cpu_nr is a 32 bit value and BPF_REG_0 is a 64 bit register, when ly loads the cpu_nr into BPF_REG_0 it does not zero the upper bits, but llgf does. Link: https://sashiko.dev/#/patchset/20260414142930.528751-1-max%40linux.ibm.com Fixes: 9012cf2491e3 ("s390/bpf: Inline smp_processor_id and current_task") Signed-off-by: Maxim Khmelevskii Reviewed-by: Ilya Leoshkevich --- arch/s390/net/bpf_jit_comp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 14eaaa5b2185..d62c5838c741 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -1783,8 +1783,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, insn->imm == BPF_FUNC_get_smp_processor_id) { const u32 *cpu_nr = &get_lowcore()->cpu_nr; - /* ly %b0, cpu_nr */ - EMIT6_DISP_LH(0xe3000000, 0x0058, BPF_REG_0, REG_0, REG_0, + /* llgf %b0, cpu_nr */ + EMIT6_DISP_LH(0xe3000000, 0x0016, BPF_REG_0, REG_0, REG_0, (unsigned long)cpu_nr); break; } -- 2.54.0