xref: /linux/arch/arc/kernel/module.c (revision 75bf465f0bc33e9b776a46d6a1b9b990f5fb7c37)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4  */
5 
6 #include <linux/module.h>
7 #include <linux/moduleloader.h>
8 #include <linux/kernel.h>
9 #include <linux/elf.h>
10 #include <linux/vmalloc.h>
11 #include <linux/slab.h>
12 #include <linux/fs.h>
13 #include <linux/string.h>
14 #include <asm/unwind.h>
15 
arc_write_me(unsigned short * addr,unsigned long value)16 static inline void arc_write_me(unsigned short *addr, unsigned long value)
17 {
18 	*addr = (value & 0xffff0000) >> 16;
19 	*(addr + 1) = (value & 0xffff);
20 }
21 
22 /*
23  * This gets called before relocation loop in generic loader
24  * Make a note of the section index of unwinding section
25  */
module_frob_arch_sections(Elf_Ehdr * hdr,Elf_Shdr * sechdrs,char * secstr,struct module * mod)26 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
27 			      char *secstr, struct module *mod)
28 {
29 #ifdef CONFIG_ARC_DW2_UNWIND
30 	mod->arch.unw_sec_idx = 0;
31 	mod->arch.unw_info = NULL;
32 #endif
33 	mod->arch.secstr = secstr;
34 	return 0;
35 }
36 
module_arch_cleanup(struct module * mod)37 void module_arch_cleanup(struct module *mod)
38 {
39 #ifdef CONFIG_ARC_DW2_UNWIND
40 	if (mod->arch.unw_info)
41 		unwind_remove_table(mod->arch.unw_info, 0);
42 #endif
43 }
44 
apply_relocate_add(Elf32_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * module)45 int apply_relocate_add(Elf32_Shdr *sechdrs,
46 		       const char *strtab,
47 		       unsigned int symindex,	/* sec index for sym tbl */
48 		       unsigned int relsec,	/* sec index for relo sec */
49 		       struct module *module)
50 {
51 	int i, n, relo_type;
52 	Elf32_Rela *rel_entry = (void *)sechdrs[relsec].sh_addr;
53 	Elf32_Sym *sym_entry, *sym_sec;
54 	Elf32_Addr relocation, location, tgt_addr;
55 	unsigned int tgtsec;
56 
57 	/*
58 	 * @relsec has relocations e.g. .rela.init.text
59 	 * @tgtsec is section to patch e.g. .init.text
60 	 */
61 	tgtsec = sechdrs[relsec].sh_info;
62 	tgt_addr = sechdrs[tgtsec].sh_addr;
63 	sym_sec = (Elf32_Sym *) sechdrs[symindex].sh_addr;
64 	n = sechdrs[relsec].sh_size / sizeof(*rel_entry);
65 
66 	pr_debug("\nSection to fixup %s @%x\n",
67 		 module->arch.secstr + sechdrs[tgtsec].sh_name, tgt_addr);
68 	pr_debug("=========================================================\n");
69 	pr_debug("r_off\tr_add\tst_value ADDRESS  VALUE\n");
70 	pr_debug("=========================================================\n");
71 
72 	/* Loop thru entries in relocation section */
73 	for (i = 0; i < n; i++) {
74 		const char *s;
75 
76 		/* This is where to make the change */
77 		location = tgt_addr + rel_entry[i].r_offset;
78 
79 		/* This is the symbol it is referring to.  Note that all
80 		   undefined symbols have been resolved.  */
81 		sym_entry = sym_sec + ELF32_R_SYM(rel_entry[i].r_info);
82 
83 		relocation = sym_entry->st_value + rel_entry[i].r_addend;
84 
85 		if (sym_entry->st_name == 0 && ELF_ST_TYPE (sym_entry->st_info) == STT_SECTION) {
86 			s = module->arch.secstr + sechdrs[sym_entry->st_shndx].sh_name;
87 		} else {
88 			s = strtab + sym_entry->st_name;
89 		}
90 
91 		pr_debug("   %x\t%x\t%x %x %x [%s]\n",
92 			 rel_entry[i].r_offset, rel_entry[i].r_addend,
93 			 sym_entry->st_value, location, relocation, s);
94 
95 		/* This assumes modules are built with -mlong-calls
96 		 * so any branches/jumps are absolute 32 bit jmps
97 		 * global data access again is abs 32 bit.
98 		 * Both of these are handled by same relocation type
99 		 */
100 		relo_type = ELF32_R_TYPE(rel_entry[i].r_info);
101 
102 		if (likely(R_ARC_32_ME == relo_type))	/* ME ( S + A ) */
103 			arc_write_me((unsigned short *)location, relocation);
104 		else if (R_ARC_32 == relo_type)		/* ( S + A ) */
105 			*((Elf32_Addr *) location) = relocation;
106 		else if (R_ARC_32_PCREL == relo_type)	/* ( S + A ) - PDATA ) */
107 			*((Elf32_Addr *) location) = relocation - location;
108 		else
109 			goto relo_err;
110 
111 	}
112 
113 #ifdef CONFIG_ARC_DW2_UNWIND
114 	if (strcmp(module->arch.secstr+sechdrs[tgtsec].sh_name, ".eh_frame") == 0)
115 		module->arch.unw_sec_idx = tgtsec;
116 #endif
117 
118 	return 0;
119 
120 relo_err:
121 	pr_err("%s: unknown relocation: %u\n",
122 		module->name, ELF32_R_TYPE(rel_entry[i].r_info));
123 	return -ENOEXEC;
124 
125 }
126 
127 /* Just before lift off: After sections have been relocated, we add the
128  * dwarf section to unwinder table pool
129  * This couldn't be done in module_frob_arch_sections() because
130  * relocations had not been applied by then
131  */
module_finalize(const Elf32_Ehdr * hdr,const Elf_Shdr * sechdrs,struct module * mod)132 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
133 		    struct module *mod)
134 {
135 #ifdef CONFIG_ARC_DW2_UNWIND
136 	void *unw;
137 	int unwsec = mod->arch.unw_sec_idx;
138 
139 	if (unwsec) {
140 		unw = unwind_add_table(mod, (void *)sechdrs[unwsec].sh_addr,
141 				       sechdrs[unwsec].sh_size);
142 		mod->arch.unw_info = unw;
143 	}
144 #endif
145 	return 0;
146 }
147