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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | INVOCATION | OPTIONS | USAGE EXAMPLES | NOTES | AUTHOR | COPYRIGHT | COLOPHON |
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ABIDW(1) Libabigail ABIDW(1)
abidw - serialize the ABI of an ELF file
abidw reads a shared library in ELF format and emits an XML
representation of its ABI to standard output. The emitted
representation format, named ABIXML, includes all the globally
defined functions and variables, along with a complete
representation of their types. It also includes a representation
of the globally defined ELF symbols of the file.
When given the --linux-tree option, this program can also handle
a Linux kernel tree. That is, a directory tree that contains
both the vmlinux binary and Linux Kernel modules. It analyses
those Linux Kernel binaries and emits an XML representation of
the interface between the kernel and its module, to standard
output. In this case, we don't call it an ABI, but a KMI (Kernel
Module Interface). The emitted KMI includes all the globally
defined functions and variables, along with a complete
representation of their types.
To generate either ABI or KMI representation, by default abidw
uses debug information in the DWARF format, if present, otherwise
it looks for debug information in CTF or BTF formats, if present.
Finally, if no debug info in these formats is found, it only
considers ELF symbols and report about their addition or removal.
This tool uses the libabigail library to analyze the binary as
well as its associated debug information. Here is its general
mode of operation.
When instructed to do so, a binary and its associated debug
information is read and analyzed. To that effect, libabigail
analyzes by default the descriptions of the types reachable by
the interfaces (functions and variables) that are visible outside
of their translation unit. Once that analysis is done, an
Application Binary Interface Corpus is constructed by only
considering the subset of types reachable from interfaces
associated to ELF symbols that are defined and exported by the
binary. It's that final ABI corpus which libabigail considers as
representing the ABI of the analyzed binary.
Libabigail then has capabilities to generate textual
representations of ABI Corpora, compare them, analyze their
changes and report about them.
abidw [options] [<path-to-elf-file>]
• --help | -h
Display a short help about the command and exit.
• --version | -v
Display the version of the program and exit.
• --abixml-version
Display the version of the ABIXML format emitted by this
program and exit.
• --add-binaries <bin1,bin2,...>
For each of the comma-separated binaries given in argument
to this option, if the binary is found in the directory
specified by the --added-binaries-dir option, then load the
ABI corpus of the binary and add it to a set of ABI corpora
(called a ABI Corpus Group) made of the binary denoted by
the Argument of abidw. That corpus group is then serialized
out.
• --follow-dependencies
For each dependency of the input binary of abidw, if it is
found in the directory specified by the --added-binaries-dir
option, then construct an ABI corpus out of the dependency
and add it to a set of ABI corpora (called an ABI Corpus
Group) along with the ABI corpus of the input binary of the
program. The ABI Corpus Group is then serialized out.
• --list-dependencies
For each dependency of the input binary of``abidw``, if it's
found in the directory specified by the --added-binaries-dir
option, then the name of the dependency is printed out.
• --added-binaries-dir | --abd <dir-path>
This option is to be used in conjunction with the
--add-binaries, the --follow-dependencies or the
--list-dependencies option. Binaries listed as arguments of
the --add-binaries option or being dependencies of the input
binary in the case of the --follow-dependencies option and
found in the directory <dir-path> are going to be loaded as
ABI corpus and added to the set of ABI corpora (called an
ABI corpus group) built and serialized.
• --debug-info-dir | -d <dir-path>
In cases where the debug info for path-to-elf-file is in a
separate file that is located in a non-standard place, this
tells abidw where to look for that debug info file.
Note that dir-path must point to the root directory under
which the debug information is arranged in a tree-like
manner. Under Red Hat based systems, that directory is
usually <root>/usr/lib/debug.
This option can be provided several times with different
root directories. In that case, abidw will potentially look
into all those root directories to find the split debug info
for the elf file.
Note that this option is not mandatory for split debug
information installed by your system's package manager
because then abidw knows where to find it.
• --out-file | -o <file-path>
This option instructs abidw to emit the XML representation
of path-to-elf-file into the file file-path, rather than
emitting it to its standard output.
• --noout
This option instructs abidw to not emit the XML
representation of the ABI. So it only reads the ELF and
debug information, builds the internal representation of the
ABI and exits. This option is usually useful for debugging
purposes.
• --no-corpus-path
Do not emit the path attribute for the ABI corpus.
• --suppressions | suppr
<path-to-suppression-specifications-file>
Use a suppression specification file located at
path-to-suppression-specifications-file. Note that this
option can appear multiple times on the command line. In
that case, all of the provided suppression specification
files are taken into account. ABI artifacts matched by the
suppression specifications are suppressed from the output of
this tool.
• --kmi-whitelist | -kaw <path-to-whitelist>
When analyzing a Linux Kernel binary, this option points to
the white list of names of ELF symbols of functions and
variables which ABI must be written out. That white list is
called a " Kernel Module Interface white list". This is
because for the Kernel, we don't talk about the ABI; we
rather talk about the interface between the Kernel and its
module. Hence the term KMI rather than ABI
Any other function or variable which ELF symbol are not
present in that white list will not be considered by the KMI
writing process.
If this option is not provided -- thus if no white list is
provided -- then the entire KMI, that is, all publicly
defined and exported functions and global variables by the
Linux Kernel binaries is emitted.
• --linux-tree | --lt
Make abidw to consider the input path as a path to a
directory containing the vmlinux binary as several kernel
modules binaries. In that case, this program emits the
representation of the Kernel Module Interface (KMI) on the
standard output.
Below is an example of usage of abidw on a Linux Kernel
tree.
First, checkout a Linux Kernel source tree and build it.
Then install the kernel modules in a directory somewhere.
Copy the vmlinux binary into that directory too. And then
serialize the KMI of that kernel to disk, using abidw:
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
$ cd linux && git checkout v4.5
$ make allyesconfig all
$ mkdir build-output
$ make INSTALL_MOD_PATH=./build-output modules_install
$ cp vmlinux build-output/modules/4.5.0
$ abidw --linux-tree build-output/modules/4.5.0 > build-output/linux-4.5.0.kmi
• --headers-dir | --hd <headers-directory-path-1>
Specifies where to find the public headers of the binary
that the tool has to consider. The tool will thus filter
out types that are not defined in public headers.
Note that several public header directories can be specified
for the binary to consider. In that case the --header-dir
option should be present several times on the command line,
like in the following example:
$ abidw --header-dir /some/path \
--header-dir /some/other/path \
binary > binary.abi
• --header-file | --hf <header-file-path>
Specifies where to find one of the public headers of the abi
file that the tool has to consider. The tool will thus
filter out types that are not defined in public headers.
• --drop-private-types
This option is to be used with the --headers-dir and/or
header-file options. With this option, types that are NOT
defined in the headers are entirely dropped from the
internal representation build by Libabigail to represent the
ABI and will not end up in the abi XML file.
• --no-elf-needed
Do not include the list of DT_NEEDED dependency names in the
corpus.
• --drop-undefined-syms
With this option functions or variables for which the
(exported) ELF symbol is undefined are dropped from the
internal representation build by Libabigail to represent the
ABI and will not end up in the abi XML file.
• --exported-interfaces-only
By default, when looking at the debug information
accompanying a binary, this tool analyzes the descriptions
of the types reachable by the interfaces (functions and
variables) that are visible outside of their translation
unit. Once that analysis is done, an ABI corpus is
constructed by only considering the subset of types
reachable from interfaces associated to ELF symbols that are
defined and exported by the binary. It's that final ABI
corpus which textual representation is saved as ABIXML.
The problem with that approach however is that analyzing all
the interfaces that are visible from outside their
translation unit can amount to a lot of data, especially
when those binaries are applications, as opposed to shared
libraries. One example of such applications is the Linux
Kernel. Analyzing massive ABI corpora like these can be
extremely slow.
To mitigate that performance issue, this option allows
libabigail to only analyze types that are reachable from
interfaces associated with defined and exported ELF symbols.
Note that this option is turned on by default when analyzing
the Linux Kernel. Otherwise, it's turned off by default.
• --allow-non-exported-interfaces
When looking at the debug information accompanying a binary,
this tool analyzes the descriptions of the types reachable
by the interfaces (functions and variables) that are visible
outside of their translation unit. Once that analysis is
done, an ABI corpus is constructed by only considering the
subset of types reachable from interfaces associated to ELF
symbols that are defined and exported by the binary. It's
that final ABI corpus which textual representation is saved
as ABIXML.
The problem with that approach however is that analyzing all
the interfaces that are visible from outside their
translation unit can amount to a lot of data, especially
when those binaries are applications, as opposed to shared
libraries. One example of such applications is the Linux
Kernel. Analyzing massive ABI corpora like these can be
extremely slow.
In the presence of an "average sized" binary however one can
afford having libabigail analyze all interfaces that are
visible outside of their translation unit, using this
option.
Note that this option is turned on by default, unless we are
in the presence of the Linux Kernel.
• --no-linux-kernel-mode
Without this option, if abipkgiff detects that the binaries
it is looking at are Linux Kernel binaries (either vmlinux
or modules) then it only considers functions and variables
which ELF symbols are listed in the __ksymtab and
__ksymtab_gpl sections.
With this option, abipkgdiff considers the binary as a
non-special ELF binary. It thus considers functions and
variables which are defined and exported in the ELF sense.
• --check-alternate-debug-info <elf-path>
If the debug info for the file elf-path contains a reference
to an alternate debug info file, abidw checks that it can
find that alternate debug info file. In that case, it emits
a meaningful success message mentioning the full path to the
alternate debug info file found. Otherwise, it emits an
error code.
• --no-show-locs
In the emitted ABI representation, do not show file, line
or column where ABI artifacts are defined.
• --no-parameter-names
In the emitted ABI representation, do not show names of
function parameters, just the types.
• --no-write-default-sizes
In the XML ABI representation, do not write the size-in-bits
for pointer type definitions, reference type definitions,
function declarations and function types when they are equal
to the default address size of the translation unit. Note
that libabigail before 1.8 will not set the default size and
will interpret types without a size-in-bits attribute as
zero sized.
• --type-id-style <sequence``|``hash>
This option controls how types are idenfied in the generated
XML files. The default sequence style just numbers (with
type-id- as prefix) the types in the order they are
encountered. The hash style uses a (stable, portable) hash
of libabigail's internal type names and is intended to make
the XML files easier to diff.
• --check-alternate-debug-info-base-name <elf-path>
Like --check-alternate-debug-info, but in the success
message, only mention the base name of the debug info file;
not its full path.
• --load-all-types
By default, libabigail (and thus abidw) only loads types
that are reachable from functions and variables declarations
that are publicly defined and exported by the binary. So
only those types are present in the output of abidw. This
option however makes abidw load all the types defined in the
binaries, even those that are not reachable from public
declarations.
• --no-load-undefined-interfaces
By default, libabigail (and thus abidw) loads information
about undefined function and variable symbols as well as
functions and variables that are associated with those
undefined symbols. Those are called undefined interfaces.
This option however makes makes abidw avoid loading
information about undefined interfaces. The resulting XML
file thus doesn't contain information about those undefined
interfaces.
• --abidiff
Load the ABI of the ELF binary given in argument, save it
in libabigail's XML format in a temporary file; read the
ABI from the temporary XML file and compare the ABI that
has been read back against the ABI of the ELF binary given
in argument. The ABIs should compare equal. If they
don't, the program emits a diagnostic and exits with a
non-zero code.
This is a debugging and sanity check option.
• --debug-abidiff
Same as --abidiff but in debug mode. In this mode, error
messages are emitted for types which fail type
canonicalization.
This is an optional debugging and sanity check option. To
enable it the libabigail package needs to be configured
with the --enable-debug-self-comparison option.
• --debug-type-canonicalization | --debug-tc
Debug the type canonicalization process. This is done by
using structural and canonical equality when
canonicalizing every single type. Structural and
canonical equality should yield the same result. If they
don't yield the same result for a given type, then it
means that the canonicalization of that type went wrong.
In that case, an error message is emitted and the
execution of the program is aborted.
This option is available only if the package was
configured with the --enable-debug-type-canonicalization
option.
• --no-assume-odr-for-cplusplus
When analysing a binary originating from C++ code using
DWARF debug information, libabigail assumes the One
Definition Rule to speed-up the analysis. In that case,
when several types have the same name in the binary, they
are assumed to all be equal.
This option disables that assumption and instructs
libabigail to actually actually compare the types to
determine if they are equal.
• --no-leverage-dwarf-factorization
When analysing a binary which DWARF debug information was
processed with the DWZ tool, the type information is
supposed to be already factorized. That context is used by
libabigail to perform some speed optimizations.
This option disables those optimizations.
• --ctf
Extract ABI information from CTF debug information, if
present in the given object.
• --annotate
Annotate the ABIXML output with comments above most
elements. The comments are made of the pretty-printed
form types, declaration or even ELF symbols. The purpose
is to make the ABIXML output more human-readable for
debugging or documenting purposes.
• --stats
Emit statistics about various internal things.
• --verbose
Emit verbose logs about the progress of miscellaneous
internal things.
1. Emitting an ABIXML representation of a binary:
$ abidw binary > binary.abi
2. Emitting an ABIXML representation of a set of binaries
specified on the command line:
$ abidw --added-binaries=bin1,bin2,bin3 \
--added-binaries-dir /some/where \
binary > binaries.abi
Note that the binaries bin1, bin2 and bin3 are to be found
in the directory /some/where. A representation of the ABI
of the set of binaries binary, bin1, bin2 and bin3 called
an ABI corpus group is serialized in the file binaries.abi.
3. Emitting an ABIXML representation of a binary and its
dependencies:
$ abidw --follow-dependencies \
--added-binaries-dir /some/where \
binary > binary.abi
Note that only the dependencies that are found in the
directory /some/where are analysed. Their ABIs, along with
the ABI the binary named binary are represented as an ABI
corpus group and serialized in the file binary.abi, in the
ABIXML format.
Alternate debug info files
As of the version 4 of the DWARF specification, Alternate debug
information is a GNU extension to the DWARF specification. It
has however been proposed for inclusion into the upcoming version
5 of the DWARF standard. You can read more about the GNU
extensions to the DWARF standard here.
Dodji Seketeli
2014-2022, Red Hat, Inc.
This page is part of the libabigail (ABI Generic Analysis and
Instrumentation Library) project. Information about the project
can be found at ⟨https://sourceware.org/libabigail/⟩. If you
have a bug report for this manual page, see
⟨http://sourceware.org/bugzilla/enter_bug.cgi?product=libabigail⟩.
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/libabigail.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-05-31.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
Jun 14, 2024 ABIDW(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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