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, 74 insertions, 0 deletions

diff --git a/tools/perf/tests/demangle-rust-v0-test.c b/tools/perf/tests/demangle-rust-v0-test.c
new file mode 100644
index 000000000..904f966c6
--- /dev/null
+++ b/tools/perf/tests/demangle-rust-v0-test.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+#include "tests.h"
+#include "debug.h"
+#include "symbol.h"
+#include <linux/kernel.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test__demangle_rust(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
+{
+	int ret = TEST_OK;
+	char *buf = NULL;
+	size_t i;
+
+	struct {
+		const char *mangled, *demangled;
+	} test_cases[] = {
+		{ "_RNvMsr_NtCs3ssYzQotkvD_3std4pathNtB5_7PathBuf3newCs15kBYyAo9fc_7mycrate",
+		  "<std::path::PathBuf>::new" },
+		{ "_RNvCs15kBYyAo9fc_7mycrate7example",
+		  "mycrate::example" },
+		{ "_RNvMs_Cs4Cv8Wi1oAIB_7mycrateNtB4_7Example3foo",
+		  "<mycrate::Example>::foo" },
+		{ "_RNvXCs15kBYyAo9fc_7mycrateNtB2_7ExampleNtB2_5Trait3foo",
+		  "<mycrate::Example as mycrate::Trait>::foo" },
+		{ "_RNvMCs7qp2U7fqm6G_7mycrateNtB2_7Example3foo",
+		  "<mycrate::Example>::foo" },
+		{ "_RNvMs_Cs7qp2U7fqm6G_7mycrateNtB4_7Example3bar",
+		  "<mycrate::Example>::bar" },
+		{ "_RNvYNtCs15kBYyAo9fc_7mycrate7ExampleNtB4_5Trait7exampleB4_",
+		  "<mycrate::Example as mycrate::Trait>::example" },
+		{ "_RNCNvCsgStHSCytQ6I_7mycrate4main0B3_",
+		  "mycrate::main::{closure#0}" },
+		{ "_RNCNvCsgStHSCytQ6I_7mycrate4mains_0B3_",
+		  "mycrate::main::{closure#1}" },
+		{ "_RINvCsgStHSCytQ6I_7mycrate7examplelKj1_EB2_",
+		  "mycrate::example::<i32, 1>" },
+		{ "_RINvCs7qp2U7fqm6G_7mycrate7exampleFG0_RL1_hRL0_tEuEB2_",
+		  "mycrate::example::<for<'a, 'b> fn(&'a u8, &'b u16)>",
+		},
+		{ "_RINvCs7qp2U7fqm6G_7mycrate7exampleKy12345678_EB2_",
+		  "mycrate::example::<305419896>" },
+		{ "_RNvNvMCsd9PVOYlP1UU_7mycrateINtB4_7ExamplepKpE3foo14EXAMPLE_STATIC",
+		  "<mycrate::Example<_, _>>::foo::EXAMPLE_STATIC",
+		},
+		{ "_RINvCs7qp2U7fqm6G_7mycrate7exampleAtj8_EB2_",
+		  "mycrate::example::<[u16; 8]>" },
+		{ "_RINvCs7qp2U7fqm6G_7mycrate7exampleNtB2_7ExampleBw_EB2_",
+		  "mycrate::example::<mycrate::Example, mycrate::Example>" },
+		{ "_RINvMsY_NtCseXNvpPnDBDp_3std4pathNtB6_4Path3neweECs7qp2U7fqm6G_7mycrate",
+		  "<std::path::Path>::new::<str>" },
+		{ "_RNvNvNvCs7qp2U7fqm6G_7mycrate7EXAMPLE7___getit5___KEY",
+		  "mycrate::EXAMPLE::__getit::__KEY" },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+		buf = dso__demangle_sym(/*dso=*/NULL, /*kmodule=*/0, test_cases[i].mangled);
+		if (!buf) {
+			pr_debug("FAILED to demangle: \"%s\"\n \"%s\"\n", test_cases[i].mangled,
+				 test_cases[i].demangled);
+			continue;
+		}
+		if (strcmp(buf, test_cases[i].demangled)) {
+			pr_debug("FAILED: %s: %s != %s\n", test_cases[i].mangled,
+				 buf, test_cases[i].demangled);
+			ret = TEST_FAIL;
+		}
+		free(buf);
+	}
+
+	return ret;
+}
+
+DEFINE_SUITE("Demangle Rust", demangle_rust);