summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/crash.c
blob: c92d88680dbf16ba25826fb7d26b48bcfb72c695 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Architecture specific (i386/x86_64) functions for kexec based crash dumps.
 *
 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
 *
 * Copyright (C) IBM Corporation, 2004. All rights reserved.
 * Copyright (C) Red Hat Inc., 2014. All rights reserved.
 * Authors:
 *      Vivek Goyal <vgoyal@redhat.com>
 *
 */

#define pr_fmt(fmt)	"kexec: " fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/memblock.h>

#include <asm/processor.h>
#include <asm/hardirq.h>
#include <asm/nmi.h>
#include <asm/hw_irq.h>
#include <asm/apic.h>
#include <asm/e820/types.h>
#include <asm/io_apic.h>
#include <asm/hpet.h>
#include <linux/kdebug.h>
#include <asm/cpu.h>
#include <asm/reboot.h>
#include <asm/intel_pt.h>
#include <asm/crash.h>
#include <asm/cmdline.h>

/* Used while preparing memory map entries for second kernel */
struct crash_memmap_data {
	struct boot_params *params;
	/* Type of memory */
	unsigned int type;
};

#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)

static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
{
	crash_save_cpu(regs, cpu);

	/*
	 * Disable Intel PT to stop its logging
	 */
	cpu_emergency_stop_pt();

	disable_local_APIC();
}

void kdump_nmi_shootdown_cpus(void)
{
	nmi_shootdown_cpus(kdump_nmi_callback);

	disable_local_APIC();
}

/* Override the weak function in kernel/panic.c */
void crash_smp_send_stop(void)
{
	static int cpus_stopped;

	if (cpus_stopped)
		return;

	if (smp_ops.crash_stop_other_cpus)
		smp_ops.crash_stop_other_cpus();
	else
		smp_send_stop();

	cpus_stopped = 1;
}

#else
void crash_smp_send_stop(void)
{
	/* There are no cpus to shootdown */
}
#endif

void native_machine_crash_shutdown(struct pt_regs *regs)
{
	/* This function is only called after the system
	 * has panicked or is otherwise in a critical state.
	 * The minimum amount of code to allow a kexec'd kernel
	 * to run successfully needs to happen here.
	 *
	 * In practice this means shooting down the other cpus in
	 * an SMP system.
	 */
	/* The kernel is broken so disable interrupts */
	local_irq_disable();

	crash_smp_send_stop();

	cpu_emergency_disable_virtualization();

	/*
	 * Disable Intel PT to stop its logging
	 */
	cpu_emergency_stop_pt();

#ifdef CONFIG_X86_IO_APIC
	/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
	ioapic_zap_locks();
	clear_IO_APIC();
#endif
	lapic_shutdown();
	restore_boot_irq_mode();
#ifdef CONFIG_HPET_TIMER
	hpet_disable();
#endif
	crash_save_cpu(regs, safe_smp_processor_id());
}

#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)
static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
{
	unsigned int *nr_ranges = arg;

	(*nr_ranges)++;
	return 0;
}

/* Gather all the required information to prepare elf headers for ram regions */
static struct crash_mem *fill_up_crash_elf_data(void)
{
	unsigned int nr_ranges = 0;
	struct crash_mem *cmem;

	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
	if (!nr_ranges)
		return NULL;

	/*
	 * Exclusion of crash region and/or crashk_low_res may cause
	 * another range split. So add extra two slots here.
	 */
	nr_ranges += 2;
	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
	if (!cmem)
		return NULL;

	cmem->max_nr_ranges = nr_ranges;
	cmem->nr_ranges = 0;

	return cmem;
}

/*
 * Look for any unwanted ranges between mstart, mend and remove them. This
 * might lead to split and split ranges are put in cmem->ranges[] array
 */
static int elf_header_exclude_ranges(struct crash_mem *cmem)
{
	int ret = 0;

	/* Exclude the low 1M because it is always reserved */
	ret = crash_exclude_mem_range(cmem, 0, (1<<20)-1);
	if (ret)
		return ret;

	/* Exclude crashkernel region */
	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
	if (ret)
		return ret;

	if (crashk_low_res.end)
		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
					      crashk_low_res.end);

	return ret;
}

static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
	struct crash_mem *cmem = arg;

	cmem->ranges[cmem->nr_ranges].start = res->start;
	cmem->ranges[cmem->nr_ranges].end = res->end;
	cmem->nr_ranges++;

	return 0;
}

/* Prepare elf headers. Return addr and size */
static int prepare_elf_headers(struct kimage *image, void **addr,
					unsigned long *sz, unsigned long *nr_mem_ranges)
{
	struct crash_mem *cmem;
	int ret;

	cmem = fill_up_crash_elf_data();
	if (!cmem)
		return -ENOMEM;

	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
	if (ret)
		goto out;

	/* Exclude unwanted mem ranges */
	ret = elf_header_exclude_ranges(cmem);
	if (ret)
		goto out;

	/* Return the computed number of memory ranges, for hotplug usage */
	*nr_mem_ranges = cmem->nr_ranges;

	/* By default prepare 64bit headers */
	ret =  crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);

out:
	vfree(cmem);
	return ret;
}
#endif

#ifdef CONFIG_KEXEC_FILE
static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
{
	unsigned int nr_e820_entries;

	nr_e820_entries = params->e820_entries;
	if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
		return 1;

	memcpy(&params->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
	params->e820_entries++;
	return 0;
}

static int memmap_entry_callback(struct resource *res, void *arg)
{
	struct crash_memmap_data *cmd = arg;
	struct boot_params *params = cmd->params;
	struct e820_entry ei;

	ei.addr = res->start;
	ei.size = resource_size(res);
	ei.type = cmd->type;
	add_e820_entry(params, &ei);

	return 0;
}

static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
				 unsigned long long mstart,
				 unsigned long long mend)
{
	unsigned long start, end;

	cmem->ranges[0].start = mstart;
	cmem->ranges[0].end = mend;
	cmem->nr_ranges = 1;

	/* Exclude elf header region */
	start = image->elf_load_addr;
	end = start + image->elf_headers_sz - 1;
	return crash_exclude_mem_range(cmem, start, end);
}

/* Prepare memory map for crash dump kernel */
int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
{
	int i, ret = 0;
	unsigned long flags;
	struct e820_entry ei;
	struct crash_memmap_data cmd;
	struct crash_mem *cmem;

	cmem = vzalloc(struct_size(cmem, ranges, 1));
	if (!cmem)
		return -ENOMEM;

	memset(&cmd, 0, sizeof(struct crash_memmap_data));
	cmd.params = params;

	/* Add the low 1M */
	cmd.type = E820_TYPE_RAM;
	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
	walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
			    memmap_entry_callback);

	/* Add ACPI tables */
	cmd.type = E820_TYPE_ACPI;
	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
	walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
			    memmap_entry_callback);

	/* Add ACPI Non-volatile Storage */
	cmd.type = E820_TYPE_NVS;
	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
			    memmap_entry_callback);

	/* Add e820 reserved ranges */
	cmd.type = E820_TYPE_RESERVED;
	flags = IORESOURCE_MEM;
	walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
			    memmap_entry_callback);

	/* Add crashk_low_res region */
	if (crashk_low_res.end) {
		ei.addr = crashk_low_res.start;
		ei.size = resource_size(&crashk_low_res);
		ei.type = E820_TYPE_RAM;
		add_e820_entry(params, &ei);
	}

	/* Exclude some ranges from crashk_res and add rest to memmap */
	ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
	if (ret)
		goto out;

	for (i = 0; i < cmem->nr_ranges; i++) {
		ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;

		/* If entry is less than a page, skip it */
		if (ei.size < PAGE_SIZE)
			continue;
		ei.addr = cmem->ranges[i].start;
		ei.type = E820_TYPE_RAM;
		add_e820_entry(params, &ei);
	}

out:
	vfree(cmem);
	return ret;
}

int crash_load_segments(struct kimage *image)
{
	int ret;
	unsigned long pnum = 0;
	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
				  .buf_max = ULONG_MAX, .top_down = false };

	/* Prepare elf headers and add a segment */
	ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz, &pnum);
	if (ret)
		return ret;

	image->elf_headers	= kbuf.buffer;
	image->elf_headers_sz	= kbuf.bufsz;
	kbuf.memsz		= kbuf.bufsz;

#ifdef CONFIG_CRASH_HOTPLUG
	/*
	 * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map,
	 * maximum CPUs and maximum memory ranges.
	 */
	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
		pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES;
	else
		pnum += 2 + CONFIG_NR_CPUS_DEFAULT;

	if (pnum < (unsigned long)PN_XNUM) {
		kbuf.memsz = pnum * sizeof(Elf64_Phdr);
		kbuf.memsz += sizeof(Elf64_Ehdr);

		image->elfcorehdr_index = image->nr_segments;

		/* Mark as usable to crash kernel, else crash kernel fails on boot */
		image->elf_headers_sz = kbuf.memsz;
	} else {
		pr_err("number of Phdrs %lu exceeds max\n", pnum);
	}
#endif

	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
	ret = kexec_add_buffer(&kbuf);
	if (ret)
		return ret;
	image->elf_load_addr = kbuf.mem;
	pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
		 image->elf_load_addr, kbuf.bufsz, kbuf.memsz);

	return ret;
}
#endif /* CONFIG_KEXEC_FILE */

#ifdef CONFIG_CRASH_HOTPLUG

#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt

/* These functions provide the value for the sysfs crash_hotplug nodes */
#ifdef CONFIG_HOTPLUG_CPU
int arch_crash_hotplug_cpu_support(void)
{
	return crash_check_update_elfcorehdr();
}
#endif

#ifdef CONFIG_MEMORY_HOTPLUG
int arch_crash_hotplug_memory_support(void)
{
	return crash_check_update_elfcorehdr();
}
#endif

unsigned int arch_crash_get_elfcorehdr_size(void)
{
	unsigned int sz;

	/* kernel_map, VMCOREINFO and maximum CPUs */
	sz = 2 + CONFIG_NR_CPUS_DEFAULT;
	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
		sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
	sz *= sizeof(Elf64_Phdr);
	return sz;
}

/**
 * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
 * @image: a pointer to kexec_crash_image
 *
 * Prepare the new elfcorehdr and replace the existing elfcorehdr.
 */
void arch_crash_handle_hotplug_event(struct kimage *image)
{
	void *elfbuf = NULL, *old_elfcorehdr;
	unsigned long nr_mem_ranges;
	unsigned long mem, memsz;
	unsigned long elfsz = 0;

	/*
	 * As crash_prepare_elf64_headers() has already described all
	 * possible CPUs, there is no need to update the elfcorehdr
	 * for additional CPU changes.
	 */
	if ((image->file_mode || image->elfcorehdr_updated) &&
		((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) ||
		(image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU)))
		return;

	/*
	 * Create the new elfcorehdr reflecting the changes to CPU and/or
	 * memory resources.
	 */
	if (prepare_elf_headers(image, &elfbuf, &elfsz, &nr_mem_ranges)) {
		pr_err("unable to create new elfcorehdr");
		goto out;
	}

	/*
	 * Obtain address and size of the elfcorehdr segment, and
	 * check it against the new elfcorehdr buffer.
	 */
	mem = image->segment[image->elfcorehdr_index].mem;
	memsz = image->segment[image->elfcorehdr_index].memsz;
	if (elfsz > memsz) {
		pr_err("update elfcorehdr elfsz %lu > memsz %lu",
			elfsz, memsz);
		goto out;
	}

	/*
	 * Copy new elfcorehdr over the old elfcorehdr at destination.
	 */
	old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
	if (!old_elfcorehdr) {
		pr_err("mapping elfcorehdr segment failed\n");
		goto out;
	}

	/*
	 * Temporarily invalidate the crash image while the
	 * elfcorehdr is updated.
	 */
	xchg(&kexec_crash_image, NULL);
	memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz);
	xchg(&kexec_crash_image, image);
	kunmap_local(old_elfcorehdr);
	pr_debug("updated elfcorehdr\n");

out:
	vfree(elfbuf);
}
#endif