1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Purgatory setup code
4 *
5 * Copyright IBM Corp. 2018
6 *
7 * Author(s): Philipp Rudo <prudo@linux.vnet.ib
8 */
9
10 #include <linux/linkage.h>
11 #include <asm/asm-offsets.h>
12 #include <asm/page.h>
13 #include <asm/sigp.h>
14 #include <asm/ptrace.h>
15
16 /* The purgatory is the code running between t
17 * is to verify that the next kernel was not c
18 * start it.
19 *
20 * If the next kernel is a crash kernel there
21 * consider:
22 *
23 * First the purgatory is called twice. Once o
24 * sha digest. So if the crash kernel got corr
25 * to trigger a stand-alone dumper. And once t
26 *
27 * Second the purgatory also has to swap the c
28 * destination at address 0. As the purgatory
29 * requires some finesse. The tactic here is t
30 * itself to the end of the destination and th
31 * memory running from there.
32 */
33
34 #define bufsz purgatory_end-stack
35
36 .macro MEMCPY dst,src,len
37 lgr %r0,\dst
38 lgr %r1,\len
39 lgr %r2,\src
40 lgr %r3,\len
41
42 20: mvcle %r0,%r2,0
43 jo 20b
44 .endm
45
46 .macro MEMSWAP dst,src,buf,len
47 10: larl %r0,purgatory_end
48 larl %r1,stack
49 slgr %r0,%r1
50 cgr \len,%r0
51 jh 11f
52 lgr %r4,\len
53 j 12f
54 11: lgr %r4,%r0
55
56 12: MEMCPY \buf,\dst,%r4
57 MEMCPY \dst,\src,%r4
58 MEMCPY \src,\buf,%r4
59
60 agr \dst,%r4
61 agr \src,%r4
62 sgr \len,%r4
63
64 cghi \len,0
65 jh 10b
66 .endm
67
68 .macro START_NEXT_KERNEL base subcode
69 lg %r4,kernel_entry-\base(%r13)
70 lg %r5,load_psw_mask-\base(%r13)
71 ogr %r4,%r5
72 stg %r4,0(%r0)
73
74 xgr %r0,%r0
75 lghi %r1,\subcode
76 diag %r0,%r1,0x308
77 .endm
78
79 .text
80 .balign PAGE_SIZE
81 SYM_CODE_START(purgatory_start)
82 /* The purgatory might be called after
83 * architecture and addressing mode.
84 */
85 lhi %r1,1
86 sigp %r1,%r0,SIGP_SET_ARCHITECTURE
87 sam64
88
89 larl %r5,gprregs
90 stmg %r6,%r15,0(%r5)
91
92 basr %r13,0
93 .base_crash:
94
95 /* Setup stack */
96 larl %r15,purgatory_end-STACK_FRAME
97
98 /* If the next kernel is KEXEC_TYPE_CR
99 * directly with a flag passed in %r2
100 * checksum verification only (%r2 = 0
101 *
102 * Check now and preserve over C funct
103 * %r10 with
104 * 1 -> checksum verification onl
105 * 0 -> load new kernel
106 */
107 lghi %r10,0
108 lg %r11,kernel_type-.base_crash(%
109 cghi %r11,1 /* KEXEC_TYPE_
110 jne .do_checksum_verification
111 cghi %r2,0 /* checksum ve
112 jne .do_checksum_verification
113 lghi %r10,1
114
115 .do_checksum_verification:
116 brasl %r14,verify_sha256_digest
117
118 cghi %r10,1 /* checksum ve
119 je .return_old_kernel
120 cghi %r2,0 /* checksum ma
121 jne .disabled_wait
122
123 /* If the next kernel is a crash kerne
124 * the mem regions first.
125 */
126 cghi %r11,1 /* KEXEC_TYPE_CRASH */
127 je .start_crash_kernel
128
129 /* start normal kernel */
130 START_NEXT_KERNEL .base_crash 0
131
132 .return_old_kernel:
133 lmg %r6,%r15,gprregs-.base_crash(%
134 br %r14
135
136 .disabled_wait:
137 lpswe disabled_wait_psw-.base_crash(
138
139 .start_crash_kernel:
140 /* Location of purgatory_start in cras
141 larl %r0,.base_crash
142 larl %r1,purgatory_start
143 slgr %r0,%r1
144 lgr %r8,%r13
145 sgr %r8,%r0
146
147 /* Destination for this code i.e. end
148 larl %r0,purgatory_end
149 larl %r1,purgatory_start
150 slgr %r0,%r1
151 lg %r9,crash_size-.base_crash(%r1
152 sgr %r9,%r0
153
154 /* Destination in crash memory, i.e. s
155 lg %r10,crash_start-.base_crash(%
156 agr %r10,%r9
157
158 /* Buffer location (in crash memory) a
159 * behind the point of no return it ca
160 */
161 larl %r11,purgatory_end
162 larl %r12,stack
163 slgr %r11,%r12
164
165 MEMCPY %r12,%r9,%r11 /* dst -> (cr
166 MEMCPY %r9,%r8,%r11 /* self -> dst
167
168 /* Jump to new location. */
169 lgr %r7,%r9
170 larl %r0,.jump_to_dst
171 larl %r1,purgatory_start
172 slgr %r0,%r1
173 agr %r7,%r0
174 br %r7
175
176 .jump_to_dst:
177 basr %r13,0
178 .base_dst:
179
180 /* clear buffer */
181 MEMCPY %r12,%r10,%r11 /* (crash) buf
182
183 /* Load new buffer location after jump
184 larl %r7,stack
185 lgr %r0,%r7
186 larl %r1,purgatory_start
187 slgr %r0,%r1
188 agr %r10,%r0
189 MEMCPY %r10,%r7,%r11 /* (new) buf -
190
191 /* Now the code is set up to run from
192 * swapping the rest of crash memory n
193 *
194 * The registers will be used as follo
195 *
196 * %r0-%r4 reserved for macros de
197 * %r5-%r6 tmp registers
198 * %r7 pointer to current str
199 * %r8 index to iterate over
200 * %r9 pointer in crash memor
201 * %r10 pointer in old kernel
202 * %r11 total size (still) to
203 * %r12 pointer to buffer
204 */
205 lgr %r12,%r7
206 lgr %r11,%r9
207 lghi %r10,0
208 lg %r9,crash_start-.base_dst(%r13
209 lghi %r8,16 /* KEXEC_SEGMENTS_MAX
210 larl %r7,purgatory_sha_regions
211
212 j .loop_first
213
214 /* Loop over all purgatory_sha_regions
215 .loop_next:
216 aghi %r8,-1
217 cghi %r8,0
218 je .loop_out
219
220 aghi %r7,__KEXEC_SHA_REGION_SIZE
221
222 .loop_first:
223 lg %r5,__KEXEC_SHA_REGION_START(%
224 cghi %r5,0
225 je .loop_next
226
227 /* Copy [end last sha region, start cu
228 /* Note: kexec_sha_region->start point
229 sgr %r5,%r9
230 MEMCPY %r9,%r10,%r5
231
232 agr %r9,%r5
233 agr %r10,%r5
234 sgr %r11,%r5
235
236 /* Swap sha region */
237 lg %r6,__KEXEC_SHA_REGION_LEN(%r7
238 MEMSWAP %r9,%r10,%r12,%r6
239 sg %r11,__KEXEC_SHA_REGION_LEN(%r
240 j .loop_next
241
242 .loop_out:
243 /* Copy rest of crash memory */
244 MEMCPY %r9,%r10,%r11
245
246 /* start crash kernel */
247 START_NEXT_KERNEL .base_dst 1
248 SYM_CODE_END(purgatory_start)
249
250 SYM_DATA_LOCAL(load_psw_mask, .long
251 .balign 8
252 SYM_DATA_LOCAL(disabled_wait_psw, .quad
253 SYM_DATA_LOCAL(gprregs, .fill
254 SYM_DATA(purgatory_sha256_digest, .skip
255 SYM_DATA(purgatory_sha_regions, .skip
256 SYM_DATA(kernel_entry, .skip
257 SYM_DATA(kernel_type, .skip
258 SYM_DATA(crash_start, .skip
259 SYM_DATA(crash_size, .skip
260 .balign PAGE_SIZE
261 SYM_DATA_START_LOCAL(stack)
262 /* The buffer to move this code must b
263 .skip stack-purgatory_start
264 .balign PAGE_SIZE
265 SYM_DATA_END_LABEL(stack, SYM_L_LOCAL, purgato
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