objdump
display information from object files.
see also :
nm - readelf
Synopsis
objdump
[-a|--archive-headers]
[-b
bfdname|--target=bfdname]
[-C|--demangle[=style]
]
[-d|--disassemble]
[-D|--disassemble-all]
[-z|--disassemble-zeroes]
[-EB|-EL|--endian={big
| little }]
[-f|--file-headers]
[-F|--file-offsets]
[--file-start-context]
[-g|--debugging]
[-e|--debugging-tags]
[-h|--section-headers|--headers]
[-i|--info]
[-j
section|--section=section]
[-l|--line-numbers]
[-S|--source]
[-m
machine|--architecture=machine]
[-M
options|--disassembler-options=options]
[-p|--private-headers]
[-P
options|--private=options]
[-r|--reloc]
[-R|--dynamic-reloc]
[-s|--full-contents]
[-W[lLiaprmfFsoRt]|
--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index]]
[-G|--stabs]
[-t|--syms]
[-T|--dynamic-syms]
[-x|--all-headers]
[-w|--wide]
[--start-address=address]
[--stop-address=address]
[--prefix-addresses]
[--[no-]show-raw-insn]
[--adjust-vma=offset]
[--special-syms]
[--prefix=prefix]
[--prefix-strip=level]
[--insn-width=width]
[-V|--version]
[-H|--help]
objfile...
add an example, a script, a trick and tips
examples
source
all:
objdump -S -j .text main.elf > m.lst
objdump -S -j .rodata main.elf >> m.lst
objdump -S -j .data main.elf >> m.lst
objdump -S -j .data main.elf >> m.lst
else:
nm add.o
nm max.o
nm hello.o
objdump -f hello
objdump -d hello.o
objdump -d add.o
objdump -d max.o
objdump -d hello
description
objdump
displays information about one or more object files. The
options control what particular information to display. This
information is mostly useful to programmers who are working
on the compilation tools, as opposed to programmers who just
want their program to compile and work.
objfile...
are the object files to be examined. When you specify
archives, objdump shows information on each of the
member object files.
options
The long and
short forms of options, shown here as alternatives, are
equivalent. At least one option from the list
-a,-d,-D,-e,-f,-g,-G,-h,-H,-p,-P,-r,-R,-s,-S,-t,-T,-V,-x
must be given.
--archive-header
If any of the objfile
files are archives, display the archive header information
(in a format similar to ls -l). Besides the
information you could list with ar tv, objdump
-a shows the object file format of each archive
member.
--adjust-vma=offset
When dumping information, first
add offset to all the section addresses. This is
useful if the section addresses do not correspond to the
symbol table, which can happen when putting sections at
particular addresses when using a format which can not
represent section addresses, such as a.out.
-b bfdname
--target=bfdname
Specify that the object-code
format for the object files is bfdname. This option
may not be necessary; objdump can automatically
recognize many formats.
For
example,
objdump -b oasys -m vax -h fu.o
displays
summary information from the section headers
(-h) of fu.o, which is explicitly
identified (-m) as a VAX object
file in the format produced by Oasys compilers. You can list
the formats available with the -i option.
--demangle[=style]
Decode (demangle)
low-level symbol names into user-level names. Besides
removing any initial underscore prepended by the system,
this makes C ++ function names readable.
Different compilers have different mangling styles. The
optional demangling style argument can be used to choose an
appropriate demangling style for your compiler.
--debugging
Display debugging information.
This attempts to parse STABS and
IEEE debugging format information stored in
the file and print it out using a C like syntax. If neither
of these formats are found this option falls back on the
-W option to print any DWARF
information in the file.
--debugging-tags
Like -g, but the
information is generated in a format compatible with ctags
tool.
--disassemble
Display the assembler mnemonics
for the machine instructions from objfile. This
option only disassembles those sections which are expected
to contain instructions.
--disassemble-all
Like -d, but
disassemble the contents of all sections, not just those
expected to contain instructions.
If the target
is an ARM architecture this switch also has
the effect of forcing the disassembler to decode pieces of
data found in code sections as if they were
instructions.
--prefix-addresses
When disassembling, print the
complete address on each line. This is the older disassembly
format.
--endian={big|little}
Specify the endianness of the
object files. This only affects disassembly. This can be
useful when disassembling a file format which does not
describe endianness information, such as
S-records.
--file-headers
Display summary information
from the overall header of each of the objfile
files.
--file-offsets
When disassembling sections,
whenever a symbol is displayed, also display the file offset
of the region of data that is about to be dumped. If zeroes
are being skipped, then when disassembly resumes, tell the
user how many zeroes were skipped and the file offset of the
location from where the disassembly resumes. When dumping
sections, display the file offset of the location from where
the dump starts.
--file-start-context
Specify that when displaying
interlisted source code/disassembly (assumes
-S) from a file that has not yet been
displayed, extend the context to the start of the file.
--section-headers
--headers
Display summary information
from the section headers of the object file.
File segments
may be relocated to nonstandard addresses, for example by
using the -Ttext, -Tdata, or
-Tbss options to ld. However, some
object file formats, such as a.out, do not store the
starting address of the file segments. In those situations,
although ld relocates the sections correctly, using
objdump -h to list the file section headers
cannot show the correct addresses. Instead, it shows the
usual addresses, which are implicit for the target.
--help
Print a summary of the options
to objdump and exit.
--info
Display a list showing all
architectures and object formats available for specification
with -b or -m.
-j name
--section=name
Display information only for
section name.
--line-numbers
Label the display (using
debugging information) with the filename and source line
numbers corresponding to the object code or relocs shown.
Only useful with -d, -D, or
-r.
-m machine
--architecture=machine
Specify the architecture to use
when disassembling object files. This can be useful when
disassembling object files which do not describe
architecture information, such as S-records. You can
list the available architectures with the -i
option.
If the target
is an ARM architecture then this switch has
an additional effect. It restricts the disassembly to only
those instructions supported by the architecture specified
by machine. If it is necessary to use this switch
because the input file does not contain any architecture
information, but it is also desired to disassemble all the
instructions use -marm.
-M options
--disassembler-options=options
Pass target specific
information to the disassembler. Only supported on some
targets. If it is necessary to specify more than one
disassembler option then multiple -M options
can be used or can be placed together into a comma separated
list.
If the target
is an ARM architecture then this switch can
be used to select which register name set is used during
disassembler. Specifying -M reg-names-std (the
default) will select the register names as used in
ARM ’s instruction set documentation,
but with register 13 called ’sp’, register 14
called ’lr’ and register 15 called
’pc’. Specifying -M reg-names-apcs
will select the name set used by the ARM
Procedure Call Standard, whilst specifying -M
reg-names-raw will just use r followed by the
register number.
There are also
two variants on the APCS register naming
scheme enabled by -M reg-names-atpcs and
-M reg-names-special-atpcs which use the
ARM/Thumb Procedure Call Standard naming conventions.
(Either with the normal register names or the special
register names).
This option can
also be used for ARM architectures to force
the disassembler to interpret all instructions as Thumb
instructions by using the switch
--disassembler-options=force-thumb.
This can be useful when attempting to disassemble thumb code
produced by other compilers.
For the x86,
some of the options duplicate functions of the
-m switch, but allow finer grained control.
Multiple selections from the following may be specified as a
comma separated string. x86-64, i386 and
i8086 select disassembly for the given architecture.
intel and att select between intel syntax mode
and AT&T syntax mode.
intel-mnemonic and att-mnemonic select between
intel mnemonic mode and AT&T mnemonic
mode. intel-mnemonic implies intel and
att-mnemonic implies att. addr64,
addr32, addr16, data32 and
data16 specify the default address size and operand
size. These four options will be overridden if
x86-64, i386 or i8086 appear
later in the option string. Lastly, suffix, when in
AT&T mode, instructs the disassembler to
print a mnemonic suffix even when the suffix could be
inferred by the operands.
For PowerPC,
booke controls the disassembly of BookE instructions.
32 and 64 select PowerPC and PowerPC64
disassembly, respectively. e300 selects disassembly
for the e300 family. 440 selects disassembly for the
PowerPC 440. ppcps selects disassembly for the paired
single instructions of the PPC750CL .
For
MIPS , this option controls the printing of
instruction mnemonic names and register names in
disassembled instructions. Multiple selections from the
following may be specified as a comma separated string, and
invalid options are ignored:
"no-aliases"
Print the ’raw’
instruction mnemonic instead of some pseudo instruction
mnemonic. I.e., print ’daddu’ or
’or’ instead of ’move’,
’sll’ instead of ’nop’, etc.
"gpr-names=ABI"
Print GPR
(general-purpose register) names as appropriate for the
specified ABI . By default,
GPR names are selected according to the
ABI of the binary being disassembled.
"fpr-names=ABI"
Print FPR
(floating-point register) names as appropriate for the
specified ABI . By default,
FPR numbers are printed rather than
names.
"cp0-names=ARCH"
Print CP0
(system control coprocessor; coprocessor 0) register names
as appropriate for the CPU or architecture
specified by ARCH . By default,
CP0 register names are selected according to
the architecture and CPU of the binary being
disassembled.
"hwr-names=ARCH"
Print HWR
(hardware register, used by the "rdhwr"
instruction) names as appropriate for the CPU
or architecture specified by ARCH . By
default, HWR names are selected according to
the architecture and CPU of the binary being
disassembled.
"reg-names=ABI"
Print GPR and
FPR names as appropriate for the selected
ABI .
"reg-names=ARCH"
Print CPU-specific register
names ( CP0 register and HWR
names) as appropriate for the selected CPU or
architecture.
For any of the
options listed above, ABI or
ARCH may be specified as
numeric to have numbers printed rather than names,
for the selected types of registers. You can list the
available values of ABI and
ARCH using the
--help option.
For
VAX , you can specify function entry
addresses with -M entry:0xf00ba. You can use
this multiple times to properly disassemble
VAX binary files that don’t contain
symbol tables (like ROM dumps). In these
cases, the function entry mask would otherwise be decoded as
VAX instructions, which would probably lead
the rest of the function being wrongly disassembled.
--private-headers
Print information that is
specific to the object file format. The exact information
printed depends upon the object file format. For some object
file formats, no additional information is printed.
-P options
--private=options
Print information that is
specific to the object file format. The argument
options is a comma separated list that depends on the
format (the lists of options is displayed with the
help).
For
XCOFF , the available options are:
header, aout, sections, syms,
relocs, lineno, loader, except,
typchk, traceback and toc.
--reloc
Print the relocation entries of
the file. If used with -d or -D,
the relocations are printed interspersed with the
disassembly.
--dynamic-reloc
Print the dynamic relocation
entries of the file. This is only meaningful for dynamic
objects, such as certain types of shared libraries. As for
-r, if used with -d or
-D, the relocations are printed interspersed
with the disassembly.
--full-contents
Display the full contents of
any sections requested. By default all non-empty sections
are displayed.
--source
Display source code intermixed
with disassembly, if possible. Implies -d.
--prefix=prefix
Specify prefix to add to
the absolute paths when used with -S.
--prefix-strip=level
Indicate how many initial
directory names to strip off the hardwired absolute paths.
It has no effect without
--prefix=prefix.
--show-raw-insn
When disassembling
instructions, print the instruction in hex as well as in
symbolic form. This is the default except when
--prefix-addresses is used.
--no-show-raw-insn
When disassembling
instructions, do not print the instruction bytes. This is
the default when --prefix-addresses
is used.
--insn-width=width
Display width bytes on a
single line when disassembling instructions.
-W[lLiaprmfFsoRt]
--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index]
Displays the contents of the
debug sections in the file, if any are present. If one of
the optional letters or words follows the switch then only
data found in those specific sections will be dumped.
Note that there
is no single letter option to display the content of trace
sections or .gdb_index.
Note: the
output from the =info option can also be affected by
the options --dwarf-depth, the
--dwarf-start and the
--dwarf-check.
--dwarf-depth=n
Limit the dump of the
".debug_info" section to n
children. This is only useful with
--dwarf=info. The default is to print all
DIEs; the special value 0 for n will also have this
effect.
With a non-zero
value for n, DIEs at or deeper than n levels
will not be printed. The range for n is
zero-based.
--dwarf-start=n
Print only DIEs beginning with
the DIE numbered n. This is only
useful with --dwarf=info.
If specified,
this option will suppress printing of any header information
and all DIEs before the DIE numbered
n. Only siblings and children of the specified
DIE will be printed.
This can be
used in conjunction with
--dwarf-depth.
--dwarf-check
Enable additional checks for
consistency of Dwarf information.
--stabs
Display the full contents of
any sections requested. Display the contents of the .stab
and .stab.index and .stab.excl sections from an
ELF file. This is only useful on systems
(such as Solaris 2.0) in which ".stab"
debugging symbol-table entries are carried in an
ELF section. In most other file formats,
debugging symbol-table entries are interleaved with linkage
symbols, and are visible in the --syms
output.
--start-address=address
Start displaying data at the
specified address. This affects the output of the
-d, -r and -s
options.
--stop-address=address
Stop displaying data at the
specified address. This affects the output of the
-d, -r and -s
options.
--syms
Print the symbol table entries
of the file. This is similar to the information provided by
the nm program, although the display format is
different. The format of the output depends upon the format
of the file being dumped, but there are two main types. One
looks like this:
[ 4](sec 3)(fl 0x00)(ty 0)(scl 3) (nx 1) 0x00000000 .bss
[ 6](sec 1)(fl 0x00)(ty 0)(scl 2) (nx 0) 0x00000000 fred
where the
number inside the square brackets is the number of the entry
in the symbol table, the sec number is the section
number, the fl value are the symbol’s flag
bits, the ty number is the symbol’s type, the
scl number is the symbol’s storage class and
the nx value is the number of auxilary entries
associated with the symbol. The last two fields are the
symbol’s value and its name.
The other
common output format, usually seen with ELF
based files, looks like this:
00000000 l d .bss 00000000 .bss
00000000 g .text 00000000 fred
Here the first
number is the symbol’s value (sometimes refered to as
its address). The next field is actually a set of characters
and spaces indicating the flag bits that are set on the
symbol. These characters are described below. Next is the
section with which the symbol is associated or *ABS*
if the section is absolute (ie not connected with any
section), or *UND* if the section is referenced in
the file being dumped, but not defined there.
After the
section name comes another field, a number, which for common
symbols is the alignment and for other symbol is the size.
Finally the symbol’s name is displayed.
The flag
characters are divided into 7 groups as follows:
"l"
"g"
"u"
"!"
The symbol is a local (l), global (g), unique global
(u), neither global nor local (a space) or both global and
local (!). A symbol can be neither local or global for a
variety of reasons, e.g., because it is used for debugging,
but it is probably an indication of a bug if it is ever both
local and global. Unique global symbols are a
GNU extension to the standard set of
ELF symbol bindings. For such a symbol the
dynamic linker will make sure that in the entire process
there is just one symbol with this name and type in use.
"w"
The symbol is weak (w) or strong (a space).
"C"
The symbol denotes a constructor (C) or an ordinary
symbol (a space).
"W"
The symbol is a warning (W) or a normal symbol (a
space). A warning symbol’s name is a message to be
displayed if the symbol following the warning symbol is ever
referenced.
"I"
"i"
The symbol is an indirect reference to another symbol
(I), a function to be evaluated during reloc processing (i)
or a normal symbol (a space).
"d"
"D"
The symbol is a debugging symbol (d) or a dynamic symbol
(D) or a normal symbol (a space).
"F"
"f"
"O"
The symbol is the name of a function (F) or a file (f)
or an object (O) or just a normal symbol (a space).
-T
--dynamic-syms
Print the dynamic symbol table
entries of the file. This is only meaningful for dynamic
objects, such as certain types of shared libraries. This is
similar to the information provided by the nm program
when given the -D
(--dynamic) option.
--special-syms
When displaying symbols include
those which the target considers to be special in some way
and which would not normally be of interest to the user.
--version
Print the version number of
objdump and exit.
--all-headers
Display all available header
information, including the symbol table and relocation
entries. Using -x is equivalent to specifying
all of -a -f -h -p -r
-t.
--wide
Format some lines for output
devices that have more than 80 columns. Also do not truncate
symbol names when they are displayed.
--disassemble-zeroes
Normally the disassembly output
will skip blocks of zeroes. This option directs the
disassembler to disassemble those blocks, just like any
other data.
@file
Read command-line options from
file. The options read are inserted in place of the
original @file option. If file does not exist,
or cannot be read, then the option will be treated
literally, and not removed.
Options in
file are separated by whitespace. A whitespace
character may be included in an option by surrounding the
entire option in either single or double quotes. Any
character (including a backslash) may be included by
prefixing the character to be included with a backslash. The
file may itself contain additional @file
options; any such options will be processed recursively.
copyright
Copyright (c) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
2010, 2011, 2012, 2013 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free
Documentation License, Version 1.3 or any later version published
by the Free Software Foundation; with no Invariant Sections, with
no Front-Cover Texts, and with no Back-Cover Texts. A copy of the
license is included in the section entitled " GNU
Free Documentation License".
see also
nm ,
readelf , and the Info entries for
binutils.