root/arch/x86/kernel/machine_kexec_32.c

DEFINITIONS

1. set_gdt
2. load_segments
3. machine_kexec_free_page_tables
4. machine_kexec_alloc_page_tables
5. machine_kexec_page_table_set_one
6. machine_kexec_prepare_page_tables
7. machine_kexec_prepare
8. machine_kexec_cleanup
9. machine_kexec
10. arch_crash_save_vmcoreinfo

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * handle transition of Linux booting another kernel
   4  * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
   5  */
   6 
   7 #include <linux/mm.h>
   8 #include <linux/kexec.h>
   9 #include <linux/delay.h>
  10 #include <linux/numa.h>
  11 #include <linux/ftrace.h>
  12 #include <linux/suspend.h>
  13 #include <linux/gfp.h>
  14 #include <linux/io.h>
  15 
  16 #include <asm/pgtable.h>
  17 #include <asm/pgalloc.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/mmu_context.h>
  20 #include <asm/apic.h>
  21 #include <asm/io_apic.h>
  22 #include <asm/cpufeature.h>
  23 #include <asm/desc.h>
  24 #include <asm/set_memory.h>
  25 #include <asm/debugreg.h>
  26 
  27 static void set_gdt(void *newgdt, __u16 limit)
  28 {
  29         struct desc_ptr curgdt;
  30 
  31         /* ia32 supports unaligned loads & stores */
  32         curgdt.size    = limit;
  33         curgdt.address = (unsigned long)newgdt;
  34 
  35         load_gdt(&curgdt);
  36 }
  37 
  38 static void load_segments(void)
  39 {
  40 #define __STR(X) #X
  41 #define STR(X) __STR(X)
  42 
  43         __asm__ __volatile__ (
  44                 "\tljmp $"STR(__KERNEL_CS)",$1f\n"
  45                 "\t1:\n"
  46                 "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
  47                 "\tmovl %%eax,%%ds\n"
  48                 "\tmovl %%eax,%%es\n"
  49                 "\tmovl %%eax,%%ss\n"
  50                 : : : "eax", "memory");
  51 #undef STR
  52 #undef __STR
  53 }
  54 
  55 static void machine_kexec_free_page_tables(struct kimage *image)
  56 {
  57         free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER);
  58         image->arch.pgd = NULL;
  59 #ifdef CONFIG_X86_PAE
  60         free_page((unsigned long)image->arch.pmd0);
  61         image->arch.pmd0 = NULL;
  62         free_page((unsigned long)image->arch.pmd1);
  63         image->arch.pmd1 = NULL;
  64 #endif
  65         free_page((unsigned long)image->arch.pte0);
  66         image->arch.pte0 = NULL;
  67         free_page((unsigned long)image->arch.pte1);
  68         image->arch.pte1 = NULL;
  69 }
  70 
  71 static int machine_kexec_alloc_page_tables(struct kimage *image)
  72 {
  73         image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
  74                                                     PGD_ALLOCATION_ORDER);
  75 #ifdef CONFIG_X86_PAE
  76         image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  77         image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  78 #endif
  79         image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  80         image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  81         if (!image->arch.pgd ||
  82 #ifdef CONFIG_X86_PAE
  83             !image->arch.pmd0 || !image->arch.pmd1 ||
  84 #endif
  85             !image->arch.pte0 || !image->arch.pte1) {
  86                 return -ENOMEM;
  87         }
  88         return 0;
  89 }
  90 
  91 static void machine_kexec_page_table_set_one(
  92         pgd_t *pgd, pmd_t *pmd, pte_t *pte,
  93         unsigned long vaddr, unsigned long paddr)
  94 {
  95         p4d_t *p4d;
  96         pud_t *pud;
  97 
  98         pgd += pgd_index(vaddr);
  99 #ifdef CONFIG_X86_PAE
 100         if (!(pgd_val(*pgd) & _PAGE_PRESENT))
 101                 set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
 102 #endif
 103         p4d = p4d_offset(pgd, vaddr);
 104         pud = pud_offset(p4d, vaddr);
 105         pmd = pmd_offset(pud, vaddr);
 106         if (!(pmd_val(*pmd) & _PAGE_PRESENT))
 107                 set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
 108         pte = pte_offset_kernel(pmd, vaddr);
 109         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
 110 }
 111 
 112 static void machine_kexec_prepare_page_tables(struct kimage *image)
 113 {
 114         void *control_page;
 115         pmd_t *pmd = NULL;
 116 
 117         control_page = page_address(image->control_code_page);
 118 #ifdef CONFIG_X86_PAE
 119         pmd = image->arch.pmd0;
 120 #endif
 121         machine_kexec_page_table_set_one(
 122                 image->arch.pgd, pmd, image->arch.pte0,
 123                 (unsigned long)control_page, __pa(control_page));
 124 #ifdef CONFIG_X86_PAE
 125         pmd = image->arch.pmd1;
 126 #endif
 127         machine_kexec_page_table_set_one(
 128                 image->arch.pgd, pmd, image->arch.pte1,
 129                 __pa(control_page), __pa(control_page));
 130 }
 131 
 132 /*
 133  * A architecture hook called to validate the
 134  * proposed image and prepare the control pages
 135  * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
 136  * have been allocated, but the segments have yet
 137  * been copied into the kernel.
 138  *
 139  * Do what every setup is needed on image and the
 140  * reboot code buffer to allow us to avoid allocations
 141  * later.
 142  *
 143  * - Make control page executable.
 144  * - Allocate page tables
 145  * - Setup page tables
 146  */
 147 int machine_kexec_prepare(struct kimage *image)
 148 {
 149         int error;
 150 
 151         set_memory_x((unsigned long)page_address(image->control_code_page), 1);
 152         error = machine_kexec_alloc_page_tables(image);
 153         if (error)
 154                 return error;
 155         machine_kexec_prepare_page_tables(image);
 156         return 0;
 157 }
 158 
 159 /*
 160  * Undo anything leftover by machine_kexec_prepare
 161  * when an image is freed.
 162  */
 163 void machine_kexec_cleanup(struct kimage *image)
 164 {
 165         set_memory_nx((unsigned long)page_address(image->control_code_page), 1);
 166         machine_kexec_free_page_tables(image);
 167 }
 168 
 169 /*
 170  * Do not allocate memory (or fail in any way) in machine_kexec().
 171  * We are past the point of no return, committed to rebooting now.
 172  */
 173 void machine_kexec(struct kimage *image)
 174 {
 175         unsigned long page_list[PAGES_NR];
 176         void *control_page;
 177         int save_ftrace_enabled;
 178         asmlinkage unsigned long
 179                 (*relocate_kernel_ptr)(unsigned long indirection_page,
 180                                        unsigned long control_page,
 181                                        unsigned long start_address,
 182                                        unsigned int has_pae,
 183                                        unsigned int preserve_context);
 184 
 185 #ifdef CONFIG_KEXEC_JUMP
 186         if (image->preserve_context)
 187                 save_processor_state();
 188 #endif
 189 
 190         save_ftrace_enabled = __ftrace_enabled_save();
 191 
 192         /* Interrupts aren't acceptable while we reboot */
 193         local_irq_disable();
 194         hw_breakpoint_disable();
 195 
 196         if (image->preserve_context) {
 197 #ifdef CONFIG_X86_IO_APIC
 198                 /*
 199                  * We need to put APICs in legacy mode so that we can
 200                  * get timer interrupts in second kernel. kexec/kdump
 201                  * paths already have calls to restore_boot_irq_mode()
 202                  * in one form or other. kexec jump path also need one.
 203                  */
 204                 clear_IO_APIC();
 205                 restore_boot_irq_mode();
 206 #endif
 207         }
 208 
 209         control_page = page_address(image->control_code_page);
 210         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 211 
 212         relocate_kernel_ptr = control_page;
 213         page_list[PA_CONTROL_PAGE] = __pa(control_page);
 214         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 215         page_list[PA_PGD] = __pa(image->arch.pgd);
 216 
 217         if (image->type == KEXEC_TYPE_DEFAULT)
 218                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 219                                                 << PAGE_SHIFT);
 220 
 221         /*
 222          * The segment registers are funny things, they have both a
 223          * visible and an invisible part.  Whenever the visible part is
 224          * set to a specific selector, the invisible part is loaded
 225          * with from a table in memory.  At no other time is the
 226          * descriptor table in memory accessed.
 227          *
 228          * I take advantage of this here by force loading the
 229          * segments, before I zap the gdt with an invalid value.
 230          */
 231         load_segments();
 232         /*
 233          * The gdt & idt are now invalid.
 234          * If you want to load them you must set up your own idt & gdt.
 235          */
 236         idt_invalidate(phys_to_virt(0));
 237         set_gdt(phys_to_virt(0), 0);
 238 
 239         /* now call it */
 240         image->start = relocate_kernel_ptr((unsigned long)image->head,
 241                                            (unsigned long)page_list,
 242                                            image->start,
 243                                            boot_cpu_has(X86_FEATURE_PAE),
 244                                            image->preserve_context);
 245 
 246 #ifdef CONFIG_KEXEC_JUMP
 247         if (image->preserve_context)
 248                 restore_processor_state();
 249 #endif
 250 
 251         __ftrace_enabled_restore(save_ftrace_enabled);
 252 }
 253 
 254 void arch_crash_save_vmcoreinfo(void)
 255 {
 256 #ifdef CONFIG_NUMA
 257         VMCOREINFO_SYMBOL(node_data);
 258         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 259 #endif
 260 #ifdef CONFIG_X86_PAE
 261         VMCOREINFO_CONFIG(X86_PAE);
 262 #endif
 263 }
 264