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4b8377e7db
Correct a MIPS/BFD linker issue with dynamic symbol and corresponding
GOT entry values being redirected to lazy binding stubs where the stubs
section has been discarded by assigning to the `/DISCARD/' output
section in the linker script used. The issue manifests itself by the
values entered being relative to the absolute section, which is what any
discarded sections are internally assigned in the linker.
For the `stub-dynsym-2.s' piece of code included as a test case with
this change this issue results in the dynamic symbol table and the GOT
looking like:
Symbol table '.dynsym' contains 3 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000010 0 FUNC GLOBAL DEFAULT UND bar
2: 00000000 0 FUNC GLOBAL DEFAULT UND foo
Primary GOT:
Canonical gp value: 00097ff0
Reserved entries:
Address Access Initial Purpose
00090000 -32752(gp) 00000000 Lazy resolver
00090004 -32748(gp) 80000000 Module pointer (GNU extension)
Global entries:
Address Access Initial Sym.Val. Type Ndx Name
00090008 -32744(gp) 00000010 00000010 FUNC UND bar
0009000c -32740(gp) 00000000 00000000 FUNC UND foo
if assembled to regular MIPS code, or:
Symbol table '.dynsym' contains 3 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000d 0 FUNC GLOBAL DEFAULT UND bar
2: 00000001 0 FUNC GLOBAL DEFAULT UND foo
Primary GOT:
Canonical gp value: 00097ff0
Reserved entries:
Address Access Initial Purpose
00090000 -32752(gp) 00000000 Lazy resolver
00090004 -32748(gp) 80000000 Module pointer (GNU extension)
Global entries:
Address Access Initial Sym.Val. Type Ndx Name
00090008 -32744(gp) 0000000d 0000000d FUNC UND bar
0009000c -32740(gp) 00000001 00000001 FUNC UND foo
if assembled to microMIPS code. Symbol values and GOT entries record
the offset into the inexistent stubs section and the ISA bit rather than
zero, which would be the case if a lazy binding stub was not used for
other reasons, such as the value of the symbol being taken for a purpose
other than making a function call (e.g. an R_MIPS_GOT16 relocation).
Correct the issue by refraining from redirecting symbols to lazy binding
stubs if the stubs section is going to be discarded.
bfd/
* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol): Don't set
`->needs_lazy_stub' if the stubs output section is the absolute
section.
ld/
* testsuite/ld-mips-elf/stub-dynsym-2.dd: New test.
* testsuite/ld-mips-elf/stub-dynsym-2.gd: New test.
* testsuite/ld-mips-elf/stub-dynsym-2.sd: New test.
* testsuite/ld-mips-elf/stub-dynsym-discard-2.gd: New test.
* testsuite/ld-mips-elf/stub-dynsym-discard-2.sd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-2.dd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-2.gd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-2.sd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.dd: New
test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.gd: New
test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.sd: New
test.
* testsuite/ld-mips-elf/stub-dynsym-2.ld: New test linker
script.
* testsuite/ld-mips-elf/stub-dynsym-discard-2.ld: New test
linker script.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
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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-2017 | ||
| 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.texi | ||
| 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.texi | ||
| 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.texi), as well as the
beginnings of an internals manual (ldint.texi).
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.texi 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) 2012-2018 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.