ARRAY_SIZE is defined in several selftests. Remove definitions from
individual test files and include header file for the define instead.
ARRAY_SIZE define is added in a separate patch to prepare for this
change.

Remove ARRAY_SIZE from seccomp_benchmark and pickup the one defined in
kselftest.h.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Instead of depending on "sysctl" being installed, just use "grep -H" for
sysctl status reporting. Additionally report kernel version for easier
comparisons.

Signed-off-by: Kees Cook <keescook@chromium.org>

When running the seccomp benchmark under a test runner, it wouldn't
provide any feedback on progress. Set stdout unbuffered.

Suggested-by: Will Drewry <wad@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

As part of the seccomp benchmarking, include the expectations with
regard to the timing behavior of the constant action bitmaps, and report
inconsistencies better.

Example output with constant action bitmaps on x86:

$ sudo ./seccomp_benchmark 100000000
Current BPF sysctl settings:
net.core.bpf_jit_enable = 1
net.core.bpf_jit_harden = 0
Benchmarking 200000000 syscalls...
129.359381409 - 0.008724424 = 129350656985 (129.4s)
getpid native: 646 ns
264.385890006 - 129.360453229 = 135025436777 (135.0s)
getpid RET_ALLOW 1 filter (bitmap): 675 ns
399.400511893 - 264.387045901 = 135013465992 (135.0s)
getpid RET_ALLOW 2 filters (bitmap): 675 ns
545.872866260 - 399.401718327 = 146471147933 (146.5s)
getpid RET_ALLOW 3 filters (full): 732 ns
696.337101319 - 545.874097681 = 150463003638 (150.5s)
getpid RET_ALLOW 4 filters (full): 752 ns
Estimated total seccomp overhead for 1 bitmapped filter: 29 ns
Estimated total seccomp overhead for 2 bitmapped filters: 29 ns
Estimated total seccomp overhead for 3 full filters: 86 ns
Estimated total seccomp overhead for 4 full filters: 106 ns
Estimated seccomp entry overhead: 29 ns
Estimated seccomp per-filter overhead (last 2 diff): 20 ns
Estimated seccomp per-filter overhead (filters / 4): 19 ns
Expectations:
	native ≤ 1 bitmap (646 ≤ 675): ✔️
	native ≤ 1 filter (646 ≤ 732): ✔️
	per-filter (last 2 diff) ≈ per-filter (filters / 4) (20 ≈ 19): ✔️
	1 bitmapped ≈ 2 bitmapped (29 ≈ 29): ✔️
	entry ≈ 1 bitmapped (29 ≈ 29): ✔️
	entry ≈ 2 bitmapped (29 ≈ 29): ✔️
	native + entry + (per filter * 4) ≈ 4 filters total (755 ≈ 752): ✔️

[YiFei: Changed commit message to show stats for this patch series]
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/1b61df3db85c5f7f1b9202722c45e7b39df73ef2.1602431034.git.yifeifz2@illinois.edu

The seccomp benchmark calibration loop did not need to take so long.
Instead, use a simple 1 second timeout and multiply up to target. It
does not need to be accurate.

Signed-off-by: Kees Cook <keescook@chromium.org>

It's useful to see how much (at a minimum) each filter adds to the
syscall overhead. Add additional calculations.

Signed-off-by: Kees Cook <keescook@chromium.org>

This attempts to produce a comparison between native getpid() and a
RET_ALLOW-filtered getpid(), to measure the overhead cost of using
seccomp().

Signed-off-by: Kees Cook <keescook@chromium.org>