arch/s390/kernel/suspend.c

   1 /*
   2  * Suspend support specific for s390.
   3  *
   4  * Copyright IBM Corp. 2009
   5  *
   6  * Author(s): Hans-Joachim Picht <hans@linux.vnet.ibm.com>
   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 {
  35         struct page_key_data *next;
  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 unsigned long suspend_zero_pages;
  45
  46 /*
  47  * For each page in the hibernation image one additional byte is
  48  * stored in the most significant byte of the page frame number.
  49  * On suspend no additional memory is required but on resume the
  50  * keys need to be memorized until the page data has been restored.
  51  * Only then can the storage keys be set to their old state.
  52  */
  53 unsigned long page_key_additional_pages(unsigned long pages)
  54 {
  55         return DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
  56 }
  57
  58 /*
  59  * Free page_key_data list of arrays.
  60  */
  61 void page_key_free(void)
  62 {
  63         struct page_key_data *pkd;
  64
  65         while (page_key_data) {
  66                 pkd = page_key_data;
  67                 page_key_data = pkd->next;
  68                 free_page((unsigned long) pkd);
  69         }
  70 }
  71
  72 /*
  73  * Allocate page_key_data list of arrays with enough room to store
  74  * one byte for each page in the hibernation image.
  75  */
  76 int page_key_alloc(unsigned long pages)
  77 {
  78         struct page_key_data *pk;
  79         unsigned long size;
  80
  81         size = DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
  82         while (size--) {
  83                 pk = (struct page_key_data *) get_zeroed_page(GFP_KERNEL);
  84                 if (!pk) {
  85                         page_key_free();
  86                         return -ENOMEM;
  87                 }
  88                 pk->next = page_key_data;
  89                 page_key_data = pk;
  90         }
  91         page_key_rp = page_key_wp = page_key_data;
  92         page_key_rx = page_key_wx = 0;
  93         return 0;
  94 }
  95
  96 /*
  97  * Save the storage key into the upper 8 bits of the page frame number.
  98  */
  99 void page_key_read(unsigned long *pfn)
 100 {
 101         unsigned long addr;
 102
 103         addr = (unsigned long) page_address(pfn_to_page(*pfn));
 104         *(unsigned char *) pfn = (unsigned char) page_get_storage_key(addr);
 105 }
 106
 107 /*
 108  * Extract the storage key from the upper 8 bits of the page frame number
 109  * and store it in the page_key_data list of arrays.
 110  */
 111 void page_key_memorize(unsigned long *pfn)
 112 {
 113         page_key_wp->data[page_key_wx] = *(unsigned char *) pfn;
 114         *(unsigned char *) pfn = 0;
 115         if (++page_key_wx < PAGE_KEY_DATA_SIZE)
 116                 return;
 117         page_key_wp = page_key_wp->next;
 118         page_key_wx = 0;
 119 }
 120
 121 /*
 122  * Get the next key from the page_key_data list of arrays and set the
 123  * storage key of the page referred by @address. If @address refers to
 124  * a "safe" page the swsusp_arch_resume code will transfer the storage
 125  * key from the buffer page to the original page.
 126  */
 127 void page_key_write(void *address)
 128 {
 129         page_set_storage_key((unsigned long) address,
 130                              page_key_rp->data[page_key_rx], 0);
 131         if (++page_key_rx >= PAGE_KEY_DATA_SIZE)
 132                 return;
 133         page_key_rp = page_key_rp->next;
 134         page_key_rx = 0;
 135 }
 136
 137 int pfn_is_nosave(unsigned long pfn)
 138 {
 139         unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
 140         unsigned long nosave_end_pfn = PFN_DOWN(__pa(&__nosave_end));
 141
 142         /* Always save lowcore pages (LC protection might be enabled). */
 143         if (pfn <= LC_PAGES)
 144                 return 0;
 145         if (pfn >= nosave_begin_pfn && pfn < nosave_end_pfn)
 146                 return 1;
 147         /* Skip memory holes and read-only pages (NSS, DCSS, ...). */
 148         if (tprot(PFN_PHYS(pfn)))
 149                 return 1;
 150         return 0;
 151 }
 152
 153 /*
 154  * PM notifier callback for suspend
 155  */
 156 static int suspend_pm_cb(struct notifier_block *nb, unsigned long action,
 157                          void *ptr)
 158 {
 159         switch (action) {
 160         case PM_SUSPEND_PREPARE:
 161         case PM_HIBERNATION_PREPARE:
 162                 suspend_zero_pages = __get_free_pages(GFP_KERNEL, LC_ORDER);
 163                 if (!suspend_zero_pages)
 164                         return NOTIFY_BAD;
 165                 break;
 166         case PM_POST_SUSPEND:
 167         case PM_POST_HIBERNATION:
 168                 free_pages(suspend_zero_pages, LC_ORDER);
 169                 break;
 170         default:
 171                 return NOTIFY_DONE;
 172         }
 173         return NOTIFY_OK;
 174 }
 175
 176 static int __init suspend_pm_init(void)
 177 {
 178         pm_notifier(suspend_pm_cb, 0);
 179         return 0;
 180 }
 181 arch_initcall(suspend_pm_init);
 182
 183 void save_processor_state(void)
 184 {
 185         /* swsusp_arch_suspend() actually saves all cpu register contents.
 186          * Machine checks must be disabled since swsusp_arch_suspend() stores
 187          * register contents to their lowcore save areas. That's the same
 188          * place where register contents on machine checks would be saved.
 189          * To avoid register corruption disable machine checks.
 190          * We must also disable machine checks in the new psw mask for
 191          * program checks, since swsusp_arch_suspend() may generate program
 192          * checks. Disabling machine checks for all other new psw masks is
 193          * just paranoia.
 194          */
 195         local_mcck_disable();
 196         /* Disable lowcore protection */
 197         __ctl_clear_bit(0,28);
 198         S390_lowcore.external_new_psw.mask &= ~PSW_MASK_MCHECK;
 199         S390_lowcore.svc_new_psw.mask &= ~PSW_MASK_MCHECK;
 200         S390_lowcore.io_new_psw.mask &= ~PSW_MASK_MCHECK;
 201         S390_lowcore.program_new_psw.mask &= ~PSW_MASK_MCHECK;
 202 }
 203
 204 void restore_processor_state(void)
 205 {
 206         S390_lowcore.external_new_psw.mask |= PSW_MASK_MCHECK;
 207         S390_lowcore.svc_new_psw.mask |= PSW_MASK_MCHECK;
 208         S390_lowcore.io_new_psw.mask |= PSW_MASK_MCHECK;
 209         S390_lowcore.program_new_psw.mask |= PSW_MASK_MCHECK;
 210         /* Enable lowcore protection */
 211         __ctl_set_bit(0,28);
 212         local_mcck_enable();
 213 }