In this patch -
1) Add a new prog "for_each_helper" which tests the basic functionality of
the bpf_for_each helper.

2) Add pyperf600_foreach and strobemeta_foreach to test the performance
of using bpf_for_each instead of a for loop

The results of pyperf600 and strobemeta are as follows:

~strobemeta~

Baseline
    verification time 6808200 usec
    stack depth 496
    processed 592132 insns (limit 1000000) max_states_per_insn 14
    total_states 16018 peak_states 13684 mark_read 3132
    #188 verif_scale_strobemeta:OK (unrolled loop)

Using bpf_for_each
    verification time 31589 usec
    stack depth 96+408
    processed 1630 insns (limit 1000000) max_states_per_insn 4
    total_states 107 peak_states 107 mark_read 60
    #189 verif_scale_strobemeta_foreach:OK

~pyperf600~

Baseline
    verification time 29702486 usec
    stack depth 368
    processed 626838 insns (limit 1000000) max_states_per_insn 7
    total_states 30368 peak_states 30279 mark_read 748
    #182 verif_scale_pyperf600:OK (unrolled loop)

Using bpf_for_each
    verification time 148488 usec
    stack depth 320+40
    processed 10518 insns (limit 1000000) max_states_per_insn 10
    total_states 705 peak_states 517 mark_read 38
    #183 verif_scale_pyperf600_foreach:OK

Using the bpf_for_each helper led to approximately a 100% decrease
in the verification time and in the number of instructions.

Signed-off-by: Joanne Koong <joannekoong@fb.com>

In this patch -
1) Add a new prog "for_each_helper" which tests the basic functionality of
the bpf_for_each helper.

2) Add pyperf600_foreach and strobemeta_foreach to test the performance
of using bpf_for_each instead of a for loop

The results of pyperf600 and strobemeta are as follows:

~strobemeta~

Baseline
    verification time 6808200 usec
    stack depth 496
    processed 592132 insns (limit 1000000) max_states_per_insn 14
    total_states 16018 peak_states 13684 mark_read 3132
    #188 verif_scale_strobemeta:OK (unrolled loop)

Using bpf_for_each
    verification time 31589 usec
    stack depth 96+408
    processed 1630 insns (limit 1000000) max_states_per_insn 4
    total_states 107 peak_states 107 mark_read 60
    #189 verif_scale_strobemeta_foreach:OK

~pyperf600~

Baseline
    verification time 29702486 usec
    stack depth 368
    processed 626838 insns (limit 1000000) max_states_per_insn 7
    total_states 30368 peak_states 30279 mark_read 748
    #182 verif_scale_pyperf600:OK (unrolled loop)

Using bpf_for_each
    verification time 148488 usec
    stack depth 320+40
    processed 10518 insns (limit 1000000) max_states_per_insn 10
    total_states 705 peak_states 517 mark_read 38
    #183 verif_scale_pyperf600_foreach:OK

Using the bpf_for_each helper led to approximately a 100% decrease
in the verification time and in the number of instructions.

Signed-off-by: Joanne Koong <joannekoong@fb.com>