aboutsummaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/hibernate.c
blob: 7e16fb327644564c72cb5ec92b2da3207298ce3e (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
/*:
 * 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/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/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/suspend.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())

/*
 * Start/end of the hibernate exit code, this must be copied to a 'safe'
 * location in memory, and executed from there.
 */
extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[];

/* 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[];

/*
 * 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;
} 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;

	return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_save);

int arch_hibernation_header_restore(void *addr)
{
	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;
	}

	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 */
	asm volatile("msr	ttbr0_el1, %0;"
		     "isb;"
		     "tlbi	vmalle1is;"
		     "dsb	ish;"
		     "isb" : : "r"(virt_to_phys(pgd)));

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

out:
	return rc;
}


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

	local_dbg_save(flags);

	if (__cpu_suspend_enter(&state)) {
		ret = swsusp_save();
	} else {
		/* Clean kernel to PoC for secondary core startup */
		__flush_dcache_area(LMADDR(KERNEL_START), KERNEL_END - KERNEL_START);

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

		__cpu_suspend_exit();
	}

	local_dbg_restore(flags);

	return ret;
}

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 {
		if (!pte_none(*src_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(pte_val(*src_pte) & ~PTE_RDONLY));
	} 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);

	/*
	 * 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);

	/*
	 * 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);

	/*
	 * 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);
	}

	/*
	 * 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);

	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;
}