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_32.S | |
parent | 8dea78da5cee153b8af9c07a2745f6c55057fe12 (diff) |
Diffstat (limited to 'arch/x86/kernel/trampoline_32.S')
-rw-r--r-- | arch/x86/kernel/trampoline_32.S | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/arch/x86/kernel/trampoline_32.S b/arch/x86/kernel/trampoline_32.S new file mode 100644 index 00000000000..451c0a7ef7f --- /dev/null +++ b/arch/x86/kernel/trampoline_32.S | |||
@@ -0,0 +1,83 @@ | |||
1 | /* | ||
2 | * | ||
3 | * Trampoline.S Derived from Setup.S by Linus Torvalds | ||
4 | * | ||
5 | * 4 Jan 1997 Michael Chastain: changed to gnu as. | ||
6 | * | ||
7 | * This is only used for booting secondary CPUs in SMP machine | ||
8 | * | ||
9 | * Entry: CS:IP point to the start of our code, we are | ||
10 | * in real mode with no stack, but the rest of the | ||
11 | * trampoline page to make our stack and everything else | ||
12 | * is a mystery. | ||
13 | * | ||
14 | * We jump into arch/x86/kernel/head_32.S. | ||
15 | * | ||
16 | * On entry to trampoline_data, the processor is in real mode | ||
17 | * with 16-bit addressing and 16-bit data. CS has some value | ||
18 | * and IP is zero. Thus, data addresses need to be absolute | ||
19 | * (no relocation) and are taken with regard to r_base. | ||
20 | * | ||
21 | * If you work on this file, check the object module with | ||
22 | * objdump --reloc to make sure there are no relocation | ||
23 | * entries except for: | ||
24 | * | ||
25 | * TYPE VALUE | ||
26 | * R_386_32 startup_32_smp | ||
27 | * R_386_32 boot_gdt | ||
28 | */ | ||
29 | |||
30 | #include <linux/linkage.h> | ||
31 | #include <linux/init.h> | ||
32 | #include <asm/segment.h> | ||
33 | #include <asm/page_types.h> | ||
34 | |||
35 | #ifdef CONFIG_SMP | ||
36 | |||
37 | .section ".x86_trampoline","a" | ||
38 | .balign PAGE_SIZE | ||
39 | .code16 | ||
40 | |||
41 | ENTRY(trampoline_data) | ||
42 | r_base = . | ||
43 | wbinvd # Needed for NUMA-Q should be harmless for others | ||
44 | mov %cs, %ax # Code and data in the same place | ||
45 | mov %ax, %ds | ||
46 | |||
47 | cli # We should be safe anyway | ||
48 | |||
49 | movl $0xA5A5A5A5, trampoline_status - r_base | ||
50 | # write marker for master knows we're running | ||
51 | |||
52 | /* GDT tables in non default location kernel can be beyond 16MB and | ||
53 | * lgdt will not be able to load the address as in real mode default | ||
54 | * operand size is 16bit. Use lgdtl instead to force operand size | ||
55 | * to 32 bit. | ||
56 | */ | ||
57 | |||
58 | lidtl boot_idt_descr - r_base # load idt with 0, 0 | ||
59 | lgdtl boot_gdt_descr - r_base # load gdt with whatever is appropriate | ||
60 | |||
61 | xor %ax, %ax | ||
62 | inc %ax # protected mode (PE) bit | ||
63 | lmsw %ax # into protected mode | ||
64 | # flush prefetch and jump to startup_32_smp in arch/i386/kernel/head.S | ||
65 | ljmpl $__BOOT_CS, $(startup_32_smp-__PAGE_OFFSET) | ||
66 | |||
67 | # These need to be in the same 64K segment as the above; | ||
68 | # hence we don't use the boot_gdt_descr defined in head.S | ||
69 | boot_gdt_descr: | ||
70 | .word __BOOT_DS + 7 # gdt limit | ||
71 | .long boot_gdt - __PAGE_OFFSET # gdt base | ||
72 | |||
73 | boot_idt_descr: | ||
74 | .word 0 # idt limit = 0 | ||
75 | .long 0 # idt base = 0L | ||
76 | |||
77 | ENTRY(trampoline_status) | ||
78 | .long 0 | ||
79 | |||
80 | .globl trampoline_end | ||
81 | trampoline_end: | ||
82 | |||
83 | #endif /* CONFIG_SMP */ | ||