libbpf: Hashmap interface update to allow both long and void* keys/values

An update for libbpf's hashmap interface from void* -> void* to a
polymorphic one, allowing both long and void* keys and values.

This simplifies many use cases in libbpf as hashmaps there are mostly
integer to integer.

Perf copies hashmap implementation from libbpf and has to be
updated as well.

Changes to libbpf, selftests/bpf and perf are packed as a single
commit to avoid compilation issues with any future bisect.

Polymorphic interface is acheived by hiding hashmap interface
functions behind auxiliary macros that take care of necessary
type casts, for example:

#define hashmap_cast_ptr(p) \
({ \
_Static_assert((p) == NULL || sizeof(*(p)) == sizeof(long),\
#p " pointee should be a long-sized integer or a pointer"); \
(long *)(p); \
})

bool hashmap_find(const struct hashmap *map, long key, long *value);

#define hashmap__find(map, key, value) \
hashmap_find((map), (long)(key), hashmap_cast_ptr(value))

- hashmap__find macro casts key and value parameters to long
and long* respectively
- hashmap_cast_ptr ensures that value pointer points to a memory
of appropriate size.

This hack was suggested by Andrii Nakryiko in [1].
This is a follow up for [2].

[1] https://lore.kernel.org/bpf/CAEf4BzZ8KFneEJxFAaNCCFPGqp20hSpS2aCj76uRk3-qZUH5xg@mail.gmail.com/
[2] https://lore.kernel.org/bpf/af1facf9-7bc8-8a3d-0db4-7b3f333589a2@meta.com/T/#m65b28f1d6d969fcd318b556db6a3ad499a42607d

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221109142611.879983-2-eddyz87@gmail.com

selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks

Turn ony libbpf 1.0 mode. Fix all the explicit IS_ERR checks that now will be
broken because libbpf returns NULL on error (and sets errno). Fix
ASSERT_OK_PTR and ASSERT_ERR_PTR to work for both old mode and new modes and
use them throughout selftests. This is trivial to do by using
libbpf_get_error() API that all libbpf users are supposed to use, instead of
IS_ERR checks.

A bunch of checks also did explicit -1 comparison for various fd-returning
APIs. Such checks are replaced with >= 0 or < 0 cases.

There were also few misuses of bpf_object__find_map_by_name() in test_maps.
Those are fixed in this patch as well.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210525035935.1461796-3-andrii@kernel.org

selftests/bpf: Convert test_hashmap into test_progs test

Fold stand-alone test_hashmap test into test_progs.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200429012111.277390-4-andriin@fb.com