Commit 43b1df0e authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi/libstub: Add API function to allocate aligned memory 



Break out the code to create an aligned page allocation from mem.c
and move it into a function efi_allocate_pages_aligned() in alignedmem.c.
Update efi_allocate_pages() to invoke it unless the minimum alignment
equals the EFI page size (4 KB), in which case the ordinary page
allocator is sufficient. This way, efi_allocate_pages_aligned() will
only be pulled into the build if it is actually being used (which will
be on arm64 only in the immediate future)

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 5d12da9d

drivers/firmware/efi/libstub/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -42,7 +42,8 @@ KCOV_INSTRUMENT := n 


lib-y				:= efi-stub-helper.o gop.o secureboot.o tpm.o \

				   file.o mem.o random.o randomalloc.o pci.o \

				   skip_spaces.o lib-cmdline.o lib-ctype.o

				   skip_spaces.o lib-cmdline.o lib-ctype.o \

				   alignedmem.o



# include the stub's generic dependencies from lib/ when building for ARM/arm64

efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c

drivers/firmware/efi/libstub/alignedmem.c

0 → 100644
+57 −0
Original line number Diff line number Diff line 
// 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

 *

 * 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)

{

	efi_physical_addr_t alloc_addr;

	efi_status_t status;

	int slack;



	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,

			     EFI_LOADER_DATA, 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) / 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;

}

drivers/firmware/efi/libstub/efistub.h

+3 −0
Original line number Diff line number Diff line
@@ -657,6 +657,9 @@ efi_status_t efi_low_alloc(unsigned long size, unsigned long align, 
efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,

				unsigned long max);



efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,

					unsigned long max, unsigned long align);



efi_status_t efi_relocate_kernel(unsigned long *image_addr,

				 unsigned long image_size,

				 unsigned long alloc_size,

drivers/firmware/efi/libstub/mem.c

+9 −16
Original line number Diff line number Diff line
@@ -93,31 +93,24 @@ efi_status_t efi_get_memory_map(struct efi_boot_memmap *map) 
efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,

				unsigned long max)

{

	efi_physical_addr_t alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;

	int slack = EFI_ALLOC_ALIGN / EFI_PAGE_SIZE - 1;

	efi_physical_addr_t alloc_addr;

	efi_status_t status;



	size = round_up(size, EFI_ALLOC_ALIGN);

	if (EFI_ALLOC_ALIGN > EFI_PAGE_SIZE)

		return efi_allocate_pages_aligned(size, addr, max,

						  EFI_ALLOC_ALIGN);



	alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;

	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,

			     EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,

			     EFI_LOADER_DATA, DIV_ROUND_UP(size, EFI_PAGE_SIZE),

			     &alloc_addr);

	if (status != EFI_SUCCESS)

		return status;



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



	if (slack > 0) {

		int l = (alloc_addr % EFI_ALLOC_ALIGN) / 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);

	}

	*addr = alloc_addr;

	return EFI_SUCCESS;

}



/**

 * efi_low_alloc_above() - allocate pages at or above given address

 * @size:	size of the memory area to allocate