arch/x86/kernel/relocate_kernel_64.S

   1 /*
   2  * relocate_kernel.S - put the kernel image in place to boot
   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/linkage.h>
  10 #include <asm/page_types.h>
  11 #include <asm/kexec.h>
  12 #include <asm/processor-flags.h>
  13 #include <asm/pgtable_types.h>
  14
  15 /*
  16  * Must be relocatable PIC code callable as a C function
  17  */
  18
  19 #define PTR(x) (x << 3)
  20 #define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
  21
  22 /*
  23  * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
  24  * ~ control_page + PAGE_SIZE are used as data storage and stack for
  25  * jumping back
  26  */
  27 #define DATA(offset)            (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
  28
  29 /* Minimal CPU state */
  30 #define RSP                     DATA(0x0)
  31 #define CR0                     DATA(0x8)
  32 #define CR3                     DATA(0x10)
  33 #define CR4                     DATA(0x18)
  34
  35 /* other data */
  36 #define CP_PA_TABLE_PAGE        DATA(0x20)
  37 #define CP_PA_SWAP_PAGE         DATA(0x28)
  38 #define CP_PA_BACKUP_PAGES_MAP  DATA(0x30)
  39
  40         .text
  41         .align PAGE_SIZE
  42         .code64
  43         .globl relocate_kernel
  44 relocate_kernel:
  45         /*
  46          * %rdi indirection_page
  47          * %rsi page_list
  48          * %rdx start address
  49          * %rcx preserve_context
  50          * %r8  sme_active
  51          */
  52
  53         /* Save the CPU context, used for jumping back */
  54         pushq %rbx
  55         pushq %rbp
  56         pushq %r12
  57         pushq %r13
  58         pushq %r14
  59         pushq %r15
  60         pushf
  61
  62         movq    PTR(VA_CONTROL_PAGE)(%rsi), %r11
  63         movq    %rsp, RSP(%r11)
  64         movq    %cr0, %rax
  65         movq    %rax, CR0(%r11)
  66         movq    %cr3, %rax
  67         movq    %rax, CR3(%r11)
  68         movq    %cr4, %rax
  69         movq    %rax, CR4(%r11)
  70
  71         /* Save CR4. Required to enable the right paging mode later. */
  72         movq    %rax, %r13
  73
  74         /* zero out flags, and disable interrupts */
  75         pushq $0
  76         popfq
  77
  78         /* Save SME active flag */
  79         movq    %r8, %r12
  80
  81         /*
  82          * get physical address of control page now
  83          * this is impossible after page table switch
  84          */
  85         movq    PTR(PA_CONTROL_PAGE)(%rsi), %r8
  86
  87         /* get physical address of page table now too */
  88         movq    PTR(PA_TABLE_PAGE)(%rsi), %r9
  89
  90         /* get physical address of swap page now */
  91         movq    PTR(PA_SWAP_PAGE)(%rsi), %r10
  92
  93         /* save some information for jumping back */
  94         movq    %r9, CP_PA_TABLE_PAGE(%r11)
  95         movq    %r10, CP_PA_SWAP_PAGE(%r11)
  96         movq    %rdi, CP_PA_BACKUP_PAGES_MAP(%r11)
  97
  98         /* Switch to the identity mapped page tables */
  99         movq    %r9, %cr3
 100
 101         /* setup a new stack at the end of the physical control page */
 102         lea     PAGE_SIZE(%r8), %rsp
 103
 104         /* jump to identity mapped page */
 105         addq    $(identity_mapped - relocate_kernel), %r8
 106         pushq   %r8
 107         ret
 108
 109 identity_mapped:
 110         /* set return address to 0 if not preserving context */
 111         pushq   $0
 112         /* store the start address on the stack */
 113         pushq   %rdx
 114
 115         /*
 116          * Set cr0 to a known state:
 117          *  - Paging enabled
 118          *  - Alignment check disabled
 119          *  - Write protect disabled
 120          *  - No task switch
 121          *  - Don't do FP software emulation.
 122          *  - Proctected mode enabled
 123          */
 124         movq    %cr0, %rax
 125         andq    $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
 126         orl     $(X86_CR0_PG | X86_CR0_PE), %eax
 127         movq    %rax, %cr0
 128
 129         /*
 130          * Set cr4 to a known state:
 131          *  - physical address extension enabled
 132          *  - 5-level paging, if it was enabled before
 133          */
 134         movl    $X86_CR4_PAE, %eax
 135         testq   $X86_CR4_LA57, %r13
 136         jz      1f
 137         orl     $X86_CR4_LA57, %eax
 138 1:
 139         movq    %rax, %cr4
 140
 141         jmp 1f
 142 1:
 143
 144         /* Flush the TLB (needed?) */
 145         movq    %r9, %cr3
 146
 147         /*
 148          * If SME is active, there could be old encrypted cache line
 149          * entries that will conflict with the now unencrypted memory
 150          * used by kexec. Flush the caches before copying the kernel.
 151          */
 152         testq   %r12, %r12
 153         jz 1f
 154         wbinvd
 155 1:
 156
 157         movq    %rcx, %r11
 158         call    swap_pages
 159
 160         /*
 161          * To be certain of avoiding problems with self-modifying code
 162          * I need to execute a serializing instruction here.
 163          * So I flush the TLB by reloading %cr3 here, it's handy,
 164          * and not processor dependent.
 165          */
 166         movq    %cr3, %rax
 167         movq    %rax, %cr3
 168
 169         /*
 170          * set all of the registers to known values
 171          * leave %rsp alone
 172          */
 173
 174         testq   %r11, %r11
 175         jnz 1f
 176         xorl    %eax, %eax
 177         xorl    %ebx, %ebx
 178         xorl    %ecx, %ecx
 179         xorl    %edx, %edx
 180         xorl    %esi, %esi
 181         xorl    %edi, %edi
 182         xorl    %ebp, %ebp
 183         xorl    %r8d, %r8d
 184         xorl    %r9d, %r9d
 185         xorl    %r10d, %r10d
 186         xorl    %r11d, %r11d
 187         xorl    %r12d, %r12d
 188         xorl    %r13d, %r13d
 189         xorl    %r14d, %r14d
 190         xorl    %r15d, %r15d
 191
 192         ret
 193
 194 1:
 195         popq    %rdx
 196         leaq    PAGE_SIZE(%r10), %rsp
 197         call    *%rdx
 198
 199         /* get the re-entry point of the peer system */
 200         movq    0(%rsp), %rbp
 201         call    1f
 202 1:
 203         popq    %r8
 204         subq    $(1b - relocate_kernel), %r8
 205         movq    CP_PA_SWAP_PAGE(%r8), %r10
 206         movq    CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
 207         movq    CP_PA_TABLE_PAGE(%r8), %rax
 208         movq    %rax, %cr3
 209         lea     PAGE_SIZE(%r8), %rsp
 210         call    swap_pages
 211         movq    $virtual_mapped, %rax
 212         pushq   %rax
 213         ret
 214
 215 virtual_mapped:
 216         movq    RSP(%r8), %rsp
 217         movq    CR4(%r8), %rax
 218         movq    %rax, %cr4
 219         movq    CR3(%r8), %rax
 220         movq    CR0(%r8), %r8
 221         movq    %rax, %cr3
 222         movq    %r8, %cr0
 223         movq    %rbp, %rax
 224
 225         popf
 226         popq    %r15
 227         popq    %r14
 228         popq    %r13
 229         popq    %r12
 230         popq    %rbp
 231         popq    %rbx
 232         ret
 233
 234         /* Do the copies */
 235 swap_pages:
 236         movq    %rdi, %rcx      /* Put the page_list in %rcx */
 237         xorl    %edi, %edi
 238         xorl    %esi, %esi
 239         jmp     1f
 240
 241 0:      /* top, read another word for the indirection page */
 242
 243         movq    (%rbx), %rcx
 244         addq    $8,     %rbx
 245 1:
 246         testb   $0x1,   %cl   /* is it a destination page? */
 247         jz      2f
 248         movq    %rcx,   %rdi
 249         andq    $0xfffffffffffff000, %rdi
 250         jmp     0b
 251 2:
 252         testb   $0x2,   %cl   /* is it an indirection page? */
 253         jz      2f
 254         movq    %rcx,   %rbx
 255         andq    $0xfffffffffffff000, %rbx
 256         jmp     0b
 257 2:
 258         testb   $0x4,   %cl   /* is it the done indicator? */
 259         jz      2f
 260         jmp     3f
 261 2:
 262         testb   $0x8,   %cl   /* is it the source indicator? */
 263         jz      0b            /* Ignore it otherwise */
 264         movq    %rcx,   %rsi  /* For ever source page do a copy */
 265         andq    $0xfffffffffffff000, %rsi
 266
 267         movq    %rdi, %rdx
 268         movq    %rsi, %rax
 269
 270         movq    %r10, %rdi
 271         movl    $512, %ecx
 272         rep ; movsq
 273
 274         movq    %rax, %rdi
 275         movq    %rdx, %rsi
 276         movl    $512, %ecx
 277         rep ; movsq
 278
 279         movq    %rdx, %rdi
 280         movq    %r10, %rsi
 281         movl    $512, %ecx
 282         rep ; movsq
 283
 284         lea     PAGE_SIZE(%rax), %rsi
 285         jmp     0b
 286 3:
 287         ret
 288
 289         .globl kexec_control_code_size
 290 .set kexec_control_code_size, . - relocate_kernel