Before this patch, perror() function is used in some cases when bpftool
fails to parse its input file in batch mode. This function does not
integrate well with the rest of the output when JSON is used, so we
replace it by something that is compliant.
Most calls to perror() had already been replaced in a previous patch,
this one is a leftover.
Fixes: d319c8e101c5 ("tools: bpftool: preserve JSON output on errors on batch file parsing")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Print a "null" JSON object to standard output when bpftool is used to
print program instructions to a file, so as to avoid breaking JSON
output on batch mode.
This null object was added for most commands in a previous commit, but
this specific case had been omitted.
Fixes: 004b45c0e5 ("tools: bpftool: provide JSON output for all possible commands")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add bash completion for "bpftool cgroup" command family. While at it,
also fix the formatting of some keywords in the man page for cgroups.
Fixes: 5ccda64d38 ("bpftool: implement cgroup bpf operations")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add bash completion for bpftool command `prog load`. Completion for this
command is easy, as it only takes existing file paths as arguments.
Fixes: 49a086c201 ("bpftool: implement prog load command")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Specify in the documentation that when using bpftool to update a map of
type BPF_MAP_TYPE_PROG_ARRAY, the syntax for the program used as a value
should use the "id|tag|pinned" keywords convention, as used with
"bpftool prog" commands.
Fixes: ff69c21a85 ("tools: bpftool: add documentation")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
If rst2man is not available on the system, running `make doc` from the
bpftool directory fails with an error message. However, it creates empty
manual pages (.8 files in this case). A subsequent call to `make
doc-install` would then succeed and install those empty man pages on the
system.
To prevent this, raise a Makefile error and exit immediately if rst2man
is not available before generating the pages from the rst documentation.
Fixes: ff69c21a85 ("tools: bpftool: add documentation")
Reported-by: Jason van Aaardt <jason.vanaardt@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add BPF_MAP_TYPE_CPUMAP map type to the list
of map type recognized by bpftool and define
corresponding text representation.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Acked-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Print the information about device on which map is created.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
There is a static checker warning that "proglen" has an upper bound but
no lower bound. The allocation will just fail harmlessly so it's not a
big deal.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The current architecture detection method in bpftool is designed for host
case.
For offload case, we can't use the architecture of "bpftool" itself.
Instead, we could call the existing "ifindex_to_name_ns" to get DEVNAME,
then read pci id from /sys/class/dev/DEVNAME/device/vendor, finally we map
vendor id to bfd arch name which will finally be used to select bfd backend
for the disassembler.
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
bfd.h is requiring including of config.h except when PACKAGE or
PACKAGE_VERSION are defined.
/* PR 14072: Ensure that config.h is included first. */
#if !defined PACKAGE && !defined PACKAGE_VERSION
#error config.h must be included before this header
#endif
This check has been introduced since May-2012. It doesn't show up in bfd.h
on some Linux distribution, probably because distributions have remove it
when building the package.
However, sometimes the user might just build libfd from source code then
link bpftool against it. For this case, bfd.h will be original that we need
to define PACKAGE or PACKAGE_VERSION.
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Bpftool doesn't recognize BPF_PROG_TYPE_CGROUP_DEVICE programs,
so the prog show command prints the numeric type value:
$ bpftool prog show
1: type 15 name bpf_prog1 tag ac9f93dbfd6d9b74
loaded_at Jan 15/07:58 uid 0
xlated 96B jited 105B memlock 4096B
This patch defines the corresponding textual representation:
$ bpftool prog show
1: cgroup_device name bpf_prog1 tag ac9f93dbfd6d9b74
loaded_at Jan 15/07:58 uid 0
xlated 96B jited 105B memlock 4096B
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
It's a little bit unusual for kernel style, but we add the new line
character to error strings inside the p_err() function. We do this
because new lines at the end of error strings will break JSON output.
Fix a few p_err("..\n") which snuck in recently.
Fixes: 5ccda64d38 ("bpftool: implement cgroup bpf operations")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
iproute2 seems to accept show and list as aliases.
Let's do the same thing, and by allowing both bring
cgroup syntax back in line with maps and progs.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
So far we have used "show" as a keyword for listing
programs and maps. Use the word "show" in the code
for cgroups too, next commit will alias show and list.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Print the just-exposed device information about device to which
program is bound.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Bpftool build is broken with binutils version 2.29 and later.
The cause is commit 003ca0fd2286 ("Refactor disassembler selection")
in the binutils repo, which changed the disassembler() function
signature.
Fix this by adding a new "feature" to the tools/build/features
infrastructure and make it responsible for decision which
disassembler() function signature to use.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Bpftool determines it's own version based on the kernel
version, which is picked from the linux/version.h header.
It's strange to use the version of the installed kernel
headers, and makes much more sense to use the version
of the actual source tree, where bpftool sources are.
Fix this by building kernelversion target and use
the resulting string as bpftool version.
Example:
before:
$ bpftool version
bpftool v4.14.6
after:
$ bpftool version
bpftool v4.15.0-rc3
$bpftool version --json
{"version":"4.15.0-rc3"}
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
net/ipv6/ip6_gre.c is a case of parallel adds.
include/trace/events/tcp.h is a little bit more tricky. The removal
of in-trace-macro ifdefs in 'net' paralleled with moving
show_tcp_state_name and friends over to include/trace/events/sock.h
in 'net-next'.
Signed-off-by: David S. Miller <davem@davemloft.net>
On program/map show we may get an ID of an object from GETNEXT,
but the object may disappear before we call GET_FD_BY_ID. If
that happens, ignore the object and continue.
Fixes: 71bb428fe2 ("tools: bpf: add bpftool")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
We can't return from the middle of do_show(), because
json_array will not be closed. Break out of the loop.
Note that the error handling after the loop depends on
errno, so no need to set err.
Fixes: 831a0aafe5 ("tools: bpftool: add JSON output for `bpftool map *` commands")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch adds basic cgroup bpf operations to bpftool:
cgroup list, attach and detach commands.
Usage is described in the corresponding man pages,
and examples are provided.
Syntax:
$ bpftool cgroup list CGROUP
$ bpftool cgroup attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]
$ bpftool cgroup detach CGROUP ATTACH_TYPE PROG
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add the prog load command to load a bpf program from a specified
binary file and pin it to bpffs.
Usage description and examples are given in the corresponding man
page.
Syntax:
$ bpftool prog load OBJ FILE
FILE is a non-existing file on bpffs.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Create two targets to remove executable and documentation that would
have been previously installed with `make install` and `make
doc-install`.
Also create a "QUIET_UNINST" helper in tools/scripts/Makefile.include.
Do not attempt to remove directories /usr/local/sbin and
/usr/share/bash-completions/completions, even if they are empty, as
those specific directories probably already existed on the system before
we installed the program, and we do not wish to break other makefiles
that might assume their existence. Do remvoe /usr/local/share/man/man8
if empty however, as this directory does not seem to exist by default.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Several minor fixes and harmonisation items for Makefiles:
* Use the same mechanism for verbose/non-verbose output in two files
("$(Q)"), for all commands.
* Use calls to "QUIET_INSTALL" and equivalent in Makefile. In
particular, use "call(descend, ...)" instead of "make -C" to run
documentation targets.
* Add a "doc-clean" target, aligned on "doc" and "doc-install".
* Make "install" target in Makefile depend on "bpftool".
* Remove condition on DESTDIR to initialise prefix in doc Makefile.
* Remove modification of VPATH based on OUTPUT, it is unused.
* Formatting: harmonise spaces around equal signs.
* Make install path for man pages /usr/local/man instead of
/usr/local/share/man (respects the Makefile conventions, and the
latter is usually a symbolic link to the former anyway).
* Do not erase prefix if set by user in bpftool Makefile.
* Fix install target for bpftool: append DESTDIR to install path.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
In the Makefile, targets install, doc and doc-install should be added to
.PHONY. Let's fix this.
Fixes: 71bb428fe2 ("tools: bpf: add bpftool")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Programs and documentation not managed by package manager are generally
installed under /usr/local/, instead of the user's home directory. In
particular, `man` is generally able to find manual pages under
`/usr/local/share/man`.
bpftool generally follows perf's example, and perf installs to home
directory. However bpftool requires root credentials, so it seems
sensible to follow the more common convention of installing files under
/usr/local instead. So, make /usr/local the default prefix for
installing the binary with `make install`, and the documentation with
`make doc-install`. Also, create /usr/local/sbin if it does not exist.
Note that the bash-completion file, however, is still installed under
/usr/share/bash-completion/completions, as the default setup for bash
does not attempt to load completion files under /usr/local/.
Reported-by: David Beckett <david.beckett@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The end-of-line character inside the string would break JSON compliance.
Remove it, `p_err()` already adds a '\n' character for plain output
anyway.
Fixes: 9a5ab8bf1d ("tools: bpftool: turn err() and info() macros into functions")
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
If `getopt_long()` meets an unknown option, it prints its own error
message to standard error output. While this does not strictly break
JSON output, it is the only case bpftool prints something to standard
error output if JSON output is required. All other errors are printed on
standard output as JSON objects, so that an external program does not
have to parse stderr.
This is changed by setting the global variable `opterr` to 0.
Furthermore, p_err() is used to reproduce the error message in a more
JSON-friendly way, so that users still get to know what the erroneous
option is.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The writer is cleaned at the end of the main function, but not if the
program exits sooner in usage(). Let's keep it clean and destroy the
writer before exiting.
Destruction and actual call to exit() are moved to another function so
that clean exit can also be performed without printing usage() hints.
Fixes: d35efba99d ("tools: bpftool: introduce --json and --pretty options")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
If bad or unrecognised parameters are specified after JSON output is
requested, `usage()` will try to output null JSON object before the
writer is created.
To prevent this, create the writer as soon as the `--json` option is
parsed.
Fixes: 004b45c0e5 ("tools: bpftool: provide JSON output for all possible commands")
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This reverts commit 928631e054 ("bpftool: print program device bound
info"). We will remove this API and redo it right in -next.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Making it optional to show file names of pinned objects because
it scans complete bpf-fs filesystem which is costly.
Added option -f|--bpffs. Documentation updated.
Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
This was needed for opening any file in bpf-fs without knowing
its object type
Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
The two functions were declared as static inline in a header file. There
is no particular reason why they should be inlined, they just happened to
remain in the same header file when they were turned from macros to
functions in a precious commit.
Make them non-inlined functions and move them to common.c file instead.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
If program is bound to a device, print the name of the relevant
interface or unknown if the netdev has since been removed.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Files removed in 'net-next' had their license header updated
in 'net'. We take the remove from 'net-next'.
Signed-off-by: David S. Miller <davem@davemloft.net>
Use PATH_MAX instead of hardcoded array size 256
Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a completion file for bash. The completion function runs bpftool
when needed, making it smart enough to help users complete ids or tags
for eBPF programs and maps currently on the system.
Update Makefile to install completion file to
/usr/share/bash-completion/completions when running `make install`.
Emacs file mode and (at the end) Vim modeline have been added, to keep
the style in use for most existing bash completion files. In this, it
differs from tools/perf/perf-completion.sh, which seems to be the only
other completion file among the kernel sources repository. This is also
valid for indent style: 4-space indents, as in other completion files.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
One possible cause of failure for `bpftool {prog|map} pin * file FILE`
is the FILE not being in an eBPF virtual file system (bpffs). In this
case, make bpftool attempt to mount bpffs on the parent directory of the
FILE. Then, if this operation is successful, try again to pin the
object.
The code for mnt_bpffs() is a copy of function bpf_mnt_fs() from
iproute2 package (under lib/bpf.c, taken at commit 4b73d52f8a81), with
modifications regarding handling of error messages.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Update the documentation to provide help about JSON output generation,
and add an example in bpftool-prog manual page.
Also reintroduce an example that was left aside when the tool was moved
from GitHub to the kernel sources, in order to show how to mount the
bpffs file system (to pin programs) inside the bpftool-prog manual page.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Make the look-and-feel of the manual pages somewhat closer to other
manual pages, such as the ones from the utilities from iproute2, by
highlighting more keywords.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
As all commands can now return JSON output (possibly just a "null"
value), output of `bpftool --json batch file FILE` should also be fully
JSON compliant.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Turn err() and info() macros into functions.
In order to avoid naming conflicts with variables in the code, rename
them as p_err() and p_info() respectively.
The behavior of these functions is similar to the one of the macros for
plain output. However, when JSON output is requested, these macros
return a JSON-formatted "error" object instead of printing a message to
stderr.
To handle error messages correctly with JSON, a modification was brought
to their behavior nonetheless: the functions now append a end-of-line
character at the end of the message. This way, we can remove end-of-line
characters at the end of the argument strings, and not have them in the
JSON output.
All error messages are formatted to hold in a single call to p_err(), in
order to produce a single JSON field.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
`bpftool batch file FILE` takes FILE as an argument and executes all the
bpftool commands it finds inside (or stops if an error occurs).
To obtain a consistent JSON output, create a root JSON array, then for
each command create a new object containing two fields: one with the
command arguments, the other with the output (which is the JSON object
that the command would have produced, if called on its own).
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reuse the json_writer API introduced in an earlier commit to make
bpftool able to generate JSON output on
`bpftool map { show | dump | lookup | getnext }` commands. Remaining
commands produce no output.
Some functions have been spit into plain-output and JSON versions in
order to remain readable.
Outputs for sample maps have been successfully tested against a JSON
validator.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reuse the json_writer API introduced in an earlier commit to make
bpftool able to generate JSON output on `bpftool prog show *` commands.
A new printing function is created to be passed as an argument to the
disassembler.
Similarly to plain output, opcodes are printed on request.
Outputs from sample programs have been successfully tested against a
JSON validator.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
