1 /* 2 * handle transition of Linux booting another kernel 3 * Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com> 4 * 5 * This source code is licensed under the GNU General Public License, 6 * Version 2. See the file COPYING for more details. 7 */ 8 9 #include <linux/mm.h> 10 #include <linux/kexec.h> 11 #include <linux/string.h> 12 #include <linux/reboot.h> 13 #include <linux/numa.h> 14 #include <linux/ftrace.h> 15 #include <linux/io.h> 16 #include <linux/suspend.h> 17 18 #include <asm/pgtable.h> 19 #include <asm/tlbflush.h> 20 #include <asm/mmu_context.h> 21 22 static int init_one_level2_page(struct kimage *image, pgd_t *pgd, 23 unsigned long addr) 24 { 25 pud_t *pud; 26 pmd_t *pmd; 27 struct page *page; 28 int result = -ENOMEM; 29 30 addr &= PMD_MASK; 31 pgd += pgd_index(addr); 32 if (!pgd_present(*pgd)) { 33 page = kimage_alloc_control_pages(image, 0); 34 if (!page) 35 goto out; 36 pud = (pud_t *)page_address(page); 37 memset(pud, 0, PAGE_SIZE); 38 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE)); 39 } 40 pud = pud_offset(pgd, addr); 41 if (!pud_present(*pud)) { 42 page = kimage_alloc_control_pages(image, 0); 43 if (!page) 44 goto out; 45 pmd = (pmd_t *)page_address(page); 46 memset(pmd, 0, PAGE_SIZE); 47 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE)); 48 } 49 pmd = pmd_offset(pud, addr); 50 if (!pmd_present(*pmd)) 51 set_pmd(pmd, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC)); 52 result = 0; 53 out: 54 return result; 55 } 56 57 static void init_level2_page(pmd_t *level2p, unsigned long addr) 58 { 59 unsigned long end_addr; 60 61 addr &= PAGE_MASK; 62 end_addr = addr + PUD_SIZE; 63 while (addr < end_addr) { 64 set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC)); 65 addr += PMD_SIZE; 66 } 67 } 68 69 static int init_level3_page(struct kimage *image, pud_t *level3p, 70 unsigned long addr, unsigned long last_addr) 71 { 72 unsigned long end_addr; 73 int result; 74 75 result = 0; 76 addr &= PAGE_MASK; 77 end_addr = addr + PGDIR_SIZE; 78 while ((addr < last_addr) && (addr < end_addr)) { 79 struct page *page; 80 pmd_t *level2p; 81 82 page = kimage_alloc_control_pages(image, 0); 83 if (!page) { 84 result = -ENOMEM; 85 goto out; 86 } 87 level2p = (pmd_t *)page_address(page); 88 init_level2_page(level2p, addr); 89 set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE)); 90 addr += PUD_SIZE; 91 } 92 /* clear the unused entries */ 93 while (addr < end_addr) { 94 pud_clear(level3p++); 95 addr += PUD_SIZE; 96 } 97 out: 98 return result; 99 } 100 101 102 static int init_level4_page(struct kimage *image, pgd_t *level4p, 103 unsigned long addr, unsigned long last_addr) 104 { 105 unsigned long end_addr; 106 int result; 107 108 result = 0; 109 addr &= PAGE_MASK; 110 end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE); 111 while ((addr < last_addr) && (addr < end_addr)) { 112 struct page *page; 113 pud_t *level3p; 114 115 page = kimage_alloc_control_pages(image, 0); 116 if (!page) { 117 result = -ENOMEM; 118 goto out; 119 } 120 level3p = (pud_t *)page_address(page); 121 result = init_level3_page(image, level3p, addr, last_addr); 122 if (result) 123 goto out; 124 set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE)); 125 addr += PGDIR_SIZE; 126 } 127 /* clear the unused entries */ 128 while (addr < end_addr) { 129 pgd_clear(level4p++); 130 addr += PGDIR_SIZE; 131 } 132 out: 133 return result; 134 } 135 136 static void free_transition_pgtable(struct kimage *image) 137 { 138 free_page((unsigned long)image->arch.pud); 139 free_page((unsigned long)image->arch.pmd); 140 free_page((unsigned long)image->arch.pte); 141 } 142 143 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) 144 { 145 pud_t *pud; 146 pmd_t *pmd; 147 pte_t *pte; 148 unsigned long vaddr, paddr; 149 int result = -ENOMEM; 150 151 vaddr = (unsigned long)relocate_kernel; 152 paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE); 153 pgd += pgd_index(vaddr); 154 if (!pgd_present(*pgd)) { 155 pud = (pud_t *)get_zeroed_page(GFP_KERNEL); 156 if (!pud) 157 goto err; 158 image->arch.pud = pud; 159 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE)); 160 } 161 pud = pud_offset(pgd, vaddr); 162 if (!pud_present(*pud)) { 163 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL); 164 if (!pmd) 165 goto err; 166 image->arch.pmd = pmd; 167 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE)); 168 } 169 pmd = pmd_offset(pud, vaddr); 170 if (!pmd_present(*pmd)) { 171 pte = (pte_t *)get_zeroed_page(GFP_KERNEL); 172 if (!pte) 173 goto err; 174 image->arch.pte = pte; 175 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE)); 176 } 177 pte = pte_offset_kernel(pmd, vaddr); 178 set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC)); 179 return 0; 180 err: 181 free_transition_pgtable(image); 182 return result; 183 } 184 185 186 static int init_pgtable(struct kimage *image, unsigned long start_pgtable) 187 { 188 pgd_t *level4p; 189 int result; 190 level4p = (pgd_t *)__va(start_pgtable); 191 result = init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT); 192 if (result) 193 return result; 194 /* 195 * image->start may be outside 0 ~ max_pfn, for example when 196 * jump back to original kernel from kexeced kernel 197 */ 198 result = init_one_level2_page(image, level4p, image->start); 199 if (result) 200 return result; 201 return init_transition_pgtable(image, level4p); 202 } 203 204 static void set_idt(void *newidt, u16 limit) 205 { 206 struct desc_ptr curidt; 207 208 /* x86-64 supports unaliged loads & stores */ 209 curidt.size = limit; 210 curidt.address = (unsigned long)newidt; 211 212 __asm__ __volatile__ ( 213 "lidtq %0\n" 214 : : "m" (curidt) 215 ); 216 }; 217 218 219 static void set_gdt(void *newgdt, u16 limit) 220 { 221 struct desc_ptr curgdt; 222 223 /* x86-64 supports unaligned loads & stores */ 224 curgdt.size = limit; 225 curgdt.address = (unsigned long)newgdt; 226 227 __asm__ __volatile__ ( 228 "lgdtq %0\n" 229 : : "m" (curgdt) 230 ); 231 }; 232 233 static void load_segments(void) 234 { 235 __asm__ __volatile__ ( 236 "\tmovl %0,%%ds\n" 237 "\tmovl %0,%%es\n" 238 "\tmovl %0,%%ss\n" 239 "\tmovl %0,%%fs\n" 240 "\tmovl %0,%%gs\n" 241 : : "a" (__KERNEL_DS) : "memory" 242 ); 243 } 244 245 int machine_kexec_prepare(struct kimage *image) 246 { 247 unsigned long start_pgtable; 248 int result; 249 250 /* Calculate the offsets */ 251 start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT; 252 253 /* Setup the identity mapped 64bit page table */ 254 result = init_pgtable(image, start_pgtable); 255 if (result) 256 return result; 257 258 return 0; 259 } 260 261 void machine_kexec_cleanup(struct kimage *image) 262 { 263 free_transition_pgtable(image); 264 } 265 266 /* 267 * Do not allocate memory (or fail in any way) in machine_kexec(). 268 * We are past the point of no return, committed to rebooting now. 269 */ 270 void machine_kexec(struct kimage *image) 271 { 272 unsigned long page_list[PAGES_NR]; 273 void *control_page; 274 int save_ftrace_enabled; 275 276 #ifdef CONFIG_KEXEC_JUMP 277 if (image->preserve_context) 278 save_processor_state(); 279 #endif 280 281 save_ftrace_enabled = __ftrace_enabled_save(); 282 283 /* Interrupts aren't acceptable while we reboot */ 284 local_irq_disable(); 285 286 if (image->preserve_context) { 287 #ifdef CONFIG_X86_IO_APIC 288 /* 289 * We need to put APICs in legacy mode so that we can 290 * get timer interrupts in second kernel. kexec/kdump 291 * paths already have calls to disable_IO_APIC() in 292 * one form or other. kexec jump path also need 293 * one. 294 */ 295 disable_IO_APIC(); 296 #endif 297 } 298 299 control_page = page_address(image->control_code_page) + PAGE_SIZE; 300 memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE); 301 302 page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page); 303 page_list[VA_CONTROL_PAGE] = (unsigned long)control_page; 304 page_list[PA_TABLE_PAGE] = 305 (unsigned long)__pa(page_address(image->control_code_page)); 306 307 if (image->type == KEXEC_TYPE_DEFAULT) 308 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) 309 << PAGE_SHIFT); 310 311 /* 312 * The segment registers are funny things, they have both a 313 * visible and an invisible part. Whenever the visible part is 314 * set to a specific selector, the invisible part is loaded 315 * with from a table in memory. At no other time is the 316 * descriptor table in memory accessed. 317 * 318 * I take advantage of this here by force loading the 319 * segments, before I zap the gdt with an invalid value. 320 */ 321 load_segments(); 322 /* 323 * The gdt & idt are now invalid. 324 * If you want to load them you must set up your own idt & gdt. 325 */ 326 set_gdt(phys_to_virt(0), 0); 327 set_idt(phys_to_virt(0), 0); 328 329 /* now call it */ 330 image->start = relocate_kernel((unsigned long)image->head, 331 (unsigned long)page_list, 332 image->start, 333 image->preserve_context); 334 335 #ifdef CONFIG_KEXEC_JUMP 336 if (image->preserve_context) 337 restore_processor_state(); 338 #endif 339 340 __ftrace_enabled_restore(save_ftrace_enabled); 341 } 342 343 void arch_crash_save_vmcoreinfo(void) 344 { 345 VMCOREINFO_SYMBOL(phys_base); 346 VMCOREINFO_SYMBOL(init_level4_pgt); 347 348 #ifdef CONFIG_NUMA 349 VMCOREINFO_SYMBOL(node_data); 350 VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); 351 #endif 352 } 353 354