samples/bpf: Relicense bpf_insn.h as GPL-2.0-only OR BSD-2-Clause

libbpf and bpftool have been dual-licensed to facilitate inclusion in software
that is not compatible with GPL2-only (ie: Apache2), but the samples are still
GPL2-only.

Given these files are samples, they get naturally copied around. For example,
it is the case for samples/bpf/bpf_insn.h which was copied into the systemd
tree: https://github.com/systemd/systemd/blob/main/src/shared/linux/bpf_insn.h

Some more context on systemd's needs specifically:

Most of systemd is (L)GPL2-or-later, which means there is no perceived
incompatibility with Apache2 software and can thus be linked with
OpenSSL 3.0. But given this GPL2-only header is included this is currently
not possible. Dual-licensing this header solves this problem for us as we
are scoping a move to OpenSSL 3.0, see:

https://lists.freedesktop.org/archives/systemd-devel/2021-September/046882.html

Dual-license this header as GPL-2.0-only OR BSD-2-Clause to follow the same
licensing used by libbpf and bpftool:

1bc38b8ff6cc ("libbpf: relicense libbpf as LGPL-2.1 OR BSD-2-Clause")
907b22365115 ("tools: bpftool: dual license all files")

Signed-off-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Daniel Mack <daniel@zonque.org>
Acked-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Joe Stringer <joe@ovn.org>
Acked-by: Chenbo Feng <fengc@google.com>
Acked-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Brendan Jackman <jackmanb@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210923000540.47344-1-luca.boccassi@gmail.com

samples/bpf: Add BPF_ATOMIC_OP macro for BPF samples

Brendan Jackman added extend atomic operations to the BPF instruction
set in commit 7064a7341a0d ("Merge branch 'Atomics for eBPF'"), which
introduces the BPF_ATOMIC_OP macro. However, that macro was missing
for the BPF samples. Fix that by adding it into bpf_insn.h.

Fixes: 91c960b00566 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20210118091753.107572-1-bjorn.topel@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: Rename BPF_XADD and prepare to encode other atomics in .imm

A subsequent patch will add additional atomic operations. These new
operations will use the same opcode field as the existing XADD, with
the immediate discriminating different operations.

In preparation, rename the instruction mode BPF_ATOMIC and start
calling the zero immediate BPF_ADD.

This is possible (doesn't break existing valid BPF progs) because the
immediate field is currently reserved MBZ and BPF_ADD is zero.

All uses are removed from the tree but the BPF_XADD definition is
kept around to avoid breaking builds for people including kernel
headers.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-5-jackmanb@google.com

selftests: bpf: functional and min/max reasoning unit tests for JMP32

This patch adds unit tests for new JMP32 instructions.

This patch also added the new BPF_JMP32_REG and BPF_JMP32_IMM macros to
samples/bpf/bpf_insn.h so that JMP32 insn builders are available to tests
under 'samples' directory.

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples: bpf: rename libbpf.h to bpf_insn.h

The libbpf.h file in samples is clashing with libbpf's header.
Since it only includes a subset of filter.h instruction helpers
rename it to bpf_insn.h. Drop the unnecessary include of bpf/bpf.h.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>