diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/relocate.c')
| -rw-r--r-- | drivers/firmware/efi/libstub/relocate.c | 165 |
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 000000000..bf6fbd5d2 --- /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; +} |