Linux Kernel  3.7.1
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suspend.c
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1 /*
2  * Suspend support specific for s390.
3  *
4  * Copyright IBM Corp. 2009
5  *
6  * Author(s): Hans-Joachim Picht <[email protected]>
7  */
8 
9 #include <linux/pfn.h>
10 #include <linux/suspend.h>
11 #include <linux/mm.h>
12 #include <asm/ctl_reg.h>
13 
14 /*
15  * References to section boundaries
16  */
17 extern const void __nosave_begin, __nosave_end;
18 
19 /*
20  * The restore of the saved pages in an hibernation image will set
21  * the change and referenced bits in the storage key for each page.
22  * Overindication of the referenced bits after an hibernation cycle
23  * does not cause any harm but the overindication of the change bits
24  * would cause trouble.
25  * Use the ARCH_SAVE_PAGE_KEYS hooks to save the storage key of each
26  * page to the most significant byte of the associated page frame
27  * number in the hibernation image.
28  */
29 
30 /*
31  * Key storage is allocated as a linked list of pages.
32  * The size of the keys array is (PAGE_SIZE - sizeof(long))
33  */
34 struct page_key_data {
36  unsigned char data[];
37 };
38 
39 #define PAGE_KEY_DATA_SIZE (PAGE_SIZE - sizeof(struct page_key_data *))
40 
41 static struct page_key_data *page_key_data;
42 static struct page_key_data *page_key_rp, *page_key_wp;
43 static unsigned long page_key_rx, page_key_wx;
44 
45 /*
46  * For each page in the hibernation image one additional byte is
47  * stored in the most significant byte of the page frame number.
48  * On suspend no additional memory is required but on resume the
49  * keys need to be memorized until the page data has been restored.
50  * Only then can the storage keys be set to their old state.
51  */
52 unsigned long page_key_additional_pages(unsigned long pages)
53 {
54  return DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
55 }
56 
57 /*
58  * Free page_key_data list of arrays.
59  */
60 void page_key_free(void)
61 {
62  struct page_key_data *pkd;
63 
64  while (page_key_data) {
65  pkd = page_key_data;
66  page_key_data = pkd->next;
67  free_page((unsigned long) pkd);
68  }
69 }
70 
71 /*
72  * Allocate page_key_data list of arrays with enough room to store
73  * one byte for each page in the hibernation image.
74  */
75 int page_key_alloc(unsigned long pages)
76 {
77  struct page_key_data *pk;
78  unsigned long size;
79 
80  size = DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
81  while (size--) {
82  pk = (struct page_key_data *) get_zeroed_page(GFP_KERNEL);
83  if (!pk) {
84  page_key_free();
85  return -ENOMEM;
86  }
87  pk->next = page_key_data;
88  page_key_data = pk;
89  }
90  page_key_rp = page_key_wp = page_key_data;
91  page_key_rx = page_key_wx = 0;
92  return 0;
93 }
94 
95 /*
96  * Save the storage key into the upper 8 bits of the page frame number.
97  */
98 void page_key_read(unsigned long *pfn)
99 {
100  unsigned long addr;
101 
102  addr = (unsigned long) page_address(pfn_to_page(*pfn));
103  *(unsigned char *) pfn = (unsigned char) page_get_storage_key(addr);
104 }
105 
106 /*
107  * Extract the storage key from the upper 8 bits of the page frame number
108  * and store it in the page_key_data list of arrays.
109  */
110 void page_key_memorize(unsigned long *pfn)
111 {
112  page_key_wp->data[page_key_wx] = *(unsigned char *) pfn;
113  *(unsigned char *) pfn = 0;
114  if (++page_key_wx < PAGE_KEY_DATA_SIZE)
115  return;
116  page_key_wp = page_key_wp->next;
117  page_key_wx = 0;
118 }
119 
120 /*
121  * Get the next key from the page_key_data list of arrays and set the
122  * storage key of the page referred by @address. If @address refers to
123  * a "safe" page the swsusp_arch_resume code will transfer the storage
124  * key from the buffer page to the original page.
125  */
127 {
128  page_set_storage_key((unsigned long) address,
129  page_key_rp->data[page_key_rx], 0);
130  if (++page_key_rx >= PAGE_KEY_DATA_SIZE)
131  return;
132  page_key_rp = page_key_rp->next;
133  page_key_rx = 0;
134 }
135 
136 int pfn_is_nosave(unsigned long pfn)
137 {
138  unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
139  unsigned long nosave_end_pfn = PFN_DOWN(__pa(&__nosave_end));
140 
141  /* Always save lowcore pages (LC protection might be enabled). */
142  if (pfn <= LC_PAGES)
143  return 0;
144  if (pfn >= nosave_begin_pfn && pfn < nosave_end_pfn)
145  return 1;
146  /* Skip memory holes and read-only pages (NSS, DCSS, ...). */
147  if (tprot(PFN_PHYS(pfn)))
148  return 1;
149  return 0;
150 }
151 
153 {
154  /* swsusp_arch_suspend() actually saves all cpu register contents.
155  * Machine checks must be disabled since swsusp_arch_suspend() stores
156  * register contents to their lowcore save areas. That's the same
157  * place where register contents on machine checks would be saved.
158  * To avoid register corruption disable machine checks.
159  * We must also disable machine checks in the new psw mask for
160  * program checks, since swsusp_arch_suspend() may generate program
161  * checks. Disabling machine checks for all other new psw masks is
162  * just paranoia.
163  */
165  /* Disable lowcore protection */
166  __ctl_clear_bit(0,28);
167  S390_lowcore.external_new_psw.mask &= ~PSW_MASK_MCHECK;
168  S390_lowcore.svc_new_psw.mask &= ~PSW_MASK_MCHECK;
169  S390_lowcore.io_new_psw.mask &= ~PSW_MASK_MCHECK;
170  S390_lowcore.program_new_psw.mask &= ~PSW_MASK_MCHECK;
171 }
172 
174 {
175  S390_lowcore.external_new_psw.mask |= PSW_MASK_MCHECK;
176  S390_lowcore.svc_new_psw.mask |= PSW_MASK_MCHECK;
177  S390_lowcore.io_new_psw.mask |= PSW_MASK_MCHECK;
178  S390_lowcore.program_new_psw.mask |= PSW_MASK_MCHECK;
179  /* Enable lowcore protection */
180  __ctl_set_bit(0,28);
182 }