root/arch/s390/kernel/suspend.c

DEFINITIONS

1. page_key_additional_pages
2. page_key_free
3. page_key_alloc
4. page_key_read
5. page_key_memorize
6. page_key_write
7. pfn_is_nosave
8. suspend_pm_cb
9. suspend_pm_init
10. save_processor_state
11. restore_processor_state
12. s390_early_resume

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Suspend support specific for s390.
   4  *
   5  * Copyright IBM Corp. 2009
   6  *
   7  * Author(s): Hans-Joachim Picht <hans@linux.vnet.ibm.com>
   8  */
   9 
  10 #include <linux/pfn.h>
  11 #include <linux/suspend.h>
  12 #include <linux/mm.h>
  13 #include <linux/pci.h>
  14 #include <asm/ctl_reg.h>
  15 #include <asm/ipl.h>
  16 #include <asm/cio.h>
  17 #include <asm/sections.h>
  18 #include "entry.h"
  19 
  20 /*
  21  * The restore of the saved pages in an hibernation image will set
  22  * the change and referenced bits in the storage key for each page.
  23  * Overindication of the referenced bits after an hibernation cycle
  24  * does not cause any harm but the overindication of the change bits
  25  * would cause trouble.
  26  * Use the ARCH_SAVE_PAGE_KEYS hooks to save the storage key of each
  27  * page to the most significant byte of the associated page frame
  28  * number in the hibernation image.
  29  */
  30 
  31 /*
  32  * Key storage is allocated as a linked list of pages.
  33  * The size of the keys array is (PAGE_SIZE - sizeof(long))
  34  */
  35 struct page_key_data {
  36         struct page_key_data *next;
  37         unsigned char data[];
  38 };
  39 
  40 #define PAGE_KEY_DATA_SIZE      (PAGE_SIZE - sizeof(struct page_key_data *))
  41 
  42 static struct page_key_data *page_key_data;
  43 static struct page_key_data *page_key_rp, *page_key_wp;
  44 static unsigned long page_key_rx, page_key_wx;
  45 unsigned long suspend_zero_pages;
  46 
  47 /*
  48  * For each page in the hibernation image one additional byte is
  49  * stored in the most significant byte of the page frame number.
  50  * On suspend no additional memory is required but on resume the
  51  * keys need to be memorized until the page data has been restored.
  52  * Only then can the storage keys be set to their old state.
  53  */
  54 unsigned long page_key_additional_pages(unsigned long pages)
  55 {
  56         return DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
  57 }
  58 
  59 /*
  60  * Free page_key_data list of arrays.
  61  */
  62 void page_key_free(void)
  63 {
  64         struct page_key_data *pkd;
  65 
  66         while (page_key_data) {
  67                 pkd = page_key_data;
  68                 page_key_data = pkd->next;
  69                 free_page((unsigned long) pkd);
  70         }
  71 }
  72 
  73 /*
  74  * Allocate page_key_data list of arrays with enough room to store
  75  * one byte for each page in the hibernation image.
  76  */
  77 int page_key_alloc(unsigned long pages)
  78 {
  79         struct page_key_data *pk;
  80         unsigned long size;
  81 
  82         size = DIV_ROUND_UP(pages, PAGE_KEY_DATA_SIZE);
  83         while (size--) {
  84                 pk = (struct page_key_data *) get_zeroed_page(GFP_KERNEL);
  85                 if (!pk) {
  86                         page_key_free();
  87                         return -ENOMEM;
  88                 }
  89                 pk->next = page_key_data;
  90                 page_key_data = pk;
  91         }
  92         page_key_rp = page_key_wp = page_key_data;
  93         page_key_rx = page_key_wx = 0;
  94         return 0;
  95 }
  96 
  97 /*
  98  * Save the storage key into the upper 8 bits of the page frame number.
  99  */
 100 void page_key_read(unsigned long *pfn)
 101 {
 102         struct page *page;
 103         unsigned long addr;
 104         unsigned char key;
 105 
 106         page = pfn_to_page(*pfn);
 107         addr = (unsigned long) page_address(page);
 108         key = (unsigned char) page_get_storage_key(addr) & 0x7f;
 109         if (arch_test_page_nodat(page))
 110                 key |= 0x80;
 111         *(unsigned char *) pfn = key;
 112 }
 113 
 114 /*
 115  * Extract the storage key from the upper 8 bits of the page frame number
 116  * and store it in the page_key_data list of arrays.
 117  */
 118 void page_key_memorize(unsigned long *pfn)
 119 {
 120         page_key_wp->data[page_key_wx] = *(unsigned char *) pfn;
 121         *(unsigned char *) pfn = 0;
 122         if (++page_key_wx < PAGE_KEY_DATA_SIZE)
 123                 return;
 124         page_key_wp = page_key_wp->next;
 125         page_key_wx = 0;
 126 }
 127 
 128 /*
 129  * Get the next key from the page_key_data list of arrays and set the
 130  * storage key of the page referred by @address. If @address refers to
 131  * a "safe" page the swsusp_arch_resume code will transfer the storage
 132  * key from the buffer page to the original page.
 133  */
 134 void page_key_write(void *address)
 135 {
 136         struct page *page;
 137         unsigned char key;
 138 
 139         key = page_key_rp->data[page_key_rx];
 140         page_set_storage_key((unsigned long) address, key & 0x7f, 0);
 141         page = virt_to_page(address);
 142         if (key & 0x80)
 143                 arch_set_page_nodat(page, 0);
 144         else
 145                 arch_set_page_dat(page, 0);
 146         if (++page_key_rx >= PAGE_KEY_DATA_SIZE)
 147                 return;
 148         page_key_rp = page_key_rp->next;
 149         page_key_rx = 0;
 150 }
 151 
 152 int pfn_is_nosave(unsigned long pfn)
 153 {
 154         unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
 155         unsigned long nosave_end_pfn = PFN_DOWN(__pa(&__nosave_end));
 156         unsigned long end_rodata_pfn = PFN_DOWN(__pa(__end_rodata)) - 1;
 157         unsigned long stext_pfn = PFN_DOWN(__pa(_stext));
 158 
 159         /* Always save lowcore pages (LC protection might be enabled). */
 160         if (pfn <= LC_PAGES)
 161                 return 0;
 162         if (pfn >= nosave_begin_pfn && pfn < nosave_end_pfn)
 163                 return 1;
 164         /* Skip memory holes and read-only pages (DCSS, ...). */
 165         if (pfn >= stext_pfn && pfn <= end_rodata_pfn)
 166                 return 0;
 167         if (tprot(PFN_PHYS(pfn)))
 168                 return 1;
 169         return 0;
 170 }
 171 
 172 /*
 173  * PM notifier callback for suspend
 174  */
 175 static int suspend_pm_cb(struct notifier_block *nb, unsigned long action,
 176                          void *ptr)
 177 {
 178         switch (action) {
 179         case PM_SUSPEND_PREPARE:
 180         case PM_HIBERNATION_PREPARE:
 181                 suspend_zero_pages = __get_free_pages(GFP_KERNEL, LC_ORDER);
 182                 if (!suspend_zero_pages)
 183                         return NOTIFY_BAD;
 184                 break;
 185         case PM_POST_SUSPEND:
 186         case PM_POST_HIBERNATION:
 187                 free_pages(suspend_zero_pages, LC_ORDER);
 188                 break;
 189         default:
 190                 return NOTIFY_DONE;
 191         }
 192         return NOTIFY_OK;
 193 }
 194 
 195 static int __init suspend_pm_init(void)
 196 {
 197         pm_notifier(suspend_pm_cb, 0);
 198         return 0;
 199 }
 200 arch_initcall(suspend_pm_init);
 201 
 202 void save_processor_state(void)
 203 {
 204         /* swsusp_arch_suspend() actually saves all cpu register contents.
 205          * Machine checks must be disabled since swsusp_arch_suspend() stores
 206          * register contents to their lowcore save areas. That's the same
 207          * place where register contents on machine checks would be saved.
 208          * To avoid register corruption disable machine checks.
 209          * We must also disable machine checks in the new psw mask for
 210          * program checks, since swsusp_arch_suspend() may generate program
 211          * checks. Disabling machine checks for all other new psw masks is
 212          * just paranoia.
 213          */
 214         local_mcck_disable();
 215         /* Disable lowcore protection */
 216         __ctl_clear_bit(0,28);
 217         S390_lowcore.external_new_psw.mask &= ~PSW_MASK_MCHECK;
 218         S390_lowcore.svc_new_psw.mask &= ~PSW_MASK_MCHECK;
 219         S390_lowcore.io_new_psw.mask &= ~PSW_MASK_MCHECK;
 220         S390_lowcore.program_new_psw.mask &= ~PSW_MASK_MCHECK;
 221 }
 222 
 223 void restore_processor_state(void)
 224 {
 225         S390_lowcore.external_new_psw.mask |= PSW_MASK_MCHECK;
 226         S390_lowcore.svc_new_psw.mask |= PSW_MASK_MCHECK;
 227         S390_lowcore.io_new_psw.mask |= PSW_MASK_MCHECK;
 228         S390_lowcore.program_new_psw.mask |= PSW_MASK_MCHECK;
 229         /* Enable lowcore protection */
 230         __ctl_set_bit(0,28);
 231         local_mcck_enable();
 232 }
 233 
 234 /* Called at the end of swsusp_arch_resume */
 235 void s390_early_resume(void)
 236 {
 237         lgr_info_log();
 238         channel_subsystem_reinit();
 239         zpci_rescan();
 240 }