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Commit | Line | Data |
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cc90b958 BS |
1 | Subject: kexec: Move asm segment handling code to the assembly file (i386) |
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 | 59 ----------------------------------------------------- | |
21 | relocate_kernel.S | 58 +++++++++++++++++++++++++++++++++++++++++++++++----- | |
22 | 2 files changed, 53 insertions(+), 64 deletions(-) | |
23 | ||
24 | Index: head-2008-11-17/arch/x86/kernel/machine_kexec_32.c | |
25 | =================================================================== | |
26 | --- head-2008-11-17.orig/arch/x86/kernel/machine_kexec_32.c 2008-11-17 13:15:56.000000000 +0100 | |
27 | +++ head-2008-11-17/arch/x86/kernel/machine_kexec_32.c 2008-11-17 13:38:03.000000000 +0100 | |
28 | @@ -34,48 +34,6 @@ static u32 kexec_pmd1[1024] PAGE_ALIGNED | |
29 | static u32 kexec_pte0[1024] PAGE_ALIGNED; | |
30 | static u32 kexec_pte1[1024] PAGE_ALIGNED; | |
31 | ||
32 | -static void set_idt(void *newidt, __u16 limit) | |
33 | -{ | |
34 | - struct desc_ptr curidt; | |
35 | - | |
36 | - /* ia32 supports unaliged loads & stores */ | |
37 | - curidt.size = limit; | |
38 | - curidt.address = (unsigned long)newidt; | |
39 | - | |
40 | - load_idt(&curidt); | |
41 | -} | |
42 | - | |
43 | - | |
44 | -static void set_gdt(void *newgdt, __u16 limit) | |
45 | -{ | |
46 | - struct desc_ptr curgdt; | |
47 | - | |
48 | - /* ia32 supports unaligned loads & stores */ | |
49 | - curgdt.size = limit; | |
50 | - curgdt.address = (unsigned long)newgdt; | |
51 | - | |
52 | - load_gdt(&curgdt); | |
53 | -} | |
54 | - | |
55 | -static void load_segments(void) | |
56 | -{ | |
57 | -#define __STR(X) #X | |
58 | -#define STR(X) __STR(X) | |
59 | - | |
60 | - __asm__ __volatile__ ( | |
61 | - "\tljmp $"STR(__KERNEL_CS)",$1f\n" | |
62 | - "\t1:\n" | |
63 | - "\tmovl $"STR(__KERNEL_DS)",%%eax\n" | |
64 | - "\tmovl %%eax,%%ds\n" | |
65 | - "\tmovl %%eax,%%es\n" | |
66 | - "\tmovl %%eax,%%fs\n" | |
67 | - "\tmovl %%eax,%%gs\n" | |
68 | - "\tmovl %%eax,%%ss\n" | |
69 | - ::: "eax", "memory"); | |
70 | -#undef STR | |
71 | -#undef __STR | |
72 | -} | |
73 | - | |
74 | /* | |
75 | * A architecture hook called to validate the | |
76 | * proposed image and prepare the control pages | |
77 | @@ -167,23 +125,6 @@ void machine_kexec(struct kimage *image) | |
78 | page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) | |
79 | << PAGE_SHIFT); | |
80 | ||
81 | - /* The segment registers are funny things, they have both a | |
82 | - * visible and an invisible part. Whenever the visible part is | |
83 | - * set to a specific selector, the invisible part is loaded | |
84 | - * with from a table in memory. At no other time is the | |
85 | - * descriptor table in memory accessed. | |
86 | - * | |
87 | - * I take advantage of this here by force loading the | |
88 | - * segments, before I zap the gdt with an invalid value. | |
89 | - */ | |
90 | - load_segments(); | |
91 | - /* The gdt & idt are now invalid. | |
92 | - * If you want to load them you must set up your own idt & gdt. | |
93 | - */ | |
94 | - set_gdt(phys_to_virt(0),0); | |
95 | - set_idt(phys_to_virt(0),0); | |
96 | - | |
97 | - /* now call it */ | |
98 | image->start = relocate_kernel_ptr((unsigned long)image->head, | |
99 | (unsigned long)page_list, | |
100 | image->start, cpu_has_pae, | |
101 | Index: head-2008-11-17/arch/x86/kernel/relocate_kernel_32.S | |
102 | =================================================================== | |
103 | --- head-2008-11-17.orig/arch/x86/kernel/relocate_kernel_32.S 2008-11-17 13:15:56.000000000 +0100 | |
104 | +++ head-2008-11-17/arch/x86/kernel/relocate_kernel_32.S 2008-11-17 13:38:03.000000000 +0100 | |
105 | @@ -199,14 +199,45 @@ relocate_new_kernel: | |
106 | movl PTR(PA_PGD)(%ebp), %eax | |
107 | movl %eax, %cr3 | |
108 | ||
109 | + /* setup idt */ | |
110 | + movl %edi, %eax | |
111 | + addl $(idt_48 - relocate_kernel), %eax | |
112 | + lidtl (%eax) | |
113 | + | |
114 | + /* setup gdt */ | |
115 | + movl %edi, %eax | |
116 | + addl $(gdt - relocate_kernel), %eax | |
117 | + movl %edi, %esi | |
118 | + addl $((gdt_48 - relocate_kernel) + 2), %esi | |
119 | + movl %eax, (%esi) | |
120 | + | |
121 | + movl %edi, %eax | |
122 | + addl $(gdt_48 - relocate_kernel), %eax | |
123 | + lgdtl (%eax) | |
124 | + | |
125 | + /* setup data segment registers */ | |
126 | + mov $(gdt_ds - gdt), %eax | |
127 | + mov %eax, %ds | |
128 | + mov %eax, %es | |
129 | + mov %eax, %fs | |
130 | + mov %eax, %gs | |
131 | + mov %eax, %ss | |
132 | + | |
133 | /* setup a new stack at the end of the physical control page */ | |
134 | lea PAGE_SIZE(%edi), %esp | |
135 | ||
136 | - /* jump to identity mapped page */ | |
137 | - movl %edi, %eax | |
138 | - addl $(identity_mapped - relocate_kernel), %eax | |
139 | - pushl %eax | |
140 | - ret | |
141 | + /* load new code segment and jump to identity mapped page */ | |
142 | + movl %edi, %esi | |
143 | + xorl %eax, %eax | |
144 | + pushl %eax | |
145 | + pushl %esi | |
146 | + pushl %eax | |
147 | + movl $(gdt_cs - gdt), %eax | |
148 | + pushl %eax | |
149 | + movl %edi, %eax | |
150 | + addl $(identity_mapped - relocate_kernel),%eax | |
151 | + pushl %eax | |
152 | + iretl | |
153 | ||
154 | identity_mapped: | |
155 | /* store the start address on the stack */ | |
156 | @@ -378,5 +409,22 @@ swap_pages: | |
157 | popl %ebp | |
158 | ret | |
159 | ||
160 | + .align 16 | |
161 | +gdt: | |
162 | + .quad 0x0000000000000000 /* NULL descriptor */ | |
163 | +gdt_cs: | |
164 | + .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ | |
165 | +gdt_ds: | |
166 | + .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ | |
167 | +gdt_end: | |
168 | + | |
169 | +gdt_48: | |
170 | + .word gdt_end - gdt - 1 /* limit */ | |
171 | + .long 0 /* base - filled in by code above */ | |
172 | + | |
173 | +idt_48: | |
174 | + .word 0 /* limit */ | |
175 | + .long 0 /* base */ | |
176 | + | |
177 | .globl kexec_control_code_size | |
178 | .set kexec_control_code_size, . - relocate_kernel |