diff options
author | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
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committer | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
commit | fcc9d2e5a6c89d22b8b773a64fb4ad21ac318446 (patch) | |
tree | a57612d1888735a2ec7972891b68c1ac5ec8faea /arch/x86/kernel/trampoline_64.S | |
parent | 8dea78da5cee153b8af9c07a2745f6c55057fe12 (diff) |
Diffstat (limited to 'arch/x86/kernel/trampoline_64.S')
-rw-r--r-- | arch/x86/kernel/trampoline_64.S | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/kernel/trampoline_64.S new file mode 100644 index 00000000000..09ff51799e9 --- /dev/null +++ b/arch/x86/kernel/trampoline_64.S | |||
@@ -0,0 +1,171 @@ | |||
1 | /* | ||
2 | * | ||
3 | * Trampoline.S Derived from Setup.S by Linus Torvalds | ||
4 | * | ||
5 | * 4 Jan 1997 Michael Chastain: changed to gnu as. | ||
6 | * 15 Sept 2005 Eric Biederman: 64bit PIC support | ||
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 | * | ||
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 | * | ||
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 | * | ||
22 | * If you work on this file, check the object module with objdump | ||
23 | * --full-contents --reloc to make sure there are no relocation | ||
24 | * entries. | ||
25 | */ | ||
26 | |||
27 | #include <linux/linkage.h> | ||
28 | #include <linux/init.h> | ||
29 | #include <asm/pgtable_types.h> | ||
30 | #include <asm/page_types.h> | ||
31 | #include <asm/msr.h> | ||
32 | #include <asm/segment.h> | ||
33 | #include <asm/processor-flags.h> | ||
34 | |||
35 | .section ".x86_trampoline","a" | ||
36 | .balign PAGE_SIZE | ||
37 | .code16 | ||
38 | |||
39 | ENTRY(trampoline_data) | ||
40 | r_base = . | ||
41 | cli # We should be safe anyway | ||
42 | wbinvd | ||
43 | mov %cs, %ax # Code and data in the same place | ||
44 | mov %ax, %ds | ||
45 | mov %ax, %es | ||
46 | mov %ax, %ss | ||
47 | |||
48 | |||
49 | movl $0xA5A5A5A5, trampoline_status - r_base | ||
50 | # write marker for master knows we're running | ||
51 | |||
52 | # Setup stack | ||
53 | movw $(trampoline_stack_end - r_base), %sp | ||
54 | |||
55 | call verify_cpu # Verify the cpu supports long mode | ||
56 | testl %eax, %eax # Check for return code | ||
57 | jnz no_longmode | ||
58 | |||
59 | mov %cs, %ax | ||
60 | movzx %ax, %esi # Find the 32bit trampoline location | ||
61 | shll $4, %esi | ||
62 | |||
63 | # Fixup the absolute vectors | ||
64 | leal (startup_32 - r_base)(%esi), %eax | ||
65 | movl %eax, startup_32_vector - r_base | ||
66 | leal (startup_64 - r_base)(%esi), %eax | ||
67 | movl %eax, startup_64_vector - r_base | ||
68 | leal (tgdt - r_base)(%esi), %eax | ||
69 | movl %eax, (tgdt + 2 - r_base) | ||
70 | |||
71 | /* | ||
72 | * GDT tables in non default location kernel can be beyond 16MB and | ||
73 | * lgdt will not be able to load the address as in real mode default | ||
74 | * operand size is 16bit. Use lgdtl instead to force operand size | ||
75 | * to 32 bit. | ||
76 | */ | ||
77 | |||
78 | lidtl tidt - r_base # load idt with 0, 0 | ||
79 | lgdtl tgdt - r_base # load gdt with whatever is appropriate | ||
80 | |||
81 | mov $X86_CR0_PE, %ax # protected mode (PE) bit | ||
82 | lmsw %ax # into protected mode | ||
83 | |||
84 | # flush prefetch and jump to startup_32 | ||
85 | ljmpl *(startup_32_vector - r_base) | ||
86 | |||
87 | .code32 | ||
88 | .balign 4 | ||
89 | startup_32: | ||
90 | movl $__KERNEL_DS, %eax # Initialize the %ds segment register | ||
91 | movl %eax, %ds | ||
92 | |||
93 | movl $X86_CR4_PAE, %eax | ||
94 | movl %eax, %cr4 # Enable PAE mode | ||
95 | |||
96 | # Setup trampoline 4 level pagetables | ||
97 | leal (trampoline_level4_pgt - r_base)(%esi), %eax | ||
98 | movl %eax, %cr3 | ||
99 | |||
100 | movl $MSR_EFER, %ecx | ||
101 | movl $(1 << _EFER_LME), %eax # Enable Long Mode | ||
102 | xorl %edx, %edx | ||
103 | wrmsr | ||
104 | |||
105 | # Enable paging and in turn activate Long Mode | ||
106 | # Enable protected mode | ||
107 | movl $(X86_CR0_PG | X86_CR0_PE), %eax | ||
108 | movl %eax, %cr0 | ||
109 | |||
110 | /* | ||
111 | * At this point we're in long mode but in 32bit compatibility mode | ||
112 | * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn | ||
113 | * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use | ||
114 | * the new gdt/idt that has __KERNEL_CS with CS.L = 1. | ||
115 | */ | ||
116 | ljmp *(startup_64_vector - r_base)(%esi) | ||
117 | |||
118 | .code64 | ||
119 | .balign 4 | ||
120 | startup_64: | ||
121 | # Now jump into the kernel using virtual addresses | ||
122 | movq $secondary_startup_64, %rax | ||
123 | jmp *%rax | ||
124 | |||
125 | .code16 | ||
126 | no_longmode: | ||
127 | hlt | ||
128 | jmp no_longmode | ||
129 | #include "verify_cpu.S" | ||
130 | |||
131 | .balign 4 | ||
132 | # Careful these need to be in the same 64K segment as the above; | ||
133 | tidt: | ||
134 | .word 0 # idt limit = 0 | ||
135 | .word 0, 0 # idt base = 0L | ||
136 | |||
137 | # Duplicate the global descriptor table | ||
138 | # so the kernel can live anywhere | ||
139 | .balign 4 | ||
140 | tgdt: | ||
141 | .short tgdt_end - tgdt # gdt limit | ||
142 | .long tgdt - r_base | ||
143 | .short 0 | ||
144 | .quad 0x00cf9b000000ffff # __KERNEL32_CS | ||
145 | .quad 0x00af9b000000ffff # __KERNEL_CS | ||
146 | .quad 0x00cf93000000ffff # __KERNEL_DS | ||
147 | tgdt_end: | ||
148 | |||
149 | .balign 4 | ||
150 | startup_32_vector: | ||
151 | .long startup_32 - r_base | ||
152 | .word __KERNEL32_CS, 0 | ||
153 | |||
154 | .balign 4 | ||
155 | startup_64_vector: | ||
156 | .long startup_64 - r_base | ||
157 | .word __KERNEL_CS, 0 | ||
158 | |||
159 | .balign 4 | ||
160 | ENTRY(trampoline_status) | ||
161 | .long 0 | ||
162 | |||
163 | trampoline_stack: | ||
164 | .org 0x1000 | ||
165 | trampoline_stack_end: | ||
166 | ENTRY(trampoline_level4_pgt) | ||
167 | .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE | ||
168 | .fill 510,8,0 | ||
169 | .quad level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE | ||
170 | |||
171 | ENTRY(trampoline_end) | ||