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selftests/bpf: Don't rely on preserving volatile in PT_REGS macros in loop3

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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: 3cc31d7940 ("libbpf: Normalize PT_REGS_xxx() macro definitions")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220106205156.955373-1-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2022-01-06 12:51:56 -08:00 committed by Daniel Borkmann
parent 1372d34ccf
commit 70bc793382
1 changed files with 2 additions and 2 deletions
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4
tools/testing/selftests/bpf/progs/loop3.c
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@ -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);