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	crash_save_cpu(regs, safe_smp_processor_id());
132}
133
134#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)
135static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
136{
137	unsigned int *nr_ranges = arg;
138
139	(*nr_ranges)++;
140	return 0;
141}
142
143/* Gather all the required information to prepare elf headers for ram regions */
144static struct crash_mem *fill_up_crash_elf_data(void)
145{
146	unsigned int nr_ranges = 0;
147	struct crash_mem *cmem;
148
149	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
150	if (!nr_ranges)
151		return NULL;
152
153	/*
154	 * Exclusion of crash region and/or crashk_low_res may cause
155	 * another range split. So add extra two slots here.
156	 */
157	nr_ranges += 2;
158	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
159	if (!cmem)
160		return NULL;
161
162	cmem->max_nr_ranges = nr_ranges;
163	cmem->nr_ranges = 0;
164
165	return cmem;
166}
167
168/*
169 * Look for any unwanted ranges between mstart, mend and remove them. This
170 * might lead to split and split ranges are put in cmem->ranges[] array
171 */
172static int elf_header_exclude_ranges(struct crash_mem *cmem)
173{
174	int ret = 0;
175
176	/* Exclude the low 1M because it is always reserved */
177	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
178	if (ret)
179		return ret;
180
181	/* Exclude crashkernel region */
182	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
183	if (ret)
184		return ret;
185
186	if (crashk_low_res.end)
187		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
188					      crashk_low_res.end);
189
190	return ret;
191}
192
193static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
194{
195	struct crash_mem *cmem = arg;
196
197	cmem->ranges[cmem->nr_ranges].start = res->start;
198	cmem->ranges[cmem->nr_ranges].end = res->end;
199	cmem->nr_ranges++;
200
201	return 0;
202}
203
204/* Prepare elf headers. Return addr and size */
205static int prepare_elf_headers(void **addr, unsigned long *sz,
206			       unsigned long *nr_mem_ranges)
207{
208	struct crash_mem *cmem;
209	int ret;
210
211	cmem = fill_up_crash_elf_data();
212	if (!cmem)
213		return -ENOMEM;
214
215	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
216	if (ret)
217		goto out;
218
219	/* Exclude unwanted mem ranges */
220	ret = elf_header_exclude_ranges(cmem);
221	if (ret)
222		goto out;
223
224	/* Return the computed number of memory ranges, for hotplug usage */
225	*nr_mem_ranges = cmem->nr_ranges;
226
227	/* By default prepare 64bit headers */
228	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
229
230out:
231	vfree(cmem);
232	return ret;
233}
234#endif
235
236#ifdef CONFIG_KEXEC_FILE
237static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
238{
239	unsigned int nr_e820_entries;
240
241	nr_e820_entries = params->e820_entries;
242	if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
243		return 1;
244
245	memcpy(&params->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
246	params->e820_entries++;
247	return 0;
248}
249
250static int memmap_entry_callback(struct resource *res, void *arg)
251{
252	struct crash_memmap_data *cmd = arg;
253	struct boot_params *params = cmd->params;
254	struct e820_entry ei;
255
256	ei.addr = res->start;
257	ei.size = resource_size(res);
258	ei.type = cmd->type;
259	add_e820_entry(params, &ei);
260
261	return 0;
262}
263
264static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
265				 unsigned long long mstart,
266				 unsigned long long mend)
267{
268	unsigned long start, end;
269
270	cmem->ranges[0].start = mstart;
271	cmem->ranges[0].end = mend;
272	cmem->nr_ranges = 1;
273
274	/* Exclude elf header region */
275	start = image->elf_load_addr;
276	end = start + image->elf_headers_sz - 1;
277	return crash_exclude_mem_range(cmem, start, end);
278}
279
280/* Prepare memory map for crash dump kernel */
281int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
282{
283	int i, ret = 0;
284	unsigned long flags;
285	struct e820_entry ei;
286	struct crash_memmap_data cmd;
287	struct crash_mem *cmem;
288
289	cmem = vzalloc(struct_size(cmem, ranges, 1));
290	if (!cmem)
291		return -ENOMEM;
292
293	memset(&cmd, 0, sizeof(struct crash_memmap_data));
294	cmd.params = params;
295
296	/* Add the low 1M */
297	cmd.type = E820_TYPE_RAM;
298	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
299	walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
300			    memmap_entry_callback);
301
302	/* Add ACPI tables */
303	cmd.type = E820_TYPE_ACPI;
304	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
305	walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
306			    memmap_entry_callback);
307
308	/* Add ACPI Non-volatile Storage */
309	cmd.type = E820_TYPE_NVS;
310	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
311			    memmap_entry_callback);
312
313	/* Add e820 reserved ranges */
314	cmd.type = E820_TYPE_RESERVED;
315	flags = IORESOURCE_MEM;
316	walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
317			    memmap_entry_callback);
318
319	/* Add crashk_low_res region */
320	if (crashk_low_res.end) {
321		ei.addr = crashk_low_res.start;
322		ei.size = resource_size(&crashk_low_res);
323		ei.type = E820_TYPE_RAM;
324		add_e820_entry(params, &ei);
325	}
326
327	/* Exclude some ranges from crashk_res and add rest to memmap */
328	ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
329	if (ret)
330		goto out;
331
332	for (i = 0; i < cmem->nr_ranges; i++) {
333		ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
334
335		/* If entry is less than a page, skip it */
336		if (ei.size < PAGE_SIZE)
337			continue;
338		ei.addr = cmem->ranges[i].start;
339		ei.type = E820_TYPE_RAM;
340		add_e820_entry(params, &ei);
341	}
342
343out:
344	vfree(cmem);
345	return ret;
346}
347
348int crash_load_segments(struct kimage *image)
349{
350	int ret;
351	unsigned long pnum = 0;
352	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
353				  .buf_max = ULONG_MAX, .top_down = false };
354
355	/* Prepare elf headers and add a segment */
356	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
357	if (ret)
358		return ret;
359
360	image->elf_headers	= kbuf.buffer;
361	image->elf_headers_sz	= kbuf.bufsz;
362	kbuf.memsz		= kbuf.bufsz;
363
364#ifdef CONFIG_CRASH_HOTPLUG
365	/*
366	 * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map,
367	 * maximum CPUs and maximum memory ranges.
368	 */
369	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
370		pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES;
371	else
372		pnum += 2 + CONFIG_NR_CPUS_DEFAULT;
373
374	if (pnum < (unsigned long)PN_XNUM) {
375		kbuf.memsz = pnum * sizeof(Elf64_Phdr);
376		kbuf.memsz += sizeof(Elf64_Ehdr);
377
378		image->elfcorehdr_index = image->nr_segments;
379
380		/* Mark as usable to crash kernel, else crash kernel fails on boot */
381		image->elf_headers_sz = kbuf.memsz;
382	} else {
383		pr_err("number of Phdrs %lu exceeds max\n", pnum);
384	}
385#endif
386
387	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
388	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
389	ret = kexec_add_buffer(&kbuf);
390	if (ret)
391		return ret;
392	image->elf_load_addr = kbuf.mem;
393	kexec_dprintk("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
394		      image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
395
396	return ret;
397}
398#endif /* CONFIG_KEXEC_FILE */
399
400#ifdef CONFIG_CRASH_HOTPLUG
401
402#undef pr_fmt
403#define pr_fmt(fmt) "crash hp: " fmt
404
405/* These functions provide the value for the sysfs crash_hotplug nodes */
406#ifdef CONFIG_HOTPLUG_CPU
407int arch_crash_hotplug_cpu_support(void)
408{
409	return crash_check_update_elfcorehdr();
410}
411#endif
412
413#ifdef CONFIG_MEMORY_HOTPLUG
414int arch_crash_hotplug_memory_support(void)
415{
416	return crash_check_update_elfcorehdr();
417}
418#endif
419
420unsigned int arch_crash_get_elfcorehdr_size(void)
421{
422	unsigned int sz;
423
424	/* kernel_map, VMCOREINFO and maximum CPUs */
425	sz = 2 + CONFIG_NR_CPUS_DEFAULT;
426	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
427		sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
428	sz *= sizeof(Elf64_Phdr);
429	return sz;
430}
431
432/**
433 * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
434 * @image: a pointer to kexec_crash_image
435 *
436 * Prepare the new elfcorehdr and replace the existing elfcorehdr.
437 */
438void arch_crash_handle_hotplug_event(struct kimage *image)
439{
440	void *elfbuf = NULL, *old_elfcorehdr;
441	unsigned long nr_mem_ranges;
442	unsigned long mem, memsz;
443	unsigned long elfsz = 0;
444
445	/*
446	 * As crash_prepare_elf64_headers() has already described all
447	 * possible CPUs, there is no need to update the elfcorehdr
448	 * for additional CPU changes.
449	 */
450	if ((image->file_mode || image->elfcorehdr_updated) &&
451		((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) ||
452		(image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU)))
453		return;
454
455	/*
456	 * Create the new elfcorehdr reflecting the changes to CPU and/or
457	 * memory resources.
458	 */
459	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
460		pr_err("unable to create new elfcorehdr");
461		goto out;
462	}
463
464	/*
465	 * Obtain address and size of the elfcorehdr segment, and
466	 * check it against the new elfcorehdr buffer.
467	 */
468	mem = image->segment[image->elfcorehdr_index].mem;
469	memsz = image->segment[image->elfcorehdr_index].memsz;
470	if (elfsz > memsz) {
471		pr_err("update elfcorehdr elfsz %lu > memsz %lu",
472			elfsz, memsz);
473		goto out;
474	}
475
476	/*
477	 * Copy new elfcorehdr over the old elfcorehdr at destination.
478	 */
479	old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
480	if (!old_elfcorehdr) {
481		pr_err("mapping elfcorehdr segment failed\n");
482		goto out;
483	}
484
485	/*
486	 * Temporarily invalidate the crash image while the
487	 * elfcorehdr is updated.
488	 */
489	xchg(&kexec_crash_image, NULL);
490	memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz);
491	xchg(&kexec_crash_image, image);
492	kunmap_local(old_elfcorehdr);
493	pr_debug("updated elfcorehdr\n");
494
495out:
496	vfree(elfbuf);
497}
498#endif
499