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