summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/libstub/relocate.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/firmware/efi/libstub/relocate.c')
-rw-r--r--drivers/firmware/efi/libstub/relocate.c165
1 files changed, 165 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c
new file mode 100644
index 0000000000..bf6fbd5d22
--- /dev/null
+++ b/drivers/firmware/efi/libstub/relocate.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+/**
+ * efi_low_alloc_above() - allocate pages at or above given address
+ * @size: size of the memory area to allocate
+ * @align: minimum alignment of the allocated memory area. It should
+ * a power of two.
+ * @addr: on exit the address of the allocated memory
+ * @min: minimum address to used for the memory allocation
+ *
+ * Allocate at the lowest possible address that is not below @min as
+ * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
+ * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
+ * given by @min.
+ *
+ * Return: status code
+ */
+efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
+ unsigned long *addr, unsigned long min)
+{
+ struct efi_boot_memmap *map;
+ efi_status_t status;
+ unsigned long nr_pages;
+ int i;
+
+ status = efi_get_memory_map(&map, false);
+ if (status != EFI_SUCCESS)
+ goto fail;
+
+ /*
+ * Enforce minimum alignment that EFI or Linux requires when
+ * requesting a specific address. We are doing page-based (or
+ * larger) allocations, and both the address and size must meet
+ * alignment constraints.
+ */
+ if (align < EFI_ALLOC_ALIGN)
+ align = EFI_ALLOC_ALIGN;
+
+ size = round_up(size, EFI_ALLOC_ALIGN);
+ nr_pages = size / EFI_PAGE_SIZE;
+ for (i = 0; i < map->map_size / map->desc_size; i++) {
+ efi_memory_desc_t *desc;
+ unsigned long m = (unsigned long)map->map;
+ u64 start, end;
+
+ desc = efi_early_memdesc_ptr(m, map->desc_size, i);
+
+ if (desc->type != EFI_CONVENTIONAL_MEMORY)
+ continue;
+
+ if (efi_soft_reserve_enabled() &&
+ (desc->attribute & EFI_MEMORY_SP))
+ continue;
+
+ if (desc->num_pages < nr_pages)
+ continue;
+
+ start = desc->phys_addr;
+ end = start + desc->num_pages * EFI_PAGE_SIZE;
+
+ if (start < min)
+ start = min;
+
+ start = round_up(start, align);
+ if ((start + size) > end)
+ continue;
+
+ status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+ EFI_LOADER_DATA, nr_pages, &start);
+ if (status == EFI_SUCCESS) {
+ *addr = start;
+ break;
+ }
+ }
+
+ if (i == map->map_size / map->desc_size)
+ status = EFI_NOT_FOUND;
+
+ efi_bs_call(free_pool, map);
+fail:
+ return status;
+}
+
+/**
+ * efi_relocate_kernel() - copy memory area
+ * @image_addr: pointer to address of memory area to copy
+ * @image_size: size of memory area to copy
+ * @alloc_size: minimum size of memory to allocate, must be greater or
+ * equal to image_size
+ * @preferred_addr: preferred target address
+ * @alignment: minimum alignment of the allocated memory area. It
+ * should be a power of two.
+ * @min_addr: minimum target address
+ *
+ * Copy a memory area to a newly allocated memory area aligned according
+ * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
+ * is not available, the allocated address will not be below @min_addr.
+ * On exit, @image_addr is updated to the target copy address that was used.
+ *
+ * This function is used to copy the Linux kernel verbatim. It does not apply
+ * any relocation changes.
+ *
+ * Return: status code
+ */
+efi_status_t efi_relocate_kernel(unsigned long *image_addr,
+ unsigned long image_size,
+ unsigned long alloc_size,
+ unsigned long preferred_addr,
+ unsigned long alignment,
+ unsigned long min_addr)
+{
+ unsigned long cur_image_addr;
+ unsigned long new_addr = 0;
+ efi_status_t status;
+ unsigned long nr_pages;
+ efi_physical_addr_t efi_addr = preferred_addr;
+
+ if (!image_addr || !image_size || !alloc_size)
+ return EFI_INVALID_PARAMETER;
+ if (alloc_size < image_size)
+ return EFI_INVALID_PARAMETER;
+
+ cur_image_addr = *image_addr;
+
+ /*
+ * The EFI firmware loader could have placed the kernel image
+ * anywhere in memory, but the kernel has restrictions on the
+ * max physical address it can run at. Some architectures
+ * also have a preferred address, so first try to relocate
+ * to the preferred address. If that fails, allocate as low
+ * as possible while respecting the required alignment.
+ */
+ nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
+ status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+ EFI_LOADER_DATA, nr_pages, &efi_addr);
+ new_addr = efi_addr;
+ /*
+ * If preferred address allocation failed allocate as low as
+ * possible.
+ */
+ if (status != EFI_SUCCESS) {
+ status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
+ min_addr);
+ }
+ if (status != EFI_SUCCESS) {
+ efi_err("Failed to allocate usable memory for kernel.\n");
+ return status;
+ }
+
+ /*
+ * We know source/dest won't overlap since both memory ranges
+ * have been allocated by UEFI, so we can safely use memcpy.
+ */
+ memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
+
+ /* Return the new address of the relocated image. */
+ *image_addr = new_addr;
+
+ return status;
+}