1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Architecture specific (i386/x86_64) functions for kexec based crash dumps.
4 *
5 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
6 *
7 * Copyright (C) IBM Corporation, 2004. All rights reserved.
8 * Copyright (C) Red Hat Inc., 2014. All rights reserved.
9 * Authors:
10 * Vivek Goyal <vgoyal@redhat.com>
11 *
12 */
13
14 #define pr_fmt(fmt) "kexec: " fmt
15
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/smp.h>
19 #include <linux/reboot.h>
20 #include <linux/kexec.h>
21 #include <linux/delay.h>
22 #include <linux/elf.h>
23 #include <linux/elfcore.h>
24 #include <linux/export.h>
25 #include <linux/slab.h>
26 #include <linux/vmalloc.h>
27 #include <linux/memblock.h>
28
29 #include <asm/bootparam.h>
30 #include <asm/processor.h>
31 #include <asm/hardirq.h>
32 #include <asm/nmi.h>
33 #include <asm/hw_irq.h>
34 #include <asm/apic.h>
35 #include <asm/e820/types.h>
36 #include <asm/io_apic.h>
37 #include <asm/hpet.h>
38 #include <linux/kdebug.h>
39 #include <asm/cpu.h>
40 #include <asm/reboot.h>
41 #include <asm/intel_pt.h>
42 #include <asm/crash.h>
43 #include <asm/cmdline.h>
44 #include <asm/sev.h>
45
46 /* Used while preparing memory map entries for second kernel */
47 struct crash_memmap_data {
48 struct boot_params *params;
49 /* Type of memory */
50 unsigned int type;
51 };
52
53 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
54
kdump_nmi_callback(int cpu,struct pt_regs * regs)55 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
56 {
57 crash_save_cpu(regs, cpu);
58
59 /*
60 * Disable Intel PT to stop its logging
61 */
62 cpu_emergency_stop_pt();
63
64 kdump_sev_callback();
65
66 disable_local_APIC();
67 }
68
kdump_nmi_shootdown_cpus(void)69 void kdump_nmi_shootdown_cpus(void)
70 {
71 nmi_shootdown_cpus(kdump_nmi_callback);
72
73 disable_local_APIC();
74 }
75
76 /* Override the weak function in kernel/panic.c */
crash_smp_send_stop(void)77 void crash_smp_send_stop(void)
78 {
79 static int cpus_stopped;
80
81 if (cpus_stopped)
82 return;
83
84 if (smp_ops.crash_stop_other_cpus)
85 smp_ops.crash_stop_other_cpus();
86 else
87 smp_send_stop();
88
89 cpus_stopped = 1;
90 }
91
92 #else
crash_smp_send_stop(void)93 void crash_smp_send_stop(void)
94 {
95 /* There are no cpus to shootdown */
96 }
97 #endif
98
native_machine_crash_shutdown(struct pt_regs * regs)99 void native_machine_crash_shutdown(struct pt_regs *regs)
100 {
101 /* This function is only called after the system
102 * has panicked or is otherwise in a critical state.
103 * The minimum amount of code to allow a kexec'd kernel
104 * to run successfully needs to happen here.
105 *
106 * In practice this means shooting down the other cpus in
107 * an SMP system.
108 */
109 /* The kernel is broken so disable interrupts */
110 local_irq_disable();
111
112 crash_smp_send_stop();
113
114 cpu_emergency_disable_virtualization();
115
116 /*
117 * Disable Intel PT to stop its logging
118 */
119 cpu_emergency_stop_pt();
120
121 #ifdef CONFIG_X86_IO_APIC
122 /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
123 ioapic_zap_locks();
124 clear_IO_APIC();
125 #endif
126 lapic_shutdown();
127 restore_boot_irq_mode();
128 #ifdef CONFIG_HPET_TIMER
129 hpet_disable();
130 #endif
131
132 /*
133 * Non-crash kexec calls enc_kexec_begin() while scheduling is still
134 * active. This allows the callback to wait until all in-flight
135 * shared<->private conversions are complete. In a crash scenario,
136 * enc_kexec_begin() gets called after all but one CPU have been shut
137 * down and interrupts have been disabled. This allows the callback to
138 * detect a race with the conversion and report it.
139 */
140 x86_platform.guest.enc_kexec_begin();
141 x86_platform.guest.enc_kexec_finish();
142
143 crash_save_cpu(regs, smp_processor_id());
144 }
145
146 #if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)
get_nr_ram_ranges_callback(struct resource * res,void * arg)147 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
148 {
149 unsigned int *nr_ranges = arg;
150
151 (*nr_ranges)++;
152 return 0;
153 }
154
155 /* Gather all the required information to prepare elf headers for ram regions */
fill_up_crash_elf_data(void)156 static struct crash_mem *fill_up_crash_elf_data(void)
157 {
158 unsigned int nr_ranges = 0;
159 struct crash_mem *cmem;
160
161 walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
162 if (!nr_ranges)
163 return NULL;
164
165 /*
166 * Exclusion of crash region and/or crashk_low_res may cause
167 * another range split. So add extra two slots here.
168 */
169 nr_ranges += 2;
170 cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
171 if (!cmem)
172 return NULL;
173
174 cmem->max_nr_ranges = nr_ranges;
175 cmem->nr_ranges = 0;
176
177 return cmem;
178 }
179
180 /*
181 * Look for any unwanted ranges between mstart, mend and remove them. This
182 * might lead to split and split ranges are put in cmem->ranges[] array
183 */
elf_header_exclude_ranges(struct crash_mem * cmem)184 static int elf_header_exclude_ranges(struct crash_mem *cmem)
185 {
186 int ret = 0;
187
188 /* Exclude the low 1M because it is always reserved */
189 ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
190 if (ret)
191 return ret;
192
193 /* Exclude crashkernel region */
194 ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
195 if (ret)
196 return ret;
197
198 if (crashk_low_res.end)
199 ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
200 crashk_low_res.end);
201
202 return ret;
203 }
204
prepare_elf64_ram_headers_callback(struct resource * res,void * arg)205 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
206 {
207 struct crash_mem *cmem = arg;
208
209 cmem->ranges[cmem->nr_ranges].start = res->start;
210 cmem->ranges[cmem->nr_ranges].end = res->end;
211 cmem->nr_ranges++;
212
213 return 0;
214 }
215
216 /* Prepare elf headers. Return addr and size */
prepare_elf_headers(void ** addr,unsigned long * sz,unsigned long * nr_mem_ranges)217 static int prepare_elf_headers(void **addr, unsigned long *sz,
218 unsigned long *nr_mem_ranges)
219 {
220 struct crash_mem *cmem;
221 int ret;
222
223 cmem = fill_up_crash_elf_data();
224 if (!cmem)
225 return -ENOMEM;
226
227 ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
228 if (ret)
229 goto out;
230
231 /* Exclude unwanted mem ranges */
232 ret = elf_header_exclude_ranges(cmem);
233 if (ret)
234 goto out;
235
236 /* Return the computed number of memory ranges, for hotplug usage */
237 *nr_mem_ranges = cmem->nr_ranges;
238
239 /* By default prepare 64bit headers */
240 ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
241
242 out:
243 vfree(cmem);
244 return ret;
245 }
246 #endif
247
248 #ifdef CONFIG_KEXEC_FILE
add_e820_entry(struct boot_params * params,struct e820_entry * entry)249 static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
250 {
251 unsigned int nr_e820_entries;
252
253 nr_e820_entries = params->e820_entries;
254 if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
255 return 1;
256
257 memcpy(¶ms->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
258 params->e820_entries++;
259 return 0;
260 }
261
memmap_entry_callback(struct resource * res,void * arg)262 static int memmap_entry_callback(struct resource *res, void *arg)
263 {
264 struct crash_memmap_data *cmd = arg;
265 struct boot_params *params = cmd->params;
266 struct e820_entry ei;
267
268 ei.addr = res->start;
269 ei.size = resource_size(res);
270 ei.type = cmd->type;
271 add_e820_entry(params, &ei);
272
273 return 0;
274 }
275
memmap_exclude_ranges(struct kimage * image,struct crash_mem * cmem,unsigned long long mstart,unsigned long long mend)276 static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
277 unsigned long long mstart,
278 unsigned long long mend)
279 {
280 unsigned long start, end;
281 int ret;
282
283 cmem->ranges[0].start = mstart;
284 cmem->ranges[0].end = mend;
285 cmem->nr_ranges = 1;
286
287 /* Exclude elf header region */
288 start = image->elf_load_addr;
289 end = start + image->elf_headers_sz - 1;
290 ret = crash_exclude_mem_range(cmem, start, end);
291
292 if (ret)
293 return ret;
294
295 /* Exclude dm crypt keys region */
296 if (image->dm_crypt_keys_addr) {
297 start = image->dm_crypt_keys_addr;
298 end = start + image->dm_crypt_keys_sz - 1;
299 return crash_exclude_mem_range(cmem, start, end);
300 }
301
302 return ret;
303 }
304
305 /* Prepare memory map for crash dump kernel */
crash_setup_memmap_entries(struct kimage * image,struct boot_params * params)306 int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
307 {
308 unsigned int nr_ranges = 0;
309 int i, ret = 0;
310 unsigned long flags;
311 struct e820_entry ei;
312 struct crash_memmap_data cmd;
313 struct crash_mem *cmem;
314
315 /*
316 * Using random kexec_buf for passing dm crypt keys may cause a range
317 * split. So use two slots here.
318 */
319 nr_ranges = 2;
320 cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
321 if (!cmem)
322 return -ENOMEM;
323
324 cmem->max_nr_ranges = nr_ranges;
325 cmem->nr_ranges = 0;
326
327 memset(&cmd, 0, sizeof(struct crash_memmap_data));
328 cmd.params = params;
329
330 /* Add the low 1M */
331 cmd.type = E820_TYPE_RAM;
332 flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
333 walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
334 memmap_entry_callback);
335
336 /* Add ACPI tables */
337 cmd.type = E820_TYPE_ACPI;
338 flags = IORESOURCE_MEM | IORESOURCE_BUSY;
339 walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
340 memmap_entry_callback);
341
342 /* Add ACPI Non-volatile Storage */
343 cmd.type = E820_TYPE_NVS;
344 walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
345 memmap_entry_callback);
346
347 /* Add e820 reserved ranges */
348 cmd.type = E820_TYPE_RESERVED;
349 flags = IORESOURCE_MEM;
350 walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
351 memmap_entry_callback);
352
353 /* Add crashk_low_res region */
354 if (crashk_low_res.end) {
355 ei.addr = crashk_low_res.start;
356 ei.size = resource_size(&crashk_low_res);
357 ei.type = E820_TYPE_RAM;
358 add_e820_entry(params, &ei);
359 }
360
361 /* Exclude some ranges from crashk_res and add rest to memmap */
362 ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
363 if (ret)
364 goto out;
365
366 for (i = 0; i < cmem->nr_ranges; i++) {
367 ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
368
369 /* If entry is less than a page, skip it */
370 if (ei.size < PAGE_SIZE)
371 continue;
372 ei.addr = cmem->ranges[i].start;
373 ei.type = E820_TYPE_RAM;
374 add_e820_entry(params, &ei);
375 }
376
377 out:
378 vfree(cmem);
379 return ret;
380 }
381
crash_load_segments(struct kimage * image)382 int crash_load_segments(struct kimage *image)
383 {
384 int ret;
385 unsigned long pnum = 0;
386 struct kexec_buf kbuf = { .image = image, .buf_min = 0,
387 .buf_max = ULONG_MAX, .top_down = false };
388
389 /* Prepare elf headers and add a segment */
390 ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
391 if (ret)
392 return ret;
393
394 image->elf_headers = kbuf.buffer;
395 image->elf_headers_sz = kbuf.bufsz;
396 kbuf.memsz = kbuf.bufsz;
397
398 #ifdef CONFIG_CRASH_HOTPLUG
399 /*
400 * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map,
401 * maximum CPUs and maximum memory ranges.
402 */
403 if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
404 pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES;
405 else
406 pnum += 2 + CONFIG_NR_CPUS_DEFAULT;
407
408 if (pnum < (unsigned long)PN_XNUM) {
409 kbuf.memsz = pnum * sizeof(Elf64_Phdr);
410 kbuf.memsz += sizeof(Elf64_Ehdr);
411
412 image->elfcorehdr_index = image->nr_segments;
413
414 /* Mark as usable to crash kernel, else crash kernel fails on boot */
415 image->elf_headers_sz = kbuf.memsz;
416 } else {
417 pr_err("number of Phdrs %lu exceeds max\n", pnum);
418 }
419 #endif
420
421 kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
422 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
423 ret = kexec_add_buffer(&kbuf);
424 if (ret)
425 return ret;
426 image->elf_load_addr = kbuf.mem;
427 kexec_dprintk("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
428 image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
429
430 return ret;
431 }
432 #endif /* CONFIG_KEXEC_FILE */
433
434 #ifdef CONFIG_CRASH_HOTPLUG
435
436 #undef pr_fmt
437 #define pr_fmt(fmt) "crash hp: " fmt
438
arch_crash_hotplug_support(struct kimage * image,unsigned long kexec_flags)439 int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
440 {
441
442 #ifdef CONFIG_KEXEC_FILE
443 if (image->file_mode)
444 return 1;
445 #endif
446 /*
447 * Initially, crash hotplug support for kexec_load was added
448 * with the KEXEC_UPDATE_ELFCOREHDR flag. Later, this
449 * functionality was expanded to accommodate multiple kexec
450 * segment updates, leading to the introduction of the
451 * KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag bit. Consequently,
452 * when the kexec tool sends either of these flags, it indicates
453 * that the required kexec segment (elfcorehdr) is excluded from
454 * the SHA calculation.
455 */
456 return (kexec_flags & KEXEC_UPDATE_ELFCOREHDR ||
457 kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT);
458 }
459
arch_crash_get_elfcorehdr_size(void)460 unsigned int arch_crash_get_elfcorehdr_size(void)
461 {
462 unsigned int sz;
463
464 /* kernel_map, VMCOREINFO and maximum CPUs */
465 sz = 2 + CONFIG_NR_CPUS_DEFAULT;
466 if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
467 sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
468 sz *= sizeof(Elf64_Phdr);
469 return sz;
470 }
471
472 /**
473 * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
474 * @image: a pointer to kexec_crash_image
475 * @arg: struct memory_notify handler for memory hotplug case and
476 * NULL for CPU hotplug case.
477 *
478 * Prepare the new elfcorehdr and replace the existing elfcorehdr.
479 */
arch_crash_handle_hotplug_event(struct kimage * image,void * arg)480 void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
481 {
482 void *elfbuf = NULL, *old_elfcorehdr;
483 unsigned long nr_mem_ranges;
484 unsigned long mem, memsz;
485 unsigned long elfsz = 0;
486
487 /*
488 * As crash_prepare_elf64_headers() has already described all
489 * possible CPUs, there is no need to update the elfcorehdr
490 * for additional CPU changes.
491 */
492 if ((image->file_mode || image->elfcorehdr_updated) &&
493 ((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) ||
494 (image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU)))
495 return;
496
497 /*
498 * Create the new elfcorehdr reflecting the changes to CPU and/or
499 * memory resources.
500 */
501 if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
502 pr_err("unable to create new elfcorehdr");
503 goto out;
504 }
505
506 /*
507 * Obtain address and size of the elfcorehdr segment, and
508 * check it against the new elfcorehdr buffer.
509 */
510 mem = image->segment[image->elfcorehdr_index].mem;
511 memsz = image->segment[image->elfcorehdr_index].memsz;
512 if (elfsz > memsz) {
513 pr_err("update elfcorehdr elfsz %lu > memsz %lu",
514 elfsz, memsz);
515 goto out;
516 }
517
518 /*
519 * Copy new elfcorehdr over the old elfcorehdr at destination.
520 */
521 old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
522 if (!old_elfcorehdr) {
523 pr_err("mapping elfcorehdr segment failed\n");
524 goto out;
525 }
526
527 /*
528 * Temporarily invalidate the crash image while the
529 * elfcorehdr is updated.
530 */
531 xchg(&kexec_crash_image, NULL);
532 memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz);
533 xchg(&kexec_crash_image, image);
534 kunmap_local(old_elfcorehdr);
535 pr_debug("updated elfcorehdr\n");
536
537 out:
538 vfree(elfbuf);
539 }
540 #endif
541