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, fmt: "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, fmt: "0x%x %s\n", dump_obj->type,
62 dump_type_to_string(type: 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, fmt: "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(kobj: &dump_obj->kobj, attr: &attr->attr)) {
96 dump_send_ack(dump_id: dump_obj->id);
97 kobject_put(kobj: &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, fmt: "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 const 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(addr: dump->buffer);
202 kfree(objp: dump);
203}
204
205static struct attribute *dump_default_attrs[] = {
206 &id_attribute.attr,
207 &type_attribute.attr,
208 &ack_attribute.attr,
209 NULL,
210};
211ATTRIBUTE_GROUPS(dump_default);
212
213static const struct kobj_type dump_ktype = {
214 .sysfs_ops = &dump_sysfs_ops,
215 .release = &dump_release,
216 .default_groups = dump_default_groups,
217};
218
219static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
220{
221 __be32 id, size, type;
222 int rc;
223
224 type = cpu_to_be32(0xffffffff);
225
226 rc = opal_dump_info2(&id, &size, &type);
227 if (rc == OPAL_PARAMETER)
228 rc = opal_dump_info(&id, &size);
229
230 if (rc) {
231 pr_warn("%s: Failed to get dump info (%d)\n",
232 __func__, rc);
233 return rc;
234 }
235
236 *dump_id = be32_to_cpu(id);
237 *dump_size = be32_to_cpu(size);
238 *dump_type = be32_to_cpu(type);
239
240 return rc;
241}
242
243static int64_t dump_read_data(struct dump_obj *dump)
244{
245 struct opal_sg_list *list;
246 uint64_t addr;
247 int64_t rc;
248
249 /* Allocate memory */
250 dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
251 if (!dump->buffer) {
252 pr_err("%s : Failed to allocate memory\n", __func__);
253 rc = -ENOMEM;
254 goto out;
255 }
256
257 /* Generate SG list */
258 list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
259 if (!list) {
260 rc = -ENOMEM;
261 goto out;
262 }
263
264 /* First entry address */
265 addr = __pa(list);
266
267 /* Fetch data */
268 rc = OPAL_BUSY_EVENT;
269 while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
270 rc = opal_dump_read(dump->id, addr);
271 if (rc == OPAL_BUSY_EVENT) {
272 opal_poll_events(NULL);
273 msleep(msecs: 20);
274 }
275 }
276
277 if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
278 pr_warn("%s: Extract dump failed for ID 0x%x\n",
279 __func__, dump->id);
280
281 /* Free SG list */
282 opal_free_sg_list(list);
283
284out:
285 return rc;
286}
287
288static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
289 const struct bin_attribute *bin_attr,
290 char *buffer, loff_t pos, size_t count)
291{
292 ssize_t rc;
293
294 struct dump_obj *dump = to_dump_obj(kobj);
295
296 if (!dump->buffer) {
297 rc = dump_read_data(dump);
298
299 if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
300 vfree(addr: dump->buffer);
301 dump->buffer = NULL;
302
303 return -EIO;
304 }
305 if (rc == OPAL_PARTIAL) {
306 /* On a partial read, we just return EIO
307 * and rely on userspace to ask us to try
308 * again.
309 */
310 pr_info("%s: Platform dump partially read. ID = 0x%x\n",
311 __func__, dump->id);
312 return -EIO;
313 }
314 }
315
316 memcpy(buffer, dump->buffer + pos, count);
317
318 /* You may think we could free the dump buffer now and retrieve
319 * it again later if needed, but due to current firmware limitation,
320 * that's not the case. So, once read into userspace once,
321 * we keep the dump around until it's acknowledged by userspace.
322 */
323
324 return count;
325}
326
327static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
328{
329 struct dump_obj *dump;
330 int rc;
331
332 dump = kzalloc(sizeof(*dump), GFP_KERNEL);
333 if (!dump)
334 return;
335
336 dump->kobj.kset = dump_kset;
337
338 kobject_init(kobj: &dump->kobj, ktype: &dump_ktype);
339
340 sysfs_bin_attr_init(&dump->dump_attr);
341
342 dump->dump_attr.attr.name = "dump";
343 dump->dump_attr.attr.mode = 0400;
344 dump->dump_attr.size = size;
345 dump->dump_attr.read = dump_attr_read;
346
347 dump->id = id;
348 dump->size = size;
349 dump->type = type;
350
351 rc = kobject_add(kobj: &dump->kobj, NULL, fmt: "0x%x-0x%x", type, id);
352 if (rc) {
353 kobject_put(kobj: &dump->kobj);
354 return;
355 }
356
357 /*
358 * As soon as the sysfs file for this dump is created/activated there is
359 * a chance the opal_errd daemon (or any userspace) might read and
360 * acknowledge the dump before kobject_uevent() is called. If that
361 * happens then there is a potential race between
362 * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
363 * use-after-free of a kernfs object resulting in a kernel crash.
364 *
365 * To avoid that, we need to take a reference on behalf of the bin file,
366 * so that our reference remains valid while we call kobject_uevent().
367 * We then drop our reference before exiting the function, leaving the
368 * bin file to drop the last reference (if it hasn't already).
369 */
370
371 /* Take a reference for the bin file */
372 kobject_get(kobj: &dump->kobj);
373 rc = sysfs_create_bin_file(kobj: &dump->kobj, attr: &dump->dump_attr);
374 if (rc == 0) {
375 kobject_uevent(kobj: &dump->kobj, action: KOBJ_ADD);
376
377 pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
378 __func__, dump->id, dump->size);
379 } else {
380 /* Drop reference count taken for bin file */
381 kobject_put(kobj: &dump->kobj);
382 }
383
384 /* Drop our reference */
385 kobject_put(kobj: &dump->kobj);
386 return;
387}
388
389static irqreturn_t process_dump(int irq, void *data)
390{
391 int rc;
392 uint32_t dump_id, dump_size, dump_type;
393 char name[22];
394 struct kobject *kobj;
395
396 rc = dump_read_info(dump_id: &dump_id, dump_size: &dump_size, dump_type: &dump_type);
397 if (rc != OPAL_SUCCESS)
398 return IRQ_HANDLED;
399
400 sprintf(buf: name, fmt: "0x%x-0x%x", dump_type, dump_id);
401
402 /* we may get notified twice, let's handle
403 * that gracefully and not create two conflicting
404 * entries.
405 */
406 kobj = kset_find_obj(dump_kset, name);
407 if (kobj) {
408 /* Drop reference added by kset_find_obj() */
409 kobject_put(kobj);
410 return IRQ_HANDLED;
411 }
412
413 create_dump_obj(id: dump_id, size: dump_size, type: dump_type);
414
415 return IRQ_HANDLED;
416}
417
418void __init opal_platform_dump_init(void)
419{
420 int rc;
421 int dump_irq;
422
423 /* Dump not supported by firmware */
424 if (!opal_check_token(OPAL_DUMP_READ))
425 return;
426
427 dump_kset = kset_create_and_add(name: "dump", NULL, parent_kobj: opal_kobj);
428 if (!dump_kset) {
429 pr_warn("%s: Failed to create dump kset\n", __func__);
430 return;
431 }
432
433 rc = sysfs_create_group(kobj: &dump_kset->kobj, grp: &initiate_attr_group);
434 if (rc) {
435 pr_warn("%s: Failed to create initiate dump attr group\n",
436 __func__);
437 kobject_put(kobj: &dump_kset->kobj);
438 return;
439 }
440
441 dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
442 if (!dump_irq) {
443 pr_err("%s: Can't register OPAL event irq (%d)\n",
444 __func__, dump_irq);
445 return;
446 }
447
448 rc = request_threaded_irq(irq: dump_irq, NULL, thread_fn: process_dump,
449 IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
450 name: "opal-dump", NULL);
451 if (rc) {
452 pr_err("%s: Can't request OPAL event irq (%d)\n",
453 __func__, rc);
454 return;
455 }
456
457 if (opal_check_token(OPAL_DUMP_RESEND))
458 opal_dump_resend_notification();
459}
460

source code of linux/arch/powerpc/platforms/powernv/opal-dump.c