mbox series

[v2,bpf-next,0/3] Add support for memory-mapping BPF array maps

Message ID 20191109080633.2855561-1-andriin@fb.com
Headers show
Series Add support for memory-mapping BPF array maps | expand

Message

Andrii Nakryiko Nov. 9, 2019, 8:06 a.m. UTC 
This patch set adds ability to memory-map BPF array maps (single- and
multi-element). The primary use case is memory-mapping BPF array maps, created
to back global data variables, created by libbpf implicitly. This allows for
much better usability, along with avoiding syscalls to read or update data
completely.

Due to memory-mapping requirements, BPF array map that is supposed to be
memory-mapped, has to be created with special BPF_F_MMAPABLE attribute, which
triggers slightly different memory allocation strategy internally. See
patch 1 for details.

Libbpf is extended to detect kernel support for this flag, and if supported,
will specify it for all global data maps automatically.

v1->v2:
- fix map lookup code generation for BPF_F_MMAPABLE case;
- prevent BPF_F_MMAPABLE flag for all but plain array map type;
- centralize ref-counting in generic bpf_map_mmap();
- don't use uref counting (Alexei);
- use vfree() directly;
- print flags with %x (Song);
- extend tests to verify bpf_map_{lookup,update}_elem() logic as well.

Andrii Nakryiko (3):
  bpf: add mmap() support for BPF_MAP_TYPE_ARRAY
  libbpf: make global data internal arrays mmap()-able, if possible
  selftests/bpf: add BPF_TYPE_MAP_ARRAY mmap() tests

 include/linux/bpf.h                           |   9 +-
 include/uapi/linux/bpf.h                      |   3 +
 kernel/bpf/arraymap.c                         | 111 ++++++++++--
 kernel/bpf/syscall.c                          |  47 +++++
 tools/include/uapi/linux/bpf.h                |   3 +
 tools/lib/bpf/libbpf.c                        |  31 +++-
 .../selftests/bpf/prog_tests/core_reloc.c     |  45 +++--
 tools/testing/selftests/bpf/prog_tests/mmap.c | 170 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/test_mmap.c |  41 +++++
 9 files changed, 426 insertions(+), 34 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/mmap.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_mmap.c