1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PowerNV OPAL Dump Interface
4 *
5 * Copyright 2013,2014 IBM Corp.
6 */
7
8#include <linux/kobject.h>
9#include <linux/mm.h>
10#include <linux/slab.h>
11#include <linux/vmalloc.h>
12#include <linux/pagemap.h>
13#include <linux/delay.h>
14#include <linux/interrupt.h>
15
16#include <asm/opal.h>
17
18#define DUMP_TYPE_FSP	0x01
19
20struct dump_obj {
21	struct kobject  kobj;
22	struct bin_attribute dump_attr;
23	uint32_t	id;  /* becomes object name */
24	uint32_t	type;
25	uint32_t	size;
26	char		*buffer;
27};
28#define to_dump_obj(x) container_of(x, struct dump_obj, kobj)
29
30struct dump_attribute {
31	struct attribute attr;
32	ssize_t (*show)(struct dump_obj *dump, struct dump_attribute *attr,
33			char *buf);
34	ssize_t (*store)(struct dump_obj *dump, struct dump_attribute *attr,
35			 const char *buf, size_t count);
36};
37#define to_dump_attr(x) container_of(x, struct dump_attribute, attr)
38
39static ssize_t dump_id_show(struct dump_obj *dump_obj,
40			    struct dump_attribute *attr,
41			    char *buf)
42{
43	return sprintf(buf, "0x%x\n", dump_obj->id);
44}
45
46static const char* dump_type_to_string(uint32_t type)
47{
48	switch (type) {
49	case 0x01: return "SP Dump";
50	case 0x02: return "System/Platform Dump";
51	case 0x03: return "SMA Dump";
52	default: return "unknown";
53	}
54}
55
56static ssize_t dump_type_show(struct dump_obj *dump_obj,
57			      struct dump_attribute *attr,
58			      char *buf)
59{
60
61	return sprintf(buf, "0x%x %s\n", dump_obj->type,
62		       dump_type_to_string(dump_obj->type));
63}
64
65static ssize_t dump_ack_show(struct dump_obj *dump_obj,
66			     struct dump_attribute *attr,
67			     char *buf)
68{
69	return sprintf(buf, "ack - acknowledge dump\n");
70}
71
72/*
73 * Send acknowledgement to OPAL
74 */
75static int64_t dump_send_ack(uint32_t dump_id)
76{
77	int rc;
78
79	rc = opal_dump_ack(dump_id);
80	if (rc)
81		pr_warn("%s: Failed to send ack to Dump ID 0x%x (%d)\n",
82			__func__, dump_id, rc);
83	return rc;
84}
85
86static ssize_t dump_ack_store(struct dump_obj *dump_obj,
87			      struct dump_attribute *attr,
88			      const char *buf,
89			      size_t count)
90{
91	/*
92	 * Try to self remove this attribute. If we are successful,
93	 * delete the kobject itself.
94	 */
95	if (sysfs_remove_file_self(&dump_obj->kobj, &attr->attr)) {
96		dump_send_ack(dump_obj->id);
97		kobject_put(&dump_obj->kobj);
98	}
99	return count;
100}
101
102/* Attributes of a dump
103 * The binary attribute of the dump itself is dynamic
104 * due to the dynamic size of the dump
105 */
106static struct dump_attribute id_attribute =
107	__ATTR(id, 0444, dump_id_show, NULL);
108static struct dump_attribute type_attribute =
109	__ATTR(type, 0444, dump_type_show, NULL);
110static struct dump_attribute ack_attribute =
111	__ATTR(acknowledge, 0660, dump_ack_show, dump_ack_store);
112
113static ssize_t init_dump_show(struct dump_obj *dump_obj,
114			      struct dump_attribute *attr,
115			      char *buf)
116{
117	return sprintf(buf, "1 - initiate Service Processor(FSP) dump\n");
118}
119
120static int64_t dump_fips_init(uint8_t type)
121{
122	int rc;
123
124	rc = opal_dump_init(type);
125	if (rc)
126		pr_warn("%s: Failed to initiate FSP dump (%d)\n",
127			__func__, rc);
128	return rc;
129}
130
131static ssize_t init_dump_store(struct dump_obj *dump_obj,
132			       struct dump_attribute *attr,
133			       const char *buf,
134			       size_t count)
135{
136	int rc;
137
138	rc = dump_fips_init(DUMP_TYPE_FSP);
139	if (rc == OPAL_SUCCESS)
140		pr_info("%s: Initiated FSP dump\n", __func__);
141
142	return count;
143}
144
145static struct dump_attribute initiate_attribute =
146	__ATTR(initiate_dump, 0600, init_dump_show, init_dump_store);
147
148static struct attribute *initiate_attrs[] = {
149	&initiate_attribute.attr,
150	NULL,
151};
152
153static struct attribute_group initiate_attr_group = {
154	.attrs = initiate_attrs,
155};
156
157static struct kset *dump_kset;
158
159static ssize_t dump_attr_show(struct kobject *kobj,
160			      struct attribute *attr,
161			      char *buf)
162{
163	struct dump_attribute *attribute;
164	struct dump_obj *dump;
165
166	attribute = to_dump_attr(attr);
167	dump = to_dump_obj(kobj);
168
169	if (!attribute->show)
170		return -EIO;
171
172	return attribute->show(dump, attribute, buf);
173}
174
175static ssize_t dump_attr_store(struct kobject *kobj,
176			       struct attribute *attr,
177			       const char *buf, size_t len)
178{
179	struct dump_attribute *attribute;
180	struct dump_obj *dump;
181
182	attribute = to_dump_attr(attr);
183	dump = to_dump_obj(kobj);
184
185	if (!attribute->store)
186		return -EIO;
187
188	return attribute->store(dump, attribute, buf, len);
189}
190
191static const struct sysfs_ops dump_sysfs_ops = {
192	.show = dump_attr_show,
193	.store = dump_attr_store,
194};
195
196static void dump_release(struct kobject *kobj)
197{
198	struct dump_obj *dump;
199
200	dump = to_dump_obj(kobj);
201	vfree(dump->buffer);
202	kfree(dump);
203}
204
205static struct attribute *dump_default_attrs[] = {
206	&id_attribute.attr,
207	&type_attribute.attr,
208	&ack_attribute.attr,
209	NULL,
210};
211
212static struct kobj_type dump_ktype = {
213	.sysfs_ops = &dump_sysfs_ops,
214	.release = &dump_release,
215	.default_attrs = dump_default_attrs,
216};
217
218static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
219{
220	__be32 id, size, type;
221	int rc;
222
223	type = cpu_to_be32(0xffffffff);
224
225	rc = opal_dump_info2(&id, &size, &type);
226	if (rc == OPAL_PARAMETER)
227		rc = opal_dump_info(&id, &size);
228
229	if (rc) {
230		pr_warn("%s: Failed to get dump info (%d)\n",
231			__func__, rc);
232		return rc;
233	}
234
235	*dump_id = be32_to_cpu(id);
236	*dump_size = be32_to_cpu(size);
237	*dump_type = be32_to_cpu(type);
238
239	return rc;
240}
241
242static int64_t dump_read_data(struct dump_obj *dump)
243{
244	struct opal_sg_list *list;
245	uint64_t addr;
246	int64_t rc;
247
248	/* Allocate memory */
249	dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
250	if (!dump->buffer) {
251		pr_err("%s : Failed to allocate memory\n", __func__);
252		rc = -ENOMEM;
253		goto out;
254	}
255
256	/* Generate SG list */
257	list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
258	if (!list) {
259		rc = -ENOMEM;
260		goto out;
261	}
262
263	/* First entry address */
264	addr = __pa(list);
265
266	/* Fetch data */
267	rc = OPAL_BUSY_EVENT;
268	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
269		rc = opal_dump_read(dump->id, addr);
270		if (rc == OPAL_BUSY_EVENT) {
271			opal_poll_events(NULL);
272			msleep(20);
273		}
274	}
275
276	if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
277		pr_warn("%s: Extract dump failed for ID 0x%x\n",
278			__func__, dump->id);
279
280	/* Free SG list */
281	opal_free_sg_list(list);
282
283out:
284	return rc;
285}
286
287static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
288			      struct bin_attribute *bin_attr,
289			      char *buffer, loff_t pos, size_t count)
290{
291	ssize_t rc;
292
293	struct dump_obj *dump = to_dump_obj(kobj);
294
295	if (!dump->buffer) {
296		rc = dump_read_data(dump);
297
298		if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
299			vfree(dump->buffer);
300			dump->buffer = NULL;
301
302			return -EIO;
303		}
304		if (rc == OPAL_PARTIAL) {
305			/* On a partial read, we just return EIO
306			 * and rely on userspace to ask us to try
307			 * again.
308			 */
309			pr_info("%s: Platform dump partially read. ID = 0x%x\n",
310				__func__, dump->id);
311			return -EIO;
312		}
313	}
314
315	memcpy(buffer, dump->buffer + pos, count);
316
317	/* You may think we could free the dump buffer now and retrieve
318	 * it again later if needed, but due to current firmware limitation,
319	 * that's not the case. So, once read into userspace once,
320	 * we keep the dump around until it's acknowledged by userspace.
321	 */
322
323	return count;
324}
325
326static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
327{
328	struct dump_obj *dump;
329	int rc;
330
331	dump = kzalloc(sizeof(*dump), GFP_KERNEL);
332	if (!dump)
333		return;
334
335	dump->kobj.kset = dump_kset;
336
337	kobject_init(&dump->kobj, &dump_ktype);
338
339	sysfs_bin_attr_init(&dump->dump_attr);
340
341	dump->dump_attr.attr.name = "dump";
342	dump->dump_attr.attr.mode = 0400;
343	dump->dump_attr.size = size;
344	dump->dump_attr.read = dump_attr_read;
345
346	dump->id = id;
347	dump->size = size;
348	dump->type = type;
349
350	rc = kobject_add(&dump->kobj, NULL, "0x%x-0x%x", type, id);
351	if (rc) {
352		kobject_put(&dump->kobj);
353		return;
354	}
355
356	/*
357	 * As soon as the sysfs file for this dump is created/activated there is
358	 * a chance the opal_errd daemon (or any userspace) might read and
359	 * acknowledge the dump before kobject_uevent() is called. If that
360	 * happens then there is a potential race between
361	 * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
362	 * use-after-free of a kernfs object resulting in a kernel crash.
363	 *
364	 * To avoid that, we need to take a reference on behalf of the bin file,
365	 * so that our reference remains valid while we call kobject_uevent().
366	 * We then drop our reference before exiting the function, leaving the
367	 * bin file to drop the last reference (if it hasn't already).
368	 */
369
370	/* Take a reference for the bin file */
371	kobject_get(&dump->kobj);
372	rc = sysfs_create_bin_file(&dump->kobj, &dump->dump_attr);
373	if (rc == 0) {
374		kobject_uevent(&dump->kobj, KOBJ_ADD);
375
376		pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
377			__func__, dump->id, dump->size);
378	} else {
379		/* Drop reference count taken for bin file */
380		kobject_put(&dump->kobj);
381	}
382
383	/* Drop our reference */
384	kobject_put(&dump->kobj);
385	return;
386}
387
388static irqreturn_t process_dump(int irq, void *data)
389{
390	int rc;
391	uint32_t dump_id, dump_size, dump_type;
392	char name[22];
393	struct kobject *kobj;
394
395	rc = dump_read_info(&dump_id, &dump_size, &dump_type);
396	if (rc != OPAL_SUCCESS)
397		return IRQ_HANDLED;
398
399	sprintf(name, "0x%x-0x%x", dump_type, dump_id);
400
401	/* we may get notified twice, let's handle
402	 * that gracefully and not create two conflicting
403	 * entries.
404	 */
405	kobj = kset_find_obj(dump_kset, name);
406	if (kobj) {
407		/* Drop reference added by kset_find_obj() */
408		kobject_put(kobj);
409		return IRQ_HANDLED;
410	}
411
412	create_dump_obj(dump_id, dump_size, dump_type);
413
414	return IRQ_HANDLED;
415}
416
417void __init opal_platform_dump_init(void)
418{
419	int rc;
420	int dump_irq;
421
422	/* ELOG not supported by firmware */
423	if (!opal_check_token(OPAL_DUMP_READ))
424		return;
425
426	dump_kset = kset_create_and_add("dump", NULL, opal_kobj);
427	if (!dump_kset) {
428		pr_warn("%s: Failed to create dump kset\n", __func__);
429		return;
430	}
431
432	rc = sysfs_create_group(&dump_kset->kobj, &initiate_attr_group);
433	if (rc) {
434		pr_warn("%s: Failed to create initiate dump attr group\n",
435			__func__);
436		kobject_put(&dump_kset->kobj);
437		return;
438	}
439
440	dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
441	if (!dump_irq) {
442		pr_err("%s: Can't register OPAL event irq (%d)\n",
443		       __func__, dump_irq);
444		return;
445	}
446
447	rc = request_threaded_irq(dump_irq, NULL, process_dump,
448				IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
449				"opal-dump", NULL);
450	if (rc) {
451		pr_err("%s: Can't request OPAL event irq (%d)\n",
452		       __func__, rc);
453		return;
454	}
455
456	if (opal_check_token(OPAL_DUMP_RESEND))
457		opal_dump_resend_notification();
458}
459