arm: eBPF JIT compiler
authorShubham Bansal <illusionist.neo@gmail.com>
Tue, 22 Aug 2017 06:32:33 +0000 (12:02 +0530)
committerDavid S. Miller <davem@davemloft.net>
Tue, 22 Aug 2017 16:26:43 +0000 (09:26 -0700)
commit39c13c204bb1150d401e27d41a9d8b332be47c49
tree5b227810abdecca21fad1181a83b0820efc0c82f
parente2a7c34fb2856fd5306e307e170e3dde358d0dce
arm: eBPF JIT compiler

The JIT compiler emits ARM 32 bit instructions. Currently, It supports
eBPF only. Classic BPF is supported because of the conversion by BPF core.

This patch is essentially changing the current implementation of JIT compiler
of Berkeley Packet Filter from classic to internal with almost all
instructions from eBPF ISA supported except the following
BPF_ALU64 | BPF_DIV | BPF_K
BPF_ALU64 | BPF_DIV | BPF_X
BPF_ALU64 | BPF_MOD | BPF_K
BPF_ALU64 | BPF_MOD | BPF_X
BPF_STX | BPF_XADD | BPF_W
BPF_STX | BPF_XADD | BPF_DW

Implementation is using scratch space to emulate 64 bit eBPF ISA on 32 bit
ARM because of deficiency of general purpose registers on ARM. Currently,
only LITTLE ENDIAN machines are supported in this eBPF JIT Compiler.

Tested on ARMv7 with QEMU by me (Shubham Bansal).

Testing results on ARMv7:

1) test_bpf: Summary: 341 PASSED, 0 FAILED, [312/333 JIT'ed]
2) test_tag: OK (40945 tests)
3) test_progs: Summary: 30 PASSED, 0 FAILED
4) test_lpm: OK
5) test_lru_map: OK

Above tests are all done with following flags enabled discreatly.

1) bpf_jit_enable=1
a) CONFIG_FRAME_POINTER enabled
b) CONFIG_FRAME_POINTER disabled
2) bpf_jit_enable=1 and bpf_jit_harden=2
a) CONFIG_FRAME_POINTER enabled
b) CONFIG_FRAME_POINTER disabled

See Documentation/networking/filter.txt for more information.

Signed-off-by: Shubham Bansal <illusionist.neo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
arch/arm/Kconfig
arch/arm/net/bpf_jit_32.c
arch/arm/net/bpf_jit_32.h