Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * |
| 3 | * Trampoline.S Derived from Setup.S by Linus Torvalds |
| 4 | * |
| 5 | * 4 Jan 1997 Michael Chastain: changed to gnu as. |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 6 | * 15 Sept 2005 Eric Biederman: 64bit PIC support |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | * |
| 8 | * Entry: CS:IP point to the start of our code, we are |
| 9 | * in real mode with no stack, but the rest of the |
| 10 | * trampoline page to make our stack and everything else |
| 11 | * is a mystery. |
| 12 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | * On entry to trampoline_data, the processor is in real mode |
| 14 | * with 16-bit addressing and 16-bit data. CS has some value |
| 15 | * and IP is zero. Thus, data addresses need to be absolute |
| 16 | * (no relocation) and are taken with regard to r_base. |
| 17 | * |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 18 | * With the addition of trampoline_level4_pgt this code can |
| 19 | * now enter a 64bit kernel that lives at arbitrary 64bit |
| 20 | * physical addresses. |
| 21 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 22 | * If you work on this file, check the object module with objdump |
| 23 | * --full-contents --reloc to make sure there are no relocation |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 24 | * entries. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | */ |
| 26 | |
| 27 | #include <linux/linkage.h> |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 28 | #include <asm/pgtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <asm/page.h> |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 30 | #include <asm/msr.h> |
| 31 | #include <asm/segment.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | |
Jan Beulich | 121d7bf | 2007-10-17 18:04:37 +0200 | [diff] [blame] | 33 | .section .rodata, "a", @progbits |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | |
| 35 | .code16 |
| 36 | |
| 37 | ENTRY(trampoline_data) |
| 38 | r_base = . |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 39 | cli # We should be safe anyway |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | wbinvd |
| 41 | mov %cs, %ax # Code and data in the same place |
| 42 | mov %ax, %ds |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 43 | mov %ax, %es |
| 44 | mov %ax, %ss |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | |
| 47 | movl $0xA5A5A5A5, trampoline_data - r_base |
| 48 | # write marker for master knows we're running |
| 49 | |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 50 | # Setup stack |
| 51 | movw $(trampoline_stack_end - r_base), %sp |
| 52 | |
| 53 | call verify_cpu # Verify the cpu supports long mode |
Vivek Goyal | a4831e0 | 2007-05-02 19:27:08 +0200 | [diff] [blame] | 54 | testl %eax, %eax # Check for return code |
| 55 | jnz no_longmode |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 56 | |
| 57 | mov %cs, %ax |
| 58 | movzx %ax, %esi # Find the 32bit trampoline location |
| 59 | shll $4, %esi |
| 60 | |
| 61 | # Fixup the vectors |
| 62 | addl %esi, startup_32_vector - r_base |
| 63 | addl %esi, startup_64_vector - r_base |
| 64 | addl %esi, tgdt + 2 - r_base # Fixup the gdt pointer |
| 65 | |
Vivek Goyal | 983d5db | 2006-01-12 03:35:20 +0100 | [diff] [blame] | 66 | /* |
| 67 | * GDT tables in non default location kernel can be beyond 16MB and |
| 68 | * lgdt will not be able to load the address as in real mode default |
| 69 | * operand size is 16bit. Use lgdtl instead to force operand size |
| 70 | * to 32 bit. |
| 71 | */ |
| 72 | |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 73 | lidtl tidt - r_base # load idt with 0, 0 |
| 74 | lgdtl tgdt - r_base # load gdt with whatever is appropriate |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | |
| 76 | xor %ax, %ax |
| 77 | inc %ax # protected mode (PE) bit |
| 78 | lmsw %ax # into protected mode |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 79 | |
| 80 | # flush prefetch and jump to startup_32 |
| 81 | ljmpl *(startup_32_vector - r_base) |
| 82 | |
| 83 | .code32 |
| 84 | .balign 4 |
| 85 | startup_32: |
| 86 | movl $__KERNEL_DS, %eax # Initialize the %ds segment register |
| 87 | movl %eax, %ds |
| 88 | |
| 89 | xorl %eax, %eax |
| 90 | btsl $5, %eax # Enable PAE mode |
| 91 | movl %eax, %cr4 |
| 92 | |
| 93 | # Setup trampoline 4 level pagetables |
| 94 | leal (trampoline_level4_pgt - r_base)(%esi), %eax |
| 95 | movl %eax, %cr3 |
| 96 | |
| 97 | movl $MSR_EFER, %ecx |
| 98 | movl $(1 << _EFER_LME), %eax # Enable Long Mode |
| 99 | xorl %edx, %edx |
| 100 | wrmsr |
| 101 | |
| 102 | xorl %eax, %eax |
| 103 | btsl $31, %eax # Enable paging and in turn activate Long Mode |
| 104 | btsl $0, %eax # Enable protected mode |
| 105 | movl %eax, %cr0 |
| 106 | |
| 107 | /* |
| 108 | * At this point we're in long mode but in 32bit compatibility mode |
| 109 | * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn |
| 110 | * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use |
| 111 | * the new gdt/idt that has __KERNEL_CS with CS.L = 1. |
| 112 | */ |
| 113 | ljmp *(startup_64_vector - r_base)(%esi) |
| 114 | |
| 115 | .code64 |
| 116 | .balign 4 |
| 117 | startup_64: |
| 118 | # Now jump into the kernel using virtual addresses |
| 119 | movq $secondary_startup_64, %rax |
| 120 | jmp *%rax |
| 121 | |
| 122 | .code16 |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 123 | no_longmode: |
| 124 | hlt |
| 125 | jmp no_longmode |
Thomas Gleixner | e0a84f6 | 2007-10-11 11:15:19 +0200 | [diff] [blame] | 126 | #include "verify_cpu_64.S" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | |
| 128 | # Careful these need to be in the same 64K segment as the above; |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 129 | tidt: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 130 | .word 0 # idt limit = 0 |
| 131 | .word 0, 0 # idt base = 0L |
| 132 | |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 133 | # Duplicate the global descriptor table |
| 134 | # so the kernel can live anywhere |
| 135 | .balign 4 |
| 136 | tgdt: |
| 137 | .short tgdt_end - tgdt # gdt limit |
| 138 | .long tgdt - r_base |
| 139 | .short 0 |
| 140 | .quad 0x00cf9b000000ffff # __KERNEL32_CS |
| 141 | .quad 0x00af9b000000ffff # __KERNEL_CS |
| 142 | .quad 0x00cf93000000ffff # __KERNEL_DS |
| 143 | tgdt_end: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 144 | |
Vivek Goyal | 90b1c20 | 2007-05-02 19:27:07 +0200 | [diff] [blame] | 145 | .balign 4 |
| 146 | startup_32_vector: |
| 147 | .long startup_32 - r_base |
| 148 | .word __KERNEL32_CS, 0 |
| 149 | |
| 150 | .balign 4 |
| 151 | startup_64_vector: |
| 152 | .long startup_64 - r_base |
| 153 | .word __KERNEL_CS, 0 |
| 154 | |
| 155 | trampoline_stack: |
| 156 | .org 0x1000 |
| 157 | trampoline_stack_end: |
| 158 | ENTRY(trampoline_level4_pgt) |
| 159 | .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE |
| 160 | .fill 510,8,0 |
| 161 | .quad level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE |
| 162 | |
| 163 | ENTRY(trampoline_end) |