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/init.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/mmu_context.h>
  23 #include <asm/debugreg.h>
  24
  25 static void free_transition_pgtable(struct kimage *image)
  26 {
  27         free_page((unsigned long)image->arch.pud);
  28         free_page((unsigned long)image->arch.pmd);
  29         free_page((unsigned long)image->arch.pte);
  30 }
  31
  32 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
  33 {
  34         pud_t *pud;
  35         pmd_t *pmd;
  36         pte_t *pte;
  37         unsigned long vaddr, paddr;
  38         int result = -ENOMEM;
  39
  40         vaddr = (unsigned long)relocate_kernel;
  41         paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
  42         pgd += pgd_index(vaddr);
  43         if (!pgd_present(*pgd)) {
  44                 pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
  45                 if (!pud)
  46                         goto err;
  47                 image->arch.pud = pud;
  48                 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
  49         }
  50         pud = pud_offset(pgd, vaddr);
  51         if (!pud_present(*pud)) {
  52                 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  53                 if (!pmd)
  54                         goto err;
  55                 image->arch.pmd = pmd;
  56                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
  57         }
  58         pmd = pmd_offset(pud, vaddr);
  59         if (!pmd_present(*pmd)) {
  60                 pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
  61                 if (!pte)
  62                         goto err;
  63                 image->arch.pte = pte;
  64                 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
  65         }
  66         pte = pte_offset_kernel(pmd, vaddr);
  67         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
  68         return 0;
  69 err:
  70         free_transition_pgtable(image);
  71         return result;
  72 }
  73
  74 static void *alloc_pgt_page(void *data)
  75 {
  76         struct kimage *image = (struct kimage *)data;
  77         struct page *page;
  78         void *p = NULL;
  79
  80         page = kimage_alloc_control_pages(image, 0);
  81         if (page) {
  82                 p = page_address(page);
  83                 clear_page(p);
  84         }
  85
  86         return p;
  87 }
  88
  89 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
  90 {
  91         struct x86_mapping_info info = {
  92                 .alloc_pgt_page = alloc_pgt_page,
  93                 .context        = image,
  94                 .pmd_flag       = __PAGE_KERNEL_LARGE_EXEC,
  95         };
  96         unsigned long mstart, mend;
  97         pgd_t *level4p;
  98         int result;
  99         int i;
 100
 101         level4p = (pgd_t *)__va(start_pgtable);
 102         clear_page(level4p);
 103         for (i = 0; i < nr_pfn_mapped; i++) {
 104                 mstart = pfn_mapped[i].start << PAGE_SHIFT;
 105                 mend   = pfn_mapped[i].end << PAGE_SHIFT;
 106
 107                 result = kernel_ident_mapping_init(&info,
 108                                                  level4p, mstart, mend);
 109                 if (result)
 110                         return result;
 111         }
 112
 113         /*
 114          * segments's mem ranges could be outside 0 ~ max_pfn,
 115          * for example when jump back to original kernel from kexeced kernel.
 116          * or first kernel is booted with user mem map, and second kernel
 117          * could be loaded out of that range.
 118          */
 119         for (i = 0; i < image->nr_segments; i++) {
 120                 mstart = image->segment[i].mem;
 121                 mend   = mstart + image->segment[i].memsz;
 122
 123                 result = kernel_ident_mapping_init(&info,
 124                                                  level4p, mstart, mend);
 125
 126                 if (result)
 127                         return result;
 128         }
 129
 130         return init_transition_pgtable(image, level4p);
 131 }
 132
 133 static void set_idt(void *newidt, u16 limit)
 134 {
 135         struct desc_ptr curidt;
 136
 137         /* x86-64 supports unaliged loads & stores */
 138         curidt.size    = limit;
 139         curidt.address = (unsigned long)newidt;
 140
 141         __asm__ __volatile__ (
 142                 "lidtq %0\n"
 143                 : : "m" (curidt)
 144                 );
 145 };
 146
 147
 148 static void set_gdt(void *newgdt, u16 limit)
 149 {
 150         struct desc_ptr curgdt;
 151
 152         /* x86-64 supports unaligned loads & stores */
 153         curgdt.size    = limit;
 154         curgdt.address = (unsigned long)newgdt;
 155
 156         __asm__ __volatile__ (
 157                 "lgdtq %0\n"
 158                 : : "m" (curgdt)
 159                 );
 160 };
 161
 162 static void load_segments(void)
 163 {
 164         __asm__ __volatile__ (
 165                 "\tmovl %0,%%ds\n"
 166                 "\tmovl %0,%%es\n"
 167                 "\tmovl %0,%%ss\n"
 168                 "\tmovl %0,%%fs\n"
 169                 "\tmovl %0,%%gs\n"
 170                 : : "a" (__KERNEL_DS) : "memory"
 171                 );
 172 }
 173
 174 int machine_kexec_prepare(struct kimage *image)
 175 {
 176         unsigned long start_pgtable;
 177         int result;
 178
 179         /* Calculate the offsets */
 180         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 181
 182         /* Setup the identity mapped 64bit page table */
 183         result = init_pgtable(image, start_pgtable);
 184         if (result)
 185                 return result;
 186
 187         return 0;
 188 }
 189
 190 void machine_kexec_cleanup(struct kimage *image)
 191 {
 192         free_transition_pgtable(image);
 193 }
 194
 195 /*
 196  * Do not allocate memory (or fail in any way) in machine_kexec().
 197  * We are past the point of no return, committed to rebooting now.
 198  */
 199 void machine_kexec(struct kimage *image)
 200 {
 201         unsigned long page_list[PAGES_NR];
 202         void *control_page;
 203         int save_ftrace_enabled;
 204
 205 #ifdef CONFIG_KEXEC_JUMP
 206         if (image->preserve_context)
 207                 save_processor_state();
 208 #endif
 209
 210         save_ftrace_enabled = __ftrace_enabled_save();
 211
 212         /* Interrupts aren't acceptable while we reboot */
 213         local_irq_disable();
 214         hw_breakpoint_disable();
 215
 216         if (image->preserve_context) {
 217 #ifdef CONFIG_X86_IO_APIC
 218                 /*
 219                  * We need to put APICs in legacy mode so that we can
 220                  * get timer interrupts in second kernel. kexec/kdump
 221                  * paths already have calls to disable_IO_APIC() in
 222                  * one form or other. kexec jump path also need
 223                  * one.
 224                  */
 225                 disable_IO_APIC();
 226 #endif
 227         }
 228
 229         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 230         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 231
 232         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 233         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 234         page_list[PA_TABLE_PAGE] =
 235           (unsigned long)__pa(page_address(image->control_code_page));
 236
 237         if (image->type == KEXEC_TYPE_DEFAULT)
 238                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 239                                                 << PAGE_SHIFT);
 240
 241         /*
 242          * The segment registers are funny things, they have both a
 243          * visible and an invisible part.  Whenever the visible part is
 244          * set to a specific selector, the invisible part is loaded
 245          * with from a table in memory.  At no other time is the
 246          * descriptor table in memory accessed.
 247          *
 248          * I take advantage of this here by force loading the
 249          * segments, before I zap the gdt with an invalid value.
 250          */
 251         load_segments();
 252         /*
 253          * The gdt & idt are now invalid.
 254          * If you want to load them you must set up your own idt & gdt.
 255          */
 256         set_gdt(phys_to_virt(0), 0);
 257         set_idt(phys_to_virt(0), 0);
 258
 259         /* now call it */
 260         image->start = relocate_kernel((unsigned long)image->head,
 261                                        (unsigned long)page_list,
 262                                        image->start,
 263                                        image->preserve_context);
 264
 265 #ifdef CONFIG_KEXEC_JUMP
 266         if (image->preserve_context)
 267                 restore_processor_state();
 268 #endif
 269
 270         __ftrace_enabled_restore(save_ftrace_enabled);
 271 }
 272
 273 void arch_crash_save_vmcoreinfo(void)
 274 {
 275         VMCOREINFO_SYMBOL(phys_base);
 276         VMCOREINFO_SYMBOL(init_level4_pgt);
 277
 278 #ifdef CONFIG_NUMA
 279         VMCOREINFO_SYMBOL(node_data);
 280         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 281 #endif
 282         vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
 283                               (unsigned long)&_text - __START_KERNEL);
 284 }
 285