selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/tools/perf/tests/demangle-java-test.c b/tools/perf/tests/demangle-java-test.c
new file mode 100644
index 000000000..0fb3e5a4a
--- /dev/null
+++ b/tools/perf/tests/demangle-java-test.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <linux/kernel.h>
+#include "debug.h"
+#include "symbol.h"
+#include "tests.h"
+
+static int test__demangle_java(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[] = {
+		{ "Ljava/lang/StringLatin1;equals([B[B)Z",
+		  "java.lang.StringLatin1.equals(byte[], byte[])" },
+		{ "Ljava/util/zip/ZipUtils;CENSIZ([BI)J",
+		  "java.util.zip.ZipUtils.CENSIZ(byte[], int)" },
+		{ "Ljava/util/regex/Pattern$BmpCharProperty;match(Ljava/util/regex/Matcher;ILjava/lang/CharSequence;)Z",
+		  "java.util.regex.Pattern$BmpCharProperty.match(java.util.regex.Matcher, int, java.lang.CharSequence)" },
+		{ "Ljava/lang/AbstractStringBuilder;appendChars(Ljava/lang/String;II)V",
+		  "java.lang.AbstractStringBuilder.appendChars(java.lang.String, int, int)" },
+		{ "Ljava/lang/Object;<init>()V",
+		  "java.lang.Object<init>()" },
+	};
+
+	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 Java", demangle_java);