Precise and non-ambiguous license information is important. The recent
relicensing of the bpftools introduced a license conflict.

The files have now:

     SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause

and

     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * as published by the Free Software Foundation; either version
     * 2 of the License, or (at your option) any later version

Amazingly about 20 people acked that change and neither they nor the
committer noticed. Oh well.

Digging deeper: The files were imported from the iproute2 repository with
the GPL V2 or later boiler plate text in commit b66e907cfee2 ("tools:
bpftool: copy JSON writer from iproute2 repository")

Looking at the iproute2 repository at

  git://git.kernel.org/pub/scm/network/iproute2/iproute2.git

the following commit is the equivivalent:

  commit d9d8c839 ("json_writer: add SPDX Identifier (GPL-2/BSD-2)")

That commit explicitly removes the boiler plate and relicenses the code
uner GPL-2.0-only and BSD-2-Clause. As Steven wrote the original code and
also the relicensing commit, it's assumed that the relicensing was intended
to do exaclty that. Just the kernel side update failed to remove the boiler
plate. Do so now.

Fixes: 907b22365115 ("tools: bpftool: dual license all files")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Sean Young <sean@mess.org>
Cc: Jiri Benc <jbenc@redhat.com>
Cc: David Calavera <david.calavera@gmail.com>
Cc: Andrey Ignatov <rdna@fb.com>
Cc: Joe Stringer <joe@wand.net.nz>
Cc: David Ahern <dsahern@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Petar Penkov <ppenkov@stanford.edu>
Cc: Sandipan Das <sandipan@linux.ibm.com>
Cc: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
CC: okash.khawaja@gmail.com
Cc: netdev@vger.kernel.org
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

On some platforms, in order to link against libbfd, we need to
link against liberty and even possibly libz. Account for that
in the bpftool Makefile. We now have proper feature detection
for each case, so handle each one separately.

See recent commit 14541b1e7e72 ("perf build: Don't unconditionally link the
libbfd feature test to -liberty and -lz") where I fixed feature
detection.

v2 (addressed Jakub's nits):
  * better syntax for 'else ifeq'
  * no space between ifeq args
v3:
  * use LIBS, not EXTLIBS for -DHAVE_LIBBFD_SUPPORT

Fixes: 29a9c10e4110 ("bpftool: make libbfd optional")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Commit 8772c8bc093b ("tools: bpftool: support pretty print
with kind_flag set") added bpftool map dump with kind_flag
support. When bitfield_size can be retrieved directly from
btf_member, function btf_dumper_bitfield() is called to
dump the bitfield. The implementation passed the
wrong parameter "bit_offset" to the function. The excepted
value is the bit_offset within a byte while the passed-in
value is the struct member offset.

This commit fixed the bug with passing correct "bit_offset"
with adjusted data pointer.

Fixes: 8772c8bc093b ("tools: bpftool: support pretty print with kind_flag set")
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This allows transparent cross-compilation with CROSS_COMPILE by
relying on 7ed1c1901fe5 ("tools: fix cross-compile var clobbering").

Signed-off-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

In order to make life easier for users, bpftool automatically attempts
to mount the BPF virtual file system, if it is not mounted already,
before trying to pin objects in it. Similarly, it attempts to mount
tracefs if necessary before trying to dump the trace pipe to the
console.

While mounting file systems on-the-fly can improve user experience, some
administrators might prefer to avoid that. Let's add an option to block
these mount attempts. Note that it does not prevent automatic mounting
of tracefs by debugfs for the "bpftool prog tracelog" 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>

As a follow-up to commit 30da46b5dc3a ("tools: bpftool: add a command to
dump the trace pipe"), attempt to mount the tracefs virtual file system
if it is not detected on the system before trying to dump content of the
tracing pipe on an invocation of "bpftool prog tracelog".

Usually, tracefs in automatically mounted by debugfs when the user tries
to access it (e.g. "ls /sys/kernel/debug/tracing" mounts the tracefs).
So if we failed to find it, it is probably that debugfs is not here
either. Therefore, we just attempt a single mount, at a location that
does not involve debugfs: /sys/kernel/tracing.

Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
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>

The following example shows map pretty print with structures
which include bitfield members.

  enum A { A1, A2, A3, A4, A5 };
  typedef enum A ___A;
  struct tmp_t {
       char a1:4;
       int  a2:4;
       int  :4;
       __u32 a3:4;
       int b;
       ___A b1:4;
       enum A b2:4;
  };
  struct bpf_map_def SEC("maps") tmpmap = {
       .type = BPF_MAP_TYPE_ARRAY,
       .key_size = sizeof(__u32),
       .value_size = sizeof(struct tmp_t),
       .max_entries = 1,
  };
  BPF_ANNOTATE_KV_PAIR(tmpmap, int, struct tmp_t);

and the following map update in the bpf program:

  key = 0;
  struct tmp_t t = {};
  t.a1 = 2;
  t.a2 = 4;
  t.a3 = 6;
  t.b = 7;
  t.b1 = 8;
  t.b2 = 10;
  bpf_map_update_elem(&tmpmap, &key, &t, 0);

With this patch, I am able to print out the map values
correctly with this patch:
bpftool map dump id 187
  [{
        "key": 0,
        "value": {
            "a1": 0x2,
            "a2": 0x4,
            "a3": 0x6,
            "b": 7,
            "b1": 0x8,
            "b2": 0xa
        }
    }
  ]

Previously, if a function prototype argument has a typedef
type, the prototype is not printed since
function __btf_dumper_type_only() bailed out with error
if the type is a typedef. This commit corrected this
behavior by printing out typedef properly.

The following example shows forward type and
typedef type can be properly printed in function prototype
with modified test_btf_haskv.c.

  struct t;
  union  u;

  __attribute__((noinline))
  static int test_long_fname_1(struct dummy_tracepoint_args *arg,
                               struct t *p1, union u *p2,
                               __u32 unused)
  ...
  int _dummy_tracepoint(struct dummy_tracepoint_args *arg) {
    return test_long_fname_1(arg, 0, 0, 0);
  }

  $ bpftool p d xlated id 24
  ...
  int test_long_fname_1(struct dummy_tracepoint_args * arg,
                        struct t * p1, union u * p2,
                        __u32 unused)
  ...

Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The core dump funcitonality in btf_dumper_int_bits() is
refactored into a separate function btf_dumper_bitfield()
which will be used by the next patch.

Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Help compiler check arguments for several utility functions used to
print items to the console by adding the "printf" attribute when
declaring those functions.

Also, declare as "static" two functions that are only used in prog.c.

All of them discovered by compiling bpftool with
-Wmissing-format-attribute -Wmissing-declarations.

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>

The following warning appears when compiling bpftool without BFD
support:

main.h:198:23: warning: 'struct bpf_prog_linfo' declared inside
    parameter list will not be visible outside of this definition or
    declaration
          const struct bpf_prog_linfo *prog_linfo,

Fix it by declaring struct bpf_prog_linfo even in the case BFD is not
supported.

Fixes: b053b439b72a ("bpf: libbpf: bpftool: Print bpf_line_info during prog dump")
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>