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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ART_RUNTIME_ELF_UTILS_H_
     18 #define ART_RUNTIME_ELF_UTILS_H_
     19 
     20 #include <sys/cdefs.h>
     21 
     22 #include <android-base/logging.h>
     23 
     24 // Explicitly include our own elf.h to avoid Linux and other dependencies.
     25 #include "./elf.h"
     26 
     27 namespace art {
     28 
     29 // Architecture dependent flags for the ELF header.
     30 #define EF_ARM_EABI_VER5 0x05000000
     31 #define EF_MIPS_ABI_O32 0x00001000
     32 #define EF_MIPS_ARCH_32R2 0x70000000
     33 #define EF_MIPS_ARCH_32R6 0x90000000
     34 #define EF_MIPS_ARCH_64R6 0xa0000000
     35 
     36 #define EI_ABIVERSION 8
     37 #define EM_ARM 40
     38 #define EF_MIPS_NOREORDER 1
     39 #define EF_MIPS_PIC 2
     40 #define EF_MIPS_CPIC 4
     41 #define STV_DEFAULT 0
     42 
     43 #define EM_AARCH64 183
     44 
     45 #define DT_BIND_NOW 24
     46 #define DT_INIT_ARRAY 25
     47 #define DT_FINI_ARRAY 26
     48 #define DT_INIT_ARRAYSZ 27
     49 #define DT_FINI_ARRAYSZ 28
     50 #define DT_RUNPATH 29
     51 #define DT_FLAGS 30
     52 
     53 /* MIPS dependent d_tag field for Elf32_Dyn.  */
     54 #define DT_MIPS_RLD_VERSION  0x70000001 /* Runtime Linker Interface ID */
     55 #define DT_MIPS_TIME_STAMP   0x70000002 /* Timestamp */
     56 #define DT_MIPS_ICHECKSUM    0x70000003 /* Cksum of ext. str. and com. sizes */
     57 #define DT_MIPS_IVERSION     0x70000004 /* Version string (string tbl index) */
     58 #define DT_MIPS_FLAGS        0x70000005 /* Flags */
     59 #define DT_MIPS_BASE_ADDRESS 0x70000006 /* Segment base address */
     60 #define DT_MIPS_CONFLICT     0x70000008 /* Adr of .conflict section */
     61 #define DT_MIPS_LIBLIST      0x70000009 /* Address of .liblist section */
     62 #define DT_MIPS_LOCAL_GOTNO  0x7000000a /* Number of local .GOT entries */
     63 #define DT_MIPS_CONFLICTNO   0x7000000b /* Number of .conflict entries */
     64 #define DT_MIPS_LIBLISTNO    0x70000010 /* Number of .liblist entries */
     65 #define DT_MIPS_SYMTABNO     0x70000011 /* Number of .dynsym entries */
     66 #define DT_MIPS_UNREFEXTNO   0x70000012 /* First external DYNSYM */
     67 #define DT_MIPS_GOTSYM       0x70000013 /* First GOT entry in .dynsym */
     68 #define DT_MIPS_HIPAGENO     0x70000014 /* Number of GOT page table entries */
     69 #define DT_MIPS_RLD_MAP      0x70000016 /* Address of debug map pointer */
     70 
     71 // Patching section type
     72 #define SHT_OAT_PATCH        SHT_LOUSER
     73 
     74 static inline void SetBindingAndType(Elf32_Sym* sym, unsigned char b, unsigned char t) {
     75   sym->st_info = (b << 4) + (t & 0x0f);
     76 }
     77 
     78 static inline bool IsDynamicSectionPointer(Elf32_Word d_tag, Elf32_Word e_machine) {
     79   switch (d_tag) {
     80     // case 1: well known d_tag values that imply Elf32_Dyn.d_un contains an address in d_ptr
     81     case DT_PLTGOT:
     82     case DT_HASH:
     83     case DT_STRTAB:
     84     case DT_SYMTAB:
     85     case DT_RELA:
     86     case DT_INIT:
     87     case DT_FINI:
     88     case DT_REL:
     89     case DT_DEBUG:
     90     case DT_JMPREL: {
     91       return true;
     92     }
     93     // d_val or ignored values
     94     case DT_NULL:
     95     case DT_NEEDED:
     96     case DT_PLTRELSZ:
     97     case DT_RELASZ:
     98     case DT_RELAENT:
     99     case DT_STRSZ:
    100     case DT_SYMENT:
    101     case DT_SONAME:
    102     case DT_RPATH:
    103     case DT_SYMBOLIC:
    104     case DT_RELSZ:
    105     case DT_RELENT:
    106     case DT_PLTREL:
    107     case DT_TEXTREL:
    108     case DT_BIND_NOW:
    109     case DT_INIT_ARRAYSZ:
    110     case DT_FINI_ARRAYSZ:
    111     case DT_RUNPATH:
    112     case DT_FLAGS: {
    113       return false;
    114     }
    115     // boundary values that should not be used
    116     case DT_ENCODING:
    117     case DT_LOOS:
    118     case DT_HIOS:
    119     case DT_LOPROC:
    120     case DT_HIPROC: {
    121       LOG(FATAL) << "Illegal d_tag value 0x" << std::hex << d_tag;
    122       return false;
    123     }
    124     default: {
    125       // case 2: "regular" DT_* ranges where even d_tag values imply an address in d_ptr
    126       if ((DT_ENCODING  < d_tag && d_tag < DT_LOOS)
    127           || (DT_LOOS   < d_tag && d_tag < DT_HIOS)
    128           || (DT_LOPROC < d_tag && d_tag < DT_HIPROC)) {
    129         // Special case for MIPS which breaks the regular rules between DT_LOPROC and DT_HIPROC
    130         if (e_machine == EM_MIPS) {
    131           switch (d_tag) {
    132             case DT_MIPS_RLD_VERSION:
    133             case DT_MIPS_TIME_STAMP:
    134             case DT_MIPS_ICHECKSUM:
    135             case DT_MIPS_IVERSION:
    136             case DT_MIPS_FLAGS:
    137             case DT_MIPS_LOCAL_GOTNO:
    138             case DT_MIPS_CONFLICTNO:
    139             case DT_MIPS_LIBLISTNO:
    140             case DT_MIPS_SYMTABNO:
    141             case DT_MIPS_UNREFEXTNO:
    142             case DT_MIPS_GOTSYM:
    143             case DT_MIPS_HIPAGENO: {
    144               return false;
    145             }
    146             case DT_MIPS_BASE_ADDRESS:
    147             case DT_MIPS_CONFLICT:
    148             case DT_MIPS_LIBLIST:
    149             case DT_MIPS_RLD_MAP: {
    150               return true;
    151             }
    152             default: {
    153               LOG(FATAL) << "Unknown MIPS d_tag value 0x" << std::hex << d_tag;
    154               return false;
    155             }
    156           }
    157         } else if ((d_tag % 2) == 0) {
    158           return true;
    159         } else {
    160           return false;
    161         }
    162       } else {
    163         LOG(FATAL) << "Unknown d_tag value 0x" << std::hex << d_tag;
    164         return false;
    165       }
    166     }
    167   }
    168 }
    169 
    170 }  // namespace art
    171 
    172 #endif  // ART_RUNTIME_ELF_UTILS_H_
    173