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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | /* * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com) * * Licensed under the LGPL v2.1 or later, see the file COPYING.LIB in this tarball. */ #include "elf.h" /* * Define this if the system uses RELOCA. */ #define ELF_USES_RELOCA /* * Dynamic Linking ABI for ARCompact ISA * * PLT * -------------------------------- * | ld r11, [pcl, off-to-GOT[1] | 0 (20 bytes) * | | 4 * plt0 | ld r10, [pcl, off-to-GOT[2] | 8 * | | 12 * | j [r10] | 16 * -------------------------------- * | Base address of GOT | 20 * -------------------------------- * | ld r12, [pcl, off-to-GOT[3] | 24 (12 bytes each) * plt1 | | * | j_s.d [r12] | 32 * | mov_s r12, pcl | 34 * -------------------------------- * | | 36 * ~ ~ * ~ ~ * | | * -------------------------------- * * GOT * -------------- * | [0] | * -------------- * | [1] | Module info - setup by ldso * -------------- * | [2] | resolver entry point * -------------- * | [3] | * | ... | Runtime address for function symbols * | [f] | * -------------- * | [f+1] | * | ... | Runtime address for data symbols * | [last] | * -------------- */ /* * Initialization sequence for a GOT. * Caller elf_resolve() seeds @GOT_BASE from DT_PLTGOT - which essentially is * pointer to first PLT entry. The actual GOT base is 5th word in PLT * */ #define INIT_GOT(GOT_BASE,MODULE) \ do { \ unsigned long *__plt_base = (unsigned long *)GOT_BASE; \ GOT_BASE = (unsigned long *)(__plt_base[5] + \ (unsigned long)MODULE->loadaddr); \ GOT_BASE[1] = (unsigned long) MODULE; \ GOT_BASE[2] = (unsigned long) _dl_linux_resolve; \ } while(0) /* Here we define the magic numbers that this dynamic loader should accept */ #ifdef __A7__ #define MAGIC1 EM_ARCOMPACT #define ELF_TARGET "ARCompact" /* For error messages */ #elif defined(__HS__) #define MAGIC1 EM_ARCV2 #define ELF_TARGET "ARCv2" /* For error messages */ #elif defined(__ARC64_ARCH32__) #define MAGIC1 EM_ARCV3_32 #define ELF_TARGET "ARCv3_32" /* For error messages */ #endif #undef MAGIC2 struct elf_resolve; extern unsigned long _dl_linux_resolver(struct elf_resolve * tpnt, unsigned int plt_pc); extern unsigned __udivmodsi4(unsigned, unsigned) attribute_hidden; #ifdef __A7__ /* using "C" causes an indirection via __umodsi3 -> __udivmodsi4 */ #define do_rem(result, n, base) ((result) = \ \ __builtin_constant_p (base) ? (n) % (unsigned) (base) : \ __extension__ ({ \ register unsigned r1 __asm__ ("r1") = (base); \ \ __asm__("bl.d @__udivmodsi4` mov r0,%1" \ : "=r" (r1) \ : "r" (n), "r" (r1) \ : "r0", "r2", "r3", "r4", "lp_count", "blink", "cc"); \ \ r1; \ }) \ ) #elif defined(__HS__) /* ARCv2 has hardware assisted divide/mod */ #define do_rem(result, n, base) ((result) = (n) % (unsigned) (base)) #endif /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or TLS variable so PLT entries should not be allowed to define the value. ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one of the main executable's symbols, as for a COPY reloc. */ #define elf_machine_type_class(type) \ ((((type) == R_ARC_JMP_SLOT || (type) == R_ARC_TLS_DTPMOD || \ (type) == R_ARC_TLS_DTPOFF || (type) == R_ARC_TLS_TPOFF) \ * ELF_RTYPE_CLASS_PLT) \ | (((type) == R_ARC_COPY) * ELF_RTYPE_CLASS_COPY)) /* * Get build time address of .dynamic as setup in GOT[0] * This is called very early in _dl_start() so it has not been relocated to * runtime value */ static __always_inline Elf32_Addr elf_machine_dynamic(void) { extern const Elf32_Addr _GLOBAL_OFFSET_TABLE_[] attribute_hidden; return _GLOBAL_OFFSET_TABLE_[0]; } /* Return the run-time load address of the shared object. */ static __always_inline Elf32_Addr elf_machine_load_address(void) { /* To find the loadaddr we subtract the runtime addr of a non-local symbol * say _DYNAMIC from it's build-time addr. * N.B., gotpc loads get optimized by the linker if it finds the symbol * is resolved locally. * A more robust - and efficient - solution would be to use a symbol * set by the linker. To make it actually save space, we'd have to * suppress the unwanted text relocation in the linked dso, though. * (I.e. in ldso.so.*, though it's just another dso as far as bfd/ld * are concerned.) */ Elf32_Addr addr, tmp; __asm__ ( "ld %1, [pcl, _dl_start@gotpc] ;build addr of _DYNAMIC" "\n" "add %0, pcl, _dl_start@pcl ;runtime addr of _DYNAMIC" "\n" "sub %0, %0, %1 ;delta" "\n" : "=&r" (addr), "=r"(tmp) ); return addr; } static __always_inline void elf_machine_relative (Elf32_Addr load_off, const Elf32_Addr rel_addr, Elf32_Word relative_count) { Elf32_Rela * rpnt = (void *) rel_addr; --rpnt; do { Elf32_Addr *const reloc_addr = (void *) (load_off + (++rpnt)->r_offset); *reloc_addr += load_off; } while (--relative_count); } |