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 <linux/ftrace.h>
  15
  16 #include <asm/pgtable.h>
  17 #include <asm/tlbflush.h>
  18 #include <asm/mmu_context.h>
  19 #include <asm/io.h>
  20
  21 #define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
  22 static u64 kexec_pgd[512] PAGE_ALIGNED;
  23 static u64 kexec_pud0[512] PAGE_ALIGNED;
  24 static u64 kexec_pmd0[512] PAGE_ALIGNED;
  25 static u64 kexec_pte0[512] PAGE_ALIGNED;
  26 static u64 kexec_pud1[512] PAGE_ALIGNED;
  27 static u64 kexec_pmd1[512] PAGE_ALIGNED;
  28 static u64 kexec_pte1[512] PAGE_ALIGNED;
  29
  30 static void init_level2_page(pmd_t *level2p, unsigned long addr)
  31 {
  32         unsigned long end_addr;
  33
  34         addr &= PAGE_MASK;
  35         end_addr = addr + PUD_SIZE;
  36         while (addr < end_addr) {
  37                 set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
  38                 addr += PMD_SIZE;
  39         }
  40 }
  41
  42 static int init_level3_page(struct kimage *image, pud_t *level3p,
  43                                 unsigned long addr, unsigned long last_addr)
  44 {
  45         unsigned long end_addr;
  46         int result;
  47
  48         result = 0;
  49         addr &= PAGE_MASK;
  50         end_addr = addr + PGDIR_SIZE;
  51         while ((addr < last_addr) && (addr < end_addr)) {
  52                 struct page *page;
  53                 pmd_t *level2p;
  54
  55                 page = kimage_alloc_control_pages(image, 0);
  56                 if (!page) {
  57                         result = -ENOMEM;
  58                         goto out;
  59                 }
  60                 level2p = (pmd_t *)page_address(page);
  61                 init_level2_page(level2p, addr);
  62                 set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
  63                 addr += PUD_SIZE;
  64         }
  65         /* clear the unused entries */
  66         while (addr < end_addr) {
  67                 pud_clear(level3p++);
  68                 addr += PUD_SIZE;
  69         }
  70 out:
  71         return result;
  72 }
  73
  74
  75 static int init_level4_page(struct kimage *image, pgd_t *level4p,
  76                                 unsigned long addr, unsigned long last_addr)
  77 {
  78         unsigned long end_addr;
  79         int result;
  80
  81         result = 0;
  82         addr &= PAGE_MASK;
  83         end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
  84         while ((addr < last_addr) && (addr < end_addr)) {
  85                 struct page *page;
  86                 pud_t *level3p;
  87
  88                 page = kimage_alloc_control_pages(image, 0);
  89                 if (!page) {
  90                         result = -ENOMEM;
  91                         goto out;
  92                 }
  93                 level3p = (pud_t *)page_address(page);
  94                 result = init_level3_page(image, level3p, addr, last_addr);
  95                 if (result) {
  96                         goto out;
  97                 }
  98                 set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
  99                 addr += PGDIR_SIZE;
 100         }
 101         /* clear the unused entries */
 102         while (addr < end_addr) {
 103                 pgd_clear(level4p++);
 104                 addr += PGDIR_SIZE;
 105         }
 106 out:
 107         return result;
 108 }
 109
 110
 111 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 112 {
 113         pgd_t *level4p;
 114         level4p = (pgd_t *)__va(start_pgtable);
 115         return init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT);
 116 }
 117
 118 static void set_idt(void *newidt, u16 limit)
 119 {
 120         struct desc_ptr curidt;
 121
 122         /* x86-64 supports unaliged loads & stores */
 123         curidt.size    = limit;
 124         curidt.address = (unsigned long)newidt;
 125
 126         __asm__ __volatile__ (
 127                 "lidtq %0\n"
 128                 : : "m" (curidt)
 129                 );
 130 };
 131
 132
 133 static void set_gdt(void *newgdt, u16 limit)
 134 {
 135         struct desc_ptr curgdt;
 136
 137         /* x86-64 supports unaligned loads & stores */
 138         curgdt.size    = limit;
 139         curgdt.address = (unsigned long)newgdt;
 140
 141         __asm__ __volatile__ (
 142                 "lgdtq %0\n"
 143                 : : "m" (curgdt)
 144                 );
 145 };
 146
 147 static void load_segments(void)
 148 {
 149         __asm__ __volatile__ (
 150                 "\tmovl %0,%%ds\n"
 151                 "\tmovl %0,%%es\n"
 152                 "\tmovl %0,%%ss\n"
 153                 "\tmovl %0,%%fs\n"
 154                 "\tmovl %0,%%gs\n"
 155                 : : "a" (__KERNEL_DS) : "memory"
 156                 );
 157 }
 158
 159 int machine_kexec_prepare(struct kimage *image)
 160 {
 161         unsigned long start_pgtable;
 162         int result;
 163
 164         /* Calculate the offsets */
 165         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 166
 167         /* Setup the identity mapped 64bit page table */
 168         result = init_pgtable(image, start_pgtable);
 169         if (result)
 170                 return result;
 171
 172         return 0;
 173 }
 174
 175 void machine_kexec_cleanup(struct kimage *image)
 176 {
 177         return;
 178 }
 179
 180 /*
 181  * Do not allocate memory (or fail in any way) in machine_kexec().
 182  * We are past the point of no return, committed to rebooting now.
 183  */
 184 void machine_kexec(struct kimage *image)
 185 {
 186         unsigned long page_list[PAGES_NR];
 187         void *control_page;
 188
 189         tracer_disable();
 190
 191         /* Interrupts aren't acceptable while we reboot */
 192         local_irq_disable();
 193
 194         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 195         memcpy(control_page, relocate_kernel, PAGE_SIZE);
 196
 197         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 198         page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
 199         page_list[PA_PGD] = virt_to_phys(&kexec_pgd);
 200         page_list[VA_PGD] = (unsigned long)kexec_pgd;
 201         page_list[PA_PUD_0] = virt_to_phys(&kexec_pud0);
 202         page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
 203         page_list[PA_PMD_0] = virt_to_phys(&kexec_pmd0);
 204         page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
 205         page_list[PA_PTE_0] = virt_to_phys(&kexec_pte0);
 206         page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
 207         page_list[PA_PUD_1] = virt_to_phys(&kexec_pud1);
 208         page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
 209         page_list[PA_PMD_1] = virt_to_phys(&kexec_pmd1);
 210         page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
 211         page_list[PA_PTE_1] = virt_to_phys(&kexec_pte1);
 212         page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
 213
 214         page_list[PA_TABLE_PAGE] =
 215           (unsigned long)__pa(page_address(image->control_code_page));
 216
 217         /* The segment registers are funny things, they have both a
 218          * visible and an invisible part.  Whenever the visible part is
 219          * set to a specific selector, the invisible part is loaded
 220          * with from a table in memory.  At no other time is the
 221          * descriptor table in memory accessed.
 222          *
 223          * I take advantage of this here by force loading the
 224          * segments, before I zap the gdt with an invalid value.
 225          */
 226         load_segments();
 227         /* The gdt & idt are now invalid.
 228          * If you want to load them you must set up your own idt & gdt.
 229          */
 230         set_gdt(phys_to_virt(0),0);
 231         set_idt(phys_to_virt(0),0);
 232
 233         /* now call it */
 234         relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
 235                         image->start);
 236 }
 237
 238 void arch_crash_save_vmcoreinfo(void)
 239 {
 240         VMCOREINFO_SYMBOL(phys_base);
 241         VMCOREINFO_SYMBOL(init_level4_pgt);
 242
 243 #ifdef CONFIG_NUMA
 244         VMCOREINFO_SYMBOL(node_data);
 245         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 246 #endif
 247 }
 248