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#include <asm/nospec-branch.h> 13#include <asm/unwind_hints.h> 14 15/* 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. 18 */ 19 20#define PTR(x) (x << 3) 21#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY) 22 23/* 24 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE 25 * ~ control_page + PAGE_SIZE are used as data storage and stack for 26 * jumping back 27 */ 28#define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset)) 29 30/* Minimal CPU state */ 31#define RSP DATA(0x0) 32#define CR0 DATA(0x8) 33#define CR3 DATA(0x10) 34#define CR4 DATA(0x18) 35 36/* other data */ 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) 40 41 .text 42 .align PAGE_SIZE 43 .code64 44SYM_CODE_START_NOALIGN(relocate_kernel) 45 UNWIND_HINT_EMPTY 46 /* 47 * %rdi indirection_page 48 * %rsi page_list 49 * %rdx start address 50 * %rcx preserve_context 51 * %r8 sme_active 52 */ 53 54 /* Save the CPU context, used for jumping back */ 55 pushq %rbx 56 pushq %rbp 57 pushq %r12 58 pushq %r13 59 pushq %r14 60 pushq %r15 61 pushf 62 63 movq PTR(VA_CONTROL_PAGE)(%rsi), %r11 64 movq %rsp, RSP(%r11) 65 movq %cr0, %rax 66 movq %rax, CR0(%r11) 67 movq %cr3, %rax 68 movq %rax, CR3(%r11) 69 movq %cr4, %rax 70 movq %rax, CR4(%r11) 71 72 /* Save CR4. Required to enable the right paging mode later. */ 73 movq %rax, %r13 74 75 /* zero out flags, and disable interrupts */ 76 pushq $0 77 popfq 78 79 /* Save SME active flag */ 80 movq %r8, %r12 81 82 /* 83 * get physical address of control page now 84 * this is impossible after page table switch 85 */ 86 movq PTR(PA_CONTROL_PAGE)(%rsi), %r8 87 88 /* get physical address of page table now too */ 89 movq PTR(PA_TABLE_PAGE)(%rsi), %r9 90 91 /* get physical address of swap page now */ 92 movq PTR(PA_SWAP_PAGE)(%rsi), %r10 93 94 /* save some information for jumping back */ 95 movq %r9, CP_PA_TABLE_PAGE(%r11) 96 movq %r10, CP_PA_SWAP_PAGE(%r11) 97 movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11) 98 99 /* Switch to the identity mapped page tables */ 100 movq %r9, %cr3 101 102 /* setup a new stack at the end of the physical control page */ 103 lea PAGE_SIZE(%r8), %rsp 104 105 /* jump to identity mapped page */ 106 addq $(identity_mapped - relocate_kernel), %r8 107 pushq %r8 108 ANNOTATE_UNRET_SAFE 109 ret 110 int3 111SYM_CODE_END(relocate_kernel) 112 113SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 114 UNWIND_HINT_EMPTY 115 /* set return address to 0 if not preserving context */ 116 pushq $0 117 /* store the start address on the stack */ 118 pushq %rdx 119 120 /* 121 * Set cr0 to a known state: 122 * - Paging enabled 123 * - Alignment check disabled 124 * - Write protect disabled 125 * - No task switch 126 * - Don't do FP software emulation. 127 * - Proctected mode enabled 128 */ 129 movq %cr0, %rax 130 andq $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax 131 orl $(X86_CR0_PG | X86_CR0_PE), %eax 132 movq %rax, %cr0 133 134 /* 135 * Set cr4 to a known state: 136 * - physical address extension enabled 137 * - 5-level paging, if it was enabled before 138 */ 139 movl $X86_CR4_PAE, %eax 140 testq $X86_CR4_LA57, %r13 141 jz 1f 142 orl $X86_CR4_LA57, %eax 1431: 144 movq %rax, %cr4 145 146 jmp 1f 1471: 148 149 /* Flush the TLB (needed?) */ 150 movq %r9, %cr3 151 152 /* 153 * If SME is active, there could be old encrypted cache line 154 * entries that will conflict with the now unencrypted memory 155 * used by kexec. Flush the caches before copying the kernel. 156 */ 157 testq %r12, %r12 158 jz 1f 159 wbinvd 1601: 161 162 movq %rcx, %r11 163 call swap_pages 164 165 /* 166 * To be certain of avoiding problems with self-modifying code 167 * I need to execute a serializing instruction here. 168 * So I flush the TLB by reloading %cr3 here, it's handy, 169 * and not processor dependent. 170 */ 171 movq %cr3, %rax 172 movq %rax, %cr3 173 174 /* 175 * set all of the registers to known values 176 * leave %rsp alone 177 */ 178 179 testq %r11, %r11 180 jnz 1f 181 xorl %eax, %eax 182 xorl %ebx, %ebx 183 xorl %ecx, %ecx 184 xorl %edx, %edx 185 xorl %esi, %esi 186 xorl %edi, %edi 187 xorl %ebp, %ebp 188 xorl %r8d, %r8d 189 xorl %r9d, %r9d 190 xorl %r10d, %r10d 191 xorl %r11d, %r11d 192 xorl %r12d, %r12d 193 xorl %r13d, %r13d 194 xorl %r14d, %r14d 195 xorl %r15d, %r15d 196 197 ANNOTATE_UNRET_SAFE 198 ret 199 int3 200 2011: 202 popq %rdx 203 leaq PAGE_SIZE(%r10), %rsp 204 ANNOTATE_RETPOLINE_SAFE 205 call *%rdx 206 207 /* get the re-entry point of the peer system */ 208 movq 0(%rsp), %rbp 209 leaq relocate_kernel(%rip), %r8 210 movq CP_PA_SWAP_PAGE(%r8), %r10 211 movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi 212 movq CP_PA_TABLE_PAGE(%r8), %rax 213 movq %rax, %cr3 214 lea PAGE_SIZE(%r8), %rsp 215 call swap_pages 216 movq $virtual_mapped, %rax 217 pushq %rax 218 ANNOTATE_UNRET_SAFE 219 ret 220 int3 221SYM_CODE_END(identity_mapped) 222 223SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped) 224 UNWIND_HINT_EMPTY 225 movq RSP(%r8), %rsp 226 movq CR4(%r8), %rax 227 movq %rax, %cr4 228 movq CR3(%r8), %rax 229 movq CR0(%r8), %r8 230 movq %rax, %cr3 231 movq %r8, %cr0 232 movq %rbp, %rax 233 234 popf 235 popq %r15 236 popq %r14 237 popq %r13 238 popq %r12 239 popq %rbp 240 popq %rbx 241 ANNOTATE_UNRET_SAFE 242 ret 243 int3 244SYM_CODE_END(virtual_mapped) 245 246 /* Do the copies */ 247SYM_CODE_START_LOCAL_NOALIGN(swap_pages) 248 UNWIND_HINT_EMPTY 249 movq %rdi, %rcx /* Put the page_list in %rcx */ 250 xorl %edi, %edi 251 xorl %esi, %esi 252 jmp 1f 253 2540: /* top, read another word for the indirection page */ 255 256 movq (%rbx), %rcx 257 addq $8, %rbx 2581: 259 testb $0x1, %cl /* is it a destination page? */ 260 jz 2f 261 movq %rcx, %rdi 262 andq $0xfffffffffffff000, %rdi 263 jmp 0b 2642: 265 testb $0x2, %cl /* is it an indirection page? */ 266 jz 2f 267 movq %rcx, %rbx 268 andq $0xfffffffffffff000, %rbx 269 jmp 0b 2702: 271 testb $0x4, %cl /* is it the done indicator? */ 272 jz 2f 273 jmp 3f 2742: 275 testb $0x8, %cl /* is it the source indicator? */ 276 jz 0b /* Ignore it otherwise */ 277 movq %rcx, %rsi /* For ever source page do a copy */ 278 andq $0xfffffffffffff000, %rsi 279 280 movq %rdi, %rdx 281 movq %rsi, %rax 282 283 movq %r10, %rdi 284 movl $512, %ecx 285 rep ; movsq 286 287 movq %rax, %rdi 288 movq %rdx, %rsi 289 movl $512, %ecx 290 rep ; movsq 291 292 movq %rdx, %rdi 293 movq %r10, %rsi 294 movl $512, %ecx 295 rep ; movsq 296 297 lea PAGE_SIZE(%rax), %rsi 298 jmp 0b 2993: 300 ANNOTATE_UNRET_SAFE 301 ret 302 int3 303SYM_CODE_END(swap_pages) 304 305 .globl kexec_control_code_size 306.set kexec_control_code_size, . - relocate_kernel 307