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1 /*  Kernel module help for i386.
2     Copyright (C) 2001 Rusty Russell.
3 
4     This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU General Public License as published by
6     the Free Software Foundation; either version 2 of the License, or
7     (at your option) any later version.
8 
9     This program is distributed in the hope that it will be useful,
10     but WITHOUT ANY WARRANTY; without even the implied warranty of
11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12     GNU General Public License for more details.
13 
14     You should have received a copy of the GNU General Public License
15     along with this program; if not, write to the Free Software
16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17 */
18 #include <linux/moduleloader.h>
19 #include <linux/elf.h>
20 #include <linux/vmalloc.h>
21 #include <linux/fs.h>
22 #include <linux/string.h>
23 #include <linux/kernel.h>
24 #include <linux/bug.h>
25 
26 #if 0
27 #define DEBUGP printk
28 #else
29 #define DEBUGP(fmt...)
30 #endif
31 
module_alloc(unsigned long size)32 void *module_alloc(unsigned long size)
33 {
34 	if (size == 0)
35 		return NULL;
36 	return vmalloc_exec(size);
37 }
38 
39 
40 /* Free memory returned from module_alloc */
module_free(struct module * mod,void * module_region)41 void module_free(struct module *mod, void *module_region)
42 {
43 	vfree(module_region);
44 	/* FIXME: If module_region == mod->init_region, trim exception
45            table entries. */
46 }
47 
48 /* We don't need anything special. */
module_frob_arch_sections(Elf_Ehdr * hdr,Elf_Shdr * sechdrs,char * secstrings,struct module * mod)49 int module_frob_arch_sections(Elf_Ehdr *hdr,
50 			      Elf_Shdr *sechdrs,
51 			      char *secstrings,
52 			      struct module *mod)
53 {
54 	return 0;
55 }
56 
apply_relocate(Elf32_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)57 int apply_relocate(Elf32_Shdr *sechdrs,
58 		   const char *strtab,
59 		   unsigned int symindex,
60 		   unsigned int relsec,
61 		   struct module *me)
62 {
63 	unsigned int i;
64 	Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
65 	Elf32_Sym *sym;
66 	uint32_t *location;
67 
68 	DEBUGP("Applying relocate section %u to %u\n", relsec,
69 	       sechdrs[relsec].sh_info);
70 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
71 		/* This is where to make the change */
72 		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
73 			+ rel[i].r_offset;
74 		/* This is the symbol it is referring to.  Note that all
75 		   undefined symbols have been resolved.  */
76 		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
77 			+ ELF32_R_SYM(rel[i].r_info);
78 
79 		switch (ELF32_R_TYPE(rel[i].r_info)) {
80 		case R_386_32:
81 			/* We add the value into the location given */
82 			*location += sym->st_value;
83 			break;
84 		case R_386_PC32:
85 			/* Add the value, subtract its postition */
86 			*location += sym->st_value - (uint32_t)location;
87 			break;
88 		default:
89 			printk(KERN_ERR "module %s: Unknown relocation: %u\n",
90 			       me->name, ELF32_R_TYPE(rel[i].r_info));
91 			return -ENOEXEC;
92 		}
93 	}
94 	return 0;
95 }
96 
apply_relocate_add(Elf32_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)97 int apply_relocate_add(Elf32_Shdr *sechdrs,
98 		       const char *strtab,
99 		       unsigned int symindex,
100 		       unsigned int relsec,
101 		       struct module *me)
102 {
103 	printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
104 	       me->name);
105 	return -ENOEXEC;
106 }
107 
module_finalize(const Elf_Ehdr * hdr,const Elf_Shdr * sechdrs,struct module * me)108 int module_finalize(const Elf_Ehdr *hdr,
109 		    const Elf_Shdr *sechdrs,
110 		    struct module *me)
111 {
112 	const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
113 		*para = NULL;
114 	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
115 
116 	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
117 		if (!strcmp(".text", secstrings + s->sh_name))
118 			text = s;
119 		if (!strcmp(".altinstructions", secstrings + s->sh_name))
120 			alt = s;
121 		if (!strcmp(".smp_locks", secstrings + s->sh_name))
122 			locks= s;
123 		if (!strcmp(".parainstructions", secstrings + s->sh_name))
124 			para = s;
125 	}
126 
127 	if (alt) {
128 		/* patch .altinstructions */
129 		void *aseg = (void *)alt->sh_addr;
130 		apply_alternatives(aseg, aseg + alt->sh_size);
131 	}
132 	if (locks && text) {
133 		void *lseg = (void *)locks->sh_addr;
134 		void *tseg = (void *)text->sh_addr;
135 		alternatives_smp_module_add(me, me->name,
136 					    lseg, lseg + locks->sh_size,
137 					    tseg, tseg + text->sh_size);
138 	}
139 
140 	if (para) {
141 		void *pseg = (void *)para->sh_addr;
142 		apply_paravirt(pseg, pseg + para->sh_size);
143 	}
144 
145 	return module_bug_finalize(hdr, sechdrs, me);
146 }
147 
module_arch_cleanup(struct module * mod)148 void module_arch_cleanup(struct module *mod)
149 {
150 	alternatives_smp_module_del(mod);
151 	module_bug_cleanup(mod);
152 }
153