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/reboot.h>
  13 #include <linux/numa.h>
  14 #include <asm/pgtable.h>
  15 #include <asm/tlbflush.h>
  16 #include <asm/mmu_context.h>
  17 #include <asm/io.h>
  18
  19 #define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
  20 static u64 kexec_pgd[512] PAGE_ALIGNED;
  21 static u64 kexec_pud0[512] PAGE_ALIGNED;
  22 static u64 kexec_pmd0[512] PAGE_ALIGNED;
  23 static u64 kexec_pte0[512] PAGE_ALIGNED;
  24 static u64 kexec_pud1[512] PAGE_ALIGNED;
  25 static u64 kexec_pmd1[512] PAGE_ALIGNED;
  26 static u64 kexec_pte1[512] PAGE_ALIGNED;
  27
  28 static void init_level2_page(pmd_t *level2p, unsigned long addr)
  29 {
  30         unsigned long end_addr;
  31
  32         addr &= PAGE_MASK;
  33         end_addr = addr + PUD_SIZE;
  34         while (addr < end_addr) {
  35                 set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
  36                 addr += PMD_SIZE;
  37         }
  38 }
  39
  40 static int init_level3_page(struct kimage *image, pud_t *level3p,
  41                                 unsigned long addr, unsigned long last_addr)
  42 {
  43         unsigned long end_addr;
  44         int result;
  45
  46         result = 0;
  47         addr &= PAGE_MASK;
  48         end_addr = addr + PGDIR_SIZE;
  49         while ((addr < last_addr) && (addr < end_addr)) {
  50                 struct page *page;
  51                 pmd_t *level2p;
  52
  53                 page = kimage_alloc_control_pages(image, 0);
  54                 if (!page) {
  55                         result = -ENOMEM;
  56                         goto out;
  57                 }
  58                 level2p = (pmd_t *)page_address(page);
  59                 init_level2_page(level2p, addr);
  60                 set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
  61                 addr += PUD_SIZE;
  62         }
  63         /* clear the unused entries */
  64         while (addr < end_addr) {
  65                 pud_clear(level3p++);
  66                 addr += PUD_SIZE;
  67         }
  68 out:
  69         return result;
  70 }
  71
  72
  73 static int init_level4_page(struct kimage *image, pgd_t *level4p,
  74                                 unsigned long addr, unsigned long last_addr)
  75 {
  76         unsigned long end_addr;
  77         int result;
  78
  79         result = 0;
  80         addr &= PAGE_MASK;
  81         end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
  82         while ((addr < last_addr) && (addr < end_addr)) {
  83                 struct page *page;
  84                 pud_t *level3p;
  85
  86                 page = kimage_alloc_control_pages(image, 0);
  87                 if (!page) {
  88                         result = -ENOMEM;
  89                         goto out;
  90                 }
  91                 level3p = (pud_t *)page_address(page);
  92                 result = init_level3_page(image, level3p, addr, last_addr);
  93                 if (result) {
  94                         goto out;
  95                 }
  96                 set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
  97                 addr += PGDIR_SIZE;
  98         }
  99         /* clear the unused entries */
 100         while (addr < end_addr) {
 101                 pgd_clear(level4p++);
 102                 addr += PGDIR_SIZE;
 103         }
 104 out:
 105         return result;
 106 }
 107
 108
 109 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 110 {
 111         pgd_t *level4p;
 112         level4p = (pgd_t *)__va(start_pgtable);
 113         return init_level4_page(image, level4p, 0, end_pfn << PAGE_SHIFT);
 114 }
 115
 116 static void set_idt(void *newidt, u16 limit)
 117 {
 118         struct desc_ptr curidt;
 119
 120         /* x86-64 supports unaliged loads & stores */
 121         curidt.size    = limit;
 122         curidt.address = (unsigned long)newidt;
 123
 124         __asm__ __volatile__ (
 125                 "lidtq %0\n"
 126                 : : "m" (curidt)
 127                 );
 128 };
 129
 130
 131 static void set_gdt(void *newgdt, u16 limit)
 132 {
 133         struct desc_ptr curgdt;
 134
 135         /* x86-64 supports unaligned loads & stores */
 136         curgdt.size    = limit;
 137         curgdt.address = (unsigned long)newgdt;
 138
 139         __asm__ __volatile__ (
 140                 "lgdtq %0\n"
 141                 : : "m" (curgdt)
 142                 );
 143 };
 144
 145 static void load_segments(void)
 146 {
 147         __asm__ __volatile__ (
 148                 "\tmovl %0,%%ds\n"
 149                 "\tmovl %0,%%es\n"
 150                 "\tmovl %0,%%ss\n"
 151                 "\tmovl %0,%%fs\n"
 152                 "\tmovl %0,%%gs\n"
 153                 : : "a" (__KERNEL_DS) : "memory"
 154                 );
 155 }
 156
 157 int machine_kexec_prepare(struct kimage *image)
 158 {
 159         unsigned long start_pgtable;
 160         int result;
 161
 162         /* Calculate the offsets */
 163         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 164
 165         /* Setup the identity mapped 64bit page table */
 166         result = init_pgtable(image, start_pgtable);
 167         if (result)
 168                 return result;
 169
 170         return 0;
 171 }
 172
 173 void machine_kexec_cleanup(struct kimage *image)
 174 {
 175         return;
 176 }
 177
 178 /*
 179  * Do not allocate memory (or fail in any way) in machine_kexec().
 180  * We are past the point of no return, committed to rebooting now.
 181  */
 182 NORET_TYPE void machine_kexec(struct kimage *image)
 183 {
 184         unsigned long page_list[PAGES_NR];
 185         void *control_page;
 186
 187         /* Interrupts aren't acceptable while we reboot */
 188         local_irq_disable();
 189
 190         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 191         memcpy(control_page, relocate_kernel, PAGE_SIZE);
 192
 193         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 194         page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
 195         page_list[PA_PGD] = virt_to_phys(&kexec_pgd);
 196         page_list[VA_PGD] = (unsigned long)kexec_pgd;
 197         page_list[PA_PUD_0] = virt_to_phys(&kexec_pud0);
 198         page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
 199         page_list[PA_PMD_0] = virt_to_phys(&kexec_pmd0);
 200         page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
 201         page_list[PA_PTE_0] = virt_to_phys(&kexec_pte0);
 202         page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
 203         page_list[PA_PUD_1] = virt_to_phys(&kexec_pud1);
 204         page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
 205         page_list[PA_PMD_1] = virt_to_phys(&kexec_pmd1);
 206         page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
 207         page_list[PA_PTE_1] = virt_to_phys(&kexec_pte1);
 208         page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
 209
 210         page_list[PA_TABLE_PAGE] =
 211           (unsigned long)__pa(page_address(image->control_code_page));
 212
 213         /* The segment registers are funny things, they have both a
 214          * visible and an invisible part.  Whenever the visible part is
 215          * set to a specific selector, the invisible part is loaded
 216          * with from a table in memory.  At no other time is the
 217          * descriptor table in memory accessed.
 218          *
 219          * I take advantage of this here by force loading the
 220          * segments, before I zap the gdt with an invalid value.
 221          */
 222         load_segments();
 223         /* The gdt & idt are now invalid.
 224          * If you want to load them you must set up your own idt & gdt.
 225          */
 226         set_gdt(phys_to_virt(0),0);
 227         set_idt(phys_to_virt(0),0);
 228
 229         /* now call it */
 230         relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
 231                         image->start);
 232 }
 233
 234 void arch_crash_save_vmcoreinfo(void)
 235 {
 236         VMCOREINFO_SYMBOL(init_level4_pgt);
 237 }
 238