cbd0eecf26
Currently, linker will define __start_SECNAME and __stop_SECNAME symbols only for orphaned sections. However, during garbage collection, ELF linker marks all sections with references to __start_SECNAME and __stop_SECNAME symbols as used even when section SECNAME isn't an orphaned section and linker won't define __start_SECNAME nor __stop_SECNAME. And ELF linker stores the first input section whose name matches __start_SECNAME or __stop_SECNAME in u.undef.section for garbage collection. If these symbols are provided in linker script, u.undef.section is set to the section where they will defined by linker script, which leads to the incorrect output. This patch changes linker to always define referenced __start_SECNAME and __stop_SECNAME if the input section name is the same as the output section name, which is always true for orphaned sections, and SECNAME is a C identifier. Also __start_SECNAME and __stop_SECNAME symbols are marked as hidden by ELF linker so that __start_SECNAME and __stop_SECNAME symbols for section SECNAME in different modules are unique. For garbage collection, ELF linker stores the first matched input section in the unused vtable field. bfd/ PR ld/20022 PR ld/21557 PR ld/21562 PR ld/21571 * elf-bfd.h (elf_link_hash_entry): Add start_stop. Change the vtable field to a union. (_bfd_elf_is_start_stop): Removed. * elf32-i386.c (elf_i386_convert_load_reloc): Also check for __start_SECNAME and __stop_SECNAME symbols. * elf64-x86-64.c (elf_x86_64_convert_load_reloc): Likewise. * elflink.c (_bfd_elf_is_start_stop): Removed. (_bfd_elf_gc_mark_rsec): Check start_stop instead of calling _bfd_elf_is_start_stop. (elf_gc_propagate_vtable_entries_used): Skip __start_SECNAME and __stop_SECNAME symbols. Updated. (elf_gc_smash_unused_vtentry_relocs): Likewise. (bfd_elf_gc_record_vtinherit): Likewise. (bfd_elf_gc_record_vtentry): Likewise. ld/ PR ld/20022 PR ld/21557 PR ld/21562 PR ld/21571 * ld.texinfo: Update __start_SECNAME/__stop_SECNAME symbols. * ldlang.c (lang_insert_orphan): Move handling of __start_SECNAME and __stop_SECNAME symbols to ... (lang_set_startof): Here. Also define __start_SECNAME and __stop_SECNAME for -Ur. * emultempl/elf32.em (gld${EMULATION_NAME}_after_open): Mark referenced __start_SECNAME and __stop_SECNAME symbols as hidden and set start_stop for garbage collection. * testsuite/ld-elf/pr21562a.d: New file. * testsuite/ld-elf/pr21562a.s: Likewise. * testsuite/ld-elf/pr21562a.t: Likewise. * testsuite/ld-elf/pr21562b.d: Likewise. * testsuite/ld-elf/pr21562b.s: Likewise. * testsuite/ld-elf/pr21562b.t: Likewise. * testsuite/ld-elf/pr21562c.d: Likewise. * testsuite/ld-elf/pr21562c.t: Likewise. * testsuite/ld-elf/pr21562d.d: Likewise. * testsuite/ld-elf/pr21562d.t: Likewise. * testsuite/ld-elf/pr21562e.d: Likewise. * testsuite/ld-elf/pr21562f.d: Likewise. * testsuite/ld-elf/pr21562g.d: Likewise. * testsuite/ld-elf/pr21562h.d: Likewise. * testsuite/ld-elf/pr21562i.d: Likewise. * testsuite/ld-elf/pr21562j.d: Likewise. * testsuite/ld-elf/pr21562k.d: Likewise. * testsuite/ld-elf/pr21562l.d: Likewise. * testsuite/ld-elf/pr21562m.d: Likewise. * testsuite/ld-elf/pr21562n.d: Likewise. * testsuite/ld-gc/pr20022.d: Likewise. * testsuite/ld-gc/pr20022a.s: Likewise. * testsuite/ld-gc/pr20022b.s: Likewise. * testsuite/ld-gc/gc.exp: Run PR ld/20022 tests. * testsuite/ld-gc/pr19161.d: Also accept local __start_SECNAME symbol. * testsuite/ld-gc/start.d: Likewise. * testsuite/ld-x86-64/lea1a.d: Updated. * testsuite/ld-x86-64/lea1b.d: Updated. * testsuite/ld-x86-64/lea1d.d: Updated. * testsuite/ld-x86-64/lea1e.d: Likewise. |
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.. | ||
emulparams | ||
emultempl | ||
po | ||
scripttempl | ||
testsuite | ||
.gitignore | ||
aclocal.m4 | ||
ChangeLog | ||
ChangeLog-0001 | ||
ChangeLog-0203 | ||
ChangeLog-2004 | ||
ChangeLog-2005 | ||
ChangeLog-2006 | ||
ChangeLog-2007 | ||
ChangeLog-2008 | ||
ChangeLog-2009 | ||
ChangeLog-2010 | ||
ChangeLog-2011 | ||
ChangeLog-2012 | ||
ChangeLog-2013 | ||
ChangeLog-2014 | ||
ChangeLog-2015 | ||
ChangeLog-2016 | ||
ChangeLog-9197 | ||
ChangeLog-9899 | ||
config.in | ||
configure | ||
configure.ac | ||
configure.host | ||
configure.tgt | ||
deffile.h | ||
deffilep.y | ||
dep-in.sed | ||
elf-hints-local.h | ||
fdl.texi | ||
gen-doc.texi | ||
genscrba.sh | ||
genscripts.sh | ||
h8-doc.texi | ||
ld.h | ||
ld.texinfo | ||
ldbuildid.c | ||
ldbuildid.h | ||
ldcref.c | ||
ldctor.c | ||
ldctor.h | ||
ldemul.c | ||
ldemul.h | ||
ldexp.c | ||
ldexp.h | ||
ldfile.c | ||
ldfile.h | ||
ldgram.y | ||
ldint.texinfo | ||
ldlang.c | ||
ldlang.h | ||
ldlex-wrapper.c | ||
ldlex.h | ||
ldlex.l | ||
ldmain.c | ||
ldmain.h | ||
ldmisc.c | ||
ldmisc.h | ||
ldver.c | ||
ldver.h | ||
ldwrite.c | ||
ldwrite.h | ||
lexsup.c | ||
MAINTAINERS | ||
Makefile.am | ||
Makefile.in | ||
mri.c | ||
mri.h | ||
NEWS | ||
pe-dll.c | ||
pe-dll.h | ||
pep-dll.c | ||
pep-dll.h | ||
plugin.c | ||
plugin.h | ||
README | ||
stamp-h.in | ||
sysdep.h | ||
testplug2.c | ||
testplug3.c | ||
testplug4.c | ||
testplug.c | ||
TODO |
README for LD
This is the GNU linker. It is distributed with other "binary
utilities" which should be in ../binutils. See ../binutils/README for
more general notes, including where to send bug reports.
There are many features of the linker:
* The linker uses a Binary File Descriptor library (../bfd)
that it uses to read and write object files. This helps
insulate the linker itself from the format of object files.
* The linker supports a number of different object file
formats. It can even handle multiple formats at once:
Read two input formats and write a third.
* The linker can be configured for cross-linking.
* The linker supports a control language.
* There is a user manual (ld.texinfo), as well as the
beginnings of an internals manual (ldint.texinfo).
Installation
============
See ../binutils/README.
If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.
To build just the linker, make the target all-ld from the top level
directory (one directory above this one).
Porting to a new target
=======================
See the ldint.texinfo manual.
Reporting bugs etc
===========================
See ../binutils/README.
Known problems
==============
The Solaris linker normally exports all dynamic symbols from an
executable. The GNU linker does not do this by default. This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets). This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl. You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.
HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly. The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages. There are various
workarounds to this:
* Build and install bash, and build with "make SHELL=bash".
* Update to a version of HP/UX with a working shell (e.g., 9.05).
* Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
emulparams script used exports any shell variables it sets.
Copyright (C) 2012-2017 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.