1# SPDX-License-Identifier: GPL-2.0 2ifneq ($(O),) 3ifeq ($(origin O), command line) 4 dummy := $(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),) 5 ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd) 6 OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/) 7 COMMAND_O := O=$(ABSOLUTE_O) 8ifeq ($(objtree),) 9 objtree := $(O) 10endif 11endif 12endif 13 14# check that the output directory actually exists 15ifneq ($(OUTPUT),) 16OUTDIR := $(shell cd $(OUTPUT) && pwd) 17$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist)) 18endif 19 20# 21# Include saner warnings here, which can catch bugs: 22# 23EXTRA_WARNINGS := -Wbad-function-cast 24EXTRA_WARNINGS += -Wdeclaration-after-statement 25EXTRA_WARNINGS += -Wformat-security 26EXTRA_WARNINGS += -Wformat-y2k 27EXTRA_WARNINGS += -Winit-self 28EXTRA_WARNINGS += -Wmissing-declarations 29EXTRA_WARNINGS += -Wmissing-prototypes 30EXTRA_WARNINGS += -Wnested-externs 31EXTRA_WARNINGS += -Wno-system-headers 32EXTRA_WARNINGS += -Wold-style-definition 33EXTRA_WARNINGS += -Wpacked 34EXTRA_WARNINGS += -Wredundant-decls 35EXTRA_WARNINGS += -Wstrict-prototypes 36EXTRA_WARNINGS += -Wswitch-default 37EXTRA_WARNINGS += -Wswitch-enum 38EXTRA_WARNINGS += -Wundef 39EXTRA_WARNINGS += -Wwrite-strings 40EXTRA_WARNINGS += -Wformat 41EXTRA_WARNINGS += -Wno-type-limits 42 43# Makefiles suck: This macro sets a default value of $(2) for the 44# variable named by $(1), unless the variable has been set by 45# environment or command line. This is necessary for CC and AR 46# because make sets default values, so the simpler ?= approach 47# won't work as expected. 48define allow-override 49 $(if $(or $(findstring environment,$(origin $(1))),\ 50 $(findstring command line,$(origin $(1)))),,\ 51 $(eval $(1) = $(2))) 52endef 53 54ifneq ($(LLVM),) 55ifneq ($(filter %/,$(LLVM)),) 56LLVM_PREFIX := $(LLVM) 57else ifneq ($(filter -%,$(LLVM)),) 58LLVM_SUFFIX := $(LLVM) 59endif 60 61$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX)) 62$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)) 63$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)) 64$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX)) 65$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)) 66else 67# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. 68$(call allow-override,CC,$(CROSS_COMPILE)gcc) 69$(call allow-override,AR,$(CROSS_COMPILE)ar) 70$(call allow-override,LD,$(CROSS_COMPILE)ld) 71$(call allow-override,CXX,$(CROSS_COMPILE)g++) 72$(call allow-override,STRIP,$(CROSS_COMPILE)strip) 73endif 74 75CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) 76 77ifneq ($(LLVM),) 78HOSTAR ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX) 79HOSTCC ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX) 80HOSTLD ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX) 81else 82HOSTAR ?= ar 83HOSTCC ?= gcc 84HOSTLD ?= ld 85endif 86 87# Some tools require Clang, LLC and/or LLVM utils 88CLANG ?= clang 89LLC ?= llc 90LLVM_CONFIG ?= llvm-config 91LLVM_OBJCOPY ?= llvm-objcopy 92LLVM_STRIP ?= llvm-strip 93 94ifeq ($(CC_NO_CLANG), 1) 95EXTRA_WARNINGS += -Wstrict-aliasing=3 96 97else ifneq ($(CROSS_COMPILE),) 98# Allow userspace to override CLANG_CROSS_FLAGS to specify their own 99# sysroots and flags or to avoid the GCC call in pure Clang builds. 100ifeq ($(CLANG_CROSS_FLAGS),) 101CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) 102GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null)) 103ifneq ($(GCC_TOOLCHAIN_DIR),) 104CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) 105CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot) 106CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..) 107endif # GCC_TOOLCHAIN_DIR 108endif # CLANG_CROSS_FLAGS 109CFLAGS += $(CLANG_CROSS_FLAGS) 110AFLAGS += $(CLANG_CROSS_FLAGS) 111endif # CROSS_COMPILE 112 113# Hack to avoid type-punned warnings on old systems such as RHEL5: 114# We should be changing CFLAGS and checking gcc version, but this 115# will do for now and keep the above -Wstrict-aliasing=3 in place 116# in newer systems. 117# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h 118# 119# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/ 120# and https://gcc.gnu.org/gcc-4.8/changes.html, 121# that takes into account Linus's comments (search for Wshadow) for the reasoning about 122# -Wshadow not being interesting before gcc 4.8. 123 124ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 125EXTRA_WARNINGS += -fno-strict-aliasing 126EXTRA_WARNINGS += -Wno-shadow 127else 128EXTRA_WARNINGS += -Wshadow 129endif 130 131ifneq ($(findstring $(MAKEFLAGS), w),w) 132PRINT_DIR = --no-print-directory 133else 134NO_SUBDIR = : 135endif 136 137ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),) 138 silent=1 139endif 140 141# 142# Define a callable command for descending to a new directory 143# 144# Call by doing: $(call descend,directory[,target]) 145# 146descend = \ 147 +mkdir -p $(OUTPUT)$(1) && \ 148 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 149 150QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir 151QUIET_SUBDIR1 = 152 153ifneq ($(silent),1) 154 ifneq ($(V),1) 155 QUIET_CC = @echo ' CC '$@; 156 QUIET_CC_FPIC = @echo ' CC FPIC '$@; 157 QUIET_CLANG = @echo ' CLANG '$@; 158 QUIET_AR = @echo ' AR '$@; 159 QUIET_LINK = @echo ' LINK '$@; 160 QUIET_MKDIR = @echo ' MKDIR '$@; 161 QUIET_GEN = @echo ' GEN '$@; 162 QUIET_SUBDIR0 = +@subdir= 163 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ 164 echo ' SUBDIR '$$subdir; \ 165 $(MAKE) $(PRINT_DIR) -C $$subdir 166 QUIET_FLEX = @echo ' FLEX '$@; 167 QUIET_BISON = @echo ' BISON '$@; 168 QUIET_GENSKEL = @echo ' GENSKEL '$@; 169 170 descend = \ 171 +@echo ' DESCEND '$(1); \ 172 mkdir -p $(OUTPUT)$(1) && \ 173 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 174 175 QUIET_CLEAN = @printf ' CLEAN %s\n' $1; 176 QUIET_INSTALL = @printf ' INSTALL %s\n' $1; 177 QUIET_UNINST = @printf ' UNINST %s\n' $1; 178 endif 179endif 180 181pound := \# 182