LXR linux/arch/powerpc/purgatory/trampoline.S

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * kexec trampoline
   4 *
   5 * Based on code taken from kexec-tools and kexec-lite.
   6 *
   7 * Copyright (C) 2004 - 2005, Milton D Miller II, IBM Corporation
   8 * Copyright (C) 2006, Mohan Kumar M, IBM Corporation
   9 * Copyright (C) 2013, Anton Blanchard, IBM Corporation
  10 */
  11
  12#include <asm/asm-compat.h>
  13
  14        .machine ppc64
  15        .balign 256
  16        .globl purgatory_start
  17purgatory_start:
  18        b       master
  19
  20        /* ABI: possible run_at_load flag at 0x5c */
  21        .org purgatory_start + 0x5c
  22        .globl run_at_load
  23run_at_load:
  24        .long 0
  25        .size run_at_load, . - run_at_load
  26
  27        /* ABI: slaves start at 60 with r3=phys */
  28        .org purgatory_start + 0x60
  29slave:
  30        b .
  31        /* ABI: end of copied region */
  32        .org purgatory_start + 0x100
  33        .size purgatory_start, . - purgatory_start
  34
  35/*
  36 * The above 0x100 bytes at purgatory_start are replaced with the
  37 * code from the kernel (or next stage) by setup_purgatory().
  38 */
  39
  40master:
  41        or      %r1,%r1,%r1     /* low priority to let other threads catchup */
  42        isync
  43        mr      %r17,%r3        /* save cpu id to r17 */
  44        mr      %r15,%r4        /* save physical address in reg15 */
  45
  46        or      %r3,%r3,%r3     /* ok now to high priority, lets boot */
  47        lis     %r6,0x1
  48        mtctr   %r6             /* delay a bit for slaves to catch up */
  49        bdnz    .               /* before we overwrite 0-100 again */
  50
  51        bl      0f              /* Work out where we're running */
  520:      mflr    %r18
  53
  54        /* load device-tree address */
  55        ld      %r3, (dt_offset - 0b)(%r18)
  56        mr      %r16,%r3        /* save dt address in reg16 */
  57        li      %r4,20
  58        LWZX_BE %r6,%r3,%r4     /* fetch __be32 version number at byte 20 */
  59        cmpwi   %cr0,%r6,2      /* v2 or later? */
  60        blt     1f
  61        li      %r4,28
  62        STWX_BE %r17,%r3,%r4    /* Store my cpu as __be32 at byte 28 */
  631:
  64        /* load the kernel address */
  65        ld      %r4,(kernel - 0b)(%r18)
  66
  67        /* load the run_at_load flag */
  68        /* possibly patched by kexec */
  69        ld      %r6,(run_at_load - 0b)(%r18)
  70        /* and patch it into the kernel */
  71        stw     %r6,(0x5c)(%r4)
  72
  73        mr      %r3,%r16        /* restore dt address */
  74
  75        li      %r5,0           /* r5 will be 0 for kernel */
  76
  77        mfmsr   %r11
  78        andi.   %r10,%r11,1     /* test MSR_LE */
  79        bne     .Little_endian
  80
  81        mtctr   %r4             /* prepare branch to */
  82        bctr                    /* start kernel */
  83
  84.Little_endian:
  85        mtsrr0  %r4             /* prepare branch to */
  86
  87        clrrdi  %r11,%r11,1     /* clear MSR_LE */
  88        mtsrr1  %r11
  89
  90        rfid                    /* update MSR and start kernel */
  91
  92
  93        .balign 8
  94        .globl kernel
  95kernel:
  96        .8byte  0x0
  97        .size kernel, . - kernel
  98
  99        .balign 8
 100        .globl dt_offset
 101dt_offset:
 102        .8byte  0x0
 103        .size dt_offset, . - dt_offset
 104
 105
 106        .data
 107        .balign 8
 108.globl purgatory_sha256_digest
 109purgatory_sha256_digest:
 110        .skip   32
 111        .size purgatory_sha256_digest, . - purgatory_sha256_digest
 112
 113        .balign 8
 114.globl purgatory_sha_regions
 115purgatory_sha_regions:
 116        .skip   8 * 2 * 16
 117        .size purgatory_sha_regions, . - purgatory_sha_regions
 118