1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
4  *                platform or device firmware
5  *
6  *  Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
7  *  Copyright (C) 2023 Intel Corp.
8  */
9 #include <linux/errno.h>
10 #include <linux/acpi.h>
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/string.h>
14 #include <linux/types.h>
15 #include <linux/fw_table.h>
16 
17 enum acpi_subtable_type {
18 	ACPI_SUBTABLE_COMMON,
19 	ACPI_SUBTABLE_HMAT,
20 	ACPI_SUBTABLE_PRMT,
21 	ACPI_SUBTABLE_CEDT,
22 	CDAT_SUBTABLE,
23 };
24 
25 struct acpi_subtable_entry {
26 	union acpi_subtable_headers *hdr;
27 	enum acpi_subtable_type type;
28 };
29 
30 static unsigned long __init_or_fwtbl_lib
acpi_get_entry_type(struct acpi_subtable_entry * entry)31 acpi_get_entry_type(struct acpi_subtable_entry *entry)
32 {
33 	switch (entry->type) {
34 	case ACPI_SUBTABLE_COMMON:
35 		return entry->hdr->common.type;
36 	case ACPI_SUBTABLE_HMAT:
37 		return entry->hdr->hmat.type;
38 	case ACPI_SUBTABLE_PRMT:
39 		return 0;
40 	case ACPI_SUBTABLE_CEDT:
41 		return entry->hdr->cedt.type;
42 	case CDAT_SUBTABLE:
43 		return entry->hdr->cdat.type;
44 	}
45 	return 0;
46 }
47 
48 static unsigned long __init_or_fwtbl_lib
acpi_get_entry_length(struct acpi_subtable_entry * entry)49 acpi_get_entry_length(struct acpi_subtable_entry *entry)
50 {
51 	switch (entry->type) {
52 	case ACPI_SUBTABLE_COMMON:
53 		return entry->hdr->common.length;
54 	case ACPI_SUBTABLE_HMAT:
55 		return entry->hdr->hmat.length;
56 	case ACPI_SUBTABLE_PRMT:
57 		return entry->hdr->prmt.length;
58 	case ACPI_SUBTABLE_CEDT:
59 		return entry->hdr->cedt.length;
60 	case CDAT_SUBTABLE: {
61 		__le16 length = (__force __le16)entry->hdr->cdat.length;
62 
63 		return le16_to_cpu(length);
64 	}
65 	}
66 	return 0;
67 }
68 
69 static unsigned long __init_or_fwtbl_lib
acpi_get_subtable_header_length(struct acpi_subtable_entry * entry)70 acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
71 {
72 	switch (entry->type) {
73 	case ACPI_SUBTABLE_COMMON:
74 		return sizeof(entry->hdr->common);
75 	case ACPI_SUBTABLE_HMAT:
76 		return sizeof(entry->hdr->hmat);
77 	case ACPI_SUBTABLE_PRMT:
78 		return sizeof(entry->hdr->prmt);
79 	case ACPI_SUBTABLE_CEDT:
80 		return sizeof(entry->hdr->cedt);
81 	case CDAT_SUBTABLE:
82 		return sizeof(entry->hdr->cdat);
83 	}
84 	return 0;
85 }
86 
87 static enum acpi_subtable_type __init_or_fwtbl_lib
acpi_get_subtable_type(char * id)88 acpi_get_subtable_type(char *id)
89 {
90 	if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
91 		return ACPI_SUBTABLE_HMAT;
92 	if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
93 		return ACPI_SUBTABLE_PRMT;
94 	if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
95 		return ACPI_SUBTABLE_CEDT;
96 	if (strncmp(id, ACPI_SIG_CDAT, 4) == 0)
97 		return CDAT_SUBTABLE;
98 	return ACPI_SUBTABLE_COMMON;
99 }
100 
101 static unsigned long __init_or_fwtbl_lib
acpi_table_get_length(enum acpi_subtable_type type,union fw_table_header * header)102 acpi_table_get_length(enum acpi_subtable_type type,
103 		      union fw_table_header *header)
104 {
105 	if (type == CDAT_SUBTABLE) {
106 		__le32 length = (__force __le32)header->cdat.length;
107 
108 		return le32_to_cpu(length);
109 	}
110 
111 	return header->acpi.length;
112 }
113 
call_handler(struct acpi_subtable_proc * proc,union acpi_subtable_headers * hdr,unsigned long end)114 static __init_or_fwtbl_lib int call_handler(struct acpi_subtable_proc *proc,
115 					    union acpi_subtable_headers *hdr,
116 					    unsigned long end)
117 {
118 	if (proc->handler)
119 		return proc->handler(hdr, end);
120 	if (proc->handler_arg)
121 		return proc->handler_arg(hdr, proc->arg, end);
122 	return -EINVAL;
123 }
124 
125 /**
126  * acpi_parse_entries_array - for each proc_num find a suitable subtable
127  *
128  * @id: table id (for debugging purposes)
129  * @table_size: size of the root table
130  * @max_length: maximum size of the table (ignore if 0)
131  * @table_header: where does the table start?
132  * @proc: array of acpi_subtable_proc struct containing entry id
133  *        and associated handler with it
134  * @proc_num: how big proc is?
135  * @max_entries: how many entries can we process?
136  *
137  * For each proc_num find a subtable with proc->id and run proc->handler
138  * on it. Assumption is that there's only single handler for particular
139  * entry id.
140  *
141  * The table_size is not the size of the complete ACPI table (the length
142  * field in the header struct), but only the size of the root table; i.e.,
143  * the offset from the very first byte of the complete ACPI table, to the
144  * first byte of the very first subtable.
145  *
146  * On success returns sum of all matching entries for all proc handlers.
147  * Otherwise, -ENODEV or -EINVAL is returned.
148  */
149 int __init_or_fwtbl_lib
acpi_parse_entries_array(char * id,unsigned long table_size,union fw_table_header * table_header,unsigned long max_length,struct acpi_subtable_proc * proc,int proc_num,unsigned int max_entries)150 acpi_parse_entries_array(char *id, unsigned long table_size,
151 			 union fw_table_header *table_header,
152 			 unsigned long max_length,
153 			 struct acpi_subtable_proc *proc,
154 			 int proc_num, unsigned int max_entries)
155 {
156 	unsigned long table_len, table_end, subtable_len, entry_len;
157 	struct acpi_subtable_entry entry;
158 	enum acpi_subtable_type type;
159 	int count = 0;
160 	int i;
161 
162 	type = acpi_get_subtable_type(id);
163 	table_len = acpi_table_get_length(type, table_header);
164 	if (max_length && max_length < table_len)
165 		table_len = max_length;
166 	table_end = (unsigned long)table_header + table_len;
167 
168 	/* Parse all entries looking for a match. */
169 
170 	entry.type = type;
171 	entry.hdr = (union acpi_subtable_headers *)
172 	    ((unsigned long)table_header + table_size);
173 	subtable_len = acpi_get_subtable_header_length(&entry);
174 
175 	while (((unsigned long)entry.hdr) + subtable_len < table_end) {
176 		for (i = 0; i < proc_num; i++) {
177 			if (acpi_get_entry_type(&entry) != proc[i].id)
178 				continue;
179 
180 			if (!max_entries || count < max_entries)
181 				if (call_handler(&proc[i], entry.hdr, table_end))
182 					return -EINVAL;
183 
184 			proc[i].count++;
185 			count++;
186 			break;
187 		}
188 
189 		/*
190 		 * If entry->length is 0, break from this loop to avoid
191 		 * infinite loop.
192 		 */
193 		entry_len = acpi_get_entry_length(&entry);
194 		if (entry_len == 0) {
195 			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
196 			return -EINVAL;
197 		}
198 
199 		entry.hdr = (union acpi_subtable_headers *)
200 		    ((unsigned long)entry.hdr + entry_len);
201 	}
202 
203 	if (max_entries && count > max_entries) {
204 		pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
205 			id, proc->id, count - max_entries, count);
206 	}
207 
208 	return count;
209 }
210 
211 int __init_or_fwtbl_lib
cdat_table_parse(enum acpi_cdat_type type,acpi_tbl_entry_handler_arg handler_arg,void * arg,struct acpi_table_cdat * table_header,unsigned long length)212 cdat_table_parse(enum acpi_cdat_type type,
213 		 acpi_tbl_entry_handler_arg handler_arg,
214 		 void *arg,
215 		 struct acpi_table_cdat *table_header,
216 		 unsigned long length)
217 {
218 	struct acpi_subtable_proc proc = {
219 		.id		= type,
220 		.handler_arg	= handler_arg,
221 		.arg		= arg,
222 	};
223 
224 	if (!table_header)
225 		return -EINVAL;
226 
227 	return acpi_parse_entries_array(ACPI_SIG_CDAT,
228 					sizeof(struct acpi_table_cdat),
229 					(union fw_table_header *)table_header,
230 					length, &proc, 1, 0);
231 }
232 EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);
233