arch/arm64/kernel/relocate_kernel.S

   1 /*
   2  * kexec for arm64
   3  *
   4  * Copyright (C) Linaro.
   5  * Copyright (C) Huawei Futurewei Technologies.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/kexec.h>
  13 #include <linux/linkage.h>
  14
  15 #include <asm/assembler.h>
  16 #include <asm/kexec.h>
  17 #include <asm/page.h>
  18 #include <asm/sysreg.h>
  19
  20 /*
  21  * arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it.
  22  *
  23  * The memory that the old kernel occupies may be overwritten when coping the
  24  * new image to its final location.  To assure that the
  25  * arm64_relocate_new_kernel routine which does that copy is not overwritten,
  26  * all code and data needed by arm64_relocate_new_kernel must be between the
  27  * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end.  The
  28  * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec
  29  * control_code_page, a special page which has been set up to be preserved
  30  * during the copy operation.
  31  */
  32 ENTRY(arm64_relocate_new_kernel)
  33
  34         /* Setup the list loop variables. */
  35         mov     x17, x1                         /* x17 = kimage_start */
  36         mov     x16, x0                         /* x16 = kimage_head */
  37         dcache_line_size x15, x0                /* x15 = dcache line size */
  38         mov     x14, xzr                        /* x14 = entry ptr */
  39         mov     x13, xzr                        /* x13 = copy dest */
  40
  41         /* Clear the sctlr_el2 flags. */
  42         mrs     x0, CurrentEL
  43         cmp     x0, #CurrentEL_EL2
  44         b.ne    1f
  45         mrs     x0, sctlr_el2
  46         ldr     x1, =SCTLR_ELx_FLAGS
  47         bic     x0, x0, x1
  48         msr     sctlr_el2, x0
  49         isb
  50 1:
  51
  52         /* Check if the new image needs relocation. */
  53         tbnz    x16, IND_DONE_BIT, .Ldone
  54
  55 .Lloop:
  56         and     x12, x16, PAGE_MASK             /* x12 = addr */
  57
  58         /* Test the entry flags. */
  59 .Ltest_source:
  60         tbz     x16, IND_SOURCE_BIT, .Ltest_indirection
  61
  62         /* Invalidate dest page to PoC. */
  63         mov     x0, x13
  64         add     x20, x0, #PAGE_SIZE
  65         sub     x1, x15, #1
  66         bic     x0, x0, x1
  67 2:      dc      ivac, x0
  68         add     x0, x0, x15
  69         cmp     x0, x20
  70         b.lo    2b
  71         dsb     sy
  72
  73         mov x20, x13
  74         mov x21, x12
  75         copy_page x20, x21, x0, x1, x2, x3, x4, x5, x6, x7
  76
  77         /* dest += PAGE_SIZE */
  78         add     x13, x13, PAGE_SIZE
  79         b       .Lnext
  80
  81 .Ltest_indirection:
  82         tbz     x16, IND_INDIRECTION_BIT, .Ltest_destination
  83
  84         /* ptr = addr */
  85         mov     x14, x12
  86         b       .Lnext
  87
  88 .Ltest_destination:
  89         tbz     x16, IND_DESTINATION_BIT, .Lnext
  90
  91         /* dest = addr */
  92         mov     x13, x12
  93
  94 .Lnext:
  95         /* entry = *ptr++ */
  96         ldr     x16, [x14], #8
  97
  98         /* while (!(entry & DONE)) */
  99         tbz     x16, IND_DONE_BIT, .Lloop
 100
 101 .Ldone:
 102         /* wait for writes from copy_page to finish */
 103         dsb     nsh
 104         ic      iallu
 105         dsb     nsh
 106         isb
 107
 108         /* Start new image. */
 109         mov     x0, xzr
 110         mov     x1, xzr
 111         mov     x2, xzr
 112         mov     x3, xzr
 113         br      x17
 114
 115 ENDPROC(arm64_relocate_new_kernel)
 116
 117 .ltorg
 118
 119 .align 3        /* To keep the 64-bit values below naturally aligned. */
 120
 121 .Lcopy_end:
 122 .org    KEXEC_CONTROL_PAGE_SIZE
 123
 124 /*
 125  * arm64_relocate_new_kernel_size - Number of bytes to copy to the
 126  * control_code_page.
 127  */
 128 .globl arm64_relocate_new_kernel_size
 129 arm64_relocate_new_kernel_size:
 130         .quad   .Lcopy_end - arm64_relocate_new_kernel