arch/x86/kernel/machine_kexec_32.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/delay.h>
  12 #include <linux/numa.h>
  13 #include <linux/ftrace.h>
  14 #include <linux/suspend.h>
  15 #include <linux/gfp.h>
  16 #include <linux/io.h>
  17
  18 #include <asm/pgtable.h>
  19 #include <asm/pgalloc.h>
  20 #include <asm/tlbflush.h>
  21 #include <asm/mmu_context.h>
  22 #include <asm/apic.h>
  23 #include <asm/io_apic.h>
  24 #include <asm/cpufeature.h>
  25 #include <asm/desc.h>
  26 #include <asm/set_memory.h>
  27 #include <asm/debugreg.h>
  28
  29 static void set_gdt(void *newgdt, __u16 limit)
  30 {
  31         struct desc_ptr curgdt;
  32
  33         /* ia32 supports unaligned loads & stores */
  34         curgdt.size    = limit;
  35         curgdt.address = (unsigned long)newgdt;
  36
  37         load_gdt(&curgdt);
  38 }
  39
  40 static void load_segments(void)
  41 {
  42 #define __STR(X) #X
  43 #define STR(X) __STR(X)
  44
  45         __asm__ __volatile__ (
  46                 "\tljmp $"STR(__KERNEL_CS)",$1f\n"
  47                 "\t1:\n"
  48                 "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
  49                 "\tmovl %%eax,%%ds\n"
  50                 "\tmovl %%eax,%%es\n"
  51                 "\tmovl %%eax,%%ss\n"
  52                 : : : "eax", "memory");
  53 #undef STR
  54 #undef __STR
  55 }
  56
  57 static void machine_kexec_free_page_tables(struct kimage *image)
  58 {
  59         free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER);
  60         image->arch.pgd = NULL;
  61 #ifdef CONFIG_X86_PAE
  62         free_page((unsigned long)image->arch.pmd0);
  63         image->arch.pmd0 = NULL;
  64         free_page((unsigned long)image->arch.pmd1);
  65         image->arch.pmd1 = NULL;
  66 #endif
  67         free_page((unsigned long)image->arch.pte0);
  68         image->arch.pte0 = NULL;
  69         free_page((unsigned long)image->arch.pte1);
  70         image->arch.pte1 = NULL;
  71 }
  72
  73 static int machine_kexec_alloc_page_tables(struct kimage *image)
  74 {
  75         image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
  76                                                     PGD_ALLOCATION_ORDER);
  77 #ifdef CONFIG_X86_PAE
  78         image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  79         image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  80 #endif
  81         image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  82         image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  83         if (!image->arch.pgd ||
  84 #ifdef CONFIG_X86_PAE
  85             !image->arch.pmd0 || !image->arch.pmd1 ||
  86 #endif
  87             !image->arch.pte0 || !image->arch.pte1) {
  88                 return -ENOMEM;
  89         }
  90         return 0;
  91 }
  92
  93 static void machine_kexec_page_table_set_one(
  94         pgd_t *pgd, pmd_t *pmd, pte_t *pte,
  95         unsigned long vaddr, unsigned long paddr)
  96 {
  97         p4d_t *p4d;
  98         pud_t *pud;
  99
 100         pgd += pgd_index(vaddr);
 101 #ifdef CONFIG_X86_PAE
 102         if (!(pgd_val(*pgd) & _PAGE_PRESENT))
 103                 set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
 104 #endif
 105         p4d = p4d_offset(pgd, vaddr);
 106         pud = pud_offset(p4d, vaddr);
 107         pmd = pmd_offset(pud, vaddr);
 108         if (!(pmd_val(*pmd) & _PAGE_PRESENT))
 109                 set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
 110         pte = pte_offset_kernel(pmd, vaddr);
 111         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
 112 }
 113
 114 static void machine_kexec_prepare_page_tables(struct kimage *image)
 115 {
 116         void *control_page;
 117         pmd_t *pmd = NULL;
 118
 119         control_page = page_address(image->control_code_page);
 120 #ifdef CONFIG_X86_PAE
 121         pmd = image->arch.pmd0;
 122 #endif
 123         machine_kexec_page_table_set_one(
 124                 image->arch.pgd, pmd, image->arch.pte0,
 125                 (unsigned long)control_page, __pa(control_page));
 126 #ifdef CONFIG_X86_PAE
 127         pmd = image->arch.pmd1;
 128 #endif
 129         machine_kexec_page_table_set_one(
 130                 image->arch.pgd, pmd, image->arch.pte1,
 131                 __pa(control_page), __pa(control_page));
 132 }
 133
 134 /*
 135  * A architecture hook called to validate the
 136  * proposed image and prepare the control pages
 137  * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
 138  * have been allocated, but the segments have yet
 139  * been copied into the kernel.
 140  *
 141  * Do what every setup is needed on image and the
 142  * reboot code buffer to allow us to avoid allocations
 143  * later.
 144  *
 145  * - Make control page executable.
 146  * - Allocate page tables
 147  * - Setup page tables
 148  */
 149 int machine_kexec_prepare(struct kimage *image)
 150 {
 151         int error;
 152
 153         set_pages_x(image->control_code_page, 1);
 154         error = machine_kexec_alloc_page_tables(image);
 155         if (error)
 156                 return error;
 157         machine_kexec_prepare_page_tables(image);
 158         return 0;
 159 }
 160
 161 /*
 162  * Undo anything leftover by machine_kexec_prepare
 163  * when an image is freed.
 164  */
 165 void machine_kexec_cleanup(struct kimage *image)
 166 {
 167         set_pages_nx(image->control_code_page, 1);
 168         machine_kexec_free_page_tables(image);
 169 }
 170
 171 /*
 172  * Do not allocate memory (or fail in any way) in machine_kexec().
 173  * We are past the point of no return, committed to rebooting now.
 174  */
 175 void machine_kexec(struct kimage *image)
 176 {
 177         unsigned long page_list[PAGES_NR];
 178         void *control_page;
 179         int save_ftrace_enabled;
 180         asmlinkage unsigned long
 181                 (*relocate_kernel_ptr)(unsigned long indirection_page,
 182                                        unsigned long control_page,
 183                                        unsigned long start_address,
 184                                        unsigned int has_pae,
 185                                        unsigned int preserve_context);
 186
 187 #ifdef CONFIG_KEXEC_JUMP
 188         if (image->preserve_context)
 189                 save_processor_state();
 190 #endif
 191
 192         save_ftrace_enabled = __ftrace_enabled_save();
 193
 194         /* Interrupts aren't acceptable while we reboot */
 195         local_irq_disable();
 196         hw_breakpoint_disable();
 197
 198         if (image->preserve_context) {
 199 #ifdef CONFIG_X86_IO_APIC
 200                 /*
 201                  * We need to put APICs in legacy mode so that we can
 202                  * get timer interrupts in second kernel. kexec/kdump
 203                  * paths already have calls to restore_boot_irq_mode()
 204                  * in one form or other. kexec jump path also need one.
 205                  */
 206                 clear_IO_APIC();
 207                 restore_boot_irq_mode();
 208 #endif
 209         }
 210
 211         control_page = page_address(image->control_code_page);
 212         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 213
 214         relocate_kernel_ptr = control_page;
 215         page_list[PA_CONTROL_PAGE] = __pa(control_page);
 216         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 217         page_list[PA_PGD] = __pa(image->arch.pgd);
 218
 219         if (image->type == KEXEC_TYPE_DEFAULT)
 220                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 221                                                 << PAGE_SHIFT);
 222
 223         /*
 224          * The segment registers are funny things, they have both a
 225          * visible and an invisible part.  Whenever the visible part is
 226          * set to a specific selector, the invisible part is loaded
 227          * with from a table in memory.  At no other time is the
 228          * descriptor table in memory accessed.
 229          *
 230          * I take advantage of this here by force loading the
 231          * segments, before I zap the gdt with an invalid value.
 232          */
 233         load_segments();
 234         /*
 235          * The gdt & idt are now invalid.
 236          * If you want to load them you must set up your own idt & gdt.
 237          */
 238         idt_invalidate(phys_to_virt(0));
 239         set_gdt(phys_to_virt(0), 0);
 240
 241         /* now call it */
 242         image->start = relocate_kernel_ptr((unsigned long)image->head,
 243                                            (unsigned long)page_list,
 244                                            image->start,
 245                                            boot_cpu_has(X86_FEATURE_PAE),
 246                                            image->preserve_context);
 247
 248 #ifdef CONFIG_KEXEC_JUMP
 249         if (image->preserve_context)
 250                 restore_processor_state();
 251 #endif
 252
 253         __ftrace_enabled_restore(save_ftrace_enabled);
 254 }
 255
 256 void arch_crash_save_vmcoreinfo(void)
 257 {
 258 #ifdef CONFIG_NUMA
 259         VMCOREINFO_SYMBOL(node_data);
 260         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 261 #endif
 262 #ifdef CONFIG_X86_PAE
 263         VMCOREINFO_CONFIG(X86_PAE);
 264 #endif
 265 }
 266