// SPDX-License-Identifier: GPL-2.0
/*
 * Common EFI memory map functions.
 */

#define pr_fmt(fmt) "efi: " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/efi.h>
#include <linux/io.h>
#include <asm/early_ioremap.h>
#include <linux/memblock.h>
#include <linux/slab.h>

static phys_addr_t __init __efi_memmap_alloc_early(unsigned long size)
{
        return memblock_phys_alloc(size, SMP_CACHE_BYTES);
}

static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
{
        unsigned int order = get_order(size);
        struct page *p = alloc_pages(GFP_KERNEL, order);

        if (!p)
                return 0;

        return PFN_PHYS(page_to_pfn(p));
}

/**
 * efi_memmap_alloc - Allocate memory for the EFI memory map
 * @num_entries: Number of entries in the allocated map.
 *
 * Depending on whether mm_init() has already been invoked or not,
 * either memblock or "normal" page allocation is used.
 *
 * Returns the physical address of the allocated memory map on
 * success, zero on failure.
 */
phys_addr_t __init efi_memmap_alloc(unsigned int num_entries)
{
        unsigned long size = num_entries * efi.memmap.desc_size;

        if (slab_is_available())
                return __efi_memmap_alloc_late(size);

        return __efi_memmap_alloc_early(size);
}

/**
 * __efi_memmap_init - Common code for mapping the EFI memory map
 * @data: EFI memory map data
 * @late: Use early or late mapping function?
 *
 * This function takes care of figuring out which function to use to
 * map the EFI memory map in efi.memmap based on how far into the boot
 * we are.
 *
 * During bootup @late should be %false since we only have access to
 * the early_memremap*() functions as the vmalloc space isn't setup.
 * Once the kernel is fully booted we can fallback to the more robust
 * memremap*() API.
 *
 * Returns zero on success, a negative error code on failure.
 */
static int __init
__efi_memmap_init(struct efi_memory_map_data *data, bool late)
{
        struct efi_memory_map map;
        phys_addr_t phys_map;

        if (efi_enabled(EFI_PARAVIRT))
                return 0;

        phys_map = data->phys_map;

        if (late)
                map.map = memremap(phys_map, data->size, MEMREMAP_WB);
        else
                map.map = early_memremap(phys_map, data->size);

        if (!map.map) {
                pr_err("Could not map the memory map!\n");
                return -ENOMEM;
        }

        map.phys_map = data->phys_map;
        map.nr_map = data->size / data->desc_size;
        map.map_end = map.map + data->size;

        map.desc_version = data->desc_version;
        map.desc_size = data->desc_size;
        map.late = late;

        set_bit(EFI_MEMMAP, &efi.flags);

        efi.memmap = map;

        return 0;
}

/**
 * efi_memmap_init_early - Map the EFI memory map data structure
 * @data: EFI memory map data
 *
 * Use early_memremap() to map the passed in EFI memory map and assign
 * it to efi.memmap.
 */
int __init efi_memmap_init_early(struct efi_memory_map_data *data)
{
        /* Cannot go backwards */
        WARN_ON(efi.memmap.late);

        return __efi_memmap_init(data, false);
}

void __init efi_memmap_unmap(void)
{
        if (!efi_enabled(EFI_MEMMAP))
                return;

        if (!efi.memmap.late) {
                unsigned long size;

                size = efi.memmap.desc_size * efi.memmap.nr_map;
                early_memunmap(efi.memmap.map, size);
        } else {
                memunmap(efi.memmap.map);
        }

        efi.memmap.map = NULL;
        clear_bit(EFI_MEMMAP, &efi.flags);
}

/**
 * efi_memmap_init_late - Map efi.memmap with memremap()
 * @phys_addr: Physical address of the new EFI memory map
 * @size: Size in bytes of the new EFI memory map
 *
 * Setup a mapping of the EFI memory map using ioremap_cache(). This
 * function should only be called once the vmalloc space has been
 * setup and is therefore not suitable for calling during early EFI
 * initialise, e.g. in efi_init(). Additionally, it expects
 * efi_memmap_init_early() to have already been called.
 *
 * The reason there are two EFI memmap initialisation
 * (efi_memmap_init_early() and this late version) is because the
 * early EFI memmap should be explicitly unmapped once EFI
 * initialisation is complete as the fixmap space used to map the EFI
 * memmap (via early_memremap()) is a scarce resource.
 *
 * This late mapping is intended to persist for the duration of
 * runtime so that things like efi_mem_desc_lookup() and
 * efi_mem_attributes() always work.
 *
 * Returns zero on success, a negative error code on failure.
 */
int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
{
        struct efi_memory_map_data data = {
                .phys_map = addr,
                .size = size,
        };

        /* Did we forget to unmap the early EFI memmap? */
        WARN_ON(efi.memmap.map);

        /* Were we already called? */
        WARN_ON(efi.memmap.late);

        /*
         * It makes no sense to allow callers to register different
         * values for the following fields. Copy them out of the
         * existing early EFI memmap.
         */
        data.desc_version = efi.memmap.desc_version;
        data.desc_size = efi.memmap.desc_size;

        return __efi_memmap_init(&data, true);
}

/**
 * efi_memmap_install - Install a new EFI memory map in efi.memmap
 * @addr: Physical address of the memory map
 * @nr_map: Number of entries in the memory map
 *
 * Unlike efi_memmap_init_*(), this function does not allow the caller
 * to switch from early to late mappings. It simply uses the existing
 * mapping function and installs the new memmap.
 *
 * Returns zero on success, a negative error code on failure.
 */
int __init efi_memmap_install(phys_addr_t addr, unsigned int nr_map)
{
        struct efi_memory_map_data data;

        efi_memmap_unmap();

        data.phys_map = addr;
        data.size = efi.memmap.desc_size * nr_map;
        data.desc_version = efi.memmap.desc_version;
        data.desc_size = efi.memmap.desc_size;

        return __efi_memmap_init(&data, efi.memmap.late);
}

/**
 * efi_memmap_split_count - Count number of additional EFI memmap entries
 * @md: EFI memory descriptor to split
 * @range: Address range (start, end) to split around
 *
 * Returns the number of additional EFI memmap entries required to
 * accomodate @range.
 */
int __init efi_memmap_split_count(efi_memory_desc_t *md, struct range *range)
{
        u64 m_start, m_end;
        u64 start, end;
        int count = 0;

        start = md->phys_addr;
        end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;

        /* modifying range */
        m_start = range->start;
        m_end = range->end;

        if (m_start <= start) {
                /* split into 2 parts */
                if (start < m_end && m_end < end)
                        count++;
        }

        if (start < m_start && m_start < end) {
                /* split into 3 parts */
                if (m_end < end)
                        count += 2;
                /* split into 2 parts */
                if (end <= m_end)
                        count++;
        }

        return count;
}

/**
 * efi_memmap_insert - Insert a memory region in an EFI memmap
 * @old_memmap: The existing EFI memory map structure
 * @buf: Address of buffer to store new map
 * @mem: Memory map entry to insert
 *
 * It is suggested that you call efi_memmap_split_count() first
 * to see how large @buf needs to be.
 */
void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
                              struct efi_mem_range *mem)
{
        u64 m_start, m_end, m_attr;
        efi_memory_desc_t *md;
        u64 start, end;
        void *old, *new;

        /* modifying range */
        m_start = mem->range.start;
        m_end = mem->range.end;
        m_attr = mem->attribute;

        /*
         * The EFI memory map deals with regions in EFI_PAGE_SIZE
         * units. Ensure that the region described by 'mem' is aligned
         * correctly.
         */
        if (!IS_ALIGNED(m_start, EFI_PAGE_SIZE) ||
            !IS_ALIGNED(m_end + 1, EFI_PAGE_SIZE)) {
                WARN_ON(1);
                return;
        }

        for (old = old_memmap->map, new = buf;
             old < old_memmap->map_end;
             old += old_memmap->desc_size, new += old_memmap->desc_size) {

                /* copy original EFI memory descriptor */
                memcpy(new, old, old_memmap->desc_size);
                md = new;
                start = md->phys_addr;
                end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;

                if (m_start <= start && end <= m_end)
                        md->attribute |= m_attr;

                if (m_start <= start &&
                    (start < m_end && m_end < end)) {
                        /* first part */
                        md->attribute |= m_attr;
                        md->num_pages = (m_end - md->phys_addr + 1) >>
                                EFI_PAGE_SHIFT;
                        /* latter part */
                        new += old_memmap->desc_size;
                        memcpy(new, old, old_memmap->desc_size);
                        md = new;
                        md->phys_addr = m_end + 1;
                        md->num_pages = (end - md->phys_addr + 1) >>
                                EFI_PAGE_SHIFT;
                }

                if ((start < m_start && m_start < end) && m_end < end) {
                        /* first part */
                        md->num_pages = (m_start - md->phys_addr) >>
                                EFI_PAGE_SHIFT;
                        /* middle part */
                        new += old_memmap->desc_size;
                        memcpy(new, old, old_memmap->desc_size);
                        md = new;
                        md->attribute |= m_attr;
                        md->phys_addr = m_start;
                        md->num_pages = (m_end - m_start + 1) >>
                                EFI_PAGE_SHIFT;
                        /* last part */
                        new += old_memmap->desc_size;
                        memcpy(new, old, old_memmap->desc_size);
                        md = new;
                        md->phys_addr = m_end + 1;
                        md->num_pages = (end - m_end) >>
                                EFI_PAGE_SHIFT;
                }

                if ((start < m_start && m_start < end) &&
                    (end <= m_end)) {
                        /* first part */
                        md->num_pages = (m_start - md->phys_addr) >>
                                EFI_PAGE_SHIFT;
                        /* latter part */
                        new += old_memmap->desc_size;
                        memcpy(new, old, old_memmap->desc_size);
                        md = new;
                        md->phys_addr = m_start;
                        md->num_pages = (end - md->phys_addr + 1) >>
                                EFI_PAGE_SHIFT;
                        md->attribute |= m_attr;
                }
        }
}