Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
machine_kexec_32.c
Go to the documentation of this file.
1 /*
2  * handle transition of Linux booting another kernel
3  * Copyright (C) 2002-2005 Eric Biederman <[email protected]>
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 #include <linux/suspend.h>
16 #include <linux/gfp.h>
17 #include <linux/io.h>
18 
19 #include <asm/pgtable.h>
20 #include <asm/pgalloc.h>
21 #include <asm/tlbflush.h>
22 #include <asm/mmu_context.h>
23 #include <asm/apic.h>
24 #include <asm/cpufeature.h>
25 #include <asm/desc.h>
26 #include <asm/cacheflush.h>
27 #include <asm/debugreg.h>
28 
29 static void set_idt(void *newidt, __u16 limit)
30 {
31  struct desc_ptr curidt;
32 
33  /* ia32 supports unaliged loads & stores */
34  curidt.size = limit;
35  curidt.address = (unsigned long)newidt;
36 
37  load_idt(&curidt);
38 }
39 
40 
41 static void set_gdt(void *newgdt, __u16 limit)
42 {
43  struct desc_ptr curgdt;
44 
45  /* ia32 supports unaligned loads & stores */
46  curgdt.size = limit;
47  curgdt.address = (unsigned long)newgdt;
48 
49  load_gdt(&curgdt);
50 }
51 
52 static void load_segments(void)
53 {
54 #define __STR(X) #X
55 #define STR(X) __STR(X)
56 
57  __asm__ __volatile__ (
58  "\tljmp $"STR(__KERNEL_CS)",$1f\n"
59  "\t1:\n"
60  "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
61  "\tmovl %%eax,%%ds\n"
62  "\tmovl %%eax,%%es\n"
63  "\tmovl %%eax,%%fs\n"
64  "\tmovl %%eax,%%gs\n"
65  "\tmovl %%eax,%%ss\n"
66  : : : "eax", "memory");
67 #undef STR
68 #undef __STR
69 }
70 
71 static void machine_kexec_free_page_tables(struct kimage *image)
72 {
73  free_page((unsigned long)image->arch.pgd);
74 #ifdef CONFIG_X86_PAE
75  free_page((unsigned long)image->arch.pmd0);
76  free_page((unsigned long)image->arch.pmd1);
77 #endif
78  free_page((unsigned long)image->arch.pte0);
79  free_page((unsigned long)image->arch.pte1);
80 }
81 
82 static int machine_kexec_alloc_page_tables(struct kimage *image)
83 {
84  image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
85 #ifdef CONFIG_X86_PAE
86  image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
87  image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
88 #endif
89  image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
90  image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
91  if (!image->arch.pgd ||
92 #ifdef CONFIG_X86_PAE
93  !image->arch.pmd0 || !image->arch.pmd1 ||
94 #endif
95  !image->arch.pte0 || !image->arch.pte1) {
96  machine_kexec_free_page_tables(image);
97  return -ENOMEM;
98  }
99  return 0;
100 }
101 
102 static void machine_kexec_page_table_set_one(
103  pgd_t *pgd, pmd_t *pmd, pte_t *pte,
104  unsigned long vaddr, unsigned long paddr)
105 {
106  pud_t *pud;
107 
108  pgd += pgd_index(vaddr);
109 #ifdef CONFIG_X86_PAE
110  if (!(pgd_val(*pgd) & _PAGE_PRESENT))
111  set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
112 #endif
113  pud = pud_offset(pgd, vaddr);
114  pmd = pmd_offset(pud, vaddr);
115  if (!(pmd_val(*pmd) & _PAGE_PRESENT))
116  set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
117  pte = pte_offset_kernel(pmd, vaddr);
118  set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
119 }
120 
121 static void machine_kexec_prepare_page_tables(struct kimage *image)
122 {
123  void *control_page;
124  pmd_t *pmd = NULL;
125 
126  control_page = page_address(image->control_code_page);
127 #ifdef CONFIG_X86_PAE
128  pmd = image->arch.pmd0;
129 #endif
130  machine_kexec_page_table_set_one(
131  image->arch.pgd, pmd, image->arch.pte0,
132  (unsigned long)control_page, __pa(control_page));
133 #ifdef CONFIG_X86_PAE
134  pmd = image->arch.pmd1;
135 #endif
136  machine_kexec_page_table_set_one(
137  image->arch.pgd, pmd, image->arch.pte1,
138  __pa(control_page), __pa(control_page));
139 }
140 
141 /*
142  * A architecture hook called to validate the
143  * proposed image and prepare the control pages
144  * as needed. The pages for KEXEC_CONTROL_PAGE_SIZE
145  * have been allocated, but the segments have yet
146  * been copied into the kernel.
147  *
148  * Do what every setup is needed on image and the
149  * reboot code buffer to allow us to avoid allocations
150  * later.
151  *
152  * - Make control page executable.
153  * - Allocate page tables
154  * - Setup page tables
155  */
156 int machine_kexec_prepare(struct kimage *image)
157 {
158  int error;
159 
160  set_pages_x(image->control_code_page, 1);
161  error = machine_kexec_alloc_page_tables(image);
162  if (error)
163  return error;
164  machine_kexec_prepare_page_tables(image);
165  return 0;
166 }
167 
168 /*
169  * Undo anything leftover by machine_kexec_prepare
170  * when an image is freed.
171  */
172 void machine_kexec_cleanup(struct kimage *image)
173 {
174  set_pages_nx(image->control_code_page, 1);
175  machine_kexec_free_page_tables(image);
176 }
177 
178 /*
179  * Do not allocate memory (or fail in any way) in machine_kexec().
180  * We are past the point of no return, committed to rebooting now.
181  */
182 void machine_kexec(struct kimage *image)
183 {
184  unsigned long page_list[PAGES_NR];
185  void *control_page;
186  int save_ftrace_enabled;
187  asmlinkage unsigned long
188  (*relocate_kernel_ptr)(unsigned long indirection_page,
189  unsigned long control_page,
190  unsigned long start_address,
191  unsigned int has_pae,
192  unsigned int preserve_context);
193 
194 #ifdef CONFIG_KEXEC_JUMP
195  if (image->preserve_context)
197 #endif
198 
199  save_ftrace_enabled = __ftrace_enabled_save();
200 
201  /* Interrupts aren't acceptable while we reboot */
203  hw_breakpoint_disable();
204 
205  if (image->preserve_context) {
206 #ifdef CONFIG_X86_IO_APIC
207  /*
208  * We need to put APICs in legacy mode so that we can
209  * get timer interrupts in second kernel. kexec/kdump
210  * paths already have calls to disable_IO_APIC() in
211  * one form or other. kexec jump path also need
212  * one.
213  */
214  disable_IO_APIC();
215 #endif
216  }
217 
218  control_page = page_address(image->control_code_page);
220 
221  relocate_kernel_ptr = control_page;
222  page_list[PA_CONTROL_PAGE] = __pa(control_page);
223  page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
224  page_list[PA_PGD] = __pa(image->arch.pgd);
225 
226  if (image->type == KEXEC_TYPE_DEFAULT)
227  page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
228  << PAGE_SHIFT);
229 
230  /*
231  * The segment registers are funny things, they have both a
232  * visible and an invisible part. Whenever the visible part is
233  * set to a specific selector, the invisible part is loaded
234  * with from a table in memory. At no other time is the
235  * descriptor table in memory accessed.
236  *
237  * I take advantage of this here by force loading the
238  * segments, before I zap the gdt with an invalid value.
239  */
240  load_segments();
241  /*
242  * The gdt & idt are now invalid.
243  * If you want to load them you must set up your own idt & gdt.
244  */
245  set_gdt(phys_to_virt(0), 0);
246  set_idt(phys_to_virt(0), 0);
247 
248  /* now call it */
249  image->start = relocate_kernel_ptr((unsigned long)image->head,
250  (unsigned long)page_list,
251  image->start, cpu_has_pae,
252  image->preserve_context);
253 
254 #ifdef CONFIG_KEXEC_JUMP
255  if (image->preserve_context)
257 #endif
258 
259  __ftrace_enabled_restore(save_ftrace_enabled);
260 }
261 
263 {
264 #ifdef CONFIG_NUMA
265  VMCOREINFO_SYMBOL(node_data);
266  VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
267 #endif
268 #ifdef CONFIG_X86_PAE
269  VMCOREINFO_CONFIG(X86_PAE);
270 #endif
271 }
272