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1da177e4 LT |
1 | /* |
2 | * Copyright (C) Paul Mackerras 1997. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version | |
7 | * 2 of the License, or (at your option) any later version. | |
8 | * | |
6975a783 ME |
9 | * NOTE: this code runs in 32 bit mode, is position-independent, |
10 | * and is packaged as ELF32. | |
1da177e4 LT |
11 | */ |
12 | ||
decd300b | 13 | #include "ppc_asm.h" |
1da177e4 LT |
14 | |
15 | .text | |
6975a783 ME |
16 | /* A procedure descriptor used when booting this as a COFF file. |
17 | * When making COFF, this comes first in the link and we're | |
18 | * linked at 0x500000. | |
19 | */ | |
f40e524e | 20 | .globl _zimage_start_opd |
66a45dd3 | 21 | _zimage_start_opd: |
6975a783 ME |
22 | .long 0x500000, 0, 0, 0 |
23 | ||
24 | p_start: .long _start | |
25 | p_etext: .long _etext | |
26 | p_bss_start: .long __bss_start | |
27 | p_end: .long _end | |
28 | ||
29 | .weak _platform_stack_top | |
30 | p_pstack: .long _platform_stack_top | |
66a45dd3 | 31 | |
cd197ffc | 32 | .weak _zimage_start |
67a1b682 OH |
33 | .globl _zimage_start |
34 | _zimage_start: | |
160cc3ec MM |
35 | .globl _zimage_start_lib |
36 | _zimage_start_lib: | |
66a45dd3 PM |
37 | /* Work out the offset between the address we were linked at |
38 | and the address where we're running. */ | |
6975a783 ME |
39 | bl .+4 |
40 | p_base: mflr r10 /* r10 now points to runtime addr of p_base */ | |
41 | /* grab the link address of the dynamic section in r11 */ | |
42 | addis r11,r10,(_GLOBAL_OFFSET_TABLE_-p_base)@ha | |
43 | lwz r11,(_GLOBAL_OFFSET_TABLE_-p_base)@l(r11) | |
44 | cmpwi r11,0 | |
45 | beq 3f /* if not linked -pie */ | |
46 | /* get the runtime address of the dynamic section in r12 */ | |
47 | .weak __dynamic_start | |
48 | addis r12,r10,(__dynamic_start-p_base)@ha | |
49 | addi r12,r12,(__dynamic_start-p_base)@l | |
50 | subf r11,r11,r12 /* runtime - linktime offset */ | |
51 | ||
52 | /* The dynamic section contains a series of tagged entries. | |
53 | * We need the RELA and RELACOUNT entries. */ | |
54 | RELA = 7 | |
55 | RELACOUNT = 0x6ffffff9 | |
56 | li r9,0 | |
57 | li r0,0 | |
58 | 9: lwz r8,0(r12) /* get tag */ | |
59 | cmpwi r8,0 | |
60 | beq 10f /* end of list */ | |
61 | cmpwi r8,RELA | |
62 | bne 11f | |
63 | lwz r9,4(r12) /* get RELA pointer in r9 */ | |
64 | b 12f | |
65 | 11: addis r8,r8,(-RELACOUNT)@ha | |
66 | cmpwi r8,RELACOUNT@l | |
67 | bne 12f | |
68 | lwz r0,4(r12) /* get RELACOUNT value in r0 */ | |
69 | 12: addi r12,r12,8 | |
70 | b 9b | |
a4497235 | 71 | |
6975a783 ME |
72 | /* The relocation section contains a list of relocations. |
73 | * We now do the R_PPC_RELATIVE ones, which point to words | |
74 | * which need to be initialized with addend + offset. | |
75 | * The R_PPC_RELATIVE ones come first and there are RELACOUNT | |
76 | * of them. */ | |
77 | 10: /* skip relocation if we don't have both */ | |
78 | cmpwi r0,0 | |
68643cfb | 79 | beq 3f |
6975a783 ME |
80 | cmpwi r9,0 |
81 | beq 3f | |
82 | ||
83 | add r9,r9,r11 /* Relocate RELA pointer */ | |
84 | mtctr r0 | |
85 | 2: lbz r0,4+3(r9) /* ELF32_R_INFO(reloc->r_info) */ | |
86 | cmpwi r0,22 /* R_PPC_RELATIVE */ | |
87 | bne 3f | |
88 | lwz r12,0(r9) /* reloc->r_offset */ | |
89 | lwz r0,8(r9) /* reloc->r_addend */ | |
90 | add r0,r0,r11 | |
91 | stwx r0,r11,r12 | |
92 | addi r9,r9,12 | |
68643cfb | 93 | bdnz 2b |
a4497235 | 94 | |
cd197ffc | 95 | /* Do a cache flush for our text, in case the loader didn't */ |
6975a783 ME |
96 | 3: lwz r9,p_start-p_base(r10) /* note: these are relocated now */ |
97 | lwz r8,p_etext-p_base(r10) | |
68643cfb | 98 | 4: dcbf r0,r9 |
1da177e4 LT |
99 | icbi r0,r9 |
100 | addi r9,r9,0x20 | |
eacb1962 | 101 | cmplw cr0,r9,r8 |
68643cfb | 102 | blt 4b |
1da177e4 LT |
103 | sync |
104 | isync | |
105 | ||
cd197ffc | 106 | /* Clear the BSS */ |
6975a783 ME |
107 | lwz r9,p_bss_start-p_base(r10) |
108 | lwz r8,p_end-p_base(r10) | |
109 | li r0,0 | |
110 | 5: stw r0,0(r9) | |
cd197ffc DG |
111 | addi r9,r9,4 |
112 | cmplw cr0,r9,r8 | |
113 | blt 5b | |
1da177e4 | 114 | |
cd197ffc | 115 | /* Possibly set up a custom stack */ |
6975a783 | 116 | lwz r8,p_pstack-p_base(r10) |
cd197ffc DG |
117 | cmpwi r8,0 |
118 | beq 6f | |
119 | lwz r1,0(r8) | |
120 | li r0,0 | |
121 | stwu r0,-16(r1) /* establish a stack frame */ | |
122 | 6: | |
123 | ||
124 | /* Call platform_init() */ | |
125 | bl platform_init | |
126 | ||
127 | /* Call start */ | |
cd197ffc | 128 | b start |