selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 63 insertions, 0 deletions

diff --git a/tools/perf/tests/mem.c b/tools/perf/tests/mem.c
new file mode 100644
index 000000000..cb3d749e1
--- /dev/null
+++ b/tools/perf/tests/mem.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "util/map_symbol.h"
+#include "util/mem-events.h"
+#include "util/mem-info.h"
+#include "util/symbol.h"
+#include "linux/perf_event.h"
+#include "util/debug.h"
+#include "tests.h"
+#include <string.h>
+
+static int check(union perf_mem_data_src data_src,
+		  const char *string)
+{
+	char out[100];
+	char failure[100];
+	struct mem_info *mi = mem_info__new();
+	int n;
+
+	TEST_ASSERT_VAL("Memory allocation failed", mi);
+	*mem_info__data_src(mi) = data_src;
+	n = perf_mem__snp_scnprintf(out, sizeof out, mi);
+	n += perf_mem__lvl_scnprintf(out + n, sizeof out - n, mi);
+	mem_info__put(mi);
+	scnprintf(failure, sizeof failure, "unexpected %s", out);
+	TEST_ASSERT_VAL(failure, !strcmp(string, out));
+	return 0;
+}
+
+static int test__mem(struct test_suite *text __maybe_unused, int subtest __maybe_unused)
+{
+	int ret = 0;
+	union perf_mem_data_src src;
+
+	memset(&src, 0, sizeof(src));
+
+	src.mem_lvl = PERF_MEM_LVL_HIT;
+	src.mem_lvl_num = 4;
+
+	ret |= check(src, "N/AL4 hit");
+
+	src.mem_remote = 1;
+
+	ret |= check(src, "N/ARemote L4 hit");
+
+	src.mem_lvl = PERF_MEM_LVL_MISS;
+	src.mem_lvl_num = PERF_MEM_LVLNUM_PMEM;
+	src.mem_remote = 0;
+
+	ret |= check(src, "N/APMEM miss");
+
+	src.mem_remote = 1;
+
+	ret |= check(src, "N/ARemote PMEM miss");
+
+	src.mem_snoopx = PERF_MEM_SNOOPX_FWD;
+	src.mem_lvl_num = PERF_MEM_LVLNUM_RAM;
+
+	ret |= check(src , "FwdRemote RAM miss");
+
+	return ret;
+}
+
+DEFINE_SUITE("Test data source output", mem);