> -----Original Message----- > From: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> > Sent: Wednesday, November 9, 2022 1:51 AM > To: dthaler1968@xxxxxxxxxxxxxx > Cc: bpf <bpf@xxxxxxxxxxxxxxx>; Dave Thaler <dthaler@xxxxxxxxxxxxx> > Subject: Re: [PATCH 4/4] bpf, docs: Explain helper functions > > On Thu, Oct 27, 2022 at 7:46 AM <dthaler1968@xxxxxxxxxxxxxx> wrote: > > > > From: Dave Thaler <dthaler@xxxxxxxxxxxxx> > > > > Explain helper functions > > > > Signed-off-by: Dave Thaler <dthaler@xxxxxxxxxxxxx> > > --- > > Documentation/bpf/instruction-set.rst | 18 +++++++++++++++++- > > 1 file changed, 17 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/bpf/instruction-set.rst > > b/Documentation/bpf/instruction-set.rst > > index aa1b37cb5..40c3293d6 100644 > > --- a/Documentation/bpf/instruction-set.rst > > +++ b/Documentation/bpf/instruction-set.rst > > @@ -242,7 +242,7 @@ BPF_JSET 0x40 PC += off if dst & src > > BPF_JNE 0x50 PC += off if dst != src > > BPF_JSGT 0x60 PC += off if dst > src signed > > BPF_JSGE 0x70 PC += off if dst >= src signed > > -BPF_CALL 0x80 function call > > +BPF_CALL 0x80 function call see `Helper functions`_ > > BPF_EXIT 0x90 function / program return BPF_JMP only > > BPF_JLT 0xa0 PC += off if dst < src unsigned > > BPF_JLE 0xb0 PC += off if dst <= src unsigned > > @@ -253,6 +253,22 @@ BPF_JSLE 0xd0 PC += off if dst <= src signed > > The eBPF program needs to store the return value into register R0 > > before doing a BPF_EXIT. > > > > +Helper functions > > +~~~~~~~~~~~~~~~~ > > +Helper functions are a concept whereby BPF programs can call into a > > +set of function calls exposed by the eBPF runtime. Each helper > > eBPF right next to BPF looks odd. Let's stick to BPF everywhere? Since the brand is eBPF, could we stick to eBPF everywhere except the actual defines (BPF_CALL, etc. have to be literal)? Dave
