[bpf-next,v3,00/13] bpf: Add support for local percpu kptr

Message

Yonghong Song Aug. 27, 2023, 3:27 p.m. UTC

Patch set [1] implemented cgroup local storage BPF_MAP_TYPE_CGRP_STORAGE
similar to sk/task/inode local storage and old BPF_MAP_TYPE_CGROUP_STORAGE
map is marked as deprecated since old BPF_MAP_TYPE_CGROUP_STORAGE map can
only work with current cgroup.

Similarly, the existing BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE map
is a percpu version of BPF_MAP_TYPE_CGROUP_STORAGE and only works
with current cgroup. But there is no replacement which can work
with arbitrary cgroup.

This patch set solved this problem but adding support for local
percpu kptr. The map value can have a percpu kptr field which holds
a bpf prog allocated percpu data. The below is an example,

  struct percpu_val_t {
    ... fields ...
  }

  struct map_value_t {
    struct percpu_val_t __percpu_kptr *percpu_data_ptr;
  }

In the above, 'map_value_t' is the map value type for a
BPF_MAP_TYPE_CGRP_STORAGE map. User can access 'percpu_data_ptr'
and then read/write percpu data. This covers BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE
and more. So BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE map type
is marked as deprecated.

In additional, local percpu kptr supports the same map type
as other kptrs including hash, lru_hash, array, sk/inode/task/cgrp
local storage. Currently, percpu data structure does not support
non-scalars or special fields (e.g., bpf_spin_lock, bpf_rb_root, etc.).
They can be supported in the future if there exist use cases.

Please for individual patches for details.

  [1] https://lore.kernel.org/all/[e-mail]/

Changelog:
  v2 -> v3:
    - fix libbpf_str test failure.
  v1 -> v2:
    - does not support special fields in percpu data structure.
    - rename __percpu attr to __percpu_kptr attr.
    - rename BPF_KPTR_PERCPU_REF to BPF_KPTR_PERCPU.
    - better code to handle bpf_{this,per}_cpu_ptr() helpers.
    - add more negative tests.
    - fix a bpftool related test failure.

Yonghong Song (13):
  bpf: Add support for non-fix-size percpu mem allocation
  bpf: Add BPF_KPTR_PERCPU as a field type
  bpf: Add alloc/xchg/direct_access support for local percpu kptr
  bpf: Add bpf_this_cpu_ptr/bpf_per_cpu_ptr support for allocated percpu
    obj
  selftests/bpf: Update error message in negative linked_list test
  libbpf: Add __percpu_kptr macro definition
  selftests/bpf: Add bpf_percpu_obj_{new,drop}() macro in
    bpf_experimental.h
  selftests/bpf: Add tests for array map with local percpu kptr
  bpf: Mark OBJ_RELEASE argument as MEM_RCU when possible
  selftests/bpf: Remove unnecessary direct read of local percpu kptr
  selftests/bpf: Add tests for cgrp_local_storage with local percpu kptr
  selftests/bpf: Add some negative tests
  bpf: Mark BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE deprecated

 include/linux/bpf.h                           |  22 +-
 include/linux/bpf_verifier.h                  |   1 +
 include/uapi/linux/bpf.h                      |   9 +-
 kernel/bpf/btf.c                              |   5 +
 kernel/bpf/core.c                             |   8 +-
 kernel/bpf/helpers.c                          |  16 ++
 kernel/bpf/memalloc.c                         |  14 +-
 kernel/bpf/syscall.c                          |   4 +
 kernel/bpf/verifier.c                         | 191 +++++++++++++++---
 tools/include/uapi/linux/bpf.h                |   9 +-
 tools/lib/bpf/bpf_helpers.h                   |   1 +
 .../testing/selftests/bpf/bpf_experimental.h  |  31 +++
 .../selftests/bpf/prog_tests/libbpf_str.c     |   6 +-
 .../selftests/bpf/prog_tests/linked_list.c    |   4 +-
 .../selftests/bpf/prog_tests/percpu_alloc.c   | 125 ++++++++++++
 .../selftests/bpf/progs/percpu_alloc_array.c  | 183 +++++++++++++++++
 .../progs/percpu_alloc_cgrp_local_storage.c   | 105 ++++++++++
 .../selftests/bpf/progs/percpu_alloc_fail.c   | 164 +++++++++++++++
 .../selftests/bpf/test_bpftool_synctypes.py   |   9 +
 19 files changed, 853 insertions(+), 54 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/percpu_alloc.c
 create mode 100644 tools/testing/selftests/bpf/progs/percpu_alloc_array.c
 create mode 100644 tools/testing/selftests/bpf/progs/percpu_alloc_cgrp_local_storage.c
 create mode 100644 tools/testing/selftests/bpf/progs/percpu_alloc_fail.c

Comments

[e-mail] Sept. 6, 2023, 12:50 a.m. UTC | #1

Hello:

This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <[e-mail]>:

On Sun, 27 Aug 2023 08:27:29 -0700 you wrote:
> Patch set [1] implemented cgroup local storage BPF_MAP_TYPE_CGRP_STORAGE
> similar to sk/task/inode local storage and old BPF_MAP_TYPE_CGROUP_STORAGE
> map is marked as deprecated since old BPF_MAP_TYPE_CGROUP_STORAGE map can
> only work with current cgroup.
> 
> Similarly, the existing BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE map
> is a percpu version of BPF_MAP_TYPE_CGROUP_STORAGE and only works
> with current cgroup. But there is no replacement which can work
> with arbitrary cgroup.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3,01/13] bpf: Add support for non-fix-size percpu mem allocation
    https://git.kernel.org/bpf/bpf-next/c/baa9555b6c1c
  - [bpf-next,v3,02/13] bpf: Add BPF_KPTR_PERCPU as a field type
    https://git.kernel.org/bpf/bpf-next/c/b24d13fa6081
  - [bpf-next,v3,03/13] bpf: Add alloc/xchg/direct_access support for local percpu kptr
    https://git.kernel.org/bpf/bpf-next/c/b3122748321a
  - [bpf-next,v3,04/13] bpf: Add bpf_this_cpu_ptr/bpf_per_cpu_ptr support for allocated percpu obj
    https://git.kernel.org/bpf/bpf-next/c/119f4dfb73c5
  - [bpf-next,v3,05/13] selftests/bpf: Update error message in negative linked_list test
    https://git.kernel.org/bpf/bpf-next/c/dc5ed69ef3c4
  - [bpf-next,v3,06/13] libbpf: Add __percpu_kptr macro definition
    https://git.kernel.org/bpf/bpf-next/c/9ae302fe598b
  - [bpf-next,v3,07/13] selftests/bpf: Add bpf_percpu_obj_{new,drop}() macro in bpf_experimental.h
    https://git.kernel.org/bpf/bpf-next/c/7a03199abbc7
  - [bpf-next,v3,08/13] selftests/bpf: Add tests for array map with local percpu kptr
    https://git.kernel.org/bpf/bpf-next/c/ef570811b2e8
  - [bpf-next,v3,09/13] bpf: Mark OBJ_RELEASE argument as MEM_RCU when possible
    https://git.kernel.org/bpf/bpf-next/c/616334e5036b
  - [bpf-next,v3,10/13] selftests/bpf: Remove unnecessary direct read of local percpu kptr
    https://git.kernel.org/bpf/bpf-next/c/974da9f3ee66
  - [bpf-next,v3,11/13] selftests/bpf: Add tests for cgrp_local_storage with local percpu kptr
    https://git.kernel.org/bpf/bpf-next/c/38bbd586889f
  - [bpf-next,v3,12/13] selftests/bpf: Add some negative tests
    https://git.kernel.org/bpf/bpf-next/c/2bc5f8c5dbe4
  - [bpf-next,v3,13/13] bpf: Mark BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE deprecated
    https://git.kernel.org/bpf/bpf-next/c/fb94bcc2b286

You are awesome, thank you!