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_idt(void *newidt, __u16 limit)
  30 {
  31         struct desc_ptr curidt;
  32
  33         /* ia32 supports unaliged loads & stores */
  34         curidt.size    = limit;
  35         curidt.address = (unsigned long)newidt;
  36
  37         load_idt(&curidt);
  38 }
  39
  40
  41 static void set_gdt(void *newgdt, __u16 limit)
  42 {
  43         struct desc_ptr curgdt;
  44
  45         /* ia32 supports unaligned loads & stores */
  46         curgdt.size    = limit;
  47         curgdt.address = (unsigned long)newgdt;
  48
  49         load_gdt(&curgdt);
  50 }
  51
  52 static void load_segments(void)
  53 {
  54 #define __STR(X) #X
  55 #define STR(X) __STR(X)
  56
  57         __asm__ __volatile__ (
  58                 "\tljmp $"STR(__KERNEL_CS)",$1f\n"
  59                 "\t1:\n"
  60                 "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
  61                 "\tmovl %%eax,%%ds\n"
  62                 "\tmovl %%eax,%%es\n"
  63                 "\tmovl %%eax,%%fs\n"
  64                 "\tmovl %%eax,%%gs\n"
  65                 "\tmovl %%eax,%%ss\n"
  66                 : : : "eax", "memory");
  67 #undef STR
  68 #undef __STR
  69 }
  70
  71 static void machine_kexec_free_page_tables(struct kimage *image)
  72 {
  73         free_page((unsigned long)image->arch.pgd);
  74 #ifdef CONFIG_X86_PAE
  75         free_page((unsigned long)image->arch.pmd0);
  76         free_page((unsigned long)image->arch.pmd1);
  77 #endif
  78         free_page((unsigned long)image->arch.pte0);
  79         free_page((unsigned long)image->arch.pte1);
  80 }
  81
  82 static int machine_kexec_alloc_page_tables(struct kimage *image)
  83 {
  84         image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
  85 #ifdef CONFIG_X86_PAE
  86         image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  87         image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  88 #endif
  89         image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  90         image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  91         if (!image->arch.pgd ||
  92 #ifdef CONFIG_X86_PAE
  93             !image->arch.pmd0 || !image->arch.pmd1 ||
  94 #endif
  95             !image->arch.pte0 || !image->arch.pte1) {
  96                 machine_kexec_free_page_tables(image);
  97                 return -ENOMEM;
  98         }
  99         return 0;
 100 }
 101
 102 static void machine_kexec_page_table_set_one(
 103         pgd_t *pgd, pmd_t *pmd, pte_t *pte,
 104         unsigned long vaddr, unsigned long paddr)
 105 {
 106         p4d_t *p4d;
 107         pud_t *pud;
 108
 109         pgd += pgd_index(vaddr);
 110 #ifdef CONFIG_X86_PAE
 111         if (!(pgd_val(*pgd) & _PAGE_PRESENT))
 112                 set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
 113 #endif
 114         p4d = p4d_offset(pgd, vaddr);
 115         pud = pud_offset(p4d, vaddr);
 116         pmd = pmd_offset(pud, vaddr);
 117         if (!(pmd_val(*pmd) & _PAGE_PRESENT))
 118                 set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
 119         pte = pte_offset_kernel(pmd, vaddr);
 120         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
 121 }
 122
 123 static void machine_kexec_prepare_page_tables(struct kimage *image)
 124 {
 125         void *control_page;
 126         pmd_t *pmd = NULL;
 127
 128         control_page = page_address(image->control_code_page);
 129 #ifdef CONFIG_X86_PAE
 130         pmd = image->arch.pmd0;
 131 #endif
 132         machine_kexec_page_table_set_one(
 133                 image->arch.pgd, pmd, image->arch.pte0,
 134                 (unsigned long)control_page, __pa(control_page));
 135 #ifdef CONFIG_X86_PAE
 136         pmd = image->arch.pmd1;
 137 #endif
 138         machine_kexec_page_table_set_one(
 139                 image->arch.pgd, pmd, image->arch.pte1,
 140                 __pa(control_page), __pa(control_page));
 141 }
 142
 143 /*
 144  * A architecture hook called to validate the
 145  * proposed image and prepare the control pages
 146  * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
 147  * have been allocated, but the segments have yet
 148  * been copied into the kernel.
 149  *
 150  * Do what every setup is needed on image and the
 151  * reboot code buffer to allow us to avoid allocations
 152  * later.
 153  *
 154  * - Make control page executable.
 155  * - Allocate page tables
 156  * - Setup page tables
 157  */
 158 int machine_kexec_prepare(struct kimage *image)
 159 {
 160         int error;
 161
 162         set_pages_x(image->control_code_page, 1);
 163         error = machine_kexec_alloc_page_tables(image);
 164         if (error)
 165                 return error;
 166         machine_kexec_prepare_page_tables(image);
 167         return 0;
 168 }
 169
 170 /*
 171  * Undo anything leftover by machine_kexec_prepare
 172  * when an image is freed.
 173  */
 174 void machine_kexec_cleanup(struct kimage *image)
 175 {
 176         set_pages_nx(image->control_code_page, 1);
 177         machine_kexec_free_page_tables(image);
 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         int save_ftrace_enabled;
 189         asmlinkage unsigned long
 190                 (*relocate_kernel_ptr)(unsigned long indirection_page,
 191                                        unsigned long control_page,
 192                                        unsigned long start_address,
 193                                        unsigned int has_pae,
 194                                        unsigned int preserve_context);
 195
 196 #ifdef CONFIG_KEXEC_JUMP
 197         if (image->preserve_context)
 198                 save_processor_state();
 199 #endif
 200
 201         save_ftrace_enabled = __ftrace_enabled_save();
 202
 203         /* Interrupts aren't acceptable while we reboot */
 204         local_irq_disable();
 205         hw_breakpoint_disable();
 206
 207         if (image->preserve_context) {
 208 #ifdef CONFIG_X86_IO_APIC
 209                 /*
 210                  * We need to put APICs in legacy mode so that we can
 211                  * get timer interrupts in second kernel. kexec/kdump
 212                  * paths already have calls to disable_IO_APIC() in
 213                  * one form or other. kexec jump path also need
 214                  * one.
 215                  */
 216                 disable_IO_APIC();
 217 #endif
 218         }
 219
 220         control_page = page_address(image->control_code_page);
 221         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 222
 223         relocate_kernel_ptr = control_page;
 224         page_list[PA_CONTROL_PAGE] = __pa(control_page);
 225         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 226         page_list[PA_PGD] = __pa(image->arch.pgd);
 227
 228         if (image->type == KEXEC_TYPE_DEFAULT)
 229                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 230                                                 << PAGE_SHIFT);
 231
 232         /*
 233          * The segment registers are funny things, they have both a
 234          * visible and an invisible part.  Whenever the visible part is
 235          * set to a specific selector, the invisible part is loaded
 236          * with from a table in memory.  At no other time is the
 237          * descriptor table in memory accessed.
 238          *
 239          * I take advantage of this here by force loading the
 240          * segments, before I zap the gdt with an invalid value.
 241          */
 242         load_segments();
 243         /*
 244          * The gdt & idt are now invalid.
 245          * If you want to load them you must set up your own idt & gdt.
 246          */
 247         set_gdt(phys_to_virt(0), 0);
 248         set_idt(phys_to_virt(0), 0);
 249
 250         /* now call it */
 251         image->start = relocate_kernel_ptr((unsigned long)image->head,
 252                                            (unsigned long)page_list,
 253                                            image->start,
 254                                            boot_cpu_has(X86_FEATURE_PAE),
 255                                            image->preserve_context);
 256
 257 #ifdef CONFIG_KEXEC_JUMP
 258         if (image->preserve_context)
 259                 restore_processor_state();
 260 #endif
 261
 262         __ftrace_enabled_restore(save_ftrace_enabled);
 263 }
 264
 265 void arch_crash_save_vmcoreinfo(void)
 266 {
 267 #ifdef CONFIG_NUMA
 268         VMCOREINFO_SYMBOL(node_data);
 269         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 270 #endif
 271 #ifdef CONFIG_X86_PAE
 272         VMCOREINFO_CONFIG(X86_PAE);
 273 #endif
 274 }
 275