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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * relocate_kernel.S - put the kernel image in place to boot
4 * Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
5 */
6
7#include <linux/linkage.h>
8#include <asm/page_types.h>
9#include <asm/kexec.h>
10#include <asm/processor-flags.h>
11#include <asm/pgtable_types.h>
12
13/*
14 * Must be relocatable PIC code callable as a C function
15 */
16
17#define PTR(x) (x << 3)
18#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
19
20/*
21 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
22 * ~ control_page + PAGE_SIZE are used as data storage and stack for
23 * jumping back
24 */
25#define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
26
27/* Minimal CPU state */
28#define RSP DATA(0x0)
29#define CR0 DATA(0x8)
30#define CR3 DATA(0x10)
31#define CR4 DATA(0x18)
32
33/* other data */
34#define CP_PA_TABLE_PAGE DATA(0x20)
35#define CP_PA_SWAP_PAGE DATA(0x28)
36#define CP_PA_BACKUP_PAGES_MAP DATA(0x30)
37
38 .text
39 .align PAGE_SIZE
40 .code64
41 .globl relocate_kernel
42relocate_kernel:
43 /*
44 * %rdi indirection_page
45 * %rsi page_list
46 * %rdx start address
47 * %rcx preserve_context
48 * %r8 sme_active
49 */
50
51 /* Save the CPU context, used for jumping back */
52 pushq %rbx
53 pushq %rbp
54 pushq %r12
55 pushq %r13
56 pushq %r14
57 pushq %r15
58 pushf
59
60 movq PTR(VA_CONTROL_PAGE)(%rsi), %r11
61 movq %rsp, RSP(%r11)
62 movq %cr0, %rax
63 movq %rax, CR0(%r11)
64 movq %cr3, %rax
65 movq %rax, CR3(%r11)
66 movq %cr4, %rax
67 movq %rax, CR4(%r11)
68
69 /* Save CR4. Required to enable the right paging mode later. */
70 movq %rax, %r13
71
72 /* zero out flags, and disable interrupts */
73 pushq $0
74 popfq
75
76 /* Save SME active flag */
77 movq %r8, %r12
78
79 /*
80 * get physical address of control page now
81 * this is impossible after page table switch
82 */
83 movq PTR(PA_CONTROL_PAGE)(%rsi), %r8
84
85 /* get physical address of page table now too */
86 movq PTR(PA_TABLE_PAGE)(%rsi), %r9
87
88 /* get physical address of swap page now */
89 movq PTR(PA_SWAP_PAGE)(%rsi), %r10
90
91 /* save some information for jumping back */
92 movq %r9, CP_PA_TABLE_PAGE(%r11)
93 movq %r10, CP_PA_SWAP_PAGE(%r11)
94 movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11)
95
96 /* Switch to the identity mapped page tables */
97 movq %r9, %cr3
98
99 /* setup a new stack at the end of the physical control page */
100 lea PAGE_SIZE(%r8), %rsp
101
102 /* jump to identity mapped page */
103 addq $(identity_mapped - relocate_kernel), %r8
104 pushq %r8
105 ret
106
107identity_mapped:
108 /* set return address to 0 if not preserving context */
109 pushq $0
110 /* store the start address on the stack */
111 pushq %rdx
112
113 /*
114 * Set cr0 to a known state:
115 * - Paging enabled
116 * - Alignment check disabled
117 * - Write protect disabled
118 * - No task switch
119 * - Don't do FP software emulation.
120 * - Proctected mode enabled
121 */
122 movq %cr0, %rax
123 andq $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
124 orl $(X86_CR0_PG | X86_CR0_PE), %eax
125 movq %rax, %cr0
126
127 /*
128 * Set cr4 to a known state:
129 * - physical address extension enabled
130 * - 5-level paging, if it was enabled before
131 */
132 movl $X86_CR4_PAE, %eax
133 testq $X86_CR4_LA57, %r13
134 jz 1f
135 orl $X86_CR4_LA57, %eax
1361:
137 movq %rax, %cr4
138
139 jmp 1f
1401:
141
142 /* Flush the TLB (needed?) */
143 movq %r9, %cr3
144
145 /*
146 * If SME is active, there could be old encrypted cache line
147 * entries that will conflict with the now unencrypted memory
148 * used by kexec. Flush the caches before copying the kernel.
149 */
150 testq %r12, %r12
151 jz 1f
152 wbinvd
1531:
154
155 movq %rcx, %r11
156 call swap_pages
157
158 /*
159 * To be certain of avoiding problems with self-modifying code
160 * I need to execute a serializing instruction here.
161 * So I flush the TLB by reloading %cr3 here, it's handy,
162 * and not processor dependent.
163 */
164 movq %cr3, %rax
165 movq %rax, %cr3
166
167 /*
168 * set all of the registers to known values
169 * leave %rsp alone
170 */
171
172 testq %r11, %r11
173 jnz 1f
174 xorl %eax, %eax
175 xorl %ebx, %ebx
176 xorl %ecx, %ecx
177 xorl %edx, %edx
178 xorl %esi, %esi
179 xorl %edi, %edi
180 xorl %ebp, %ebp
181 xorl %r8d, %r8d
182 xorl %r9d, %r9d
183 xorl %r10d, %r10d
184 xorl %r11d, %r11d
185 xorl %r12d, %r12d
186 xorl %r13d, %r13d
187 xorl %r14d, %r14d
188 xorl %r15d, %r15d
189
190 ret
191
1921:
193 popq %rdx
194 leaq PAGE_SIZE(%r10), %rsp
195 call *%rdx
196
197 /* get the re-entry point of the peer system */
198 movq 0(%rsp), %rbp
199 call 1f
2001:
201 popq %r8
202 subq $(1b - relocate_kernel), %r8
203 movq CP_PA_SWAP_PAGE(%r8), %r10
204 movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
205 movq CP_PA_TABLE_PAGE(%r8), %rax
206 movq %rax, %cr3
207 lea PAGE_SIZE(%r8), %rsp
208 call swap_pages
209 movq $virtual_mapped, %rax
210 pushq %rax
211 ret
212
213virtual_mapped:
214 movq RSP(%r8), %rsp
215 movq CR4(%r8), %rax
216 movq %rax, %cr4
217 movq CR3(%r8), %rax
218 movq CR0(%r8), %r8
219 movq %rax, %cr3
220 movq %r8, %cr0
221 movq %rbp, %rax
222
223 popf
224 popq %r15
225 popq %r14
226 popq %r13
227 popq %r12
228 popq %rbp
229 popq %rbx
230 ret
231
232 /* Do the copies */
233swap_pages:
234 movq %rdi, %rcx /* Put the page_list in %rcx */
235 xorl %edi, %edi
236 xorl %esi, %esi
237 jmp 1f
238
2390: /* top, read another word for the indirection page */
240
241 movq (%rbx), %rcx
242 addq $8, %rbx
2431:
244 testb $0x1, %cl /* is it a destination page? */
245 jz 2f
246 movq %rcx, %rdi
247 andq $0xfffffffffffff000, %rdi
248 jmp 0b
2492:
250 testb $0x2, %cl /* is it an indirection page? */
251 jz 2f
252 movq %rcx, %rbx
253 andq $0xfffffffffffff000, %rbx
254 jmp 0b
2552:
256 testb $0x4, %cl /* is it the done indicator? */
257 jz 2f
258 jmp 3f
2592:
260 testb $0x8, %cl /* is it the source indicator? */
261 jz 0b /* Ignore it otherwise */
262 movq %rcx, %rsi /* For ever source page do a copy */
263 andq $0xfffffffffffff000, %rsi
264
265 movq %rdi, %rdx
266 movq %rsi, %rax
267
268 movq %r10, %rdi
269 movl $512, %ecx
270 rep ; movsq
271
272 movq %rax, %rdi
273 movq %rdx, %rsi
274 movl $512, %ecx
275 rep ; movsq
276
277 movq %rdx, %rdi
278 movq %r10, %rsi
279 movl $512, %ecx
280 rep ; movsq
281
282 lea PAGE_SIZE(%rax), %rsi
283 jmp 0b
2843:
285 ret
286
287 .globl kexec_control_code_size
288.set kexec_control_code_size, . - relocate_kernel
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * relocate_kernel.S - put the kernel image in place to boot
4 * Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
5 */
6
7#include <linux/linkage.h>
8#include <linux/stringify.h>
9#include <asm/alternative.h>
10#include <asm/page_types.h>
11#include <asm/kexec.h>
12#include <asm/processor-flags.h>
13#include <asm/pgtable_types.h>
14#include <asm/nospec-branch.h>
15#include <asm/unwind_hints.h>
16#include <asm/asm-offsets.h>
17
18/*
19 * Must be relocatable PIC code callable as a C function, in particular
20 * there must be a plain RET and not jump to return thunk.
21 */
22
23#define PTR(x) (x << 3)
24#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
25
26/*
27 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
28 * ~ control_page + PAGE_SIZE are used as data storage and stack for
29 * jumping back
30 */
31#define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
32
33/* Minimal CPU state */
34#define RSP DATA(0x0)
35#define CR0 DATA(0x8)
36#define CR3 DATA(0x10)
37#define CR4 DATA(0x18)
38
39/* other data */
40#define CP_PA_TABLE_PAGE DATA(0x20)
41#define CP_PA_SWAP_PAGE DATA(0x28)
42#define CP_PA_BACKUP_PAGES_MAP DATA(0x30)
43
44 .text
45 .align PAGE_SIZE
46 .code64
47SYM_CODE_START_NOALIGN(relocate_range)
48SYM_CODE_START_NOALIGN(relocate_kernel)
49 UNWIND_HINT_END_OF_STACK
50 ANNOTATE_NOENDBR
51 /*
52 * %rdi indirection_page
53 * %rsi page_list
54 * %rdx start address
55 * %rcx preserve_context
56 * %r8 host_mem_enc_active
57 */
58
59 /* Save the CPU context, used for jumping back */
60 pushq %rbx
61 pushq %rbp
62 pushq %r12
63 pushq %r13
64 pushq %r14
65 pushq %r15
66 pushf
67
68 movq PTR(VA_CONTROL_PAGE)(%rsi), %r11
69 movq %rsp, RSP(%r11)
70 movq %cr0, %rax
71 movq %rax, CR0(%r11)
72 movq %cr3, %rax
73 movq %rax, CR3(%r11)
74 movq %cr4, %rax
75 movq %rax, CR4(%r11)
76
77 /* Save CR4. Required to enable the right paging mode later. */
78 movq %rax, %r13
79
80 /* zero out flags, and disable interrupts */
81 pushq $0
82 popfq
83
84 /* Save SME active flag */
85 movq %r8, %r12
86
87 /*
88 * get physical address of control page now
89 * this is impossible after page table switch
90 */
91 movq PTR(PA_CONTROL_PAGE)(%rsi), %r8
92
93 /* get physical address of page table now too */
94 movq PTR(PA_TABLE_PAGE)(%rsi), %r9
95
96 /* get physical address of swap page now */
97 movq PTR(PA_SWAP_PAGE)(%rsi), %r10
98
99 /* save some information for jumping back */
100 movq %r9, CP_PA_TABLE_PAGE(%r11)
101 movq %r10, CP_PA_SWAP_PAGE(%r11)
102 movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11)
103
104 /* Switch to the identity mapped page tables */
105 movq %r9, %cr3
106
107 /* setup a new stack at the end of the physical control page */
108 lea PAGE_SIZE(%r8), %rsp
109
110 /* jump to identity mapped page */
111 addq $(identity_mapped - relocate_kernel), %r8
112 pushq %r8
113 ANNOTATE_UNRET_SAFE
114 ret
115 int3
116SYM_CODE_END(relocate_kernel)
117
118SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
119 UNWIND_HINT_END_OF_STACK
120 /* set return address to 0 if not preserving context */
121 pushq $0
122 /* store the start address on the stack */
123 pushq %rdx
124
125 /*
126 * Clear X86_CR4_CET (if it was set) such that we can clear CR0_WP
127 * below.
128 */
129 movq %cr4, %rax
130 andq $~(X86_CR4_CET), %rax
131 movq %rax, %cr4
132
133 /*
134 * Set cr0 to a known state:
135 * - Paging enabled
136 * - Alignment check disabled
137 * - Write protect disabled
138 * - No task switch
139 * - Don't do FP software emulation.
140 * - Protected mode enabled
141 */
142 movq %cr0, %rax
143 andq $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
144 orl $(X86_CR0_PG | X86_CR0_PE), %eax
145 movq %rax, %cr0
146
147 /*
148 * Set cr4 to a known state:
149 * - physical address extension enabled
150 * - 5-level paging, if it was enabled before
151 * - Machine check exception on TDX guest, if it was enabled before.
152 * Clearing MCE might not be allowed in TDX guests, depending on setup.
153 *
154 * Use R13 that contains the original CR4 value, read in relocate_kernel().
155 * PAE is always set in the original CR4.
156 */
157 andl $(X86_CR4_PAE | X86_CR4_LA57), %r13d
158 ALTERNATIVE "", __stringify(orl $X86_CR4_MCE, %r13d), X86_FEATURE_TDX_GUEST
159 movq %r13, %cr4
160
161 /* Flush the TLB (needed?) */
162 movq %r9, %cr3
163
164 /*
165 * If SME is active, there could be old encrypted cache line
166 * entries that will conflict with the now unencrypted memory
167 * used by kexec. Flush the caches before copying the kernel.
168 */
169 testq %r12, %r12
170 jz .Lsme_off
171 wbinvd
172.Lsme_off:
173
174 /* Save the preserve_context to %r11 as swap_pages clobbers %rcx. */
175 movq %rcx, %r11
176 call swap_pages
177
178 /*
179 * To be certain of avoiding problems with self-modifying code
180 * I need to execute a serializing instruction here.
181 * So I flush the TLB by reloading %cr3 here, it's handy,
182 * and not processor dependent.
183 */
184 movq %cr3, %rax
185 movq %rax, %cr3
186
187 /*
188 * set all of the registers to known values
189 * leave %rsp alone
190 */
191
192 testq %r11, %r11
193 jnz .Lrelocate
194 xorl %eax, %eax
195 xorl %ebx, %ebx
196 xorl %ecx, %ecx
197 xorl %edx, %edx
198 xorl %esi, %esi
199 xorl %edi, %edi
200 xorl %ebp, %ebp
201 xorl %r8d, %r8d
202 xorl %r9d, %r9d
203 xorl %r10d, %r10d
204 xorl %r11d, %r11d
205 xorl %r12d, %r12d
206 xorl %r13d, %r13d
207 xorl %r14d, %r14d
208 xorl %r15d, %r15d
209
210 ANNOTATE_UNRET_SAFE
211 ret
212 int3
213
214.Lrelocate:
215 popq %rdx
216 leaq PAGE_SIZE(%r10), %rsp
217 ANNOTATE_RETPOLINE_SAFE
218 call *%rdx
219
220 /* get the re-entry point of the peer system */
221 movq 0(%rsp), %rbp
222 leaq relocate_kernel(%rip), %r8
223 movq CP_PA_SWAP_PAGE(%r8), %r10
224 movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
225 movq CP_PA_TABLE_PAGE(%r8), %rax
226 movq %rax, %cr3
227 lea PAGE_SIZE(%r8), %rsp
228 call swap_pages
229 movq $virtual_mapped, %rax
230 pushq %rax
231 ANNOTATE_UNRET_SAFE
232 ret
233 int3
234SYM_CODE_END(identity_mapped)
235
236SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
237 UNWIND_HINT_END_OF_STACK
238 ANNOTATE_NOENDBR // RET target, above
239 movq RSP(%r8), %rsp
240 movq CR4(%r8), %rax
241 movq %rax, %cr4
242 movq CR3(%r8), %rax
243 movq CR0(%r8), %r8
244 movq %rax, %cr3
245 movq %r8, %cr0
246
247#ifdef CONFIG_KEXEC_JUMP
248 /* Saved in save_processor_state. */
249 movq $saved_context, %rax
250 lgdt saved_context_gdt_desc(%rax)
251#endif
252
253 movq %rbp, %rax
254
255 popf
256 popq %r15
257 popq %r14
258 popq %r13
259 popq %r12
260 popq %rbp
261 popq %rbx
262 ANNOTATE_UNRET_SAFE
263 ret
264 int3
265SYM_CODE_END(virtual_mapped)
266
267 /* Do the copies */
268SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
269 UNWIND_HINT_END_OF_STACK
270 movq %rdi, %rcx /* Put the indirection_page in %rcx */
271 xorl %edi, %edi
272 xorl %esi, %esi
273 jmp 1f
274
2750: /* top, read another word for the indirection page */
276
277 movq (%rbx), %rcx
278 addq $8, %rbx
2791:
280 testb $0x1, %cl /* is it a destination page? */
281 jz 2f
282 movq %rcx, %rdi
283 andq $0xfffffffffffff000, %rdi
284 jmp 0b
2852:
286 testb $0x2, %cl /* is it an indirection page? */
287 jz 2f
288 movq %rcx, %rbx
289 andq $0xfffffffffffff000, %rbx
290 jmp 0b
2912:
292 testb $0x4, %cl /* is it the done indicator? */
293 jz 2f
294 jmp 3f
2952:
296 testb $0x8, %cl /* is it the source indicator? */
297 jz 0b /* Ignore it otherwise */
298 movq %rcx, %rsi /* For ever source page do a copy */
299 andq $0xfffffffffffff000, %rsi
300
301 movq %rdi, %rdx /* Save destination page to %rdx */
302 movq %rsi, %rax /* Save source page to %rax */
303
304 /* copy source page to swap page */
305 movq %r10, %rdi
306 movl $512, %ecx
307 rep ; movsq
308
309 /* copy destination page to source page */
310 movq %rax, %rdi
311 movq %rdx, %rsi
312 movl $512, %ecx
313 rep ; movsq
314
315 /* copy swap page to destination page */
316 movq %rdx, %rdi
317 movq %r10, %rsi
318 movl $512, %ecx
319 rep ; movsq
320
321 lea PAGE_SIZE(%rax), %rsi
322 jmp 0b
3233:
324 ANNOTATE_UNRET_SAFE
325 ret
326 int3
327SYM_CODE_END(swap_pages)
328
329 .skip KEXEC_CONTROL_CODE_MAX_SIZE - (. - relocate_kernel), 0xcc
330SYM_CODE_END(relocate_range);