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 */
 17extern 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 */
 34struct 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
 41static struct page_key_data *page_key_data;
 42static struct page_key_data *page_key_rp, *page_key_wp;
 43static 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 */
 52unsigned 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 */
 60void 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 */
 75int 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 */
 98void 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 */
110void 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 */
126void 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
136int 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
152void 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
173void 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}