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/* 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 linker script. */
.section .bss, "aw", @nobits
.global _stack
.global _estack
.global _stack_size
.align 16
_stack:
.space CONFIG_STACK_SIZE
_estack:
.set _stack_size, _estack - _stack
.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
xor %eax, %eax /* zero out the gs and fs segment index */
movl %eax, %fs
movl %eax, %gs /* Will be used for cpu_info */
#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 $(0xfffffff0), %esp
/*
* 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
.global per_cpu_segment_descriptors, per_cpu_segment_selector
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
per_cpu_segment_descriptors:
.rept CONFIG_MAX_CPUS
/* flat data segment */
.word 0xffff, 0x0000
#if ENV_X86_64
.byte 0x00, 0x92, 0xcf, 0x00
#else
.byte 0x00, 0x93, 0xcf, 0x00
#endif
.endr
gdt_end:
/* Segment selector pointing to the first per_cpu_segment_descriptor. */
per_cpu_segment_selector:
.long per_cpu_segment_descriptors - gdt
.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 instruction 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
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