1/*
2 * Kernel module loader for Hexagon
3 *
4 * Copyright (c) 2010-2011, The Linux Foundation. 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}
163