Add test cases for clear_stack_for_all_offs and dst_is_local_fp
handling of multi-offset and ARG_IMPRECISE stack pointers:
- st_imm_join_with_multi_off: BPF_ST through multi-offset dst should
join at_stack with none instead of overwriting both candidate slots.
- st_imm_join_with_imprecise_off: BPF_ST through offset-imprecise dst
should join at_stack with none instead of clearing all slots.
- st_imm_join_with_single_off: a canary checking that BPF_ST with a
known offset overwrites slot instead of joining.
- imprecise_dst_spill_join: BPF_STX through ARG_IMPRECISE dst should
be recognized as a local spill and join at_stack with the written
value.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260413-stacklive-fixes-v2-2-398e126e5cf3@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- simple propagation of read/write marks;
- joining read/write marks from conditional branches;
- avoid must_write marks in when same instruction accesses different
stack offsets on different execution paths;
- avoid must_write marks in case same instruction accesses stack
and non-stack pointers on different execution paths;
- read/write marks propagation to outer stack frame;
- independent read marks for different callchains ending with the same
function;
- bpf_calls_callback() dependent logic in
liveness.c:bpf_stack_slot_alive().
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250918-callchain-sensitive-liveness-v3-12-c3cd27bacc60@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
