[bpf-next,v4,0/4] introduce dummy BPF STRUCT_OPS

Message

Hou Tao Oct. 25, 2021, 6:40 a.m. UTC

Hi,

Currently the test of BPF STRUCT_OPS depends on the specific bpf
implementation (e.g, tcp_congestion_ops), but it can not cover all
basic functionalities (e.g, return value handling), so introduce
a dummy BPF STRUCT_OPS for test purpose.

Instead of loading a userspace-implemeted bpf_dummy_ops map into
kernel and calling the specific function by writing to sysfs provided
by bpf_testmode.ko, only loading bpf_dummy_ops related prog into
kernel and calling these prog by bpf_prog_test_run(). The latter
is more flexible and has no dependency on extra kernel module.

Now the return value handling is supported by test_1(...) ops,
and passing multiple arguments is supported by test_2(...) ops.
If more is needed, test_x(...) ops can be added afterwards.

Comments are always welcome.
Regards,
Hou

Change Log:
v4:
 * add Acked-by tags in patch 1~4
 * patch 2: remove unncessary comments and update commit message
            accordingly
 * patch 4: remove unnecessary nr checking in dummy_ops_init_args()

v3: https://www.spinics.net/lists/bpf/msg48303.html
 * rebase on bpf-next
 * address comments for Martin, mainly include: merge patch 3 &
   patch 4 in v2, fix names of btf ctx access check helpers,
   handle CONFIG_NET, fix leak in dummy_ops_init_args(), and
   simplify bpf_dummy_init()
 * patch 4: use a loop to check args in test_dummy_multiple_args()

v2: https://www.spinics.net/lists/bpf/msg47948.html
 * rebase on bpf-next
 * add test_2(...) ops to test the passing of multiple arguments
 * a new patch (patch #2) is added to factor out ctx access helpers
 * address comments from Martin & Andrii

v1: https://www.spinics.net/lists/bpf/msg46787.html

RFC: https://www.spinics.net/lists/bpf/msg46117.html


Hou Tao (4):
  bpf: factor out a helper to prepare trampoline for struct_ops prog
  bpf: factor out helpers for ctx access checking
  bpf: add dummy BPF STRUCT_OPS for test purpose
  selftests/bpf: add test cases for struct_ops prog

 include/linux/bpf.h                           |  43 ++++
 kernel/bpf/bpf_struct_ops.c                   |  32 ++-
 kernel/bpf/bpf_struct_ops_types.h             |   3 +
 kernel/trace/bpf_trace.c                      |  16 +-
 net/bpf/Makefile                              |   3 +
 net/bpf/bpf_dummy_struct_ops.c                | 200 ++++++++++++++++++
 net/ipv4/bpf_tcp_ca.c                         |   9 +-
 .../selftests/bpf/prog_tests/dummy_st_ops.c   | 115 ++++++++++
 .../selftests/bpf/progs/dummy_st_ops.c        |  50 +++++
 9 files changed, 439 insertions(+), 32 deletions(-)
 create mode 100644 net/bpf/bpf_dummy_struct_ops.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c
 create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops.c

Comments

Hou Tao Oct. 29, 2021, 10:55 a.m. UTC | #1

Hi Alexei,

Could you please consider the patch set for 5.16 ? The whole patch set has
already been Acked by Martin.

Thanks.

On 10/25/2021 2:40 PM, Hou Tao wrote:
> Hi,
>
> Currently the test of BPF STRUCT_OPS depends on the specific bpf
> implementation (e.g, tcp_congestion_ops), but it can not cover all
> basic functionalities (e.g, return value handling), so introduce
> a dummy BPF STRUCT_OPS for test purpose.
>
> Instead of loading a userspace-implemeted bpf_dummy_ops map into
> kernel and calling the specific function by writing to sysfs provided
> by bpf_testmode.ko, only loading bpf_dummy_ops related prog into
> kernel and calling these prog by bpf_prog_test_run(). The latter
> is more flexible and has no dependency on extra kernel module.
>
> Now the return value handling is supported by test_1(...) ops,
> and passing multiple arguments is supported by test_2(...) ops.
> If more is needed, test_x(...) ops can be added afterwards.
>
> Comments are always welcome.
> Regards,
> Hou
>
> Change Log:
> v4:
>  * add Acked-by tags in patch 1~4
>  * patch 2: remove unncessary comments and update commit message
>             accordingly
>  * patch 4: remove unnecessary nr checking in dummy_ops_init_args()
>
> v3: https://www.spinics.net/lists/bpf/msg48303.html
>  * rebase on bpf-next
>  * address comments for Martin, mainly include: merge patch 3 &
>    patch 4 in v2, fix names of btf ctx access check helpers,
>    handle CONFIG_NET, fix leak in dummy_ops_init_args(), and
>    simplify bpf_dummy_init()
>  * patch 4: use a loop to check args in test_dummy_multiple_args()
>
> v2: https://www.spinics.net/lists/bpf/msg47948.html
>  * rebase on bpf-next
>  * add test_2(...) ops to test the passing of multiple arguments
>  * a new patch (patch #2) is added to factor out ctx access helpers
>  * address comments from Martin & Andrii
>
> v1: https://www.spinics.net/lists/bpf/msg46787.html
>
> RFC: https://www.spinics.net/lists/bpf/msg46117.html
>
>
> Hou Tao (4):
>   bpf: factor out a helper to prepare trampoline for struct_ops prog
>   bpf: factor out helpers for ctx access checking
>   bpf: add dummy BPF STRUCT_OPS for test purpose
>   selftests/bpf: add test cases for struct_ops prog
>
>  include/linux/bpf.h                           |  43 ++++
>  kernel/bpf/bpf_struct_ops.c                   |  32 ++-
>  kernel/bpf/bpf_struct_ops_types.h             |   3 +
>  kernel/trace/bpf_trace.c                      |  16 +-
>  net/bpf/Makefile                              |   3 +
>  net/bpf/bpf_dummy_struct_ops.c                | 200 ++++++++++++++++++
>  net/ipv4/bpf_tcp_ca.c                         |   9 +-
>  .../selftests/bpf/prog_tests/dummy_st_ops.c   | 115 ++++++++++
>  .../selftests/bpf/progs/dummy_st_ops.c        |  50 +++++
>  9 files changed, 439 insertions(+), 32 deletions(-)
>  create mode 100644 net/bpf/bpf_dummy_struct_ops.c
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c
>  create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops.c
>