9.7.4 Opcodes

In the instruction descriptions below the following field descriptors are used:

%d
Destination general-purpose register whose role is to be destination of an operation.
%s
Source general-purpose register whose role is to be the source of an operation.
disp16
16-bit signed PC-relative offset, measured in number of 64-bit words, minus one.
disp32
32-bit signed PC-relative offset, measured in number of 64-bit words, minus one.
offset16
Signed 16-bit immediate.
imm32
Signed 32-bit immediate.
imm64
Signed 64-bit immediate.
9.7.4.1 Arithmetic instructions

The destination register in these instructions act like an accumulator.

add %d, (%s|imm32)
64-bit arithmetic addition.
sub %d, (%s|imm32)
64-bit arithmetic subtraction.
mul %d, (%s|imm32)
64-bit arithmetic multiplication.
div %d, (%s|imm32)
64-bit arithmetic integer division.
mod %d, (%s|imm32)
64-bit integer remainder.
and %d, (%s|imm32)
64-bit bit-wise “and” operation.
or %d, (%s|imm32)
64-bit bit-wise “or” operation.
xor %d, (%s|imm32)
64-bit bit-wise exclusive-or operation.
lsh %d, (%s|imm32)
64-bit left shift, by %s or imm32 bits.
rsh %d, (%s|imm32)
64-bit right logical shift, by %s or imm32 bits.
arsh %d, (%s|imm32)
64-bit right arithmetic shift, by %s or imm32 bits.
neg %d
64-bit arithmetic negation.
mov %d, (%s|imm32)
Move the 64-bit value of %s in %d , or load imm32 in %d .
9.7.4.2 32-bit arithmetic instructions

The destination register in these instructions act as an accumulator.

add32 %d, (%s|imm32)
32-bit arithmetic addition.
sub32 %d, (%s|imm32)
32-bit arithmetic subtraction.
mul32 %d, (%s|imm32)
32-bit arithmetic multiplication.
div32 %d, (%s|imm32)
32-bit arithmetic integer division.
mod32 %d, (%s|imm32)
32-bit integer remainder.
and32 %d, (%s|imm32)
32-bit bit-wise “and” operation.
or32 %d, (%s|imm32)
32-bit bit-wise “or” operation.
xor32 %d, (%s|imm32)
32-bit bit-wise exclusive-or operation.
lsh32 %d, (%s|imm32)
32-bit left shift, by %s or imm32 bits.
rsh32 %d, (%s|imm32)
32-bit right logical shift, by %s or imm32 bits.
arsh32 %d, (%s|imm32)
32-bit right arithmetic shift, by %s or imm32 bits.
neg32 %d
32-bit arithmetic negation.
mov32 %d, (%s|imm32)
Move the 32-bit value of %s in %d , or load imm32 in %d .
9.7.4.3 Endianness conversion instructions
endle %d, (8|16|32)
Convert the 8-bit, 16-bit or 32-bit value in %d to little-endian.
endbe %d, (8|16|32)
Convert the 8-bit, 16-bit or 32-bit value in %d to big-endian.
9.7.4.4 64-bit load and pseudo maps
lddw %d, imm64
Load the given signed 64-bit immediate, or pseudo map descriptor, to the destination register %d .
lddw %d, %map_fd(N)
Load the address of the given pseudo map fd N to the destination register %d .
9.7.4.5 Load instructions for socket filters

The following instructions are intended to be used in socket filters, and are therefore not general-purpose: they make assumptions on the contents of several registers. See the file Documentation/networking/filter.txt in the Linux kernel source tree for more information.

Absolute loads:

ldabsdw imm32
Absolute 64-bit load.
ldabsw imm32
Absolute 32-bit load.
ldabsh imm32
Absolute 16-bit load.
ldabsb imm32
Absolute 8-bit load.

Indirect loads:

ldinddw %s, imm32
Indirect 64-bit load.
ldindw %s, imm32
Indirect 32-bit load.
ldindh %s, imm32
Indirect 16-bit load.
ldindb %s, imm32
Indirect 8-bit load.
9.7.4.6 Generic load/store instructions

General-purpose load and store instructions are provided for several word sizes.

Load to register instructions:

ldxdw %d, [%s+offset16]
Generic 64-bit load.
ldxw %d, [%s+offset16]
Generic 32-bit load.
ldxh %d, [%s+offset16]
Generic 16-bit load.
ldxb %d, [%s+offset16]
Generic 8-bit load.

Store from register instructions:

stxdw [%d+offset16], %s
Generic 64-bit store.
stxw [%d+offset16], %s
Generic 32-bit store.
stxh [%d+offset16], %s
Generic 16-bit store.
stxb [%d+offset16], %s
Generic 8-bit store.

Store from immediates instructions:

stddw [%d+offset16], imm32
Store immediate as 64-bit.
stdw [%d+offset16], imm32
Store immediate as 32-bit.
stdh [%d+offset16], imm32
Store immediate as 16-bit.
stdb [%d+offset16], imm32
Store immediate as 8-bit.
9.7.4.7 Jump instructions

eBPF provides the following compare-and-jump instructions, which compare the values of the two given registers, or the values of a register and an immediate, and perform a branch in case the comparison holds true.

ja %d,(%s|imm32),disp16
Jump-always.
jeq %d,(%s|imm32),disp16
Jump if equal.
jgt %d,(%s|imm32),disp16
Jump if greater.
jge %d,(%s|imm32),disp16
Jump if greater or equal.
jlt %d,(%s|imm32),disp16
Jump if lesser.
jle %d,(%s|imm32),disp16
Jump if lesser or equal.
jset %d,(%s|imm32),disp16
Jump if signed equal.
jne %d,(%s|imm32),disp16
Jump if not equal.
jsgt %d,(%s|imm32),disp16
Jump if signed greater.
jsge %d,(%s|imm32),disp16
Jump if signed greater or equal.
jslt %d,(%s|imm32),disp16
Jump if signed lesser.
jsle %d,(%s|imm32),disp16
Jump if signed lesser or equal.

A call instruction is provided in order to perform calls to other eBPF functions, or to external kernel helpers:

call (disp32|imm32)
Jump and link to the offset disp32 , or to the kernel helper function identified by imm32 .

Finally:

exit
Terminate the eBPF program.
9.7.4.8 Atomic instructions

Atomic exchange-and-add instructions are provided in two flavors: one for swapping 64-bit quantities and another for 32-bit quantities.

xadddw [%d+offset16],%s
Exchange-and-add a 64-bit value at the specified location.
xaddw [%d+offset16],%s
Exchange-and-add a 32-bit value at the specified location.