_format(buf, sizeof(buf), &md));

                if (valid) {
                        ret = fn(mm, &md, has_bti);
                        if (ret)
                                pr_err("Error updating mappings, skipping subsequent md's\n");
                }
        }
        memunmap(tbl);
        return ret;
}