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1/*
2 * Kernel module loader for Hexagon
3 *
4 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA.
19 */
20
21#include <asm/module.h>
22#include <linux/elf.h>
23#include <linux/module.h>
24#include <linux/moduleloader.h>
25#include <linux/vmalloc.h>
26
27#if 0
28#define DEBUGP printk
29#else
30#define DEBUGP(fmt , ...)
31#endif
32
33/*
34 * module_frob_arch_sections - tweak got/plt sections.
35 * @hdr - pointer to elf header
36 * @sechdrs - pointer to elf load section headers
37 * @secstrings - symbol names
38 * @mod - pointer to module
39 */
40int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
41 char *secstrings,
42 struct module *mod)
43{
44 unsigned int i;
45 int found = 0;
46
47 /* Look for .plt and/or .got.plt and/or .init.plt sections */
48 for (i = 0; i < hdr->e_shnum; i++) {
49 DEBUGP("Section %d is %s\n", i,
50 secstrings + sechdrs[i].sh_name);
51 if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
52 found = i+1;
53 if (strcmp(secstrings + sechdrs[i].sh_name, ".got.plt") == 0)
54 found = i+1;
55 if (strcmp(secstrings + sechdrs[i].sh_name, ".rela.plt") == 0)
56 found = i+1;
57 }
58
59 /* At this time, we don't support modules comiled with -shared */
60 if (found) {
61 printk(KERN_WARNING
62 "Module '%s' contains unexpected .plt/.got sections.\n",
63 mod->name);
64 /* return -ENOEXEC; */
65 }
66
67 return 0;
68}
69
70/*
71 * apply_relocate_add - perform rela relocations.
72 * @sechdrs - pointer to section headers
73 * @strtab - some sort of start address?
74 * @symindex - symbol index offset or something?
75 * @relsec - address to relocate to?
76 * @module - pointer to module
77 *
78 * Perform rela relocations.
79 */
80int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
81 unsigned int symindex, unsigned int relsec,
82 struct module *module)
83{
84 unsigned int i;
85 Elf32_Sym *sym;
86 uint32_t *location;
87 uint32_t value;
88 unsigned int nrelocs = sechdrs[relsec].sh_size / sizeof(Elf32_Rela);
89 Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
90 Elf32_Word sym_info = sechdrs[relsec].sh_info;
91 Elf32_Sym *sym_base = (Elf32_Sym *) sechdrs[symindex].sh_addr;
92 void *loc_base = (void *) sechdrs[sym_info].sh_addr;
93
94 DEBUGP("Applying relocations in section %u to section %u base=%p\n",
95 relsec, sym_info, loc_base);
96
97 for (i = 0; i < nrelocs; i++) {
98
99 /* Symbol to relocate */
100 sym = sym_base + ELF32_R_SYM(rela[i].r_info);
101
102 /* Where to make the change */
103 location = loc_base + rela[i].r_offset;
104
105 /* `Everything is relative'. */
106 value = sym->st_value + rela[i].r_addend;
107
108 DEBUGP("%d: value=%08x loc=%p reloc=%d symbol=%s\n",
109 i, value, location, ELF32_R_TYPE(rela[i].r_info),
110 sym->st_name ?
111 &strtab[sym->st_name] : "(anonymous)");
112
113 switch (ELF32_R_TYPE(rela[i].r_info)) {
114 case R_HEXAGON_B22_PCREL: {
115 int dist = (int)(value - (uint32_t)location);
116 if ((dist < -0x00800000) ||
117 (dist >= 0x00800000)) {
118 printk(KERN_ERR
119 "%s: %s: %08x=%08x-%08x %s\n",
120 module->name,
121 "R_HEXAGON_B22_PCREL reloc out of range",
122 dist, value, (uint32_t)location,
123 sym->st_name ?
124 &strtab[sym->st_name] : "(anonymous)");
125 return -ENOEXEC;
126 }
127 DEBUGP("B22_PCREL contents: %08X.\n", *location);
128 *location &= ~0x01ff3fff;
129 *location |= 0x00003fff & dist;
130 *location |= 0x01ff0000 & (dist<<2);
131 DEBUGP("Contents after reloc: %08x\n", *location);
132 break;
133 }
134 case R_HEXAGON_HI16:
135 value = (value>>16) & 0xffff;
136 /* fallthrough */
137 case R_HEXAGON_LO16:
138 *location &= ~0x00c03fff;
139 *location |= value & 0x3fff;
140 *location |= (value & 0xc000) << 8;
141 break;
142 case R_HEXAGON_32:
143 *location = value;
144 break;
145 case R_HEXAGON_32_PCREL:
146 *location = value - (uint32_t)location;
147 break;
148 case R_HEXAGON_PLT_B22_PCREL:
149 case R_HEXAGON_GOTOFF_LO16:
150 case R_HEXAGON_GOTOFF_HI16:
151 printk(KERN_ERR "%s: GOT/PLT relocations unsupported\n",
152 module->name);
153 return -ENOEXEC;
154 default:
155 printk(KERN_ERR "%s: unknown relocation: %u\n",
156 module->name,
157 ELF32_R_TYPE(rela[i].r_info));
158 return -ENOEXEC;
159 }
160 }
161 return 0;
162}