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| 1 | /* Machine-dependent ELF dynamic relocation inline functions. Stub version. |
|---|---|
| 2 | Copyright (C) 1995-2022 Free Software Foundation, Inc. |
| 3 | This file is part of the GNU C Library. |
| 4 | |
| 5 | The GNU C Library is free software; you can redistribute it and/or |
| 6 | modify it under the terms of the GNU Lesser General Public |
| 7 | License as published by the Free Software Foundation; either |
| 8 | version 2.1 of the License, or (at your option) any later version. |
| 9 | |
| 10 | The GNU C Library is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | Lesser General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU Lesser General Public |
| 16 | License along with the GNU C Library; if not, see |
| 17 | <https://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #define ELF_MACHINE_NAME "stub" |
| 20 | |
| 21 | #include <string.h> |
| 22 | #include <link.h> |
| 23 | #include <dl-static-tls.h> |
| 24 | #include <dl-machine-rel.h> |
| 25 | |
| 26 | |
| 27 | /* Return nonzero iff ELF header is compatible with the running host. */ |
| 28 | static inline int |
| 29 | elf_machine_matches_host (const Elf32_Ehdr *ehdr) |
| 30 | { |
| 31 | switch (ehdr->e_machine) |
| 32 | { |
| 33 | default: |
| 34 | return 0; |
| 35 | } |
| 36 | } |
| 37 | |
| 38 | |
| 39 | /* Return the link-time address of _DYNAMIC. */ |
| 40 | static inline Elf32_Addr |
| 41 | elf_machine_dynamic (void) |
| 42 | { |
| 43 | #error "Damn, no _DYNAMIC" |
| 44 | } |
| 45 | |
| 46 | |
| 47 | /* Return the run-time load address of the shared object. */ |
| 48 | static inline Elf32_Addr |
| 49 | elf_machine_load_address (void) |
| 50 | { |
| 51 | #error "Where am I?" |
| 52 | } |
| 53 | |
| 54 | /* Fixup a PLT entry to bounce directly to the function at VALUE. */ |
| 55 | |
| 56 | static inline ElfW(Addr) |
| 57 | elf_machine_fixup_plt (struct link_map *map, lookup_t t, |
| 58 | const ElfW(Sym) *refsym, const ElfW(Sym) *sym, |
| 59 | const ElfW(Rel) *reloc, |
| 60 | ElfW(Addr) *reloc_addr, ElfW(Addr) value) |
| 61 | { |
| 62 | return *reloc_addr = value; |
| 63 | } |
| 64 | |
| 65 | /* Perform the relocation specified by RELOC and SYM (which is fully resolved). |
| 66 | LOADADDR is the load address of the object; INFO is an array indexed |
| 67 | by DT_* of the .dynamic section info. */ |
| 68 | |
| 69 | auto inline void |
| 70 | __attribute__ ((always_inline)) |
| 71 | elf_machine_rel (Elf32_Addr loadaddr, Elf32_Dyn *info[DT_NUM], |
| 72 | const Elf32_Rel *reloc, const Elf32_Sym *sym, |
| 73 | Elf32_Addr (*resolve) (const Elf32_Sym **ref, |
| 74 | Elf32_Addr reloc_addr, |
| 75 | int noplt)) |
| 76 | { |
| 77 | Elf32_Addr *const reloc_addr = (Elf32_Addr *) reloc->r_offset; |
| 78 | Elf32_Addr loadbase; |
| 79 | |
| 80 | switch (ELF32_R_TYPE (reloc->r_info)) |
| 81 | { |
| 82 | case R_MACHINE_COPY: |
| 83 | loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0); |
| 84 | memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size); |
| 85 | break; |
| 86 | default: |
| 87 | _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 0); |
| 88 | break; |
| 89 | } |
| 90 | } |
| 91 | |
| 92 | |
| 93 | auto inline Elf32_Addr |
| 94 | __attribute__ ((always_inline)) |
| 95 | elf_machine_rela (Elf32_Addr loadaddr, Elf32_Dyn *info[DT_NUM], |
| 96 | const Elf32_Rel *reloc, const Elf32_Sym *sym, |
| 97 | Elf32_Addr (*resolve) (const Elf32_Sym **ref, |
| 98 | Elf32_Addr reloc_addr, |
| 99 | int noplt)) |
| 100 | { |
| 101 | _dl_signal_error (0, "Elf32_Rela relocation requested -- unused on " |
| 102 | NULL, ELF_MACHINE_NAME); |
| 103 | } |
| 104 | |
| 105 | |
| 106 | /* Set up the loaded object described by L so its unrelocated PLT |
| 107 | entries will jump to the on-demand fixup code in dl-runtime.c. */ |
| 108 | |
| 109 | static inline int |
| 110 | elf_machine_runtime_setup (struct link_map *l, int lazy) |
| 111 | { |
| 112 | extern void _dl_runtime_resolve (Elf32_Word); |
| 113 | |
| 114 | if (lazy) |
| 115 | { |
| 116 | /* The GOT entries for functions in the PLT have not yet been filled |
| 117 | in. Their initial contents will arrange when called to push an |
| 118 | offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1], |
| 119 | and then jump to _GLOBAL_OFFSET_TABLE[2]. */ |
| 120 | Elf32_Addr *got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]); |
| 121 | got[1] = (Elf32_Addr) l; /* Identify this shared object. */ |
| 122 | |
| 123 | /* This function will get called to fix up the GOT entry indicated by |
| 124 | the offset on the stack, and then jump to the resolved address. */ |
| 125 | got[2] = (Elf32_Addr) &_dl_runtime_resolve; |
| 126 | } |
| 127 | |
| 128 | return lazy; |
| 129 | } |
| 130 | |
| 131 | |
| 132 | /* Initial entry point code for the dynamic linker. |
| 133 | The C function `_dl_start' is the real entry point; |
| 134 | its return value is the user program's entry point. */ |
| 135 | |
| 136 | #define RTLD_START #error need some startup code |
| 137 |
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