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, 115 insertions, 0 deletions

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile
new file mode 100644
index 000000000..6d213d372
--- /dev/null
+++ b/tools/include/nolibc/Makefile
@@ -0,0 +1,115 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for nolibc installation and tests
+include ../../scripts/Makefile.include
+
+# we're in ".../tools/include/nolibc"
+ifeq ($(srctree),)
+srctree := $(patsubst %/tools/include/,%,$(dir $(CURDIR)))
+endif
+
+# when run as make -C tools/ nolibc_<foo> the arch is not set
+ifeq ($(ARCH),)
+include $(srctree)/scripts/subarch.include
+ARCH = $(SUBARCH)
+endif
+
+# OUTPUT is only set when run from the main makefile, otherwise
+# it defaults to this nolibc directory.
+OUTPUT ?= $(CURDIR)/
+
+architectures := alpha arm arm64 loongarch m68k mips openrisc parisc powerpc riscv s390 sh sparc x86
+arch_files := arch.h $(addsuffix .h, $(addprefix arch-, $(architectures)))
+all_files := \
+		alloca.h \
+		assert.h \
+		byteswap.h \
+		compiler.h \
+		crt.h \
+		ctype.h \
+		dirent.h \
+		elf.h \
+		endian.h \
+		err.h \
+		errno.h \
+		fcntl.h \
+		getopt.h \
+		inttypes.h \
+		limits.h \
+		math.h \
+		nolibc.h \
+		poll.h \
+		sched.h \
+		signal.h \
+		stackprotector.h \
+		std.h \
+		stdarg.h \
+		stdbool.h \
+		stddef.h \
+		stdint.h \
+		stdlib.h \
+		string.h \
+		sys.h \
+		sys/auxv.h \
+		sys/ioctl.h \
+		sys/mman.h \
+		sys/mount.h \
+		sys/prctl.h \
+		sys/ptrace.h \
+		sys/random.h \
+		sys/reboot.h \
+		sys/resource.h \
+		sys/select.h \
+		sys/stat.h \
+		sys/syscall.h \
+		sys/sysmacros.h \
+		sys/time.h \
+		sys/timerfd.h \
+		sys/types.h \
+		sys/uio.h \
+		sys/utsname.h \
+		sys/wait.h \
+		time.h \
+		types.h \
+		unistd.h \
+		stdio.h \
+
+
+# install all headers needed to support a bare-metal compiler
+all: headers
+
+install: help
+
+help:
+	@echo "Supported targets under nolibc:"
+	@echo "  all                 call \"headers\""
+	@echo "  clean               clean the sysroot"
+	@echo "  headers             prepare a multi-arch sysroot in \$${OUTPUT}sysroot"
+	@echo "  headers_standalone  like \"headers\", and also install kernel headers"
+	@echo "  help                this help"
+	@echo ""
+	@echo "These targets may also be called from tools as \"make nolibc_<target>\"."
+	@echo ""
+	@echo "Currently using the following variables:"
+	@echo "  ARCH    = $(ARCH)"
+	@echo "  OUTPUT  = $(OUTPUT)"
+	@echo ""
+
+# installs headers for all archs at once.
+headers:
+	$(Q)mkdir -p "$(OUTPUT)sysroot/include"
+	$(Q)cp --parents $(arch_files) $(all_files) "$(OUTPUT)sysroot/include/"
+
+headers_standalone: headers
+	$(Q)$(MAKE) -C $(srctree) headers_install INSTALL_HDR_PATH=$(OUTPUT)sysroot
+
+CFLAGS_s390 := -m64
+CFLAGS := $(CFLAGS_$(ARCH))
+
+headers_check: headers_standalone
+	$(Q)for header in $(filter-out crt.h std.h,$(all_files)); do \
+		$(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -nostdinc -fsyntax-only -x c /dev/null \
+			-I$(or $(objtree),$(srctree))/usr/include -include $$header -include $$header || exit 1; \
+	done
+
+clean:
+	$(call QUIET_CLEAN, nolibc) rm -rf "$(OUTPUT)sysroot"