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 */ 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 */ 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