diff options
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 139 |
1 files changed, 135 insertions, 4 deletions
@@ -372,6 +372,7 @@ HOST_LOADLIBES := $(HOST_LFS_LIBS) # Make variables (CC, etc...) AS = $(CROSS_COMPILE)as LD = $(CROSS_COMPILE)ld +LDGOLD = $(CROSS_COMPILE)ld.gold CC = $(CROSS_COMPILE)gcc CPP = $(CC) -E AR = $(CROSS_COMPILE)ar @@ -480,7 +481,11 @@ endif ifeq ($(cc-name),clang) ifneq ($(CROSS_COMPILE),) -CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) +CLANG_TRIPLE ?= $(CROSS_COMPILE) +CLANG_FLAGS += --target=$(notdir $(CLANG_TRIPLE:%-=%)) +ifeq ($(shell $(srctree)/scripts/clang-android.sh $(CC) $(CLANG_FLAGS)), y) +$(error "Clang with Android --target detected. Did you specify CLANG_TRIPLE?") +endif GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR) GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) @@ -493,6 +498,10 @@ CLANG_FLAGS += -Werror=unknown-warning-option KBUILD_CFLAGS += $(CLANG_FLAGS) KBUILD_AFLAGS += $(CLANG_FLAGS) export CLANG_FLAGS +ifeq ($(ld-name),lld) +KBUILD_CFLAGS += -fuse-ld=lld +endif +KBUILD_CPPFLAGS += -Qunused-arguments endif RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register @@ -636,10 +645,28 @@ all: vmlinux KBUILD_CFLAGS += $(call cc-option,-fno-PIE) KBUILD_AFLAGS += $(call cc-option,-fno-PIE) -CFLAGS_GCOV := -fprofile-arcs -ftest-coverage -fno-tree-loop-im $(call cc-disable-warning,maybe-uninitialized,) +CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \ + $(call cc-option,-fno-tree-loop-im) \ + $(call cc-disable-warning,maybe-uninitialized,) CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) export CFLAGS_GCOV CFLAGS_KCOV +# Make toolchain changes before including arch/$(SRCARCH)/Makefile to ensure +# ar/cc/ld-* macros return correct values. +ifdef CONFIG_LTO_CLANG +ifneq ($(ld-name),lld) +# use GNU gold with LLVMgold for LTO linking, and LD for vmlinux_link +LDFINAL_vmlinux := $(LD) +LD := $(LDGOLD) +LDFLAGS += -plugin LLVMgold.so +endif +# use llvm-ar for building symbol tables from IR files, and llvm-dis instead +# of objdump for processing symbol versions and exports +LLVM_AR := llvm-ar +LLVM_NM := llvm-nm +export LLVM_AR LLVM_NM +endif + # The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default # values of the respective KBUILD_* variables ARCH_CPPFLAGS := @@ -716,9 +743,9 @@ endif KBUILD_CFLAGS += $(stackp-flag) ifeq ($(cc-name),clang) -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) KBUILD_CFLAGS += $(call cc-disable-warning, gnu) +KBUILD_CFLAGS += $(call cc-disable-warning, duplicate-decl-specifier) # Quiet clang warning: comparison of unsigned expression < 0 is always false KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the @@ -733,6 +760,10 @@ else KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) endif +ifeq ($(ld-name),lld) +LDFLAGS += -O2 +endif + KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable) ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls @@ -747,6 +778,11 @@ KBUILD_CFLAGS += -fomit-frame-pointer endif endif +# Initialize all stack variables with a pattern, if desired. +ifdef CONFIG_INIT_STACK_ALL +KBUILD_CFLAGS += -ftrivial-auto-var-init=pattern +endif + KBUILD_CFLAGS += $(call cc-option, -fno-var-tracking-assignments) ifdef CONFIG_DEBUG_INFO @@ -794,6 +830,73 @@ KBUILD_CFLAGS += $(call cc-option,-ffunction-sections,) KBUILD_CFLAGS += $(call cc-option,-fdata-sections,) endif +ifdef CONFIG_LTO_CLANG +ifdef CONFIG_THINLTO +lto-clang-flags := -flto=thin +LDFLAGS += --thinlto-cache-dir=.thinlto-cache +else +lto-clang-flags := -flto +endif +lto-clang-flags += -fvisibility=default $(call cc-option, -fsplit-lto-unit) + +# Limit inlining across translation units to reduce binary size +LD_FLAGS_LTO_CLANG := -mllvm -import-instr-limit=5 + +KBUILD_LDFLAGS += $(LD_FLAGS_LTO_CLANG) +KBUILD_LDFLAGS_MODULE += $(LD_FLAGS_LTO_CLANG) + +KBUILD_LDS_MODULE += $(srctree)/scripts/module-lto.lds + +# allow disabling only clang LTO where needed +DISABLE_LTO_CLANG := -fno-lto +export DISABLE_LTO_CLANG +endif + +ifdef CONFIG_LTO +lto-flags := $(lto-clang-flags) +KBUILD_CFLAGS += $(lto-flags) + +DISABLE_LTO := $(DISABLE_LTO_CLANG) +export DISABLE_LTO + +# LDFINAL_vmlinux and LDFLAGS_FINAL_vmlinux can be set to override +# the linker and flags for vmlinux_link. +export LDFINAL_vmlinux LDFLAGS_FINAL_vmlinux +endif + +ifdef CONFIG_CFI_CLANG +cfi-clang-flags += -fsanitize=cfi -fno-sanitize-cfi-canonical-jump-tables +DISABLE_CFI_CLANG := -fno-sanitize=cfi +ifdef CONFIG_MODULES +cfi-clang-flags += -fsanitize-cfi-cross-dso +DISABLE_CFI_CLANG += -fno-sanitize-cfi-cross-dso +endif +ifdef CONFIG_CFI_PERMISSIVE +cfi-clang-flags += -fsanitize-recover=cfi -fno-sanitize-trap=cfi +endif + +# also disable CFI when LTO is disabled +DISABLE_LTO_CLANG += $(DISABLE_CFI_CLANG) +# allow disabling only clang CFI where needed +export DISABLE_CFI_CLANG +endif + +ifdef CONFIG_CFI +# cfi-flags are re-tested in prepare-compiler-check +cfi-flags := $(cfi-clang-flags) +KBUILD_CFLAGS += $(cfi-flags) + +DISABLE_CFI := $(DISABLE_CFI_CLANG) +DISABLE_LTO += $(DISABLE_CFI) +export DISABLE_CFI +endif + +ifdef CONFIG_SHADOW_CALL_STACK +CC_FLAGS_SCS := -fsanitize=shadow-call-stack +KBUILD_CFLAGS += $(CC_FLAGS_SCS) +export CC_FLAGS_SCS +endif + # arch Makefile may override CC so keep this after arch Makefile is included NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) CHECKFLAGS += $(NOSTDINC_FLAGS) @@ -876,6 +979,10 @@ ifeq ($(CONFIG_STRIP_ASM_SYMS),y) LDFLAGS_vmlinux += $(call ld-option, -X,) endif +ifeq ($(CONFIG_RELR),y) +LDFLAGS_vmlinux += --pack-dyn-relocs=relr +endif + # Default kernel image to build when no specific target is given. # KBUILD_IMAGE may be overruled on the command line or # set in the environment @@ -1128,6 +1235,24 @@ endif # CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!") PHONY += prepare-compiler-check prepare-compiler-check: FORCE +# Make sure we're using a supported toolchain with LTO_CLANG +ifdef CONFIG_LTO_CLANG + ifneq ($(call clang-ifversion, -ge, 0500, y), y) + @echo Cannot use CONFIG_LTO_CLANG: requires clang 5.0 or later >&2 && exit 1 + endif + ifneq ($(ld-name),lld) + ifneq ($(call gold-ifversion, -ge, 112000000, y), y) + @echo Cannot use CONFIG_LTO_CLANG: requires GNU gold 1.12 or later >&2 && exit 1 + endif + endif +endif +# Make sure compiler supports LTO flags +ifdef lto-flags + ifeq ($(call cc-option, $(lto-flags)),) + @echo Cannot use CONFIG_LTO: $(lto-flags) not supported by compiler \ + >&2 && exit 1 + endif +endif # Make sure compiler supports requested stack protector flag. ifdef stackp-name ifeq ($(call cc-option, $(stackp-flag)),) @@ -1142,6 +1267,11 @@ ifdef stackp-check $(stackp-flag) available but compiler is broken >&2 && exit 1 endif endif +ifdef cfi-flags + ifeq ($(call cc-option, $(cfi-flags)),) + @echo Cannot use CONFIG_CFI: $(cfi-flags) not supported by compiler >&2 && exit 1 + endif +endif @: # Generate some files @@ -1599,7 +1729,8 @@ clean: $(clean-dirs) -o -name modules.builtin -o -name '.tmp_*.o.*' \ -o -name '*.c.[012]*.*' \ -o -name '*.ll' \ - -o -name '*.gcno' \) -type f -print | xargs rm -f + -o -name '*.gcno' \ + -o -name '*.*.symversions' \) -type f -print | xargs rm -f # Generate tags for editors # --------------------------------------------------------------------------- |