1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2014, 2015 Intel Corporation;
4 *
5 * Early support for invoking 32-bit EFI servi
6 *
7 * Because this thunking occurs before ExitBoo
8 * restore the firmware's 32-bit GDT and IDT b
9 * calls.
10 *
11 * On the plus side, we don't have to worry ab
12 * addresses into 32-bits because we're execut
13 * mapped pagetable and haven't transitioned t
14 * yet.
15 */
16
17 #include <linux/linkage.h>
18 #include <asm/asm-offsets.h>
19 #include <asm/msr.h>
20 #include <asm/page_types.h>
21 #include <asm/processor-flags.h>
22 #include <asm/segment.h>
23 #include <asm/setup.h>
24
25 .code64
26 .text
27 /*
28 * When booting in 64-bit mode on 32-bit EFI f
29 * is the first thing that runs after switchin
30 * whether the EFI handover protocol or the co
31 * enter the kernel, it will either branch to
32 * entrypoint efi_stub_entry() directly, or vi
33 * entrypoint efi_pe_entry(). In the former ca
34 * struct bootparams pointer as the third argu
35 * pointer is used to disambiguate.
36 *
37 *
38 * +------------------+ +------------+
39 * | efi32_pe_entry |---->| |
40 * +------------------+ | |
41 * | startup_32 |---
42 * +------------------+ | |
43 * | efi32_stub_entry |---->| |
44 * +------------------+ +------------+
45 *
46 * +------------+
47 * | startup_64 |<--
48 * +------------+
49 */
50 SYM_FUNC_START(startup_64_mixed_mode)
51 lea efi32_boot_args(%rip), %rdx
52 mov 0(%rdx), %edi
53 mov 4(%rdx), %esi
54
55 /* Switch to the firmware's stack */
56 movl efi32_boot_sp(%rip), %esp
57 andl $~7, %esp
58
59 #ifdef CONFIG_EFI_HANDOVER_PROTOCOL
60 mov 8(%rdx), %edx // sav
61 test %edx, %edx
62 jnz efi_stub_entry
63 #endif
64 /*
65 * efi_pe_entry uses MS calling conven
66 * shadow space on the stack even if a
67 * registers. We also need an addition
68 * would be occupied by the return add
69 * the correct stack alignment for ent
70 */
71 sub $40, %rsp
72 mov %rdi, %rcx // MS
73 mov %rsi, %rdx
74 jmp efi_pe_entry
75 SYM_FUNC_END(startup_64_mixed_mode)
76
77 SYM_FUNC_START(__efi64_thunk)
78 push %rbp
79 push %rbx
80
81 movl %ds, %eax
82 push %rax
83 movl %es, %eax
84 push %rax
85 movl %ss, %eax
86 push %rax
87
88 /* Copy args passed on stack */
89 movq 0x30(%rsp), %rbp
90 movq 0x38(%rsp), %rbx
91 movq 0x40(%rsp), %rax
92
93 /*
94 * Convert x86-64 ABI params to i386 A
95 */
96 subq $64, %rsp
97 movl %esi, 0x0(%rsp)
98 movl %edx, 0x4(%rsp)
99 movl %ecx, 0x8(%rsp)
100 movl %r8d, 0xc(%rsp)
101 movl %r9d, 0x10(%rsp)
102 movl %ebp, 0x14(%rsp)
103 movl %ebx, 0x18(%rsp)
104 movl %eax, 0x1c(%rsp)
105
106 leaq 0x20(%rsp), %rbx
107 sgdt (%rbx)
108 sidt 16(%rbx)
109
110 leaq 1f(%rip), %rbp
111
112 /*
113 * Switch to IDT and GDT with 32-bit s
114 * GDT and IDT that were installed whe
115 * The pointers were saved by the efi3
116 *
117 * Pass the saved DS selector to the 3
118 * restore the saved CS selector.
119 */
120 lidt efi32_boot_idt(%rip)
121 lgdt efi32_boot_gdt(%rip)
122
123 movzwl efi32_boot_ds(%rip), %edx
124 movzwq efi32_boot_cs(%rip), %rax
125 pushq %rax
126 leaq efi_enter32(%rip), %rax
127 pushq %rax
128 lretq
129
130 1: addq $64, %rsp
131 movq %rdi, %rax
132
133 pop %rbx
134 movl %ebx, %ss
135 pop %rbx
136 movl %ebx, %es
137 pop %rbx
138 movl %ebx, %ds
139 /* Clear out 32-bit selector from FS a
140 xorl %ebx, %ebx
141 movl %ebx, %fs
142 movl %ebx, %gs
143
144 pop %rbx
145 pop %rbp
146 RET
147 SYM_FUNC_END(__efi64_thunk)
148
149 .code32
150 #ifdef CONFIG_EFI_HANDOVER_PROTOCOL
151 SYM_FUNC_START(efi32_stub_entry)
152 call 1f
153 1: popl %ecx
154 leal (efi32_boot_args - 1b)(%ecx),
155
156 /* Clear BSS */
157 xorl %eax, %eax
158 leal (_bss - 1b)(%ecx), %edi
159 leal (_ebss - 1b)(%ecx), %ecx
160 subl %edi, %ecx
161 shrl $2, %ecx
162 cld
163 rep stosl
164
165 add $0x4, %esp /* Dis
166 popl %ecx
167 popl %edx
168 popl %esi
169 movl %esi, 8(%ebx)
170 jmp efi32_entry
171 SYM_FUNC_END(efi32_stub_entry)
172 #endif
173
174 /*
175 * EFI service pointer must be in %edi.
176 *
177 * The stack should represent the 32-bit calli
178 */
179 SYM_FUNC_START_LOCAL(efi_enter32)
180 /* Load firmware selector into data an
181 movl %edx, %ds
182 movl %edx, %es
183 movl %edx, %fs
184 movl %edx, %gs
185 movl %edx, %ss
186
187 /* Reload pgtables */
188 movl %cr3, %eax
189 movl %eax, %cr3
190
191 /* Disable paging */
192 movl %cr0, %eax
193 btrl $X86_CR0_PG_BIT, %eax
194 movl %eax, %cr0
195
196 /* Disable long mode via EFER */
197 movl $MSR_EFER, %ecx
198 rdmsr
199 btrl $_EFER_LME, %eax
200 wrmsr
201
202 call *%edi
203
204 /* We must preserve return value */
205 movl %eax, %edi
206
207 /*
208 * Some firmware will return with inte
209 * disable them before we switch GDTs
210 */
211 cli
212
213 lidtl 16(%ebx)
214 lgdtl (%ebx)
215
216 movl %cr4, %eax
217 btsl $(X86_CR4_PAE_BIT), %eax
218 movl %eax, %cr4
219
220 movl %cr3, %eax
221 movl %eax, %cr3
222
223 movl $MSR_EFER, %ecx
224 rdmsr
225 btsl $_EFER_LME, %eax
226 wrmsr
227
228 xorl %eax, %eax
229 lldt %ax
230
231 pushl $__KERNEL_CS
232 pushl %ebp
233
234 /* Enable paging */
235 movl %cr0, %eax
236 btsl $X86_CR0_PG_BIT, %eax
237 movl %eax, %cr0
238 lret
239 SYM_FUNC_END(efi_enter32)
240
241 /*
242 * This is the common EFI stub entry point for
243 *
244 * Arguments: %ecx image handle
245 * %edx EFI system table point
246 *
247 * Since this is the point of no return for or
248 * are considered live except for the function
249 * stub may still exit and return to the firmw
250 * service.]
251 */
252 SYM_FUNC_START_LOCAL(efi32_entry)
253 call 1f
254 1: pop %ebx
255
256 /* Save firmware GDTR and code/data se
257 sgdtl (efi32_boot_gdt - 1b)(%ebx)
258 movw %cs, (efi32_boot_cs - 1b)(%ebx
259 movw %ds, (efi32_boot_ds - 1b)(%ebx
260
261 /* Store firmware IDT descriptor */
262 sidtl (efi32_boot_idt - 1b)(%ebx)
263
264 /* Store firmware stack pointer */
265 movl %esp, (efi32_boot_sp - 1b)(%eb
266
267 /* Store boot arguments */
268 leal (efi32_boot_args - 1b)(%ebx),
269 movl %ecx, 0(%ebx)
270 movl %edx, 4(%ebx)
271 movb $0x0, 12(%ebx) // efi
272
273 /*
274 * Allocate some memory for a temporar
275 * needs the minimal pieces that start
276 */
277 subl $PARAM_SIZE, %esp
278 movl %esp, %esi
279 movl $PAGE_SIZE, BP_kernel_alignmen
280 movl $_end - 1b, BP_init_size(%esi)
281 subl $startup_32 - 1b, BP_init_size
282
283 /* Disable paging */
284 movl %cr0, %eax
285 btrl $X86_CR0_PG_BIT, %eax
286 movl %eax, %cr0
287
288 jmp startup_32
289 SYM_FUNC_END(efi32_entry)
290
291 /*
292 * efi_status_t efi32_pe_entry(efi_handle_t im
293 * efi_system_tabl
294 */
295 SYM_FUNC_START(efi32_pe_entry)
296 pushl %ebp
297 movl %esp, %ebp
298 pushl %ebx
299 pushl %edi
300
301 call verify_cpu
302 testl %eax, %eax
303 movl $0x80000003, %eax
304 jnz 2f
305
306 movl 8(%ebp), %ecx
307 movl 12(%ebp), %edx
308 jmp efi32_entry
309
310
311 2: popl %edi
312 popl %ebx
313 leave
314 RET
315 SYM_FUNC_END(efi32_pe_entry)
316
317 #ifdef CONFIG_EFI_HANDOVER_PROTOCOL
318 .org efi32_stub_entry + 0x200
319 .code64
320 SYM_FUNC_START_NOALIGN(efi64_stub_entry)
321 jmp efi_handover_entry
322 SYM_FUNC_END(efi64_stub_entry)
323 #endif
324
325 .data
326 .balign 8
327 SYM_DATA_START_LOCAL(efi32_boot_gdt)
328 .word 0
329 .quad 0
330 SYM_DATA_END(efi32_boot_gdt)
331
332 SYM_DATA_START_LOCAL(efi32_boot_idt)
333 .word 0
334 .quad 0
335 SYM_DATA_END(efi32_boot_idt)
336
337 SYM_DATA_LOCAL(efi32_boot_cs, .word 0)
338 SYM_DATA_LOCAL(efi32_boot_ds, .word 0)
339 SYM_DATA_LOCAL(efi32_boot_sp, .long 0)
340 SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
341 SYM_DATA(efi_is64, .byte 1)
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.