Go to file
Tamar Christina 796d6298bb Arm: Fix Arm disassembler mapping symbol search.
Similar to the AArch64 patches the Arm disassembler has the same issues with
out of order sections but also a few short comings.

For one thing there are multiple code blocks to determine mapping symbols, and
they all work slightly different, and neither fully correct.  The first thing
this patch does is centralise the mapping symbols search into one function
mapping_symbol_for_insn.  This function is then updated to perform a search in
a similar way as AArch64.

Their used to be a value has_mapping_symbols which was used to determine the
default disassembly for objects that have no mapping symbols.  The problem with
the approach was that it was determining this value in the same loop that needed
it, which is why this field could take on the states -1, 0, 1 where -1 means
"don't know".  However this means that until you actually find a mapping symbol
or reach the end of the disassembly glob, you don't know if you did the right
action or not, and if you didn't you can't correct it anymore.

This is why the two jump-reloc-veneers-* testcases end up disassembling some
insn as data when they shouldn't.

Out of order here refers to an object file where sections are not listed in a
monotonic increasing VMA order.

The ELF ABI for Arm [1] specifies the following for mapping symbols:

  1) A text section must always have a corresponding mapping symbol at it's
     start.
  2) Data sections do not require any mapping symbols.
  3) The range of a mapping symbol extends from the address it starts on up to
     the next mapping symbol (exclusive) or section end (inclusive).

However there is no defined order between a symbol and it's corresponding
mapping symbol in the symbol table.  This means that while in general we look
up for a corresponding mapping symbol, we have to make at least one check of
the symbol below the address being disassembled.

When disassembling different PCs within the same section, the search for mapping
symbol can be cached somewhat.  We know that the mapping symbol corresponding to
the current PC is either the previous one used, or one at the same address as
the current PC.

However this optimization and mapping symbol search must stop as soon as we
reach the end or start of the section.  Furthermore if we're only disassembling
a part of a section, the search is a allowed to search further than the current
chunk, but is not allowed to search past it (The mapping symbol if there, must
be at the same address, so in practice we usually stop at PC+4).

lastly, since only data sections don't require a mapping symbol the default
mapping type should be DATA and not INSN as previously defined, however if the
binary has had all its symbols stripped than this isn't very useful.  To fix
this we determine the default based on the section flags.  This will allow the
disassembler to be more useful on stripped binaries.  If there is no section
than we assume you to be disassembling INSN.

[1] https://developer.arm.com/docs/ihi0044/latest/elf-for-the-arm-architecture-abi-2018q4-documentation#aaelf32-table4-7

binutils/ChangeLog:

	* testsuite/binutils-all/arm/in-order-all.d: New test.
	* testsuite/binutils-all/arm/in-order.d: New test.
	* testsuite/binutils-all/arm/objdump.exp: Support .d tests.
	* testsuite/binutils-all/arm/out-of-order-all.d: New test.
	* testsuite/binutils-all/arm/out-of-order.T: New test.
	* testsuite/binutils-all/arm/out-of-order.d: New test.
	* testsuite/binutils-all/arm/out-of-order.s: New test.

ld/ChangeLog:

	* testsuite/ld-arm/jump-reloc-veneers-cond-long.d: Update disassembly.
	* testsuite/ld-arm/jump-reloc-veneers-long.d: Update disassembly.

opcodes/ChangeLog:

	* arm-dis.c (struct arm_private_data): Remove has_mapping_symbols.
	(mapping_symbol_for_insn): Implement new algorithm.
	(print_insn): Remove duplicate code.
2019-03-25 15:05:53 +00:00
bfd Automatic date update in version.in 2019-03-25 00:00:31 +00:00
binutils Arm: Fix Arm disassembler mapping symbol search. 2019-03-25 15:05:53 +00:00
config
contrib
cpu
elfcpp
etc
gas Remove strip_underscore from struct emulation 2019-03-21 08:50:24 +10:30
gdb Fix testsuite hangs when gdb_test_multiple body errors out 2019-03-25 13:26:23 +00:00
gold
gprof
include AArch64: Fix disassembler bug with out-of-order sections 2019-03-25 15:05:53 +00:00
intl
ld Arm: Fix Arm disassembler mapping symbol search. 2019-03-25 15:05:53 +00:00
libdecnumber
libiberty
opcodes Arm: Fix Arm disassembler mapping symbol search. 2019-03-25 15:05:53 +00:00
readline
sim
texinfo
zlib
.cvsignore
.gitattributes
.gitignore
ar-lib
ChangeLog
compile
config-ml.in
config.guess
config.rpath
config.sub
configure
configure.ac
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
depcomp
djunpack.bat
install-sh
libtool.m4
lt~obsolete.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS
Makefile.def
Makefile.in
Makefile.tpl
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
multilib.am
README
README-maintainer-mode
setup.com
src-release.sh
symlink-tree
test-driver
ylwrap

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.