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
  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  */
 126 void page_key_write(void *address)
 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
 152 void save_processor_state(void)
 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          */
 164         local_mcck_disable();
 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
 173 void restore_processor_state(void)
 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);
 181         local_mcck_enable();
 182 }