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, 197 insertions, 0 deletions

diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
new file mode 100644
index 000000000..00d3ba2c4
--- /dev/null
+++ b/arch/mips/vdso/Makefile
@@ -0,0 +1,197 @@
+# SPDX-License-Identifier: GPL-2.0
+# Objects to go into the VDSO.
+
+# Include the generic Makefile to check the built vdso.
+include $(srctree)/lib/vdso/Makefile.include
+
+obj-vdso-y := elf.o sigreturn.o
+
+# Common compiler flags between ABIs.
+ccflags-vdso := \
+	$(filter -I%,$(KBUILD_CFLAGS)) \
+	$(filter -E%,$(KBUILD_CFLAGS)) \
+	$(filter -mmicromips,$(KBUILD_CFLAGS)) \
+	$(filter -march=%,$(KBUILD_CFLAGS)) \
+	$(filter -m%-float,$(KBUILD_CFLAGS)) \
+	$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
+	$(CLANG_FLAGS) \
+	-D__VDSO__
+
+ifndef CONFIG_64BIT
+ccflags-vdso += -DBUILD_VDSO32
+endif
+
+#
+# The -fno-jump-tables flag only prevents the compiler from generating
+# jump tables but does not prevent the compiler from emitting absolute
+# offsets.
+cflags-vdso := $(ccflags-vdso) \
+	$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
+	$(filter -std=%,$(KBUILD_CFLAGS)) \
+	-O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
+	-mrelax-pic-calls $(call cc-option, -mexplicit-relocs) \
+	-fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
+	$(call cc-option, -fno-asynchronous-unwind-tables)
+aflags-vdso := $(ccflags-vdso) \
+	-D__ASSEMBLY__ -Wa,-gdwarf-2
+
+ifneq ($(c-gettimeofday-y),)
+obj-vdso-y += vgettimeofday.o
+CFLAGS_vgettimeofday.o = -include $(c-gettimeofday-y)
+
+# config-n32-o32-env.c prepares the environment to build a 32bit vDSO
+# library on a 64bit kernel.
+# Note: Needs to be included before than the generic library.
+CFLAGS_vgettimeofday-o32.o = -include $(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
+CFLAGS_vgettimeofday-n32.o = -include $(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
+endif
+
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
+
+# VDSO linker flags.
+ldflags-y := -Bsymbolic --no-undefined -soname=linux-vdso.so.1 \
+	$(filter -E%,$(KBUILD_CFLAGS)) -shared \
+	-G 0 --eh-frame-hdr --hash-style=sysv --build-id=sha1 -T
+
+CFLAGS_REMOVE_vdso.o = $(CC_FLAGS_FTRACE)
+
+# Check that we don't have PIC 'jalr t9' calls left
+quiet_cmd_vdso_mips_check = VDSOCHK $@
+      cmd_vdso_mips_check = if $(OBJDUMP) --disassemble $@ | grep -E -h "jalr.*t9" > /dev/null; \
+		       then (echo >&2 "$@: PIC 'jalr t9' calls are not supported"; \
+			     rm -f $@; /bin/false); fi
+
+#
+# Shared build commands.
+#
+
+quiet_cmd_vdsold_and_vdso_check = LD      $@
+      cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check); $(cmd_vdso_mips_check)
+
+quiet_cmd_vdsoas_o_S = AS      $@
+      cmd_vdsoas_o_S = $(CC) $(a_flags) -c -o $@ $<
+
+# Strip rule for the raw .so files
+$(obj)/%.so.raw: OBJCOPYFLAGS := -S
+$(obj)/%.so.raw: $(obj)/%.so.dbg.raw FORCE
+	$(call if_changed,objcopy)
+
+hostprogs := genvdso
+
+quiet_cmd_genvdso = GENVDSO $@
+define cmd_genvdso
+	$(foreach file,$(filter %.raw,$^),cp $(file) $(file:%.raw=%) &&) \
+	$(obj)/genvdso $(<:%.raw=%) $(<:%.dbg.raw=%) $@ $(VDSO_NAME)
+endef
+
+#
+# Build native VDSO.
+#
+
+native-abi := $(filter -mabi=%,$(KBUILD_CFLAGS))
+
+targets += $(obj-vdso-y)
+targets += vdso.lds
+targets += vdso.so.dbg.raw vdso.so.raw
+targets += vdso.so.dbg vdso.so
+targets += vdso-image.c
+
+obj-vdso := $(obj-vdso-y:%.o=$(obj)/%.o)
+
+$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso) $(native-abi)
+$(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi)
+
+$(obj)/vdso.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) $(native-abi)
+
+$(obj)/vdso.so.dbg.raw: $(obj)/vdso.lds $(obj-vdso) FORCE
+	$(call if_changed,vdsold_and_vdso_check)
+
+$(obj)/vdso-image.c: $(obj)/vdso.so.dbg.raw $(obj)/vdso.so.raw \
+                     $(obj)/genvdso FORCE
+	$(call if_changed,genvdso)
+
+obj-y += vdso-image.o
+
+#
+# Build O32 VDSO.
+#
+
+# Define these outside the ifdef to ensure they are picked up by clean.
+targets += $(obj-vdso-y:%.o=%-o32.o)
+targets += vdso-o32.lds
+targets += vdso-o32.so.dbg.raw vdso-o32.so.raw
+targets += vdso-o32.so.dbg vdso-o32.so
+targets += vdso-o32-image.c
+
+ifdef CONFIG_MIPS32_O32
+
+obj-vdso-o32 := $(obj-vdso-y:%.o=$(obj)/%-o32.o)
+
+$(obj-vdso-o32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=32
+$(obj-vdso-o32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=32
+
+$(obj)/%-o32.o: $(src)/%.S FORCE
+	$(call if_changed_dep,vdsoas_o_S)
+
+$(obj)/%-o32.o: $(src)/%.c FORCE
+	$(call cmd,force_checksrc)
+	$(call if_changed_rule,cc_o_c)
+
+$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=32
+$(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
+	$(call if_changed_dep,cpp_lds_S)
+
+$(obj)/vdso-o32.so.dbg.raw: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
+	$(call if_changed,vdsold_and_vdso_check)
+
+$(obj)/vdso-o32-image.c: VDSO_NAME := o32
+$(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg.raw $(obj)/vdso-o32.so.raw \
+                         $(obj)/genvdso FORCE
+	$(call if_changed,genvdso)
+
+obj-y += vdso-o32-image.o
+
+endif
+
+#
+# Build N32 VDSO.
+#
+
+targets += $(obj-vdso-y:%.o=%-n32.o)
+targets += vdso-n32.lds
+targets += vdso-n32.so.dbg.raw vdso-n32.so.raw
+targets += vdso-n32.so.dbg vdso-n32.so
+targets += vdso-n32-image.c
+
+ifdef CONFIG_MIPS32_N32
+
+obj-vdso-n32 := $(obj-vdso-y:%.o=$(obj)/%-n32.o)
+
+$(obj-vdso-n32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=n32
+$(obj-vdso-n32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=n32
+
+$(obj)/%-n32.o: $(src)/%.S FORCE
+	$(call if_changed_dep,vdsoas_o_S)
+
+$(obj)/%-n32.o: $(src)/%.c FORCE
+	$(call cmd,force_checksrc)
+	$(call if_changed_rule,cc_o_c)
+
+$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=n32
+$(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
+	$(call if_changed_dep,cpp_lds_S)
+
+$(obj)/vdso-n32.so.dbg.raw: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
+	$(call if_changed,vdsold_and_vdso_check)
+
+$(obj)/vdso-n32-image.c: VDSO_NAME := n32
+$(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg.raw $(obj)/vdso-n32.so.raw \
+                         $(obj)/genvdso FORCE
+	$(call if_changed,genvdso)
+
+obj-y += vdso-n32-image.o
+
+endif
+
+# FIXME: Need install rule for debug.
+# Needs to deal with dependency for generation of dbg by cmd_genvdso...