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/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 
55 static DEFINE_MUTEX(hsa_buf_mutex);
56 static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
57 
58 /*
59  * Copy memory from HSA to iterator (not reentrant):
60  *
61  * @iter:  Iterator where memory should be copied to
62  * @src:   Start address within HSA where data should be copied
63  * @count: Size of buffer, which should be copied
64  */
memcpy_hsa_iter(struct iov_iter * iter,unsigned long src,size_t count)65 size_t memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count)
66 {
67 	size_t bytes, copied, res = 0;
68 	unsigned long offset;
69 
70 	if (!hsa_available)
71 		return 0;
72 
73 	mutex_lock(&hsa_buf_mutex);
74 	while (count) {
75 		if (sclp_sdias_copy(hsa_buf, src / PAGE_SIZE + 2, 1)) {
76 			TRACE("sclp_sdias_copy() failed\n");
77 			break;
78 		}
79 		offset = src % PAGE_SIZE;
80 		bytes = min(PAGE_SIZE - offset, count);
81 		copied = copy_to_iter(hsa_buf + offset, bytes, iter);
82 		count -= copied;
83 		src += copied;
84 		res += copied;
85 		if (copied < bytes)
86 			break;
87 	}
88 	mutex_unlock(&hsa_buf_mutex);
89 	return res;
90 }
91 
92 /*
93  * Copy memory from HSA to kernel memory (not reentrant):
94  *
95  * @dest:  Kernel or user buffer where memory should be copied to
96  * @src:   Start address within HSA where data should be copied
97  * @count: Size of buffer, which should be copied
98  */
memcpy_hsa_kernel(void * dst,unsigned long src,size_t count)99 static inline int memcpy_hsa_kernel(void *dst, unsigned long src, size_t count)
100 {
101 	struct iov_iter iter;
102 	struct kvec kvec;
103 
104 	kvec.iov_base = dst;
105 	kvec.iov_len = count;
106 	iov_iter_kvec(&iter, WRITE, &kvec, 1, count);
107 	if (memcpy_hsa_iter(&iter, src, count) < count)
108 		return -EIO;
109 	return 0;
110 }
111 
init_cpu_info(void)112 static int __init init_cpu_info(void)
113 {
114 	struct save_area *sa;
115 
116 	/* get info for boot cpu from lowcore, stored in the HSA */
117 	sa = save_area_boot_cpu();
118 	if (!sa)
119 		return -ENOMEM;
120 	if (memcpy_hsa_kernel(hsa_buf, __LC_FPREGS_SAVE_AREA, 512) < 0) {
121 		TRACE("could not copy from HSA\n");
122 		return -EIO;
123 	}
124 	save_area_add_regs(sa, hsa_buf); /* vx registers are saved in smp.c */
125 	return 0;
126 }
127 
128 /*
129  * Release the HSA
130  */
release_hsa(void)131 static void release_hsa(void)
132 {
133 	diag308(DIAG308_REL_HSA, NULL);
134 	hsa_available = 0;
135 }
136 
zcore_reipl_write(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)137 static ssize_t zcore_reipl_write(struct file *filp, const char __user *buf,
138 				 size_t count, loff_t *ppos)
139 {
140 	if (zcore_ipl_block) {
141 		diag308(DIAG308_SET, zcore_ipl_block);
142 		diag308(DIAG308_LOAD_CLEAR, NULL);
143 	}
144 	return count;
145 }
146 
zcore_reipl_open(struct inode * inode,struct file * filp)147 static int zcore_reipl_open(struct inode *inode, struct file *filp)
148 {
149 	return stream_open(inode, filp);
150 }
151 
zcore_reipl_release(struct inode * inode,struct file * filp)152 static int zcore_reipl_release(struct inode *inode, struct file *filp)
153 {
154 	return 0;
155 }
156 
157 static const struct file_operations zcore_reipl_fops = {
158 	.owner		= THIS_MODULE,
159 	.write		= zcore_reipl_write,
160 	.open		= zcore_reipl_open,
161 	.release	= zcore_reipl_release,
162 	.llseek		= no_llseek,
163 };
164 
zcore_hsa_read(struct file * filp,char __user * buf,size_t count,loff_t * ppos)165 static ssize_t zcore_hsa_read(struct file *filp, char __user *buf,
166 			      size_t count, loff_t *ppos)
167 {
168 	static char str[18];
169 
170 	if (hsa_available)
171 		snprintf(str, sizeof(str), "%lx\n", sclp.hsa_size);
172 	else
173 		snprintf(str, sizeof(str), "0\n");
174 	return simple_read_from_buffer(buf, count, ppos, str, strlen(str));
175 }
176 
zcore_hsa_write(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)177 static ssize_t zcore_hsa_write(struct file *filp, const char __user *buf,
178 			       size_t count, loff_t *ppos)
179 {
180 	char value;
181 
182 	if (*ppos != 0)
183 		return -EPIPE;
184 	if (copy_from_user(&value, buf, 1))
185 		return -EFAULT;
186 	if (value != '0')
187 		return -EINVAL;
188 	release_hsa();
189 	return count;
190 }
191 
192 static const struct file_operations zcore_hsa_fops = {
193 	.owner		= THIS_MODULE,
194 	.write		= zcore_hsa_write,
195 	.read		= zcore_hsa_read,
196 	.open		= nonseekable_open,
197 	.llseek		= no_llseek,
198 };
199 
check_sdias(void)200 static int __init check_sdias(void)
201 {
202 	if (!sclp.hsa_size) {
203 		TRACE("Could not determine HSA size\n");
204 		return -ENODEV;
205 	}
206 	return 0;
207 }
208 
209 /*
210  * Provide IPL parameter information block from either HSA or memory
211  * for future reipl
212  */
zcore_reipl_init(void)213 static int __init zcore_reipl_init(void)
214 {
215 	struct ipib_info ipib_info;
216 	int rc;
217 
218 	rc = memcpy_hsa_kernel(&ipib_info, __LC_DUMP_REIPL, sizeof(ipib_info));
219 	if (rc)
220 		return rc;
221 	if (ipib_info.ipib == 0)
222 		return 0;
223 	zcore_ipl_block = (void *) __get_free_page(GFP_KERNEL);
224 	if (!zcore_ipl_block)
225 		return -ENOMEM;
226 	if (ipib_info.ipib < sclp.hsa_size)
227 		rc = memcpy_hsa_kernel(zcore_ipl_block, ipib_info.ipib,
228 				       PAGE_SIZE);
229 	else
230 		rc = memcpy_real(zcore_ipl_block, ipib_info.ipib, PAGE_SIZE);
231 	if (rc || (__force u32)csum_partial(zcore_ipl_block, zcore_ipl_block->hdr.len, 0) !=
232 	    ipib_info.checksum) {
233 		TRACE("Checksum does not match\n");
234 		free_page((unsigned long) zcore_ipl_block);
235 		zcore_ipl_block = NULL;
236 	}
237 	return 0;
238 }
239 
zcore_reboot_and_on_panic_handler(struct notifier_block * self,unsigned long event,void * data)240 static int zcore_reboot_and_on_panic_handler(struct notifier_block *self,
241 					     unsigned long	   event,
242 					     void		   *data)
243 {
244 	if (hsa_available)
245 		release_hsa();
246 
247 	return NOTIFY_OK;
248 }
249 
250 static struct notifier_block zcore_reboot_notifier = {
251 	.notifier_call	= zcore_reboot_and_on_panic_handler,
252 	/* we need to be notified before reipl and kdump */
253 	.priority	= INT_MAX,
254 };
255 
256 static struct notifier_block zcore_on_panic_notifier = {
257 	.notifier_call	= zcore_reboot_and_on_panic_handler,
258 	/* we need to be notified before reipl and kdump */
259 	.priority	= INT_MAX,
260 };
261 
zcore_init(void)262 static int __init zcore_init(void)
263 {
264 	unsigned char arch;
265 	int rc;
266 
267 	if (!is_ipl_type_dump())
268 		return -ENODATA;
269 	if (oldmem_data.start)
270 		return -ENODATA;
271 
272 	zcore_dbf = debug_register("zcore", 4, 1, 4 * sizeof(long));
273 	debug_register_view(zcore_dbf, &debug_sprintf_view);
274 	debug_set_level(zcore_dbf, 6);
275 
276 	if (ipl_info.type == IPL_TYPE_FCP_DUMP) {
277 		TRACE("type:   fcp\n");
278 		TRACE("devno:  %x\n", ipl_info.data.fcp.dev_id.devno);
279 		TRACE("wwpn:   %llx\n", (unsigned long long) ipl_info.data.fcp.wwpn);
280 		TRACE("lun:    %llx\n", (unsigned long long) ipl_info.data.fcp.lun);
281 	} else if (ipl_info.type == IPL_TYPE_NVME_DUMP) {
282 		TRACE("type:   nvme\n");
283 		TRACE("fid:    %x\n", ipl_info.data.nvme.fid);
284 		TRACE("nsid:   %x\n", ipl_info.data.nvme.nsid);
285 	}
286 
287 	rc = sclp_sdias_init();
288 	if (rc)
289 		goto fail;
290 
291 	rc = check_sdias();
292 	if (rc)
293 		goto fail;
294 	hsa_available = 1;
295 
296 	rc = memcpy_hsa_kernel(&arch, __LC_AR_MODE_ID, 1);
297 	if (rc)
298 		goto fail;
299 
300 	if (arch == ARCH_S390) {
301 		pr_alert("The 64-bit dump tool cannot be used for a "
302 			 "32-bit system\n");
303 		rc = -EINVAL;
304 		goto fail;
305 	}
306 
307 	pr_alert("The dump process started for a 64-bit operating system\n");
308 	rc = init_cpu_info();
309 	if (rc)
310 		goto fail;
311 
312 	rc = zcore_reipl_init();
313 	if (rc)
314 		goto fail;
315 
316 	zcore_dir = debugfs_create_dir("zcore" , NULL);
317 	zcore_reipl_file = debugfs_create_file("reipl", S_IRUSR, zcore_dir,
318 						NULL, &zcore_reipl_fops);
319 	zcore_hsa_file = debugfs_create_file("hsa", S_IRUSR|S_IWUSR, zcore_dir,
320 					     NULL, &zcore_hsa_fops);
321 
322 	register_reboot_notifier(&zcore_reboot_notifier);
323 	atomic_notifier_chain_register(&panic_notifier_list, &zcore_on_panic_notifier);
324 
325 	return 0;
326 fail:
327 	diag308(DIAG308_REL_HSA, NULL);
328 	return rc;
329 }
330 subsys_initcall(zcore_init);
331