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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * dmi-sysfs.c
4 *
5 * This module exports the DMI tables read-only to userspace through the
6 * sysfs file system.
7 *
8 * Data is currently found below
9 * /sys/firmware/dmi/...
10 *
11 * DMI attributes are presented in attribute files with names
12 * formatted using %d-%d, so that the first integer indicates the
13 * structure type (0-255), and the second field is the instance of that
14 * entry.
15 *
16 * Copyright 2011 Google, Inc.
17 */
18
19#include <linux/kernel.h>
20#include <linux/init.h>
21#include <linux/module.h>
22#include <linux/types.h>
23#include <linux/kobject.h>
24#include <linux/dmi.h>
25#include <linux/capability.h>
26#include <linux/slab.h>
27#include <linux/list.h>
28#include <linux/io.h>
29#include <asm/dmi.h>
30
31#define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider
32 the top entry type is only 8 bits */
33
34struct dmi_sysfs_entry {
35 struct dmi_header dh;
36 struct kobject kobj;
37 int instance;
38 int position;
39 struct list_head list;
40 struct kobject *child;
41};
42
43/*
44 * Global list of dmi_sysfs_entry. Even though this should only be
45 * manipulated at setup and teardown, the lazy nature of the kobject
46 * system means we get lazy removes.
47 */
48static LIST_HEAD(entry_list);
49static DEFINE_SPINLOCK(entry_list_lock);
50
51/* dmi_sysfs_attribute - Top level attribute. used by all entries. */
52struct dmi_sysfs_attribute {
53 struct attribute attr;
54 ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf);
55};
56
57#define DMI_SYSFS_ATTR(_entry, _name) \
58struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \
59 .attr = {.name = __stringify(_name), .mode = 0400}, \
60 .show = dmi_sysfs_##_entry##_##_name, \
61}
62
63/*
64 * dmi_sysfs_mapped_attribute - Attribute where we require the entry be
65 * mapped in. Use in conjunction with dmi_sysfs_specialize_attr_ops.
66 */
67struct dmi_sysfs_mapped_attribute {
68 struct attribute attr;
69 ssize_t (*show)(struct dmi_sysfs_entry *entry,
70 const struct dmi_header *dh,
71 char *buf);
72};
73
74#define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \
75struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \
76 .attr = {.name = __stringify(_name), .mode = 0400}, \
77 .show = dmi_sysfs_##_entry##_##_name, \
78}
79
80/*************************************************
81 * Generic DMI entry support.
82 *************************************************/
83static void dmi_entry_free(struct kobject *kobj)
84{
85 kfree(kobj);
86}
87
88static struct dmi_sysfs_entry *to_entry(struct kobject *kobj)
89{
90 return container_of(kobj, struct dmi_sysfs_entry, kobj);
91}
92
93static struct dmi_sysfs_attribute *to_attr(struct attribute *attr)
94{
95 return container_of(attr, struct dmi_sysfs_attribute, attr);
96}
97
98static ssize_t dmi_sysfs_attr_show(struct kobject *kobj,
99 struct attribute *_attr, char *buf)
100{
101 struct dmi_sysfs_entry *entry = to_entry(kobj);
102 struct dmi_sysfs_attribute *attr = to_attr(_attr);
103
104 /* DMI stuff is only ever admin visible */
105 if (!capable(CAP_SYS_ADMIN))
106 return -EACCES;
107
108 return attr->show(entry, buf);
109}
110
111static const struct sysfs_ops dmi_sysfs_attr_ops = {
112 .show = dmi_sysfs_attr_show,
113};
114
115typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *,
116 const struct dmi_header *dh, void *);
117
118struct find_dmi_data {
119 struct dmi_sysfs_entry *entry;
120 dmi_callback callback;
121 void *private;
122 int instance_countdown;
123 ssize_t ret;
124};
125
126static void find_dmi_entry_helper(const struct dmi_header *dh,
127 void *_data)
128{
129 struct find_dmi_data *data = _data;
130 struct dmi_sysfs_entry *entry = data->entry;
131
132 /* Is this the entry we want? */
133 if (dh->type != entry->dh.type)
134 return;
135
136 if (data->instance_countdown != 0) {
137 /* try the next instance? */
138 data->instance_countdown--;
139 return;
140 }
141
142 /*
143 * Don't ever revisit the instance. Short circuit later
144 * instances by letting the instance_countdown run negative
145 */
146 data->instance_countdown--;
147
148 /* Found the entry */
149 data->ret = data->callback(entry, dh, data->private);
150}
151
152/* State for passing the read parameters through dmi_find_entry() */
153struct dmi_read_state {
154 char *buf;
155 loff_t pos;
156 size_t count;
157};
158
159static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry,
160 dmi_callback callback, void *private)
161{
162 struct find_dmi_data data = {
163 .entry = entry,
164 .callback = callback,
165 .private = private,
166 .instance_countdown = entry->instance,
167 .ret = -EIO, /* To signal the entry disappeared */
168 };
169 int ret;
170
171 ret = dmi_walk(find_dmi_entry_helper, &data);
172 /* This shouldn't happen, but just in case. */
173 if (ret)
174 return -EINVAL;
175 return data.ret;
176}
177
178/*
179 * Calculate and return the byte length of the dmi entry identified by
180 * dh. This includes both the formatted portion as well as the
181 * unformatted string space, including the two trailing nul characters.
182 */
183static size_t dmi_entry_length(const struct dmi_header *dh)
184{
185 const char *p = (const char *)dh;
186
187 p += dh->length;
188
189 while (p[0] || p[1])
190 p++;
191
192 return 2 + p - (const char *)dh;
193}
194
195/*************************************************
196 * Support bits for specialized DMI entry support
197 *************************************************/
198struct dmi_entry_attr_show_data {
199 struct attribute *attr;
200 char *buf;
201};
202
203static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
204 const struct dmi_header *dh,
205 void *_data)
206{
207 struct dmi_entry_attr_show_data *data = _data;
208 struct dmi_sysfs_mapped_attribute *attr;
209
210 attr = container_of(data->attr,
211 struct dmi_sysfs_mapped_attribute, attr);
212 return attr->show(entry, dh, data->buf);
213}
214
215static ssize_t dmi_entry_attr_show(struct kobject *kobj,
216 struct attribute *attr,
217 char *buf)
218{
219 struct dmi_entry_attr_show_data data = {
220 .attr = attr,
221 .buf = buf,
222 };
223 /* Find the entry according to our parent and call the
224 * normalized show method hanging off of the attribute */
225 return find_dmi_entry(to_entry(kobj->parent),
226 dmi_entry_attr_show_helper, &data);
227}
228
229static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
230 .show = dmi_entry_attr_show,
231};
232
233/*************************************************
234 * Specialized DMI entry support.
235 *************************************************/
236
237/*** Type 15 - System Event Table ***/
238
239#define DMI_SEL_ACCESS_METHOD_IO8 0x00
240#define DMI_SEL_ACCESS_METHOD_IO2x8 0x01
241#define DMI_SEL_ACCESS_METHOD_IO16 0x02
242#define DMI_SEL_ACCESS_METHOD_PHYS32 0x03
243#define DMI_SEL_ACCESS_METHOD_GPNV 0x04
244
245struct dmi_system_event_log {
246 struct dmi_header header;
247 u16 area_length;
248 u16 header_start_offset;
249 u16 data_start_offset;
250 u8 access_method;
251 u8 status;
252 u32 change_token;
253 union {
254 struct {
255 u16 index_addr;
256 u16 data_addr;
257 } io;
258 u32 phys_addr32;
259 u16 gpnv_handle;
260 u32 access_method_address;
261 };
262 u8 header_format;
263 u8 type_descriptors_supported_count;
264 u8 per_log_type_descriptor_length;
265 u8 supported_log_type_descriptos[];
266} __packed;
267
268#define DMI_SYSFS_SEL_FIELD(_field) \
269static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
270 const struct dmi_header *dh, \
271 char *buf) \
272{ \
273 struct dmi_system_event_log sel; \
274 if (sizeof(sel) > dmi_entry_length(dh)) \
275 return -EIO; \
276 memcpy(&sel, dh, sizeof(sel)); \
277 return sprintf(buf, "%u\n", sel._field); \
278} \
279static DMI_SYSFS_MAPPED_ATTR(sel, _field)
280
281DMI_SYSFS_SEL_FIELD(area_length);
282DMI_SYSFS_SEL_FIELD(header_start_offset);
283DMI_SYSFS_SEL_FIELD(data_start_offset);
284DMI_SYSFS_SEL_FIELD(access_method);
285DMI_SYSFS_SEL_FIELD(status);
286DMI_SYSFS_SEL_FIELD(change_token);
287DMI_SYSFS_SEL_FIELD(access_method_address);
288DMI_SYSFS_SEL_FIELD(header_format);
289DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
290DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
291
292static struct attribute *dmi_sysfs_sel_attrs[] = {
293 &dmi_sysfs_attr_sel_area_length.attr,
294 &dmi_sysfs_attr_sel_header_start_offset.attr,
295 &dmi_sysfs_attr_sel_data_start_offset.attr,
296 &dmi_sysfs_attr_sel_access_method.attr,
297 &dmi_sysfs_attr_sel_status.attr,
298 &dmi_sysfs_attr_sel_change_token.attr,
299 &dmi_sysfs_attr_sel_access_method_address.attr,
300 &dmi_sysfs_attr_sel_header_format.attr,
301 &dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
302 &dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
303 NULL,
304};
305ATTRIBUTE_GROUPS(dmi_sysfs_sel);
306
307static const struct kobj_type dmi_system_event_log_ktype = {
308 .release = dmi_entry_free,
309 .sysfs_ops = &dmi_sysfs_specialize_attr_ops,
310 .default_groups = dmi_sysfs_sel_groups,
311};
312
313#ifdef CONFIG_HAS_IOPORT
314typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
315 loff_t offset);
316
317static DEFINE_MUTEX(io_port_lock);
318
319static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
320 loff_t offset)
321{
322 u8 ret;
323
324 mutex_lock(&io_port_lock);
325 outb((u8)offset, sel->io.index_addr);
326 ret = inb(sel->io.data_addr);
327 mutex_unlock(&io_port_lock);
328 return ret;
329}
330
331static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
332 loff_t offset)
333{
334 u8 ret;
335
336 mutex_lock(&io_port_lock);
337 outb((u8)offset, sel->io.index_addr);
338 outb((u8)(offset >> 8), sel->io.index_addr + 1);
339 ret = inb(sel->io.data_addr);
340 mutex_unlock(&io_port_lock);
341 return ret;
342}
343
344static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
345 loff_t offset)
346{
347 u8 ret;
348
349 mutex_lock(&io_port_lock);
350 outw((u16)offset, sel->io.index_addr);
351 ret = inb(sel->io.data_addr);
352 mutex_unlock(&io_port_lock);
353 return ret;
354}
355
356static sel_io_reader sel_io_readers[] = {
357 [DMI_SEL_ACCESS_METHOD_IO8] = read_sel_8bit_indexed_io,
358 [DMI_SEL_ACCESS_METHOD_IO2x8] = read_sel_2x8bit_indexed_io,
359 [DMI_SEL_ACCESS_METHOD_IO16] = read_sel_16bit_indexed_io,
360};
361
362static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
363 const struct dmi_system_event_log *sel,
364 char *buf, loff_t pos, size_t count)
365{
366 ssize_t wrote = 0;
367
368 sel_io_reader io_reader = sel_io_readers[sel->access_method];
369
370 while (count && pos < sel->area_length) {
371 count--;
372 *(buf++) = io_reader(sel, pos++);
373 wrote++;
374 }
375
376 return wrote;
377}
378#endif
379
380static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
381 const struct dmi_system_event_log *sel,
382 char *buf, loff_t pos, size_t count)
383{
384 u8 __iomem *mapped;
385 ssize_t wrote = 0;
386
387 mapped = dmi_remap(sel->access_method_address, sel->area_length);
388 if (!mapped)
389 return -EIO;
390
391 while (count && pos < sel->area_length) {
392 count--;
393 *(buf++) = readb(mapped + pos++);
394 wrote++;
395 }
396
397 dmi_unmap(mapped);
398 return wrote;
399}
400
401static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
402 const struct dmi_header *dh,
403 void *_state)
404{
405 struct dmi_read_state *state = _state;
406 struct dmi_system_event_log sel;
407
408 if (sizeof(sel) > dmi_entry_length(dh))
409 return -EIO;
410
411 memcpy(&sel, dh, sizeof(sel));
412
413 switch (sel.access_method) {
414#ifdef CONFIG_HAS_IOPORT
415 case DMI_SEL_ACCESS_METHOD_IO8:
416 case DMI_SEL_ACCESS_METHOD_IO2x8:
417 case DMI_SEL_ACCESS_METHOD_IO16:
418 return dmi_sel_raw_read_io(entry, &sel, state->buf,
419 state->pos, state->count);
420#endif
421 case DMI_SEL_ACCESS_METHOD_PHYS32:
422 return dmi_sel_raw_read_phys32(entry, &sel, state->buf,
423 state->pos, state->count);
424 case DMI_SEL_ACCESS_METHOD_GPNV:
425 pr_info_ratelimited("dmi-sysfs: GPNV support missing.\n");
426 return -EIO;
427 default:
428 pr_info_ratelimited("dmi-sysfs: Unknown access method %02x\n",
429 sel.access_method);
430 return -EIO;
431 }
432}
433
434static ssize_t raw_event_log_read(struct file *filp, struct kobject *kobj,
435 const struct bin_attribute *bin_attr,
436 char *buf, loff_t pos, size_t count)
437{
438 struct dmi_sysfs_entry *entry = to_entry(kobj->parent);
439 struct dmi_read_state state = {
440 .buf = buf,
441 .pos = pos,
442 .count = count,
443 };
444
445 return find_dmi_entry(entry, dmi_sel_raw_read_helper, &state);
446}
447
448static const BIN_ATTR_ADMIN_RO(raw_event_log, 0);
449
450static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
451{
452 int ret;
453
454 entry->child = kzalloc_obj(*entry->child);
455 if (!entry->child)
456 return -ENOMEM;
457 ret = kobject_init_and_add(entry->child,
458 &dmi_system_event_log_ktype,
459 &entry->kobj,
460 "system_event_log");
461 if (ret)
462 goto out_free;
463
464 ret = sysfs_create_bin_file(entry->child, &bin_attr_raw_event_log);
465 if (ret)
466 goto out_del;
467
468 return 0;
469
470out_del:
471 kobject_del(entry->child);
472out_free:
473 kfree(entry->child);
474 return ret;
475}
476
477/*************************************************
478 * Generic DMI entry support.
479 *************************************************/
480
481static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf)
482{
483 return sprintf(buf, "%d\n", entry->dh.length);
484}
485
486static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf)
487{
488 return sprintf(buf, "%d\n", entry->dh.handle);
489}
490
491static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf)
492{
493 return sprintf(buf, "%d\n", entry->dh.type);
494}
495
496static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry,
497 char *buf)
498{
499 return sprintf(buf, "%d\n", entry->instance);
500}
501
502static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry,
503 char *buf)
504{
505 return sprintf(buf, "%d\n", entry->position);
506}
507
508static DMI_SYSFS_ATTR(entry, length);
509static DMI_SYSFS_ATTR(entry, handle);
510static DMI_SYSFS_ATTR(entry, type);
511static DMI_SYSFS_ATTR(entry, instance);
512static DMI_SYSFS_ATTR(entry, position);
513
514static struct attribute *dmi_sysfs_entry_attrs[] = {
515 &dmi_sysfs_attr_entry_length.attr,
516 &dmi_sysfs_attr_entry_handle.attr,
517 &dmi_sysfs_attr_entry_type.attr,
518 &dmi_sysfs_attr_entry_instance.attr,
519 &dmi_sysfs_attr_entry_position.attr,
520 NULL,
521};
522ATTRIBUTE_GROUPS(dmi_sysfs_entry);
523
524static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry,
525 const struct dmi_header *dh,
526 void *_state)
527{
528 struct dmi_read_state *state = _state;
529 size_t entry_length;
530
531 entry_length = dmi_entry_length(dh);
532
533 return memory_read_from_buffer(state->buf, state->count,
534 &state->pos, dh, entry_length);
535}
536
537static ssize_t raw_read(struct file *filp,
538 struct kobject *kobj,
539 const struct bin_attribute *bin_attr,
540 char *buf, loff_t pos, size_t count)
541{
542 struct dmi_sysfs_entry *entry = to_entry(kobj);
543 struct dmi_read_state state = {
544 .buf = buf,
545 .pos = pos,
546 .count = count,
547 };
548
549 return find_dmi_entry(entry, dmi_entry_raw_read_helper, &state);
550}
551
552static const BIN_ATTR_ADMIN_RO(raw, 0);
553
554static void dmi_sysfs_entry_release(struct kobject *kobj)
555{
556 struct dmi_sysfs_entry *entry = to_entry(kobj);
557
558 spin_lock(&entry_list_lock);
559 list_del(&entry->list);
560 spin_unlock(&entry_list_lock);
561 kfree(entry);
562}
563
564static const struct kobj_type dmi_sysfs_entry_ktype = {
565 .release = dmi_sysfs_entry_release,
566 .sysfs_ops = &dmi_sysfs_attr_ops,
567 .default_groups = dmi_sysfs_entry_groups,
568};
569
570static struct kset *dmi_kset;
571
572/* Global count of all instances seen. Only for setup */
573static int __initdata instance_counts[MAX_ENTRY_TYPE + 1];
574
575/* Global positional count of all entries seen. Only for setup */
576static int __initdata position_count;
577
578static void __init dmi_sysfs_register_handle(const struct dmi_header *dh,
579 void *_ret)
580{
581 struct dmi_sysfs_entry *entry;
582 int *ret = _ret;
583
584 /* If a previous entry saw an error, short circuit */
585 if (*ret)
586 return;
587
588 /* Allocate and register a new entry into the entries set */
589 entry = kzalloc_obj(*entry);
590 if (!entry) {
591 *ret = -ENOMEM;
592 return;
593 }
594
595 /* Set the key */
596 memcpy(&entry->dh, dh, sizeof(*dh));
597 entry->instance = instance_counts[dh->type]++;
598 entry->position = position_count++;
599
600 entry->kobj.kset = dmi_kset;
601 *ret = kobject_init_and_add(&entry->kobj, &dmi_sysfs_entry_ktype, NULL,
602 "%d-%d", dh->type, entry->instance);
603
604 /* Thread on the global list for cleanup */
605 spin_lock(&entry_list_lock);
606 list_add_tail(&entry->list, &entry_list);
607 spin_unlock(&entry_list_lock);
608
609 if (*ret) {
610 kobject_put(&entry->kobj);
611 return;
612 }
613
614 /* Handle specializations by type */
615 switch (dh->type) {
616 case DMI_ENTRY_SYSTEM_EVENT_LOG:
617 *ret = dmi_system_event_log(entry);
618 break;
619 default:
620 /* No specialization */
621 break;
622 }
623 if (*ret)
624 goto out_err;
625
626 /* Create the raw binary file to access the entry */
627 *ret = sysfs_create_bin_file(&entry->kobj, &bin_attr_raw);
628 if (*ret)
629 goto out_err;
630
631 return;
632out_err:
633 kobject_put(entry->child);
634 kobject_put(&entry->kobj);
635 return;
636}
637
638static void cleanup_entry_list(void)
639{
640 struct dmi_sysfs_entry *entry, *next;
641
642 /* No locks, we are on our way out */
643 list_for_each_entry_safe(entry, next, &entry_list, list) {
644 kobject_put(entry->child);
645 kobject_put(&entry->kobj);
646 }
647}
648
649static int __init dmi_sysfs_init(void)
650{
651 int error;
652 int val;
653
654 if (!dmi_kobj) {
655 pr_debug("dmi-sysfs: dmi entry is absent.\n");
656 error = -ENODATA;
657 goto err;
658 }
659
660 dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
661 if (!dmi_kset) {
662 error = -ENOMEM;
663 goto err;
664 }
665
666 val = 0;
667 error = dmi_walk(dmi_sysfs_register_handle, &val);
668 if (error)
669 goto err;
670 if (val) {
671 error = val;
672 goto err;
673 }
674
675 pr_debug("dmi-sysfs: loaded.\n");
676
677 return 0;
678err:
679 cleanup_entry_list();
680 kset_unregister(dmi_kset);
681 return error;
682}
683
684/* clean up everything. */
685static void __exit dmi_sysfs_exit(void)
686{
687 pr_debug("dmi-sysfs: unloading.\n");
688 cleanup_entry_list();
689 kset_unregister(dmi_kset);
690}
691
692module_init(dmi_sysfs_init);
693module_exit(dmi_sysfs_exit);
694
695MODULE_AUTHOR("Mike Waychison <[email protected]>");
696MODULE_DESCRIPTION("DMI sysfs support");
697MODULE_LICENSE("GPL");