When there is no section header in an executable or shared library, we
reconstruct dynamic symbol table from the PT_DYNAMIC segment, which
contains DT_HASH/DT_GNU_HASH/DT_MIPS_XHASH, DT_STRTAB, DT_SYMTAB,
DT_STRSZ, and DT_SYMENT entries, to improve nm and objdump. For DT_HASH,
the number of dynamic symbol table entries equals the number of chains.
For DT_GNU_HASH/DT_MIPS_XHASH, only defined symbols with non-STB_LOCAL
indings are in hash table. Since DT_GNU_HASH/DT_MIPS_XHASH place all
symbols with STB_LOCAL binding before symbols with other bindings and
all undefined symbols defined ones in dynamic symbol table, the highest
symbol index in DT_GNU_HASH/DT_MIPS_XHASH is the highest dynamic symbol
table index. We can also get symbol version from DT_VERSYM, DT_VERDEF
and DT_VERNEED entries.
dt_symtab, dt_versym, dt_verdef, dt_verneed, dt_symtab_count,
dt_verdef_count, dt_verneed_count and dt_strtab are added to
elf_obj_tdata to store dynamic symbol table information.
PR ld/25617
* elf-bfd.h (elf_obj_tdata): Add dt_symtab, dt_verdef, dt_verneed,
dt_symtab_count, dt_verdef_count, dt_verneed_count and dt_strtab.
(elf_use_dt_symtab_p): New.
(_bfd_elf_get_dynamic_symbols): Likewise.
(_bfd_elf_get_section_from_dynamic_symbol): Likewise.
* elf.c (bfd_elf_get_elf_syms): Use dynamic symbol table if
neeeded.
(_bfd_elf_get_dynamic_symtab_upper_bound): Likewise.
(_bfd_elf_slurp_version_tables): Likewise.
(offset_from_vma): New function.
(get_hash_table_data): Likewise.
(_bfd_elf_get_dynamic_symbols): Likewise.
(_bfd_elf_get_section_from_dynamic_symbol): Likewise.
(_bfd_elf_get_symbol_version_name): Likewise.
* elfcode.h (elf_object_p): Call _bfd_elf_get_dynamic_symbols
to reconstruct dynamic symbol table from PT_DYNAMIC segment if
there is no section header.
(elf_slurp_symbol_table): Use dynamic symbol table if neeeded.
Don't free isymbuf when dynamic symbol table is used.
* elflink.c (elf_link_is_defined_archive_symbol): Return wrong
format error when dynamic symbol table is used.
(elf_link_add_object_symbols): Likewise.
BFD is an object file library. It permits applications to use the
same routines to process object files regardless of their format.
BFD is used by the GNU debugger, assembler, linker, and the binary
utilities.
The documentation on using BFD is scanty and may be occasionally
incorrect. Pointers to documentation problems, or an entirely
rewritten manual, would be appreciated.
There is some BFD internals documentation in doc/bfdint.texi which may
help programmers who want to modify BFD.
BFD is normally built as part of another package. See the build
instructions for that package, probably in a README file in the
appropriate directory.
BFD supports the following configure options:
--target=TARGET
The default target for which to build the library. TARGET is
a configuration target triplet, such as sparc-sun-solaris.
--enable-targets=TARGET,TARGET,TARGET...
Additional targets the library should support. To include
support for all known targets, use --enable-targets=all.
--enable-64-bit-bfd
Include support for 64 bit targets. This is automatically
turned on if you explicitly request a 64 bit target, but not
for --enable-targets=all. This requires a compiler with a 64
bit integer type, such as gcc.
--enable-shared
Build BFD as a shared library.
--with-mmap
Use mmap when accessing files. This is faster on some hosts,
but slower on others. It may not work on all hosts.
Report bugs in BFD to https://sourceware.org/bugzilla/
Patches are encouraged. When sending patches, always send the output
of diff -u or diff -c from the original file to the new file. Do not
send default diff output. Do not make the diff from the new file to
the original file. Remember that any patch must not break other
systems. Remember that BFD must support cross compilation from any
host to any target, so patches which use ``#ifdef HOST'' are not
acceptable. Please also read the ``Reporting Bugs'' section of the
gcc manual.
Bug reports without patches will be remembered, but they may never get
fixed until somebody volunteers to fix them.
Copyright (C) 2012-2023 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
H.J. Lu
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