// SPDX-License-Identifier: GPL-2.0

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

#include "efistub.h"

/**
 * efi_allocate_pages_aligned() - Allocate memory pages
 * @size:       minimum number of bytes to allocate
 * @addr:       On return the address of the first allocated page. The first
 *              allocated page has alignment EFI_ALLOC_ALIGN which is an
 *              architecture dependent multiple of the page size.
 * @max:        the address that the last allocated memory page shall not
 *              exceed
 * @align:      minimum alignment of the base of the allocation
 * @memory_type: the type of memory to allocate
 *
 * Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
 * to @align, which should be >= EFI_ALLOC_ALIGN. The last allocated page will
 * not exceed the address given by @max.
 *
 * Return:      status code
 */
efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
                                        unsigned long max, unsigned long align,
                                        int memory_type)
{
        efi_physical_addr_t alloc_addr;
        efi_status_t status;
        int slack;

        max = min(max, EFI_ALLOC_LIMIT);

        if (align < EFI_ALLOC_ALIGN)
                align = EFI_ALLOC_ALIGN;

        alloc_addr = ALIGN_DOWN(max + 1, align) - 1;
        size = round_up(size, EFI_ALLOC_ALIGN);
        slack = align / EFI_PAGE_SIZE - 1;

        status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
                             memory_type, size / EFI_PAGE_SIZE + slack,
                             &alloc_addr);
        if (status != EFI_SUCCESS)
                return status;

        *addr = ALIGN((unsigned long)alloc_addr, align);

        if (slack > 0) {
                int l = (alloc_addr & (align - 1)) / EFI_PAGE_SIZE;

                if (l) {
                        efi_bs_call(free_pages, alloc_addr, slack - l + 1);
                        slack = l - 1;
                }
                if (slack)
                        efi_bs_call(free_pages, *addr + size, slack);
        }
        return EFI_SUCCESS;
}