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
 10static unsigned char zboot_heap[SZ_256K] __aligned(64);
 11static 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
 32extern char efi_zboot_header[];
 33extern char _gzdata_start[], _gzdata_end[];
 34
 35static void error(char *x)
 36{
 37	efi_err("EFI decompressor: %s\n", x);
 38}
 39
 40static 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
 52void __weak efi_cache_sync_image(unsigned long image_base,
 53				 unsigned long alloc_size)
 54{
 55	// Provided by the arch to perform the cache maintenance necessary for
 56	// executable code loaded into memory to be safe for execution.
 57}
 58
 59struct screen_info *alloc_screen_info(void)
 60{
 61	return __alloc_screen_info();
 62}
 63
 64asmlinkage efi_status_t __efiapi
 65efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab)
 66{
 67	unsigned long compressed_size = _gzdata_end - _gzdata_start;
 68	unsigned long image_base, alloc_size;
 69	efi_loaded_image_t *image;
 70	efi_status_t status;
 71	char *cmdline_ptr;
 72	int ret;
 73
 74	WRITE_ONCE(efi_system_table, systab);
 75
 76	free_mem_ptr = (unsigned long)&zboot_heap;
 77	free_mem_end_ptr = free_mem_ptr + sizeof(zboot_heap);
 78
 79	status = efi_bs_call(handle_protocol, handle,
 80			     &LOADED_IMAGE_PROTOCOL_GUID, (void **)&image);
 81	if (status != EFI_SUCCESS) {
 82		error("Failed to locate parent's loaded image protocol");
 83		return status;
 84	}
 85
 86	status = efi_handle_cmdline(image, &cmdline_ptr);
 87	if (status != EFI_SUCCESS)
 88		return status;
 89
 90	efi_info("Decompressing Linux Kernel...\n");
 91
 92	// SizeOfImage from the compressee's PE/COFF header
 93	alloc_size = round_up(get_unaligned_le32(_gzdata_end - 4),
 94			      EFI_ALLOC_ALIGN);
 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, 0, EFI_ALLOC_LIMIT);
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);
139
140	status = efi_stub_common(handle, image, image_base, cmdline_ptr);
141
142free_image:
143	efi_free(alloc_size, image_base);
144free_cmdline:
145	efi_bs_call(free_pool, cmdline_ptr);
146	return status;
147}