This series enables fentry on x86 BPF programs reached via tail calls and adds a focused selftest for the expected behavior.
Patch 1 fixes the x86 mirrored text-poke lookup so the tail-call landing slot is patched on both IBT and non-IBT JITs. Patch 2 adds a selftest that checks both direct entry and tail-called entry for a tailcall callee with fentry attached. Takeru Hayasaka (2): bpf, x86: patch tail-call fentry slot on non-IBT JITs selftests/bpf: cover fentry on tailcalled programs arch/x86/net/bpf_jit_comp.c | 47 +++++++- .../selftests/bpf/prog_tests/tailcalls.c | 110 ++++++++++++++++++ .../bpf/progs/tailcall_fentry_probe.c | 16 +++ .../bpf/progs/tailcall_fentry_target.c | 27 +++++ 4 files changed, 197 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/tailcall_fentry_probe.c create mode 100644 tools/testing/selftests/bpf/progs/tailcall_fentry_target.c -- 2.43.0
