On Sun, 2023-07-23 at 21:14 +0200, Jose E. Marchesi wrote: > > On Fri, 2023-07-21 at 18:19 +0200, Jose E. Marchesi wrote: > > > Hi Yonghong. > > > > > > This is from the v4 instructions proposal: > > > > > > ======== ===== ========================= ============ > > > code value description notes > > > ======== ===== ========================= ============ > > > BPF_JA 0x00 PC += imm BPF_JMP32 only > > > > > > Is this instruction using source 1 instead of 0? Otherwise, it would > > > have exactly the same encoding than the V3< JA instruction. Is that > > > what is intended? > > > > > > TIA. > > > > > > > Hi Jose, > > > > I think that assumption is that `BPF_JMP32 | BPF_JA` is currently free: > > - documentation [1] implies that only `BPF_JMP` should be used for `BPF_JA` > > (see "notes" column for the first line) > > - BPF verifier rejects `BPF_JMP32 | BPF_JA` > > - clang always generates `BPF_JMP | BPF_JA` > > Makes sense, thanks for the info. > > Do you know the precise pseudo-c assembly syntax to use for this > instruction? In [1] Yonghong uses the following form: gotol +0xcd9b But it seems to be not specified in the documentation for the patch-set v3. [1] https://reviews.llvm.org/D144829 > > > Thanks, > > Eduard > > > > [1] https://www.kernel.org/doc/html/latest/bpf/instruction-set.html#jump-instructions
