On Sat, Mar 25, 2023 at 10:23:14AM +0000, Dave Thaler wrote: > From: Dave Thaler <dthaler@xxxxxxxxxxxxx> > > Add extended call instructions. Uses the term "program-local" for > call by offset. And there are instructions for calling helper functions > by "address" (the old way of using integer values), and for calling > helper functions by BTF ID (for kfuncs). > > --- > V1 -> V2: addressed comments from David Vernet > > V2 -> V3: make descriptions in table consistent with updated names > > V3 -> V4: addressed comments from Alexei > > Signed-off-by: Dave Thaler <dthaler@xxxxxxxxxxxxx> Looks great, thanks for driving this to consensus. Just left one nit below, but here's my stamp regardless: Acked-by: David Vernet <void@xxxxxxxxxxxxx> > --- > Documentation/bpf/instruction-set.rst | 59 +++++++++++++++++---------- > 1 file changed, 37 insertions(+), 22 deletions(-) > > diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst > index 5e43e14abe8..ed8f35becb2 100644 > --- a/Documentation/bpf/instruction-set.rst > +++ b/Documentation/bpf/instruction-set.rst > @@ -242,35 +242,50 @@ Jump instructions > otherwise identical operations. > The 'code' field encodes the operation as below: > > -======== ===== ========================= ============ > -code value description notes > -======== ===== ========================= ============ > -BPF_JA 0x00 PC += off BPF_JMP only > -BPF_JEQ 0x10 PC += off if dst == src > -BPF_JGT 0x20 PC += off if dst > src unsigned > -BPF_JGE 0x30 PC += off if dst >= src unsigned > -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 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 > -BPF_JSLT 0xc0 PC += off if dst < src signed > -BPF_JSLE 0xd0 PC += off if dst <= src signed > -======== ===== ========================= ============ > +======== ===== === =========================================== ========================================= > +code value src description notes > +======== ===== === =========================================== ========================================= > +BPF_JA 0x0 0x0 PC += offset BPF_JMP only > +BPF_JEQ 0x1 any PC += offset if dst == src > +BPF_JGT 0x2 any PC += offset if dst > src unsigned > +BPF_JGE 0x3 any PC += offset if dst >= src unsigned > +BPF_JSET 0x4 any PC += offset if dst & src > +BPF_JNE 0x5 any PC += offset if dst != src > +BPF_JSGT 0x6 any PC += offset if dst > src signed > +BPF_JSGE 0x7 any PC += offset if dst >= src signed > +BPF_CALL 0x8 0x0 call helper function by address see `Helper functions`_ nit: Seems like the alignment got messed up here? > +BPF_CALL 0x8 0x1 call PC += offset see `Program-local functions`_ > +BPF_CALL 0x8 0x2 call helper function by BTF ID see `Helper functions`_ > +BPF_EXIT 0x9 0x0 return BPF_JMP only > +BPF_JLT 0xa any PC += offset if dst < src unsigned > +BPF_JLE 0xb any PC += offset if dst <= src unsigned > +BPF_JSLT 0xc any PC += offset if dst < src signed > +BPF_JSLE 0xd any PC += offset if dst <= src signed > +======== ===== === =========================================== ========================================= > > The eBPF program needs to store the return value into register R0 before doing a > -BPF_EXIT. > +``BPF_EXIT``. > > Helper functions > ~~~~~~~~~~~~~~~~ > > Helper functions are a concept whereby BPF programs can call into a > -set of function calls exposed by the runtime. Each helper > -function is identified by an integer used in a ``BPF_CALL`` instruction. > -The available helper functions may differ for each program type. > +set of function calls exposed by the underlying platform. > + > +Historically, each helper function was identified by an address > +encoded in the imm field. The available helper functions may differ > +for each program type, but address values are unique across all program types. > + > +Platforms that support the BPF Type Format (BTF) support identifying > +a helper function by a BTF ID encoded in the imm field, where the BTF ID > +identifies the helper name and type. > + > +Program-local functions > +~~~~~~~~~~~~~~~~~~~~~~~ > +Program-local functions are functions exposed by the same BPF program as the > +caller, and are referenced by offset from the call instruction, similar to > +``BPF_JA``. A ``BPF_EXIT`` within the program-local function will return to > +the caller. > > Load and store instructions > =========================== > -- > 2.33.4 > > -- > Bpf mailing list > Bpf@xxxxxxxx > https://www.ietf.org/mailman/listinfo/bpf
