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?
