Fix 32-bit arch and compat support for the kprobe_multi attach type

As suggested in [1], the kprobe_multi interface is to be fixed for 32-bit architectures and compat, rather then disabled. As it turned out, there are a couple of additional problems that are to be addressed:
- the absence of size overflow checks, leading to possible out-of-bounds writes (addressed by the first patch);
- the assumption that long has the same size as u64, which would make cookies arrays size calculation incorrect on 32-bit architectures (addressed by the second patch);
- the addrs array passing API, that is incompatible with compat and has to be changed (addressed in the fourth patch): those are kernel addresses and not user ones (as was incorrectly stated in [2]); this change is only semantical for 64-bit user/kernelspace, so it shouldn't impact ABI there, at least.

[1] https://lore.kernel.org/lkml/CAADnVQ+2gwhcMht4PuDnDOFKY68Wsq8QFz4Y69NBX_TLaSexQQ@mail.gmail.com/
[2] https://lore.kernel.org/lkml/[email protected]/

v2:
- Fixed the isses reported by CI

v1: https://lore.kernel.org/lkml/[email protected]/

Eugene Syromiatnikov (4):
bpf_trace: check size for overflow in bpf_kprobe_multi_link_attach
bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach
bpf_trace: handle compat in kprobe_multi_resolve_syms
bpf_trace: pass array of u64 values in kprobe_multi.addrs

 kernel/trace/bpf_trace.c                           | 62 ++++++++++++++++------
 tools/lib/bpf/bpf.h                                |  2 +-
 tools/lib/bpf/libbpf.c                             |  8 +--
 tools/lib/bpf/libbpf.h                             |  2 +-
 .../testing/selftests/bpf/prog_tests/bpf_cookie.c  |  2 +-
 .../selftests/bpf/prog_tests/kprobe_multi_test.c   |  8 +--
 6 files changed, 56 insertions(+), 28 deletions(-)

2.1.4