[PATCH] x86-64: wakeup.S misc cleanups
o Various cleanups. One of the main purpose of cleanups is that make wakeup.S as close as possible to trampoline.S. o Following are the changes - Indentations for comments. - Changed the gdt table to compact form and to resemble the one in trampoline.S - Take the jump to 32bit from real mode using ljmpl. Makes code more readable. - After enabling long mode, directly take a long jump for 64bit mode. No need to take an extra jump to "reach_comaptibility_mode" - Stack is not used after real mode. So don't load stack in 32 bit mode. - No need to enable PGE here. - No need to do extra EFER read, anyway we trash the read contents. - No need to enable system call (EFER_SCE). Anyway it will be enabled when original EFER is restored. - No need to set MP, ET, NE, WP, AM bits in cr0. Very soon we will reload the original cr0 while restroing the processor state. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Vivek Goyal
Andi Kleen
parent
7db681d7e4
commit
275f55170e
@ -30,11 +30,12 @@ wakeup_code:
|
||||
cld
|
||||
# setup data segment
|
||||
movw %cs, %ax
|
||||
movw %ax, %ds # Make ds:0 point to wakeup_start
|
||||
movw %ax, %ds # Make ds:0 point to wakeup_start
|
||||
movw %ax, %ss
|
||||
mov $(wakeup_stack - wakeup_code), %sp # Private stack is needed for ASUS board
|
||||
# Private stack is needed for ASUS board
|
||||
mov $(wakeup_stack - wakeup_code), %sp
|
||||
|
||||
pushl $0 # Kill any dangerous flags
|
||||
pushl $0 # Kill any dangerous flags
|
||||
popfl
|
||||
|
||||
movl real_magic - wakeup_code, %eax
|
||||
@ -45,7 +46,7 @@ wakeup_code:
|
||||
jz 1f
|
||||
lcall $0xc000,$3
|
||||
movw %cs, %ax
|
||||
movw %ax, %ds # Bios might have played with that
|
||||
movw %ax, %ds # Bios might have played with that
|
||||
movw %ax, %ss
|
||||
1:
|
||||
|
||||
@ -75,9 +76,12 @@ wakeup_code:
|
||||
jmp 1f
|
||||
1:
|
||||
|
||||
.byte 0x66, 0xea # prefix + jmpi-opcode
|
||||
.long wakeup_32 - __START_KERNEL_map
|
||||
.word __KERNEL_CS
|
||||
ljmpl *(wakeup_32_vector - wakeup_code)
|
||||
|
||||
.balign 4
|
||||
wakeup_32_vector:
|
||||
.long wakeup_32 - __START_KERNEL_map
|
||||
.word __KERNEL32_CS, 0
|
||||
|
||||
.code32
|
||||
wakeup_32:
|
||||
@ -96,65 +100,50 @@ wakeup_32:
|
||||
jnc bogus_cpu
|
||||
movl %edx,%edi
|
||||
|
||||
movw $__KERNEL_DS, %ax
|
||||
movw %ax, %ds
|
||||
movw %ax, %es
|
||||
movw %ax, %fs
|
||||
movw %ax, %gs
|
||||
movl $__KERNEL_DS, %eax
|
||||
movl %eax, %ds
|
||||
|
||||
movw $__KERNEL_DS, %ax
|
||||
movw %ax, %ss
|
||||
|
||||
mov $(wakeup_stack - __START_KERNEL_map), %esp
|
||||
movl saved_magic - __START_KERNEL_map, %eax
|
||||
cmpl $0x9abcdef0, %eax
|
||||
jne bogus_32_magic
|
||||
|
||||
movw $0x0e00 + 'i', %ds:(0xb8012)
|
||||
movb $0xa8, %al ; outb %al, $0x80;
|
||||
|
||||
/*
|
||||
* Prepare for entering 64bits mode
|
||||
*/
|
||||
|
||||
/* Enable PAE mode and PGE */
|
||||
/* Enable PAE */
|
||||
xorl %eax, %eax
|
||||
btsl $5, %eax
|
||||
btsl $7, %eax
|
||||
movl %eax, %cr4
|
||||
|
||||
/* Setup early boot stage 4 level pagetables */
|
||||
movl $(wakeup_level4_pgt - __START_KERNEL_map), %eax
|
||||
movl %eax, %cr3
|
||||
|
||||
/* Setup EFER (Extended Feature Enable Register) */
|
||||
movl $MSR_EFER, %ecx
|
||||
rdmsr
|
||||
/* Fool rdmsr and reset %eax to avoid dependences */
|
||||
xorl %eax, %eax
|
||||
/* Enable Long Mode */
|
||||
xorl %eax, %eax
|
||||
btsl $_EFER_LME, %eax
|
||||
/* Enable System Call */
|
||||
btsl $_EFER_SCE, %eax
|
||||
|
||||
/* No Execute supported? */
|
||||
/* No Execute supported? */
|
||||
btl $20,%edi
|
||||
jnc 1f
|
||||
btsl $_EFER_NX, %eax
|
||||
1:
|
||||
|
||||
/* Make changes effective */
|
||||
1: movl $MSR_EFER, %ecx
|
||||
xorl %edx, %edx
|
||||
wrmsr
|
||||
wbinvd
|
||||
|
||||
xorl %eax, %eax
|
||||
btsl $31, %eax /* Enable paging and in turn activate Long Mode */
|
||||
btsl $0, %eax /* Enable protected mode */
|
||||
btsl $1, %eax /* Enable MP */
|
||||
btsl $4, %eax /* Enable ET */
|
||||
btsl $5, %eax /* Enable NE */
|
||||
btsl $16, %eax /* Enable WP */
|
||||
btsl $18, %eax /* Enable AM */
|
||||
|
||||
/* Make changes effective */
|
||||
movl %eax, %cr0
|
||||
|
||||
/* At this point:
|
||||
CR4.PAE must be 1
|
||||
CS.L must be 0
|
||||
@ -162,11 +151,6 @@ wakeup_32:
|
||||
Next instruction must be a branch
|
||||
This must be on identity-mapped page
|
||||
*/
|
||||
jmp reach_compatibility_mode
|
||||
reach_compatibility_mode:
|
||||
movw $0x0e00 + 'i', %ds:(0xb8012)
|
||||
movb $0xa8, %al ; outb %al, $0x80;
|
||||
|
||||
/*
|
||||
* At this point we're in long mode but in 32bit compatibility mode
|
||||
* with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
|
||||
@ -174,24 +158,19 @@ reach_compatibility_mode:
|
||||
* the new gdt/idt that has __KERNEL_CS with CS.L = 1.
|
||||
*/
|
||||
|
||||
movw $0x0e00 + 'n', %ds:(0xb8014)
|
||||
movb $0xa9, %al ; outb %al, $0x80
|
||||
|
||||
/* Load new GDT with the 64bit segment using 32bit descriptor */
|
||||
movl $(pGDT32 - __START_KERNEL_map), %eax
|
||||
lgdt (%eax)
|
||||
|
||||
movl $(wakeup_jumpvector - __START_KERNEL_map), %eax
|
||||
/* Finally jump in 64bit mode */
|
||||
ljmp *(%eax)
|
||||
ljmp *(wakeup_long64_vector - __START_KERNEL_map)
|
||||
|
||||
wakeup_jumpvector:
|
||||
.long wakeup_long64 - __START_KERNEL_map
|
||||
.word __KERNEL_CS
|
||||
.balign 4
|
||||
wakeup_long64_vector:
|
||||
.long wakeup_long64 - __START_KERNEL_map
|
||||
.word __KERNEL_CS, 0
|
||||
|
||||
.code64
|
||||
|
||||
/* Hooray, we are in Long 64-bit mode (but still running in low memory) */
|
||||
/* Hooray, we are in Long 64-bit mode (but still running in
|
||||
* low memory)
|
||||
*/
|
||||
wakeup_long64:
|
||||
/*
|
||||
* We must switch to a new descriptor in kernel space for the GDT
|
||||
@ -201,6 +180,9 @@ wakeup_long64:
|
||||
*/
|
||||
lgdt cpu_gdt_descr - __START_KERNEL_map
|
||||
|
||||
movw $0x0e00 + 'n', %ds:(0xb8014)
|
||||
movb $0xa9, %al ; outb %al, $0x80
|
||||
|
||||
movw $0x0e00 + 'u', %ds:(0xb8016)
|
||||
|
||||
nop
|
||||
@ -227,33 +209,19 @@ wakeup_long64:
|
||||
|
||||
.align 64
|
||||
gdta:
|
||||
/* Its good to keep gdt in sync with one in trampoline.S */
|
||||
.word 0, 0, 0, 0 # dummy
|
||||
|
||||
.word 0, 0, 0, 0 # unused
|
||||
|
||||
.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
|
||||
.word 0 # base address = 0
|
||||
.word 0x9B00 # code read/exec. ??? Why I need 0x9B00 (as opposed to 0x9A00 in order for this to work?)
|
||||
.word 0x00CF # granularity = 4096, 386
|
||||
# (+5th nibble of limit)
|
||||
|
||||
.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
|
||||
.word 0 # base address = 0
|
||||
.word 0x9200 # data read/write
|
||||
.word 0x00CF # granularity = 4096, 386
|
||||
# (+5th nibble of limit)
|
||||
# this is 64bit descriptor for code
|
||||
.word 0xFFFF
|
||||
.word 0
|
||||
.word 0x9A00 # code read/exec
|
||||
.word 0x00AF # as above, but it is long mode and with D=0
|
||||
/* ??? Why I need the accessed bit set in order for this to work? */
|
||||
.quad 0x00cf9b000000ffff # __KERNEL32_CS
|
||||
.quad 0x00af9b000000ffff # __KERNEL_CS
|
||||
.quad 0x00cf93000000ffff # __KERNEL_DS
|
||||
|
||||
idt_48a:
|
||||
.word 0 # idt limit = 0
|
||||
.word 0, 0 # idt base = 0L
|
||||
|
||||
gdt_48a:
|
||||
.word 0x8000 # gdt limit=2048,
|
||||
.word 0x800 # gdt limit=2048,
|
||||
# 256 GDT entries
|
||||
.word 0, 0 # gdt base (filled in later)
|
||||
|
||||
@ -263,7 +231,7 @@ video_mode: .quad 0
|
||||
video_flags: .quad 0
|
||||
|
||||
bogus_real_magic:
|
||||
movb $0xba,%al ; outb %al,$0x80
|
||||
movb $0xba,%al ; outb %al,$0x80
|
||||
jmp bogus_real_magic
|
||||
|
||||
bogus_32_magic:
|
||||
|
||||
Loading…
Reference in New Issue
Block a user