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/init.h>
  13 #include <linux/numa.h>
  14 #include <linux/ftrace.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/io.h>
  21 #include <asm/apic.h>
  22 #include <asm/cpufeature.h>
  23 #include <asm/desc.h>
  24 #include <asm/system.h>
  25 #include <asm/cacheflush.h>
  26
  27 #define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
  28 static u32 kexec_pgd[1024] PAGE_ALIGNED;
  29 #ifdef CONFIG_X86_PAE
  30 static u32 kexec_pmd0[1024] PAGE_ALIGNED;
  31 static u32 kexec_pmd1[1024] PAGE_ALIGNED;
  32 #endif
  33 static u32 kexec_pte0[1024] PAGE_ALIGNED;
  34 static u32 kexec_pte1[1024] PAGE_ALIGNED;
  35
  36 static void set_idt(void *newidt, __u16 limit)
  37 {
  38         struct desc_ptr curidt;
  39
  40         /* ia32 supports unaliged loads & stores */
  41         curidt.size    = limit;
  42         curidt.address = (unsigned long)newidt;
  43
  44         load_idt(&curidt);
  45 }
  46
  47
  48 static void set_gdt(void *newgdt, __u16 limit)
  49 {
  50         struct desc_ptr curgdt;
  51
  52         /* ia32 supports unaligned loads & stores */
  53         curgdt.size    = limit;
  54         curgdt.address = (unsigned long)newgdt;
  55
  56         load_gdt(&curgdt);
  57 }
  58
  59 static void load_segments(void)
  60 {
  61 #define __STR(X) #X
  62 #define STR(X) __STR(X)
  63
  64         __asm__ __volatile__ (
  65                 "\tljmp $"STR(__KERNEL_CS)",$1f\n"
  66                 "\t1:\n"
  67                 "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
  68                 "\tmovl %%eax,%%ds\n"
  69                 "\tmovl %%eax,%%es\n"
  70                 "\tmovl %%eax,%%fs\n"
  71                 "\tmovl %%eax,%%gs\n"
  72                 "\tmovl %%eax,%%ss\n"
  73                 ::: "eax", "memory");
  74 #undef STR
  75 #undef __STR
  76 }
  77
  78 /*
  79  * A architecture hook called to validate the
  80  * proposed image and prepare the control pages
  81  * as needed.  The pages for KEXEC_CONTROL_CODE_SIZE
  82  * have been allocated, but the segments have yet
  83  * been copied into the kernel.
  84  *
  85  * Do what every setup is needed on image and the
  86  * reboot code buffer to allow us to avoid allocations
  87  * later.
  88  *
  89  * Make control page executable.
  90  */
  91 int machine_kexec_prepare(struct kimage *image)
  92 {
  93         if (nx_enabled)
  94                 set_pages_x(image->control_code_page, 1);
  95         return 0;
  96 }
  97
  98 /*
  99  * Undo anything leftover by machine_kexec_prepare
 100  * when an image is freed.
 101  */
 102 void machine_kexec_cleanup(struct kimage *image)
 103 {
 104         if (nx_enabled)
 105                 set_pages_nx(image->control_code_page, 1);
 106 }
 107
 108 /*
 109  * Do not allocate memory (or fail in any way) in machine_kexec().
 110  * We are past the point of no return, committed to rebooting now.
 111  */
 112 void machine_kexec(struct kimage *image)
 113 {
 114         unsigned long page_list[PAGES_NR];
 115         void *control_page;
 116         asmlinkage unsigned long
 117                 (*relocate_kernel_ptr)(unsigned long indirection_page,
 118                                        unsigned long control_page,
 119                                        unsigned long start_address,
 120                                        unsigned int has_pae,
 121                                        unsigned int preserve_context);
 122
 123         tracer_disable();
 124
 125         /* Interrupts aren't acceptable while we reboot */
 126         local_irq_disable();
 127
 128         control_page = page_address(image->control_code_page);
 129         memcpy(control_page, relocate_kernel, PAGE_SIZE/2);
 130
 131         relocate_kernel_ptr = control_page;
 132         page_list[PA_CONTROL_PAGE] = __pa(control_page);
 133         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 134         page_list[PA_PGD] = __pa(kexec_pgd);
 135         page_list[VA_PGD] = (unsigned long)kexec_pgd;
 136 #ifdef CONFIG_X86_PAE
 137         page_list[PA_PMD_0] = __pa(kexec_pmd0);
 138         page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
 139         page_list[PA_PMD_1] = __pa(kexec_pmd1);
 140         page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
 141 #endif
 142         page_list[PA_PTE_0] = __pa(kexec_pte0);
 143         page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
 144         page_list[PA_PTE_1] = __pa(kexec_pte1);
 145         page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
 146         page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) << PAGE_SHIFT);
 147
 148         /* The segment registers are funny things, they have both a
 149          * visible and an invisible part.  Whenever the visible part is
 150          * set to a specific selector, the invisible part is loaded
 151          * with from a table in memory.  At no other time is the
 152          * descriptor table in memory accessed.
 153          *
 154          * I take advantage of this here by force loading the
 155          * segments, before I zap the gdt with an invalid value.
 156          */
 157         load_segments();
 158         /* The gdt & idt are now invalid.
 159          * If you want to load them you must set up your own idt & gdt.
 160          */
 161         set_gdt(phys_to_virt(0),0);
 162         set_idt(phys_to_virt(0),0);
 163
 164         /* now call it */
 165         image->start = relocate_kernel_ptr((unsigned long)image->head,
 166                                            (unsigned long)page_list,
 167                                            image->start, cpu_has_pae,
 168                                            image->preserve_context);
 169 }
 170
 171 void arch_crash_save_vmcoreinfo(void)
 172 {
 173 #ifdef CONFIG_NUMA
 174         VMCOREINFO_SYMBOL(node_data);
 175         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 176 #endif
 177 #ifdef CONFIG_X86_PAE
 178         VMCOREINFO_CONFIG(X86_PAE);
 179 #endif
 180 }
 181