arch/powerpc/purgatory/trampoline.S

   1 /*
   2  * kexec trampoline
   3  *
   4  * Based on code taken from kexec-tools and kexec-lite.
   5  *
   6  * Copyright (C) 2004 - 2005, Milton D Miller II, IBM Corporation
   7  * Copyright (C) 2006, Mohan Kumar M, IBM Corporation
   8  * Copyright (C) 2013, Anton Blanchard, IBM Corporation
   9  *
  10  * This program is free software; you can redistribute it and/or modify it under
  11  * the terms of the GNU General Public License as published by the Free
  12  * Software Foundation (version 2 of the License).
  13  */
  14
  15 #if defined(__LITTLE_ENDIAN__)
  16 #define STWX_BE stwbrx
  17 #define LWZX_BE lwbrx
  18 #elif defined(__BIG_ENDIAN__)
  19 #define STWX_BE stwx
  20 #define LWZX_BE lwzx
  21 #else
  22 #error no endianness defined!
  23 #endif
  24
  25         .machine ppc64
  26         .balign 256
  27         .globl purgatory_start
  28 purgatory_start:
  29         b       master
  30
  31         /* ABI: possible run_at_load flag at 0x5c */
  32         .org purgatory_start + 0x5c
  33         .globl run_at_load
  34 run_at_load:
  35         .long 0
  36         .size run_at_load, . - run_at_load
  37
  38         /* ABI: slaves start at 60 with r3=phys */
  39         .org purgatory_start + 0x60
  40 slave:
  41         b .
  42         /* ABI: end of copied region */
  43         .org purgatory_start + 0x100
  44         .size purgatory_start, . - purgatory_start
  45
  46 /*
  47  * The above 0x100 bytes at purgatory_start are replaced with the
  48  * code from the kernel (or next stage) by setup_purgatory().
  49  */
  50
  51 master:
  52         or      %r1,%r1,%r1     /* low priority to let other threads catchup */
  53         isync
  54         mr      %r17,%r3        /* save cpu id to r17 */
  55         mr      %r15,%r4        /* save physical address in reg15 */
  56
  57         or      %r3,%r3,%r3     /* ok now to high priority, lets boot */
  58         lis     %r6,0x1
  59         mtctr   %r6             /* delay a bit for slaves to catch up */
  60         bdnz    .               /* before we overwrite 0-100 again */
  61
  62         bl      0f              /* Work out where we're running */
  63 0:      mflr    %r18
  64
  65         /* load device-tree address */
  66         ld      %r3, (dt_offset - 0b)(%r18)
  67         mr      %r16,%r3        /* save dt address in reg16 */
  68         li      %r4,20
  69         LWZX_BE %r6,%r3,%r4     /* fetch __be32 version number at byte 20 */
  70         cmpwi   %r0,%r6,2       /* v2 or later? */
  71         blt     1f
  72         li      %r4,28
  73         STWX_BE %r17,%r3,%r4    /* Store my cpu as __be32 at byte 28 */
  74 1:
  75         /* load the kernel address */
  76         ld      %r4,(kernel - 0b)(%r18)
  77
  78         /* load the run_at_load flag */
  79         /* possibly patched by kexec */
  80         ld      %r6,(run_at_load - 0b)(%r18)
  81         /* and patch it into the kernel */
  82         stw     %r6,(0x5c)(%r4)
  83
  84         mr      %r3,%r16        /* restore dt address */
  85
  86         li      %r5,0           /* r5 will be 0 for kernel */
  87
  88         mfmsr   %r11
  89         andi.   %r10,%r11,1     /* test MSR_LE */
  90         bne     .Little_endian
  91
  92         mtctr   %r4             /* prepare branch to */
  93         bctr                    /* start kernel */
  94
  95 .Little_endian:
  96         mtsrr0  %r4             /* prepare branch to */
  97
  98         clrrdi  %r11,%r11,1     /* clear MSR_LE */
  99         mtsrr1  %r11
 100
 101         rfid                    /* update MSR and start kernel */
 102
 103
 104         .balign 8
 105         .globl kernel
 106 kernel:
 107         .llong  0x0
 108         .size kernel, . - kernel
 109
 110         .balign 8
 111         .globl dt_offset
 112 dt_offset:
 113         .llong  0x0
 114         .size dt_offset, . - dt_offset
 115
 116
 117         .data
 118         .balign 8
 119 .globl sha256_digest
 120 sha256_digest:
 121         .skip   32
 122         .size sha256_digest, . - sha256_digest
 123
 124         .balign 8
 125 .globl sha_regions
 126 sha_regions:
 127         .skip   8 * 2 * 16
 128         .size sha_regions, . - sha_regions