/* SPDX-License-Identifier: GPL-2.0
 *
 * relocate_kernel.S - put the kernel image in place to boot
 * 2005.9.17 kogiidena@eggplant.ddo.jp
 *
 * LANDISK/sh4 is supported. Maybe, SH archtecture works well.
 *
 * 2009-03-18 Magnus Damm - Added Kexec Jump support
 */
#include <linux/linkage.h>
#include <asm/addrspace.h>
#include <asm/page.h>

                .globl relocate_new_kernel
relocate_new_kernel:
        /* r4 = indirection_page   */
        /* r5 = reboot_code_buffer */
        /* r6 = start_address      */

        mov.l   10f, r0         /* PAGE_SIZE */
        add     r5, r0          /* setup new stack at end of control page */

        /* save r15->r8 to new stack */
        mov.l   r15, @-r0
        mov     r0, r15
        mov.l   r14, @-r15
        mov.l   r13, @-r15
        mov.l   r12, @-r15
        mov.l   r11, @-r15
        mov.l   r10, @-r15
        mov.l   r9, @-r15
        mov.l   r8, @-r15

        /* save other random registers */
        sts.l   macl, @-r15
        sts.l   mach, @-r15
        stc.l   gbr, @-r15
        stc.l   ssr, @-r15
        stc.l   sr, @-r15
        sts.l   pr, @-r15
        stc.l   spc, @-r15

        /* switch to bank1 and save r7->r0 */
        mov.l   12f, r9
        stc     sr, r8
        or      r9, r8
        ldc     r8, sr
        mov.l   r7, @-r15
        mov.l   r6, @-r15
        mov.l   r5, @-r15
        mov.l   r4, @-r15
        mov.l   r3, @-r15
        mov.l   r2, @-r15
        mov.l   r1, @-r15
        mov.l   r0, @-r15

        /* switch to bank0 and save r7->r0 */
        mov.l   12f, r9
        not     r9, r9
        stc     sr, r8
        and     r9, r8
        ldc     r8, sr
        mov.l   r7, @-r15
        mov.l   r6, @-r15
        mov.l   r5, @-r15
        mov.l   r4, @-r15
        mov.l   r3, @-r15
        mov.l   r2, @-r15
        mov.l   r1, @-r15
        mov.l   r0, @-r15

        mov.l   r4, @-r15       /* save indirection page again */

        bsr     swap_pages      /* swap pages before jumping to new kernel */
         nop

        mova    11f, r0
        mov.l   r15, @r0        /* save pointer to stack */

        jsr     @r6             /* hand over control to new kernel */
         nop

        mov.l   11f, r15        /* get pointer to stack */
        mov.l   @r15+, r4       /* restore r4 to get indirection page */

        bsr     swap_pages      /* swap pages back to previous state */
         nop

        /* make sure bank0 is active and restore r0->r7 */
        mov.l   12f, r9
        not     r9, r9
        stc     sr, r8
        and     r9, r8
        ldc     r8, sr
        mov.l   @r15+, r0
        mov.l   @r15+, r1
        mov.l   @r15+, r2
        mov.l   @r15+, r3
        mov.l   @r15+, r4
        mov.l   @r15+, r5
        mov.l   @r15+, r6
        mov.l   @r15+, r7

        /* switch to bank1 and restore r0->r7 */
        mov.l   12f, r9
        stc     sr, r8
        or      r9, r8
        ldc     r8, sr
        mov.l   @r15+, r0
        mov.l   @r15+, r1
        mov.l   @r15+, r2
        mov.l   @r15+, r3
        mov.l   @r15+, r4
        mov.l   @r15+, r5
        mov.l   @r15+, r6
        mov.l   @r15+, r7

        /* switch back to bank0 */
        mov.l   12f, r9
        not     r9, r9
        stc     sr, r8
        and     r9, r8
        ldc     r8, sr

        /* restore other random registers */
        ldc.l   @r15+, spc
        lds.l   @r15+, pr
        ldc.l   @r15+, sr
        ldc.l   @r15+, ssr
        ldc.l   @r15+, gbr
        lds.l   @r15+, mach
        lds.l   @r15+, macl

        /* restore r8->r15 */
        mov.l   @r15+, r8
        mov.l   @r15+, r9
        mov.l   @r15+, r10
        mov.l   @r15+, r11
        mov.l   @r15+, r12
        mov.l   @r15+, r13
        mov.l   @r15+, r14
        mov.l   @r15+, r15
        rts
         nop

swap_pages:
        bra     1f
         mov    r4,r0     /* cmd = indirection_page */
0:
        mov.l   @r4+,r0   /* cmd = *ind++ */

1:      /* addr = cmd & 0xfffffff0 */
        mov     r0,r2
        mov     #-16,r1
        and     r1,r2

        /* if(cmd & IND_DESTINATION) dst = addr  */
        tst     #1,r0
        bt      2f
        bra     0b
         mov    r2,r5

2:      /* else if(cmd & IND_INDIRECTION) ind = addr  */
        tst     #2,r0
        bt      3f
        bra     0b
         mov    r2,r4

3:      /* else if(cmd & IND_DONE) return */
        tst     #4,r0
        bt      4f
        rts
         nop

4:      /* else if(cmd & IND_SOURCE) memcpy(dst,addr,PAGE_SIZE) */
        tst     #8,r0
        bt      0b

        mov.l   10f,r3    /* PAGE_SIZE */
        shlr2   r3
        shlr2   r3
5:
        dt      r3

        /* regular kexec just overwrites the destination page
         * with the contents of the source page.
         * for the kexec jump case we need to swap the contents
         * of the pages.
         * to keep it simple swap the contents for both cases.
         */
        mov.l   @(0, r2), r8
        mov.l   @(0, r5), r1
        mov.l   r8, @(0, r5)
        mov.l   r1, @(0, r2)

        mov.l   @(4, r2), r8
        mov.l   @(4, r5), r1
        mov.l   r8, @(4, r5)
        mov.l   r1, @(4, r2)

        mov.l   @(8, r2), r8
        mov.l   @(8, r5), r1
        mov.l   r8, @(8, r5)
        mov.l   r1, @(8, r2)

        mov.l   @(12, r2), r8
        mov.l   @(12, r5), r1
        mov.l   r8, @(12, r5)
        mov.l   r1, @(12, r2)

        add     #16,r5
        add     #16,r2
        bf      5b

        bra     0b
         nop

        .align 2
10:
        .long   PAGE_SIZE
11:
        .long   0
12:
        .long   0x20000000 ! RB=1

relocate_new_kernel_end:

        .globl relocate_new_kernel_size
relocate_new_kernel_size:
        .long relocate_new_kernel_end - relocate_new_kernel