aboutsummaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/hibernate.c
blob: 46a0b4d6e2519768eaa86bc141f75f2efa698550 (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
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
// SPDX-License-Identifier: GPL-2.0-only
/*:
 * Hibernate support specific for ARM64
 *
 * Derived from work on ARM hibernation support by:
 *
 * Ubuntu project, hibernation support for mach-dove
 * Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
 * Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
 *  https://lkml.org/lkml/2010/6/18/4
 *  https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/027422.html
 *  https://patchwork.kernel.org/patch/96442/
 *
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 */
#define pr_fmt(x) "hibernate: " x
#include <linux/cpu.h>
#include <linux/kvm_host.h>
#include <linux/pm.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/utsname.h>

#include <asm/barrier.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/daifflags.h>
#include <asm/irqflags.h>
#include <asm/kexec.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
#include <asm/mte.h>
#include <asm/sections.h>
#include <asm/smp.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include <asm/sysreg.h>
#include <asm/trans_pgd.h>
#include <asm/virt.h>

/*
 * Hibernate core relies on this value being 0 on resume, and marks it
 * __nosavedata assuming it will keep the resume kernel's '0' value. This
 * doesn't happen with either KASLR.
 *
 * defined as "__visible int in_suspend __nosavedata" in
 * kernel/power/hibernate.c
 */
extern int in_suspend;

/* Do we need to reset el2? */
#define el2_reset_needed() (is_hyp_mode_available() && !is_kernel_in_hyp_mode())

/* temporary el2 vectors in the __hibernate_exit_text section. */
extern char hibernate_el2_vectors[];

/* hyp-stub vectors, used to restore el2 during resume from hibernate. */
extern char __hyp_stub_vectors[];

/*
 * The logical cpu number we should resume on, initialised to a non-cpu
 * number.
 */
static int sleep_cpu = -EINVAL;

/*
 * Values that may not change over hibernate/resume. We put the build number
 * and date in here so that we guarantee not to resume with a different
 * kernel.
 */
struct arch_hibernate_hdr_invariants {
	char		uts_version[__NEW_UTS_LEN + 1];
};

/* These values need to be know across a hibernate/restore. */
static struct arch_hibernate_hdr {
	struct arch_hibernate_hdr_invariants invariants;

	/* These are needed to find the relocated kernel if built with kaslr */
	phys_addr_t	ttbr1_el1;
	void		(*reenter_kernel)(void);

	/*
	 * We need to know where the __hyp_stub_vectors are after restore to
	 * re-configure el2.
	 */
	phys_addr_t	__hyp_stub_vectors;

	u64		sleep_cpu_mpidr;
} resume_hdr;

static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
{
	memset(i, 0, sizeof(*i));
	memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
}

int pfn_is_nosave(unsigned long pfn)
{
	unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
	unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);

	return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
		crash_is_nosave(pfn);
}

void notrace save_processor_state(void)
{
	WARN_ON(num_online_cpus() != 1);
}

void notrace restore_processor_state(void)
{
}

int arch_hibernation_header_save(void *addr, unsigned int max_size)
{
	struct arch_hibernate_hdr *hdr = addr;

	if (max_size < sizeof(*hdr))
		return -EOVERFLOW;

	arch_hdr_invariants(&hdr->invariants);
	hdr->ttbr1_el1		= __pa_symbol(swapper_pg_dir);
	hdr->reenter_kernel	= _cpu_resume;

	/* We can't use __hyp_get_vectors() because kvm may still be loaded */
	if (el2_reset_needed())
		hdr->__hyp_stub_vectors = __pa_symbol(__hyp_stub_vectors);
	else
		hdr->__hyp_stub_vectors = 0;

	/* Save the mpidr of the cpu we called cpu_suspend() on... */
	if (sleep_cpu < 0) {
		pr_err("Failing to hibernate on an unknown CPU.\n");
		return -ENODEV;
	}
	hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
	pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
		hdr->sleep_cpu_mpidr);

	return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_save);

int arch_hibernation_header_restore(void *addr)
{
	int ret;
	struct arch_hibernate_hdr_invariants invariants;
	struct arch_hibernate_hdr *hdr = addr;

	arch_hdr_invariants(&invariants);
	if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
		pr_crit("Hibernate image not generated by this kernel!\n");
		return -EINVAL;
	}

	sleep_cpu = get_logical_index(hdr->sleep_cpu_mpidr);
	pr_info("Hibernated on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
		hdr->sleep_cpu_mpidr);
	if (sleep_cpu < 0) {
		pr_crit("Hibernated on a CPU not known to this kernel!\n");
		sleep_cpu = -EINVAL;
		return -EINVAL;
	}

	ret = bringup_hibernate_cpu(sleep_cpu);
	if (ret) {
		sleep_cpu = -EINVAL;
		return ret;
	}

	resume_hdr = *hdr;

	return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_restore);

static void *hibernate_page_alloc(void *arg)
{
	return (void *)get_safe_page((__force gfp_t)(unsigned long)arg);
}

/*
 * Copies length bytes, starting at src_start into an new page,
 * perform cache maintenance, then maps it at the specified address low
 * address as executable.
 *
 * This is used by hibernate to copy the code it needs to execute when
 * overwriting the kernel text. This function generates a new set of page
 * tables, which it loads into ttbr0.
 *
 * Length is provided as we probably only want 4K of data, even on a 64K
 * page system.
 */
static int create_safe_exec_page(void *src_start, size_t length,
				 phys_addr_t *phys_dst_addr)
{
	struct trans_pgd_info trans_info = {
		.trans_alloc_page	= hibernate_page_alloc,
		.trans_alloc_arg	= (__force void *)GFP_ATOMIC,
	};

	void *page = (void *)get_safe_page(GFP_ATOMIC);
	phys_addr_t trans_ttbr0;
	unsigned long t0sz;
	int rc;

	if (!page)
		return -ENOMEM;

	memcpy(page, src_start, length);
	caches_clean_inval_pou((unsigned long)page, (unsigned long)page + length);
	rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
	if (rc)
		return rc;

	/*
	 * Load our new page tables. A strict BBM approach requires that we
	 * ensure that TLBs are free of any entries that may overlap with the
	 * global mappings we are about to install.
	 *
	 * For a real hibernate/resume cycle TTBR0 currently points to a zero
	 * page, but TLBs may contain stale ASID-tagged entries (e.g. for EFI
	 * runtime services), while for a userspace-driven test_resume cycle it
	 * points to userspace page tables (and we must point it at a zero page
	 * ourselves).
	 *
	 * We change T0SZ as part of installing the idmap. This is undone by
	 * cpu_uninstall_idmap() in __cpu_suspend_exit().
	 */
	cpu_set_reserved_ttbr0();
	local_flush_tlb_all();
	__cpu_set_tcr_t0sz(t0sz);
	write_sysreg(trans_ttbr0, ttbr0_el1);
	isb();

	*phys_dst_addr = virt_to_phys(page);

	return 0;
}

#ifdef CONFIG_ARM64_MTE

static DEFINE_XARRAY(mte_pages);

static int save_tags(struct page *page, unsigned long pfn)
{
	void *tag_storage, *ret;

	tag_storage = mte_allocate_tag_storage();
	if (!tag_storage)
		return -ENOMEM;

	mte_save_page_tags(page_address(page), tag_storage);

	ret = xa_store(&mte_pages, pfn, tag_storage, GFP_KERNEL);
	if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
		mte_free_tag_storage(tag_storage);
		return xa_err(ret);
	} else if (WARN(ret, "swsusp: %s: Duplicate entry", __func__)) {
		mte_free_tag_storage(ret);
	}

	return 0;
}

static void swsusp_mte_free_storage(void)
{
	XA_STATE(xa_state, &mte_pages, 0);
	void *tags;

	xa_lock(&mte_pages);
	xas_for_each(&xa_state, tags, ULONG_MAX) {
		mte_free_tag_storage(tags);
	}
	xa_unlock(&mte_pages);

	xa_destroy(&mte_pages);
}

static int swsusp_mte_save_tags(void)
{
	struct zone *zone;
	unsigned long pfn, max_zone_pfn;
	int ret = 0;
	int n = 0;

	if (!system_supports_mte())
		return 0;

	for_each_populated_zone(zone) {
		max_zone_pfn = zone_end_pfn(zone);
		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
			struct page *page = pfn_to_online_page(pfn);

			if (!page)
				continue;

			if (!test_bit(PG_mte_tagged, &page->flags))
				continue;

			ret = save_tags(page, pfn);
			if (ret) {
				swsusp_mte_free_storage();
				goto out;
			}

			n++;
		}
	}
	pr_info("Saved %d MTE pages\n", n);

out:
	return ret;
}

static void swsusp_mte_restore_tags(void)
{
	XA_STATE(xa_state, &mte_pages, 0);
	int n = 0;
	void *tags;

	xa_lock(&mte_pages);
	xas_for_each(&xa_state, tags, ULONG_MAX) {
		unsigned long pfn = xa_state.xa_index;
		struct page *page = pfn_to_online_page(pfn);

		/*
		 * It is not required to invoke page_kasan_tag_reset(page)
		 * at this point since the tags stored in page->flags are
		 * already restored.
		 */
		mte_restore_page_tags(page_address(page), tags);

		mte_free_tag_storage(tags);
		n++;
	}
	xa_unlock(&mte_pages);

	pr_info("Restored %d MTE pages\n", n);

	xa_destroy(&mte_pages);
}

#else	/* CONFIG_ARM64_MTE */

static int swsusp_mte_save_tags(void)
{
	return 0;
}

static void swsusp_mte_restore_tags(void)
{
}

#endif	/* CONFIG_ARM64_MTE */

int swsusp_arch_suspend(void)
{
	int ret = 0;
	unsigned long flags;
	struct sleep_stack_data state;

	if (cpus_are_stuck_in_kernel()) {
		pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
		return -EBUSY;
	}

	flags = local_daif_save();

	if (__cpu_suspend_enter(&state)) {
		/* make the crash dump kernel image visible/saveable */
		crash_prepare_suspend();

		ret = swsusp_mte_save_tags();
		if (ret)
			return ret;

		sleep_cpu = smp_processor_id();
		ret = swsusp_save();
	} else {
		/* Clean kernel core startup/idle code to PoC*/
		dcache_clean_inval_poc((unsigned long)__mmuoff_data_start,
				    (unsigned long)__mmuoff_data_end);
		dcache_clean_inval_poc((unsigned long)__idmap_text_start,
				    (unsigned long)__idmap_text_end);

		/* Clean kvm setup code to PoC? */
		if (el2_reset_needed()) {
			dcache_clean_inval_poc(
				(unsigned long)__hyp_idmap_text_start,
				(unsigned long)__hyp_idmap_text_end);
			dcache_clean_inval_poc((unsigned long)__hyp_text_start,
					    (unsigned long)__hyp_text_end);
		}

		swsusp_mte_restore_tags();

		/* make the crash dump kernel image protected again */
		crash_post_resume();

		/*
		 * Tell the hibernation core that we've just restored
		 * the memory
		 */
		in_suspend = 0;

		sleep_cpu = -EINVAL;
		__cpu_suspend_exit();

		/*
		 * Just in case the boot kernel did turn the SSBD
		 * mitigation off behind our back, let's set the state
		 * to what we expect it to be.
		 */
		spectre_v4_enable_mitigation(NULL);
	}

	local_daif_restore(flags);

	return ret;
}

/*
 * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
 *
 * Memory allocated by get_safe_page() will be dealt with by the hibernate code,
 * we don't need to free it here.
 */
int swsusp_arch_resume(void)
{
	int rc;
	void *zero_page;
	size_t exit_size;
	pgd_t *tmp_pg_dir;
	void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
					  void *, phys_addr_t, phys_addr_t);
	struct trans_pgd_info trans_info = {
		.trans_alloc_page	= hibernate_page_alloc,
		.trans_alloc_arg	= (void *)GFP_ATOMIC,
	};

	/*
	 * Restoring the memory image will overwrite the ttbr1 page tables.
	 * Create a second copy of just the linear map, and use this when
	 * restoring.
	 */
	rc = trans_pgd_create_copy(&trans_info, &tmp_pg_dir, PAGE_OFFSET,
				   PAGE_END);
	if (rc)
		return rc;

	/*
	 * We need a zero page that is zero before & after resume in order to
	 * to break before make on the ttbr1 page tables.
	 */
	zero_page = (void *)get_safe_page(GFP_ATOMIC);
	if (!zero_page) {
		pr_err("Failed to allocate zero page.\n");
		return -ENOMEM;
	}

	exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
	/*
	 * Copy swsusp_arch_suspend_exit() to a safe page. This will generate
	 * a new set of ttbr0 page tables and load them.
	 */
	rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
				   (phys_addr_t *)&hibernate_exit);
	if (rc) {
		pr_err("Failed to create safe executable page for hibernate_exit code.\n");
		return rc;
	}

	/*
	 * The hibernate exit text contains a set of el2 vectors, that will
	 * be executed at el2 with the mmu off in order to reload hyp-stub.
	 */
	dcache_clean_inval_poc((unsigned long)hibernate_exit,
			    (unsigned long)hibernate_exit + exit_size);

	/*
	 * KASLR will cause the el2 vectors to be in a different location in
	 * the resumed kernel. Load hibernate's temporary copy into el2.
	 *
	 * We can skip this step if we booted at EL1, or are running with VHE.
	 */
	if (el2_reset_needed()) {
		phys_addr_t el2_vectors = (phys_addr_t)hibernate_exit;
		el2_vectors += hibernate_el2_vectors -
			       __hibernate_exit_text_start;     /* offset */

		__hyp_set_vectors(el2_vectors);
	}

	hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
		       resume_hdr.reenter_kernel, restore_pblist,
		       resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));

	return 0;
}

int hibernate_resume_nonboot_cpu_disable(void)
{
	if (sleep_cpu < 0) {
		pr_err("Failing to resume from hibernate on an unknown CPU.\n");
		return -ENODEV;
	}

	return freeze_secondary_cpus(sleep_cpu);
}