1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * EFI_DT_FIXUP_PROTOCOL
4 *
5 * Copyright (c) 2020 Heinrich Schuchardt
6 */
7
8#include <efi_dt_fixup.h>
9#include <efi_loader.h>
10#include <efi_rng.h>
11#include <fdtdec.h>
12#include <mapmem.h>
13
14const efi_guid_t efi_guid_dt_fixup_protocol = EFI_DT_FIXUP_PROTOCOL_GUID;
15
16/**
17 * efi_reserve_memory() - add reserved memory to memory map
18 *
19 * @addr:	start address of the reserved memory range
20 * @size:	size of the reserved memory range
21 * @nomap:	indicates that the memory range shall not be accessed by the
22 *		UEFI payload
23 */
24static void efi_reserve_memory(u64 addr, u64 size, bool nomap)
25{
26	int type;
27	efi_uintn_t ret;
28
29	/* Convert from sandbox address space. */
30	addr = (uintptr_t)map_sysmem(addr, 0);
31
32	if (nomap)
33		type = EFI_RESERVED_MEMORY_TYPE;
34	else
35		type = EFI_BOOT_SERVICES_DATA;
36
37	ret = efi_add_memory_map(addr, size, type);
38	if (ret != EFI_SUCCESS)
39		log_err("Reserved memory mapping failed addr %llx size %llx\n",
40			addr, size);
41}
42
43/**
44 * efi_try_purge_kaslr_seed() - Remove unused kaslr-seed
45 *
46 * Kernel's EFI STUB only relies on EFI_RNG_PROTOCOL for randomization
47 * and completely ignores the kaslr-seed for its own randomness needs
48 * (i.e the randomization of the physical placement of the kernel).
49 * Weed it out from the DTB we hand over, which would mess up our DTB
50 * TPM measurements as well.
51 *
52 * @fdt: Pointer to device tree
53 */
54void efi_try_purge_kaslr_seed(void *fdt)
55{
56	const efi_guid_t efi_guid_rng_protocol = EFI_RNG_PROTOCOL_GUID;
57	struct efi_handler *handler;
58	efi_status_t ret;
59	int nodeoff = 0;
60	int err = 0;
61
62	ret = efi_search_protocol(efi_root, &efi_guid_rng_protocol, &handler);
63	if (ret != EFI_SUCCESS)
64		return;
65
66	nodeoff = fdt_path_offset(fdt, "/chosen");
67	if (nodeoff < 0)
68		return;
69
70	err = fdt_delprop(fdt, nodeoff, "kaslr-seed");
71	if (err < 0 && err != -FDT_ERR_NOTFOUND)
72		log_err("Error deleting kaslr-seed\n");
73}
74
75/**
76 * efi_carve_out_dt_rsv() - Carve out DT reserved memory ranges
77 *
78 * The mem_rsv entries of the FDT are added to the memory map. Any failures are
79 * ignored because this is not critical and we would rather continue to try to
80 * boot.
81 *
82 * @fdt: Pointer to device tree
83 */
84void efi_carve_out_dt_rsv(void *fdt)
85{
86	int nr_rsv, i;
87	u64 addr, size;
88	int nodeoffset, subnode;
89
90	nr_rsv = fdt_num_mem_rsv(fdt);
91
92	/* Look for an existing entry and add it to the efi mem map. */
93	for (i = 0; i < nr_rsv; i++) {
94		if (fdt_get_mem_rsv(fdt, i, &addr, &size) != 0)
95			continue;
96		efi_reserve_memory(addr, size, true);
97	}
98
99	/* process reserved-memory */
100	nodeoffset = fdt_subnode_offset(fdt, 0, "reserved-memory");
101	if (nodeoffset >= 0) {
102		subnode = fdt_first_subnode(fdt, nodeoffset);
103		while (subnode >= 0) {
104			fdt_addr_t fdt_addr;
105			fdt_size_t fdt_size;
106
107			/* check if this subnode has a reg property */
108			fdt_addr = fdtdec_get_addr_size_auto_parent(
109						fdt, nodeoffset, subnode,
110						"reg", 0, &fdt_size, false);
111			/*
112			 * The /reserved-memory node may have children with
113			 * a size instead of a reg property.
114			 */
115			if (fdt_addr != FDT_ADDR_T_NONE &&
116			    fdtdec_get_is_enabled(fdt, subnode)) {
117				bool nomap;
118
119				nomap = !!fdt_getprop(fdt, subnode, "no-map",
120						      NULL);
121				efi_reserve_memory(fdt_addr, fdt_size, nomap);
122			}
123			subnode = fdt_next_subnode(fdt, subnode);
124		}
125	}
126}
127
128/**
129 * efi_dt_fixup() - fix up device tree
130 *
131 * This function implements the Fixup() service of the
132 * EFI Device Tree Fixup Protocol.
133 *
134 * @this:		instance of the protocol
135 * @dtb:		device tree provided by caller
136 * @buffer_size:	size of buffer for the device tree including free space
137 * @flags:		bit field designating action to be performed
138 * Return:		status code
139 */
140static efi_status_t __maybe_unused EFIAPI
141efi_dt_fixup(struct efi_dt_fixup_protocol *this, void *dtb,
142	     efi_uintn_t *buffer_size, u32 flags)
143{
144	efi_status_t ret;
145	size_t required_size;
146	size_t total_size;
147	struct bootm_headers img = { 0 };
148
149	EFI_ENTRY("%p, %p, %p, %d", this, dtb, buffer_size, flags);
150
151	if (this != &efi_dt_fixup_prot || !dtb || !buffer_size ||
152	    !flags || (flags & ~EFI_DT_ALL)) {
153		ret = EFI_INVALID_PARAMETER;
154		goto out;
155	}
156	if (fdt_check_header(dtb)) {
157		ret = EFI_INVALID_PARAMETER;
158		goto out;
159	}
160	if (flags & EFI_DT_APPLY_FIXUPS) {
161		/* Check size */
162		required_size = fdt_off_dt_strings(dtb) +
163				fdt_size_dt_strings(dtb) +
164				0x3000;
165		total_size = fdt_totalsize(dtb);
166		if (required_size < total_size)
167			required_size = total_size;
168		if (required_size > *buffer_size) {
169			*buffer_size = required_size;
170			ret = EFI_BUFFER_TOO_SMALL;
171			goto out;
172		}
173
174		fdt_set_totalsize(dtb, *buffer_size);
175		if (image_setup_libfdt(&img, dtb, NULL)) {
176			log_err("failed to process device tree\n");
177			ret = EFI_INVALID_PARAMETER;
178			goto out;
179		}
180	}
181	if (flags & EFI_DT_RESERVE_MEMORY)
182		efi_carve_out_dt_rsv(dtb);
183
184	if (flags & EFI_DT_INSTALL_TABLE) {
185		ret = efi_install_configuration_table(&efi_guid_fdt, dtb);
186		if (ret != EFI_SUCCESS) {
187			log_err("failed to install device tree\n");
188			goto out;
189		}
190	}
191
192	ret = EFI_SUCCESS;
193out:
194	return EFI_EXIT(ret);
195}
196
197struct efi_dt_fixup_protocol efi_dt_fixup_prot = {
198	.revision = EFI_DT_FIXUP_PROTOCOL_REVISION,
199	.fixup = efi_dt_fixup
200};
201