1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/efi.h>
4 #include <asm/efi.h>
5 
6 #include "efistub.h"
7 
8 /**
9  * efi_allocate_pages_aligned() - Allocate memory pages
10  * @size:	minimum number of bytes to allocate
11  * @addr:	On return the address of the first allocated page. The first
12  *		allocated page has alignment EFI_ALLOC_ALIGN which is an
13  *		architecture dependent multiple of the page size.
14  * @max:	the address that the last allocated memory page shall not
15  *		exceed
16  * @align:	minimum alignment of the base of the allocation
17  *
18  * Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
19  * to @align, which should be >= EFI_ALLOC_ALIGN. The last allocated page will
20  * not exceed the address given by @max.
21  *
22  * Return:	status code
23  */
24 efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
25 					unsigned long max, unsigned long align)
26 {
27 	efi_physical_addr_t alloc_addr;
28 	efi_status_t status;
29 	int slack;
30 
31 	if (align < EFI_ALLOC_ALIGN)
32 		align = EFI_ALLOC_ALIGN;
33 
34 	alloc_addr = ALIGN_DOWN(max + 1, align) - 1;
35 	size = round_up(size, EFI_ALLOC_ALIGN);
36 	slack = align / EFI_PAGE_SIZE - 1;
37 
38 	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
39 			     EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,
40 			     &alloc_addr);
41 	if (status != EFI_SUCCESS)
42 		return status;
43 
44 	*addr = ALIGN((unsigned long)alloc_addr, align);
45 
46 	if (slack > 0) {
47 		int l = (alloc_addr & (align - 1)) / EFI_PAGE_SIZE;
48 
49 		if (l) {
50 			efi_bs_call(free_pages, alloc_addr, slack - l + 1);
51 			slack = l - 1;
52 		}
53 		if (slack)
54 			efi_bs_call(free_pages, *addr + size, slack);
55 	}
56 	return EFI_SUCCESS;
57 }
58