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authorAlexei Starovoitov <ast@kernel.org>2023-02-14 15:50:51 -0800
committerMartin KaFai Lau <martin.lau@kernel.org>2023-02-15 09:24:59 -0800
commit62d101d5f422cde39b269f7eb4cbbe2f1e26f9d4 (patch)
tree59b808098f150e0f6ac994adcb30f2bae2c271b0
parent5e53e5c7edc6d69b8cb48b3b370cfe531e4b4132 (diff)
selftests/bpf: Fix map_kptr test.
The compiler is optimizing out majority of unref_ptr read/writes, so the test wasn't testing much. For example, one could delete '__kptr' tag from 'struct prog_test_ref_kfunc __kptr *unref_ptr;' and the test would still "pass". Convert it to volatile stores. Confirmed by comparing bpf asm before/after. Fixes: 2cbc469a6fc3 ("selftests/bpf: Add C tests for kptr") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Stanislav Fomichev <sdf@google.com> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20230214235051.22938-1-alexei.starovoitov@gmail.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
-rw-r--r--tools/testing/selftests/bpf/progs/map_kptr.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/tools/testing/selftests/bpf/progs/map_kptr.c b/tools/testing/selftests/bpf/progs/map_kptr.c
index eb8217803493..228ec45365a8 100644
--- a/tools/testing/selftests/bpf/progs/map_kptr.c
+++ b/tools/testing/selftests/bpf/progs/map_kptr.c
@@ -62,21 +62,23 @@ extern struct prog_test_ref_kfunc *
bpf_kfunc_call_test_kptr_get(struct prog_test_ref_kfunc **p, int a, int b) __ksym;
extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;
+#define WRITE_ONCE(x, val) ((*(volatile typeof(x) *) &(x)) = (val))
+
static void test_kptr_unref(struct map_value *v)
{
struct prog_test_ref_kfunc *p;
p = v->unref_ptr;
/* store untrusted_ptr_or_null_ */
- v->unref_ptr = p;
+ WRITE_ONCE(v->unref_ptr, p);
if (!p)
return;
if (p->a + p->b > 100)
return;
/* store untrusted_ptr_ */
- v->unref_ptr = p;
+ WRITE_ONCE(v->unref_ptr, p);
/* store NULL */
- v->unref_ptr = NULL;
+ WRITE_ONCE(v->unref_ptr, NULL);
}
static void test_kptr_ref(struct map_value *v)
@@ -85,7 +87,7 @@ static void test_kptr_ref(struct map_value *v)
p = v->ref_ptr;
/* store ptr_or_null_ */
- v->unref_ptr = p;
+ WRITE_ONCE(v->unref_ptr, p);
if (!p)
return;
if (p->a + p->b > 100)
@@ -99,7 +101,7 @@ static void test_kptr_ref(struct map_value *v)
return;
}
/* store ptr_ */
- v->unref_ptr = p;
+ WRITE_ONCE(v->unref_ptr, p);
bpf_kfunc_call_test_release(p);
p = bpf_kfunc_call_test_acquire(&(unsigned long){0});