[PATCH 23/33] efi/libstub: Add API function to allocate aligned memory

Ard Biesheuvel
2020-04-24T13:07:54Z

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>
---
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/alignedmem.c | 57 +++++++++++++++++++++++
drivers/firmware/efi/libstub/efistub.h | 3 ++
drivers/firmware/efi/libstub/mem.c | 25 ++++------
4 files changed, 71 insertions(+), 17 deletions(-)
create mode 100644 drivers/firmware/efi/libstub/alignedmem.c

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 75cb2c3a1519..bb8af2b16c49 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -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
diff --git a/drivers/firmware/efi/libstub/alignedmem.c b/drivers/firmware/efi/libstub/alignedmem.c
new file mode 100644
index 000000000000..cc89c4d6196f
--- /dev/null
+++ b/drivers/firmware/efi/libstub/alignedmem.c
@@ -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;
+}
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 9af65be3b278..baa0bc166074 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -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,
diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
index 869a79c8946f..0020b0fa9587 100644
--- a/drivers/firmware/efi/libstub/mem.c
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -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
--
2.17.1