1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #if !defined(__LP64__) && __mips_isa_rev >= 5 30 #include <sys/prctl.h> 31 #endif 32 33 #include "linker.h" 34 #include "linker_debug.h" 35 #include "linker_globals.h" 36 #include "linker_phdr.h" 37 #include "linker_relocs.h" 38 #include "linker_reloc_iterators.h" 39 #include "linker_sleb128.h" 40 #include "linker_soinfo.h" 41 42 template bool soinfo::relocate<plain_reloc_iterator>(const VersionTracker& version_tracker, 43 plain_reloc_iterator&& rel_iterator, 44 const soinfo_list_t& global_group, 45 const soinfo_list_t& local_group); 46 47 template bool soinfo::relocate<packed_reloc_iterator<sleb128_decoder>>( 48 const VersionTracker& version_tracker, 49 packed_reloc_iterator<sleb128_decoder>&& rel_iterator, 50 const soinfo_list_t& global_group, 51 const soinfo_list_t& local_group); 52 53 template <typename ElfRelIteratorT> 54 bool soinfo::relocate(const VersionTracker& version_tracker, 55 ElfRelIteratorT&& rel_iterator, 56 const soinfo_list_t& global_group, 57 const soinfo_list_t& local_group) { 58 for (size_t idx = 0; rel_iterator.has_next(); ++idx) { 59 const auto rel = rel_iterator.next(); 60 61 if (rel == nullptr) { 62 return false; 63 } 64 65 ElfW(Word) type = ELFW(R_TYPE)(rel->r_info); 66 ElfW(Word) sym = ELFW(R_SYM)(rel->r_info); 67 68 ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + load_bias); 69 ElfW(Addr) sym_addr = 0; 70 const char* sym_name = nullptr; 71 72 DEBUG("Processing \"%s\" relocation at index %zd", get_realpath(), idx); 73 if (type == R_GENERIC_NONE) { 74 continue; 75 } 76 77 const ElfW(Sym)* s = nullptr; 78 soinfo* lsi = nullptr; 79 80 if (sym != 0) { 81 sym_name = get_string(symtab_[sym].st_name); 82 const version_info* vi = nullptr; 83 84 if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) { 85 return false; 86 } 87 88 if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) { 89 return false; 90 } 91 92 if (s == nullptr) { 93 // mips does not support relocation with weak-undefined symbols 94 DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", 95 sym_name, get_realpath()); 96 return false; 97 } else { 98 // We got a definition. 99 sym_addr = lsi->resolve_symbol_address(s); 100 } 101 count_relocation(kRelocSymbol); 102 } 103 104 switch (type) { 105 case R_MIPS_REL32: 106 #if defined(__LP64__) 107 // MIPS Elf64_Rel entries contain compound relocations 108 // We only handle the R_MIPS_NONE|R_MIPS_64|R_MIPS_REL32 case 109 if (ELF64_R_TYPE2(rel->r_info) != R_MIPS_64 || 110 ELF64_R_TYPE3(rel->r_info) != R_MIPS_NONE) { 111 DL_ERR("Unexpected compound relocation type:%d type2:%d type3:%d @ %p (%zu)", 112 type, static_cast<unsigned>(ELF64_R_TYPE2(rel->r_info)), 113 static_cast<unsigned>(ELF64_R_TYPE3(rel->r_info)), rel, idx); 114 return false; 115 } 116 #endif 117 count_relocation(s == nullptr ? kRelocAbsolute : kRelocRelative); 118 MARK(rel->r_offset); 119 TRACE_TYPE(RELO, "RELO REL32 %08zx <- %08zx %s", static_cast<size_t>(reloc), 120 static_cast<size_t>(sym_addr), sym_name ? sym_name : "*SECTIONHDR*"); 121 if (s != nullptr) { 122 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 123 } else { 124 *reinterpret_cast<ElfW(Addr)*>(reloc) += load_bias; 125 } 126 break; 127 default: 128 DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx); 129 return false; 130 } 131 } 132 return true; 133 } 134 135 bool soinfo::mips_relocate_got(const VersionTracker& version_tracker, 136 const soinfo_list_t& global_group, 137 const soinfo_list_t& local_group) { 138 ElfW(Addr)** got = plt_got_; 139 if (got == nullptr) { 140 return true; 141 } 142 143 // got[0] is the address of the lazy resolver function. 144 // got[1] may be used for a GNU extension. 145 // Set it to a recognizable address in case someone calls it (should be _rtld_bind_start). 146 // FIXME: maybe this should be in a separate routine? 147 if ((flags_ & FLAG_LINKER) == 0) { 148 size_t g = 0; 149 got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadbeef); 150 if (reinterpret_cast<intptr_t>(got[g]) < 0) { 151 got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadfeed); 152 } 153 // Relocate the local GOT entries. 154 for (; g < mips_local_gotno_; g++) { 155 got[g] = reinterpret_cast<ElfW(Addr)*>(reinterpret_cast<uintptr_t>(got[g]) + load_bias); 156 } 157 } 158 159 // Now for the global GOT entries... 160 got = plt_got_ + mips_local_gotno_; 161 for (ElfW(Word) sym = mips_gotsym_; sym < mips_symtabno_; sym++, got++) { 162 // This is an undefined reference... try to locate it. 163 const ElfW(Sym)* local_sym = symtab_ + sym; 164 const char* sym_name = get_string(local_sym->st_name); 165 soinfo* lsi = nullptr; 166 const ElfW(Sym)* s = nullptr; 167 168 ElfW(Word) st_visibility = (local_sym->st_other & 0x3); 169 170 if (st_visibility == STV_DEFAULT) { 171 const version_info* vi = nullptr; 172 173 if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) { 174 return false; 175 } 176 177 if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) { 178 return false; 179 } 180 } else if (st_visibility == STV_PROTECTED) { 181 if (local_sym->st_value == 0) { 182 DL_ERR("%s: invalid symbol \"%s\" (PROTECTED/UNDEFINED) ", 183 get_realpath(), sym_name); 184 return false; 185 } 186 s = local_sym; 187 lsi = this; 188 } else { 189 DL_ERR("%s: invalid symbol \"%s\" visibility: 0x%x", 190 get_realpath(), sym_name, st_visibility); 191 return false; 192 } 193 194 if (s == nullptr) { 195 // We only allow an undefined symbol if this is a weak reference. 196 if (ELF_ST_BIND(local_sym->st_info) != STB_WEAK) { 197 DL_ERR("%s: cannot locate \"%s\"...", get_realpath(), sym_name); 198 return false; 199 } 200 *got = 0; 201 } else { 202 // FIXME: is this sufficient? 203 // For reference see NetBSD link loader 204 // http://cvsweb.netbsd.org/bsdweb.cgi/src/libexec/ld.elf_so/arch/mips/mips_reloc.c?rev=1.53&content-type=text/x-cvsweb-markup 205 *got = reinterpret_cast<ElfW(Addr)*>(lsi->resolve_symbol_address(s)); 206 } 207 } 208 return true; 209 } 210 211 #if !defined(__LP64__) 212 213 // Checks for mips32's various floating point abis. 214 // (Mips64 Android has a single floating point abi and doesn't need any checks) 215 216 // Linux kernel has declarations similar to the following 217 // in <linux>/arch/mips/include/asm/elf.h, 218 // but that non-uapi internal header file will never be imported 219 // into bionic's kernel headers. 220 221 #define PT_MIPS_ABIFLAGS 0x70000003 // is .MIPS.abiflags segment 222 223 struct mips_elf_abiflags_v0 { 224 uint16_t version; // version of this structure 225 uint8_t isa_level, isa_rev, gpr_size, cpr1_size, cpr2_size; 226 uint8_t fp_abi; // mips32 ABI variants for floating point 227 uint32_t isa_ext, ases, flags1, flags2; 228 }; 229 230 // Bits of flags1: 231 #define MIPS_AFL_FLAGS1_ODDSPREG 1 // Uses odd-numbered single-prec fp regs 232 233 // Some values of fp_abi: via compiler flag: 234 #define MIPS_ABI_FP_DOUBLE 1 // -mdouble-float 235 #define MIPS_ABI_FP_XX 5 // -mfpxx 236 #define MIPS_ABI_FP_64A 7 // -mips32r* -mfp64 -mno-odd-spreg 237 238 #if __mips_isa_rev >= 5 239 static bool mips_fre_mode_on = false; // have set FRE=1 mode for process 240 #endif 241 242 bool soinfo::mips_check_and_adjust_fp_modes() { 243 mips_elf_abiflags_v0* abiflags = nullptr; 244 int mips_fpabi; 245 246 // Find soinfo's optional .MIPS.abiflags segment 247 for (size_t i = 0; i<phnum; ++i) { 248 const ElfW(Phdr)& ph = phdr[i]; 249 if (ph.p_type == PT_MIPS_ABIFLAGS) { 250 if (ph.p_filesz < sizeof (mips_elf_abiflags_v0)) { 251 DL_ERR("Corrupt PT_MIPS_ABIFLAGS header found \"%s\"", get_realpath()); 252 return false; 253 } 254 abiflags = reinterpret_cast<mips_elf_abiflags_v0*>(ph.p_vaddr + load_bias); 255 break; 256 } 257 } 258 259 // FP ABI-variant compatibility checks for MIPS o32 ABI 260 if (abiflags == nullptr) { 261 // Old compilers lack the new abiflags section. 262 // These compilers used -mfp32 -mdouble-float -modd-spreg defaults, 263 // ie FP32 aka DOUBLE, using odd-numbered single-prec regs 264 mips_fpabi = MIPS_ABI_FP_DOUBLE; 265 } else { 266 mips_fpabi = abiflags->fp_abi; 267 if ( (abiflags->flags1 & MIPS_AFL_FLAGS1_ODDSPREG) 268 && (mips_fpabi == MIPS_ABI_FP_XX || 269 mips_fpabi == MIPS_ABI_FP_64A ) ) { 270 // Android supports fewer cases than Linux 271 DL_ERR("Unsupported odd-single-prec FloatPt reg uses in \"%s\"", 272 get_realpath()); 273 return false; 274 } 275 } 276 if (!(mips_fpabi == MIPS_ABI_FP_DOUBLE || 277 #if __mips_isa_rev >= 5 278 mips_fpabi == MIPS_ABI_FP_64A || 279 #endif 280 mips_fpabi == MIPS_ABI_FP_XX )) { 281 DL_ERR("Unsupported MIPS32 FloatPt ABI %d found in \"%s\"", 282 mips_fpabi, get_realpath()); 283 return false; 284 } 285 286 #if __mips_isa_rev >= 5 287 // Adjust process's FR Emulation mode, if needed 288 // 289 // On Mips R5 & R6, Android runs continuously in FR=1 64bit-fpreg mode. 290 // NDK mips32 apps compiled with old compilers generate FP32 code 291 // which expects FR=0 32-bit fp registers. 292 // NDK mips32 apps compiled with newer compilers generate modeless 293 // FPXX code which runs on both FR=0 and FR=1 modes. 294 // Android itself is compiled in FP64A which requires FR=1 mode. 295 // FP32, FPXX, and FP64A all interlink okay, without dynamic FR mode 296 // changes during calls. For details, see 297 // http://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking 298 // Processes containing FR32 FR=0 code are run via kernel software assist, 299 // which maps all odd-numbered single-precision reg refs onto the 300 // upper half of the paired even-numbered double-precision reg. 301 // FRE=1 triggers traps to the kernel's emulator on every single-precision 302 // fp op (for both odd and even-numbered registers). 303 // Turning on FRE=1 traps is done at most once per process, simultanously 304 // for all threads of that process, when dlopen discovers FP32 code. 305 // The kernel repacks threads' registers when FRE mode is turn on or off. 306 // These asynchronous adjustments are wrong if any thread was executing 307 // FPXX code using odd-numbered single-precision regs. 308 // Current Android compilers default to the -mno-oddspreg option, 309 // and this requirement is checked by Android's dlopen. 310 // So FRE can always be safely turned on for FP32, anytime. 311 // Deferred enhancement: Allow loading of odd-spreg FPXX modules. 312 313 if (mips_fpabi == MIPS_ABI_FP_DOUBLE && !mips_fre_mode_on) { 314 // Turn on FRE mode, which emulates mode-sensitive FR=0 code on FR=1 315 // register files, by trapping to kernel on refs to single-precision regs 316 if (prctl(PR_SET_FP_MODE, PR_FP_MODE_FR|PR_FP_MODE_FRE)) { 317 DL_ERR("Kernel or cpu failed to set FRE mode required for running \"%s\"", 318 get_realpath()); 319 return false; 320 } 321 DL_WARN("Using FRE=1 mode to run \"%s\"", get_realpath()); 322 mips_fre_mode_on = true; // Avoid future redundant mode-switch calls 323 // FRE mode is never turned back off. 324 // Deferred enhancement: 325 // Reset FRE mode when dlclose() removes all FP32 modules 326 } 327 #else 328 // Android runs continuously in FR=0 32bit-fpreg mode. 329 #endif // __mips_isa_rev 330 return true; 331 } 332 333 #endif // __LP64___ 334
