From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/objtool/Makefile | 156 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 tools/objtool/Makefile (limited to 'tools/objtool/Makefile') diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile new file mode 100644 index 000000000..a4484fd22 --- /dev/null +++ b/tools/objtool/Makefile @@ -0,0 +1,156 @@ +# SPDX-License-Identifier: GPL-2.0 +include ../scripts/Makefile.include +include ../scripts/Makefile.arch + +ifeq ($(SRCARCH),x86) + BUILD_ORC := y + ARCH_HAS_KLP := y +endif + +ifeq ($(SRCARCH),loongarch) + BUILD_ORC := y +endif + +ifeq ($(ARCH_HAS_KLP),y) + HAVE_XXHASH = $(shell printf "$(pound)include \nXXH3_state_t *state;int main() {}" | \ + $(HOSTCC) $(HOSTCFLAGS) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n) + ifeq ($(HAVE_XXHASH),y) + BUILD_KLP := y + LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \ + -DBUILD_KLP + LIBXXHASH_LIBS := $(shell $(HOSTPKG_CONFIG) libxxhash --libs 2>/dev/null || echo -lxxhash) + endif +endif + +export BUILD_ORC BUILD_KLP + +ifeq ($(srctree),) +srctree := $(patsubst %/,%,$(dir $(CURDIR))) +srctree := $(patsubst %/,%,$(dir $(srctree))) +endif + +RM ?= rm -f + +LIBSUBCMD_DIR = $(srctree)/tools/lib/subcmd/ +ifneq ($(OUTPUT),) + LIBSUBCMD_OUTPUT = $(abspath $(OUTPUT))/libsubcmd +else + LIBSUBCMD_OUTPUT = $(CURDIR)/libsubcmd +endif +LIBSUBCMD = $(LIBSUBCMD_OUTPUT)/libsubcmd.a + +OBJTOOL := $(OUTPUT)objtool +OBJTOOL_IN := $(OBJTOOL)-in.o + +LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) +LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) + +all: $(OBJTOOL) + +WARNINGS := -Werror -Wall -Wextra -Wmissing-prototypes \ + -Wmissing-declarations -Wwrite-strings \ + -Wno-implicit-fallthrough -Wno-sign-compare \ + -Wno-unused-parameter + +INCLUDES := -I$(srctree)/tools/include \ + -I$(srctree)/tools/include/uapi \ + -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \ + -I$(srctree)/tools/arch/$(SRCARCH)/include \ + -I$(srctree)/tools/objtool/include \ + -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \ + -I$(srctree)/tools/lib + +OBJTOOL_CFLAGS := -std=gnu11 -fomit-frame-pointer -O2 -g $(WARNINGS) \ + $(INCLUDES) $(LIBELF_FLAGS) $(LIBXXHASH_CFLAGS) $(HOSTCFLAGS) + +OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(LIBXXHASH_LIBS) $(HOSTLDFLAGS) + +# Allow old libelf to be used: +elfshdr := $(shell echo '$(pound)include ' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - 2>/dev/null | grep elf_getshdr) +OBJTOOL_CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED) + +# Always want host compilation. +HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" + +# +# To support disassembly, objtool needs libopcodes which is provided +# with libbfd (binutils-dev or binutils-devel package). +# +# We check using HOSTCC directly rather than the shared feature framework +# because objtool is a host tool that links against host libraries. +# +# When using shared libraries, -lopcodes is sufficient as dependencies are +# resolved automatically. With static libraries, we must explicitly link +# against libopcodes' dependencies: libbfd, libiberty, and sometimes libz. +# Try each combination and use the first one that succeeds. +# +LIBOPCODES_LIBS := $(shell \ + for libs in "-lopcodes" \ + "-lopcodes -lbfd" \ + "-lopcodes -lbfd -liberty" \ + "-lopcodes -lbfd -liberty -lz"; do \ + echo 'extern void disassemble_init_for_target(void *);' \ + 'int main(void) { disassemble_init_for_target(0); return 0; }' | \ + $(HOSTCC) -xc - -o /dev/null $$libs 2>/dev/null && \ + echo "$$libs" && break; \ + done) + +# Styled disassembler support requires binutils >= 2.39 +HAVE_DISASM_STYLED := $(shell echo '$(pound)include ' | \ + $(HOSTCC) -E -xc - 2>/dev/null | grep -q disassembler_style && echo y) + +BUILD_DISAS := n + +ifneq ($(LIBOPCODES_LIBS),) + BUILD_DISAS := y + OBJTOOL_CFLAGS += -DDISAS -DPACKAGE='"objtool"' + OBJTOOL_LDFLAGS += $(LIBOPCODES_LIBS) +ifeq ($(HAVE_DISASM_STYLED),y) + OBJTOOL_CFLAGS += -DDISASM_INIT_STYLED +endif +endif + +export BUILD_DISAS + +AWK = awk +MKDIR = mkdir + +export srctree OUTPUT CFLAGS SRCARCH AWK +include $(srctree)/tools/build/Makefile.include + +$(OBJTOOL_IN): fixdep $(LIBSUBCMD) FORCE + $(Q)$(CONFIG_SHELL) ./sync-check.sh + $(Q)$(MAKE) $(build)=objtool $(HOST_OVERRIDES) CFLAGS="$(OBJTOOL_CFLAGS)" \ + LDFLAGS="$(OBJTOOL_LDFLAGS)" + + +$(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN) + $(QUIET_LINK)$(HOSTCC) $(OBJTOOL_IN) $(OBJTOOL_LDFLAGS) -o $@ + + +$(LIBSUBCMD_OUTPUT): + $(Q)$(MKDIR) -p $@ + +$(LIBSUBCMD): fixdep $(LIBSUBCMD_OUTPUT) FORCE + $(Q)$(MAKE) -C $(LIBSUBCMD_DIR) O=$(LIBSUBCMD_OUTPUT) \ + DESTDIR=$(LIBSUBCMD_OUTPUT) prefix= subdir= \ + $(HOST_OVERRIDES) EXTRA_CFLAGS="$(OBJTOOL_CFLAGS)" \ + $@ + +$(LIBSUBCMD)-clean: + $(call QUIET_CLEAN, libsubcmd) + $(Q)$(RM) -r -- $(LIBSUBCMD_OUTPUT) + +clean: $(LIBSUBCMD)-clean + $(Q)find $(OUTPUT) \( -name '*.o' -o -name '\.*.cmd' -o -name '\.*.d' \) -type f -print | xargs $(RM) + $(Q)$(RM) $(OUTPUT)arch/x86/lib/cpu-feature-names.c $(OUTPUT)fixdep + $(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep + $(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.objtool + $(Q)$(RM) -r -- $(OUTPUT)feature + +mrproper: clean + $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL) + +FORCE: + +.PHONY: clean mrproper FORCE -- cgit v1.3.1