Merge branch 'correct-recent-gcc-incompatible-changes'

Cupertino Miranda says:

====================
Correct recent GCC incompatible changes.

Hi everyone,

Apologies for the previous patches which did not include a cover letter.
My wish was to send 3 indepepdent patches but after the initial mistake lets keep
this as a series although they are all independent from themselves.

The changes in this patch series is related to recovering GCC support to
build the selftests.
A few tests and a makefile change have broken the support for GCC in the
last few months.

Looking forward to your comments.

Best regards,
Cupertino
====================

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Andrii Nakryiko <[e-mail]>

tools/testing/selftests/bpf/Makefile

···
 progs/test_sk_lookup.c-CFLAGS := -fno-strict-aliasing
 progs/timer_crash.c-CFLAGS := -fno-strict-aliasing
 progs/test_global_func9.c-CFLAGS := -fno-strict-aliasing
+progs/verifier_nocsr.c-CFLAGS := -fno-strict-aliasing
 
 ifneq ($(LLVM),)
 # Silence some warnings when compiled with clang

tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c

···
 SEC("tc")
 int tailcall_bpf2bpf_hierarchy_2(struct __sk_buff *skb)
 {
-	volatile int ret = 0;
+	int ret = 0;
 
 	subprog_tail0(skb);
 	subprog_tail1(skb);
 
-	asm volatile (""::"r+"(ret));
+	__sink(ret);
 	return (count1 << 16) | count0;
 }
 

tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c

···
 SEC("tc")
 int tailcall_bpf2bpf_hierarchy_3(struct __sk_buff *skb)
 {
-	volatile int ret = 0;
+	int ret = 0;
 
 	bpf_tail_call_static(skb, &jmp_table0, 0);
 
-	asm volatile (""::"r+"(ret));
+	__sink(ret);
 	return ret;
 }