On 05/03/2018 08:10 AM, Wang YanQing wrote: > The JIT compiler emits ia32 bit instructions. Currently, It supports eBPF > only. Classic BPF is supported because of the conversion by BPF core. > > 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 > > It doesn't support BPF_JMP|BPF_CALL with BPF_PSEUDO_CALL at the moment. > > IA32 has few general purpose registers, EAX|EDX|ECX|EBX|ESI|EDI. I use > EAX|EDX|ECX|EBX as temporary registers to simulate instructions in eBPF > ISA, and allocate ESI|EDI to BPF_REG_AX for constant blinding, all others > eBPF registers, R0-R10, are simulated through scratch space on stack. > > The reasons behind the hardware registers allocation policy are: > 1:MUL need EAX:EDX, shift operation need ECX, so they aren't fit > for general eBPF 64bit register simulation. > 2:We need at least 4 registers to simulate most eBPF ISA operations > on registers operands instead of on register&memory operands. > 3:We need to put BPF_REG_AX on hardware registers, or constant blinding > will degrade jit performance heavily. > > Tested on PC (Intel(R) Core(TM) i5-5200U CPU). > Testing results on i5-5200U: > 1) test_bpf: Summary: 349 PASSED, 0 FAILED, [319/341 JIT'ed] > 2) test_progs: Summary: 83 PASSED, 0 FAILED. > 3) test_lpm: OK > 4) test_lru_map: OK > 5) test_verifier: Summary: 828 PASSED, 0 FAILED. > > Above tests are all done in following two conditions separately: > 1:bpf_jit_enable=1 and bpf_jit_harden=0 > 2:bpf_jit_enable=1 and bpf_jit_harden=2 > > Below are some numbers for this jit implementation: > Note: > I run test_progs in kselftest 100 times continuously for every condition, > the numbers are in format: total/times=avg. > The numbers that test_bpf reports show almost the same relation. > > a:jit_enable=0 and jit_harden=0 b:jit_enable=1 and jit_harden=0 > test_pkt_access:PASS:ipv4:15622/100=156 > test_pkt_access:PASS:ipv4:10674/100=106 > test_pkt_access:PASS:ipv6:9130/100=91 > test_pkt_access:PASS:ipv6:4855/100=48 > test_xdp:PASS:ipv4:240198/100=2401 > test_xdp:PASS:ipv4:138912/100=1389 > test_xdp:PASS:ipv6:137326/100=1373 test_xdp:PASS:ipv6:68542/100=685 > test_l4lb:PASS:ipv4:61100/100=611 test_l4lb:PASS:ipv4:37302/100=373 > test_l4lb:PASS:ipv6:101000/100=1010 test_l4lb:PASS:ipv6:55030/100=550 > > c:jit_enable=1 and jit_harden=2 > test_pkt_access:PASS:ipv4:10558/100=105 > test_pkt_access:PASS:ipv6:5092/100=50 > test_xdp:PASS:ipv4:131902/100=1319 > test_xdp:PASS:ipv6:77932/100=779 > test_l4lb:PASS:ipv4:38924/100=389 > test_l4lb:PASS:ipv6:57520/100=575 > > The numbers show we get 30%~50% improvement. > > See Documentation/networking/filter.txt for more information. > > Signed-off-by: Wang YanQing <udkni...@gmail.com>
Applied to bpf-next, thanks Wang!
