module.c

  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}