1/* SPDX-License-Identifier: GPL-2.0
2 *
3 * relocate_kernel.S - put the kernel image in place to boot
4 * 2005.9.17 kogiidena@eggplant.ddo.jp
5 *
6 * LANDISK/sh4 is supported. Maybe, SH archtecture works well.
7 *
8 * 2009-03-18 Magnus Damm - Added Kexec Jump support
9 */
10#include <linux/linkage.h>
11#include <asm/addrspace.h>
12#include <asm/page.h>
13
14 .globl relocate_new_kernel
15relocate_new_kernel:
16 /* r4 = indirection_page */
17 /* r5 = reboot_code_buffer */
18 /* r6 = start_address */
19
20 mov.l 10f, r0 /* PAGE_SIZE */
21 add r5, r0 /* setup new stack at end of control page */
22
23 /* save r15->r8 to new stack */
24 mov.l r15, @-r0
25 mov r0, r15
26 mov.l r14, @-r15
27 mov.l r13, @-r15
28 mov.l r12, @-r15
29 mov.l r11, @-r15
30 mov.l r10, @-r15
31 mov.l r9, @-r15
32 mov.l r8, @-r15
33
34 /* save other random registers */
35 sts.l macl, @-r15
36 sts.l mach, @-r15
37 stc.l gbr, @-r15
38 stc.l ssr, @-r15
39 stc.l sr, @-r15
40 sts.l pr, @-r15
41 stc.l spc, @-r15
42
43 /* switch to bank1 and save r7->r0 */
44 mov.l 12f, r9
45 stc sr, r8
46 or r9, r8
47 ldc r8, sr
48 mov.l r7, @-r15
49 mov.l r6, @-r15
50 mov.l r5, @-r15
51 mov.l r4, @-r15
52 mov.l r3, @-r15
53 mov.l r2, @-r15
54 mov.l r1, @-r15
55 mov.l r0, @-r15
56
57 /* switch to bank0 and save r7->r0 */
58 mov.l 12f, r9
59 not r9, r9
60 stc sr, r8
61 and r9, r8
62 ldc r8, sr
63 mov.l r7, @-r15
64 mov.l r6, @-r15
65 mov.l r5, @-r15
66 mov.l r4, @-r15
67 mov.l r3, @-r15
68 mov.l r2, @-r15
69 mov.l r1, @-r15
70 mov.l r0, @-r15
71
72 mov.l r4, @-r15 /* save indirection page again */
73
74 bsr swap_pages /* swap pages before jumping to new kernel */
75 nop
76
77 mova 11f, r0
78 mov.l r15, @r0 /* save pointer to stack */
79
80 jsr @r6 /* hand over control to new kernel */
81 nop
82
83 mov.l 11f, r15 /* get pointer to stack */
84 mov.l @r15+, r4 /* restore r4 to get indirection page */
85
86 bsr swap_pages /* swap pages back to previous state */
87 nop
88
89 /* make sure bank0 is active and restore r0->r7 */
90 mov.l 12f, r9
91 not r9, r9
92 stc sr, r8
93 and r9, r8
94 ldc r8, sr
95 mov.l @r15+, r0
96 mov.l @r15+, r1
97 mov.l @r15+, r2
98 mov.l @r15+, r3
99 mov.l @r15+, r4
100 mov.l @r15+, r5
101 mov.l @r15+, r6
102 mov.l @r15+, r7
103
104 /* switch to bank1 and restore r0->r7 */
105 mov.l 12f, r9
106 stc sr, r8
107 or r9, r8
108 ldc r8, sr
109 mov.l @r15+, r0
110 mov.l @r15+, r1
111 mov.l @r15+, r2
112 mov.l @r15+, r3
113 mov.l @r15+, r4
114 mov.l @r15+, r5
115 mov.l @r15+, r6
116 mov.l @r15+, r7
117
118 /* switch back to bank0 */
119 mov.l 12f, r9
120 not r9, r9
121 stc sr, r8
122 and r9, r8
123 ldc r8, sr
124
125 /* restore other random registers */
126 ldc.l @r15+, spc
127 lds.l @r15+, pr
128 ldc.l @r15+, sr
129 ldc.l @r15+, ssr
130 ldc.l @r15+, gbr
131 lds.l @r15+, mach
132 lds.l @r15+, macl
133
134 /* restore r8->r15 */
135 mov.l @r15+, r8
136 mov.l @r15+, r9
137 mov.l @r15+, r10
138 mov.l @r15+, r11
139 mov.l @r15+, r12
140 mov.l @r15+, r13
141 mov.l @r15+, r14
142 mov.l @r15+, r15
143 rts
144 nop
145
146swap_pages:
147 bra 1f
148 mov r4,r0 /* cmd = indirection_page */
1490:
150 mov.l @r4+,r0 /* cmd = *ind++ */
151
1521: /* addr = cmd & 0xfffffff0 */
153 mov r0,r2
154 mov #-16,r1
155 and r1,r2
156
157 /* if(cmd & IND_DESTINATION) dst = addr */
158 tst #1,r0
159 bt 2f
160 bra 0b
161 mov r2,r5
162
1632: /* else if(cmd & IND_INDIRECTION) ind = addr */
164 tst #2,r0
165 bt 3f
166 bra 0b
167 mov r2,r4
168
1693: /* else if(cmd & IND_DONE) return */
170 tst #4,r0
171 bt 4f
172 rts
173 nop
174
1754: /* else if(cmd & IND_SOURCE) memcpy(dst,addr,PAGE_SIZE) */
176 tst #8,r0
177 bt 0b
178
179 mov.l 10f,r3 /* PAGE_SIZE */
180 shlr2 r3
181 shlr2 r3
1825:
183 dt r3
184
185 /* regular kexec just overwrites the destination page
186 * with the contents of the source page.
187 * for the kexec jump case we need to swap the contents
188 * of the pages.
189 * to keep it simple swap the contents for both cases.
190 */
191 mov.l @(0, r2), r8
192 mov.l @(0, r5), r1
193 mov.l r8, @(0, r5)
194 mov.l r1, @(0, r2)
195
196 mov.l @(4, r2), r8
197 mov.l @(4, r5), r1
198 mov.l r8, @(4, r5)
199 mov.l r1, @(4, r2)
200
201 mov.l @(8, r2), r8
202 mov.l @(8, r5), r1
203 mov.l r8, @(8, r5)
204 mov.l r1, @(8, r2)
205
206 mov.l @(12, r2), r8
207 mov.l @(12, r5), r1
208 mov.l r8, @(12, r5)
209 mov.l r1, @(12, r2)
210
211 add #16,r5
212 add #16,r2
213 bf 5b
214
215 bra 0b
216 nop
217
218 .align 2
21910:
220 .long PAGE_SIZE
22111:
222 .long 0
22312:
224 .long 0x20000000 ! RB=1
225
226relocate_new_kernel_end:
227
228 .globl relocate_new_kernel_size
229relocate_new_kernel_size:
230 .long relocate_new_kernel_end - relocate_new_kernel
231

source code of linux/arch/sh/kernel/relocate_kernel.S