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/mm.h>
  11 #include <asm/system.h>
  12
  13 /*
  14  * References to section boundaries
  15  */
  16 extern const void __nosave_begin, __nosave_end;
  17
  18 /*
  19  * The restore of the saved pages in an hibernation image will set
  20  * the change and referenced bits in the storage key for each page.
  21  * Overindication of the referenced bits after an hibernation cycle
  22  * does not cause any harm but the overindication of the change bits
  23  * would cause trouble.
  24  * Use the ARCH_SAVE_PAGE_KEYS hooks to save the storage key of each
  25  * page to the most significant byte of the associated page frame
  26  * number in the hibernation image.
  27  */
  28
  29 /*
  30  * Key storage is allocated as a linked list of pages.
  31  * The size of the keys array is (PAGE_SIZE - sizeof(long))
  32  */
  33 struct page_key_data {
  34         struct page_key_data *next;
  35         unsigned char data[];
  36 };
  37
  38 #define PAGE_KEY_DATA_SIZE      (PAGE_SIZE - sizeof(struct page_key_data *))
  39
  40 static struct page_key_data *page_key_data;
  41 static struct page_key_data *page_key_rp, *page_key_wp;
  42 static unsigned long page_key_rx, page_key_wx;
  43
  44 /*
  45  * For each page in the hibernation image one additional byte is
  46  * stored in the most significant byte of the page frame number.
  47  * On suspend no additional memory is required but on resume the
  48  * keys need to be memorized until the page data has been restored.
  49  * Only then can the storage keys be set to their old state.
  50  */
  51 unsigned long page_key_additional_pages(unsigned long pages)
  52 {
  53         return DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
  54 }
  55
  56 /*
  57  * Free page_key_data list of arrays.
  58  */
  59 void page_key_free(void)
  60 {
  61         struct page_key_data *pkd;
  62
  63         while (page_key_data) {
  64                 pkd = page_key_data;
  65                 page_key_data = pkd->next;
  66                 free_page((unsigned long) pkd);
  67         }
  68 }
  69
  70 /*
  71  * Allocate page_key_data list of arrays with enough room to store
  72  * one byte for each page in the hibernation image.
  73  */
  74 int page_key_alloc(unsigned long pages)
  75 {
  76         struct page_key_data *pk;
  77         unsigned long size;
  78
  79         size = DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
  80         while (size--) {
  81                 pk = (struct page_key_data *) get_zeroed_page(GFP_KERNEL);
  82                 if (!pk) {
  83                         page_key_free();
  84                         return -ENOMEM;
  85                 }
  86                 pk->next = page_key_data;
  87                 page_key_data = pk;
  88         }
  89         page_key_rp = page_key_wp = page_key_data;
  90         page_key_rx = page_key_wx = 0;
  91         return 0;
  92 }
  93
  94 /*
  95  * Save the storage key into the upper 8 bits of the page frame number.
  96  */
  97 void page_key_read(unsigned long *pfn)
  98 {
  99         unsigned long addr;
 100
 101         addr = (unsigned long) page_address(pfn_to_page(*pfn));
 102         *(unsigned char *) pfn = (unsigned char) page_get_storage_key(addr);
 103 }
 104
 105 /*
 106  * Extract the storage key from the upper 8 bits of the page frame number
 107  * and store it in the page_key_data list of arrays.
 108  */
 109 void page_key_memorize(unsigned long *pfn)
 110 {
 111         page_key_wp->data[page_key_wx] = *(unsigned char *) pfn;
 112         *(unsigned char *) pfn = 0;
 113         if (++page_key_wx < PAGE_KEY_DATA_SIZE)
 114                 return;
 115         page_key_wp = page_key_wp->next;
 116         page_key_wx = 0;
 117 }
 118
 119 /*
 120  * Get the next key from the page_key_data list of arrays and set the
 121  * storage key of the page referred by @address. If @address refers to
 122  * a "safe" page the swsusp_arch_resume code will transfer the storage
 123  * key from the buffer page to the original page.
 124  */
 125 void page_key_write(void *address)
 126 {
 127         page_set_storage_key((unsigned long) address,
 128                              page_key_rp->data[page_key_rx], 0);
 129         if (++page_key_rx >= PAGE_KEY_DATA_SIZE)
 130                 return;
 131         page_key_rp = page_key_rp->next;
 132         page_key_rx = 0;
 133 }
 134
 135 int pfn_is_nosave(unsigned long pfn)
 136 {
 137         unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
 138         unsigned long nosave_end_pfn = PFN_DOWN(__pa(&__nosave_end));
 139
 140         /* Always save lowcore pages (LC protection might be enabled). */
 141         if (pfn <= LC_PAGES)
 142                 return 0;
 143         if (pfn >= nosave_begin_pfn && pfn < nosave_end_pfn)
 144                 return 1;
 145         /* Skip memory holes and read-only pages (NSS, DCSS, ...). */
 146         if (tprot(PFN_PHYS(pfn)))
 147                 return 1;
 148         return 0;
 149 }
 150
 151 void save_processor_state(void)
 152 {
 153         /* swsusp_arch_suspend() actually saves all cpu register contents.
 154          * Machine checks must be disabled since swsusp_arch_suspend() stores
 155          * register contents to their lowcore save areas. That's the same
 156          * place where register contents on machine checks would be saved.
 157          * To avoid register corruption disable machine checks.
 158          * We must also disable machine checks in the new psw mask for
 159          * program checks, since swsusp_arch_suspend() may generate program
 160          * checks. Disabling machine checks for all other new psw masks is
 161          * just paranoia.
 162          */
 163         local_mcck_disable();
 164         /* Disable lowcore protection */
 165         __ctl_clear_bit(0,28);
 166         S390_lowcore.external_new_psw.mask &= ~PSW_MASK_MCHECK;
 167         S390_lowcore.svc_new_psw.mask &= ~PSW_MASK_MCHECK;
 168         S390_lowcore.io_new_psw.mask &= ~PSW_MASK_MCHECK;
 169         S390_lowcore.program_new_psw.mask &= ~PSW_MASK_MCHECK;
 170 }
 171
 172 void restore_processor_state(void)
 173 {
 174         S390_lowcore.external_new_psw.mask |= PSW_MASK_MCHECK;
 175         S390_lowcore.svc_new_psw.mask |= PSW_MASK_MCHECK;
 176         S390_lowcore.io_new_psw.mask |= PSW_MASK_MCHECK;
 177         S390_lowcore.program_new_psw.mask |= PSW_MASK_MCHECK;
 178         /* Enable lowcore protection */
 179         __ctl_set_bit(0,28);
 180         local_mcck_enable();
 181 }