* Trampoline.S Derived from Setup.S by Linus Torvalds
*
* 4 Jan 1997 Michael Chastain: changed to gnu as.
+ * 15 Sept 2005 Eric Biederman: 64bit PIC support
*
* Entry: CS:IP point to the start of our code, we are
* in real mode with no stack, but the rest of the
* and IP is zero. Thus, data addresses need to be absolute
* (no relocation) and are taken with regard to r_base.
*
+ * With the addition of trampoline_level4_pgt this code can
+ * now enter a 64bit kernel that lives at arbitrary 64bit
+ * physical addresses.
+ *
* If you work on this file, check the object module with objdump
* --full-contents --reloc to make sure there are no relocation
- * entries. For the GDT entry we do hand relocation in smpboot.c
- * because of 64bit linker limitations.
+ * entries.
*/
#include <linux/linkage.h>
-#include <asm/segment.h>
+#include <asm/pgtable.h>
#include <asm/page.h>
+#include <asm/msr.h>
+#include <asm/segment.h>
.data
ENTRY(trampoline_data)
r_base = .
+ cli # We should be safe anyway
wbinvd
mov %cs, %ax # Code and data in the same place
mov %ax, %ds
+ mov %ax, %es
+ mov %ax, %ss
- cli # We should be safe anyway
movl $0xA5A5A5A5, trampoline_data - r_base
# write marker for master knows we're running
+ # Setup stack
+ movw $(trampoline_stack_end - r_base), %sp
+
+ call verify_cpu # Verify the cpu supports long mode
+
+ mov %cs, %ax
+ movzx %ax, %esi # Find the 32bit trampoline location
+ shll $4, %esi
+
+ # Fixup the vectors
+ addl %esi, startup_32_vector - r_base
+ addl %esi, startup_64_vector - r_base
+ addl %esi, tgdt + 2 - r_base # Fixup the gdt pointer
+
/*
* GDT tables in non default location kernel can be beyond 16MB and
* lgdt will not be able to load the address as in real mode default
* to 32 bit.
*/
- lidtl idt_48 - r_base # load idt with 0, 0
- lgdtl gdt_48 - r_base # load gdt with whatever is appropriate
+ lidtl tidt - r_base # load idt with 0, 0
+ lgdtl tgdt - r_base # load gdt with whatever is appropriate
xor %ax, %ax
inc %ax # protected mode (PE) bit
lmsw %ax # into protected mode
- # flaush prefetch and jump to startup_32 in arch/x86_64/kernel/head.S
- ljmpl $__KERNEL32_CS, $(startup_32-__START_KERNEL_map)
+
+ # flush prefetch and jump to startup_32
+ ljmpl *(startup_32_vector - r_base)
+
+ .code32
+ .balign 4
+startup_32:
+ movl $__KERNEL_DS, %eax # Initialize the %ds segment register
+ movl %eax, %ds
+
+ xorl %eax, %eax
+ btsl $5, %eax # Enable PAE mode
+ movl %eax, %cr4
+
+ # Setup trampoline 4 level pagetables
+ leal (trampoline_level4_pgt - r_base)(%esi), %eax
+ movl %eax, %cr3
+
+ movl $MSR_EFER, %ecx
+ movl $(1 << _EFER_LME), %eax # Enable Long Mode
+ xorl %edx, %edx
+ wrmsr
+
+ xorl %eax, %eax
+ btsl $31, %eax # Enable paging and in turn activate Long Mode
+ btsl $0, %eax # Enable protected mode
+ movl %eax, %cr0
+
+ /*
+ * 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
+ * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use
+ * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
+ */
+ ljmp *(startup_64_vector - r_base)(%esi)
+
+ .code64
+ .balign 4
+startup_64:
+ # Now jump into the kernel using virtual addresses
+ movq $secondary_startup_64, %rax
+ jmp *%rax
+
+ .code16
+verify_cpu:
+ pushl $0 # Kill any dangerous flags
+ popfl
+
+ /* minimum CPUID flags for x86-64 */
+ /* see http://www.x86-64.org/lists/discuss/msg02971.html */
+#define REQUIRED_MASK1 ((1<<0)|(1<<3)|(1<<4)|(1<<5)|(1<<6)|(1<<8)|\
+ (1<<13)|(1<<15)|(1<<24)|(1<<25)|(1<<26))
+#define REQUIRED_MASK2 (1<<29)
+
+ pushfl # check for cpuid
+ popl %eax
+ movl %eax, %ebx
+ xorl $0x200000,%eax
+ pushl %eax
+ popfl
+ pushfl
+ popl %eax
+ pushl %ebx
+ popfl
+ cmpl %eax, %ebx
+ jz no_longmode
+
+ xorl %eax, %eax # See if cpuid 1 is implemented
+ cpuid
+ cmpl $0x1, %eax
+ jb no_longmode
+
+ movl $0x01, %eax # Does the cpu have what it takes?
+ cpuid
+ andl $REQUIRED_MASK1, %edx
+ xorl $REQUIRED_MASK1, %edx
+ jnz no_longmode
+
+ movl $0x80000000, %eax # See if extended cpuid is implemented
+ cpuid
+ cmpl $0x80000001, %eax
+ jb no_longmode
+
+ movl $0x80000001, %eax # Does the cpu have what it takes?
+ cpuid
+ andl $REQUIRED_MASK2, %edx
+ xorl $REQUIRED_MASK2, %edx
+ jnz no_longmode
+
+ ret # The cpu supports long mode
+
+no_longmode:
+ hlt
+ jmp no_longmode
+
# Careful these need to be in the same 64K segment as the above;
-idt_48:
+tidt:
.word 0 # idt limit = 0
.word 0, 0 # idt base = 0L
-gdt_48:
- .short GDT_ENTRIES*8 - 1 # gdt limit
- .long cpu_gdt_table-__START_KERNEL_map
+ # Duplicate the global descriptor table
+ # so the kernel can live anywhere
+ .balign 4
+tgdt:
+ .short tgdt_end - tgdt # gdt limit
+ .long tgdt - r_base
+ .short 0
+ .quad 0x00cf9b000000ffff # __KERNEL32_CS
+ .quad 0x00af9b000000ffff # __KERNEL_CS
+ .quad 0x00cf93000000ffff # __KERNEL_DS
+tgdt_end:
+
+ .balign 4
+startup_32_vector:
+ .long startup_32 - r_base
+ .word __KERNEL32_CS, 0
+
+ .balign 4
+startup_64_vector:
+ .long startup_64 - r_base
+ .word __KERNEL_CS, 0
+
+trampoline_stack:
+ .org 0x1000
+trampoline_stack_end:
+ENTRY(trampoline_level4_pgt)
+ .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+ .fill 510,8,0
+ .quad level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
-.globl trampoline_end
-trampoline_end:
+ENTRY(trampoline_end)
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