selftests/bpf: Drop duplicate max/min definitions

Drop duplicate macros min() and MAX() definitions in prog_tests and use
MIN() or MAX() in sys/param.h instead.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/1ae276da9925c2de59b5bdc93b693b4c243e692e.1649462033.git.geliang.tang@suse.com

selftests/bpf: Normalize selftest entry points

Ensure that all test entry points are global void functions with no
input arguments. Mark few subtest entry points as static.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211022223228.99920-2-andrii@kernel.org

selftest/bpf: Extend the bpf_snprintf() test for "%c".

This patch adds various "positive" patterns for "%c" and two "negative"
patterns for wide character.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210814015718.42704-5-kuniyu@amazon.co.jp

selftests/bpf: Fix the snprintf test

The BPF program for the snprintf selftest runs on all syscall entries.
On busy multicore systems this can cause concurrency issues.

For example it was observed that sometimes the userspace part of the
test reads " 4 0000" instead of " 4 000" (extra '0' at the end)
which seems to happen just before snprintf on another core sets
end[-1] = '\0'.

This patch adds a pid filter to the test to ensure that no
bpf_snprintf() will write over the test's output buffers while the
userspace reads the values.

Fixes: c2e39c6bdc7e ("selftests/bpf: Add a series of tests for bpf_snprintf")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210428152501.1024509-1-revest@chromium.org

selftests/bpf: Add a series of tests for bpf_snprintf

The "positive" part tests all format specifiers when things go well.

The "negative" part makes sure that incorrect format strings fail at
load time.

Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-7-revest@chromium.org