1/* MN10300 Kernel module helper routines
2 *
3 * Copyright (C) 2007, 2008, 2009 Red Hat, Inc. All Rights Reserved.
4 * Written by Mark Salter (msalter@redhat.com)
5 * - Derived from arch/i386/kernel/module.c
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public Licence as published by
9 * the Free Software Foundation; either version 2 of the Licence, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public Licence for more details.
16 *
17 * You should have received a copy of the GNU General Public Licence
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21#include <linux/moduleloader.h>
22#include <linux/elf.h>
23#include <linux/vmalloc.h>
24#include <linux/fs.h>
25#include <linux/string.h>
26#include <linux/kernel.h>
27#include <linux/bug.h>
28
29#if 0
30#define DEBUGP printk
31#else
32#define DEBUGP(fmt, ...)
33#endif
34
35static void reloc_put16(uint8_t *p, uint32_t val)
36{
37	p[0] = val & 0xff;
38	p[1] = (val >> 8) & 0xff;
39}
40
41static void reloc_put24(uint8_t *p, uint32_t val)
42{
43	reloc_put16(p, val);
44	p[2] = (val >> 16) & 0xff;
45}
46
47static void reloc_put32(uint8_t *p, uint32_t val)
48{
49	reloc_put16(p, val);
50	reloc_put16(p+2, val >> 16);
51}
52
53/*
54 * apply a RELA relocation
55 */
56int apply_relocate_add(Elf32_Shdr *sechdrs,
57		       const char *strtab,
58		       unsigned int symindex,
59		       unsigned int relsec,
60		       struct module *me)
61{
62	unsigned int i, sym_diff_seen = 0;
63	Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
64	Elf32_Sym *sym;
65	Elf32_Addr relocation, sym_diff_val = 0;
66	uint8_t *location;
67	uint32_t value;
68
69	DEBUGP("Applying relocate section %u to %u\n",
70	       relsec, sechdrs[relsec].sh_info);
71
72	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
73		/* this is where to make the change */
74		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
75			+ rel[i].r_offset;
76
77		/* this is the symbol the relocation is referring to (note that
78		 * all undefined symbols have been resolved by the caller) */
79		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
80			+ ELF32_R_SYM(rel[i].r_info);
81
82		/* this is the adjustment to be made */
83		relocation = sym->st_value + rel[i].r_addend;
84
85		if (sym_diff_seen) {
86			switch (ELF32_R_TYPE(rel[i].r_info)) {
87			case R_MN10300_32:
88			case R_MN10300_24:
89			case R_MN10300_16:
90			case R_MN10300_8:
91				relocation -= sym_diff_val;
92				sym_diff_seen = 0;
93				break;
94			default:
95				printk(KERN_ERR "module %s: Unexpected SYM_DIFF relocation: %u\n",
96				       me->name, ELF32_R_TYPE(rel[i].r_info));
97				return -ENOEXEC;
98			}
99		}
100
101		switch (ELF32_R_TYPE(rel[i].r_info)) {
102			/* for the first four relocation types, we simply
103			 * store the adjustment at the location given */
104		case R_MN10300_32:
105			reloc_put32(location, relocation);
106			break;
107		case R_MN10300_24:
108			reloc_put24(location, relocation);
109			break;
110		case R_MN10300_16:
111			reloc_put16(location, relocation);
112			break;
113		case R_MN10300_8:
114			*location = relocation;
115			break;
116
117			/* for the next three relocation types, we write the
118			 * adjustment with the address subtracted over the
119			 * value at the location given */
120		case R_MN10300_PCREL32:
121			value = relocation - (uint32_t) location;
122			reloc_put32(location, value);
123			break;
124		case R_MN10300_PCREL16:
125			value = relocation - (uint32_t) location;
126			reloc_put16(location, value);
127			break;
128		case R_MN10300_PCREL8:
129			*location = relocation - (uint32_t) location;
130			break;
131
132		case R_MN10300_SYM_DIFF:
133			/* This is used to adjust the next reloc as required
134			 * by relaxation. */
135			sym_diff_seen = 1;
136			sym_diff_val = sym->st_value;
137			break;
138
139		case R_MN10300_ALIGN:
140			/* Just ignore the ALIGN relocs.
141			 * Only interesting if kernel performed relaxation. */
142			continue;
143
144		default:
145			printk(KERN_ERR "module %s: Unknown relocation: %u\n",
146			       me->name, ELF32_R_TYPE(rel[i].r_info));
147			return -ENOEXEC;
148		}
149	}
150	if (sym_diff_seen) {
151		printk(KERN_ERR "module %s: Nothing follows SYM_DIFF relocation: %u\n",
152				       me->name, ELF32_R_TYPE(rel[i].r_info));
153		return -ENOEXEC;
154	}
155	return 0;
156}
157