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efi/libstub: Add API function to allocate aligned memory

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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: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2020-03-27 16:09:40 +01:00
parent 5d12da9dd6
commit 43b1df0e01
4 changed files with 71 additions and 17 deletions
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3
drivers/firmware/efi/libstub/Makefile
View File

@ -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

57
drivers/firmware/efi/libstub/alignedmem.c Normal file
View File

@ -0,0 +1,57 @@
// 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;
}

3
drivers/firmware/efi/libstub/efistub.h
View File

@ -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,

25
drivers/firmware/efi/libstub/mem.c
View File

@ -93,31 +93,24 @@ fail:
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