1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * relocate_kernel.S - put the kernel image in place to boot
4 * Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
7 #include <linux/linkage.h>
8 #include <asm/page_types.h>
10 #include <asm/processor-flags.h>
11 #include <asm/pgtable_types.h>
12 #include <asm/nospec-branch.h>
13 #include <asm/unwind_hints.h>
16 * Must be relocatable PIC code callable as a C function, in particular
17 * there must be a plain RET and not jump to return thunk.
20 #define PTR(x) (x << 3)
21 #define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
24 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
25 * ~ control_page + PAGE_SIZE are used as data storage and stack for
28 #define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
30 /* Minimal CPU state */
33 #define CR3 DATA(0x10)
34 #define CR4 DATA(0x18)
37 #define CP_PA_TABLE_PAGE DATA(0x20)
38 #define CP_PA_SWAP_PAGE DATA(0x28)
39 #define CP_PA_BACKUP_PAGES_MAP DATA(0x30)
44 SYM_CODE_START_NOALIGN(relocate_range)
45 SYM_CODE_START_NOALIGN(relocate_kernel)
46 UNWIND_HINT_END_OF_STACK
49 * %rdi indirection_page
52 * %rcx preserve_context
53 * %r8 host_mem_enc_active
56 /* Save the CPU context, used for jumping back */
65 movq PTR(VA_CONTROL_PAGE)(%rsi), %r11
74 /* Save CR4. Required to enable the right paging mode later. */
77 /* zero out flags, and disable interrupts */
81 /* Save SME active flag */
85 * get physical address of control page now
86 * this is impossible after page table switch
88 movq PTR(PA_CONTROL_PAGE)(%rsi), %r8
90 /* get physical address of page table now too */
91 movq PTR(PA_TABLE_PAGE)(%rsi), %r9
93 /* get physical address of swap page now */
94 movq PTR(PA_SWAP_PAGE)(%rsi), %r10
96 /* save some information for jumping back */
97 movq %r9, CP_PA_TABLE_PAGE(%r11)
98 movq %r10, CP_PA_SWAP_PAGE(%r11)
99 movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11)
101 /* Switch to the identity mapped page tables */
104 /* setup a new stack at the end of the physical control page */
105 lea PAGE_SIZE(%r8), %rsp
107 /* jump to identity mapped page */
108 addq $(identity_mapped - relocate_kernel), %r8
113 SYM_CODE_END(relocate_kernel)
115 SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
116 UNWIND_HINT_END_OF_STACK
117 /* set return address to 0 if not preserving context */
119 /* store the start address on the stack */
123 * Clear X86_CR4_CET (if it was set) such that we can clear CR0_WP
127 andq $~(X86_CR4_CET), %rax
131 * Set cr0 to a known state:
133 * - Alignment check disabled
134 * - Write protect disabled
136 * - Don't do FP software emulation.
137 * - Protected mode enabled
140 andq $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
141 orl $(X86_CR0_PG | X86_CR0_PE), %eax
145 * Set cr4 to a known state:
146 * - physical address extension enabled
147 * - 5-level paging, if it was enabled before
149 movl $X86_CR4_PAE, %eax
150 testq $X86_CR4_LA57, %r13
152 orl $X86_CR4_LA57, %eax
159 /* Flush the TLB (needed?) */
163 * If SME is active, there could be old encrypted cache line
164 * entries that will conflict with the now unencrypted memory
165 * used by kexec. Flush the caches before copying the kernel.
176 * To be certain of avoiding problems with self-modifying code
177 * I need to execute a serializing instruction here.
178 * So I flush the TLB by reloading %cr3 here, it's handy,
179 * and not processor dependent.
185 * set all of the registers to known values
213 leaq PAGE_SIZE(%r10), %rsp
214 ANNOTATE_RETPOLINE_SAFE
217 /* get the re-entry point of the peer system */
219 leaq relocate_kernel(%rip), %r8
220 movq CP_PA_SWAP_PAGE(%r8), %r10
221 movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
222 movq CP_PA_TABLE_PAGE(%r8), %rax
224 lea PAGE_SIZE(%r8), %rsp
226 movq $virtual_mapped, %rax
231 SYM_CODE_END(identity_mapped)
233 SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
234 UNWIND_HINT_END_OF_STACK
235 ANNOTATE_NOENDBR // RET target, above
255 SYM_CODE_END(virtual_mapped)
258 SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
259 UNWIND_HINT_END_OF_STACK
260 movq %rdi, %rcx /* Put the page_list in %rcx */
265 0: /* top, read another word for the indirection page */
270 testb $0x1, %cl /* is it a destination page? */
273 andq $0xfffffffffffff000, %rdi
276 testb $0x2, %cl /* is it an indirection page? */
279 andq $0xfffffffffffff000, %rbx
282 testb $0x4, %cl /* is it the done indicator? */
286 testb $0x8, %cl /* is it the source indicator? */
287 jz 0b /* Ignore it otherwise */
288 movq %rcx, %rsi /* For ever source page do a copy */
289 andq $0xfffffffffffff000, %rsi
308 lea PAGE_SIZE(%rax), %rsi
314 SYM_CODE_END(swap_pages)
316 .skip KEXEC_CONTROL_CODE_MAX_SIZE - (. - relocate_kernel), 0xcc
317 SYM_CODE_END(relocate_range);