// SPDX-License-Identifier: GPL-2.0

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

#include "efistub.h"

/**
 * efi_low_alloc_above() - allocate pages at or above given address
 * @size:       size of the memory area to allocate
 * @align:      minimum alignment of the allocated memory area. It should
 *              a power of two.
 * @addr:       on exit the address of the allocated memory
 * @min:        minimum address to used for the memory allocation
 *
 * Allocate at the lowest possible address that is not below @min as
 * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
 * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
 * given by @min.
 *
 * Return:      status code
 */
efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
                                 unsigned long *addr, unsigned long min)
{
        struct efi_boot_memmap *map __free(efi_pool) = NULL;
        efi_status_t status;
        unsigned long nr_pages;
        int i;

        status = efi_get_memory_map(&map, false);
        if (status != EFI_SUCCESS)
                return status;

        /*
         * Enforce minimum alignment that EFI or Linux requires when
         * requesting a specific address.  We are doing page-based (or
         * larger) allocations, and both the address and size must meet
         * alignment constraints.
         */
        if (align < EFI_ALLOC_ALIGN)
                align = EFI_ALLOC_ALIGN;

        size = round_up(size, EFI_ALLOC_ALIGN);
        nr_pages = size / EFI_PAGE_SIZE;
        for (i = 0; i < map->map_size / map->desc_size; i++) {
                efi_memory_desc_t *desc;
                unsigned long m = (unsigned long)map->map;
                u64 start, end;

                desc = efi_memdesc_ptr(m, map->desc_size, i);

                if (desc->type != EFI_CONVENTIONAL_MEMORY)
                        continue;

                if (desc->attribute & EFI_MEMORY_HOT_PLUGGABLE)
                        continue;

                if (efi_soft_reserve_enabled() &&
                    (desc->attribute & EFI_MEMORY_SP))
                        continue;

                if (desc->num_pages < nr_pages)
                        continue;

                start = desc->phys_addr;
                end = start + desc->num_pages * EFI_PAGE_SIZE;

                if (start < min)
                        start = min;

                start = round_up(start, align);
                if ((start + size) > end)
                        continue;

                status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
                                     EFI_LOADER_DATA, nr_pages, &start);
                if (status == EFI_SUCCESS) {
                        *addr = start;
                        break;
                }
        }

        if (i == map->map_size / map->desc_size)
                return EFI_NOT_FOUND;

        return EFI_SUCCESS;
}

/**
 * efi_relocate_kernel() - copy memory area
 * @image_addr:         pointer to address of memory area to copy
 * @image_size:         size of memory area to copy
 * @alloc_size:         minimum size of memory to allocate, must be greater or
 *                      equal to image_size
 * @preferred_addr:     preferred target address
 * @alignment:          minimum alignment of the allocated memory area. It
 *                      should be a power of two.
 * @min_addr:           minimum target address
 *
 * Copy a memory area to a newly allocated memory area aligned according
 * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
 * is not available, the allocated address will not be below @min_addr.
 * On exit, @image_addr is updated to the target copy address that was used.
 *
 * This function is used to copy the Linux kernel verbatim. It does not apply
 * any relocation changes.
 *
 * Return:              status code
 */
efi_status_t efi_relocate_kernel(unsigned long *image_addr,
                                 unsigned long image_size,
                                 unsigned long alloc_size,
                                 unsigned long preferred_addr,
                                 unsigned long alignment,
                                 unsigned long min_addr)
{
        unsigned long cur_image_addr;
        unsigned long new_addr = 0;
        efi_status_t status;
        unsigned long nr_pages;
        efi_physical_addr_t efi_addr = preferred_addr;

        if (!image_addr || !image_size || !alloc_size)
                return EFI_INVALID_PARAMETER;
        if (alloc_size < image_size)
                return EFI_INVALID_PARAMETER;

        cur_image_addr = *image_addr;

        /*
         * The EFI firmware loader could have placed the kernel image
         * anywhere in memory, but the kernel has restrictions on the
         * max physical address it can run at.  Some architectures
         * also have a preferred address, so first try to relocate
         * to the preferred address.  If that fails, allocate as low
         * as possible while respecting the required alignment.
         */
        nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
        status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
                             EFI_LOADER_DATA, nr_pages, &efi_addr);
        new_addr = efi_addr;
        /*
         * If preferred address allocation failed allocate as low as
         * possible.
         */
        if (status != EFI_SUCCESS) {
                status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
                                             min_addr);
        }
        if (status != EFI_SUCCESS) {
                efi_err("Failed to allocate usable memory for kernel.\n");
                return status;
        }

        /*
         * We know source/dest won't overlap since both memory ranges
         * have been allocated by UEFI, so we can safely use memcpy.
         */
        memcpy((void *)new_addr, (void *)cur_image_addr, image_size);

        /* Return the new address of the relocated image. */
        *image_addr = new_addr;

        return status;
}