LXR linux/arch/i386/kernel/machine

   1/*
   2 * machine_kexec.c - 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 <asm/pgtable.h>
  14#include <asm/pgalloc.h>
  15#include <asm/tlbflush.h>
  16#include <asm/mmu_context.h>
  17#include <asm/io.h>
  18#include <asm/apic.h>
  19#include <asm/cpufeature.h>
  20#include <asm/desc.h>
  21#include <asm/system.h>
  22
  23#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
  24static u32 kexec_pgd[1024] PAGE_ALIGNED;
  25#ifdef CONFIG_X86_PAE
  26static u32 kexec_pmd0[1024] PAGE_ALIGNED;
  27static u32 kexec_pmd1[1024] PAGE_ALIGNED;
  28#endif
  29static u32 kexec_pte0[1024] PAGE_ALIGNED;
  30static u32 kexec_pte1[1024] PAGE_ALIGNED;
  31
  32static void set_idt(void *newidt, __u16 limit)
  33{
  34        struct Xgt_desc_struct curidt;
  35
  36        /* ia32 supports unaliged loads & stores */
  37        curidt.size    = limit;
  38        curidt.address = (unsigned long)newidt;
  39
  40        load_idt(&curidt);
  41};
  42
  43
  44static void set_gdt(void *newgdt, __u16 limit)
  45{
  46        struct Xgt_desc_struct curgdt;
  47
  48        /* ia32 supports unaligned loads & stores */
  49        curgdt.size    = limit;
  50        curgdt.address = (unsigned long)newgdt;
  51
  52        load_gdt(&curgdt);
  53};
  54
  55static void load_segments(void)
  56{
  57#define __STR(X) #X
  58#define STR(X) __STR(X)
  59
  60        __asm__ __volatile__ (
  61                "\tljmp $"STR(__KERNEL_CS)",$1f\n"
  62                "\t1:\n"
  63                "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
  64                "\tmovl %%eax,%%ds\n"
  65                "\tmovl %%eax,%%es\n"
  66                "\tmovl %%eax,%%fs\n"
  67                "\tmovl %%eax,%%gs\n"
  68                "\tmovl %%eax,%%ss\n"
  69                ::: "eax", "memory");
  70#undef STR
  71#undef __STR
  72}
  73
  74/*
  75 * A architecture hook called to validate the
  76 * proposed image and prepare the control pages
  77 * as needed.  The pages for KEXEC_CONTROL_CODE_SIZE
  78 * have been allocated, but the segments have yet
  79 * been copied into the kernel.
  80 *
  81 * Do what every setup is needed on image and the
  82 * reboot code buffer to allow us to avoid allocations
  83 * later.
  84 *
  85 * Currently nothing.
  86 */
  87int machine_kexec_prepare(struct kimage *image)
  88{
  89        return 0;
  90}
  91
  92/*
  93 * Undo anything leftover by machine_kexec_prepare
  94 * when an image is freed.
  95 */
  96void machine_kexec_cleanup(struct kimage *image)
  97{
  98}
  99
 100/*
 101 * Do not allocate memory (or fail in any way) in machine_kexec().
 102 * We are past the point of no return, committed to rebooting now.
 103 */
 104NORET_TYPE void machine_kexec(struct kimage *image)
 105{
 106        unsigned long page_list[PAGES_NR];
 107        void *control_page;
 108
 109        /* Interrupts aren't acceptable while we reboot */
 110        local_irq_disable();
 111
 112        control_page = page_address(image->control_code_page);
 113        memcpy(control_page, relocate_kernel, PAGE_SIZE);
 114
 115        page_list[PA_CONTROL_PAGE] = __pa(control_page);
 116        page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
 117        page_list[PA_PGD] = __pa(kexec_pgd);
 118        page_list[VA_PGD] = (unsigned long)kexec_pgd;
 119#ifdef CONFIG_X86_PAE
 120        page_list[PA_PMD_0] = __pa(kexec_pmd0);
 121        page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
 122        page_list[PA_PMD_1] = __pa(kexec_pmd1);
 123        page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
 124#endif
 125        page_list[PA_PTE_0] = __pa(kexec_pte0);
 126        page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
 127        page_list[PA_PTE_1] = __pa(kexec_pte1);
 128        page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
 129
 130        /* The segment registers are funny things, they have both a
 131         * visible and an invisible part.  Whenever the visible part is
 132         * set to a specific selector, the invisible part is loaded
 133         * with from a table in memory.  At no other time is the
 134         * descriptor table in memory accessed.
 135         *
 136         * I take advantage of this here by force loading the
 137         * segments, before I zap the gdt with an invalid value.
 138         */
 139        load_segments();
 140        /* The gdt & idt are now invalid.
 141         * If you want to load them you must set up your own idt & gdt.
 142         */
 143        set_gdt(phys_to_virt(0),0);
 144        set_idt(phys_to_virt(0),0);
 145
 146        /* now call it */
 147        relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
 148                        image->start, cpu_has_pae);
 149}
 150
 151/* crashkernel=size@addr specifies the location to reserve for
 152 * a crash kernel.  By reserving this memory we guarantee
 153 * that linux never sets it up as a DMA target.
 154 * Useful for holding code to do something appropriate
 155 * after a kernel panic.
 156 */
 157static int __init parse_crashkernel(char *arg)
 158{
 159        unsigned long size, base;
 160        size = memparse(arg, &arg);
 161        if (*arg == '@') {
 162                base = memparse(arg+1, &arg);
 163                /* FIXME: Do I want a sanity check
 164                 * to validate the memory range?
 165                 */
 166                crashk_res.start = base;
 167                crashk_res.end   = base + size - 1;
 168        }
 169        return 0;
 170}
 171early_param("crashkernel", parse_crashkernel);
 172