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, 123 insertions, 0 deletions

diff --git a/tools/bpf/Makefile b/tools/bpf/Makefile
new file mode 100644
index 000000000..9c19e81f3
--- /dev/null
+++ b/tools/bpf/Makefile
@@ -0,0 +1,123 @@
+# SPDX-License-Identifier: GPL-2.0
+include ../scripts/Makefile.include
+
+prefix ?= /usr/local
+
+LEX = flex
+YACC = bison
+MAKE = make
+INSTALL ?= install
+
+CFLAGS += -Wall -O2
+CFLAGS += -D__EXPORTED_HEADERS__ -I$(srctree)/tools/include/uapi \
+	  -I$(srctree)/tools/include
+CFLAGS += $(EXTRA_CFLAGS)
+
+# This will work when bpf is built in tools env. where srctree
+# isn't set and when invoked from selftests build, where srctree
+# is set to ".". building_out_of_srctree is undefined for in srctree
+# builds
+ifeq ($(srctree),)
+update_srctree := 1
+endif
+ifndef building_out_of_srctree
+update_srctree := 1
+endif
+ifeq ($(update_srctree),1)
+srctree := $(patsubst %/,%,$(dir $(CURDIR)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+endif
+
+FEATURE_USER = .bpf
+FEATURE_TESTS = libbfd disassembler-four-args disassembler-init-styled
+FEATURE_DISPLAY = libbfd
+
+check_feat := 1
+NON_CHECK_FEAT_TARGETS := clean bpftool_clean resolve_btfids_clean
+ifdef MAKECMDGOALS
+ifeq ($(filter-out $(NON_CHECK_FEAT_TARGETS),$(MAKECMDGOALS)),)
+  check_feat := 0
+endif
+endif
+
+ifeq ($(check_feat),1)
+ifeq ($(FEATURES_DUMP),)
+include $(srctree)/tools/build/Makefile.feature
+else
+include $(FEATURES_DUMP)
+endif
+endif
+
+ifeq ($(feature-disassembler-four-args), 1)
+CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
+endif
+ifeq ($(feature-disassembler-init-styled), 1)
+CFLAGS += -DDISASM_INIT_STYLED
+endif
+
+$(OUTPUT)%.yacc.c: $(srctree)/tools/bpf/%.y
+	$(QUIET_BISON)$(YACC) -o $@ -d $<
+
+$(OUTPUT)%.lex.c: $(srctree)/tools/bpf/%.l
+	$(QUIET_FLEX)$(LEX) -o $@ $<
+
+$(OUTPUT)%.o: $(srctree)/tools/bpf/%.c
+	$(QUIET_CC)$(CC) $(CFLAGS) -c -o $@ $<
+
+$(OUTPUT)%.yacc.o: $(OUTPUT)%.yacc.c
+	$(QUIET_CC)$(CC) $(CFLAGS) -c -o $@ $<
+$(OUTPUT)%.lex.o: $(OUTPUT)%.lex.c
+	$(QUIET_CC)$(CC) $(CFLAGS) -c -o $@ $<
+
+PROGS = $(OUTPUT)bpf_jit_disasm $(OUTPUT)bpf_dbg $(OUTPUT)bpf_asm
+
+all: $(PROGS) bpftool
+
+$(OUTPUT)bpf_jit_disasm: CFLAGS += -DPACKAGE='bpf_jit_disasm'
+$(OUTPUT)bpf_jit_disasm: $(OUTPUT)bpf_jit_disasm.o
+	$(QUIET_LINK)$(CC) $(CFLAGS) -o $@ $^ -lopcodes -lbfd -ldl
+
+$(OUTPUT)bpf_dbg: $(OUTPUT)bpf_dbg.o
+	$(QUIET_LINK)$(CC) $(CFLAGS) -o $@ $^ -lreadline
+
+$(OUTPUT)bpf_asm: $(OUTPUT)bpf_asm.o $(OUTPUT)bpf_exp.yacc.o $(OUTPUT)bpf_exp.lex.o
+	$(QUIET_LINK)$(CC) $(CFLAGS) -o $@ $^
+
+$(OUTPUT)bpf_exp.lex.c: $(OUTPUT)bpf_exp.yacc.c
+$(OUTPUT)bpf_exp.yacc.o: $(OUTPUT)bpf_exp.yacc.c
+$(OUTPUT)bpf_exp.lex.o: $(OUTPUT)bpf_exp.lex.c
+
+clean: bpftool_clean resolve_btfids_clean
+	$(call QUIET_CLEAN, bpf-progs)
+	$(Q)$(RM) -r -- $(OUTPUT)*.o $(OUTPUT)bpf_jit_disasm $(OUTPUT)bpf_dbg \
+	       $(OUTPUT)bpf_asm $(OUTPUT)bpf_exp.yacc.* $(OUTPUT)bpf_exp.lex.*
+	$(call QUIET_CLEAN, core-gen)
+	$(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.bpf
+	$(Q)$(RM) -r -- $(OUTPUT)feature
+
+install: $(PROGS) bpftool_install
+	$(call QUIET_INSTALL, bpf_jit_disasm)
+	$(Q)$(INSTALL) -m 0755 -d $(DESTDIR)$(prefix)/bin
+	$(Q)$(INSTALL) $(OUTPUT)bpf_jit_disasm $(DESTDIR)$(prefix)/bin/bpf_jit_disasm
+	$(call QUIET_INSTALL, bpf_dbg)
+	$(Q)$(INSTALL) $(OUTPUT)bpf_dbg $(DESTDIR)$(prefix)/bin/bpf_dbg
+	$(call QUIET_INSTALL, bpf_asm)
+	$(Q)$(INSTALL) $(OUTPUT)bpf_asm $(DESTDIR)$(prefix)/bin/bpf_asm
+
+bpftool:
+	$(call descend,bpftool)
+
+bpftool_install:
+	$(call descend,bpftool,install)
+
+bpftool_clean:
+	$(call descend,bpftool,clean)
+
+resolve_btfids:
+	$(call descend,resolve_btfids)
+
+resolve_btfids_clean:
+	$(call descend,resolve_btfids,clean)
+
+.PHONY: all install clean bpftool bpftool_install bpftool_clean \
+	resolve_btfids resolve_btfids_clean