/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * kexec trampoline
 *
 * Based on code taken from kexec-tools and kexec-lite.
 *
 * Copyright (C) 2004 - 2005, Milton D Miller II, IBM Corporation
 * Copyright (C) 2006, Mohan Kumar M, IBM Corporation
 * Copyright (C) 2013, Anton Blanchard, IBM Corporation
 */

#include <asm/asm-compat.h>
#include <asm/crashdump-ppc64.h>

        .balign 256
        .globl purgatory_start
purgatory_start:
        b       master

        /* ABI: possible run_at_load flag at 0x5c */
        .org purgatory_start + 0x5c
        .globl run_at_load
run_at_load:
        .long 0
        .size run_at_load, . - run_at_load

        /* ABI: slaves start at 60 with r3=phys */
        .org purgatory_start + 0x60
slave:
        b .
        /* ABI: end of copied region */
        .org purgatory_start + 0x100
        .size purgatory_start, . - purgatory_start

/*
 * The above 0x100 bytes at purgatory_start are replaced with the
 * code from the kernel (or next stage) by setup_purgatory().
 */

master:
        or      %r1,%r1,%r1     /* low priority to let other threads catchup */
        isync
        mr      %r17,%r3        /* save cpu id to r17 */
        mr      %r15,%r4        /* save physical address in reg15 */

        /* Work out where we're running */
        bcl     20, 31, 0f
0:      mflr    %r18

        /*
         * Copy BACKUP_SRC_SIZE bytes from BACKUP_SRC_START to
         * backup_start 8 bytes at a time.
         *
         * Use r3 = dest, r4 = src, r5 = size, r6 = count
         */
        ld      %r3, (backup_start - 0b)(%r18)
        cmpdi   %cr0, %r3, 0
        beq     .Lskip_copy     /* skip if there is no backup region */
        lis     %r5, BACKUP_SRC_SIZE@h
        ori     %r5, %r5, BACKUP_SRC_SIZE@l
        cmpdi   %cr0, %r5, 0
        beq     .Lskip_copy     /* skip if copy size is zero */
        lis     %r4, BACKUP_SRC_START@h
        ori     %r4, %r4, BACKUP_SRC_START@l
        li      %r6, 0
.Lcopy_loop:
        ldx     %r0, %r6, %r4
        stdx    %r0, %r6, %r3
        addi    %r6, %r6, 8
        cmpld   %cr0, %r6, %r5
        blt     .Lcopy_loop

.Lskip_copy:
        or      %r3,%r3,%r3     /* ok now to high priority, lets boot */
        lis     %r6,0x1
        mtctr   %r6             /* delay a bit for slaves to catch up */
        bdnz    .               /* before we overwrite 0-100 again */

        /* load device-tree address */
        ld      %r3, (dt_offset - 0b)(%r18)
        mr      %r16,%r3        /* save dt address in reg16 */
        li      %r4,20
        LWZX_BE %r6,%r3,%r4     /* fetch __be32 version number at byte 20 */
        cmpwi   %cr0,%r6,2      /* v2 or later? */
        blt     1f
        li      %r4,28
        STWX_BE %r17,%r3,%r4    /* Store my cpu as __be32 at byte 28 */
1:
        /* Load opal base and entry values in r8 & r9 respectively */
        ld      %r8,(opal_base - 0b)(%r18)
        ld      %r9,(opal_entry - 0b)(%r18)

        /* load the kernel address */
        ld      %r4,(kernel - 0b)(%r18)

        /* load the run_at_load flag */
        /* possibly patched by kexec */
        ld      %r6,(run_at_load - 0b)(%r18)
        /* and patch it into the kernel */
        stw     %r6,(0x5c)(%r4)

        mr      %r3,%r16        /* restore dt address */

        li      %r5,0           /* r5 will be 0 for kernel */

        mfmsr   %r11
        andi.   %r10,%r11,1     /* test MSR_LE */
        bne     .Little_endian

        mtctr   %r4             /* prepare branch to */
        bctr                    /* start kernel */

.Little_endian:
        mtsrr0  %r4             /* prepare branch to */

        clrrdi  %r11,%r11,1     /* clear MSR_LE */
        mtsrr1  %r11

        rfid                    /* update MSR and start kernel */

        .balign 8
        .globl kernel
kernel:
        .8byte  0x0
        .size kernel, . - kernel

        .balign 8
        .globl dt_offset
dt_offset:
        .8byte  0x0
        .size dt_offset, . - dt_offset

        .balign 8
        .globl backup_start
backup_start:
        .8byte  0x0
        .size backup_start, . - backup_start

        .balign 8
        .globl opal_base
opal_base:
        .8byte  0x0
        .size opal_base, . - opal_base

        .balign 8
        .globl opal_entry
opal_entry:
        .8byte  0x0
        .size opal_entry, . - opal_entry

        .data
        .balign 8
.globl purgatory_sha256_digest
purgatory_sha256_digest:
        .skip   32
        .size purgatory_sha256_digest, . - purgatory_sha256_digest

        .balign 8
.globl purgatory_sha_regions
purgatory_sha_regions:
        .skip   8 * 2 * 16
        .size purgatory_sha_regions, . - purgatory_sha_regions