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, 66 insertions, 0 deletions

diff --git a/arch/alpha/Makefile b/arch/alpha/Makefile
new file mode 100644
index 000000000..7074602dc
--- /dev/null
+++ b/arch/alpha/Makefile
@@ -0,0 +1,66 @@
+#
+# alpha/Makefile
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+# Copyright (C) 1994 by Linus Torvalds
+#
+
+NM := $(NM) -B
+
+LDFLAGS_vmlinux	:= -static -N #-relax
+CHECKFLAGS	+= -D__alpha__
+cflags-y	:= -pipe -mno-fp-regs -ffixed-8
+cflags-y	+= $(call cc-option, -fno-jump-tables)
+
+cpuflags-$(CONFIG_ALPHA_EV56)		:= -mcpu=ev56
+cpuflags-$(CONFIG_ALPHA_POLARIS)	:= -mcpu=pca56
+cpuflags-$(CONFIG_ALPHA_SX164)		:= -mcpu=pca56
+cpuflags-$(CONFIG_ALPHA_EV6)		:= -mcpu=ev6
+cpuflags-$(CONFIG_ALPHA_EV67)		:= -mcpu=ev67
+# If GENERIC, make sure to turn off any instruction set extensions that
+# the host compiler might have on by default.
+cpuflags-$(CONFIG_ALPHA_GENERIC)	:= -mcpu=ev56 -mtune=ev6
+
+cflags-y				+= $(cpuflags-y)
+
+
+KBUILD_CFLAGS += $(cflags-y)
+
+# For TSUNAMI, we must have the assembler not emulate our instructions.
+# The same is true for IRONGATE, POLARIS, PYXIS.
+# BWX is most important, but we don't really want any emulation ever.
+# Only gas emulates instructions the target does not implement, and only gas
+# understands -mev6.  LLVM's integrated assembler never emulates.
+ifdef CONFIG_AS_IS_GNU
+KBUILD_CFLAGS += -Wa,-mev6
+endif
+
+libs-y				+= arch/alpha/lib/
+
+# export what is needed by arch/alpha/boot/Makefile
+LIBS_Y := $(patsubst %/, %/lib.a, $(libs-y))
+export LIBS_Y
+
+boot := arch/alpha/boot
+
+#Default target when executing make with no arguments
+all boot: $(boot)/vmlinux.gz
+
+$(boot)/vmlinux.gz: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $@
+
+bootimage bootpfile bootpzfile: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+
+archheaders:
+	$(Q)$(MAKE) $(build)=arch/alpha/kernel/syscalls all
+
+define archhelp
+  echo '* boot		- Compressed kernel image (arch/alpha/boot/vmlinux.gz)'
+  echo '  bootimage	- SRM bootable image (arch/alpha/boot/bootimage)'
+  echo '  bootpfile	- BOOTP bootable image (arch/alpha/boot/bootpfile)'
+  echo '  bootpzfile	- compressed kernel BOOTP image (arch/alpha/boot/bootpzfile)'
+endef