summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/hibernate.c
blob: d55a7b09959b4d3f725ee6400a21fbc963d31b61 (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
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
/*:
 * 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>
 *
 * License terms: GNU General Public License (GPL) version 2
 */
#define pr_fmt(x) "hibernate: " x
#include <linux/cpu.h>
#include <linux/kvm_host.h>
#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/utsname.h>
#include <linux/version.h>

#include <asm/barrier.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/irqflags.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/pgtable-hwdef.h>
#include <asm/sections.h>
#include <asm/smp.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include <asm/sysreg.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;

/* Find a symbols alias in the linear map */
#define LMADDR(x)	phys_to_virt(virt_to_phys(x))

/* 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 = virt_to_pfn(&__nosave_begin);
	unsigned long nosave_end_pfn = virt_to_pfn(&__nosave_end - 1);

	return (pfn >= nosave_begin_pfn) && (pfn <= nosave_end_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		= virt_to_phys(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 = virt_to_phys(__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 unkown 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;
	}
	if (!cpu_online(sleep_cpu)) {
		pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
		ret = cpu_up(sleep_cpu);
		if (ret) {
			pr_err("Failed to bring hibernate-CPU up!\n");
			sleep_cpu = -EINVAL;
			return ret;
		}
	}

	resume_hdr = *hdr;

	return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_restore);

/*
 * Copies length bytes, starting at src_start into an new page,
 * perform cache maintentance, 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,
				 unsigned long dst_addr,
				 phys_addr_t *phys_dst_addr,
				 void *(*allocator)(gfp_t mask),
				 gfp_t mask)
{
	int rc = 0;
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	unsigned long dst = (unsigned long)allocator(mask);

	if (!dst) {
		rc = -ENOMEM;
		goto out;
	}

	memcpy((void *)dst, src_start, length);
	flush_icache_range(dst, dst + length);

	pgd = pgd_offset_raw(allocator(mask), dst_addr);
	if (pgd_none(*pgd)) {
		pud = allocator(mask);
		if (!pud) {
			rc = -ENOMEM;
			goto out;
		}
		pgd_populate(&init_mm, pgd, pud);
	}

	pud = pud_offset(pgd, dst_addr);
	if (pud_none(*pud)) {
		pmd = allocator(mask);
		if (!pmd) {
			rc = -ENOMEM;
			goto out;
		}
		pud_populate(&init_mm, pud, pmd);
	}

	pmd = pmd_offset(pud, dst_addr);
	if (pmd_none(*pmd)) {
		pte = allocator(mask);
		if (!pte) {
			rc = -ENOMEM;
			goto out;
		}
		pmd_populate_kernel(&init_mm, pmd, pte);
	}

	pte = pte_offset_kernel(pmd, dst_addr);
	set_pte(pte, __pte(virt_to_phys((void *)dst) |
			 pgprot_val(PAGE_KERNEL_EXEC)));

	/*
	 * 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). Elsewhere we only (un)install the idmap with preemption
	 * disabled, so T0SZ should be as required regardless.
	 */
	cpu_set_reserved_ttbr0();
	local_flush_tlb_all();
	write_sysreg(virt_to_phys(pgd), ttbr0_el1);
	isb();

	*phys_dst_addr = virt_to_phys((void *)dst);

out:
	return rc;
}

#define dcache_clean_range(start, end)	__flush_dcache_area(start, (end - start))

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;
	}

	local_dbg_save(flags);

	if (__cpu_suspend_enter(&state)) {
		sleep_cpu = smp_processor_id();
		ret = swsusp_save();
	} else {
		/* Clean kernel core startup/idle code to PoC*/
		dcache_clean_range(__mmuoff_data_start, __mmuoff_data_end);
		dcache_clean_range(__idmap_text_start, __idmap_text_end);

		/* Clean kvm setup code to PoC? */
		if (el2_reset_needed())
			dcache_clean_range(__hyp_idmap_text_start, __hyp_idmap_text_end);

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

		sleep_cpu = -EINVAL;
		__cpu_suspend_exit();
	}

	local_dbg_restore(flags);

	return ret;
}

static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
{
	pte_t pte = *src_pte;

	if (pte_valid(pte)) {
		/*
		 * Resume will overwrite areas that may be marked
		 * read only (code, rodata). Clear the RDONLY bit from
		 * the temporary mappings we use during restore.
		 */
		set_pte(dst_pte, pte_clear_rdonly(pte));
	} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
		/*
		 * debug_pagealloc will removed the PTE_VALID bit if
		 * the page isn't in use by the resume kernel. It may have
		 * been in use by the original kernel, in which case we need
		 * to put it back in our copy to do the restore.
		 *
		 * Before marking this entry valid, check the pfn should
		 * be mapped.
		 */
		BUG_ON(!pfn_valid(pte_pfn(pte)));

		set_pte(dst_pte, pte_mkpresent(pte_clear_rdonly(pte)));
	}
}

static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
		    unsigned long end)
{
	pte_t *src_pte;
	pte_t *dst_pte;
	unsigned long addr = start;

	dst_pte = (pte_t *)get_safe_page(GFP_ATOMIC);
	if (!dst_pte)
		return -ENOMEM;
	pmd_populate_kernel(&init_mm, dst_pmd, dst_pte);
	dst_pte = pte_offset_kernel(dst_pmd, start);

	src_pte = pte_offset_kernel(src_pmd, start);
	do {
		_copy_pte(dst_pte, src_pte, addr);
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

	return 0;
}

static int copy_pmd(pud_t *dst_pud, pud_t *src_pud, unsigned long start,
		    unsigned long end)
{
	pmd_t *src_pmd;
	pmd_t *dst_pmd;
	unsigned long next;
	unsigned long addr = start;

	if (pud_none(*dst_pud)) {
		dst_pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
		if (!dst_pmd)
			return -ENOMEM;
		pud_populate(&init_mm, dst_pud, dst_pmd);
	}
	dst_pmd = pmd_offset(dst_pud, start);

	src_pmd = pmd_offset(src_pud, start);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none(*src_pmd))
			continue;
		if (pmd_table(*src_pmd)) {
			if (copy_pte(dst_pmd, src_pmd, addr, next))
				return -ENOMEM;
		} else {
			set_pmd(dst_pmd,
				__pmd(pmd_val(*src_pmd) & ~PMD_SECT_RDONLY));
		}
	} while (dst_pmd++, src_pmd++, addr = next, addr != end);

	return 0;
}

static int copy_pud(pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long start,
		    unsigned long end)
{
	pud_t *dst_pud;
	pud_t *src_pud;
	unsigned long next;
	unsigned long addr = start;

	if (pgd_none(*dst_pgd)) {
		dst_pud = (pud_t *)get_safe_page(GFP_ATOMIC);
		if (!dst_pud)
			return -ENOMEM;
		pgd_populate(&init_mm, dst_pgd, dst_pud);
	}
	dst_pud = pud_offset(dst_pgd, start);

	src_pud = pud_offset(src_pgd, start);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none(*src_pud))
			continue;
		if (pud_table(*(src_pud))) {
			if (copy_pmd(dst_pud, src_pud, addr, next))
				return -ENOMEM;
		} else {
			set_pud(dst_pud,
				__pud(pud_val(*src_pud) & ~PMD_SECT_RDONLY));
		}
	} while (dst_pud++, src_pud++, addr = next, addr != end);

	return 0;
}

static int copy_page_tables(pgd_t *dst_pgd, unsigned long start,
			    unsigned long end)
{
	unsigned long next;
	unsigned long addr = start;
	pgd_t *src_pgd = pgd_offset_k(start);

	dst_pgd = pgd_offset_raw(dst_pgd, start);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none(*src_pgd))
			continue;
		if (copy_pud(dst_pgd, src_pgd, addr, next))
			return -ENOMEM;
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);

	return 0;
}

/*
 * 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 = 0;
	void *zero_page;
	size_t exit_size;
	pgd_t *tmp_pg_dir;
	void *lm_restore_pblist;
	phys_addr_t phys_hibernate_exit;
	void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
					  void *, phys_addr_t, phys_addr_t);

	/*
	 * Restoring the memory image will overwrite the ttbr1 page tables.
	 * Create a second copy of just the linear map, and use this when
	 * restoring.
	 */
	tmp_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
	if (!tmp_pg_dir) {
		pr_err("Failed to allocate memory for temporary page tables.");
		rc = -ENOMEM;
		goto out;
	}
	rc = copy_page_tables(tmp_pg_dir, PAGE_OFFSET, 0);
	if (rc)
		goto out;

	/*
	 * Since we only copied the linear map, we need to find restore_pblist's
	 * linear map address.
	 */
	lm_restore_pblist = LMADDR(restore_pblist);

	/*
	 * 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.");
		rc = -ENOMEM;
		goto out;
	}

	/*
	 * Locate the exit code in the bottom-but-one page, so that *NULL
	 * still has disastrous affects.
	 */
	hibernate_exit = (void *)PAGE_SIZE;
	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,
				   (unsigned long)hibernate_exit,
				   &phys_hibernate_exit,
				   (void *)get_safe_page, GFP_ATOMIC);
	if (rc) {
		pr_err("Failed to create safe executable page for hibernate_exit code.");
		goto out;
	}

	/*
	 * 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.
	 */
	__flush_dcache_area(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_hibernate_exit;  /* base */
		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, lm_restore_pblist,
		       resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));

out:
	return rc;
}

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

	return freeze_secondary_cpus(sleep_cpu);
}