LXR linux/arch/powerpc/purgatory/trampoline

   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#include <asm/crashdump-ppc64.h>
  14
  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        /* Work out where we're running */
  47        bcl     20, 31, 0f
  480:      mflr    %r18
  49
  50        /*
  51         * Copy BACKUP_SRC_SIZE bytes from BACKUP_SRC_START to
  52         * backup_start 8 bytes at a time.
  53         *
  54         * Use r3 = dest, r4 = src, r5 = size, r6 = count
  55         */
  56        ld      %r3, (backup_start - 0b)(%r18)
  57        cmpdi   %cr0, %r3, 0
  58        beq     .Lskip_copy     /* skip if there is no backup region */
  59        lis     %r5, BACKUP_SRC_SIZE@h
  60        ori     %r5, %r5, BACKUP_SRC_SIZE@l
  61        cmpdi   %cr0, %r5, 0
  62        beq     .Lskip_copy     /* skip if copy size is zero */
  63        lis     %r4, BACKUP_SRC_START@h
  64        ori     %r4, %r4, BACKUP_SRC_START@l
  65        li      %r6, 0
  66.Lcopy_loop:
  67        ldx     %r0, %r6, %r4
  68        stdx    %r0, %r6, %r3
  69        addi    %r6, %r6, 8
  70        cmpld   %cr0, %r6, %r5
  71        blt     .Lcopy_loop
  72
  73.Lskip_copy:
  74        or      %r3,%r3,%r3     /* ok now to high priority, lets boot */
  75        lis     %r6,0x1
  76        mtctr   %r6             /* delay a bit for slaves to catch up */
  77        bdnz    .               /* before we overwrite 0-100 again */
  78
  79        /* load device-tree address */
  80        ld      %r3, (dt_offset - 0b)(%r18)
  81        mr      %r16,%r3        /* save dt address in reg16 */
  82        li      %r4,20
  83        LWZX_BE %r6,%r3,%r4     /* fetch __be32 version number at byte 20 */
  84        cmpwi   %cr0,%r6,2      /* v2 or later? */
  85        blt     1f
  86        li      %r4,28
  87        STWX_BE %r17,%r3,%r4    /* Store my cpu as __be32 at byte 28 */
  881:
  89        /* Load opal base and entry values in r8 & r9 respectively */
  90        ld      %r8,(opal_base - 0b)(%r18)
  91        ld      %r9,(opal_entry - 0b)(%r18)
  92
  93        /* load the kernel address */
  94        ld      %r4,(kernel - 0b)(%r18)
  95
  96        /* load the run_at_load flag */
  97        /* possibly patched by kexec */
  98        ld      %r6,(run_at_load - 0b)(%r18)
  99        /* and patch it into the kernel */
 100        stw     %r6,(0x5c)(%r4)
 101
 102        mr      %r3,%r16        /* restore dt address */
 103
 104        li      %r5,0           /* r5 will be 0 for kernel */
 105
 106        mfmsr   %r11
 107        andi.   %r10,%r11,1     /* test MSR_LE */
 108        bne     .Little_endian
 109
 110        mtctr   %r4             /* prepare branch to */
 111        bctr                    /* start kernel */
 112
 113.Little_endian:
 114        mtsrr0  %r4             /* prepare branch to */
 115
 116        clrrdi  %r11,%r11,1     /* clear MSR_LE */
 117        mtsrr1  %r11
 118
 119        rfid                    /* update MSR and start kernel */
 120
 121        .balign 8
 122        .globl kernel
 123kernel:
 124        .8byte  0x0
 125        .size kernel, . - kernel
 126
 127        .balign 8
 128        .globl dt_offset
 129dt_offset:
 130        .8byte  0x0
 131        .size dt_offset, . - dt_offset
 132
 133        .balign 8
 134        .globl backup_start
 135backup_start:
 136        .8byte  0x0
 137        .size backup_start, . - backup_start
 138
 139        .balign 8
 140        .globl opal_base
 141opal_base:
 142        .8byte  0x0
 143        .size opal_base, . - opal_base
 144
 145        .balign 8
 146        .globl opal_entry
 147opal_entry:
 148        .8byte  0x0
 149        .size opal_entry, . - opal_entry
 150
 151        .data
 152        .balign 8
 153.globl purgatory_sha256_digest
 154purgatory_sha256_digest:
 155        .skip   32
 156        .size purgatory_sha256_digest, . - purgatory_sha256_digest
 157
 158        .balign 8
 159.globl purgatory_sha_regions
 160purgatory_sha_regions:
 161        .skip   8 * 2 * 16
 162        .size purgatory_sha_regions, . - purgatory_sha_regions
 163