1 files changed, 166 insertions, 0 deletions

diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/kernel/trampoline_64.S
new file mode 100644
index 000000000000..607983b0d27b
--- /dev/null
+++ b/arch/x86/kernel/trampoline_64.S
@@ -0,0 +1,166 @@
+/*
+ *
+ *      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 
+ *      trampoline page to make our stack and everything else
+ *      is a mystery.
+ *
+ *      In fact we don't actually need a stack so we don't
+ *      set one up.
+ *
+ *      On entry to trampoline_data, the processor is in real mode
+ *      with 16-bit addressing and 16-bit data.  CS has some value
+ *      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.
+ */
+
+#include <linux/linkage.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/msr.h>
+#include <asm/segment.h>
+
+.data
+
+.code16
+
+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
+
+
+        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
+        testl   %eax, %eax              # Check for return code
+        jnz     no_longmode
+
+        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
+         * operand size is 16bit. Use lgdtl instead to force operand size
+         * to 32 bit.
+         */
+
+        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
+
+        # 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
+no_longmode:
+        hlt
+        jmp no_longmode
+#include "verify_cpu_64.S"
+
+        # Careful these need to be in the same 64K segment as the above;
+tidt:
+        .word   0                       # idt limit = 0
+        .word   0, 0                    # idt base = 0L
+
+        # 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
+
+ENTRY(trampoline_end)