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, 77 insertions, 0 deletions

diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile
new file mode 100644
index 000000000..4c14a0217
--- /dev/null
+++ b/arch/xtensa/Makefile
@@ -0,0 +1,77 @@
+#
+# 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) 2001 - 2005  Tensilica Inc.
+# Copyright (C) 2014 Cadence Design Systems Inc.
+#
+# This file is included by the global makefile so that you can add your own
+# architecture-specific flags and dependencies.
+
+# Core configuration.
+# (Use VAR=<xtensa_config> to use another default compiler.)
+
+variant-y := $(CONFIG_XTENSA_VARIANT_NAME)
+
+VARIANT = $(variant-y)
+
+ifneq ($(VARIANT),)
+  ifdef cross_compiling
+    ifndef CROSS_COMPILE
+      CROSS_COMPILE = xtensa_$(VARIANT)-
+    endif
+  endif
+endif
+
+# Platform configuration
+
+platform-$(CONFIG_XTENSA_PLATFORM_XT2000)	:= xt2000
+platform-$(CONFIG_XTENSA_PLATFORM_ISS)		:= iss
+platform-$(CONFIG_XTENSA_PLATFORM_XTFPGA)	:= xtfpga
+
+# temporarily until string.h is fixed
+KBUILD_CFLAGS += -ffreestanding -D__linux__
+KBUILD_CFLAGS += -pipe -mlongcalls -mtext-section-literals
+KBUILD_CFLAGS += $(call cc-option,-mforce-no-pic,)
+KBUILD_CFLAGS += $(call cc-option,-mno-serialize-volatile,)
+KBUILD_CFLAGS += $(call cc-option,-mno-fdpic,)
+ifneq ($(CONFIG_KERNEL_ABI_CALL0),)
+KBUILD_CFLAGS += -mabi=call0
+KBUILD_AFLAGS += -mabi=call0
+endif
+
+KBUILD_AFLAGS += -mlongcalls -mtext-section-literals
+KBUILD_AFLAGS += $(call cc-option,-mno-fdpic,)
+
+KBUILD_LDFLAGS += -m elf32xtensa
+
+ifneq ($(CONFIG_LD_NO_RELAX),)
+KBUILD_LDFLAGS += --no-relax
+endif
+
+CHECKFLAGS += -D$(if $(CONFIG_CPU_BIG_ENDIAN),__XTENSA_EB__,__XTENSA_EL__)
+
+vardirs := $(patsubst %,arch/xtensa/variants/%/,$(variant-y))
+plfdirs := $(patsubst %,arch/xtensa/platforms/%/,$(platform-y))
+
+KBUILD_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(vardirs) $(plfdirs))
+
+KBUILD_DEFCONFIG := iss_defconfig
+
+libs-y		+= arch/xtensa/lib/
+
+boot		:= arch/xtensa/boot
+
+all Image zImage uImage xipImage: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $@
+
+archheaders:
+	$(Q)$(MAKE) $(build)=arch/xtensa/kernel/syscalls all
+
+define archhelp
+  @echo '* Image       - Kernel ELF image with reset vector'
+  @echo '* zImage      - Compressed kernel image (arch/xtensa/boot/images/zImage.*)'
+  @echo '* uImage      - U-Boot wrapped image'
+  @echo '  xipImage    - XIP image'
+endef