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/arch/mips/kernel/module-elf32.c

https://bitbucket.org/evzijst/gittest
C | 250 lines | 158 code | 43 blank | 49 comment | 17 complexity | d7d72313dd2aa4522a5c6a5bbe9cf789 MD5 | raw file
  1/*
  2 *  This program is free software; you can redistribute it and/or modify
  3 *  it under the terms of the GNU General Public License as published by
  4 *  the Free Software Foundation; either version 2 of the License, or
  5 *  (at your option) any later version.
  6 *
  7 *  This program is distributed in the hope that it will be useful,
  8 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  9 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 10 *  GNU General Public License for more details.
 11 *
 12 *  You should have received a copy of the GNU General Public License
 13 *  along with this program; if not, write to the Free Software
 14 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 15 *
 16 *  Copyright (C) 2001 Rusty Russell.
 17 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
 18 */
 19
 20#undef DEBUG
 21
 22#include <linux/moduleloader.h>
 23#include <linux/elf.h>
 24#include <linux/vmalloc.h>
 25#include <linux/slab.h>
 26#include <linux/fs.h>
 27#include <linux/string.h>
 28#include <linux/kernel.h>
 29
 30struct mips_hi16 {
 31	struct mips_hi16 *next;
 32	Elf32_Addr *addr;
 33	Elf32_Addr value;
 34};
 35
 36static struct mips_hi16 *mips_hi16_list;
 37
 38void *module_alloc(unsigned long size)
 39{
 40	if (size == 0)
 41		return NULL;
 42	return vmalloc(size);
 43}
 44
 45
 46/* Free memory returned from module_alloc */
 47void module_free(struct module *mod, void *module_region)
 48{
 49	vfree(module_region);
 50	/* FIXME: If module_region == mod->init_region, trim exception
 51           table entries. */
 52}
 53
 54int module_frob_arch_sections(Elf_Ehdr *hdr,
 55			      Elf_Shdr *sechdrs,
 56			      char *secstrings,
 57			      struct module *mod)
 58{
 59	return 0;
 60}
 61
 62static int apply_r_mips_none(struct module *me, uint32_t *location,
 63	Elf32_Addr v)
 64{
 65	return 0;
 66}
 67
 68static int apply_r_mips_32(struct module *me, uint32_t *location,
 69	Elf32_Addr v)
 70{
 71	*location += v;
 72
 73	return 0;
 74}
 75
 76static int apply_r_mips_26(struct module *me, uint32_t *location,
 77	Elf32_Addr v)
 78{
 79	if (v % 4) {
 80		printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
 81		return -ENOEXEC;
 82	}
 83
 84	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 85		printk(KERN_ERR
 86		       "module %s: relocation overflow\n",
 87		       me->name);
 88		return -ENOEXEC;
 89	}
 90
 91	*location = (*location & ~0x03ffffff) |
 92	            ((*location + (v >> 2)) & 0x03ffffff);
 93
 94	return 0;
 95}
 96
 97static int apply_r_mips_hi16(struct module *me, uint32_t *location,
 98	Elf32_Addr v)
 99{
100	struct mips_hi16 *n;
101
102	/*
103	 * We cannot relocate this one now because we don't know the value of
104	 * the carry we need to add.  Save the information, and let LO16 do the
105	 * actual relocation.
106	 */
107	n = kmalloc(sizeof *n, GFP_KERNEL);
108	if (!n)
109		return -ENOMEM;
110
111	n->addr = location;
112	n->value = v;
113	n->next = mips_hi16_list;
114	mips_hi16_list = n;
115
116	return 0;
117}
118
119static int apply_r_mips_lo16(struct module *me, uint32_t *location,
120	Elf32_Addr v)
121{
122	unsigned long insnlo = *location;
123	Elf32_Addr val, vallo;
124
125	/* Sign extend the addend we extract from the lo insn.  */
126	vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
127
128	if (mips_hi16_list != NULL) {
129		struct mips_hi16 *l;
130
131		l = mips_hi16_list;
132		while (l != NULL) {
133			struct mips_hi16 *next;
134			unsigned long insn;
135
136			/*
137			 * The value for the HI16 had best be the same.
138			 */
139			if (v != l->value)
140				goto out_danger;
141
142			/*
143			 * Do the HI16 relocation.  Note that we actually don't
144			 * need to know anything about the LO16 itself, except
145			 * where to find the low 16 bits of the addend needed
146			 * by the LO16.
147			 */
148			insn = *l->addr;
149			val = ((insn & 0xffff) << 16) + vallo;
150			val += v;
151
152			/*
153			 * Account for the sign extension that will happen in
154			 * the low bits.
155			 */
156			val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
157
158			insn = (insn & ~0xffff) | val;
159			*l->addr = insn;
160
161			next = l->next;
162			kfree(l);
163			l = next;
164		}
165
166		mips_hi16_list = NULL;
167	}
168
169	/*
170	 * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
171	 */
172	val = v + vallo;
173	insnlo = (insnlo & ~0xffff) | (val & 0xffff);
174	*location = insnlo;
175
176	return 0;
177
178out_danger:
179	printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);
180
181	return -ENOEXEC;
182}
183
184static int (*reloc_handlers[]) (struct module *me, uint32_t *location,
185	Elf32_Addr v) = {
186	[R_MIPS_NONE]	= apply_r_mips_none,
187	[R_MIPS_32]	= apply_r_mips_32,
188	[R_MIPS_26]	= apply_r_mips_26,
189	[R_MIPS_HI16]	= apply_r_mips_hi16,
190	[R_MIPS_LO16]	= apply_r_mips_lo16
191};
192
193int apply_relocate(Elf32_Shdr *sechdrs,
194		   const char *strtab,
195		   unsigned int symindex,
196		   unsigned int relsec,
197		   struct module *me)
198{
199	Elf32_Rel *rel = (void *) sechdrs[relsec].sh_addr;
200	Elf32_Sym *sym;
201	uint32_t *location;
202	unsigned int i;
203	Elf32_Addr v;
204	int res;
205
206	pr_debug("Applying relocate section %u to %u\n", relsec,
207	       sechdrs[relsec].sh_info);
208
209	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
210		Elf32_Word r_info = rel[i].r_info;
211
212		/* This is where to make the change */
213		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
214			+ rel[i].r_offset;
215		/* This is the symbol it is referring to */
216		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
217			+ ELF32_R_SYM(r_info);
218		if (!sym->st_value) {
219			printk(KERN_WARNING "%s: Unknown symbol %s\n",
220			       me->name, strtab + sym->st_name);
221			return -ENOENT;
222		}
223
224		v = sym->st_value;
225
226		res = reloc_handlers[ELF32_R_TYPE(r_info)](me, location, v);
227		if (res)
228			return res;
229	}
230
231	return 0;
232}
233
234int apply_relocate_add(Elf32_Shdr *sechdrs,
235		       const char *strtab,
236		       unsigned int symindex,
237		       unsigned int relsec,
238		       struct module *me)
239{
240	/*
241	 * Current binutils always generate .rela relocations.  Keep smiling
242	 * if it's empty, abort otherwise.
243	 */
244	if (!sechdrs[relsec].sh_size)
245		return 0;
246
247	printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
248	       me->name);
249	return -ENOEXEC;
250}