v1: https://lore.kernel.org/bpf/20250812141217.144551-1-iii@xxxxxxxxxxxxx/ v1 -> v2: Write back tail call counter only for BPF_PSEUDO_CALL Hi, This series fixes the tailcall_bpf2bpf_hierarchy test failures on s390. It takes a simpler approach than x86_64 and aarch64: instead of introducing a pointer to the tail call counter, it copies the updated value back from the callee's frame to the caller's frame. This needs to be done in two locations: after BPF_PSEUDO_CALL and after BPF_TRAMP_F_CALL_ORIG. Patch 1 is a cleanup, patches 2 and 3 are the actual fixes, patch 4 improves the hierarchy tests in order to catch issues with accidentally clobbering the counter. Best regards, Ilya Ilya Leoshkevich (4): s390/bpf: Do not write tail call counter into helper and kfunc frames s390/bpf: Write back tail call counter for BPF_PSEUDO_CALL s390/bpf: Write back tail call counter for BPF_TRAMP_F_CALL_ORIG selftests/bpf: Clobber a lot of registers in tailcall_bpf2bpf_hierarchy tests arch/s390/net/bpf_jit_comp.c | 42 ++++++++++++++----- .../selftests/bpf/progs/bpf_test_utils.h | 18 ++++++++ .../bpf/progs/tailcall_bpf2bpf_hierarchy1.c | 3 ++ .../bpf/progs/tailcall_bpf2bpf_hierarchy2.c | 3 ++ .../bpf/progs/tailcall_bpf2bpf_hierarchy3.c | 3 ++ .../progs/tailcall_bpf2bpf_hierarchy_fentry.c | 3 ++ 6 files changed, 61 insertions(+), 11 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/bpf_test_utils.h -- 2.50.1
