bpf: Abstract loop unrolling pragmas in BPF selftests

[Changes from V1:
- Avoid conflict by rebasing with latest master.]

Some BPF tests use loop unrolling compiler pragmas that are clang
specific and not supported by GCC. These pragmas, along with their
GCC equivalences are:

#pragma clang loop unroll_count(N)
#pragma GCC unroll N

#pragma clang loop unroll(full)
#pragma GCC unroll 65534

#pragma clang loop unroll(disable)
#pragma GCC unroll 1

#pragma unroll [aka #pragma clang loop unroll(enable)]
There is no GCC equivalence to this pragma. It enables unrolling on
loops that the compiler would not ordinarily unroll even with
-O2|-funroll-loops, but it is not equivalent to full unrolling
either.

This patch adds a new header progs/bpf_compiler.h that defines the
following macros, which correspond to each pair of compiler-specific
pragmas above:

__pragma_loop_unroll_count(N)
__pragma_loop_unroll_full
__pragma_loop_no_unroll
__pragma_loop_unroll

The selftests using loop unrolling pragmas are then changed to include
the header and use these macros in place of the explicit pragmas.

Tested in bpf-next master.
No regressions.

Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240208203612.29611-1-jose.marchesi@oracle.com

selftests/bpf: Define string const as global for test_sysctl_prog.c

When tweaking llvm optimizations, I found that selftest build failed
with the following error:
libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1
libbpf: prog 'sysctl_tcp_mem': bad map relo against '.L__const.is_tcp_mem.tcp_mem_name'
in section '.rodata.str1.1'
Error: failed to open BPF object file: Relocation failed
make: *** [/work/net-next/tools/testing/selftests/bpf/test_sysctl_prog.skel.h] Error 255
make: *** Deleting file `/work/net-next/tools/testing/selftests/bpf/test_sysctl_prog.skel.h'

The local string constant "tcp_mem_name" is put into '.rodata.str1.1' section
which libbpf cannot handle. Using untweaked upstream llvm, "tcp_mem_name"
is completely inlined after loop unrolling.

Commit 7fb5eefd7639 ("selftests/bpf: Fix test_sysctl_loop{1, 2}
failure due to clang change") solved a similar problem by defining
the string const as a global. Let us do the same here
for test_sysctl_prog.c so it can weather future potential llvm changes.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910202718.956042-1-yhs@fb.com

selftests/bpf: fix test_sysctl_prog with alu32

Similar to commit b7a0d65d80a0 ("bpf, testing: Workaround a verifier failure for test_progs")
fix test_sysctl_prog.c as well.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests: Use consistent include paths for libbpf

Fix all selftests to include libbpf header files with the bpf/ prefix, to
be consistent with external users of the library. Also ensure that all
includes of exported libbpf header files (those that are exported on 'make
install' of the library) use bracketed includes instead of quoted.

To not break the build, keep the old include path until everything has been
changed to the new one; a subsequent patch will remove that.

Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157952560568.1683545.9649335788846513446.stgit@toke.dk

selftests/bpf: remove bpf_util.h from BPF C progs

Though currently there is no problem including bpf_util.h in kernel
space BPF C programs, in next patch in this stack, I will reuse
libbpf_num_possible_cpus() in bpf_util.h thus include libbpf.h in it,
which will cause BPF C programs compile error. Therefore I will first
remove bpf_util.h from all test BPF programs.

This can also make it clear that bpf_util.h is a user-space utility
while bpf_helpers.h is a kernel space utility.

Signed-off-by: Hechao Li <hechaol@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

selftests/bpf: C based test for sysctl and strtoX

Add C based test for a few bpf_sysctl_* helpers and bpf_strtoul.

Make sure that sysctl can be identified by name and that multiple
integers can be parsed from sysctl value with bpf_strtoul.

net/ipv4/tcp_mem is chosen as a testing sysctl, it contains 3 unsigned
longs, they all are parsed and compared (val[0] < val[1] < val[2]).

Example of output:
# ./test_sysctl
...
Test case: C prog: deny all writes .. [PASS]
Test case: C prog: deny access by name .. [PASS]
Test case: C prog: read tcp_mem .. [PASS]
Summary: 39 PASSED, 0 FAILED

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>