From 70bc793382a0e37ba4e35e4d1a317b280b829a44 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 6 Jan 2022 12:51:56 -0800 Subject: [PATCH] selftests/bpf: Don't rely on preserving volatile in PT_REGS macros in loop3 PT_REGS*() macro on some architectures force-cast struct pt_regs to other types (user_pt_regs, etc) and might drop volatile modifiers, if any. Volatile isn't really required as pt_regs value isn't supposed to change during the BPF program run, so this is correct behavior. But progs/loop3.c relies on that volatile modifier to ensure that loop is preserved. Fix loop3.c by declaring i and sum variables as volatile instead. It preserves the loop and makes the test pass on all architectures (including s390x which is currently broken). Fixes: 3cc31d794097 ("libbpf: Normalize PT_REGS_xxx() macro definitions") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220106205156.955373-1-andrii@kernel.org --- tools/testing/selftests/bpf/progs/loop3.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c index 76e93b31c14b..717dab14322b 100644 --- a/tools/testing/selftests/bpf/progs/loop3.c +++ b/tools/testing/selftests/bpf/progs/loop3.c @@ -12,9 +12,9 @@ char _license[] SEC("license") = "GPL"; SEC("raw_tracepoint/consume_skb") -int while_true(volatile struct pt_regs* ctx) +int while_true(struct pt_regs *ctx) { - __u64 i = 0, sum = 0; + volatile __u64 i = 0, sum = 0; do { i++; sum += PT_REGS_RC(ctx);