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