selftests/bpf: Clean up sys_nanosleep uses

This patch cleans up a few things:

* dynptr_fail.c:
There is no sys_nanosleep tracepoint. dynptr_fail only tests
that the prog load fails, so just SEC("?raw_tp") suffices here.

* test_bpf_cookie:
There is no sys_nanosleep kprobe. The prog is loaded in
userspace through bpf_program__attach_kprobe_opts passing in
SYS_NANOSLEEP_KPROBE_NAME, so just SEC("k{ret}probe") suffices here.

* test_helper_restricted:
There is no sys_nanosleep kprobe. test_helper_restricted only tests
that the prog load fails, so just SEC("?kprobe")( suffices here.

There are no functional changes.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220805171405.2272103-1-joannelkoong@gmail.com

selftest/bpf: The test cases of BPF cookie for fentry/fexit/fmod_ret/lsm.

Make sure BPF cookies are correct for fentry/fexit/fmod_ret/lsm.

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220510205923.3206889-6-kuifeng@fb.com

libbpf: Add auto-attach for uprobes based on section name

Now that u[ret]probes can use name-based specification, it makes
sense to add support for auto-attach based on SEC() definition.
The format proposed is

SEC("u[ret]probe/binary:[raw_offset|[function_name[+offset]]")

For example, to trace malloc() in libc:

SEC("uprobe/libc.so.6:malloc")

...or to trace function foo2 in /usr/bin/foo:

SEC("uprobe//usr/bin/foo:foo2")

Auto-attach is done for all tasks (pid -1). prog can be an absolute
path or simply a program/library name; in the latter case, we use
PATH/LD_LIBRARY_PATH to resolve the full path, falling back to
standard locations (/usr/bin:/usr/sbin or /usr/lib64:/usr/lib) if
the file is not found via environment-variable specified locations.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1648654000-21758-4-git-send-email-alan.maguire@oracle.com

selftests/bpf: Add bpf_cookie selftests for high-level APIs

Add selftest with few subtests testing proper bpf_cookie usage.

Kprobe and uprobe subtests are pretty straightforward and just validate that
the same BPF program attached with different bpf_cookie will be triggered with
those different bpf_cookie values.

Tracepoint subtest is a bit more interesting, as it is the only
perf_event-based BPF hook that shares bpf_prog_array between multiple
perf_events internally. This means that the same BPF program can't be attached
to the same tracepoint multiple times. So we have 3 identical copies. This
arrangement allows to test bpf_prog_array_copy()'s handling of bpf_prog_array
list manipulation logic when programs are attached and detached. The test
validates that bpf_cookie isn't mixed up and isn't lost during such list
manipulations.

Perf_event subtest validates that two BPF links can be created against the
same perf_event (but not at the same time, only one BPF program can be
attached to perf_event itself), and that for each we can specify different
bpf_cookie value.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-15-andrii@kernel.org