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
alloc_preferred_address(unsigned long alloc_size)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
efi_cache_sync_image(unsigned long image_base,unsigned long alloc_size)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
alloc_screen_info(void)29 struct screen_info *alloc_screen_info(void)
30 {
31 return __alloc_screen_info();
32 }
33
34 asmlinkage efi_status_t __efiapi
efi_zboot_entry(efi_handle_t handle,efi_system_table_t * systab)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