crash.c

  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 */
 47struct 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
 55static 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
 69void 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 */
 77void 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
 93void crash_smp_send_stop(void)
 94{
 95	/* There are no cpus to shootdown */
 96}
 97#endif
 98
 99void 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)
147static 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 */
156static 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, crashk_low_res and/or crashk_cma_ranges
167	 * may cause range splits. So add extra slots here.
168	 *
169	 * Exclusion of low 1M may not cause another range split, because the
170	 * range of exclude is [0, 1M] and the condition for splitting a new
171	 * region is that the start, end parameters are both in a certain
172	 * existing region in cmem and cannot be equal to existing region's
173	 * start or end. Obviously, the start of [0, 1M] cannot meet this
174	 * condition.
175	 *
176	 * But in order to lest the low 1M could be changed in the future,
177	 * (e.g. [start, 1M]), add a extra slot.
178	 */
179	nr_ranges += 3 + crashk_cma_cnt;
180	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
181	if (!cmem)
182		return NULL;
183
184	cmem->max_nr_ranges = nr_ranges;
185
186	return cmem;
187}
188
189/*
190 * Look for any unwanted ranges between mstart, mend and remove them. This
191 * might lead to split and split ranges are put in cmem->ranges[] array
192 */
193static int elf_header_exclude_ranges(struct crash_mem *cmem)
194{
195	int ret = 0;
196	int i;
197
198	/* Exclude the low 1M because it is always reserved */
199	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
200	if (ret)
201		return ret;
202
203	/* Exclude crashkernel region */
204	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
205	if (ret)
206		return ret;
207
208	if (crashk_low_res.end)
209		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
210					      crashk_low_res.end);
211	if (ret)
212		return ret;
213
214	for (i = 0; i < crashk_cma_cnt; ++i) {
215		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
216					      crashk_cma_ranges[i].end);
217		if (ret)
218			return ret;
219	}
220
221	return 0;
222}
223
224static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
225{
226	struct crash_mem *cmem = arg;
227
228	cmem->ranges[cmem->nr_ranges].start = res->start;
229	cmem->ranges[cmem->nr_ranges].end = res->end;
230	cmem->nr_ranges++;
231
232	return 0;
233}
234
235/* Prepare elf headers. Return addr and size */
236static int prepare_elf_headers(void **addr, unsigned long *sz,
237			       unsigned long *nr_mem_ranges)
238{
239	struct crash_mem *cmem;
240	int ret;
241
242	cmem = fill_up_crash_elf_data();
243	if (!cmem)
244		return -ENOMEM;
245
246	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
247	if (ret)
248		goto out;
249
250	/* Exclude unwanted mem ranges */
251	ret = elf_header_exclude_ranges(cmem);
252	if (ret)
253		goto out;
254
255	/* Return the computed number of memory ranges, for hotplug usage */
256	*nr_mem_ranges = cmem->nr_ranges;
257
258	/* By default prepare 64bit headers */
259	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
260
261out:
262	vfree(cmem);
263	return ret;
264}
265#endif
266
267#ifdef CONFIG_KEXEC_FILE
268static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
269{
270	unsigned int nr_e820_entries;
271
272	nr_e820_entries = params->e820_entries;
273	if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
274		return 1;
275
276	memcpy(&params->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
277	params->e820_entries++;
278	return 0;
279}
280
281static int memmap_entry_callback(struct resource *res, void *arg)
282{
283	struct crash_memmap_data *cmd = arg;
284	struct boot_params *params = cmd->params;
285	struct e820_entry ei;
286
287	ei.addr = res->start;
288	ei.size = resource_size(res);
289	ei.type = cmd->type;
290	add_e820_entry(params, &ei);
291
292	return 0;
293}
294
295static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
296				 unsigned long long mstart,
297				 unsigned long long mend)
298{
299	unsigned long start, end;
300	int ret;
301
302	cmem->ranges[0].start = mstart;
303	cmem->ranges[0].end = mend;
304	cmem->nr_ranges = 1;
305
306	/* Exclude elf header region */
307	start = image->elf_load_addr;
308	end = start + image->elf_headers_sz - 1;
309	ret = crash_exclude_mem_range(cmem, start, end);
310
311	if (ret)
312		return ret;
313
314	/* Exclude dm crypt keys region */
315	if (image->dm_crypt_keys_addr) {
316		start = image->dm_crypt_keys_addr;
317		end = start + image->dm_crypt_keys_sz - 1;
318		return crash_exclude_mem_range(cmem, start, end);
319	}
320
321	return ret;
322}
323
324/* Prepare memory map for crash dump kernel */
325int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
326{
327	unsigned int nr_ranges = 0;
328	int i, ret = 0;
329	unsigned long flags;
330	struct e820_entry ei;
331	struct crash_memmap_data cmd;
332	struct crash_mem *cmem;
333
334	/*
335	 * In the current x86 architecture code, the elfheader is always
336	 * allocated at crashk_res.start. But it depends on the allocation
337	 * position of elfheader in crashk_res. To avoid potential out of
338	 * bounds in future, add an extra slot.
339	 *
340	 * And using random kexec_buf for passing dm crypt keys may cause a
341	 * range split too, add another extra slot here.
342	 */
343	nr_ranges = 3;
344	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
345	if (!cmem)
346		return -ENOMEM;
347
348	cmem->max_nr_ranges = nr_ranges;
349
350	memset(&cmd, 0, sizeof(struct crash_memmap_data));
351	cmd.params = params;
352
353	/* Add the low 1M */
354	cmd.type = E820_TYPE_RAM;
355	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
356	walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
357			    memmap_entry_callback);
358
359	/* Add ACPI tables */
360	cmd.type = E820_TYPE_ACPI;
361	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
362	walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
363			    memmap_entry_callback);
364
365	/* Add ACPI Non-volatile Storage */
366	cmd.type = E820_TYPE_NVS;
367	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
368			    memmap_entry_callback);
369
370	/* Add e820 reserved ranges */
371	cmd.type = E820_TYPE_RESERVED;
372	flags = IORESOURCE_MEM;
373	walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
374			    memmap_entry_callback);
375
376	/* Add crashk_low_res region */
377	if (crashk_low_res.end) {
378		ei.addr = crashk_low_res.start;
379		ei.size = resource_size(&crashk_low_res);
380		ei.type = E820_TYPE_RAM;
381		add_e820_entry(params, &ei);
382	}
383
384	/* Exclude some ranges from crashk_res and add rest to memmap */
385	ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
386	if (ret)
387		goto out;
388
389	for (i = 0; i < cmem->nr_ranges; i++) {
390		ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
391
392		/* If entry is less than a page, skip it */
393		if (ei.size < PAGE_SIZE)
394			continue;
395		ei.addr = cmem->ranges[i].start;
396		ei.type = E820_TYPE_RAM;
397		add_e820_entry(params, &ei);
398	}
399
400	for (i = 0; i < crashk_cma_cnt; ++i) {
401		ei.addr = crashk_cma_ranges[i].start;
402		ei.size = crashk_cma_ranges[i].end -
403			  crashk_cma_ranges[i].start + 1;
404		ei.type = E820_TYPE_RAM;
405		add_e820_entry(params, &ei);
406	}
407
408out:
409	vfree(cmem);
410	return ret;
411}
412
413int crash_load_segments(struct kimage *image)
414{
415	int ret;
416	unsigned long pnum = 0;
417	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
418				  .buf_max = ULONG_MAX, .top_down = false };
419
420	/* Prepare elf headers and add a segment */
421	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
422	if (ret)
423		return ret;
424
425	image->elf_headers	= kbuf.buffer;
426	image->elf_headers_sz	= kbuf.bufsz;
427	kbuf.memsz		= kbuf.bufsz;
428
429#ifdef CONFIG_CRASH_HOTPLUG
430	/*
431	 * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map,
432	 * maximum CPUs and maximum memory ranges.
433	 */
434	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
435		pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES;
436	else
437		pnum += 2 + CONFIG_NR_CPUS_DEFAULT;
438
439	if (pnum < (unsigned long)PN_XNUM) {
440		kbuf.memsz = pnum * sizeof(Elf64_Phdr);
441		kbuf.memsz += sizeof(Elf64_Ehdr);
442
443		image->elfcorehdr_index = image->nr_segments;
444
445		/* Mark as usable to crash kernel, else crash kernel fails on boot */
446		image->elf_headers_sz = kbuf.memsz;
447	} else {
448		pr_err("number of Phdrs %lu exceeds max\n", pnum);
449	}
450#endif
451
452	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
453	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
454	ret = kexec_add_buffer(&kbuf);
455	if (ret)
456		return ret;
457	image->elf_load_addr = kbuf.mem;
458	kexec_dprintk("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
459		      image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
460
461	return ret;
462}
463#endif /* CONFIG_KEXEC_FILE */
464
465#ifdef CONFIG_CRASH_HOTPLUG
466
467#undef pr_fmt
468#define pr_fmt(fmt) "crash hp: " fmt
469
470int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
471{
472
473#ifdef CONFIG_KEXEC_FILE
474	if (image->file_mode)
475		return 1;
476#endif
477	/*
478	 * Initially, crash hotplug support for kexec_load was added
479	 * with the KEXEC_UPDATE_ELFCOREHDR flag. Later, this
480	 * functionality was expanded to accommodate multiple kexec
481	 * segment updates, leading to the introduction of the
482	 * KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag bit. Consequently,
483	 * when the kexec tool sends either of these flags, it indicates
484	 * that the required kexec segment (elfcorehdr) is excluded from
485	 * the SHA calculation.
486	 */
487	return (kexec_flags & KEXEC_UPDATE_ELFCOREHDR ||
488		kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT);
489}
490
491unsigned int arch_crash_get_elfcorehdr_size(void)
492{
493	unsigned int sz;
494
495	/* kernel_map, VMCOREINFO and maximum CPUs */
496	sz = 2 + CONFIG_NR_CPUS_DEFAULT;
497	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
498		sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
499	sz *= sizeof(Elf64_Phdr);
500	return sz;
501}
502
503/**
504 * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
505 * @image: a pointer to kexec_crash_image
506 * @arg: struct memory_notify handler for memory hotplug case and
507 *       NULL for CPU hotplug case.
508 *
509 * Prepare the new elfcorehdr and replace the existing elfcorehdr.
510 */
511void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
512{
513	void *elfbuf = NULL, *old_elfcorehdr;
514	unsigned long nr_mem_ranges;
515	unsigned long mem, memsz;
516	unsigned long elfsz = 0;
517
518	/*
519	 * As crash_prepare_elf64_headers() has already described all
520	 * possible CPUs, there is no need to update the elfcorehdr
521	 * for additional CPU changes.
522	 */
523	if ((image->file_mode || image->elfcorehdr_updated) &&
524		((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) ||
525		(image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU)))
526		return;
527
528	/*
529	 * Create the new elfcorehdr reflecting the changes to CPU and/or
530	 * memory resources.
531	 */
532	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
533		pr_err("unable to create new elfcorehdr");
534		goto out;
535	}
536
537	/*
538	 * Obtain address and size of the elfcorehdr segment, and
539	 * check it against the new elfcorehdr buffer.
540	 */
541	mem = image->segment[image->elfcorehdr_index].mem;
542	memsz = image->segment[image->elfcorehdr_index].memsz;
543	if (elfsz > memsz) {
544		pr_err("update elfcorehdr elfsz %lu > memsz %lu",
545			elfsz, memsz);
546		goto out;
547	}
548
549	/*
550	 * Copy new elfcorehdr over the old elfcorehdr at destination.
551	 */
552	old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
553	if (!old_elfcorehdr) {
554		pr_err("mapping elfcorehdr segment failed\n");
555		goto out;
556	}
557
558	/*
559	 * Temporarily invalidate the crash image while the
560	 * elfcorehdr is updated.
561	 */
562	xchg(&kexec_crash_image, NULL);
563	memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz);
564	xchg(&kexec_crash_image, image);
565	kunmap_local(old_elfcorehdr);
566	pr_debug("updated elfcorehdr\n");
567
568out:
569	vfree(elfbuf);
570}
571#endif