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 */
27int 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 */
67int 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