bpf: Account for BPF_FETCH in insn_has_def32()
insn_has_def32() returns false for 32-bit BPF_FETCH insns. This makes adjust_insn_aux_data() incorrectly set zext_dst, as can be seen in [1]. This happens because insn_no_def() does not know about the BPF_FETCH variants of BPF_STX. Fix in two steps. First, replace insn_no_def() with insn_def_regno(), which returns the register an insn defines. Normally insn_no_def() calls are followed by insn->dst_reg uses; replace those with the insn_def_regno() return value. Second, adjust the BPF_STX special case in is_reg64() to deal with queries made from opt_subreg_zext_lo32_rnd_hi32(), where the state information is no longer available. Add a comment, since the purpose of this special case is not clear at first glance. [1] https://lore.kernel.org/bpf/20210223150845.1857620-1-jackmanb@google.com/ Fixes: 5ffa2550 ("bpf: Add instructions for atomic_[cmp]xchg") Signed-off-by:Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Acked-by:
Martin KaFai Lau <kafai@fb.com> Acked-by:
Brendan Jackman <jackmanb@google.com> Link: https://lore.kernel.org/bpf/20210301154019.129110-1-iii@linux.ibm.com
parent
2b2aedab