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 <asm/unaligned.h>
7 
8 #include "efistub.h"
9 
10 static unsigned char zboot_heap[SZ_256K] __aligned(64);
11 static unsigned long free_mem_ptr, free_mem_end_ptr;
12 
13 #define STATIC static
14 #if defined(CONFIG_KERNEL_GZIP)
15 #include "../../../../lib/decompress_inflate.c"
16 #elif defined(CONFIG_KERNEL_LZ4)
17 #include "../../../../lib/decompress_unlz4.c"
18 #elif defined(CONFIG_KERNEL_LZMA)
19 #include "../../../../lib/decompress_unlzma.c"
20 #elif defined(CONFIG_KERNEL_LZO)
21 #include "../../../../lib/decompress_unlzo.c"
22 #elif defined(CONFIG_KERNEL_XZ)
23 #undef memcpy
24 #define memcpy memcpy
25 #undef memmove
26 #define memmove memmove
27 #include "../../../../lib/decompress_unxz.c"
28 #elif defined(CONFIG_KERNEL_ZSTD)
29 #include "../../../../lib/decompress_unzstd.c"
30 #endif
31 
32 extern char efi_zboot_header[];
33 extern char _gzdata_start[], _gzdata_end[];
34 
35 static void error(char *x)
36 {
37 	efi_err("EFI decompressor: %s\n", x);
38 }
39 
40 static unsigned long alloc_preferred_address(unsigned long alloc_size)
41 {
42 #ifdef EFI_KIMG_PREFERRED_ADDRESS
43 	efi_physical_addr_t efi_addr = EFI_KIMG_PREFERRED_ADDRESS;
44 
45 	if (efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
46 			alloc_size / EFI_PAGE_SIZE, &efi_addr) == EFI_SUCCESS)
47 		return efi_addr;
48 #endif
49 	return ULONG_MAX;
50 }
51 
52 void __weak efi_cache_sync_image(unsigned long image_base,
53 				 unsigned long alloc_size,
54 				 unsigned long code_size)
55 {
56 	// Provided by the arch to perform the cache maintenance necessary for
57 	// executable code loaded into memory to be safe for execution.
58 }
59 
60 asmlinkage efi_status_t __efiapi
61 efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab)
62 {
63 	unsigned long compressed_size = _gzdata_end - _gzdata_start;
64 	unsigned long image_base, alloc_size, code_size;
65 	efi_loaded_image_t *image;
66 	efi_status_t status;
67 	char *cmdline_ptr;
68 	int ret;
69 
70 	WRITE_ONCE(efi_system_table, systab);
71 
72 	free_mem_ptr = (unsigned long)&zboot_heap;
73 	free_mem_end_ptr = free_mem_ptr + sizeof(zboot_heap);
74 
75 	status = efi_bs_call(handle_protocol, handle,
76 			     &LOADED_IMAGE_PROTOCOL_GUID, (void **)&image);
77 	if (status != EFI_SUCCESS) {
78 		error("Failed to locate parent's loaded image protocol");
79 		return status;
80 	}
81 
82 	status = efi_handle_cmdline(image, &cmdline_ptr);
83 	if (status != EFI_SUCCESS)
84 		return status;
85 
86 	efi_info("Decompressing Linux Kernel...\n");
87 
88 	// SizeOfImage from the compressee's PE/COFF header
89 	alloc_size = round_up(get_unaligned_le32(_gzdata_end - 4),
90 			      EFI_ALLOC_ALIGN);
91 
92 	// SizeOfHeaders and SizeOfCode from the compressee's PE/COFF header
93 	code_size = get_unaligned_le32(_gzdata_end - 8) +
94 		    get_unaligned_le32(_gzdata_end - 12);
95 
96 	 // If the architecture has a preferred address for the image,
97 	 // try that first.
98 	image_base = alloc_preferred_address(alloc_size);
99 	if (image_base == ULONG_MAX) {
100 		unsigned long min_kimg_align = efi_get_kimg_min_align();
101 		u32 seed = U32_MAX;
102 
103 		if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
104 			// Setting the random seed to 0x0 is the same as
105 			// allocating as low as possible
106 			seed = 0;
107 		} else if (efi_nokaslr) {
108 			efi_info("KASLR disabled on kernel command line\n");
109 		} else {
110 			status = efi_get_random_bytes(sizeof(seed), (u8 *)&seed);
111 			if (status == EFI_NOT_FOUND) {
112 				efi_info("EFI_RNG_PROTOCOL unavailable\n");
113 				efi_nokaslr = true;
114 			} else if (status != EFI_SUCCESS) {
115 				efi_err("efi_get_random_bytes() failed (0x%lx)\n",
116 					status);
117 				efi_nokaslr = true;
118 			}
119 		}
120 
121 		status = efi_random_alloc(alloc_size, min_kimg_align, &image_base,
122 					  seed, EFI_LOADER_CODE);
123 		if (status != EFI_SUCCESS) {
124 			efi_err("Failed to allocate memory\n");
125 			goto free_cmdline;
126 		}
127 	}
128 
129 	// Decompress the payload into the newly allocated buffer.
130 	ret = __decompress(_gzdata_start, compressed_size, NULL, NULL,
131 			   (void *)image_base, alloc_size, NULL, error);
132 	if (ret	< 0) {
133 		error("Decompression failed");
134 		status = EFI_DEVICE_ERROR;
135 		goto free_image;
136 	}
137 
138 	efi_cache_sync_image(image_base, alloc_size, code_size);
139 
140 	status = efi_stub_common(handle, image, image_base, cmdline_ptr);
141 
142 free_image:
143 	efi_free(alloc_size, image_base);
144 free_cmdline:
145 	efi_bs_call(free_pool, cmdline_ptr);
146 	return status;
147 }
148