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     x18, x2                         /* x18 = dtb address */
  36         mov     x17, x1                         /* x17 = kimage_start */
  37         mov     x16, x0                         /* x16 = kimage_head */
  38         raw_dcache_line_size x15, x0            /* x15 = dcache line size */
  39         mov     x14, xzr                        /* x14 = entry ptr */
  40         mov     x13, xzr                        /* x13 = copy dest */
  41
  42         /* Clear the sctlr_el2 flags. */
  43         mrs     x0, CurrentEL
  44         cmp     x0, #CurrentEL_EL2
  45         b.ne    1f
  46         mrs     x0, sctlr_el2
  47         ldr     x1, =SCTLR_ELx_FLAGS
  48         bic     x0, x0, x1
  49         pre_disable_mmu_workaround
  50         msr     sctlr_el2, x0
  51         isb
  52 1:
  53
  54         /* Check if the new image needs relocation. */
  55         tbnz    x16, IND_DONE_BIT, .Ldone
  56
  57 .Lloop:
  58         and     x12, x16, PAGE_MASK             /* x12 = addr */
  59
  60         /* Test the entry flags. */
  61 .Ltest_source:
  62         tbz     x16, IND_SOURCE_BIT, .Ltest_indirection
  63
  64         /* Invalidate dest page to PoC. */
  65         mov     x0, x13
  66         add     x20, x0, #PAGE_SIZE
  67         sub     x1, x15, #1
  68         bic     x0, x0, x1
  69 2:      dc      ivac, x0
  70         add     x0, x0, x15
  71         cmp     x0, x20
  72         b.lo    2b
  73         dsb     sy
  74
  75         mov x20, x13
  76         mov x21, x12
  77         copy_page x20, x21, x0, x1, x2, x3, x4, x5, x6, x7
  78
  79         /* dest += PAGE_SIZE */
  80         add     x13, x13, PAGE_SIZE
  81         b       .Lnext
  82
  83 .Ltest_indirection:
  84         tbz     x16, IND_INDIRECTION_BIT, .Ltest_destination
  85
  86         /* ptr = addr */
  87         mov     x14, x12
  88         b       .Lnext
  89
  90 .Ltest_destination:
  91         tbz     x16, IND_DESTINATION_BIT, .Lnext
  92
  93         /* dest = addr */
  94         mov     x13, x12
  95
  96 .Lnext:
  97         /* entry = *ptr++ */
  98         ldr     x16, [x14], #8
  99
 100         /* while (!(entry & DONE)) */
 101         tbz     x16, IND_DONE_BIT, .Lloop
 102
 103 .Ldone:
 104         /* wait for writes from copy_page to finish */
 105         dsb     nsh
 106         ic      iallu
 107         dsb     nsh
 108         isb
 109
 110         /* Start new image. */
 111         mov     x0, x18
 112         mov     x1, xzr
 113         mov     x2, xzr
 114         mov     x3, xzr
 115         br      x17
 116
 117 ENDPROC(arm64_relocate_new_kernel)
 118
 119 .ltorg
 120
 121 .align 3        /* To keep the 64-bit values below naturally aligned. */
 122
 123 .Lcopy_end:
 124 .org    KEXEC_CONTROL_PAGE_SIZE
 125
 126 /*
 127  * arm64_relocate_new_kernel_size - Number of bytes to copy to the
 128  * control_code_page.
 129  */
 130 .globl arm64_relocate_new_kernel_size
 131 arm64_relocate_new_kernel_size:
 132         .quad   .Lcopy_end - arm64_relocate_new_kernel