xref: /openbmc/linux/drivers/s390/char/zcore.c (revision 37002bc6)
1 // SPDX-License-Identifier: GPL-1.0+
2 /*
3  * zcore module to export memory content and register sets for creating system
4  * dumps on SCSI/NVMe disks (zfcp/nvme dump).
5  *
6  * For more information please refer to Documentation/arch/s390/zfcpdump.rst
7  *
8  * Copyright IBM Corp. 2003, 2008
9  * Author(s): Michael Holzheu
10  */
11 
12 #define KMSG_COMPONENT "zdump"
13 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
14 
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/debugfs.h>
18 #include <linux/panic_notifier.h>
19 #include <linux/reboot.h>
20 #include <linux/uio.h>
21 
22 #include <asm/asm-offsets.h>
23 #include <asm/ipl.h>
24 #include <asm/sclp.h>
25 #include <asm/setup.h>
26 #include <linux/uaccess.h>
27 #include <asm/debug.h>
28 #include <asm/processor.h>
29 #include <asm/irqflags.h>
30 #include <asm/checksum.h>
31 #include <asm/os_info.h>
32 #include <asm/switch_to.h>
33 #include <asm/maccess.h>
34 #include "sclp.h"
35 
36 #define TRACE(x...) debug_sprintf_event(zcore_dbf, 1, x)
37 
38 enum arch_id {
39 	ARCH_S390	= 0,
40 	ARCH_S390X	= 1,
41 };
42 
43 struct ipib_info {
44 	unsigned long	ipib;
45 	u32		checksum;
46 }  __attribute__((packed));
47 
48 static struct debug_info *zcore_dbf;
49 static int hsa_available;
50 static struct dentry *zcore_dir;
51 static struct dentry *zcore_reipl_file;
52 static struct dentry *zcore_hsa_file;
53 static struct ipl_parameter_block *zcore_ipl_block;
54 static unsigned long os_info_flags;
55 
56 static DEFINE_MUTEX(hsa_buf_mutex);
57 static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
58 
59 /*
60  * Copy memory from HSA to iterator (not reentrant):
61  *
62  * @iter:  Iterator where memory should be copied to
63  * @src:   Start address within HSA where data should be copied
64  * @count: Size of buffer, which should be copied
65  */
memcpy_hsa_iter(struct iov_iter * iter,unsigned long src,size_t count)66 size_t memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count)
67 {
68 	size_t bytes, copied, res = 0;
69 	unsigned long offset;
70 
71 	if (!hsa_available)
72 		return 0;
73 
74 	mutex_lock(&hsa_buf_mutex);
75 	while (count) {
76 		if (sclp_sdias_copy(hsa_buf, src / PAGE_SIZE + 2, 1)) {
77 			TRACE("sclp_sdias_copy() failed\n");
78 			break;
79 		}
80 		offset = src % PAGE_SIZE;
81 		bytes = min(PAGE_SIZE - offset, count);
82 		copied = copy_to_iter(hsa_buf + offset, bytes, iter);
83 		count -= copied;
84 		src += copied;
85 		res += copied;
86 		if (copied < bytes)
87 			break;
88 	}
89 	mutex_unlock(&hsa_buf_mutex);
90 	return res;
91 }
92 
93 /*
94  * Copy memory from HSA to kernel memory (not reentrant):
95  *
96  * @dest:  Kernel or user buffer where memory should be copied to
97  * @src:   Start address within HSA where data should be copied
98  * @count: Size of buffer, which should be copied
99  */
memcpy_hsa_kernel(void * dst,unsigned long src,size_t count)100 static inline int memcpy_hsa_kernel(void *dst, unsigned long src, size_t count)
101 {
102 	struct iov_iter iter;
103 	struct kvec kvec;
104 
105 	kvec.iov_base = dst;
106 	kvec.iov_len = count;
107 	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
108 	if (memcpy_hsa_iter(&iter, src, count) < count)
109 		return -EIO;
110 	return 0;
111 }
112 
init_cpu_info(void)113 static int __init init_cpu_info(void)
114 {
115 	struct save_area *sa;
116 
117 	/* get info for boot cpu from lowcore, stored in the HSA */
118 	sa = save_area_boot_cpu();
119 	if (!sa)
120 		return -ENOMEM;
121 	if (memcpy_hsa_kernel(hsa_buf, __LC_FPREGS_SAVE_AREA, 512) < 0) {
122 		TRACE("could not copy from HSA\n");
123 		return -EIO;
124 	}
125 	save_area_add_regs(sa, hsa_buf); /* vx registers are saved in smp.c */
126 	return 0;
127 }
128 
129 /*
130  * Release the HSA
131  */
release_hsa(void)132 static void release_hsa(void)
133 {
134 	diag308(DIAG308_REL_HSA, NULL);
135 	hsa_available = 0;
136 }
137 
zcore_reipl_write(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)138 static ssize_t zcore_reipl_write(struct file *filp, const char __user *buf,
139 				 size_t count, loff_t *ppos)
140 {
141 	if (zcore_ipl_block) {
142 		diag308(DIAG308_SET, zcore_ipl_block);
143 		if (os_info_flags & OS_INFO_FLAG_REIPL_CLEAR)
144 			diag308(DIAG308_LOAD_CLEAR, NULL);
145 		/* Use special diag308 subcode for CCW normal ipl */
146 		if (zcore_ipl_block->pb0_hdr.pbt == IPL_PBT_CCW)
147 			diag308(DIAG308_LOAD_NORMAL_DUMP, NULL);
148 		else
149 			diag308(DIAG308_LOAD_NORMAL, NULL);
150 	}
151 	return count;
152 }
153 
zcore_reipl_open(struct inode * inode,struct file * filp)154 static int zcore_reipl_open(struct inode *inode, struct file *filp)
155 {
156 	return stream_open(inode, filp);
157 }
158 
zcore_reipl_release(struct inode * inode,struct file * filp)159 static int zcore_reipl_release(struct inode *inode, struct file *filp)
160 {
161 	return 0;
162 }
163 
164 static const struct file_operations zcore_reipl_fops = {
165 	.owner		= THIS_MODULE,
166 	.write		= zcore_reipl_write,
167 	.open		= zcore_reipl_open,
168 	.release	= zcore_reipl_release,
169 	.llseek		= no_llseek,
170 };
171 
zcore_hsa_read(struct file * filp,char __user * buf,size_t count,loff_t * ppos)172 static ssize_t zcore_hsa_read(struct file *filp, char __user *buf,
173 			      size_t count, loff_t *ppos)
174 {
175 	static char str[18];
176 
177 	if (hsa_available)
178 		snprintf(str, sizeof(str), "%lx\n", sclp.hsa_size);
179 	else
180 		snprintf(str, sizeof(str), "0\n");
181 	return simple_read_from_buffer(buf, count, ppos, str, strlen(str));
182 }
183 
zcore_hsa_write(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)184 static ssize_t zcore_hsa_write(struct file *filp, const char __user *buf,
185 			       size_t count, loff_t *ppos)
186 {
187 	char value;
188 
189 	if (*ppos != 0)
190 		return -EPIPE;
191 	if (copy_from_user(&value, buf, 1))
192 		return -EFAULT;
193 	if (value != '0')
194 		return -EINVAL;
195 	release_hsa();
196 	return count;
197 }
198 
199 static const struct file_operations zcore_hsa_fops = {
200 	.owner		= THIS_MODULE,
201 	.write		= zcore_hsa_write,
202 	.read		= zcore_hsa_read,
203 	.open		= nonseekable_open,
204 	.llseek		= no_llseek,
205 };
206 
check_sdias(void)207 static int __init check_sdias(void)
208 {
209 	if (!sclp.hsa_size) {
210 		TRACE("Could not determine HSA size\n");
211 		return -ENODEV;
212 	}
213 	return 0;
214 }
215 
216 /*
217  * Provide IPL parameter information block from either HSA or memory
218  * for future reipl
219  */
zcore_reipl_init(void)220 static int __init zcore_reipl_init(void)
221 {
222 	struct os_info_entry *entry;
223 	struct ipib_info ipib_info;
224 	unsigned long os_info_addr;
225 	struct os_info *os_info;
226 	int rc;
227 
228 	rc = memcpy_hsa_kernel(&ipib_info, __LC_DUMP_REIPL, sizeof(ipib_info));
229 	if (rc)
230 		return rc;
231 	if (ipib_info.ipib == 0)
232 		return 0;
233 	zcore_ipl_block = (void *) __get_free_page(GFP_KERNEL);
234 	if (!zcore_ipl_block)
235 		return -ENOMEM;
236 	if (ipib_info.ipib < sclp.hsa_size)
237 		rc = memcpy_hsa_kernel(zcore_ipl_block, ipib_info.ipib,
238 				       PAGE_SIZE);
239 	else
240 		rc = memcpy_real(zcore_ipl_block, ipib_info.ipib, PAGE_SIZE);
241 	if (rc || (__force u32)csum_partial(zcore_ipl_block, zcore_ipl_block->hdr.len, 0) !=
242 	    ipib_info.checksum) {
243 		TRACE("Checksum does not match\n");
244 		free_page((unsigned long) zcore_ipl_block);
245 		zcore_ipl_block = NULL;
246 	}
247 	/*
248 	 * Read the bit-flags field from os_info flags entry.
249 	 * Return zero even for os_info read or entry checksum errors in order
250 	 * to continue dump processing, considering that os_info could be
251 	 * corrupted on the panicked system.
252 	 */
253 	os_info = (void *)__get_free_page(GFP_KERNEL);
254 	if (!os_info)
255 		return -ENOMEM;
256 	rc = memcpy_hsa_kernel(&os_info_addr, __LC_OS_INFO, sizeof(os_info_addr));
257 	if (rc)
258 		goto out;
259 	if (os_info_addr < sclp.hsa_size)
260 		rc = memcpy_hsa_kernel(os_info, os_info_addr, PAGE_SIZE);
261 	else
262 		rc = memcpy_real(os_info, os_info_addr, PAGE_SIZE);
263 	if (rc || os_info_csum(os_info) != os_info->csum)
264 		goto out;
265 	entry = &os_info->entry[OS_INFO_FLAGS_ENTRY];
266 	if (entry->addr && entry->size) {
267 		if (entry->addr < sclp.hsa_size)
268 			rc = memcpy_hsa_kernel(&os_info_flags, entry->addr, sizeof(os_info_flags));
269 		else
270 			rc = memcpy_real(&os_info_flags, entry->addr, sizeof(os_info_flags));
271 		if (rc || (__force u32)csum_partial(&os_info_flags, entry->size, 0) != entry->csum)
272 			os_info_flags = 0;
273 	}
274 out:
275 	free_page((unsigned long)os_info);
276 	return 0;
277 }
278 
zcore_reboot_and_on_panic_handler(struct notifier_block * self,unsigned long event,void * data)279 static int zcore_reboot_and_on_panic_handler(struct notifier_block *self,
280 					     unsigned long	   event,
281 					     void		   *data)
282 {
283 	if (hsa_available)
284 		release_hsa();
285 
286 	return NOTIFY_OK;
287 }
288 
289 static struct notifier_block zcore_reboot_notifier = {
290 	.notifier_call	= zcore_reboot_and_on_panic_handler,
291 	/* we need to be notified before reipl and kdump */
292 	.priority	= INT_MAX,
293 };
294 
295 static struct notifier_block zcore_on_panic_notifier = {
296 	.notifier_call	= zcore_reboot_and_on_panic_handler,
297 	/* we need to be notified before reipl and kdump */
298 	.priority	= INT_MAX,
299 };
300 
zcore_init(void)301 static int __init zcore_init(void)
302 {
303 	unsigned char arch;
304 	int rc;
305 
306 	if (!is_ipl_type_dump())
307 		return -ENODATA;
308 	if (oldmem_data.start)
309 		return -ENODATA;
310 
311 	zcore_dbf = debug_register("zcore", 4, 1, 4 * sizeof(long));
312 	debug_register_view(zcore_dbf, &debug_sprintf_view);
313 	debug_set_level(zcore_dbf, 6);
314 
315 	if (ipl_info.type == IPL_TYPE_FCP_DUMP) {
316 		TRACE("type:   fcp\n");
317 		TRACE("devno:  %x\n", ipl_info.data.fcp.dev_id.devno);
318 		TRACE("wwpn:   %llx\n", (unsigned long long) ipl_info.data.fcp.wwpn);
319 		TRACE("lun:    %llx\n", (unsigned long long) ipl_info.data.fcp.lun);
320 	} else if (ipl_info.type == IPL_TYPE_NVME_DUMP) {
321 		TRACE("type:   nvme\n");
322 		TRACE("fid:    %x\n", ipl_info.data.nvme.fid);
323 		TRACE("nsid:   %x\n", ipl_info.data.nvme.nsid);
324 	} else if (ipl_info.type == IPL_TYPE_ECKD_DUMP) {
325 		TRACE("type:   eckd\n");
326 		TRACE("devno:  %x\n", ipl_info.data.eckd.dev_id.devno);
327 		TRACE("ssid:   %x\n", ipl_info.data.eckd.dev_id.ssid);
328 	}
329 
330 	rc = sclp_sdias_init();
331 	if (rc)
332 		goto fail;
333 
334 	rc = check_sdias();
335 	if (rc)
336 		goto fail;
337 	hsa_available = 1;
338 
339 	rc = memcpy_hsa_kernel(&arch, __LC_AR_MODE_ID, 1);
340 	if (rc)
341 		goto fail;
342 
343 	if (arch == ARCH_S390) {
344 		pr_alert("The 64-bit dump tool cannot be used for a "
345 			 "32-bit system\n");
346 		rc = -EINVAL;
347 		goto fail;
348 	}
349 
350 	pr_alert("The dump process started for a 64-bit operating system\n");
351 	rc = init_cpu_info();
352 	if (rc)
353 		goto fail;
354 
355 	rc = zcore_reipl_init();
356 	if (rc)
357 		goto fail;
358 
359 	zcore_dir = debugfs_create_dir("zcore" , NULL);
360 	zcore_reipl_file = debugfs_create_file("reipl", S_IRUSR, zcore_dir,
361 						NULL, &zcore_reipl_fops);
362 	zcore_hsa_file = debugfs_create_file("hsa", S_IRUSR|S_IWUSR, zcore_dir,
363 					     NULL, &zcore_hsa_fops);
364 
365 	register_reboot_notifier(&zcore_reboot_notifier);
366 	atomic_notifier_chain_register(&panic_notifier_list, &zcore_on_panic_notifier);
367 
368 	return 0;
369 fail:
370 	diag308(DIAG308_REL_HSA, NULL);
371 	return rc;
372 }
373 subsys_initcall(zcore_init);
374