On 2025/10/22 16:01, Menglong Dong wrote: > Sometimes, we need to hook both the entry and exit of a function with > TRACING. Therefore, we need define a FENTRY and a FEXIT for the target > function, which is not convenient. > > Therefore, we add a tracing session support for TRACING. Generally > speaking, it's similar to kprobe session, which can hook both the entry > and exit of a function with a single BPF program. Meanwhile, it can also > control the execution of the fexit with the return value of the fentry. > Session cookie is also supported with the kfunc bpf_fsession_cookie(). > > The kfunc bpf_tracing_is_exit() and bpf_fsession_cookie() are both inlined > in the verifier.
Hmm......the gmail broken after it sent the 7th patch. So I sent the remained 3 patches again. However, they are not recognized together as a series. So awkward :/ Should I resend it? Thanks! Menglong Dong > > We allow the usage of bpf_get_func_ret() to get the return value in the > fentry of the tracing session, as it will always get "0", which is safe > enough and is OK. > > The while fsession stuff is arch related, so the -EOPNOTSUPP will be > returned if it is not supported yet by the arch. In this series, we only > support x86_64. And later, other arch will be implemented. > > Changes since v1: > * session cookie support. > In this version, session cookie is implemented, and the kfunc > bpf_fsession_cookie() is added. > > * restructure the layout of the stack. > In this version, the session stuff that stored in the stack is changed, > and we locate them after the return value to not break > bpf_get_func_ip(). > > * testcase enhancement. > Some nits in the testcase that suggested by Jiri is fixed. Meanwhile, > the testcase for get_func_ip and session cookie is added too. > > Menglong Dong (10): > bpf: add tracing session support > bpf: add kfunc bpf_tracing_is_exit for TRACE_SESSION > bpf: add kfunc bpf_fsession_cookie for TRACING SESSION > bpf,x86: add ret_off to invoke_bpf() > bpf,x86: add tracing session supporting for x86_64 > libbpf: add support for tracing session > selftests/bpf: test get_func_ip for fsession > selftests/bpf: add testcases for tracing session > selftests/bpf: add session cookie testcase for fsession > selftests/bpf: add testcase for mixing fsession, fentry and fexit > > arch/arm64/net/bpf_jit_comp.c | 3 + > arch/loongarch/net/bpf_jit.c | 3 + > arch/powerpc/net/bpf_jit_comp.c | 3 + > arch/riscv/net/bpf_jit_comp64.c | 3 + > arch/s390/net/bpf_jit_comp.c | 3 + > arch/x86/net/bpf_jit_comp.c | 214 ++++++++++++++++-- > include/linux/bpf.h | 2 + > include/uapi/linux/bpf.h | 1 + > kernel/bpf/btf.c | 2 + > kernel/bpf/syscall.c | 2 + > kernel/bpf/trampoline.c | 5 +- > kernel/bpf/verifier.c | 45 +++- > kernel/trace/bpf_trace.c | 59 ++++- > net/bpf/test_run.c | 1 + > net/core/bpf_sk_storage.c | 1 + > tools/bpf/bpftool/common.c | 1 + > tools/include/uapi/linux/bpf.h | 1 + > tools/lib/bpf/bpf.c | 2 + > tools/lib/bpf/libbpf.c | 3 + > .../selftests/bpf/prog_tests/fsession_test.c | 161 +++++++++++++ > .../bpf/prog_tests/get_func_ip_test.c | 2 + > .../bpf/prog_tests/tracing_failure.c | 2 +- > .../selftests/bpf/progs/fsession_cookie.c | 49 ++++ > .../selftests/bpf/progs/fsession_mixed.c | 45 ++++ > .../selftests/bpf/progs/fsession_test.c | 175 ++++++++++++++ > .../selftests/bpf/progs/get_func_ip_test.c | 14 ++ > 26 files changed, 776 insertions(+), 26 deletions(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/fsession_test.c > create mode 100644 tools/testing/selftests/bpf/progs/fsession_cookie.c > create mode 100644 tools/testing/selftests/bpf/progs/fsession_mixed.c > create mode 100644 tools/testing/selftests/bpf/progs/fsession_test.c > >
