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Linux/arch/x86/power/hibernate.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Hibernation support for x86
  4  *
  5  * Copyright (c) 2007 Rafael J. Wysocki <rjw@sisk.pl>
  6  * Copyright (c) 2002 Pavel Machek <pavel@ucw.cz>
  7  * Copyright (c) 2001 Patrick Mochel <mochel@osdl.org>
  8  */
  9 #include <linux/gfp.h>
 10 #include <linux/smp.h>
 11 #include <linux/suspend.h>
 12 #include <linux/scatterlist.h>
 13 #include <linux/kdebug.h>
 14 
 15 #include <crypto/hash.h>
 16 
 17 #include <asm/e820/api.h>
 18 #include <asm/init.h>
 19 #include <asm/proto.h>
 20 #include <asm/page.h>
 21 #include <asm/pgtable.h>
 22 #include <asm/mtrr.h>
 23 #include <asm/sections.h>
 24 #include <asm/suspend.h>
 25 #include <asm/tlbflush.h>
 26 
 27 /*
 28  * Address to jump to in the last phase of restore in order to get to the image
 29  * kernel's text (this value is passed in the image header).
 30  */
 31 unsigned long restore_jump_address __visible;
 32 unsigned long jump_address_phys;
 33 
 34 /*
 35  * Value of the cr3 register from before the hibernation (this value is passed
 36  * in the image header).
 37  */
 38 unsigned long restore_cr3 __visible;
 39 unsigned long temp_pgt __visible;
 40 unsigned long relocated_restore_code __visible;
 41 
 42 /**
 43  *      pfn_is_nosave - check if given pfn is in the 'nosave' section
 44  */
 45 int pfn_is_nosave(unsigned long pfn)
 46 {
 47         unsigned long nosave_begin_pfn;
 48         unsigned long nosave_end_pfn;
 49 
 50         nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
 51         nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
 52 
 53         return pfn >= nosave_begin_pfn && pfn < nosave_end_pfn;
 54 }
 55 
 56 
 57 #define MD5_DIGEST_SIZE 16
 58 
 59 struct restore_data_record {
 60         unsigned long jump_address;
 61         unsigned long jump_address_phys;
 62         unsigned long cr3;
 63         unsigned long magic;
 64         u8 e820_digest[MD5_DIGEST_SIZE];
 65 };
 66 
 67 #if IS_BUILTIN(CONFIG_CRYPTO_MD5)
 68 /**
 69  * get_e820_md5 - calculate md5 according to given e820 table
 70  *
 71  * @table: the e820 table to be calculated
 72  * @buf: the md5 result to be stored to
 73  */
 74 static int get_e820_md5(struct e820_table *table, void *buf)
 75 {
 76         struct crypto_shash *tfm;
 77         struct shash_desc *desc;
 78         int size;
 79         int ret = 0;
 80 
 81         tfm = crypto_alloc_shash("md5", 0, 0);
 82         if (IS_ERR(tfm))
 83                 return -ENOMEM;
 84 
 85         desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
 86                        GFP_KERNEL);
 87         if (!desc) {
 88                 ret = -ENOMEM;
 89                 goto free_tfm;
 90         }
 91 
 92         desc->tfm = tfm;
 93         desc->flags = 0;
 94 
 95         size = offsetof(struct e820_table, entries) +
 96                 sizeof(struct e820_entry) * table->nr_entries;
 97 
 98         if (crypto_shash_digest(desc, (u8 *)table, size, buf))
 99                 ret = -EINVAL;
100 
101         kzfree(desc);
102 
103 free_tfm:
104         crypto_free_shash(tfm);
105         return ret;
106 }
107 
108 static int hibernation_e820_save(void *buf)
109 {
110         return get_e820_md5(e820_table_firmware, buf);
111 }
112 
113 static bool hibernation_e820_mismatch(void *buf)
114 {
115         int ret;
116         u8 result[MD5_DIGEST_SIZE];
117 
118         memset(result, 0, MD5_DIGEST_SIZE);
119         /* If there is no digest in suspend kernel, let it go. */
120         if (!memcmp(result, buf, MD5_DIGEST_SIZE))
121                 return false;
122 
123         ret = get_e820_md5(e820_table_firmware, result);
124         if (ret)
125                 return true;
126 
127         return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
128 }
129 #else
130 static int hibernation_e820_save(void *buf)
131 {
132         return 0;
133 }
134 
135 static bool hibernation_e820_mismatch(void *buf)
136 {
137         /* If md5 is not builtin for restore kernel, let it go. */
138         return false;
139 }
140 #endif
141 
142 #ifdef CONFIG_X86_64
143 #define RESTORE_MAGIC   0x23456789ABCDEF01UL
144 #else
145 #define RESTORE_MAGIC   0x12345678UL
146 #endif
147 
148 /**
149  *      arch_hibernation_header_save - populate the architecture specific part
150  *              of a hibernation image header
151  *      @addr: address to save the data at
152  */
153 int arch_hibernation_header_save(void *addr, unsigned int max_size)
154 {
155         struct restore_data_record *rdr = addr;
156 
157         if (max_size < sizeof(struct restore_data_record))
158                 return -EOVERFLOW;
159         rdr->magic = RESTORE_MAGIC;
160         rdr->jump_address = (unsigned long)restore_registers;
161         rdr->jump_address_phys = __pa_symbol(restore_registers);
162 
163         /*
164          * The restore code fixes up CR3 and CR4 in the following sequence:
165          *
166          * [in hibernation asm]
167          * 1. CR3 <= temporary page tables
168          * 2. CR4 <= mmu_cr4_features (from the kernel that restores us)
169          * 3. CR3 <= rdr->cr3
170          * 4. CR4 <= mmu_cr4_features (from us, i.e. the image kernel)
171          * [in restore_processor_state()]
172          * 5. CR4 <= saved CR4
173          * 6. CR3 <= saved CR3
174          *
175          * Our mmu_cr4_features has CR4.PCIDE=0, and toggling
176          * CR4.PCIDE while CR3's PCID bits are nonzero is illegal, so
177          * rdr->cr3 needs to point to valid page tables but must not
178          * have any of the PCID bits set.
179          */
180         rdr->cr3 = restore_cr3 & ~CR3_PCID_MASK;
181 
182         return hibernation_e820_save(rdr->e820_digest);
183 }
184 
185 /**
186  *      arch_hibernation_header_restore - read the architecture specific data
187  *              from the hibernation image header
188  *      @addr: address to read the data from
189  */
190 int arch_hibernation_header_restore(void *addr)
191 {
192         struct restore_data_record *rdr = addr;
193 
194         if (rdr->magic != RESTORE_MAGIC) {
195                 pr_crit("Unrecognized hibernate image header format!\n");
196                 return -EINVAL;
197         }
198 
199         restore_jump_address = rdr->jump_address;
200         jump_address_phys = rdr->jump_address_phys;
201         restore_cr3 = rdr->cr3;
202 
203         if (hibernation_e820_mismatch(rdr->e820_digest)) {
204                 pr_crit("Hibernate inconsistent memory map detected!\n");
205                 return -ENODEV;
206         }
207 
208         return 0;
209 }
210 
211 int relocate_restore_code(void)
212 {
213         pgd_t *pgd;
214         p4d_t *p4d;
215         pud_t *pud;
216         pmd_t *pmd;
217         pte_t *pte;
218 
219         relocated_restore_code = get_safe_page(GFP_ATOMIC);
220         if (!relocated_restore_code)
221                 return -ENOMEM;
222 
223         memcpy((void *)relocated_restore_code, core_restore_code, PAGE_SIZE);
224 
225         /* Make the page containing the relocated code executable */
226         pgd = (pgd_t *)__va(read_cr3_pa()) +
227                 pgd_index(relocated_restore_code);
228         p4d = p4d_offset(pgd, relocated_restore_code);
229         if (p4d_large(*p4d)) {
230                 set_p4d(p4d, __p4d(p4d_val(*p4d) & ~_PAGE_NX));
231                 goto out;
232         }
233         pud = pud_offset(p4d, relocated_restore_code);
234         if (pud_large(*pud)) {
235                 set_pud(pud, __pud(pud_val(*pud) & ~_PAGE_NX));
236                 goto out;
237         }
238         pmd = pmd_offset(pud, relocated_restore_code);
239         if (pmd_large(*pmd)) {
240                 set_pmd(pmd, __pmd(pmd_val(*pmd) & ~_PAGE_NX));
241                 goto out;
242         }
243         pte = pte_offset_kernel(pmd, relocated_restore_code);
244         set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_NX));
245 out:
246         __flush_tlb_all();
247         return 0;
248 }
249 

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