1/* SPDX-License-Identifier: GPL-2.0 */ 2 3/* 4 * Copyright C 2016, Oracle and/or its affiliates. All rights reserved. 5 */ 6 7 .code32 8 .text 9#ifdef CONFIG_X86_32 10#define _pa(x) ((x) - __START_KERNEL_map) 11#endif 12#define rva(x) ((x) - pvh_start_xen) 13 14#include <linux/elfnote.h> 15#include <linux/init.h> 16#include <linux/linkage.h> 17#include <asm/desc_defs.h> 18#include <asm/segment.h> 19#include <asm/asm.h> 20#include <asm/boot.h> 21#include <asm/pgtable.h> 22#include <asm/processor-flags.h> 23#include <asm/msr.h> 24#include <asm/nospec-branch.h> 25#include <xen/interface/elfnote.h> 26 27 __HEAD 28 29/* 30 * Entry point for PVH guests. 31 * 32 * Xen ABI specifies the following register state when we come here: 33 * 34 * - `ebx`: contains the physical memory address where the loader has placed 35 * the boot start info structure. 36 * - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared. 37 * - `cr4`: all bits are cleared. 38 * - `cs `: must be a 32-bit read/execute code segment with a base of `0` 39 * and a limit of `0xFFFFFFFF`. The selector value is unspecified. 40 * - `ds`, `es`: must be a 32-bit read/write data segment with a base of 41 * `0` and a limit of `0xFFFFFFFF`. The selector values are all 42 * unspecified. 43 * - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit 44 * of '0x67'. 45 * - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared. 46 * Bit 8 (TF) must be cleared. Other bits are all unspecified. 47 * 48 * All other processor registers and flag bits are unspecified. The OS is in 49 * charge of setting up its own stack, GDT and IDT. 50 */ 51 52#define PVH_GDT_ENTRY_CS 1 53#define PVH_GDT_ENTRY_DS 2 54#define PVH_CS_SEL (PVH_GDT_ENTRY_CS * 8) 55#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8) 56 57SYM_CODE_START(pvh_start_xen) 58 UNWIND_HINT_END_OF_STACK 59 cld 60 61 /* 62 * See the comment for startup_32 for more details. We need to 63 * execute a call to get the execution address to be position 64 * independent, but we don't have a stack. Save and restore the 65 * magic field of start_info in ebx, and use that as the stack. 66 */ 67 mov (%ebx), %eax 68 leal 4(%ebx), %esp 69 ANNOTATE_INTRA_FUNCTION_CALL 70 call 1f 711: popl %ebp 72 mov %eax, (%ebx) 73 subl $rva(1b), %ebp 74 movl $0, %esp 75 76 leal rva(gdt)(%ebp), %eax 77 addl %eax, 2(%eax) 78 lgdt (%eax) 79 80 mov $PVH_DS_SEL,%eax 81 mov %eax,%ds 82 mov %eax,%es 83 mov %eax,%ss 84 85 /* Stash hvm_start_info. */ 86 leal rva(pvh_start_info)(%ebp), %edi 87 mov %ebx, %esi 88 movl rva(pvh_start_info_sz)(%ebp), %ecx 89 shr $2,%ecx 90 rep 91 movsl 92 93 leal rva(early_stack_end)(%ebp), %esp 94 95 /* Enable PAE mode. */ 96 mov %cr4, %eax 97 orl $X86_CR4_PAE, %eax 98 mov %eax, %cr4 99 100#ifdef CONFIG_X86_64 101 /* Enable Long mode. */ 102 mov $MSR_EFER, %ecx 103 rdmsr 104 btsl $_EFER_LME, %eax 105 wrmsr 106 107 /* 108 * Reuse the non-relocatable symbol emitted for the ELF note to 109 * subtract the build time physical address of pvh_start_xen() from 110 * its actual runtime address, without relying on absolute 32-bit ELF 111 * relocations, as these are not supported by the linker when running 112 * in -pie mode, and should be avoided in .head.text in general. 113 */ 114 mov %ebp, %ebx 115 subl rva(xen_elfnote_phys32_entry)(%ebp), %ebx 116 jz .Lpagetable_done 117 118 /* 119 * Store the resulting load offset in phys_base. __pa() needs 120 * phys_base set to calculate the hypercall page in xen_pvh_init(). 121 */ 122 movl %ebx, rva(phys_base)(%ebp) 123 124 /* Fixup page-tables for relocation. */ 125 leal rva(pvh_init_top_pgt)(%ebp), %edi 126 movl $PTRS_PER_PGD, %ecx 1272: 128 testl $_PAGE_PRESENT, 0x00(%edi) 129 jz 1f 130 addl %ebx, 0x00(%edi) 1311: 132 addl $8, %edi 133 decl %ecx 134 jnz 2b 135 136 /* L3 ident has a single entry. */ 137 leal rva(pvh_level3_ident_pgt)(%ebp), %edi 138 addl %ebx, 0x00(%edi) 139 140 leal rva(pvh_level3_kernel_pgt)(%ebp), %edi 141 addl %ebx, (PAGE_SIZE - 16)(%edi) 142 addl %ebx, (PAGE_SIZE - 8)(%edi) 143 144 /* pvh_level2_ident_pgt is fine - large pages */ 145 146 /* pvh_level2_kernel_pgt needs adjustment - large pages */ 147 leal rva(pvh_level2_kernel_pgt)(%ebp), %edi 148 movl $PTRS_PER_PMD, %ecx 1492: 150 testl $_PAGE_PRESENT, 0x00(%edi) 151 jz 1f 152 addl %ebx, 0x00(%edi) 1531: 154 addl $8, %edi 155 decl %ecx 156 jnz 2b 157 158.Lpagetable_done: 159 /* Enable pre-constructed page tables. */ 160 leal rva(pvh_init_top_pgt)(%ebp), %eax 161 mov %eax, %cr3 162 mov $(X86_CR0_PG | X86_CR0_PE), %eax 163 mov %eax, %cr0 164 165 /* Jump to 64-bit mode. */ 166 pushl $PVH_CS_SEL 167 leal rva(1f)(%ebp), %eax 168 pushl %eax 169 lretl 170 171 /* 64-bit entry point. */ 172 .code64 1731: 174 UNWIND_HINT_END_OF_STACK 175 176 /* Set base address in stack canary descriptor. */ 177 mov $MSR_GS_BASE,%ecx 178 leal canary(%rip), %eax 179 xor %edx, %edx 180 wrmsr 181 182 /* Call xen_prepare_pvh() via the kernel virtual mapping */ 183 leaq xen_prepare_pvh(%rip), %rax 184 subq phys_base(%rip), %rax 185 addq $__START_KERNEL_map, %rax 186 ANNOTATE_RETPOLINE_SAFE 187 call *%rax 188 189 /* startup_64 expects boot_params in %rsi. */ 190 lea pvh_bootparams(%rip), %rsi 191 jmp startup_64 192 193#else /* CONFIG_X86_64 */ 194 195 call mk_early_pgtbl_32 196 197 mov $_pa(initial_page_table), %eax 198 mov %eax, %cr3 199 200 mov %cr0, %eax 201 or $(X86_CR0_PG | X86_CR0_PE), %eax 202 mov %eax, %cr0 203 204 ljmp $PVH_CS_SEL, $1f 2051: 206 call xen_prepare_pvh 207 mov $_pa(pvh_bootparams), %esi 208 209 /* startup_32 doesn't expect paging and PAE to be on. */ 210 ljmp $PVH_CS_SEL, $_pa(2f) 2112: 212 mov %cr0, %eax 213 and $~X86_CR0_PG, %eax 214 mov %eax, %cr0 215 mov %cr4, %eax 216 and $~X86_CR4_PAE, %eax 217 mov %eax, %cr4 218 219 ljmp $PVH_CS_SEL, $_pa(startup_32) 220#endif 221SYM_CODE_END(pvh_start_xen) 222 223 .section ".init.data","aw" 224 .balign 8 225SYM_DATA_START_LOCAL(gdt) 226 .word gdt_end - gdt_start - 1 227 .long gdt_start - gdt 228 .word 0 229SYM_DATA_END(gdt) 230SYM_DATA_START_LOCAL(gdt_start) 231 .quad 0x0000000000000000 /* NULL descriptor */ 232#ifdef CONFIG_X86_64 233 .quad GDT_ENTRY(DESC_CODE64, 0, 0xfffff) /* PVH_CS_SEL */ 234#else 235 .quad GDT_ENTRY(DESC_CODE32, 0, 0xfffff) /* PVH_CS_SEL */ 236#endif 237 .quad GDT_ENTRY(DESC_DATA32, 0, 0xfffff) /* PVH_DS_SEL */ 238SYM_DATA_END_LABEL(gdt_start, SYM_L_LOCAL, gdt_end) 239 240 .balign 16 241SYM_DATA_LOCAL(canary, .fill 48, 1, 0) 242 243SYM_DATA_START_LOCAL(early_stack) 244 .fill BOOT_STACK_SIZE, 1, 0 245SYM_DATA_END_LABEL(early_stack, SYM_L_LOCAL, early_stack_end) 246 247#ifdef CONFIG_X86_64 248/* 249 * Xen PVH needs a set of identity mapped and kernel high mapping 250 * page tables. pvh_start_xen starts running on the identity mapped 251 * page tables, but xen_prepare_pvh calls into the high mapping. 252 * These page tables need to be relocatable and are only used until 253 * startup_64 transitions to init_top_pgt. 254 */ 255SYM_DATA_START_PAGE_ALIGNED(pvh_init_top_pgt) 256 .quad pvh_level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 257 .org pvh_init_top_pgt + L4_PAGE_OFFSET * 8, 0 258 .quad pvh_level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 259 .org pvh_init_top_pgt + L4_START_KERNEL * 8, 0 260 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */ 261 .quad pvh_level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 262SYM_DATA_END(pvh_init_top_pgt) 263 264SYM_DATA_START_PAGE_ALIGNED(pvh_level3_ident_pgt) 265 .quad pvh_level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 266 .fill 511, 8, 0 267SYM_DATA_END(pvh_level3_ident_pgt) 268SYM_DATA_START_PAGE_ALIGNED(pvh_level2_ident_pgt) 269 /* 270 * Since I easily can, map the first 1G. 271 * Don't set NX because code runs from these pages. 272 * 273 * Note: This sets _PAGE_GLOBAL despite whether 274 * the CPU supports it or it is enabled. But, 275 * the CPU should ignore the bit. 276 */ 277 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD) 278SYM_DATA_END(pvh_level2_ident_pgt) 279SYM_DATA_START_PAGE_ALIGNED(pvh_level3_kernel_pgt) 280 .fill L3_START_KERNEL, 8, 0 281 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */ 282 .quad pvh_level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 283 .quad 0 /* no fixmap */ 284SYM_DATA_END(pvh_level3_kernel_pgt) 285 286SYM_DATA_START_PAGE_ALIGNED(pvh_level2_kernel_pgt) 287 /* 288 * Kernel high mapping. 289 * 290 * The kernel code+data+bss must be located below KERNEL_IMAGE_SIZE in 291 * virtual address space, which is 1 GiB if RANDOMIZE_BASE is enabled, 292 * 512 MiB otherwise. 293 * 294 * (NOTE: after that starts the module area, see MODULES_VADDR.) 295 * 296 * This table is eventually used by the kernel during normal runtime. 297 * Care must be taken to clear out undesired bits later, like _PAGE_RW 298 * or _PAGE_GLOBAL in some cases. 299 */ 300 PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE / PMD_SIZE) 301SYM_DATA_END(pvh_level2_kernel_pgt) 302 303 ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_RELOC, 304 .long CONFIG_PHYSICAL_ALIGN; 305 .long LOAD_PHYSICAL_ADDR; 306 .long KERNEL_IMAGE_SIZE - 1) 307#endif 308 309 ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, .global xen_elfnote_phys32_entry; 310 xen_elfnote_phys32_entry: _ASM_PTR xen_elfnote_phys32_entry_value - .) 311