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authorJiong Wang <jiong.wang@netronome.com>2019-01-26 12:25:59 -0500
committerAlexei Starovoitov <ast@kernel.org>2019-01-26 13:33:01 -0800
commitd405c7407a5468d4fc11724d76063e0647d80106 (patch)
treeb3bbcb8825be07aed9a355ca289d08e5611cb307 /Documentation
parentdbbd79ae166fbd37ceaef77a96b5a99cce0022c3 (diff)
downloadlinux-d405c7407a5468d4fc11724d76063e0647d80106.tar.bz2
bpf: allocate 0x06 to new eBPF instruction class JMP32
The new eBPF instruction class JMP32 uses the reserved class number 0x6. Kernel BPF ISA documentation updated accordingly. Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/networking/filter.txt15
1 files changed, 8 insertions, 7 deletions
diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
index 2196b824e96c..01603bc2eff1 100644
--- a/Documentation/networking/filter.txt
+++ b/Documentation/networking/filter.txt
@@ -865,7 +865,7 @@ Three LSB bits store instruction class which is one of:
BPF_STX 0x03 BPF_STX 0x03
BPF_ALU 0x04 BPF_ALU 0x04
BPF_JMP 0x05 BPF_JMP 0x05
- BPF_RET 0x06 [ class 6 unused, for future if needed ]
+ BPF_RET 0x06 BPF_JMP32 0x06
BPF_MISC 0x07 BPF_ALU64 0x07
When BPF_CLASS(code) == BPF_ALU or BPF_JMP, 4th bit encodes source operand ...
@@ -902,9 +902,9 @@ If BPF_CLASS(code) == BPF_ALU or BPF_ALU64 [ in eBPF ], BPF_OP(code) is one of:
BPF_ARSH 0xc0 /* eBPF only: sign extending shift right */
BPF_END 0xd0 /* eBPF only: endianness conversion */
-If BPF_CLASS(code) == BPF_JMP, BPF_OP(code) is one of:
+If BPF_CLASS(code) == BPF_JMP or BPF_JMP32 [ in eBPF ], BPF_OP(code) is one of:
- BPF_JA 0x00
+ BPF_JA 0x00 /* BPF_JMP only */
BPF_JEQ 0x10
BPF_JGT 0x20
BPF_JGE 0x30
@@ -912,8 +912,8 @@ If BPF_CLASS(code) == BPF_JMP, BPF_OP(code) is one of:
BPF_JNE 0x50 /* eBPF only: jump != */
BPF_JSGT 0x60 /* eBPF only: signed '>' */
BPF_JSGE 0x70 /* eBPF only: signed '>=' */
- BPF_CALL 0x80 /* eBPF only: function call */
- BPF_EXIT 0x90 /* eBPF only: function return */
+ BPF_CALL 0x80 /* eBPF BPF_JMP only: function call */
+ BPF_EXIT 0x90 /* eBPF BPF_JMP only: function return */
BPF_JLT 0xa0 /* eBPF only: unsigned '<' */
BPF_JLE 0xb0 /* eBPF only: unsigned '<=' */
BPF_JSLT 0xc0 /* eBPF only: signed '<' */
@@ -936,8 +936,9 @@ Classic BPF wastes the whole BPF_RET class to represent a single 'ret'
operation. Classic BPF_RET | BPF_K means copy imm32 into return register
and perform function exit. eBPF is modeled to match CPU, so BPF_JMP | BPF_EXIT
in eBPF means function exit only. The eBPF program needs to store return
-value into register R0 before doing a BPF_EXIT. Class 6 in eBPF is currently
-unused and reserved for future use.
+value into register R0 before doing a BPF_EXIT. Class 6 in eBPF is used as
+BPF_JMP32 to mean exactly the same operations as BPF_JMP, but with 32-bit wide
+operands for the comparisons instead.
For load and store instructions the 8-bit 'code' field is divided as: