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

perf tools: Update copy of libbpf's hashmap.c

To pick the changes in:

fba60b171a032283 ("libbpf: Use IS_ERR_OR_NULL() in hashmap__free()")

That don't entail any changes in tools/perf.

This addresses this perf build warning:

Warning: Kernel ABI header at 'tools/perf/util/hashmap.h' differs from latest version at 'tools/lib/bpf/hashmap.h'
diff -u tools/perf/util/hashmap.h tools/lib/bpf/hashmap.h

Not a kernel ABI, its just that this uses the mechanism in place for
checking kernel ABI files drift.

Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mauricio Vásquez <mauricio@kinvolk.io>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/YkMb2SAIai2VeuUD@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf tools: Update copy of libbpf's hashmap.c

To pick the changes in:

85367030a6c7ef33 ("libbpf: Centralize poisoning and poison reallocarray()")
7d9c71e10baa3496 ("libbpf: Extract generic string hashing function for reuse")

That don't entail any changes in tools/perf.

This addresses this perf build warning:

Warning: Kernel ABI header at 'tools/perf/util/hashmap.h' differs from latest version at 'tools/lib/bpf/hashmap.h'
diff -u tools/perf/util/hashmap.h tools/lib/bpf/hashmap.h

Not a kernel ABI, its just that this uses the mechanism in place for
checking kernel ABI files drift.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf tools: Grab a copy of libbpf's hashmap

Allow use of hashmap in perf. Modify perf's check-headers.sh script to
check that the files are kept in sync, in the same way kernel headers
are checked. This will warn if they are out of sync at the start of a
perf build.

Committer note:

This starts out of synch as a fix went thru the bpf tree, namely the one
removing the needless libbpf_internal.h include in hashmap.h.

There is also another change related to __WORDSIZE, that as is in
tools/lib/bpf/hashmap.h causes the tools/perf/ build to fail in systems
such as Alpine Linus, that uses the Musl libc, so we need an alternative
way of having __WORDSIZE available, use the one used by
tools/include/linux/bitops.h, that builds in all the systems I have
build containers for.

These differences will be resolved at some point, so keep the warning in
check-headers.sh as a reminder.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: kp singh <kpsingh@chromium.org>
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200515221732.44078-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>