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#include <xen/config.h>
#include <hypervisor-ifs/hypervisor-if.h>
#include <asm/page.h>
#define SECONDARY_CPU_FLAG 0xA5A5A5A5
.text
ENTRY(start)
jmp __start
.align 4
/*** MULTIBOOT HEADER ****/
/* Magic number indicating a Multiboot header. */
.long 0x1BADB002
/* Flags to bootloader (see Multiboot spec). */
.long 0x00000002
/* Checksum: must be the negated sum of the first two fields. */
.long -0x1BADB004
bad_cpu_msg:
.asciz "ERR: Not a P6-compatible CPU!"
not_multiboot_msg:
.asciz "ERR: Not a Multiboot bootloader!"
bad_cpu:
mov $SYMBOL_NAME(bad_cpu_msg)-__PAGE_OFFSET,%esi
jmp print_err
not_multiboot:
mov $SYMBOL_NAME(not_multiboot_msg)-__PAGE_OFFSET,%esi
print_err:
mov $0xB8000,%edi # VGA framebuffer
1: mov (%esi),%bl
test %bl,%bl # Terminate on '\0' sentinel
2: je 2b
mov $0x3f8+5,%dx # UART Line Status Register
3: in %dx,%al
test $0x20,%al # Test THR Empty flag
je 3b
mov $0x3f8+0,%dx # UART Transmit Holding Register
mov %bl,%al
out %al,%dx # Send a character over the serial line
movsb # Write a character to the VGA framebuffer
mov $7,%al
stosb # Write an attribute to the VGA framebuffer
jmp 1b
__start:
/* Set up a few descriptors: on entry only CS is guaranteed good. */
lgdt %cs:nopaging_gdt_descr-__PAGE_OFFSET
mov $(__HYPERVISOR_DS),%ecx
mov %ecx,%ds
mov %ecx,%es
mov %ecx,%fs
mov %ecx,%gs
ljmp $(__HYPERVISOR_CS),$(1f)-__PAGE_OFFSET
1: lss stack_start-__PAGE_OFFSET,%esp
/* Reset EFLAGS (subsumes CLI and CLD). */
pushl $0
popf
/* CPU type checks. We need P6+. */
mov $0x200000,%edx
pushfl
pop %ecx
and %edx,%ecx
jne bad_cpu # ID bit should be clear
pushl %edx
popfl
pushfl
pop %ecx
and %edx,%ecx
je bad_cpu # ID bit should be set
/* Set up FPU. */
fninit
/* Set up CR4, except global flag which Intel requires should be */
/* left until after paging is enabled (IA32 Manual Vol. 3, Sec. 2.5) */
mov mmu_cr4_features-__PAGE_OFFSET,%ecx
and $0x7f,%cl # CR4.PGE (global enable)
mov %ecx,%cr4
cmp $(SECONDARY_CPU_FLAG),%ebx
je start_paging
/* Check for Multiboot bootloader */
cmp $0x2BADB002,%eax
jne not_multiboot
/* Save the Multiboot info structure for later use. */
add $__PAGE_OFFSET,%ebx
push %ebx
/* Initialize BSS (no nasty surprises!) */
mov $__bss_start-__PAGE_OFFSET,%edi
mov $_end-__PAGE_OFFSET,%ecx
sub %edi,%ecx
xor %eax,%eax
rep stosb
/* Initialize low and high mappings of all memory with 4MB pages */
mov $idle_pg_table-__PAGE_OFFSET,%edi
mov $0x1e3,%eax /* PRESENT+RW+A+D+4MB+GLOBAL */
1: mov %eax,__PAGE_OFFSET>>20(%edi) /* high mapping */
stosl /* low mapping */
add $(1<<L2_PAGETABLE_SHIFT),%eax
cmp $DIRECTMAP_PHYS_END+0x1e3,%eax
jne 1b
1: stosl /* low mappings cover as much physmem as possible */
add $(1<<L2_PAGETABLE_SHIFT),%eax
cmp $__HYPERVISOR_VIRT_START+0x1e3,%eax
jne 1b
/* Initialise IDT with simple error defaults. */
lea ignore_int,%edx
mov $(__HYPERVISOR_CS << 16),%eax
mov %dx,%ax /* selector = 0x0010 = cs */
mov $0x8E00,%dx /* interrupt gate - dpl=0, present */
lea SYMBOL_NAME(idt_table)-__PAGE_OFFSET,%edi
mov $256,%ecx
1: mov %eax,(%edi)
mov %edx,4(%edi)
add $8,%edi
loop 1b
start_paging:
mov $idle_pg_table-__PAGE_OFFSET,%eax
mov %eax,%cr3
mov $0x80050033,%eax /* hi-to-lo: PG,AM,WP,NE,ET,MP,PE */
mov %eax,%cr0
jmp 1f
1: /* Install relocated selectors (FS/GS unused). */
lgdt gdt_descr
mov $(__HYPERVISOR_DS),%ecx
mov %ecx,%ds
mov %ecx,%es
mov %ecx,%ss
ljmp $(__HYPERVISOR_CS),$1f
1: /* Paging enabled, so we can now enable GLOBAL mappings in CR4. */
mov mmu_cr4_features,%ecx
mov %ecx,%cr4
/* Relocate ESP */
add $__PAGE_OFFSET,%esp
lidt idt_descr
cmp $(SECONDARY_CPU_FLAG),%ebx
je start_secondary
/* Call into main C routine. This should never return.*/
call cmain
ud2 /* Force a panic (invalid opcode). */
/* This is the default interrupt handler. */
int_msg:
.asciz "Unknown interrupt\n"
ALIGN
ignore_int:
cld
mov $(__HYPERVISOR_DS),%eax
mov %eax,%ds
mov %eax,%es
pushl $int_msg
call SYMBOL_NAME(printf)
1: jmp 1b
/*** STACK LOCATION ***/
ENTRY(stack_start)
.long SYMBOL_NAME(cpu0_stack) + 8100 - __PAGE_OFFSET
.long __HYPERVISOR_DS
/*** DESCRIPTOR TABLES ***/
.globl SYMBOL_NAME(idt)
.globl SYMBOL_NAME(gdt)
ALIGN
.word 0
idt_descr:
.word 256*8-1
SYMBOL_NAME(idt):
.long SYMBOL_NAME(idt_table)
.word 0
gdt_descr:
.word (LAST_RESERVED_GDT_ENTRY*8)+7
SYMBOL_NAME(gdt):
.long SYMBOL_NAME(gdt_table) /* gdt base */
.word 0
nopaging_gdt_descr:
.word (LAST_RESERVED_GDT_ENTRY*8)+7
.long SYMBOL_NAME(gdt_table)-__PAGE_OFFSET
ALIGN
/* NB. Rings != 0 get access up to 0xFC400000. This allows access to the */
/* machine->physical mapping table. Ring 0 can access all memory. */
ENTRY(gdt_table)
.fill FIRST_RESERVED_GDT_ENTRY,8,0
.quad 0x0000000000000000 /* unused */
.quad 0x00cf9a000000ffff /* 0x0808 ring 0 4.00GB code at 0x0 */
.quad 0x00cf92000000ffff /* 0x0810 ring 0 4.00GB data at 0x0 */
.quad 0x00cfba000000c3ff /* 0x0819 ring 1 3.95GB code at 0x0 */
.quad 0x00cfb2000000c3ff /* 0x0821 ring 1 3.95GB data at 0x0 */
.quad 0x00cffa000000c3ff /* 0x082b ring 3 3.95GB code at 0x0 */
.quad 0x00cff2000000c3ff /* 0x0833 ring 3 3.95GB data at 0x0 */
.quad 0x0000000000000000 /* unused */
.fill 2*NR_CPUS,8,0 /* space for TSS and LDT per CPU */
.org 0x1000
ENTRY(idle_pg_table) # Initial page directory is 4kB
.org 0x2000
ENTRY(cpu0_stack) # Initial stack is 8kB
.org 0x4000
ENTRY(stext)
ENTRY(_stext)
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