| Message ID | 20230311220912.5546-1-dthaler1968@googlemail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,v2] bpf, docs: Add extended call instructions | expand |
Dave Thaler wrote: > From: Dave Thaler <dthaler@microsoft.com> > > Add extended call instructions. Since BPF can be used in userland > or SmartNICs, this uses the more generic "Platform-specific helper functions" > term as suggested by David Vernet, rather than the kernel specific "kfuncs". > > --- > V1 -> V2: addressed comments from David Vernet > > Signed-off-by: Dave Thaler <dthaler@microsoft.com> > --- > Documentation/bpf/instruction-set.rst | 63 +++++++++++++++++---------- > Documentation/bpf/linux-notes.rst | 4 ++ > 2 files changed, 44 insertions(+), 23 deletions(-) > > diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst > index 5e43e14abe8..dc348544542 100644 > --- a/Documentation/bpf/instruction-set.rst > +++ b/Documentation/bpf/instruction-set.rst > @@ -242,35 +242,52 @@ 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 imm see `Platform-agnostic helper functions`_ > +BPF_CALL 0x8 0x1 call PC += offset see `BPF-local functions`_ > +BPF_CALL 0x8 0x2 call runtime function imm see `Platform-specific 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. > > -Helper functions > -~~~~~~~~~~~~~~~~ > +Platform-agnostic helper functions > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > -Helper functions are a concept whereby BPF programs can call into a > -set of function calls exposed by the runtime. Each helper > +Platform-agnostic 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. > +The available platform-agnostic helper functions may differ for each program > +type, but integer values are unique across all program types. > + > +Platform-specific helper functions > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +Platform-specific helper functions are helper functions that are unique to > +a particular platform. They use a separate integer numbering space from > +platform-agnostic helper functions, but otherwise the same considerations How does the separate integer numbering space work in Linux? Here I guess we have platform agnostic and Linux specific helpers all mingled together correct? > +apply. Platforms are not required to implement any platform-specific > +functions. > + > +BPF-local functions > +~~~~~~~~~~~~~~ > +BPF-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 BPF-local function will return to the caller. > > Load and store instructions > =========================== > diff --git a/Documentation/bpf/linux-notes.rst b/Documentation/bpf/linux-notes.rst > index f43b9c797bc..bdc41293e8a 100644 > --- a/Documentation/bpf/linux-notes.rst > +++ b/Documentation/bpf/linux-notes.rst > @@ -20,6 +20,10 @@ integer would be read from a specified register, is not currently supported > by the verifier. Any programs with this instruction will fail to load > until such support is added. > > +For historical reasons, Linux has a number of Linux-specific helper functions > +that are encoded as platform-agnostic helper functions rather than > + platform-specific helper functions ("kfuncs"). Is this the comment to address above integer numbering space on Linux being inconsistent with above docs? > + > Legacy BPF Packet access instructions > ===================================== > > -- > 2.33.4 >
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst index 5e43e14abe8..dc348544542 100644 --- a/Documentation/bpf/instruction-set.rst +++ b/Documentation/bpf/instruction-set.rst @@ -242,35 +242,52 @@ 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 imm see `Platform-agnostic helper functions`_ +BPF_CALL 0x8 0x1 call PC += offset see `BPF-local functions`_ +BPF_CALL 0x8 0x2 call runtime function imm see `Platform-specific 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. -Helper functions -~~~~~~~~~~~~~~~~ +Platform-agnostic helper functions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Helper functions are a concept whereby BPF programs can call into a -set of function calls exposed by the runtime. Each helper +Platform-agnostic 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. +The available platform-agnostic helper functions may differ for each program +type, but integer values are unique across all program types. + +Platform-specific helper functions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Platform-specific helper functions are helper functions that are unique to +a particular platform. They use a separate integer numbering space from +platform-agnostic helper functions, but otherwise the same considerations +apply. Platforms are not required to implement any platform-specific +functions. + +BPF-local functions +~~~~~~~~~~~~~~ +BPF-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 BPF-local function will return to the caller. Load and store instructions =========================== diff --git a/Documentation/bpf/linux-notes.rst b/Documentation/bpf/linux-notes.rst index f43b9c797bc..bdc41293e8a 100644 --- a/Documentation/bpf/linux-notes.rst +++ b/Documentation/bpf/linux-notes.rst @@ -20,6 +20,10 @@ integer would be read from a specified register, is not currently supported by the verifier. Any programs with this instruction will fail to load until such support is added. +For historical reasons, Linux has a number of Linux-specific helper functions +that are encoded as platform-agnostic helper functions rather than + platform-specific helper functions ("kfuncs"). + Legacy BPF Packet access instructions =====================================