1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/efi.h> 4 #include <linux/pe.h> 5 #include <asm/efi.h> 6 #include <linux/unaligned.h> 7 8 #include "efistub.h" 9 10 static unsigned long alloc_preferred_address(unsigned long alloc_size) 11 { 12 #ifdef EFI_KIMG_PREFERRED_ADDRESS 13 efi_physical_addr_t efi_addr = EFI_KIMG_PREFERRED_ADDRESS; 14 15 if (efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA, 16 alloc_size / EFI_PAGE_SIZE, &efi_addr) == EFI_SUCCESS) 17 return efi_addr; 18 #endif 19 return ULONG_MAX; 20 } 21 22 void __weak efi_cache_sync_image(unsigned long image_base, 23 unsigned long alloc_size) 24 { 25 // Provided by the arch to perform the cache maintenance necessary for 26 // executable code loaded into memory to be safe for execution. 27 } 28 29 struct screen_info *alloc_screen_info(void) 30 { 31 return __alloc_screen_info(); 32 } 33 34 asmlinkage efi_status_t __efiapi 35 efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab) 36 { 37 char *cmdline_ptr __free(efi_pool) = NULL; 38 unsigned long image_base, alloc_size; 39 efi_loaded_image_t *image; 40 efi_status_t status; 41 42 WRITE_ONCE(efi_system_table, systab); 43 44 status = efi_bs_call(handle_protocol, handle, 45 &LOADED_IMAGE_PROTOCOL_GUID, (void **)&image); 46 if (status != EFI_SUCCESS) { 47 efi_err("Failed to locate parent's loaded image protocol\n"); 48 return status; 49 } 50 51 status = efi_handle_cmdline(image, &cmdline_ptr); 52 if (status != EFI_SUCCESS) 53 return status; 54 55 efi_info("Decompressing Linux Kernel...\n"); 56 57 status = efi_zboot_decompress_init(&alloc_size); 58 if (status != EFI_SUCCESS) 59 return status; 60 61 // If the architecture has a preferred address for the image, 62 // try that first. 63 image_base = alloc_preferred_address(alloc_size); 64 if (image_base == ULONG_MAX) { 65 unsigned long min_kimg_align = efi_get_kimg_min_align(); 66 u32 seed = U32_MAX; 67 68 if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 69 // Setting the random seed to 0x0 is the same as 70 // allocating as low as possible 71 seed = 0; 72 } else if (efi_nokaslr) { 73 efi_info("KASLR disabled on kernel command line\n"); 74 } else { 75 status = efi_get_random_bytes(sizeof(seed), (u8 *)&seed); 76 if (status == EFI_NOT_FOUND) { 77 efi_info("EFI_RNG_PROTOCOL unavailable\n"); 78 efi_nokaslr = true; 79 } else if (status != EFI_SUCCESS) { 80 efi_err("efi_get_random_bytes() failed (0x%lx)\n", 81 status); 82 efi_nokaslr = true; 83 } 84 } 85 86 status = efi_random_alloc(alloc_size, min_kimg_align, &image_base, 87 seed, EFI_LOADER_CODE, 0, EFI_ALLOC_LIMIT); 88 if (status != EFI_SUCCESS) { 89 efi_err("Failed to allocate memory\n"); 90 return status; 91 } 92 } 93 94 // Decompress the payload into the newly allocated buffer 95 status = efi_zboot_decompress((void *)image_base, alloc_size) ?: 96 efi_stub_common(handle, image, image_base, cmdline_ptr); 97 98 efi_free(alloc_size, image_base); 99 return status; 100 } 101