在 2023/4/7 18:49, Feng Zhou 写道:

在 2023/4/7 17:33, Jiri Olsa 写道:

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On Fri, Apr 07, 2023 at 04:46:06PM +0800, Feng zhou wrote:

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From: Feng Zhouzhoufeng.zf@bytedance.com

When access traced function arguments with type is u32*, bpf verifier failed. Because u32 have typedef, needs to skip modifier. Add btf_type_is_modifier in is_int_ptr. Add a selftest to check it.

Feng Zhou (2):    bpf/btf: Fix is_int_ptr()    selftests/bpf: Add test to access u32 ptr argument in tracing program

hi, it breaks several tests in test_progs suite:

#11/36   bpf_iter/link-iter:FAIL #11      bpf_iter:FAIL test_dummy_st_ops_attach:FAIL:dummy_st_ops_load unexpected error: -13 #63/1    dummy_st_ops/dummy_st_ops_attach:FAIL test_dummy_init_ret_value:FAIL:dummy_st_ops_load unexpected error: -13 #63/2    dummy_st_ops/dummy_init_ret_value:FAIL test_dummy_init_ptr_arg:FAIL:dummy_st_ops_load unexpected error: -13 #63/3    dummy_st_ops/dummy_init_ptr_arg:FAIL test_dummy_multiple_args:FAIL:dummy_st_ops_load unexpected error: -13 #63/4    dummy_st_ops/dummy_multiple_args:FAIL test_dummy_sleepable:FAIL:dummy_st_ops_load unexpected error: -13 #63/5    dummy_st_ops/dummy_sleepable:FAIL #63      dummy_st_ops:FAIL test_fentry_fexit:FAIL:fentry_skel_load unexpected error: -13 #69      fentry_fexit:FAIL test_fentry_test:FAIL:fentry_skel_load unexpected error: -13 #70      fentry_test:FAIL

jirka

I tried it, and it did cause the test to fail. Bpfverify reported an error, 'R1 invalid mem access'scalar', let me confirm the reason.

I used btf_type_skip_modifiers，but did not delete the previous "t = btf_type_by_id (btf, t- > type);" resulting in some testcases failing. I will send a v3 nextweek, thank you for your suggestion.

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Changelog: v1->v2: Addressed comments from Martin KaFai Lau

• Add a selftest.
• use btf_type_skip_modifiers.

Some details in here: https://lore.kernel.org/all/20221012125815.76120-1-zhouchengming@bytedance.c...

kernel/bpf/btf.c                                    |  5 ++---   net/bpf/test_run.c                                  |  8 +++++++-   .../testing/selftests/bpf/verifier/btf_ctx_access.c | 13 +++++++++++++   3 files changed, 22 insertions(+), 4 deletions(-)

-- 2.20.1