>> 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. > > I will use that syntax in binutils for now. https://sourceware.org/pipermail/binutils/2023-July/128543.html Now we will make GCC to use that instruction whenever needed, but only with -mcpu=v4 or later: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110781 >> [1] https://reviews.llvm.org/D144829 >> >>> >>> > Thanks, >>> > Eduard >>> > >>> > [1] https://www.kernel.org/doc/html/latest/bpf/instruction-set.html#jump-instructions
