arch/x86/kernel/machine_kexec_64.c

   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/gfp.h>
  13 #include <linux/reboot.h>
  14 #include <linux/numa.h>
  15 #include <linux/ftrace.h>
  16 #include <linux/io.h>
  17 #include <linux/suspend.h>
  18
  19 #include <asm/pgtable.h>
  20 #include <asm/tlbflush.h>
  21 #include <asm/mmu_context.h>
  22 #include <asm/debugreg.h>
  23
  24 static int init_one_level2_page(struct kimage *image, pgd_t *pgd,
  25                                 unsigned long addr)
  26 {
  27         pud_t *pud;
  28         pmd_t *pmd;
  29         struct page *page;
  30         int result = -ENOMEM;
  31
  32         addr &= PMD_MASK;
  33         pgd += pgd_index(addr);
  34         if (!pgd_present(*pgd)) {
  35                 page = kimage_alloc_control_pages(image, 0);
  36                 if (!page)
  37                         goto out;
  38                 pud = (pud_t *)page_address(page);
  39                 memset(pud, 0, PAGE_SIZE);
  40                 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
  41         }
  42         pud = pud_offset(pgd, addr);
  43         if (!pud_present(*pud)) {
  44                 page = kimage_alloc_control_pages(image, 0);
  45                 if (!page)
  46                         goto out;
  47                 pmd = (pmd_t *)page_address(page);
  48                 memset(pmd, 0, PAGE_SIZE);
  49                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
  50         }
  51         pmd = pmd_offset(pud, addr);
  52         if (!pmd_present(*pmd))
  53                 set_pmd(pmd, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
  54         result = 0;
  55 out:
  56         return result;
  57 }
  58
  59 static void init_level2_page(pmd_t *level2p, unsigned long addr)
  60 {
  61         unsigned long end_addr;
  62
  63         addr &= PAGE_MASK;
  64         end_addr = addr + PUD_SIZE;
  65         while (addr < end_addr) {
  66                 set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
  67                 addr += PMD_SIZE;
  68         }
  69 }
  70
  71 static int init_level3_page(struct kimage *image, pud_t *level3p,
  72                                 unsigned long addr, unsigned long last_addr)
  73 {
  74         unsigned long end_addr;
  75         int result;
  76
  77         result = 0;
  78         addr &= PAGE_MASK;
  79         end_addr = addr + PGDIR_SIZE;
  80         while ((addr < last_addr) && (addr < end_addr)) {
  81                 struct page *page;
  82                 pmd_t *level2p;
  83
  84                 page = kimage_alloc_control_pages(image, 0);
  85                 if (!page) {
  86                         result = -ENOMEM;
  87                         goto out;
  88                 }
  89                 level2p = (pmd_t *)page_address(page);
  90                 init_level2_page(level2p, addr);
  91                 set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
  92                 addr += PUD_SIZE;
  93         }
  94         /* clear the unused entries */
  95         while (addr < end_addr) {
  96                 pud_clear(level3p++);
  97                 addr += PUD_SIZE;
  98         }
  99 out:
 100         return result;
 101 }
 102
 103
 104 static int init_level4_page(struct kimage *image, pgd_t *level4p,
 105                                 unsigned long addr, unsigned long last_addr)
 106 {
 107         unsigned long end_addr;
 108         int result;
 109
 110         result = 0;
 111         addr &= PAGE_MASK;
 112         end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
 113         while ((addr < last_addr) && (addr < end_addr)) {
 114                 struct page *page;
 115                 pud_t *level3p;
 116
 117                 page = kimage_alloc_control_pages(image, 0);
 118                 if (!page) {
 119                         result = -ENOMEM;
 120                         goto out;
 121                 }
 122                 level3p = (pud_t *)page_address(page);
 123                 result = init_level3_page(image, level3p, addr, last_addr);
 124                 if (result)
 125                         goto out;
 126                 set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
 127                 addr += PGDIR_SIZE;
 128         }
 129         /* clear the unused entries */
 130         while (addr < end_addr) {
 131                 pgd_clear(level4p++);
 132                 addr += PGDIR_SIZE;
 133         }
 134 out:
 135         return result;
 136 }
 137
 138 static void free_transition_pgtable(struct kimage *image)
 139 {
 140         free_page((unsigned long)image->arch.pud);
 141         free_page((unsigned long)image->arch.pmd);
 142         free_page((unsigned long)image->arch.pte);
 143 }
 144
 145 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 146 {
 147         pud_t *pud;
 148         pmd_t *pmd;
 149         pte_t *pte;
 150         unsigned long vaddr, paddr;
 151         int result = -ENOMEM;
 152
 153         vaddr = (unsigned long)relocate_kernel;
 154         paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
 155         pgd += pgd_index(vaddr);
 156         if (!pgd_present(*pgd)) {
 157                 pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
 158                 if (!pud)
 159                         goto err;
 160                 image->arch.pud = pud;
 161                 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
 162         }
 163         pud = pud_offset(pgd, vaddr);
 164         if (!pud_present(*pud)) {
 165                 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 166                 if (!pmd)
 167                         goto err;
 168                 image->arch.pmd = pmd;
 169                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
 170         }
 171         pmd = pmd_offset(pud, vaddr);
 172         if (!pmd_present(*pmd)) {
 173                 pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
 174                 if (!pte)
 175                         goto err;
 176                 image->arch.pte = pte;
 177                 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
 178         }
 179         pte = pte_offset_kernel(pmd, vaddr);
 180         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
 181         return 0;
 182 err:
 183         free_transition_pgtable(image);
 184         return result;
 185 }
 186
 187
 188 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 189 {
 190         pgd_t *level4p;
 191         int result;
 192         level4p = (pgd_t *)__va(start_pgtable);
 193         result = init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT);
 194         if (result)
 195                 return result;
 196         /*
 197          * image->start may be outside 0 ~ max_pfn, for example when
 198          * jump back to original kernel from kexeced kernel
 199          */
 200         result = init_one_level2_page(image, level4p, image->start);
 201         if (result)
 202                 return result;
 203         return init_transition_pgtable(image, level4p);
 204 }
 205
 206 static void set_idt(void *newidt, u16 limit)
 207 {
 208         struct desc_ptr curidt;
 209
 210         /* x86-64 supports unaliged loads & stores */
 211         curidt.size    = limit;
 212         curidt.address = (unsigned long)newidt;
 213
 214         __asm__ __volatile__ (
 215                 "lidtq %0\n"
 216                 : : "m" (curidt)
 217                 );
 218 };
 219
 220
 221 static void set_gdt(void *newgdt, u16 limit)
 222 {
 223         struct desc_ptr curgdt;
 224
 225         /* x86-64 supports unaligned loads & stores */
 226         curgdt.size    = limit;
 227         curgdt.address = (unsigned long)newgdt;
 228
 229         __asm__ __volatile__ (
 230                 "lgdtq %0\n"
 231                 : : "m" (curgdt)
 232                 );
 233 };
 234
 235 static void load_segments(void)
 236 {
 237         __asm__ __volatile__ (
 238                 "\tmovl %0,%%ds\n"
 239                 "\tmovl %0,%%es\n"
 240                 "\tmovl %0,%%ss\n"
 241                 "\tmovl %0,%%fs\n"
 242                 "\tmovl %0,%%gs\n"
 243                 : : "a" (__KERNEL_DS) : "memory"
 244                 );
 245 }
 246
 247 int machine_kexec_prepare(struct kimage *image)
 248 {
 249         unsigned long start_pgtable;
 250         int result;
 251
 252         /* Calculate the offsets */
 253         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 254
 255         /* Setup the identity mapped 64bit page table */
 256         result = init_pgtable(image, start_pgtable);
 257         if (result)
 258                 return result;
 259
 260         return 0;
 261 }
 262
 263 void machine_kexec_cleanup(struct kimage *image)
 264 {
 265         free_transition_pgtable(image);
 266 }
 267
 268 /*
 269  * Do not allocate memory (or fail in any way) in machine_kexec().
 270  * We are past the point of no return, committed to rebooting now.
 271  */
 272 void machine_kexec(struct kimage *image)
 273 {
 274         unsigned long page_list[PAGES_NR];
 275         void *control_page;
 276         int save_ftrace_enabled;
 277
 278 #ifdef CONFIG_KEXEC_JUMP
 279         if (image->preserve_context)
 280                 save_processor_state();
 281 #endif
 282
 283         save_ftrace_enabled = __ftrace_enabled_save();
 284
 285         /* Interrupts aren't acceptable while we reboot */
 286         local_irq_disable();
 287         hw_breakpoint_disable();
 288
 289         if (image->preserve_context) {
 290 #ifdef CONFIG_X86_IO_APIC
 291                 /*
 292                  * We need to put APICs in legacy mode so that we can
 293                  * get timer interrupts in second kernel. kexec/kdump
 294                  * paths already have calls to disable_IO_APIC() in
 295                  * one form or other. kexec jump path also need
 296                  * one.
 297                  */
 298                 disable_IO_APIC();
 299 #endif
 300         }
 301
 302         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 303         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 304
 305         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 306         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 307         page_list[PA_TABLE_PAGE] =
 308           (unsigned long)__pa(page_address(image->control_code_page));
 309
 310         if (image->type == KEXEC_TYPE_DEFAULT)
 311                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 312                                                 << PAGE_SHIFT);
 313
 314         /*
 315          * The segment registers are funny things, they have both a
 316          * visible and an invisible part.  Whenever the visible part is
 317          * set to a specific selector, the invisible part is loaded
 318          * with from a table in memory.  At no other time is the
 319          * descriptor table in memory accessed.
 320          *
 321          * I take advantage of this here by force loading the
 322          * segments, before I zap the gdt with an invalid value.
 323          */
 324         load_segments();
 325         /*
 326          * The gdt & idt are now invalid.
 327          * If you want to load them you must set up your own idt & gdt.
 328          */
 329         set_gdt(phys_to_virt(0), 0);
 330         set_idt(phys_to_virt(0), 0);
 331
 332         /* now call it */
 333         image->start = relocate_kernel((unsigned long)image->head,
 334                                        (unsigned long)page_list,
 335                                        image->start,
 336                                        image->preserve_context);
 337
 338 #ifdef CONFIG_KEXEC_JUMP
 339         if (image->preserve_context)
 340                 restore_processor_state();
 341 #endif
 342
 343         __ftrace_enabled_restore(save_ftrace_enabled);
 344 }
 345
 346 void arch_crash_save_vmcoreinfo(void)
 347 {
 348         VMCOREINFO_SYMBOL(phys_base);
 349         VMCOREINFO_SYMBOL(init_level4_pgt);
 350
 351 #ifdef CONFIG_NUMA
 352         VMCOREINFO_SYMBOL(node_data);
 353         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 354 #endif
 355 }
 356