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Code Issues Releases Wiki Activity

bpf, docs: Clarify helper ID and pointer terms in instruction-set.rst 

Per IETF 119 meeting discussion and mailing list discussion at
https://mailarchive.ietf.org/arch/msg/bpf/2JwWQwFdOeMGv0VTbD0CKWwAOEA/
the following changes are made.

First, say call by "static ID" rather than call by "address"

Second, change "pointer" to "address"

Signed-off-by: Dave Thaler <dthaler1968@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20240419203617.6850-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Dave Thaler 2024-04-19 13:36:17 -07:00 committed by Alexei Starovoitov
parent 2ea0aa5358
commit db50040d09
1 changed files with 24 additions and 24 deletions
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48
Documentation/bpf/standardization/instruction-set.rst
View File

@ -443,27 +443,27 @@ otherwise identical operations, and indicates the base64 conformance
group unless otherwise specified.
The 'code' field encodes the operation as below:
======== ===== ======= =============================== ===================================================
code value src_reg description notes
======== ===== ======= =============================== ===================================================
JA 0x0 0x0 PC += offset {JA, K, JMP} only
JA 0x0 0x0 PC += imm {JA, K, JMP32} only
======== ===== ======= ================================= ===================================================
code value src_reg description notes
======== ===== ======= ================================= ===================================================
JA 0x0 0x0 PC += offset {JA, K, JMP} only
JA 0x0 0x0 PC += imm {JA, K, JMP32} only
JEQ 0x1 any PC += offset if dst == src
JGT 0x2 any PC += offset if dst > src unsigned
JGE 0x3 any PC += offset if dst >= src unsigned
JGT 0x2 any PC += offset if dst > src unsigned
JGE 0x3 any PC += offset if dst >= src unsigned
JSET 0x4 any PC += offset if dst & src
JNE 0x5 any PC += offset if dst != src
JSGT 0x6 any PC += offset if dst > src signed
JSGE 0x7 any PC += offset if dst >= src signed
CALL 0x8 0x0 call helper function by address {CALL, K, JMP} only, see `Helper functions`_
CALL 0x8 0x1 call PC += imm {CALL, K, JMP} only, see `Program-local functions`_
CALL 0x8 0x2 call helper function by BTF ID {CALL, K, JMP} only, see `Helper functions`_
EXIT 0x9 0x0 return {CALL, K, JMP} only
JLT 0xa any PC += offset if dst < src unsigned
JLE 0xb any PC += offset if dst <= src unsigned
JSLT 0xc any PC += offset if dst < src signed
JSLE 0xd any PC += offset if dst <= src signed
======== ===== ======= =============================== ===================================================
JSGT 0x6 any PC += offset if dst > src signed
JSGE 0x7 any PC += offset if dst >= src signed
CALL 0x8 0x0 call helper function by static ID {CALL, K, JMP} only, see `Helper functions`_
CALL 0x8 0x1 call PC += imm {CALL, K, JMP} only, see `Program-local functions`_
CALL 0x8 0x2 call helper function by BTF ID {CALL, K, JMP} only, see `Helper functions`_
EXIT 0x9 0x0 return {CALL, K, JMP} only
JLT 0xa any PC += offset if dst < src unsigned
JLE 0xb any PC += offset if dst <= src unsigned
JSLT 0xc any PC += offset if dst < src signed
JSLE 0xd any PC += offset if dst <= src signed
======== ===== ======= ================================= ===================================================
The BPF program needs to store the return value into register R0 before doing an
``EXIT``.
@ -498,9 +498,9 @@ Helper functions
Helper functions are a concept whereby BPF programs can call into a
set of function calls exposed by the underlying platform.
Historically, each helper function was identified by an address
Historically, each helper function was identified by a static ID
encoded in the 'imm' field. The available helper functions may differ
for each program type, but address values are unique across all program types.
for each program type, but static IDs 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
@ -667,11 +667,11 @@ src_reg pseudocode imm type dst type
======= ========================================= =========== ==============
0x0 dst = (next_imm << 32) | imm integer integer
0x1 dst = map_by_fd(imm) map fd map
0x2 dst = map_val(map_by_fd(imm)) + next_imm map fd data pointer
0x3 dst = var_addr(imm) variable id data pointer
0x4 dst = code_addr(imm) integer code pointer
0x2 dst = map_val(map_by_fd(imm)) + next_imm map fd data address
0x3 dst = var_addr(imm) variable id data address
0x4 dst = code_addr(imm) integer code address
0x5 dst = map_by_idx(imm) map index map
0x6 dst = map_val(map_by_idx(imm)) + next_imm map index data pointer
0x6 dst = map_val(map_by_idx(imm)) + next_imm map index data address
======= ========================================= =========== ==============
where