xref: /linux/arch/s390/kernel/crash_dump.c (revision 955abe0a1b41de5ba61fe4cd614ebc123084d499)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * S390 kdump implementation
4  *
5  * Copyright IBM Corp. 2011
6  * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
7  */
8 
9 #include <linux/crash_dump.h>
10 #include <asm/lowcore.h>
11 #include <linux/kernel.h>
12 #include <linux/init.h>
13 #include <linux/mm.h>
14 #include <linux/gfp.h>
15 #include <linux/slab.h>
16 #include <linux/memblock.h>
17 #include <linux/elf.h>
18 #include <linux/uio.h>
19 #include <asm/asm-offsets.h>
20 #include <asm/os_info.h>
21 #include <asm/elf.h>
22 #include <asm/ipl.h>
23 #include <asm/sclp.h>
24 #include <asm/maccess.h>
25 #include <asm/fpu.h>
26 
27 #define PTR_ADD(x, y) (((char *) (x)) + ((unsigned long) (y)))
28 #define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
29 #define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y))))
30 
31 static struct memblock_region oldmem_region;
32 
33 static struct memblock_type oldmem_type = {
34 	.cnt = 1,
35 	.max = 1,
36 	.total_size = 0,
37 	.regions = &oldmem_region,
38 	.name = "oldmem",
39 };
40 
41 struct save_area {
42 	struct list_head list;
43 	u64 psw[2];
44 	u64 ctrs[16];
45 	u64 gprs[16];
46 	u32 acrs[16];
47 	u64 fprs[16];
48 	u32 fpc;
49 	u32 prefix;
50 	u32 todpreg;
51 	u64 timer;
52 	u64 todcmp;
53 	u64 vxrs_low[16];
54 	__vector128 vxrs_high[16];
55 };
56 
57 static LIST_HEAD(dump_save_areas);
58 
59 /*
60  * Allocate a save area
61  */
62 struct save_area * __init save_area_alloc(bool is_boot_cpu)
63 {
64 	struct save_area *sa;
65 
66 	sa = memblock_alloc(sizeof(*sa), 8);
67 	if (!sa)
68 		return NULL;
69 
70 	if (is_boot_cpu)
71 		list_add(&sa->list, &dump_save_areas);
72 	else
73 		list_add_tail(&sa->list, &dump_save_areas);
74 	return sa;
75 }
76 
77 /*
78  * Return the address of the save area for the boot CPU
79  */
80 struct save_area * __init save_area_boot_cpu(void)
81 {
82 	return list_first_entry_or_null(&dump_save_areas, struct save_area, list);
83 }
84 
85 /*
86  * Copy CPU registers into the save area
87  */
88 void __init save_area_add_regs(struct save_area *sa, void *regs)
89 {
90 	struct lowcore *lc;
91 
92 	lc = (struct lowcore *)(regs - __LC_FPREGS_SAVE_AREA);
93 	memcpy(&sa->psw, &lc->psw_save_area, sizeof(sa->psw));
94 	memcpy(&sa->ctrs, &lc->cregs_save_area, sizeof(sa->ctrs));
95 	memcpy(&sa->gprs, &lc->gpregs_save_area, sizeof(sa->gprs));
96 	memcpy(&sa->acrs, &lc->access_regs_save_area, sizeof(sa->acrs));
97 	memcpy(&sa->fprs, &lc->floating_pt_save_area, sizeof(sa->fprs));
98 	memcpy(&sa->fpc, &lc->fpt_creg_save_area, sizeof(sa->fpc));
99 	memcpy(&sa->prefix, &lc->prefixreg_save_area, sizeof(sa->prefix));
100 	memcpy(&sa->todpreg, &lc->tod_progreg_save_area, sizeof(sa->todpreg));
101 	memcpy(&sa->timer, &lc->cpu_timer_save_area, sizeof(sa->timer));
102 	memcpy(&sa->todcmp, &lc->clock_comp_save_area, sizeof(sa->todcmp));
103 }
104 
105 /*
106  * Copy vector registers into the save area
107  */
108 void __init save_area_add_vxrs(struct save_area *sa, __vector128 *vxrs)
109 {
110 	int i;
111 
112 	/* Copy lower halves of vector registers 0-15 */
113 	for (i = 0; i < 16; i++)
114 		sa->vxrs_low[i] = vxrs[i].low;
115 	/* Copy vector registers 16-31 */
116 	memcpy(sa->vxrs_high, vxrs + 16, 16 * sizeof(__vector128));
117 }
118 
119 static size_t copy_oldmem_iter(struct iov_iter *iter, unsigned long src, size_t count)
120 {
121 	size_t len, copied, res = 0;
122 
123 	while (count) {
124 		if (!oldmem_data.start && src < sclp.hsa_size) {
125 			/* Copy from zfcp/nvme dump HSA area */
126 			len = min(count, sclp.hsa_size - src);
127 			copied = memcpy_hsa_iter(iter, src, len);
128 		} else {
129 			/* Check for swapped kdump oldmem areas */
130 			if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
131 				src -= oldmem_data.start;
132 				len = min(count, oldmem_data.size - src);
133 			} else if (oldmem_data.start && src < oldmem_data.size) {
134 				len = min(count, oldmem_data.size - src);
135 				src += oldmem_data.start;
136 			} else {
137 				len = count;
138 			}
139 			copied = memcpy_real_iter(iter, src, len);
140 		}
141 		count -= copied;
142 		src += copied;
143 		res += copied;
144 		if (copied < len)
145 			break;
146 	}
147 	return res;
148 }
149 
150 int copy_oldmem_kernel(void *dst, unsigned long src, size_t count)
151 {
152 	struct iov_iter iter;
153 	struct kvec kvec;
154 
155 	kvec.iov_base = dst;
156 	kvec.iov_len = count;
157 	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
158 	if (copy_oldmem_iter(&iter, src, count) < count)
159 		return -EFAULT;
160 	return 0;
161 }
162 
163 /*
164  * Copy one page from "oldmem"
165  */
166 ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
167 			 unsigned long offset)
168 {
169 	unsigned long src;
170 
171 	src = pfn_to_phys(pfn) + offset;
172 	return copy_oldmem_iter(iter, src, csize);
173 }
174 
175 /*
176  * Remap "oldmem" for kdump
177  *
178  * For the kdump reserved memory this functions performs a swap operation:
179  * [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE]
180  */
181 static int remap_oldmem_pfn_range_kdump(struct vm_area_struct *vma,
182 					unsigned long from, unsigned long pfn,
183 					unsigned long size, pgprot_t prot)
184 {
185 	unsigned long size_old;
186 	int rc;
187 
188 	if (pfn < oldmem_data.size >> PAGE_SHIFT) {
189 		size_old = min(size, oldmem_data.size - (pfn << PAGE_SHIFT));
190 		rc = remap_pfn_range(vma, from,
191 				     pfn + (oldmem_data.start >> PAGE_SHIFT),
192 				     size_old, prot);
193 		if (rc || size == size_old)
194 			return rc;
195 		size -= size_old;
196 		from += size_old;
197 		pfn += size_old >> PAGE_SHIFT;
198 	}
199 	return remap_pfn_range(vma, from, pfn, size, prot);
200 }
201 
202 /*
203  * Remap "oldmem" for zfcp/nvme dump
204  *
205  * We only map available memory above HSA size. Memory below HSA size
206  * is read on demand using the copy_oldmem_page() function.
207  */
208 static int remap_oldmem_pfn_range_zfcpdump(struct vm_area_struct *vma,
209 					   unsigned long from,
210 					   unsigned long pfn,
211 					   unsigned long size, pgprot_t prot)
212 {
213 	unsigned long hsa_end = sclp.hsa_size;
214 	unsigned long size_hsa;
215 
216 	if (pfn < hsa_end >> PAGE_SHIFT) {
217 		size_hsa = min(size, hsa_end - (pfn << PAGE_SHIFT));
218 		if (size == size_hsa)
219 			return 0;
220 		size -= size_hsa;
221 		from += size_hsa;
222 		pfn += size_hsa >> PAGE_SHIFT;
223 	}
224 	return remap_pfn_range(vma, from, pfn, size, prot);
225 }
226 
227 /*
228  * Remap "oldmem" for kdump or zfcp/nvme dump
229  */
230 int remap_oldmem_pfn_range(struct vm_area_struct *vma, unsigned long from,
231 			   unsigned long pfn, unsigned long size, pgprot_t prot)
232 {
233 	if (oldmem_data.start)
234 		return remap_oldmem_pfn_range_kdump(vma, from, pfn, size, prot);
235 	else
236 		return remap_oldmem_pfn_range_zfcpdump(vma, from, pfn, size,
237 						       prot);
238 }
239 
240 static const char *nt_name(Elf64_Word type)
241 {
242 	const char *name = "LINUX";
243 
244 	if (type == NT_PRPSINFO || type == NT_PRSTATUS || type == NT_PRFPREG)
245 		name = KEXEC_CORE_NOTE_NAME;
246 	return name;
247 }
248 
249 /*
250  * Initialize ELF note
251  */
252 static void *nt_init_name(void *buf, Elf64_Word type, void *desc, int d_len,
253 			  const char *name)
254 {
255 	Elf64_Nhdr *note;
256 	u64 len;
257 
258 	note = (Elf64_Nhdr *)buf;
259 	note->n_namesz = strlen(name) + 1;
260 	note->n_descsz = d_len;
261 	note->n_type = type;
262 	len = sizeof(Elf64_Nhdr);
263 
264 	memcpy(buf + len, name, note->n_namesz);
265 	len = roundup(len + note->n_namesz, 4);
266 
267 	memcpy(buf + len, desc, note->n_descsz);
268 	len = roundup(len + note->n_descsz, 4);
269 
270 	return PTR_ADD(buf, len);
271 }
272 
273 static inline void *nt_init(void *buf, Elf64_Word type, void *desc, int d_len)
274 {
275 	return nt_init_name(buf, type, desc, d_len, nt_name(type));
276 }
277 
278 /*
279  * Calculate the size of ELF note
280  */
281 static size_t nt_size_name(int d_len, const char *name)
282 {
283 	size_t size;
284 
285 	size = sizeof(Elf64_Nhdr);
286 	size += roundup(strlen(name) + 1, 4);
287 	size += roundup(d_len, 4);
288 
289 	return size;
290 }
291 
292 static inline size_t nt_size(Elf64_Word type, int d_len)
293 {
294 	return nt_size_name(d_len, nt_name(type));
295 }
296 
297 /*
298  * Fill ELF notes for one CPU with save area registers
299  */
300 static void *fill_cpu_elf_notes(void *ptr, int cpu, struct save_area *sa)
301 {
302 	struct elf_prstatus nt_prstatus;
303 	elf_fpregset_t nt_fpregset;
304 
305 	/* Prepare prstatus note */
306 	memset(&nt_prstatus, 0, sizeof(nt_prstatus));
307 	memcpy(&nt_prstatus.pr_reg.gprs, sa->gprs, sizeof(sa->gprs));
308 	memcpy(&nt_prstatus.pr_reg.psw, sa->psw, sizeof(sa->psw));
309 	memcpy(&nt_prstatus.pr_reg.acrs, sa->acrs, sizeof(sa->acrs));
310 	nt_prstatus.common.pr_pid = cpu;
311 	/* Prepare fpregset (floating point) note */
312 	memset(&nt_fpregset, 0, sizeof(nt_fpregset));
313 	memcpy(&nt_fpregset.fpc, &sa->fpc, sizeof(sa->fpc));
314 	memcpy(&nt_fpregset.fprs, &sa->fprs, sizeof(sa->fprs));
315 	/* Create ELF notes for the CPU */
316 	ptr = nt_init(ptr, NT_PRSTATUS, &nt_prstatus, sizeof(nt_prstatus));
317 	ptr = nt_init(ptr, NT_PRFPREG, &nt_fpregset, sizeof(nt_fpregset));
318 	ptr = nt_init(ptr, NT_S390_TIMER, &sa->timer, sizeof(sa->timer));
319 	ptr = nt_init(ptr, NT_S390_TODCMP, &sa->todcmp, sizeof(sa->todcmp));
320 	ptr = nt_init(ptr, NT_S390_TODPREG, &sa->todpreg, sizeof(sa->todpreg));
321 	ptr = nt_init(ptr, NT_S390_CTRS, &sa->ctrs, sizeof(sa->ctrs));
322 	ptr = nt_init(ptr, NT_S390_PREFIX, &sa->prefix, sizeof(sa->prefix));
323 	if (cpu_has_vx()) {
324 		ptr = nt_init(ptr, NT_S390_VXRS_HIGH,
325 			      &sa->vxrs_high, sizeof(sa->vxrs_high));
326 		ptr = nt_init(ptr, NT_S390_VXRS_LOW,
327 			      &sa->vxrs_low, sizeof(sa->vxrs_low));
328 	}
329 	return ptr;
330 }
331 
332 /*
333  * Calculate size of ELF notes per cpu
334  */
335 static size_t get_cpu_elf_notes_size(void)
336 {
337 	struct save_area *sa = NULL;
338 	size_t size;
339 
340 	size =	nt_size(NT_PRSTATUS, sizeof(struct elf_prstatus));
341 	size +=  nt_size(NT_PRFPREG, sizeof(elf_fpregset_t));
342 	size +=  nt_size(NT_S390_TIMER, sizeof(sa->timer));
343 	size +=  nt_size(NT_S390_TODCMP, sizeof(sa->todcmp));
344 	size +=  nt_size(NT_S390_TODPREG, sizeof(sa->todpreg));
345 	size +=  nt_size(NT_S390_CTRS, sizeof(sa->ctrs));
346 	size +=  nt_size(NT_S390_PREFIX, sizeof(sa->prefix));
347 	if (cpu_has_vx()) {
348 		size += nt_size(NT_S390_VXRS_HIGH, sizeof(sa->vxrs_high));
349 		size += nt_size(NT_S390_VXRS_LOW, sizeof(sa->vxrs_low));
350 	}
351 
352 	return size;
353 }
354 
355 /*
356  * Initialize prpsinfo note (new kernel)
357  */
358 static void *nt_prpsinfo(void *ptr)
359 {
360 	struct elf_prpsinfo prpsinfo;
361 
362 	memset(&prpsinfo, 0, sizeof(prpsinfo));
363 	prpsinfo.pr_sname = 'R';
364 	strcpy(prpsinfo.pr_fname, "vmlinux");
365 	return nt_init(ptr, NT_PRPSINFO, &prpsinfo, sizeof(prpsinfo));
366 }
367 
368 /*
369  * Get vmcoreinfo using lowcore->vmcore_info (new kernel)
370  */
371 static void *get_vmcoreinfo_old(unsigned long *size)
372 {
373 	char nt_name[11], *vmcoreinfo;
374 	unsigned long addr;
375 	Elf64_Nhdr note;
376 
377 	if (copy_oldmem_kernel(&addr, __LC_VMCORE_INFO, sizeof(addr)))
378 		return NULL;
379 	memset(nt_name, 0, sizeof(nt_name));
380 	if (copy_oldmem_kernel(&note, addr, sizeof(note)))
381 		return NULL;
382 	if (copy_oldmem_kernel(nt_name, addr + sizeof(note),
383 			       sizeof(nt_name) - 1))
384 		return NULL;
385 	if (strcmp(nt_name, VMCOREINFO_NOTE_NAME) != 0)
386 		return NULL;
387 	vmcoreinfo = kzalloc(note.n_descsz, GFP_KERNEL);
388 	if (!vmcoreinfo)
389 		return NULL;
390 	if (copy_oldmem_kernel(vmcoreinfo, addr + 24, note.n_descsz)) {
391 		kfree(vmcoreinfo);
392 		return NULL;
393 	}
394 	*size = note.n_descsz;
395 	return vmcoreinfo;
396 }
397 
398 /*
399  * Initialize vmcoreinfo note (new kernel)
400  */
401 static void *nt_vmcoreinfo(void *ptr)
402 {
403 	const char *name = VMCOREINFO_NOTE_NAME;
404 	unsigned long size;
405 	void *vmcoreinfo;
406 
407 	vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
408 	if (vmcoreinfo)
409 		return nt_init_name(ptr, 0, vmcoreinfo, size, name);
410 
411 	vmcoreinfo = get_vmcoreinfo_old(&size);
412 	if (!vmcoreinfo)
413 		return ptr;
414 	ptr = nt_init_name(ptr, 0, vmcoreinfo, size, name);
415 	kfree(vmcoreinfo);
416 	return ptr;
417 }
418 
419 static size_t nt_vmcoreinfo_size(void)
420 {
421 	const char *name = VMCOREINFO_NOTE_NAME;
422 	unsigned long size;
423 	void *vmcoreinfo;
424 
425 	vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
426 	if (vmcoreinfo)
427 		return nt_size_name(size, name);
428 
429 	vmcoreinfo = get_vmcoreinfo_old(&size);
430 	if (!vmcoreinfo)
431 		return 0;
432 
433 	kfree(vmcoreinfo);
434 	return nt_size_name(size, name);
435 }
436 
437 /*
438  * Initialize final note (needed for /proc/vmcore code)
439  */
440 static void *nt_final(void *ptr)
441 {
442 	Elf64_Nhdr *note;
443 
444 	note = (Elf64_Nhdr *) ptr;
445 	note->n_namesz = 0;
446 	note->n_descsz = 0;
447 	note->n_type = 0;
448 	return PTR_ADD(ptr, sizeof(Elf64_Nhdr));
449 }
450 
451 /*
452  * Initialize ELF header (new kernel)
453  */
454 static void *ehdr_init(Elf64_Ehdr *ehdr, int phdr_count)
455 {
456 	memset(ehdr, 0, sizeof(*ehdr));
457 	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
458 	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
459 	ehdr->e_ident[EI_DATA] = ELFDATA2MSB;
460 	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
461 	memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
462 	ehdr->e_type = ET_CORE;
463 	ehdr->e_machine = EM_S390;
464 	ehdr->e_version = EV_CURRENT;
465 	ehdr->e_phoff = sizeof(Elf64_Ehdr);
466 	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
467 	ehdr->e_phentsize = sizeof(Elf64_Phdr);
468 	/* Number of PT_LOAD program headers plus PT_NOTE program header */
469 	ehdr->e_phnum = phdr_count + 1;
470 	return ehdr + 1;
471 }
472 
473 /*
474  * Return CPU count for ELF header (new kernel)
475  */
476 static int get_cpu_cnt(void)
477 {
478 	struct save_area *sa;
479 	int cpus = 0;
480 
481 	list_for_each_entry(sa, &dump_save_areas, list)
482 		if (sa->prefix != 0)
483 			cpus++;
484 	return cpus;
485 }
486 
487 /*
488  * Return memory chunk count for ELF header (new kernel)
489  */
490 static int get_mem_chunk_cnt(void)
491 {
492 	int cnt = 0;
493 	u64 idx;
494 
495 	for_each_physmem_range(idx, &oldmem_type, NULL, NULL)
496 		cnt++;
497 	return cnt;
498 }
499 
500 /*
501  * Initialize ELF loads (new kernel)
502  */
503 static void loads_init(Elf64_Phdr *phdr, bool os_info_has_vm)
504 {
505 	unsigned long old_identity_base = 0;
506 	phys_addr_t start, end;
507 	u64 idx;
508 
509 	if (os_info_has_vm)
510 		old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE);
511 	for_each_physmem_range(idx, &oldmem_type, &start, &end) {
512 		phdr->p_type = PT_LOAD;
513 		phdr->p_vaddr = old_identity_base + start;
514 		phdr->p_offset = start;
515 		phdr->p_paddr = start;
516 		phdr->p_filesz = end - start;
517 		phdr->p_memsz = end - start;
518 		phdr->p_flags = PF_R | PF_W | PF_X;
519 		phdr->p_align = PAGE_SIZE;
520 		phdr++;
521 	}
522 }
523 
524 static bool os_info_has_vm(void)
525 {
526 	return os_info_old_value(OS_INFO_KASLR_OFFSET);
527 }
528 
529 /*
530  * Prepare PT_LOAD type program header for kernel image region
531  */
532 static void text_init(Elf64_Phdr *phdr)
533 {
534 	unsigned long start_phys = os_info_old_value(OS_INFO_IMAGE_PHYS);
535 	unsigned long start = os_info_old_value(OS_INFO_IMAGE_START);
536 	unsigned long end = os_info_old_value(OS_INFO_IMAGE_END);
537 
538 	phdr->p_type = PT_LOAD;
539 	phdr->p_vaddr = start;
540 	phdr->p_filesz = end - start;
541 	phdr->p_memsz = end - start;
542 	phdr->p_offset = start_phys;
543 	phdr->p_paddr = start_phys;
544 	phdr->p_flags = PF_R | PF_W | PF_X;
545 	phdr->p_align = PAGE_SIZE;
546 }
547 
548 /*
549  * Initialize notes (new kernel)
550  */
551 static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset)
552 {
553 	struct save_area *sa;
554 	void *ptr_start = ptr;
555 	int cpu;
556 
557 	ptr = nt_prpsinfo(ptr);
558 
559 	cpu = 1;
560 	list_for_each_entry(sa, &dump_save_areas, list)
561 		if (sa->prefix != 0)
562 			ptr = fill_cpu_elf_notes(ptr, cpu++, sa);
563 	ptr = nt_vmcoreinfo(ptr);
564 	ptr = nt_final(ptr);
565 	memset(phdr, 0, sizeof(*phdr));
566 	phdr->p_type = PT_NOTE;
567 	phdr->p_offset = notes_offset;
568 	phdr->p_filesz = (unsigned long) PTR_SUB(ptr, ptr_start);
569 	phdr->p_memsz = phdr->p_filesz;
570 	return ptr;
571 }
572 
573 static size_t get_elfcorehdr_size(int phdr_count)
574 {
575 	size_t size;
576 
577 	size = sizeof(Elf64_Ehdr);
578 	/* PT_NOTES */
579 	size += sizeof(Elf64_Phdr);
580 	/* nt_prpsinfo */
581 	size += nt_size(NT_PRPSINFO, sizeof(struct elf_prpsinfo));
582 	/* regsets */
583 	size += get_cpu_cnt() * get_cpu_elf_notes_size();
584 	/* nt_vmcoreinfo */
585 	size += nt_vmcoreinfo_size();
586 	/* nt_final */
587 	size += sizeof(Elf64_Nhdr);
588 	/* PT_LOADS */
589 	size += phdr_count * sizeof(Elf64_Phdr);
590 
591 	return size;
592 }
593 
594 /*
595  * Create ELF core header (new kernel)
596  */
597 int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
598 {
599 	Elf64_Phdr *phdr_notes, *phdr_loads, *phdr_text;
600 	int mem_chunk_cnt, phdr_text_cnt;
601 	size_t alloc_size;
602 	void *ptr, *hdr;
603 	u64 hdr_off;
604 
605 	/* If we are not in kdump or zfcp/nvme dump mode return */
606 	if (!oldmem_data.start && !is_ipl_type_dump())
607 		return 0;
608 	/* If we cannot get HSA size for zfcp/nvme dump return error */
609 	if (is_ipl_type_dump() && !sclp.hsa_size)
610 		return -ENODEV;
611 
612 	/* For kdump, exclude previous crashkernel memory */
613 	if (oldmem_data.start) {
614 		oldmem_region.base = oldmem_data.start;
615 		oldmem_region.size = oldmem_data.size;
616 		oldmem_type.total_size = oldmem_data.size;
617 	}
618 
619 	mem_chunk_cnt = get_mem_chunk_cnt();
620 	phdr_text_cnt = os_info_has_vm() ? 1 : 0;
621 
622 	alloc_size = get_elfcorehdr_size(mem_chunk_cnt + phdr_text_cnt);
623 
624 	hdr = kzalloc(alloc_size, GFP_KERNEL);
625 
626 	/*
627 	 * Without elfcorehdr /proc/vmcore cannot be created. Thus creating
628 	 * a dump with this crash kernel will fail. Panic now to allow other
629 	 * dump mechanisms to take over.
630 	 */
631 	if (!hdr)
632 		panic("s390 kdump allocating elfcorehdr failed");
633 
634 	/* Init elf header */
635 	phdr_notes = ehdr_init(hdr, mem_chunk_cnt + phdr_text_cnt);
636 	/* Init program headers */
637 	if (phdr_text_cnt) {
638 		phdr_text = phdr_notes + 1;
639 		phdr_loads = phdr_text + 1;
640 	} else {
641 		phdr_loads = phdr_notes + 1;
642 	}
643 	ptr = PTR_ADD(phdr_loads, sizeof(Elf64_Phdr) * mem_chunk_cnt);
644 	/* Init notes */
645 	hdr_off = PTR_DIFF(ptr, hdr);
646 	ptr = notes_init(phdr_notes, ptr, ((unsigned long) hdr) + hdr_off);
647 	/* Init kernel text program header */
648 	if (phdr_text_cnt)
649 		text_init(phdr_text);
650 	/* Init loads */
651 	loads_init(phdr_loads, phdr_text_cnt);
652 	/* Finalize program headers */
653 	hdr_off = PTR_DIFF(ptr, hdr);
654 	*addr = (unsigned long long) hdr;
655 	*size = (unsigned long long) hdr_off;
656 	BUG_ON(elfcorehdr_size > alloc_size);
657 	return 0;
658 }
659 
660 /*
661  * Free ELF core header (new kernel)
662  */
663 void elfcorehdr_free(unsigned long long addr)
664 {
665 	kfree((void *)(unsigned long)addr);
666 }
667 
668 /*
669  * Read from ELF header
670  */
671 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
672 {
673 	void *src = (void *)(unsigned long)*ppos;
674 
675 	memcpy(buf, src, count);
676 	*ppos += count;
677 	return count;
678 }
679 
680 /*
681  * Read from ELF notes data
682  */
683 ssize_t elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
684 {
685 	void *src = (void *)(unsigned long)*ppos;
686 
687 	memcpy(buf, src, count);
688 	*ppos += count;
689 	return count;
690 }
691