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.

#128/1   irq/irq_save_bad_arg:OK
#128/2   irq/irq_restore_bad_arg:OK
#128/3   irq/irq_restore_missing_2:OK
#128/4   irq/irq_restore_missing_3:OK
#128/5   irq/irq_restore_missing_3_minus_2:OK
#128/6   irq/irq_restore_missing_1_subprog:OK
#128/7   irq/irq_restore_missing_2_subprog:OK
#128/8   irq/irq_restore_missing_3_subprog:OK
#128/9   irq/irq_restore_missing_3_minus_2_subprog:OK
#128/10  irq/irq_balance:OK
#128/11  irq/irq_balance_n:OK
#128/12  irq/irq_balance_subprog:OK
#128/13  irq/irq_global_subprog:OK
#128/14  irq/irq_restore_ooo:OK
#128/15  irq/irq_restore_ooo_3:OK
#128/16  irq/irq_restore_3_subprog:OK
#128/17  irq/irq_restore_4_subprog:OK
#128/18  irq/irq_restore_ooo_3_subprog:OK
#128/19  irq/irq_restore_invalid:OK
#128/20  irq/irq_save_invalid:OK
#128/21  irq/irq_restore_iter:OK
#128/22  irq/irq_save_iter:OK
#128/23  irq/irq_flag_overwrite:OK
#128/24  irq/irq_flag_overwrite_partial:OK
#128/25  irq/irq_ooo_refs_array:OK
#128/26  irq/irq_sleepable_helper:OK
#128/27  irq/irq_sleepable_kfunc:OK
#128     irq:OK
Summary: 1/27 PASSED, 0 SKIPPED, 0 FAILED

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

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

@@ -98,6 +98,7 @@
 #include "verifier_xdp_direct_packet_access.skel.h"
 #include "verifier_bits_iter.skel.h"
 #include "verifier_lsm.skel.h"
+#include "irq.skel.h"
 
 #define MAX_ENTRIES 11
 
@@ -225,6 +226,7 @@ void test_verifier_xdp(void)                  { RUN(verifier_xdp); }
 void test_verifier_xdp_direct_packet_access(void) { RUN(verifier_xdp_direct_packet_access); }
 void test_verifier_bits_iter(void) { RUN(verifier_bits_iter); }
 void test_verifier_lsm(void)                  { RUN(verifier_lsm); }
+void test_irq(void)			      { RUN(irq); }
 
 void test_verifier_mtu(void)
 {