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 *  Copyright (C) 2005 Thiemo Seufer
 19 *  Copyright (C) 2015 Imagination Technologies Ltd.
 20 */
 21
 22#include <linux/elf.h>
 23#include <linux/err.h>
 24#include <linux/errno.h>
 25#include <linux/moduleloader.h>
 26
 27extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);
 28
 29static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
 30{
 31	*location = v;
 32
 33	return 0;
 34}
 35
 36static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
 37{
 38	if (v % 4) {
 39		pr_err("module %s: dangerous R_MIPS_26 RELA relocation\n",
 40		       me->name);
 41		return -ENOEXEC;
 42	}
 43
 44	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 45		pr_err("module %s: relocation overflow\n", me->name);
 46		return -ENOEXEC;
 47	}
 48
 49	*location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
 50
 51	return 0;
 52}
 53
 54static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
 55{
 56	*location = (*location & 0xffff0000) |
 57		    ((((long long) v + 0x8000LL) >> 16) & 0xffff);
 58
 59	return 0;
 60}
 61
 62static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
 63{
 64	*location = (*location & 0xffff0000) | (v & 0xffff);
 65
 66	return 0;
 67}
 68
 69static int apply_r_mips_pc_rela(struct module *me, u32 *location, Elf_Addr v,
 70				unsigned bits)
 71{
 72	unsigned long mask = GENMASK(bits - 1, 0);
 73	unsigned long se_bits;
 74	long offset;
 75
 76	if (v % 4) {
 77		pr_err("module %s: dangerous R_MIPS_PC%u RELA relocation\n",
 78		       me->name, bits);
 79		return -ENOEXEC;
 80	}
 81
 82	offset = ((long)v - (long)location) >> 2;
 83
 84	/* check the sign bit onwards are identical - ie. we didn't overflow */
 85	se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
 86	if ((offset & ~mask) != (se_bits & ~mask)) {
 87		pr_err("module %s: relocation overflow\n", me->name);
 88		return -ENOEXEC;
 89	}
 90
 91	*location = (*location & ~mask) | (offset & mask);
 92
 93	return 0;
 94}
 95
 96static int apply_r_mips_pc16_rela(struct module *me, u32 *location, Elf_Addr v)
 97{
 98	return apply_r_mips_pc_rela(me, location, v, 16);
 99}
100
101static int apply_r_mips_pc21_rela(struct module *me, u32 *location, Elf_Addr v)
102{
103	return apply_r_mips_pc_rela(me, location, v, 21);
104}
105
106static int apply_r_mips_pc26_rela(struct module *me, u32 *location, Elf_Addr v)
107{
108	return apply_r_mips_pc_rela(me, location, v, 26);
109}
110
111static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
112{
113	*(Elf_Addr *)location = v;
114
115	return 0;
116}
117
118static int apply_r_mips_higher_rela(struct module *me, u32 *location,
119				    Elf_Addr v)
120{
121	*location = (*location & 0xffff0000) |
122		    ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
123
124	return 0;
125}
126
127static int apply_r_mips_highest_rela(struct module *me, u32 *location,
128				     Elf_Addr v)
129{
130	*location = (*location & 0xffff0000) |
131		    ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
132
133	return 0;
134}
135
136static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
137				Elf_Addr v) = {
138	[R_MIPS_NONE]		= apply_r_mips_none,
139	[R_MIPS_32]		= apply_r_mips_32_rela,
140	[R_MIPS_26]		= apply_r_mips_26_rela,
141	[R_MIPS_HI16]		= apply_r_mips_hi16_rela,
142	[R_MIPS_LO16]		= apply_r_mips_lo16_rela,
143	[R_MIPS_PC16]		= apply_r_mips_pc16_rela,
144	[R_MIPS_64]		= apply_r_mips_64_rela,
145	[R_MIPS_HIGHER]		= apply_r_mips_higher_rela,
146	[R_MIPS_HIGHEST]	= apply_r_mips_highest_rela,
147	[R_MIPS_PC21_S2]	= apply_r_mips_pc21_rela,
148	[R_MIPS_PC26_S2]	= apply_r_mips_pc26_rela,
149};
150
151int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
152		       unsigned int symindex, unsigned int relsec,
153		       struct module *me)
154{
155	Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
156	int (*handler)(struct module *me, u32 *location, Elf_Addr v);
157	Elf_Sym *sym;
158	u32 *location;
159	unsigned int i, type;
160	Elf_Addr v;
161	int res;
162
163	pr_debug("Applying relocate section %u to %u\n", relsec,
164	       sechdrs[relsec].sh_info);
165
166	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
167		/* This is where to make the change */
168		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
169			+ rel[i].r_offset;
170		/* This is the symbol it is referring to */
171		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
172			+ ELF_MIPS_R_SYM(rel[i]);
173		if (sym->st_value >= -MAX_ERRNO) {
174			/* Ignore unresolved weak symbol */
175			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
176				continue;
177			pr_warn("%s: Unknown symbol %s\n",
178			       me->name, strtab + sym->st_name);
179			return -ENOENT;
180		}
181
182		type = ELF_MIPS_R_TYPE(rel[i]);
183
184		if (type < ARRAY_SIZE(reloc_handlers_rela))
185			handler = reloc_handlers_rela[type];
186		else
187			handler = NULL;
188
189		if (!handler) {
190			pr_err("%s: Unknown relocation type %u\n",
191			       me->name, type);
192			return -EINVAL;
193		}
194
195		v = sym->st_value + rel[i].r_addend;
196		res = handler(me, location, v);
197		if (res)
198			return res;
199	}
200
201	return 0;
202}