ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 163 insertions, 0 deletions

diff --git a/tools/perf/tests/kmod-path.c b/tools/perf/tests/kmod-path.c
new file mode 100644
index 000000000..dfe1bd5da
--- /dev/null
+++ b/tools/perf/tests/kmod-path.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include "tests.h"
+#include "dso.h"
+#include "debug.h"
+#include "event.h"
+
+static int test(const char *path, bool alloc_name, bool kmod,
+		int comp, const char *name)
+{
+	struct kmod_path m;
+
+	memset(&m, 0x0, sizeof(m));
+
+	TEST_ASSERT_VAL("kmod_path__parse",
+			!__kmod_path__parse(&m, path, alloc_name));
+
+	pr_debug("%s - alloc name %d, kmod %d, comp %d, name '%s'\n",
+		 path, alloc_name, m.kmod, m.comp, m.name);
+
+	TEST_ASSERT_VAL("wrong kmod", m.kmod == kmod);
+	TEST_ASSERT_VAL("wrong comp", m.comp == comp);
+
+	if (name)
+		TEST_ASSERT_VAL("wrong name", m.name && !strcmp(name, m.name));
+	else
+		TEST_ASSERT_VAL("wrong name", !m.name);
+
+	free(m.name);
+	return 0;
+}
+
+static int test_is_kernel_module(const char *path, int cpumode, bool expect)
+{
+	TEST_ASSERT_VAL("is_kernel_module",
+			(!!is_kernel_module(path, cpumode)) == (!!expect));
+	pr_debug("%s (cpumode: %d) - is_kernel_module: %s\n",
+			path, cpumode, expect ? "true" : "false");
+	return 0;
+}
+
+#define T(path, an, k, c, n) \
+	TEST_ASSERT_VAL("failed", !test(path, an, k, c, n))
+
+#define M(path, c, e) \
+	TEST_ASSERT_VAL("failed", !test_is_kernel_module(path, c, e))
+
+static int test__kmod_path__parse(struct test_suite *t __maybe_unused, int subtest __maybe_unused)
+{
+	/* path                alloc_name  kmod  comp   name   */
+	T("/xxxx/xxxx/x-x.ko", true      , true, 0    , "[x_x]");
+	T("/xxxx/xxxx/x-x.ko", false     , true, 0    , NULL   );
+	T("/xxxx/xxxx/x-x.ko", true      , true, 0    , "[x_x]");
+	T("/xxxx/xxxx/x-x.ko", false     , true, 0    , NULL   );
+	M("/xxxx/xxxx/x-x.ko", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);
+	M("/xxxx/xxxx/x-x.ko", PERF_RECORD_MISC_KERNEL, true);
+	M("/xxxx/xxxx/x-x.ko", PERF_RECORD_MISC_USER, false);
+
+#ifdef HAVE_ZLIB_SUPPORT
+	/* path                alloc_name   kmod  comp  name  */
+	T("/xxxx/xxxx/x.ko.gz", true     , true, 1   , "[x]");
+	T("/xxxx/xxxx/x.ko.gz", false    , true, 1   , NULL );
+	T("/xxxx/xxxx/x.ko.gz", true     , true, 1   , "[x]");
+	T("/xxxx/xxxx/x.ko.gz", false    , true, 1   , NULL );
+	M("/xxxx/xxxx/x.ko.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);
+	M("/xxxx/xxxx/x.ko.gz", PERF_RECORD_MISC_KERNEL, true);
+	M("/xxxx/xxxx/x.ko.gz", PERF_RECORD_MISC_USER, false);
+
+	/* path              alloc_name  kmod   comp  name  */
+	T("/xxxx/xxxx/x.gz", true      , false, 1   , "x.gz");
+	T("/xxxx/xxxx/x.gz", false     , false, 1   , NULL  );
+	T("/xxxx/xxxx/x.gz", true      , false, 1   , "x.gz");
+	T("/xxxx/xxxx/x.gz", false     , false, 1   , NULL  );
+	M("/xxxx/xxxx/x.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("/xxxx/xxxx/x.gz", PERF_RECORD_MISC_KERNEL, false);
+	M("/xxxx/xxxx/x.gz", PERF_RECORD_MISC_USER, false);
+
+	/* path   alloc_name  kmod   comp  name   */
+	T("x.gz", true      , false, 1   , "x.gz");
+	T("x.gz", false     , false, 1   , NULL  );
+	T("x.gz", true      , false, 1   , "x.gz");
+	T("x.gz", false     , false, 1   , NULL  );
+	M("x.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("x.gz", PERF_RECORD_MISC_KERNEL, false);
+	M("x.gz", PERF_RECORD_MISC_USER, false);
+
+	/* path      alloc_name  kmod  comp  name  */
+	T("x.ko.gz", true      , true, 1   , "[x]");
+	T("x.ko.gz", false     , true, 1   , NULL );
+	T("x.ko.gz", true      , true, 1   , "[x]");
+	T("x.ko.gz", false     , true, 1   , NULL );
+	M("x.ko.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);
+	M("x.ko.gz", PERF_RECORD_MISC_KERNEL, true);
+	M("x.ko.gz", PERF_RECORD_MISC_USER, false);
+#endif
+
+	/* path            alloc_name  kmod  comp   name           */
+	T("[test_module]", true      , true, false, "[test_module]");
+	T("[test_module]", false     , true, false, NULL           );
+	T("[test_module]", true      , true, false, "[test_module]");
+	T("[test_module]", false     , true, false, NULL           );
+	M("[test_module]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);
+	M("[test_module]", PERF_RECORD_MISC_KERNEL, true);
+	M("[test_module]", PERF_RECORD_MISC_USER, false);
+
+	/* path            alloc_name  kmod  comp   name           */
+	T("[test.module]", true      , true, false, "[test.module]");
+	T("[test.module]", false     , true, false, NULL           );
+	T("[test.module]", true      , true, false, "[test.module]");
+	T("[test.module]", false     , true, false, NULL           );
+	M("[test.module]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);
+	M("[test.module]", PERF_RECORD_MISC_KERNEL, true);
+	M("[test.module]", PERF_RECORD_MISC_USER, false);
+
+	/* path     alloc_name  kmod   comp   name    */
+	T("[vdso]", true      , false, false, "[vdso]");
+	T("[vdso]", false     , false, false, NULL    );
+	T("[vdso]", true      , false, false, "[vdso]");
+	T("[vdso]", false     , false, false, NULL    );
+	M("[vdso]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("[vdso]", PERF_RECORD_MISC_KERNEL, false);
+	M("[vdso]", PERF_RECORD_MISC_USER, false);
+
+	T("[vdso32]", true      , false, false, "[vdso32]");
+	T("[vdso32]", false     , false, false, NULL      );
+	T("[vdso32]", true      , false, false, "[vdso32]");
+	T("[vdso32]", false     , false, false, NULL      );
+	M("[vdso32]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("[vdso32]", PERF_RECORD_MISC_KERNEL, false);
+	M("[vdso32]", PERF_RECORD_MISC_USER, false);
+
+	T("[vdsox32]", true      , false, false, "[vdsox32]");
+	T("[vdsox32]", false     , false, false, NULL       );
+	T("[vdsox32]", true      , false, false, "[vdsox32]");
+	T("[vdsox32]", false     , false, false, NULL       );
+	M("[vdsox32]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("[vdsox32]", PERF_RECORD_MISC_KERNEL, false);
+	M("[vdsox32]", PERF_RECORD_MISC_USER, false);
+
+	/* path         alloc_name  kmod   comp   name        */
+	T("[vsyscall]", true      , false, false, "[vsyscall]");
+	T("[vsyscall]", false     , false, false, NULL        );
+	T("[vsyscall]", true      , false, false, "[vsyscall]");
+	T("[vsyscall]", false     , false, false, NULL        );
+	M("[vsyscall]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("[vsyscall]", PERF_RECORD_MISC_KERNEL, false);
+	M("[vsyscall]", PERF_RECORD_MISC_USER, false);
+
+	/* path                alloc_name  kmod   comp   name      */
+	T("[kernel.kallsyms]", true      , false, false, "[kernel.kallsyms]");
+	T("[kernel.kallsyms]", false     , false, false, NULL               );
+	T("[kernel.kallsyms]", true      , false, false, "[kernel.kallsyms]");
+	T("[kernel.kallsyms]", false     , false, false, NULL               );
+	M("[kernel.kallsyms]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);
+	M("[kernel.kallsyms]", PERF_RECORD_MISC_KERNEL, false);
+	M("[kernel.kallsyms]", PERF_RECORD_MISC_USER, false);
+
+	return 0;
+}
+
+DEFINE_SUITE("kmod_path__parse", kmod_path__parse);