On 11/28, Yonghong Song wrote: > Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8b9 > ("bpf: Support new 32bit offset jmp instruction") added support for new > 32bit offset jmp instruction. Unfortunately, in function > bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset > (plus/minor a small delta) compares to 16-bit offset bound > [S16_MIN, S16_MAX], which caused the following verification failure: > $ ./test_progs-cpuv4 -t verif_scale_pyperf180 > ... > insn 10 cannot be patched due to 16-bit range > ... > libbpf: failed to load object 'pyperf180.bpf.o' > scale_test:FAIL:expect_success unexpected error: -12 (errno 12) > #405 verif_scale_pyperf180:FAIL > > Note that due to recent llvm18 development, the patch [2] (already applied > in bpf-next) needs to be applied to bpf tree for testing purpose. > > The fix is rather simple. For 32bit offset branch insn, the adjusted > offset compares to [S32_MIN, S32_MAX] and then verification succeeded. > > [1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@xxxxxxxxx > [2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@xxxxxxxxx > > Fixes: 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") > Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx> Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>