arch/x86/kernel/machine_kexec_32.c

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