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, 78 insertions, 0 deletions

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
new file mode 100644
index 000000000..fc10671c2
--- /dev/null
+++ b/scripts/Kconfig.include
@@ -0,0 +1,78 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# Kconfig helper macros
+
+# Convenient variables
+comma       := ,
+quote       := "
+squote      := '
+empty       :=
+space       := $(empty) $(empty)
+dollar      := $
+right_paren := )
+left_paren  := (
+
+# $(if-success,<command>,<then>,<else>)
+# Return <then> if <command> exits with 0, <else> otherwise.
+if-success = $(shell,{ $(1); } >/dev/null 2>&1 && echo "$(2)" || echo "$(3)")
+
+# $(success,<command>)
+# Return y if <command> exits with 0, n otherwise
+success = $(if-success,$(1),y,n)
+
+# $(failure,<command>)
+# Return n if <command> exits with 0, y otherwise
+failure = $(if-success,$(1),n,y)
+
+# $(cc-option,<flag>)
+# Return y if the compiler supports <flag>, n otherwise
+cc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
+
+# $(ld-option,<flag>)
+# Return y if the linker supports <flag>, n otherwise
+ld-option = $(success,$(LD) -v $(1))
+
+# $(as-instr,<instr>)
+# Return y if the assembler supports <instr>, n otherwise
+as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) $(2) -Wa$(comma)--fatal-warnings -c -x assembler-with-cpp -o /dev/null -)
+as-instr64 = $(as-instr,$(1),$(m64-flag))
+
+# check if $(CC) and $(LD) exist
+$(error-if,$(failure,command -v $(CC)),C compiler '$(CC)' not found)
+$(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
+
+# Get the C compiler name, version, and error out if it is not supported.
+cc-info := $(shell,$(srctree)/scripts/cc-version.sh $(CC))
+$(error-if,$(success,test -z "$(cc-info)"),Sorry$(comma) this C compiler is not supported.)
+cc-name := $(shell,set -- $(cc-info) && echo $1)
+cc-version := $(shell,set -- $(cc-info) && echo $2)
+
+# Get the assembler name, version, and error out if it is not supported.
+as-info := $(shell,$(srctree)/scripts/as-version.sh $(CC) $(CLANG_FLAGS))
+$(error-if,$(success,test -z "$(as-info)"),Sorry$(comma) this assembler is not supported.)
+as-name := $(shell,set -- $(as-info) && echo $1)
+as-version := $(shell,set -- $(as-info) && echo $2)
+
+# Get the linker name, version, and error out if it is not supported.
+ld-info := $(shell,$(srctree)/scripts/ld-version.sh $(LD))
+$(error-if,$(success,test -z "$(ld-info)"),Sorry$(comma) this linker is not supported.)
+ld-name := $(shell,set -- $(ld-info) && echo $1)
+ld-version := $(shell,set -- $(ld-info) && echo $2)
+
+# machine bit flags
+#  $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise.
+#  $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise.
+cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$(1))
+m32-flag := $(cc-option-bit,-m32)
+m64-flag := $(cc-option-bit,-m64)
+
+# Test whether the compiler can link userspace applications
+cc_can_link_user = $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(1))
+
+rustc-version := $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
+rustc-llvm-version := $(shell,$(srctree)/scripts/rustc-llvm-version.sh $(RUSTC))
+
+# $(rustc-option,<flag>)
+# Return y if the Rust compiler supports <flag>, n otherwise
+# If you are testing for unstable features, consider testing RUSTC_VERSION
+# instead, as features may have different completeness while available.
+rustc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(RUSTC) $(1) --crate-type=rlib /dev/null --out-dir=.tmp_$$ -o .tmp_$$/tmp.rlib)