diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/arm64-stub.c')
| -rw-r--r-- | drivers/firmware/efi/libstub/arm64-stub.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c new file mode 100644 index 000000000..d4a6b12a8 --- /dev/null +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@linaro.org> + * + * This file implements the EFI boot stub for the arm64 kernel. + * Adapted from ARM version by Mark Salter <msalter@redhat.com> + */ + + +#include <linux/efi.h> +#include <asm/efi.h> +#include <asm/memory.h> +#include <asm/sections.h> + +#include "efistub.h" + +/* + * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail + * to provide space, and fail to zero it). Check for this condition by double + * checking that the first and the last byte of the image are covered by the + * same EFI memory map entry. + */ +static bool check_image_region(u64 base, u64 size) +{ + struct efi_boot_memmap *map; + efi_status_t status; + bool ret = false; + int map_offset; + + status = efi_get_memory_map(&map, false); + if (status != EFI_SUCCESS) + return false; + + for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) { + efi_memory_desc_t *md = (void *)map->map + map_offset; + u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; + + /* + * Find the region that covers base, and return whether + * it covers base+size bytes. + */ + if (base >= md->phys_addr && base < end) { + ret = (base + size) <= end; + break; + } + } + + efi_bs_call(free_pool, map); + + return ret; +} + +efi_status_t handle_kernel_image(unsigned long *image_addr, + unsigned long *image_size, + unsigned long *reserve_addr, + unsigned long *reserve_size, + efi_loaded_image_t *image, + efi_handle_t image_handle) +{ + efi_status_t status; + unsigned long kernel_size, kernel_codesize, kernel_memsize; + u32 phys_seed = 0; + u64 min_kimg_align = efi_get_kimg_min_align(); + + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { + efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID; + void *p; + + if (efi_nokaslr) { + efi_info("KASLR disabled on kernel command line\n"); + } else if (efi_bs_call(handle_protocol, image_handle, + &li_fixed_proto, &p) == EFI_SUCCESS) { + efi_info("Image placement fixed by loader\n"); + } else { + status = efi_get_random_bytes(sizeof(phys_seed), + (u8 *)&phys_seed); + if (status == EFI_NOT_FOUND) { + efi_info("EFI_RNG_PROTOCOL unavailable\n"); + efi_nokaslr = true; + } else if (status != EFI_SUCCESS) { + efi_err("efi_get_random_bytes() failed (0x%lx)\n", + status); + efi_nokaslr = true; + } + } + } + + if (image->image_base != _text) + efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); + + if (!IS_ALIGNED((u64)_text, SEGMENT_ALIGN)) + efi_err("FIRMWARE BUG: kernel image not aligned on %dk boundary\n", + SEGMENT_ALIGN >> 10); + + kernel_size = _edata - _text; + kernel_codesize = __inittext_end - _text; + kernel_memsize = kernel_size + (_end - _edata); + *reserve_size = kernel_memsize; + + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { + /* + * If KASLR is enabled, and we have some randomness available, + * locate the kernel at a randomized offset in physical memory. + */ + status = efi_random_alloc(*reserve_size, min_kimg_align, + reserve_addr, phys_seed, + EFI_LOADER_CODE); + if (status != EFI_SUCCESS) + efi_warn("efi_random_alloc() failed: 0x%lx\n", status); + } else { + status = EFI_OUT_OF_RESOURCES; + } + + if (status != EFI_SUCCESS) { + if (!check_image_region((u64)_text, kernel_memsize)) { + efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); + } else if (IS_ALIGNED((u64)_text, min_kimg_align) && + (u64)_end < EFI_ALLOC_LIMIT) { + /* + * Just execute from wherever we were loaded by the + * UEFI PE/COFF loader if the placement is suitable. + */ + *image_addr = (u64)_text; + *reserve_size = 0; + return EFI_SUCCESS; + } + + status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, + ULONG_MAX, min_kimg_align, + EFI_LOADER_CODE); + + if (status != EFI_SUCCESS) { + efi_err("Failed to relocate kernel\n"); + *reserve_size = 0; + return status; + } + } + + *image_addr = *reserve_addr; + memcpy((void *)*image_addr, _text, kernel_size); + caches_clean_inval_pou(*image_addr, *image_addr + kernel_codesize); + + return EFI_SUCCESS; +} + +asmlinkage void primary_entry(void); + +unsigned long primary_entry_offset(void) +{ + /* + * When built as part of the kernel, the EFI stub cannot branch to the + * kernel proper via the image header, as the PE/COFF header is + * strictly not part of the in-memory presentation of the image, only + * of the file representation. So instead, we need to jump to the + * actual entrypoint in the .text region of the image. + */ + return (char *)primary_entry - _text; +} |