Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 | /* SPDX-License-Identifier: GPL-2.0 */ /* * Copyright (C) 2014, 2015 Intel Corporation; author Matt Fleming * * Early support for invoking 32-bit EFI services from a 64-bit kernel. * * Because this thunking occurs before ExitBootServices() we have to * restore the firmware's 32-bit GDT and IDT before we make EFI service * calls. * * On the plus side, we don't have to worry about mangling 64-bit * addresses into 32-bits because we're executing with an identity * mapped pagetable and haven't transitioned to 64-bit virtual addresses * yet. */ #include <linux/linkage.h> #include <asm/asm-offsets.h> #include <asm/msr.h> #include <asm/page_types.h> #include <asm/processor-flags.h> #include <asm/segment.h> #include <asm/setup.h> .code64 .text /* * When booting in 64-bit mode on 32-bit EFI firmware, startup_64_mixed_mode() * is the first thing that runs after switching to long mode. Depending on * whether the EFI handover protocol or the compat entry point was used to * enter the kernel, it will either branch to the common 64-bit EFI stub * entrypoint efi_stub_entry() directly, or via the 64-bit EFI PE/COFF * entrypoint efi_pe_entry(). In the former case, the bootloader must provide a * struct bootparams pointer as the third argument, so the presence of such a * pointer is used to disambiguate. * * +--------------+ * +------------------+ +------------+ +------>| efi_pe_entry | * | efi32_pe_entry |---->| | | +-----------+--+ * +------------------+ | | +------+----------------+ | * | startup_32 |---->| startup_64_mixed_mode | | * +------------------+ | | +------+----------------+ | * | efi32_stub_entry |---->| | | | * +------------------+ +------------+ | | * V | * +------------+ +----------------+ | * | startup_64 |<----| efi_stub_entry |<--------+ * +------------+ +----------------+ */ SYM_FUNC_START(startup_64_mixed_mode) lea efi32_boot_args(%rip), %rdx mov 0(%rdx), %edi mov 4(%rdx), %esi /* Switch to the firmware's stack */ movl efi32_boot_sp(%rip), %esp andl $~7, %esp #ifdef CONFIG_EFI_HANDOVER_PROTOCOL mov 8(%rdx), %edx // saved bootparams pointer test %edx, %edx jnz efi_stub_entry #endif /* * efi_pe_entry uses MS calling convention, which requires 32 bytes of * shadow space on the stack even if all arguments are passed in * registers. We also need an additional 8 bytes for the space that * would be occupied by the return address, and this also results in * the correct stack alignment for entry. */ sub $40, %rsp mov %rdi, %rcx // MS calling convention mov %rsi, %rdx jmp efi_pe_entry SYM_FUNC_END(startup_64_mixed_mode) SYM_FUNC_START(__efi64_thunk) push %rbp push %rbx movl %ds, %eax push %rax movl %es, %eax push %rax movl %ss, %eax push %rax /* Copy args passed on stack */ movq 0x30(%rsp), %rbp movq 0x38(%rsp), %rbx movq 0x40(%rsp), %rax /* * Convert x86-64 ABI params to i386 ABI */ subq $64, %rsp movl %esi, 0x0(%rsp) movl %edx, 0x4(%rsp) movl %ecx, 0x8(%rsp) movl %r8d, 0xc(%rsp) movl %r9d, 0x10(%rsp) movl %ebp, 0x14(%rsp) movl %ebx, 0x18(%rsp) movl %eax, 0x1c(%rsp) leaq 0x20(%rsp), %rbx sgdt (%rbx) sidt 16(%rbx) leaq 1f(%rip), %rbp /* * Switch to IDT and GDT with 32-bit segments. These are the firmware * GDT and IDT that were installed when the kernel started executing. * The pointers were saved by the efi32_entry() routine below. * * Pass the saved DS selector to the 32-bit code, and use far return to * restore the saved CS selector. */ lidt efi32_boot_idt(%rip) lgdt efi32_boot_gdt(%rip) movzwl efi32_boot_ds(%rip), %edx movzwq efi32_boot_cs(%rip), %rax pushq %rax leaq efi_enter32(%rip), %rax pushq %rax lretq 1: addq $64, %rsp movq %rdi, %rax pop %rbx movl %ebx, %ss pop %rbx movl %ebx, %es pop %rbx movl %ebx, %ds /* Clear out 32-bit selector from FS and GS */ xorl %ebx, %ebx movl %ebx, %fs movl %ebx, %gs pop %rbx pop %rbp RET SYM_FUNC_END(__efi64_thunk) .code32 #ifdef CONFIG_EFI_HANDOVER_PROTOCOL SYM_FUNC_START(efi32_stub_entry) call 1f 1: popl %ecx leal (efi32_boot_args - 1b)(%ecx), %ebx /* Clear BSS */ xorl %eax, %eax leal (_bss - 1b)(%ecx), %edi leal (_ebss - 1b)(%ecx), %ecx subl %edi, %ecx shrl $2, %ecx cld rep stosl add $0x4, %esp /* Discard return address */ popl %ecx popl %edx popl %esi movl %esi, 8(%ebx) jmp efi32_entry SYM_FUNC_END(efi32_stub_entry) #endif /* * EFI service pointer must be in %edi. * * The stack should represent the 32-bit calling convention. */ SYM_FUNC_START_LOCAL(efi_enter32) /* Load firmware selector into data and stack segment registers */ movl %edx, %ds movl %edx, %es movl %edx, %fs movl %edx, %gs movl %edx, %ss /* Reload pgtables */ movl %cr3, %eax movl %eax, %cr3 /* Disable paging */ movl %cr0, %eax btrl $X86_CR0_PG_BIT, %eax movl %eax, %cr0 /* Disable long mode via EFER */ movl $MSR_EFER, %ecx rdmsr btrl $_EFER_LME, %eax wrmsr call *%edi /* We must preserve return value */ movl %eax, %edi /* * Some firmware will return with interrupts enabled. Be sure to * disable them before we switch GDTs and IDTs. */ cli lidtl 16(%ebx) lgdtl (%ebx) movl %cr4, %eax btsl $(X86_CR4_PAE_BIT), %eax movl %eax, %cr4 movl %cr3, %eax movl %eax, %cr3 movl $MSR_EFER, %ecx rdmsr btsl $_EFER_LME, %eax wrmsr xorl %eax, %eax lldt %ax pushl $__KERNEL_CS pushl %ebp /* Enable paging */ movl %cr0, %eax btsl $X86_CR0_PG_BIT, %eax movl %eax, %cr0 lret SYM_FUNC_END(efi_enter32) /* * This is the common EFI stub entry point for mixed mode. * * Arguments: %ecx image handle * %edx EFI system table pointer * * Since this is the point of no return for ordinary execution, no registers * are considered live except for the function parameters. [Note that the EFI * stub may still exit and return to the firmware using the Exit() EFI boot * service.] */ SYM_FUNC_START_LOCAL(efi32_entry) call 1f 1: pop %ebx /* Save firmware GDTR and code/data selectors */ sgdtl (efi32_boot_gdt - 1b)(%ebx) movw %cs, (efi32_boot_cs - 1b)(%ebx) movw %ds, (efi32_boot_ds - 1b)(%ebx) /* Store firmware IDT descriptor */ sidtl (efi32_boot_idt - 1b)(%ebx) /* Store firmware stack pointer */ movl %esp, (efi32_boot_sp - 1b)(%ebx) /* Store boot arguments */ leal (efi32_boot_args - 1b)(%ebx), %ebx movl %ecx, 0(%ebx) movl %edx, 4(%ebx) movb $0x0, 12(%ebx) // efi_is64 /* * Allocate some memory for a temporary struct boot_params, which only * needs the minimal pieces that startup_32() relies on. */ subl $PARAM_SIZE, %esp movl %esp, %esi movl $PAGE_SIZE, BP_kernel_alignment(%esi) movl $_end - 1b, BP_init_size(%esi) subl $startup_32 - 1b, BP_init_size(%esi) /* Disable paging */ movl %cr0, %eax btrl $X86_CR0_PG_BIT, %eax movl %eax, %cr0 jmp startup_32 SYM_FUNC_END(efi32_entry) /* * efi_status_t efi32_pe_entry(efi_handle_t image_handle, * efi_system_table_32_t *sys_table) */ SYM_FUNC_START(efi32_pe_entry) pushl %ebp movl %esp, %ebp pushl %ebx // save callee-save registers pushl %edi call verify_cpu // check for long mode support testl %eax, %eax movl $0x80000003, %eax // EFI_UNSUPPORTED jnz 2f movl 8(%ebp), %ecx // image_handle movl 12(%ebp), %edx // sys_table jmp efi32_entry // pass %ecx, %edx // no other registers remain live 2: popl %edi // restore callee-save registers popl %ebx leave RET SYM_FUNC_END(efi32_pe_entry) #ifdef CONFIG_EFI_HANDOVER_PROTOCOL .org efi32_stub_entry + 0x200 .code64 SYM_FUNC_START_NOALIGN(efi64_stub_entry) jmp efi_handover_entry SYM_FUNC_END(efi64_stub_entry) #endif .data .balign 8 SYM_DATA_START_LOCAL(efi32_boot_gdt) .word 0 .quad 0 SYM_DATA_END(efi32_boot_gdt) SYM_DATA_START_LOCAL(efi32_boot_idt) .word 0 .quad 0 SYM_DATA_END(efi32_boot_idt) SYM_DATA_LOCAL(efi32_boot_cs, .word 0) SYM_DATA_LOCAL(efi32_boot_ds, .word 0) SYM_DATA_LOCAL(efi32_boot_sp, .long 0) SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0) SYM_DATA(efi_is64, .byte 1) |