pkgconfig: use literal ${prefix} to allow override

Various workflows (--define-prefix, --define-variable=prefix) require variables in
the pc file to use a literal  so that it is overridden. Change the Makefile
so that, by default and unless  is specified, it is set as expected.

Signed-off-by: Luca Boccassi <bluca@debian.org>

helpers: add `struct bpf_redir_neigh` forward declaration

This avoids compilation warning if `struct bpf_redir_neigh` is not provided by
other kernel headers.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

libbpf: Fix XDP program load regression for old kernels

Fix regression in libbpf, introduced by XDP link change, which causes XDP
programs to fail to be loaded into kernel due to specified BPF_XDP
expected_attach_type. While kernel doesn't enforce expected_attach_type for
BPF_PROG_TYPE_XDP, some old kernels already support XDP program, but they
don't yet recognize expected_attach_type field in bpf_attr, so setting it to
non-zero value causes program load to fail.

Luckily, libbpf already has a mechanism to deal with such cases, so just make
expected_attach_type optional for XDP programs.

Fixes: dc8698cac7aa ("libbpf: Add support for BPF XDP link")
Reported-by: Nikita Shirokov <tehnerd@tehnerd.com>
Reported-by: Udip Pant <udippant@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200924171705.3803628-1-andriin@fb.com
(cherry picked from commit 2200fef)

vmtests: fix selftests checkout script

Fix the script.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>

sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   69119673bd50b176ded34032fadd41530fb5af21
Checkpoint bpf-next commit: 4e15507fea70c0c312d79610efa46b6853ccf8e0
Baseline bpf commit:        6903cdae9f9f08d61e49c16cbef11c293e33a615
Checkpoint bpf commit:      4e15507fea70c0c312d79610efa46b6853ccf8e0

Andrii Nakryiko (1):
  libbpf: Forward-declare bpf_stats_type for systems with outdated UAPI
    headers

 src/bpf.h | 2 ++
 1 file changed, 2 insertions(+)

--
2.24.1

vmtests: blacklist mmap test on 5.5

5.5 kernel has a bug in kernel allowing to violate read-only access to
mmap()-ed map. Disable selftest that now is failing.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>

vmtest: build and run bpf kernel selftests against various kernels

Run kernel selftests in vmtest with the goal to test libbpf backward
compatibility with older kernels.
The list of kernels should be specified in .travis.yml config in
`jobs` section, e.g. KERNEL=5.5.0.
Enlisted kernel releases
- 5.5.0 # built from main
- 5.5.0-rc6 # built from bpf-next
- LATEST

The kernel specified as 'LATEST' in .travis.yml is built from bpf-next kernel
tree, the rest of the kernels are downloaded from the specified in INDEX file.
The kernel sources from bpf-next are manually patched with [1] from bpf tree to
fix ranqslower build. This workaround should be removed after the patch is merged
from bpf to bpf-next tree.
Due to kernel sources being checked out the duration of the LATEST kernel test is
~30m.

bpf selftests are built from tools/testing/selftests/bpf/ of bpf-next tree with
HEAD revision set to CHECKPOINT-COMMIT specified in libbpf so selftests and
libbpf are in sync.
Currently only programs are tested with test_progs program, test_maps and
test_verifier should follow.
test_progs are run with blacklist required due to:
- some features, e.g. fentry/fexit are not supported in older kernels
- environment limitations, e.g an absence of the recent pahole in Debian
- incomplete disk image

The blacklist is passed to test_progs with -b option as specified in [2]
patch set.

Most of the preceeding tests are disabled due to incomplete disk image currenly
lacking proper networking settings.
For the LATEST kernel fome fentry/fexit tests are disabled due to pahole v1.16
is not abailible in Debian yet.

Next steps are resolving issues with blacklisted tests, enabling maps and
verifier testing, expanding the list of tested kernels.

[1] https://lore.kernel.org/bpf/908498f794661c44dca54da9e09dc0c382df6fcb.1580425879.git.hex@fb.com/t.mbox.gz
[2] https://www.spinics.net/lists/netdev/msg625192.html

sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit:   b615e5a1e067dcb327482d1af7463268b89b1629
Checkpoint bpf-next commit: e7096c131e5161fa3b8e52a650d7719d2857adfd
Baseline bpf commit:        34e59836565e36fade1464e054a3551c1a0364be
Checkpoint bpf commit:      e42617b825f8073569da76dc4510bfa019b1c35a

Alexei Starovoitov (2):
  libbpf: Fix sym->st_value print on 32-bit arches
  selftests/bpf: Add test for BPF trampoline

Andrii Nakryiko (1):
  libbpf: Fix global variable relocation

Martin KaFai Lau (1):
  bpf: Introduce BPF_TRACE_x helper for the tracing tests

 src/libbpf.c | 45 ++++++++++++++++++++-------------------------
 1 file changed, 20 insertions(+), 25 deletions(-)

--
2.17.1

meson: kill meson.build as it's not used anymore

Meson.build was added to facilitate systemd integration, but systemd
integration went different direction and we don't need meson.build
anymore. So remove it and not maintain it anymore.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>

sync: latest libbpf changes from kernel

Syncing latest libbpf commits from kernel repository.
Baseline commit:   8fc9f8bedf1bdaea48382ae2e3dd558e2b939cee
Checkpoint commit: 66b5f1c439843bcbab01cc7f3854ae2742f3d1e3

Andrii Nakryiko (2):
  libbpf: fix ptr to u64 conversion warning on 32-bit platforms
  libbpf: fix another GCC8 warning for strncpy

Baruch Siach (1):
  bpf: fix uapi bpf_prog_info fields alignment

Mauro Carvalho Chehab (2):
  docs: cgroup-v1: convert docs to ReST and rename to *.rst
  docs: cgroup-v1: add it to the admin-guide book

Stanislav Fomichev (1):
  bpf: sync bpf.h to tools/

 include/uapi/linux/bpf.h | 7 ++++---
 src/libbpf.c             | 4 ++--
 src/xsk.c                | 3 ++-
 3 files changed, 8 insertions(+), 6 deletions(-)

--
2.17.1