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, 121 insertions, 0 deletions

diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h
new file mode 100644
index 000000000..714256228
--- /dev/null
+++ b/tools/include/nolibc/crt.h
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * C Run Time support for NOLIBC
+ * Copyright (C) 2023 Zhangjin Wu <falcon@tinylab.org>
+ */
+
+#ifndef _NOLIBC_CRT_H
+#define _NOLIBC_CRT_H
+
+#define __nolibc_arg_to_reg(_a)									\
+	__builtin_choose_expr(__builtin_classify_type(_a) == __builtin_classify_type(NULL),	\
+			      (unsigned long)(_a), (_a))
+
+#ifndef NOLIBC_NO_RUNTIME
+
+#include "compiler.h"
+
+char **environ __attribute__((weak));
+const unsigned long *_auxv __attribute__((weak));
+
+void _start(void);
+static void __stack_chk_init(void);
+static void exit(int);
+static char *strrchr(const char *s, int c);
+
+extern void (*const __preinit_array_start[])(int, char **, char**) __attribute__((weak));
+extern void (*const __preinit_array_end[])(int, char **, char**) __attribute__((weak));
+
+extern void (*const __init_array_start[])(int, char **, char**) __attribute__((weak));
+extern void (*const __init_array_end[])(int, char **, char**) __attribute__((weak));
+
+extern void (*const __fini_array_start[])(void) __attribute__((weak));
+extern void (*const __fini_array_end[])(void) __attribute__((weak));
+
+#ifndef NOLIBC_IGNORE_ERRNO
+extern char *program_invocation_name __attribute__((weak));
+extern char *program_invocation_short_name __attribute__((weak));
+
+static __inline__
+char *__nolibc_program_invocation_short_name(char *long_name)
+{
+
+	char *short_name;
+
+	short_name = strrchr(long_name, '/');
+	if (!short_name || !short_name[0])
+		return long_name;
+
+	return short_name + 1;
+}
+#endif /* NOLIBC_IGNORE_ERRNO */
+
+void _start_c(long *sp);
+__attribute__((weak,used)) __nolibc_no_sanitize_undefined __nolibc_no_stack_protector
+void _start_c(long *sp)
+{
+	long argc;
+	char **argv;
+	char **envp;
+	int exitcode;
+	void (* const *ctor_func)(int, char **, char **);
+	void (* const *dtor_func)(void);
+	const unsigned long *auxv;
+	/* silence potential warning: conflicting types for 'main' */
+	int _nolibc_main(int, char **, char **) __asm__ ("main");
+
+	/* initialize stack protector */
+	__stack_chk_init();
+
+	/*
+	 * sp  :    argc          <-- argument count, required by main()
+	 * argv:    argv[0]       <-- argument vector, required by main()
+	 *          argv[1]
+	 *          ...
+	 *          argv[argc-1]
+	 *          null
+	 * environ: environ[0]    <-- environment variables, required by main() and getenv()
+	 *          environ[1]
+	 *          ...
+	 *          null
+	 * _auxv:   _auxv[0]      <-- auxiliary vector, required by getauxval()
+	 *          _auxv[1]
+	 *          ...
+	 *          null
+	 */
+
+	/* assign argc and argv */
+	argc = *sp;
+	argv = (void *)(sp + 1);
+
+	/* find environ */
+	environ = envp = argv + argc + 1;
+
+	/* find _auxv */
+	for (auxv = (void *)envp; *auxv++;)
+		__asm__("");
+	_auxv = auxv;
+
+#ifndef NOLIBC_IGNORE_ERRNO
+	if (argc > 0 && argv[0]) {
+		program_invocation_name = argv[0];
+		program_invocation_short_name = __nolibc_program_invocation_short_name(argv[0]);
+	}
+#endif /* NOLIBC_IGNORE_ERRNO */
+
+	for (ctor_func = __preinit_array_start; ctor_func < __preinit_array_end; ctor_func++)
+		(*ctor_func)(argc, argv, envp);
+	for (ctor_func = __init_array_start; ctor_func < __init_array_end; ctor_func++)
+		(*ctor_func)(argc, argv, envp);
+
+	/* go to application */
+	exitcode = _nolibc_main(argc, argv, envp);
+
+	for (dtor_func = __fini_array_end; dtor_func > __fini_array_start;)
+		(*--dtor_func)();
+
+	exit(exitcode);
+}
+
+#endif /* NOLIBC_NO_RUNTIME */
+#endif /* _NOLIBC_CRT_H */