xref: /linux/arch/x86/kernel/crash.c (revision 5860800e8696d2cbbd1a0dd60b433549d176e668)
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/processor.h>
30 #include <asm/hardirq.h>
31 #include <asm/nmi.h>
32 #include <asm/hw_irq.h>
33 #include <asm/apic.h>
34 #include <asm/e820/types.h>
35 #include <asm/io_apic.h>
36 #include <asm/hpet.h>
37 #include <linux/kdebug.h>
38 #include <asm/cpu.h>
39 #include <asm/reboot.h>
40 #include <asm/virtext.h>
41 #include <asm/intel_pt.h>
42 #include <asm/crash.h>
43 #include <asm/cmdline.h>
44 
45 /* Used while preparing memory map entries for second kernel */
46 struct crash_memmap_data {
47 	struct boot_params *params;
48 	/* Type of memory */
49 	unsigned int type;
50 };
51 
52 /*
53  * This is used to VMCLEAR all VMCSs loaded on the
54  * processor. And when loading kvm_intel module, the
55  * callback function pointer will be assigned.
56  *
57  * protected by rcu.
58  */
59 crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
60 EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
61 
62 static inline void cpu_crash_vmclear_loaded_vmcss(void)
63 {
64 	crash_vmclear_fn *do_vmclear_operation = NULL;
65 
66 	rcu_read_lock();
67 	do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
68 	if (do_vmclear_operation)
69 		do_vmclear_operation();
70 	rcu_read_unlock();
71 }
72 
73 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
74 
75 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
76 {
77 	crash_save_cpu(regs, cpu);
78 
79 	/*
80 	 * VMCLEAR VMCSs loaded on all cpus if needed.
81 	 */
82 	cpu_crash_vmclear_loaded_vmcss();
83 
84 	/* Disable VMX or SVM if needed.
85 	 *
86 	 * We need to disable virtualization on all CPUs.
87 	 * Having VMX or SVM enabled on any CPU may break rebooting
88 	 * after the kdump kernel has finished its task.
89 	 */
90 	cpu_emergency_vmxoff();
91 	cpu_emergency_svm_disable();
92 
93 	/*
94 	 * Disable Intel PT to stop its logging
95 	 */
96 	cpu_emergency_stop_pt();
97 
98 	disable_local_APIC();
99 }
100 
101 void kdump_nmi_shootdown_cpus(void)
102 {
103 	nmi_shootdown_cpus(kdump_nmi_callback);
104 
105 	disable_local_APIC();
106 }
107 
108 /* Override the weak function in kernel/panic.c */
109 void crash_smp_send_stop(void)
110 {
111 	static int cpus_stopped;
112 
113 	if (cpus_stopped)
114 		return;
115 
116 	if (smp_ops.crash_stop_other_cpus)
117 		smp_ops.crash_stop_other_cpus();
118 	else
119 		smp_send_stop();
120 
121 	cpus_stopped = 1;
122 }
123 
124 #else
125 void crash_smp_send_stop(void)
126 {
127 	/* There are no cpus to shootdown */
128 }
129 #endif
130 
131 void native_machine_crash_shutdown(struct pt_regs *regs)
132 {
133 	/* This function is only called after the system
134 	 * has panicked or is otherwise in a critical state.
135 	 * The minimum amount of code to allow a kexec'd kernel
136 	 * to run successfully needs to happen here.
137 	 *
138 	 * In practice this means shooting down the other cpus in
139 	 * an SMP system.
140 	 */
141 	/* The kernel is broken so disable interrupts */
142 	local_irq_disable();
143 
144 	crash_smp_send_stop();
145 
146 	/*
147 	 * VMCLEAR VMCSs loaded on this cpu if needed.
148 	 */
149 	cpu_crash_vmclear_loaded_vmcss();
150 
151 	/* Booting kdump kernel with VMX or SVM enabled won't work,
152 	 * because (among other limitations) we can't disable paging
153 	 * with the virt flags.
154 	 */
155 	cpu_emergency_vmxoff();
156 	cpu_emergency_svm_disable();
157 
158 	/*
159 	 * Disable Intel PT to stop its logging
160 	 */
161 	cpu_emergency_stop_pt();
162 
163 #ifdef CONFIG_X86_IO_APIC
164 	/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
165 	ioapic_zap_locks();
166 	clear_IO_APIC();
167 #endif
168 	lapic_shutdown();
169 	restore_boot_irq_mode();
170 #ifdef CONFIG_HPET_TIMER
171 	hpet_disable();
172 #endif
173 	crash_save_cpu(regs, safe_smp_processor_id());
174 }
175 
176 #ifdef CONFIG_KEXEC_FILE
177 
178 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
179 {
180 	unsigned int *nr_ranges = arg;
181 
182 	(*nr_ranges)++;
183 	return 0;
184 }
185 
186 /* Gather all the required information to prepare elf headers for ram regions */
187 static struct crash_mem *fill_up_crash_elf_data(void)
188 {
189 	unsigned int nr_ranges = 0;
190 	struct crash_mem *cmem;
191 
192 	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
193 	if (!nr_ranges)
194 		return NULL;
195 
196 	/*
197 	 * Exclusion of crash region and/or crashk_low_res may cause
198 	 * another range split. So add extra two slots here.
199 	 */
200 	nr_ranges += 2;
201 	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
202 	if (!cmem)
203 		return NULL;
204 
205 	cmem->max_nr_ranges = nr_ranges;
206 	cmem->nr_ranges = 0;
207 
208 	return cmem;
209 }
210 
211 /*
212  * Look for any unwanted ranges between mstart, mend and remove them. This
213  * might lead to split and split ranges are put in cmem->ranges[] array
214  */
215 static int elf_header_exclude_ranges(struct crash_mem *cmem)
216 {
217 	int ret = 0;
218 
219 	/* Exclude the low 1M because it is always reserved */
220 	ret = crash_exclude_mem_range(cmem, 0, (1<<20)-1);
221 	if (ret)
222 		return ret;
223 
224 	/* Exclude crashkernel region */
225 	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
226 	if (ret)
227 		return ret;
228 
229 	if (crashk_low_res.end)
230 		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
231 					      crashk_low_res.end);
232 
233 	return ret;
234 }
235 
236 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
237 {
238 	struct crash_mem *cmem = arg;
239 
240 	cmem->ranges[cmem->nr_ranges].start = res->start;
241 	cmem->ranges[cmem->nr_ranges].end = res->end;
242 	cmem->nr_ranges++;
243 
244 	return 0;
245 }
246 
247 /* Prepare elf headers. Return addr and size */
248 static int prepare_elf_headers(struct kimage *image, void **addr,
249 					unsigned long *sz)
250 {
251 	struct crash_mem *cmem;
252 	int ret;
253 
254 	cmem = fill_up_crash_elf_data();
255 	if (!cmem)
256 		return -ENOMEM;
257 
258 	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
259 	if (ret)
260 		goto out;
261 
262 	/* Exclude unwanted mem ranges */
263 	ret = elf_header_exclude_ranges(cmem);
264 	if (ret)
265 		goto out;
266 
267 	/* By default prepare 64bit headers */
268 	ret =  crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
269 
270 out:
271 	vfree(cmem);
272 	return ret;
273 }
274 
275 static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
276 {
277 	unsigned int nr_e820_entries;
278 
279 	nr_e820_entries = params->e820_entries;
280 	if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
281 		return 1;
282 
283 	memcpy(&params->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
284 	params->e820_entries++;
285 	return 0;
286 }
287 
288 static int memmap_entry_callback(struct resource *res, void *arg)
289 {
290 	struct crash_memmap_data *cmd = arg;
291 	struct boot_params *params = cmd->params;
292 	struct e820_entry ei;
293 
294 	ei.addr = res->start;
295 	ei.size = resource_size(res);
296 	ei.type = cmd->type;
297 	add_e820_entry(params, &ei);
298 
299 	return 0;
300 }
301 
302 static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
303 				 unsigned long long mstart,
304 				 unsigned long long mend)
305 {
306 	unsigned long start, end;
307 
308 	cmem->ranges[0].start = mstart;
309 	cmem->ranges[0].end = mend;
310 	cmem->nr_ranges = 1;
311 
312 	/* Exclude elf header region */
313 	start = image->elf_load_addr;
314 	end = start + image->elf_headers_sz - 1;
315 	return crash_exclude_mem_range(cmem, start, end);
316 }
317 
318 /* Prepare memory map for crash dump kernel */
319 int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
320 {
321 	int i, ret = 0;
322 	unsigned long flags;
323 	struct e820_entry ei;
324 	struct crash_memmap_data cmd;
325 	struct crash_mem *cmem;
326 
327 	cmem = vzalloc(struct_size(cmem, ranges, 1));
328 	if (!cmem)
329 		return -ENOMEM;
330 
331 	memset(&cmd, 0, sizeof(struct crash_memmap_data));
332 	cmd.params = params;
333 
334 	/* Add the low 1M */
335 	cmd.type = E820_TYPE_RAM;
336 	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
337 	walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
338 			    memmap_entry_callback);
339 
340 	/* Add ACPI tables */
341 	cmd.type = E820_TYPE_ACPI;
342 	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
343 	walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
344 			    memmap_entry_callback);
345 
346 	/* Add ACPI Non-volatile Storage */
347 	cmd.type = E820_TYPE_NVS;
348 	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
349 			    memmap_entry_callback);
350 
351 	/* Add e820 reserved ranges */
352 	cmd.type = E820_TYPE_RESERVED;
353 	flags = IORESOURCE_MEM;
354 	walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
355 			    memmap_entry_callback);
356 
357 	/* Add crashk_low_res region */
358 	if (crashk_low_res.end) {
359 		ei.addr = crashk_low_res.start;
360 		ei.size = resource_size(&crashk_low_res);
361 		ei.type = E820_TYPE_RAM;
362 		add_e820_entry(params, &ei);
363 	}
364 
365 	/* Exclude some ranges from crashk_res and add rest to memmap */
366 	ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
367 	if (ret)
368 		goto out;
369 
370 	for (i = 0; i < cmem->nr_ranges; i++) {
371 		ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
372 
373 		/* If entry is less than a page, skip it */
374 		if (ei.size < PAGE_SIZE)
375 			continue;
376 		ei.addr = cmem->ranges[i].start;
377 		ei.type = E820_TYPE_RAM;
378 		add_e820_entry(params, &ei);
379 	}
380 
381 out:
382 	vfree(cmem);
383 	return ret;
384 }
385 
386 int crash_load_segments(struct kimage *image)
387 {
388 	int ret;
389 	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
390 				  .buf_max = ULONG_MAX, .top_down = false };
391 
392 	/* Prepare elf headers and add a segment */
393 	ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz);
394 	if (ret)
395 		return ret;
396 
397 	image->elf_headers = kbuf.buffer;
398 	image->elf_headers_sz = kbuf.bufsz;
399 
400 	kbuf.memsz = kbuf.bufsz;
401 	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
402 	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
403 	ret = kexec_add_buffer(&kbuf);
404 	if (ret) {
405 		vfree((void *)image->elf_headers);
406 		return ret;
407 	}
408 	image->elf_load_addr = kbuf.mem;
409 	pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
410 		 image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
411 
412 	return ret;
413 }
414 #endif /* CONFIG_KEXEC_FILE */
415