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: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid 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: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid 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: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a new printing function to dump translated eBPF instructions as
JSON. As for plain output, opcodes are printed only on request (when
`opcodes` is provided on the command line).

The disassembled output is generated by the same code that is used by
the kernel verifier.

Example output:

    $ bpftool --json --pretty prog dump xlated id 1
    [{
            "disasm": "(bf) r6 = r1"
        },{
            "disasm": "(61) r7 = *(u32 *)(r6 +16)"
        },{
            "disasm": "(95) exit"
        }
    ]

    $ bpftool --json --pretty prog dump xlated id 1 opcodes
    [{
            "disasm": "(bf) r6 = r1",
            "opcodes": {
                "code": "0xbf",
                "src_reg": "0x1",
                "dst_reg": "0x6",
                "off": ["0x00","0x00"
                ],
                "imm": ["0x00","0x00","0x00","0x00"
                ]
            }
        },{
            "disasm": "(61) r7 = *(u32 *)(r6 +16)",
            "opcodes": {
                "code": "0x61",
                "src_reg": "0x6",
                "dst_reg": "0x7",
                "off": ["0x10","0x00"
                ],
                "imm": ["0x00","0x00","0x00","0x00"
                ]
            }
        },{
            "disasm": "(95) exit",
            "opcodes": {
                "code": "0x95",
                "src_reg": "0x0",
                "dst_reg": "0x0",
                "off": ["0x00","0x00"
                ],
                "imm": ["0x00","0x00","0x00","0x00"
                ]
            }
        }
    ]
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid 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.

For readability, the code from show_prog() has been split into two
functions, one for plain output, one for JSON.

Outputs from sample programs have been successfully tested against a
JSON validator.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For the `bpftool prog dump { jited | xlated } ...` command, adding
`opcodes` keyword (to request opcodes to be printed) will have no effect
if `file FILE` (to write binary output to FILE) is provided.

The manual page and the help message to be displayed in the terminal
should reflect that, and indicate that these options should be mutually
exclusive.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The eBPF instruction permitting to load double words (8 bytes) into a
register need 8-byte long "immediate" field, and thus occupy twice the
space of other instructions. bpftool was aware of this and would
increment the instruction counter only once on meeting such instruction,
but it would only print the first four bytes of the immediate value to
load. Make it able to dump the whole 16 byte-long double instruction
instead (as would `llvm-objdump -d <program>`).
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make error messages and return codes more consistent. Specifically, make
`bpftool prog help` a real command, instead of printing usage by default
for a non-recognized "help" command. Output is the same, but this makes
bpftool return with a success value instead of an error.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make error messages and return codes more consistent. Specifically,
replace the use of info() macro with err() when too many eBPF
instructions are received to be dumped, given that bpftool returns with
a non-null exit value in that case.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Change the program to have a more consistent return code. Specifically,
do not make bpftool return an error code simply because it reaches the
end of the list of the eBPF programs to show.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make print_hex() able to print to any file instead of standard output
only, and rename it to fprint_hex(). The function can now be called with
the info() macro, for example, without splitting the output between
standard and error outputs.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Program tag is usually displayed as string of bytes without
any separators (e.g. as "aa5520b1090cfeb6" vs MAC addr-like
format bpftool uses currently: "aa:55:20:b1:09:0c:fe:b6").
Make bptfool use the more common format both for displaying
the tag and selecting the program by tag.

This was pointed out in review but I misunderstood the comment.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Compile the instruction printer from kernel/bpf and use it
for disassembling "translated" eBPF code.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a simple tool for querying and updating BPF objects on the system.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>