[PATCH RFC 3/4] stackleak: Split STACKLEAK_CFLAGS from GCC_PLUGINS_CFLAGS

Kees Cook
2025-05-02T19:01:32Z

In preparation for Clang stack depth tracking for stackleak, split the
stackleak-specific cflags out of GCC_PLUGINS_CFLAGS into
STACKLEAK_CFLAGS.

Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <x86@kernel.org>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: <sparclinux@vger.kernel.org>
Cc: <linux-kbuild@vger.kernel.org>
Cc: <linux-hardening@vger.kernel.org>
---
arch/arm/vdso/Makefile | 2 +-
arch/arm64/kernel/vdso/Makefile | 1 +
arch/sparc/vdso/Makefile | 3 ++-
arch/x86/entry/vdso/Makefile | 3 ++-
scripts/Makefile.gcc-plugins | 11 ++++++-----
5 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
index cb044bfd145d..92748e341b7d 100644
--- a/arch/arm/vdso/Makefile
+++ b/arch/arm/vdso/Makefile
@@ -26,7 +26,7 @@ CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
CFLAGS_REMOVE_vdso.o = -pg

# Force -O2 to avoid libgcc dependencies
-CFLAGS_REMOVE_vgettimeofday.o = -pg -Os $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS)
+CFLAGS_REMOVE_vgettimeofday.o = -pg -Os $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(STACKLEAK_CFLAGS)
ifeq ($(c-gettimeofday-y),)
CFLAGS_vgettimeofday.o = -O2
else
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 5e27e46aa496..fb17749b93cf 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -37,6 +37,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
# the CFLAGS to make possible to build the kernel with CONFIG_WERROR enabled.
CC_FLAGS_REMOVE_VDSO := $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
$(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \
+ $(STACKLEAK_CFLAGS) \
$(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
-Wmissing-prototypes -Wmissing-declarations

diff --git a/arch/sparc/vdso/Makefile b/arch/sparc/vdso/Makefile
index fdc4a8f5a49c..162a0235f41f 100644
--- a/arch/sparc/vdso/Makefile
+++ b/arch/sparc/vdso/Makefile
@@ -48,7 +48,7 @@ CFL := $(PROFILING) -mcmodel=medlow -fPIC -O2 -fasynchronous-unwind-tables -m64

SPARC_REG_CFLAGS = -ffixed-g4 -ffixed-g5 $(call cc-option,-fcall-used-g5) $(call cc-option,-fcall-used-g7)

-$(vobjs): KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
+$(vobjs): KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(STACKLEAK_CFLAGS) $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)

#
# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
@@ -80,6 +80,7 @@ KBUILD_CFLAGS_32 := $(filter-out -mcmodel=medlow,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out $(STACKLEAK_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 += -m32 -msoft-float -fpic
KBUILD_CFLAGS_32 += -fno-stack-protector
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 54d3e9774d62..cd5249b6ef84 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -62,7 +62,7 @@ ifneq ($(RETPOLINE_VDSO_CFLAGS),)
endif
endif

-$(vobjs): KBUILD_CFLAGS := $(filter-out $(PADDING_CFLAGS) $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
+$(vobjs): KBUILD_CFLAGS := $(filter-out $(PADDING_CFLAGS) $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(STACKLEAK_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
$(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO

#
@@ -124,6 +124,7 @@ KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out $(STACKLEAK_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32))
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index e3ed92e20d16..398b70e2d270 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -23,18 +23,19 @@ gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) \
+= -DSTRUCTLEAK_PLUGIN

gcc-plugin-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak_plugin.so
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+gcc-plugin-stackleak-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -DSTACKLEAK_PLUGIN
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+gcc-plugin-stackleak-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_STACKLEAK_TRACK_MIN_SIZE)
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+gcc-plugin-stackleak-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -fplugin-arg-stackleak_plugin-arch=$(SRCARCH)
-gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) \
+gcc-plugin-stackleak-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) \
+= -fplugin-arg-stackleak_plugin-verbose
ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+ STACKLEAK_CFLAGS = $(gcc-plugin-stackleak-cflags-y)
DISABLE_STACKLEAK += -fplugin-arg-stackleak_plugin-disable
endif
-export DISABLE_STACKLEAK
+export STACKLEAK_CFLAGS DISABLE_STACKLEAK

gcc-plugin-$(CONFIG_GCC_PLUGIN_ARM_SSP_PER_TASK) += arm_ssp_per_task_plugin.so
ifdef CONFIG_GCC_PLUGIN_ARM_SSP_PER_TASK
--
2.34.1