xref: /openbmc/linux/arch/hexagon/kernel/module.c (revision df561f66)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Kernel module loader for Hexagon
4  *
5  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
6  */
7 
8 #include <asm/module.h>
9 #include <linux/elf.h>
10 #include <linux/module.h>
11 #include <linux/moduleloader.h>
12 #include <linux/vmalloc.h>
13 
14 #if 0
15 #define DEBUGP printk
16 #else
17 #define DEBUGP(fmt , ...)
18 #endif
19 
20 /*
21  * module_frob_arch_sections - tweak got/plt sections.
22  * @hdr - pointer to elf header
23  * @sechdrs - pointer to elf load section headers
24  * @secstrings - symbol names
25  * @mod - pointer to module
26  */
module_frob_arch_sections(Elf_Ehdr * hdr,Elf_Shdr * sechdrs,char * secstrings,struct module * mod)27 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
28 				char *secstrings,
29 				struct module *mod)
30 {
31 	unsigned int i;
32 	int found = 0;
33 
34 	/* Look for .plt and/or .got.plt and/or .init.plt sections */
35 	for (i = 0; i < hdr->e_shnum; i++) {
36 		DEBUGP("Section %d is %s\n", i,
37 		       secstrings + sechdrs[i].sh_name);
38 		if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
39 			found = i+1;
40 		if (strcmp(secstrings + sechdrs[i].sh_name, ".got.plt") == 0)
41 			found = i+1;
42 		if (strcmp(secstrings + sechdrs[i].sh_name, ".rela.plt") == 0)
43 			found = i+1;
44 	}
45 
46 	/* At this time, we don't support modules comiled with -shared */
47 	if (found) {
48 		printk(KERN_WARNING
49 			"Module '%s' contains unexpected .plt/.got sections.\n",
50 			mod->name);
51 		/*  return -ENOEXEC;  */
52 	}
53 
54 	return 0;
55 }
56 
57 /*
58  * apply_relocate_add - perform rela relocations.
59  * @sechdrs - pointer to section headers
60  * @strtab - some sort of start address?
61  * @symindex - symbol index offset or something?
62  * @relsec - address to relocate to?
63  * @module - pointer to module
64  *
65  * Perform rela relocations.
66  */
apply_relocate_add(Elf_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * module)67 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
68 			unsigned int symindex, unsigned int relsec,
69 			struct module *module)
70 {
71 	unsigned int i;
72 	Elf32_Sym *sym;
73 	uint32_t *location;
74 	uint32_t value;
75 	unsigned int nrelocs = sechdrs[relsec].sh_size / sizeof(Elf32_Rela);
76 	Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
77 	Elf32_Word sym_info = sechdrs[relsec].sh_info;
78 	Elf32_Sym *sym_base = (Elf32_Sym *) sechdrs[symindex].sh_addr;
79 	void *loc_base = (void *) sechdrs[sym_info].sh_addr;
80 
81 	DEBUGP("Applying relocations in section %u to section %u base=%p\n",
82 	       relsec, sym_info, loc_base);
83 
84 	for (i = 0; i < nrelocs; i++) {
85 
86 		/* Symbol to relocate */
87 		sym = sym_base + ELF32_R_SYM(rela[i].r_info);
88 
89 		/* Where to make the change */
90 		location = loc_base + rela[i].r_offset;
91 
92 		/* `Everything is relative'. */
93 		value = sym->st_value + rela[i].r_addend;
94 
95 		DEBUGP("%d: value=%08x loc=%p reloc=%d symbol=%s\n",
96 		       i, value, location, ELF32_R_TYPE(rela[i].r_info),
97 		       sym->st_name ?
98 		       &strtab[sym->st_name] : "(anonymous)");
99 
100 		switch (ELF32_R_TYPE(rela[i].r_info)) {
101 		case R_HEXAGON_B22_PCREL: {
102 			int dist = (int)(value - (uint32_t)location);
103 			if ((dist < -0x00800000) ||
104 			    (dist >= 0x00800000)) {
105 				printk(KERN_ERR
106 				       "%s: %s: %08x=%08x-%08x %s\n",
107 				       module->name,
108 				       "R_HEXAGON_B22_PCREL reloc out of range",
109 				       dist, value, (uint32_t)location,
110 				       sym->st_name ?
111 				       &strtab[sym->st_name] : "(anonymous)");
112 				return -ENOEXEC;
113 			}
114 			DEBUGP("B22_PCREL contents: %08X.\n", *location);
115 			*location &= ~0x01ff3fff;
116 			*location |= 0x00003fff & dist;
117 			*location |= 0x01ff0000 & (dist<<2);
118 			DEBUGP("Contents after reloc: %08x\n", *location);
119 			break;
120 		}
121 		case R_HEXAGON_HI16:
122 			value = (value>>16) & 0xffff;
123 			fallthrough;
124 		case R_HEXAGON_LO16:
125 			*location &= ~0x00c03fff;
126 			*location |= value & 0x3fff;
127 			*location |= (value & 0xc000) << 8;
128 			break;
129 		case R_HEXAGON_32:
130 			*location = value;
131 			break;
132 		case R_HEXAGON_32_PCREL:
133 			*location = value - (uint32_t)location;
134 			break;
135 		case R_HEXAGON_PLT_B22_PCREL:
136 		case R_HEXAGON_GOTOFF_LO16:
137 		case R_HEXAGON_GOTOFF_HI16:
138 			printk(KERN_ERR "%s: GOT/PLT relocations unsupported\n",
139 			       module->name);
140 			return -ENOEXEC;
141 		default:
142 			printk(KERN_ERR "%s: unknown relocation: %u\n",
143 			       module->name,
144 			       ELF32_R_TYPE(rela[i].r_info));
145 			return -ENOEXEC;
146 		}
147 	}
148 	return 0;
149 }
150