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I123 rename init #147

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9f66052
renaming .init with .bootlower
kraemmax Aug 21, 2020
6dea946
removed unused preprocessor macros
rottaran Oct 7, 2020
5e4e2ab
updated comment for init to bootlower change
rottaran Oct 7, 2020
1ee14ed
merge with master
rottaran Oct 7, 2020
f42cdf6
reverted accidential renaming of init section in user space
rottaran Oct 7, 2020
ce0961b
init segment vs sections cleanup
rottaran Oct 8, 2020
41e1362
Merge branch 'master' into i123-rename-init
rottaran Oct 8, 2020
b5233b9
added bsp trampoline for GDT setup back again
rottaran Oct 8, 2020
98c21de
removed typo, changed to .balign for consistency
rottaran Oct 8, 2020
6e11dfb
moved some code in start.S for IHK
Oct 13, 2020
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174 changes: 53 additions & 121 deletions kernel/boot/kernel-amd64-ihk/boot/start.S
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Original file line number Diff line number Diff line change
Expand Up @@ -31,8 +31,6 @@
.extern entry_bsp
.extern entry_ap

.section .bootlower, "awx" // the following code and data is in the low memory init section

// EFER bit 0: SYSCALL instruction enable
// EFER bit 8: IA-32e mode enable
// EFER bit 11: enable noexecute bit in page tables
Expand Down Expand Up @@ -64,135 +62,34 @@
#define CR4_MASK 0xFFFFFFFF
#define CR4_ENABLE 0x00000020

/** magic number for the Multiboot header. */
#define MULTIBOOT_HEADER_MAGIC 0x1BADB002
.section .rodata

/** multiboot flags towards the bootloader.
*
* https://www.gnu.org/software/grub/manual/multiboot/multiboot.html
* If bit 0 in the ‘flags’ word is set, then all boot modules loaded along with the operating system must be aligned on page (4KB) boundaries.
* If bit 1 in the ‘flags’ word is set, then information on available memory via at least the ‘mem_*’ fields of the Multiboot information structure must be included. If the boot loader is capable of passing a memory map (the ‘mmap_*’ fields) and one exists, then it may be included as well.
* If bit 2 in the ‘flags’ word is set, information about the video mode table must be available to the kernel.
* If bit 16 in the ‘flags’ word is set, then the fields at offsets 12-28 in the Multiboot header are valid, and the boot loader should use them instead of the fields in the actual executable header to calculate where to load the OS image. This information does not need to be provided if the kernel image is in elf format.
*/
#define MULTIBOOT_HEADER_FLAGS 0x00000000

.align 4
/** multiboot header: just magic, flags and checksum without the optional fields */
/*_mboot_header:
.long MULTIBOOT_HEADER_MAGIC
.long MULTIBOOT_HEADER_FLAGS
.long -(MULTIBOOT_HEADER_MAGIC+MULTIBOOT_HEADER_FLAGS)*/

/** Global Descriptor Table (GDT) during boot.
* see 3.4.5.1 Code- and Data-Segment Descriptor Types in Intel 253668-048US.
* granularity 0xa0 = 10100000b => limit granularity 4kb, operand size unset, 64bit mode
* access 0x9b = 10011011b => present, ring0, code/data, Execute/Read accessed
* 0011 read/write accessed
* 1001 execute only accessed
* 1011 execute/read accessed
* access 0xfb = 11111011 => present, ring3, code/data, Execute/Read accessed
* limit can be 0 because it is not used in 64bit mode
*/
.align 8
.global _boot_gdt_start
.balign 8
//.global _boot_gdt_start
_boot_gdt_start:
.quad 0x0000000000000000 // null descriptor
.quad 0x0000000000000000 // 0x08 unused
.quad 0x00a09b000000ffff // 0x10 kernel code
.quad 0x00a093000000ffff // 0x18 kernel data
.quad 0x0000000000000000 // null descriptor
.quad 0x0000000000000000 // 0x08 unused
.quad 0x00a09b000000ffff // 0x10 kernel code
.quad 0x00a093000000ffff // 0x18 kernel data
_boot_gdt_end:
.word 0 // padding to align ...
.word 0 // padding to align ...
_boot_gdt:
.word _boot_gdt_end - _boot_gdt_start - 1 // limit: length of the GDT
.quad _boot_gdt_start // base

/*.align 8
.global _mboot_table
_mboot_table: .quad 0
.global _mboot_magic
_mboot_magic: .quad 0*/

/* just for testing */
//.global _host_info_ptr
//_host_info_ptr: .quad 0

/* start code for the bootstrap processor BSP, i.e. the first core */
/*.code32
.align 8
.global _start_bsp
.type _start_bsp, @function
_start_bsp:
// eax and ebx contains the multiboot magic and table pointer,
// lets store this for later.
mov %eax, _mboot_magic
mov %ebx, _mboot_table

// activate the initial page table
mov $(EFER_MSR), %ecx // select the EFER MSR
rdmsr // read EFER
and $(EFER_MASK), %eax
or $(EFER_ENABLE), %eax
wrmsr // write EFER
mov %cr4, %edx
and $(CR4_MASK), %edx
or $(CR4_ENABLE), %edx
mov %edx, %cr4
mov $(BOOT_PML4-VIRT_ADDR), %edx // pointer to the Page Directory
mov %edx, %cr3
mov %cr0, %edx
and $(CR0_MASK), %edx
or $(CR0_ENABLE), %edx
mov %edx, %cr0 // switch to protected mode, with paging enabled and write protect

// load our own segment descriptor table
lgdt _boot_gdt
ljmp $0x10, $_start_bsp64 // switch CS to 64bit mode
*/
.code64
.align 8
.global _start_bsp64_pregdt
.type _start_bsp64_pregdt, @function
_start_bsp64_pregdt:
mov $(BOOT_STACK+BOOT_STACK_SIZE), %rsp // set up boot kernel stack
// load our own segment descriptor table, see above in this file
// the segments 0x10 and 0x18 match the final GDT of the kernel
lgdt _boot_gdt
// switch code segment to 0x10 instead of leftovers from the loader
// create a stack frame like from a far call and return
push $0x10 // KERNEL_CS
push $_start_bsp64
retfq
.word _boot_gdt_end - _boot_gdt_start - 1 // limit: length of the GDT
.quad _boot_gdt_start // base

_start_bsp64:
mov $0x18, %cx // kernel data selector
mov %cx, %ss
mov %cx, %ds
mov %cx, %es
mov %cx, %fs
mov %cx, %gs
cld // for gcc code

mov $(EFER_MSR), %ecx // select the EFER MSR
rdmsr // read EFER
and $(EFER_MASK), %eax
or $(EFER_ENABLE), %eax
wrmsr // write EFER
.section .text


// go to the stage 3 boot code, and never come back
xor %rbp, %rbp
pushq $0 // fake return address as first stack frame
jmp entry_bsp

.section .text

.code16
.align 8
.balign 8
.global _dbg_trampoline
base = .
_dbg_trampoline:

.align 8
.balign 8
jmp _dbg_trampoline_code

.org 8
Expand All @@ -206,7 +103,7 @@ _dbg_startap:
.quad 0x0

dbg_ljmp32: // overwritten in (II)
.long dbg_32prot - base
.long dbg_32prot - base
.word 0x20

boot_gdtptr:
Expand Down Expand Up @@ -267,13 +164,13 @@ test:

ljmpl *(dbg_ljmp32 - base)

.align 4
.balign 4
boot_idtptr:
.short 0
.long 0


.align 4
.balign 4
boot_gdt32:
.quad 0
.quad 0
Expand Down Expand Up @@ -349,9 +246,44 @@ dbg_loop:
.global _dbg_trampoline_end
_dbg_trampoline_end:

/** \f _start_bsp64_pregdt is called from ihk-entry.cc */
.code64
.balign 8
.global _start_bsp64_pregdt
.type _start_bsp64_pregdt, @function
_start_bsp64_pregdt:
mov $(BOOT_STACK+BOOT_STACK_SIZE), %rsp // set up boot kernel stack
// load our own segment descriptor table, see above in this file
// the segments 0x10 and 0x18 match the final GDT of the kernel
lgdt _boot_gdt
// switch code segment to 0x10 instead of leftovers from the loader
// create a stack frame like from a far call and return
push $0x10 // KERNEL_CS
push $_start_bsp64
retfq

_start_bsp64:
mov $0x18, %cx // kernel data selector
mov %cx, %ss
mov %cx, %ds
mov %cx, %es
mov %cx, %fs
mov %cx, %gs
cld // for gcc code

mov $(EFER_MSR), %ecx // select the EFER MSR
rdmsr // read EFER
and $(EFER_MASK), %eax
or $(EFER_ENABLE), %eax
wrmsr // write EFER

// go to the stage 3 boot code, and never come back
xor %rbp, %rbp
pushq $0 // fake return address as first stack frame
jmp entry_bsp

.code64
.align 8
.balign 8

.global _start_ap64_pregdt
.type _start_ap64_pregdt, @function
Expand Down
4 changes: 2 additions & 2 deletions kernel/boot/kernel-amd64-knc/boot/boot.ld
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Original file line number Diff line number Diff line change
Expand Up @@ -47,10 +47,10 @@ SECTIONS
{
/* LOAD_ADDR is begin of the init code and data */
/* load the boot code at VMA=LMA LOAD_ADDR */
.init LOAD_ADDR : AT(LOAD_ADDR)
.bootlower LOAD_ADDR : AT(LOAD_ADDR)
{
KEEP(*(.bootlower))
} : bootlower /* put into init segment */
} : init /* put into init segment */
PROVIDE (LOAD_END = .);

/* the begin of the upper half code and data in physical memory */
Expand Down
2 changes: 1 addition & 1 deletion kernel/boot/kernel-amd64-pc/boot/boot.ld
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ SECTIONS
.bootlower LOAD_ADDR : AT(LOAD_ADDR)
{
KEEP(*(.bootlower))
} : bootlower /* put into boot segment */
} : init /* put into init segment */
PROVIDE (LOAD_END = .);

/* the begin of the upper half code and data in physical memory */
Expand Down