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
|
/* SPDX-License-Identifier: GPL-2.0-only */
#include <cpu/x86/post_code.h>
#include <arch/ram_segs.h>
/* Place the stack in the bss section. It's not necessary to define it in the
* the linker script. */
.section .bss, "aw", @nobits
.global _stack
.global _estack
.global _stack_size
/* Stack alignment is not enforced with rmodule loader, reserve one
* extra CPU such that alignment can be enforced on entry. */
.align CONFIG_STACK_SIZE
_stack:
.space (CONFIG_MAX_CPUS+1)*CONFIG_STACK_SIZE
_estack:
.set _stack_size, _estack - _stack
#if CONFIG(COOP_MULTITASKING)
.global thread_stacks
thread_stacks:
.space CONFIG_STACK_SIZE*CONFIG_NUM_THREADS
#endif
.section ".text._start", "ax", @progbits
#if ENV_X86_64
.code64
#else
.code32
#endif
.globl _start
_start:
cli
#if ENV_X86_64
movabs $gdtaddr, %rax
lgdt (%rax)
#else
lgdt %cs:gdtaddr
ljmp $RAM_CODE_SEG, $1f
#endif
1: movl $RAM_DATA_SEG, %eax
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
movl %eax, %fs
movl %eax, %gs
#if ENV_X86_64
mov $RAM_CODE_SEG64, %ecx
call SetCodeSelector
#endif
post_code(POST_ENTRY_C_START) /* post 13 */
cld
#if ENV_X86_64
mov %rdi, %rax
movabs %rax, _cbmem_top_ptr
movabs $_stack, %rdi
#else
/* The return argument is at 0(%esp), the calling argument at 4(%esp) */
movl 4(%esp), %eax
movl %eax, _cbmem_top_ptr
leal _stack, %edi
#endif
/** poison the stack. Code should not count on the
* stack being full of zeros. This stack poisoning
* recently uncovered a bug in the broadcast SIPI
* code.
*/
movl $_estack, %ecx
subl %edi, %ecx
shrl $2, %ecx /* it is 32 bit aligned, right? */
movl $0xDEADBEEF, %eax
rep
stosl
/* Set new stack with enforced alignment. */
movl $_estack, %esp
andl $(~(CONFIG_STACK_SIZE-1)), %esp
#if CONFIG(COOP_MULTITASKING)
/* Push the thread pointer. */
push $0
#endif
/* Push the CPU index and struct CPU */
push $0
push $0
/*
* Now we are finished. Memory is up, data is copied and
* bss is cleared. Now we call the main routine and
* let it do the rest.
*/
post_code(POST_PRE_HARDWAREMAIN) /* post 6e */
andl $0xFFFFFFF0, %esp
#if CONFIG(ASAN_IN_RAMSTAGE)
call asan_init
#endif
#if CONFIG(GDB_WAIT)
call gdb_hw_init
call gdb_stub_breakpoint
#endif
call main
/* NOTREACHED */
.Lhlt:
post_code(POST_DEAD_CODE) /* post ee */
hlt
jmp .Lhlt
#if CONFIG(GDB_WAIT)
.globl gdb_stub_breakpoint
gdb_stub_breakpoint:
#if ENV_X86_64
pop %rax /* Return address */
pushfl
push %cs
push %rax /* Return address */
push $0 /* No error code */
push $32 /* vector 32 is user defined */
#else
popl %eax /* Return address */
pushfl
pushl %cs
pushl %eax /* Return address */
pushl $0 /* No error code */
pushl $32 /* vector 32 is user defined */
#endif
jmp int_hand
#endif
.globl gdt, gdt_end
gdtaddr:
.word gdt_end - gdt - 1
#if ENV_X86_64
.quad gdt
#else
.long gdt /* we know the offset */
#endif
.data
/* This is the gdt for GCC part of coreboot.
* It is different from the gdt in ASM part of coreboot
* which is defined in gdt_init.S
*
* When the machine is initially started, we use a very simple
* gdt from ROM (that in gdt_init.S) which only contains those
* entries we need for protected mode.
*
* When we're executing code from RAM, we want to do more complex
* stuff, like initializing PCI option ROMs in real mode, or doing
* a resume from a suspend to RAM.
*/
gdt:
/* selgdt 0, unused */
.word 0x0000, 0x0000 /* dummy */
.byte 0x00, 0x00, 0x00, 0x00
/* selgdt 8, unused */
.word 0x0000, 0x0000 /* dummy */
.byte 0x00, 0x00, 0x00, 0x00
/* selgdt 0x10, flat code segment */
.word 0xffff, 0x0000
.byte 0x00, 0x9b, 0xcf, 0x00 /* G=1 and 0x0f, So we get 4Gbytes for
* limit
*/
/* selgdt 0x18, flat data segment */
.word 0xffff, 0x0000
#if ENV_X86_64
.byte 0x00, 0x92, 0xcf, 0x00
#else
.byte 0x00, 0x93, 0xcf, 0x00
#endif
/* selgdt 0x20, unused */
.word 0x0000, 0x0000 /* dummy */
.byte 0x00, 0x00, 0x00, 0x00
/* The next two entries are used for executing VGA option ROMs */
/* selgdt 0x28 16 bit 64k code at 0x00000000 */
.word 0xffff, 0x0000
.byte 0, 0x9a, 0, 0
/* selgdt 0x30 16 bit 64k data at 0x00000000 */
.word 0xffff, 0x0000
.byte 0, 0x92, 0, 0
/* The next two entries are used for ACPI S3 RESUME */
/* selgdt 0x38, flat data segment 16 bit */
.word 0x0000, 0x0000 /* dummy */
.byte 0x00, 0x93, 0x8f, 0x00 /* G=1 and 0x0f, So we get 4Gbytes for
* limit
*/
/* selgdt 0x40, flat code segment 16 bit */
.word 0xffff, 0x0000
.byte 0x00, 0x9b, 0x8f, 0x00 /* G=1 and 0x0f, So we get 4Gbytes for
* limit
*/
#if ENV_X86_64
/* selgdt 0x48, flat x64 code segment */
.word 0xffff, 0x0000
.byte 0x00, 0x9b, 0xaf, 0x00
#endif
gdt_end:
.section ".text._start", "ax", @progbits
#if ENV_X86_64
SetCodeSelector:
# save rsp because iret will align it to a 16 byte boundary
mov %rsp, %rdx
# use iret to jump to a 64-bit offset in a new code segment
# iret will pop cs:rip, flags, then ss:rsp
mov %ss, %ax # need to push ss..
push %rax # push ss instuction not valid in x64 mode,
# so use ax
push %rsp
pushfq
push %rcx # cx is code segment selector from caller
movabs $setCodeSelectorLongJump, %rax
push %rax
# the iret will continue at next instruction, with the new cs value
# loaded
iretq
setCodeSelectorLongJump:
# restore rsp, it might not have been 16-byte aligned on entry
mov %rdx, %rsp
ret
#endif
|
