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, 93 insertions, 0 deletions

diff --git a/tools/include/nolibc/compiler.h b/tools/include/nolibc/compiler.h
new file mode 100644
index 000000000..f2d7a81d0
--- /dev/null
+++ b/tools/include/nolibc/compiler.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * NOLIBC compiler support header
+ * Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
+ */
+#ifndef _NOLIBC_COMPILER_H
+#define _NOLIBC_COMPILER_H
+
+#if defined(__has_attribute)
+#  define __nolibc_has_attribute(attr) __has_attribute(attr)
+#else
+#  define __nolibc_has_attribute(attr) 0
+#endif
+
+#if defined(__has_feature)
+#  define __nolibc_has_feature(feature) __has_feature(feature)
+#else
+#  define __nolibc_has_feature(feature) 0
+#endif
+
+#define __nolibc_aligned(alignment) __attribute__((aligned(alignment)))
+#define __nolibc_aligned_as(type) __nolibc_aligned(__alignof__(type))
+
+#if __nolibc_has_attribute(naked)
+#  define __nolibc_entrypoint __attribute__((naked))
+#  define __nolibc_entrypoint_epilogue()
+#else
+#  define __nolibc_entrypoint __attribute__((optimize("Os", "omit-frame-pointer")))
+#  define __nolibc_entrypoint_epilogue() __builtin_unreachable()
+#endif /* __nolibc_has_attribute(naked) */
+
+#if defined(__SSP__) || defined(__SSP_STRONG__) || defined(__SSP_ALL__) || defined(__SSP_EXPLICIT__)
+
+#define _NOLIBC_STACKPROTECTOR
+
+#endif /* defined(__SSP__) ... */
+
+#if __nolibc_has_attribute(no_stack_protector)
+#  define __nolibc_no_stack_protector __attribute__((no_stack_protector))
+#else
+#  define __nolibc_no_stack_protector __attribute__((__optimize__("-fno-stack-protector")))
+#endif /* __nolibc_has_attribute(no_stack_protector) */
+
+#if __nolibc_has_attribute(__fallthrough__)
+#  define __nolibc_fallthrough do { } while (0); __attribute__((__fallthrough__))
+#else
+#  define __nolibc_fallthrough do { } while (0)
+#endif /* __nolibc_has_attribute(fallthrough) */
+
+#if defined(__STDC_VERSION__)
+#  define __nolibc_stdc_version __STDC_VERSION__
+#else
+#  define __nolibc_stdc_version 0
+#endif
+
+#define __nolibc_version(_major, _minor, _patch) ((_major) * 10000 + (_minor) * 100 + (_patch))
+
+#ifdef __GNUC__
+#  define __nolibc_gnuc_version \
+		__nolibc_version(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
+#else
+#  define __nolibc_gnuc_version 0
+#endif /* __GNUC__ */
+
+#ifdef __clang__
+#  define __nolibc_clang_version \
+		__nolibc_version(__clang_major__, __clang_minor__, __clang_patchlevel__)
+#else
+#  define __nolibc_clang_version 0
+#endif /* __clang__ */
+
+#if __nolibc_stdc_version >= 201112L || \
+	__nolibc_gnuc_version >= __nolibc_version(4, 6, 0) || \
+	__nolibc_clang_version >= __nolibc_version(3, 0, 0)
+#  define __nolibc_static_assert(_t) _Static_assert(_t, "")
+#else
+#  define __nolibc_static_assert(_t)
+#endif
+
+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define _NOLIBC_OPTIMIZER_HIDE_VAR(var)	__asm__ ("" : "+r" (var))
+
+#if __nolibc_has_feature(undefined_behavior_sanitizer)
+#  if defined(__clang__)
+#    define __nolibc_no_sanitize_undefined __attribute__((no_sanitize("function")))
+#  else
+#    define __nolibc_no_sanitize_undefined __attribute__((no_sanitize_undefined))
+#  endif
+#else
+#  define __nolibc_no_sanitize_undefined
+#endif
+
+#endif /* _NOLIBC_COMPILER_H */