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Commit | Line | Data |
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2cb7cef9 BS |
1 | Subject: kexec: Move asm segment handling code to the assembly file (x86_64) |
2 | From: http://xenbits.xensource.com/xen-unstable.hg (tip 13816) | |
3 | Patch-mainline: obsolete | |
4 | ||
5 | This patch moves the idt, gdt, and segment handling code from machine_kexec.c | |
6 | to relocate_kernel.S. The main reason behind this move is to avoid code | |
7 | duplication in the Xen hypervisor. With this patch all code required to kexec | |
8 | is put on the control page. | |
9 | ||
10 | On top of that this patch also counts as a cleanup - I think it is much | |
11 | nicer to write assembly directly in assembly files than wrap inline assembly | |
12 | in C functions for no apparent reason. | |
13 | ||
14 | Signed-off-by: Magnus Damm <magnus@valinux.co.jp> | |
15 | Acked-by: jbeulich@novell.com | |
16 | --- | |
17 | ||
18 | Applies to 2.6.19-rc1. | |
19 | ||
20 | machine_kexec.c | 58 ----------------------------------------------------- | |
21 | relocate_kernel.S | 50 +++++++++++++++++++++++++++++++++++++++++---- | |
22 | 2 files changed, 45 insertions(+), 63 deletions(-) | |
23 | ||
24 | Index: head-2008-08-18/arch/x86/kernel/machine_kexec_64.c | |
25 | =================================================================== | |
26 | --- head-2008-08-18.orig/arch/x86/kernel/machine_kexec_64.c 2008-08-18 09:05:04.000000000 +0200 | |
27 | +++ head-2008-08-18/arch/x86/kernel/machine_kexec_64.c 2008-08-18 10:13:08.000000000 +0200 | |
28 | @@ -115,47 +115,6 @@ static int init_pgtable(struct kimage *i | |
29 | return init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT); | |
30 | } | |
31 | ||
32 | -static void set_idt(void *newidt, u16 limit) | |
33 | -{ | |
34 | - struct desc_ptr curidt; | |
35 | - | |
36 | - /* x86-64 supports unaliged loads & stores */ | |
37 | - curidt.size = limit; | |
38 | - curidt.address = (unsigned long)newidt; | |
39 | - | |
40 | - __asm__ __volatile__ ( | |
41 | - "lidtq %0\n" | |
42 | - : : "m" (curidt) | |
43 | - ); | |
44 | -}; | |
45 | - | |
46 | - | |
47 | -static void set_gdt(void *newgdt, u16 limit) | |
48 | -{ | |
49 | - struct desc_ptr curgdt; | |
50 | - | |
51 | - /* x86-64 supports unaligned loads & stores */ | |
52 | - curgdt.size = limit; | |
53 | - curgdt.address = (unsigned long)newgdt; | |
54 | - | |
55 | - __asm__ __volatile__ ( | |
56 | - "lgdtq %0\n" | |
57 | - : : "m" (curgdt) | |
58 | - ); | |
59 | -}; | |
60 | - | |
61 | -static void load_segments(void) | |
62 | -{ | |
63 | - __asm__ __volatile__ ( | |
64 | - "\tmovl %0,%%ds\n" | |
65 | - "\tmovl %0,%%es\n" | |
66 | - "\tmovl %0,%%ss\n" | |
67 | - "\tmovl %0,%%fs\n" | |
68 | - "\tmovl %0,%%gs\n" | |
69 | - : : "a" (__KERNEL_DS) : "memory" | |
70 | - ); | |
71 | -} | |
72 | - | |
73 | int machine_kexec_prepare(struct kimage *image) | |
74 | { | |
75 | unsigned long start_pgtable; | |
76 | @@ -214,23 +173,6 @@ void machine_kexec(struct kimage *image) | |
77 | page_list[PA_TABLE_PAGE] = | |
78 | (unsigned long)__pa(page_address(image->control_code_page)); | |
79 | ||
80 | - /* The segment registers are funny things, they have both a | |
81 | - * visible and an invisible part. Whenever the visible part is | |
82 | - * set to a specific selector, the invisible part is loaded | |
83 | - * with from a table in memory. At no other time is the | |
84 | - * descriptor table in memory accessed. | |
85 | - * | |
86 | - * I take advantage of this here by force loading the | |
87 | - * segments, before I zap the gdt with an invalid value. | |
88 | - */ | |
89 | - load_segments(); | |
90 | - /* The gdt & idt are now invalid. | |
91 | - * If you want to load them you must set up your own idt & gdt. | |
92 | - */ | |
93 | - set_gdt(phys_to_virt(0),0); | |
94 | - set_idt(phys_to_virt(0),0); | |
95 | - | |
96 | - /* now call it */ | |
97 | relocate_kernel((unsigned long)image->head, (unsigned long)page_list, | |
98 | image->start); | |
99 | } | |
100 | Index: head-2008-08-18/arch/x86/kernel/relocate_kernel_64.S | |
101 | =================================================================== | |
102 | --- head-2008-08-18.orig/arch/x86/kernel/relocate_kernel_64.S 2008-07-13 23:51:29.000000000 +0200 | |
103 | +++ head-2008-08-18/arch/x86/kernel/relocate_kernel_64.S 2008-08-18 10:13:08.000000000 +0200 | |
104 | @@ -160,13 +160,39 @@ relocate_new_kernel: | |
105 | movq PTR(PA_PGD)(%rsi), %r9 | |
106 | movq %r9, %cr3 | |
107 | ||
108 | + /* setup idt */ | |
109 | + movq %r8, %rax | |
110 | + addq $(idt_80 - relocate_kernel), %rax | |
111 | + lidtq (%rax) | |
112 | + | |
113 | + /* setup gdt */ | |
114 | + movq %r8, %rax | |
115 | + addq $(gdt - relocate_kernel), %rax | |
116 | + movq %r8, %r9 | |
117 | + addq $((gdt_80 - relocate_kernel) + 2), %r9 | |
118 | + movq %rax, (%r9) | |
119 | + | |
120 | + movq %r8, %rax | |
121 | + addq $(gdt_80 - relocate_kernel), %rax | |
122 | + lgdtq (%rax) | |
123 | + | |
124 | + /* setup data segment registers */ | |
125 | + xorl %eax, %eax | |
126 | + movl %eax, %ds | |
127 | + movl %eax, %es | |
128 | + movl %eax, %fs | |
129 | + movl %eax, %gs | |
130 | + movl %eax, %ss | |
131 | + | |
132 | /* setup a new stack at the end of the physical control page */ | |
133 | lea PAGE_SIZE(%r8), %rsp | |
134 | ||
135 | - /* jump to identity mapped page */ | |
136 | - addq $(identity_mapped - relocate_kernel), %r8 | |
137 | - pushq %r8 | |
138 | - ret | |
139 | + /* load new code segment and jump to identity mapped page */ | |
140 | + movq %r8, %rax | |
141 | + addq $(identity_mapped - relocate_kernel), %rax | |
142 | + pushq $(gdt_cs - gdt) | |
143 | + pushq %rax | |
144 | + lretq | |
145 | ||
146 | identity_mapped: | |
147 | /* store the start address on the stack */ | |
148 | @@ -262,5 +288,19 @@ identity_mapped: | |
149 | xorq %r13, %r13 | |
150 | xorq %r14, %r14 | |
151 | xorq %r15, %r15 | |
152 | - | |
153 | ret | |
154 | + | |
155 | + .align 16 | |
156 | +gdt: | |
157 | + .quad 0x0000000000000000 /* NULL descriptor */ | |
158 | +gdt_cs: | |
159 | + .quad 0x00af9a000000ffff | |
160 | +gdt_end: | |
161 | + | |
162 | +gdt_80: | |
163 | + .word gdt_end - gdt - 1 /* limit */ | |
164 | + .quad 0 /* base - filled in by code above */ | |
165 | + | |
166 | +idt_80: | |
167 | + .word 0 /* limit */ | |
168 | + .quad 0 /* base */ |