330 lines
7.4 KiB
ArmAsm
330 lines
7.4 KiB
ArmAsm
/*
|
|
* linux/boot/head.S
|
|
*
|
|
* Copyright (C) 1991, 1992, 1993 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* head.S contains the 32-bit startup code.
|
|
*
|
|
* NOTE!!! Startup happens at absolute address 0x00001000, which is also where
|
|
* the page directory will exist. The startup code will be overwritten by
|
|
* the page directory. [According to comments etc elsewhere on a compressed
|
|
* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
|
|
*
|
|
* Page 0 is deliberately kept safe, since System Management Mode code in
|
|
* laptops may need to access the BIOS data stored there. This is also
|
|
* useful for future device drivers that either access the BIOS via VM86
|
|
* mode.
|
|
*/
|
|
|
|
/*
|
|
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
|
|
*/
|
|
.code32
|
|
.text
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/linkage.h>
|
|
#include <asm/segment.h>
|
|
#include <asm/pgtable_types.h>
|
|
#include <asm/page_types.h>
|
|
#include <asm/boot.h>
|
|
#include <asm/msr.h>
|
|
#include <asm/processor-flags.h>
|
|
#include <asm/asm-offsets.h>
|
|
|
|
__HEAD
|
|
.code32
|
|
ENTRY(startup_32)
|
|
cld
|
|
/*
|
|
* Test KEEP_SEGMENTS flag to see if the bootloader is asking
|
|
* us to not reload segments
|
|
*/
|
|
testb $(1<<6), BP_loadflags(%esi)
|
|
jnz 1f
|
|
|
|
cli
|
|
movl $(__KERNEL_DS), %eax
|
|
movl %eax, %ds
|
|
movl %eax, %es
|
|
movl %eax, %ss
|
|
1:
|
|
|
|
/*
|
|
* Calculate the delta between where we were compiled to run
|
|
* at and where we were actually loaded at. This can only be done
|
|
* with a short local call on x86. Nothing else will tell us what
|
|
* address we are running at. The reserved chunk of the real-mode
|
|
* data at 0x1e4 (defined as a scratch field) are used as the stack
|
|
* for this calculation. Only 4 bytes are needed.
|
|
*/
|
|
leal (BP_scratch+4)(%esi), %esp
|
|
call 1f
|
|
1: popl %ebp
|
|
subl $1b, %ebp
|
|
|
|
/* setup a stack and make sure cpu supports long mode. */
|
|
movl $boot_stack_end, %eax
|
|
addl %ebp, %eax
|
|
movl %eax, %esp
|
|
|
|
call verify_cpu
|
|
testl %eax, %eax
|
|
jnz no_longmode
|
|
|
|
/*
|
|
* Compute the delta between where we were compiled to run at
|
|
* and where the code will actually run at.
|
|
*
|
|
* %ebp contains the address we are loaded at by the boot loader and %ebx
|
|
* contains the address where we should move the kernel image temporarily
|
|
* for safe in-place decompression.
|
|
*/
|
|
|
|
#ifdef CONFIG_RELOCATABLE
|
|
movl %ebp, %ebx
|
|
movl BP_kernel_alignment(%esi), %eax
|
|
decl %eax
|
|
addl %eax, %ebx
|
|
notl %eax
|
|
andl %eax, %ebx
|
|
#else
|
|
movl $LOAD_PHYSICAL_ADDR, %ebx
|
|
#endif
|
|
|
|
/* Target address to relocate to for decompression */
|
|
addl $z_extract_offset, %ebx
|
|
|
|
/*
|
|
* Prepare for entering 64 bit mode
|
|
*/
|
|
|
|
/* Load new GDT with the 64bit segments using 32bit descriptor */
|
|
leal gdt(%ebp), %eax
|
|
movl %eax, gdt+2(%ebp)
|
|
lgdt gdt(%ebp)
|
|
|
|
/* Enable PAE mode */
|
|
xorl %eax, %eax
|
|
orl $(X86_CR4_PAE), %eax
|
|
movl %eax, %cr4
|
|
|
|
/*
|
|
* Build early 4G boot pagetable
|
|
*/
|
|
/* Initialize Page tables to 0 */
|
|
leal pgtable(%ebx), %edi
|
|
xorl %eax, %eax
|
|
movl $((4096*6)/4), %ecx
|
|
rep stosl
|
|
|
|
/* Build Level 4 */
|
|
leal pgtable + 0(%ebx), %edi
|
|
leal 0x1007 (%edi), %eax
|
|
movl %eax, 0(%edi)
|
|
|
|
/* Build Level 3 */
|
|
leal pgtable + 0x1000(%ebx), %edi
|
|
leal 0x1007(%edi), %eax
|
|
movl $4, %ecx
|
|
1: movl %eax, 0x00(%edi)
|
|
addl $0x00001000, %eax
|
|
addl $8, %edi
|
|
decl %ecx
|
|
jnz 1b
|
|
|
|
/* Build Level 2 */
|
|
leal pgtable + 0x2000(%ebx), %edi
|
|
movl $0x00000183, %eax
|
|
movl $2048, %ecx
|
|
1: movl %eax, 0(%edi)
|
|
addl $0x00200000, %eax
|
|
addl $8, %edi
|
|
decl %ecx
|
|
jnz 1b
|
|
|
|
/* Enable the boot page tables */
|
|
leal pgtable(%ebx), %eax
|
|
movl %eax, %cr3
|
|
|
|
/* Enable Long mode in EFER (Extended Feature Enable Register) */
|
|
movl $MSR_EFER, %ecx
|
|
rdmsr
|
|
btsl $_EFER_LME, %eax
|
|
wrmsr
|
|
|
|
/*
|
|
* Setup for the jump to 64bit mode
|
|
*
|
|
* When the jump is performend we will be in long mode but
|
|
* in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1
|
|
* (and in turn EFER.LMA = 1). To jump into 64bit mode we use
|
|
* the new gdt/idt that has __KERNEL_CS with CS.L = 1.
|
|
* We place all of the values on our mini stack so lret can
|
|
* used to perform that far jump.
|
|
*/
|
|
pushl $__KERNEL_CS
|
|
leal startup_64(%ebp), %eax
|
|
pushl %eax
|
|
|
|
/* Enter paged protected Mode, activating Long Mode */
|
|
movl $(X86_CR0_PG | X86_CR0_PE), %eax /* Enable Paging and Protected mode */
|
|
movl %eax, %cr0
|
|
|
|
/* Jump from 32bit compatibility mode into 64bit mode. */
|
|
lret
|
|
ENDPROC(startup_32)
|
|
|
|
no_longmode:
|
|
/* This isn't an x86-64 CPU so hang */
|
|
1:
|
|
hlt
|
|
jmp 1b
|
|
|
|
#include "../../kernel/verify_cpu_64.S"
|
|
|
|
/*
|
|
* Be careful here startup_64 needs to be at a predictable
|
|
* address so I can export it in an ELF header. Bootloaders
|
|
* should look at the ELF header to find this address, as
|
|
* it may change in the future.
|
|
*/
|
|
.code64
|
|
.org 0x200
|
|
ENTRY(startup_64)
|
|
/*
|
|
* We come here either from startup_32 or directly from a
|
|
* 64bit bootloader. If we come here from a bootloader we depend on
|
|
* an identity mapped page table being provied that maps our
|
|
* entire text+data+bss and hopefully all of memory.
|
|
*/
|
|
|
|
/* Setup data segments. */
|
|
xorl %eax, %eax
|
|
movl %eax, %ds
|
|
movl %eax, %es
|
|
movl %eax, %ss
|
|
movl %eax, %fs
|
|
movl %eax, %gs
|
|
lldt %ax
|
|
movl $0x20, %eax
|
|
ltr %ax
|
|
|
|
/*
|
|
* Compute the decompressed kernel start address. It is where
|
|
* we were loaded at aligned to a 2M boundary. %rbp contains the
|
|
* decompressed kernel start address.
|
|
*
|
|
* If it is a relocatable kernel then decompress and run the kernel
|
|
* from load address aligned to 2MB addr, otherwise decompress and
|
|
* run the kernel from LOAD_PHYSICAL_ADDR
|
|
*
|
|
* We cannot rely on the calculation done in 32-bit mode, since we
|
|
* may have been invoked via the 64-bit entry point.
|
|
*/
|
|
|
|
/* Start with the delta to where the kernel will run at. */
|
|
#ifdef CONFIG_RELOCATABLE
|
|
leaq startup_32(%rip) /* - $startup_32 */, %rbp
|
|
movl BP_kernel_alignment(%rsi), %eax
|
|
decl %eax
|
|
addq %rax, %rbp
|
|
notq %rax
|
|
andq %rax, %rbp
|
|
#else
|
|
movq $LOAD_PHYSICAL_ADDR, %rbp
|
|
#endif
|
|
|
|
/* Target address to relocate to for decompression */
|
|
leaq z_extract_offset(%rbp), %rbx
|
|
|
|
/* Set up the stack */
|
|
leaq boot_stack_end(%rbx), %rsp
|
|
|
|
/* Zero EFLAGS */
|
|
pushq $0
|
|
popfq
|
|
|
|
/*
|
|
* Copy the compressed kernel to the end of our buffer
|
|
* where decompression in place becomes safe.
|
|
*/
|
|
pushq %rsi
|
|
leaq (_bss-8)(%rip), %rsi
|
|
leaq (_bss-8)(%rbx), %rdi
|
|
movq $_bss /* - $startup_32 */, %rcx
|
|
shrq $3, %rcx
|
|
std
|
|
rep movsq
|
|
cld
|
|
popq %rsi
|
|
|
|
/*
|
|
* Jump to the relocated address.
|
|
*/
|
|
leaq relocated(%rbx), %rax
|
|
jmp *%rax
|
|
|
|
.text
|
|
relocated:
|
|
|
|
/*
|
|
* Clear BSS (stack is currently empty)
|
|
*/
|
|
xorl %eax, %eax
|
|
leaq _bss(%rip), %rdi
|
|
leaq _ebss(%rip), %rcx
|
|
subq %rdi, %rcx
|
|
shrq $3, %rcx
|
|
rep stosq
|
|
|
|
/*
|
|
* Do the decompression, and jump to the new kernel..
|
|
*/
|
|
pushq %rsi /* Save the real mode argument */
|
|
movq %rsi, %rdi /* real mode address */
|
|
leaq boot_heap(%rip), %rsi /* malloc area for uncompression */
|
|
leaq input_data(%rip), %rdx /* input_data */
|
|
movl $z_input_len, %ecx /* input_len */
|
|
movq %rbp, %r8 /* output target address */
|
|
call decompress_kernel
|
|
popq %rsi
|
|
|
|
/*
|
|
* Jump to the decompressed kernel.
|
|
*/
|
|
jmp *%rbp
|
|
|
|
.data
|
|
gdt:
|
|
.word gdt_end - gdt
|
|
.long gdt
|
|
.word 0
|
|
.quad 0x0000000000000000 /* NULL descriptor */
|
|
.quad 0x00af9a000000ffff /* __KERNEL_CS */
|
|
.quad 0x00cf92000000ffff /* __KERNEL_DS */
|
|
.quad 0x0080890000000000 /* TS descriptor */
|
|
.quad 0x0000000000000000 /* TS continued */
|
|
gdt_end:
|
|
|
|
/*
|
|
* Stack and heap for uncompression
|
|
*/
|
|
.bss
|
|
.balign 4
|
|
boot_heap:
|
|
.fill BOOT_HEAP_SIZE, 1, 0
|
|
boot_stack:
|
|
.fill BOOT_STACK_SIZE, 1, 0
|
|
boot_stack_end:
|
|
|
|
/*
|
|
* Space for page tables (not in .bss so not zeroed)
|
|
*/
|
|
.section ".pgtable","a",@nobits
|
|
.balign 4096
|
|
pgtable:
|
|
.fill 6*4096, 1, 0
|