selftests/bpf: Add IRQ save/restore tests

Include tests that check for rejection in erroneous cases, like
unbalanced IRQ-disabled counts, within and across subprogs, invalid IRQ
flag state or input to kfuncs, behavior upon overwriting IRQ saved state
on stack, interaction with sleepable kfuncs/helpers, global functions,
and out of order restore. Include some success scenarios as well to
demonstrate usage.

torvalds#123/1   irq/irq_restore_missing_1:OK
torvalds#123/2   irq/irq_restore_missing_2:OK
torvalds#123/3   irq/irq_restore_missing_3:OK
torvalds#123/4   irq/irq_restore_missing_3_minus_2:OK
torvalds#123/5   irq/irq_restore_missing_1_subprog:OK
torvalds#123/6   irq/irq_restore_missing_2_subprog:OK
torvalds#123/7   irq/irq_restore_missing_3_subprog:OK
torvalds#123/8   irq/irq_restore_missing_3_minus_2_subprog:OK
torvalds#123/9   irq/irq_balance:OK
torvalds#123/10  irq/irq_balance_n:OK
torvalds#123/11  irq/irq_balance_subprog:OK
torvalds#123/12  irq/irq_balance_n_subprog:OK
torvalds#123/13  irq/irq_global_subprog:OK
torvalds#123/14  irq/irq_restore_ooo:OK
torvalds#123/15  irq/irq_restore_ooo_3:OK
torvalds#123/16  irq/irq_restore_3_subprog:OK
torvalds#123/17  irq/irq_restore_4_subprog:OK
torvalds#123/18  irq/irq_restore_ooo_3_subprog:OK
torvalds#123/19  irq/irq_restore_invalid:OK
torvalds#123/20  irq/irq_save_invalid:OK
torvalds#123/21  irq/irq_restore_iter:OK
torvalds#123/22  irq/irq_save_iter:OK
torvalds#123/23  irq/irq_flag_overwrite:OK
torvalds#123/24  irq/irq_flag_overwrite_partial:OK
torvalds#123/25  irq/irq_sleepable_helper:OK
torvalds#123/26  irq/irq_sleepable_kfunc:OK
torvalds#123     irq:OK
Summary: 1/26 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>

tools/testing/selftests/bpf/prog_tests/irq.c

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include <irq.skel.h>
+
+void test_irq(void)
+{
+	RUN_TESTS(irq);
+}