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39218ff4c6
linux/Makefile
Kees Cook 39218ff4c6 stack: Optionally randomize kernel stack offset each syscall 
This provides the ability for architectures to enable kernel stack base
address offset randomization. This feature is controlled by the boot
param "randomize_kstack_offset=on/off", with its default value set by
CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT.

This feature is based on the original idea from the last public release
of PaX's RANDKSTACK feature: https://pax.grsecurity.net/docs/randkstack.txt
All the credit for the original idea goes to the PaX team. Note that
the design and implementation of this upstream randomize_kstack_offset
feature differs greatly from the RANDKSTACK feature (see below).

Reasoning for the feature:

This feature aims to make harder the various stack-based attacks that
rely on deterministic stack structure. We have had many such attacks in
past (just to name few):

https://jon.oberheide.org/files/infiltrate12-thestackisback.pdf
https://jon.oberheide.org/files/stackjacking-infiltrate11.pdf
https://googleprojectzero.blogspot.com/2016/06/exploiting-recursion-in-linux-kernel_20.html

As Linux kernel stack protections have been constantly improving
(vmap-based stack allocation with guard pages, removal of thread_info,
STACKLEAK), attackers have had to find new ways for their exploits
to work. They have done so, continuing to rely on the kernel's stack
determinism, in situations where VMAP_STACK and THREAD_INFO_IN_TASK_STRUCT
were not relevant. For example, the following recent attacks would have
been hampered if the stack offset was non-deterministic between syscalls:

https://repositorio-aberto.up.pt/bitstream/10216/125357/2/374717.pdf
(page 70: targeting the pt_regs copy with linear stack overflow)

https://a13xp0p0v.github.io/2020/02/15/CVE-2019-18683.html
(leaked stack address from one syscall as a target during next syscall)

The main idea is that since the stack offset is randomized on each system
call, it is harder for an attack to reliably land in any particular place
on the thread stack, even with address exposures, as the stack base will
change on the next syscall. Also, since randomization is performed after
placing pt_regs, the ptrace-based approach[1] to discover the randomized
offset during a long-running syscall should not be possible.

Design description:

During most of the kernel's execution, it runs on the "thread stack",
which is pretty deterministic in its structure: it is fixed in size,
and on every entry from userspace to kernel on a syscall the thread
stack starts construction from an address fetched from the per-cpu
cpu_current_top_of_stack variable. The first element to be pushed to the
thread stack is the pt_regs struct that stores all required CPU registers
and syscall parameters. Finally the specific syscall function is called,
with the stack being used as the kernel executes the resulting request.

The goal of randomize_kstack_offset feature is to add a random offset
after the pt_regs has been pushed to the stack and before the rest of the
thread stack is used during the syscall processing, and to change it every
time a process issues a syscall. The source of randomness is currently
architecture-defined (but x86 is using the low byte of rdtsc()). Future
improvements for different entropy sources is possible, but out of scope
for this patch. Further more, to add more unpredictability, new offsets
are chosen at the end of syscalls (the timing of which should be less
easy to measure from userspace than at syscall entry time), and stored
in a per-CPU variable, so that the life of the value does not stay
explicitly tied to a single task.

As suggested by Andy Lutomirski, the offset is added using alloca()
and an empty asm() statement with an output constraint, since it avoids
changes to assembly syscall entry code, to the unwinder, and provides
correct stack alignment as defined by the compiler.

In order to make this available by default with zero performance impact
for those that don't want it, it is boot-time selectable with static
branches. This way, if the overhead is not wanted, it can just be
left turned off with no performance impact.

The generated assembly for x86_64 with GCC looks like this:

...
ffffffff81003977: 65 8b 05 02 ea 00 7f  mov %gs:0x7f00ea02(%rip),%eax
					    # 12380 <kstack_offset>
ffffffff8100397e: 25 ff 03 00 00        and $0x3ff,%eax
ffffffff81003983: 48 83 c0 0f           add $0xf,%rax
ffffffff81003987: 25 f8 07 00 00        and $0x7f8,%eax
ffffffff8100398c: 48 29 c4              sub %rax,%rsp
ffffffff8100398f: 48 8d 44 24 0f        lea 0xf(%rsp),%rax
ffffffff81003994: 48 83 e0 f0           and $0xfffffffffffffff0,%rax
...

As a result of the above stack alignment, this patch introduces about
5 bits of randomness after pt_regs is spilled to the thread stack on
x86_64, and 6 bits on x86_32 (since its has 1 fewer bit required for
stack alignment). The amount of entropy could be adjusted based on how
much of the stack space we wish to trade for security.

My measure of syscall performance overhead (on x86_64):

lmbench: /usr/lib/lmbench/bin/x86_64-linux-gnu/lat_syscall -N 10000 null
    randomize_kstack_offset=y	Simple syscall: 0.7082 microseconds
    randomize_kstack_offset=n	Simple syscall: 0.7016 microseconds

So, roughly 0.9% overhead growth for a no-op syscall, which is very
manageable. And for people that don't want this, it's off by default.

There are two gotchas with using the alloca() trick. First,
compilers that have Stack Clash protection (-fstack-clash-protection)
enabled by default (e.g. Ubuntu[3]) add pagesize stack probes to
any dynamic stack allocations. While the randomization offset is
always less than a page, the resulting assembly would still contain
(unreachable!) probing routines, bloating the resulting assembly. To
avoid this, -fno-stack-clash-protection is unconditionally added to
the kernel Makefile since this is the only dynamic stack allocation in
the kernel (now that VLAs have been removed) and it is provably safe
from Stack Clash style attacks.

The second gotcha with alloca() is a negative interaction with
-fstack-protector*, in that it sees the alloca() as an array allocation,
which triggers the unconditional addition of the stack canary function
pre/post-amble which slows down syscalls regardless of the static
branch. In order to avoid adding this unneeded check and its associated
performance impact, architectures need to carefully remove uses of
-fstack-protector-strong (or -fstack-protector) in the compilation units
that use the add_random_kstack() macro and to audit the resulting stack
mitigation coverage (to make sure no desired coverage disappears). No
change is visible for this on x86 because the stack protector is already
unconditionally disabled for the compilation unit, but the change is
required on arm64. There is, unfortunately, no attribute that can be
used to disable stack protector for specific functions.

Comparison to PaX RANDKSTACK feature:

The RANDKSTACK feature randomizes the location of the stack start
(cpu_current_top_of_stack), i.e. including the location of pt_regs
structure itself on the stack. Initially this patch followed the same
approach, but during the recent discussions[2], it has been determined
to be of a little value since, if ptrace functionality is available for
an attacker, they can use PTRACE_PEEKUSR/PTRACE_POKEUSR to read/write
different offsets in the pt_regs struct, observe the cache behavior of
the pt_regs accesses, and figure out the random stack offset. Another
difference is that the random offset is stored in a per-cpu variable,
rather than having it be per-thread. As a result, these implementations
differ a fair bit in their implementation details and results, though
obviously the intent is similar.

[1] https://lore.kernel.org/kernel-hardening/2236FBA76BA1254E88B949DDB74E612BA4BC57C1@IRSMSX102.ger.corp.intel.com/
[2] https://lore.kernel.org/kernel-hardening/20190329081358.30497-1-elena.reshetova@intel.com/
[3] https://lists.ubuntu.com/archives/ubuntu-devel/2019-June/040741.html

Co-developed-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210401232347.2791257-4-keescook@chromium.org
2021-04-08 14:05:19 +02:00

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Makefile
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# SPDX-License-Identifier: GPL-2.0
VERSION = 5
PATCHLEVEL = 12
SUBLEVEL = 0
EXTRAVERSION = -rc6
NAME = Frozen Wasteland
# *DOCUMENTATION*
# To see a list of typical targets execute "make help"
# More info can be located in ./README
# Comments in this file are targeted only to the developer, do not
# expect to learn how to build the kernel reading this file.
$(if $(filter __%, $(MAKECMDGOALS)), \
$(error targets prefixed with '__' are only for internal use))
# That's our default target when none is given on the command line
PHONY := __all
__all:
# We are using a recursive build, so we need to do a little thinking
# to get the ordering right.
#
# Most importantly: sub-Makefiles should only ever modify files in
# their own directory. If in some directory we have a dependency on
# a file in another dir (which doesn't happen often, but it's often
# unavoidable when linking the built-in.a targets which finally
# turn into vmlinux), we will call a sub make in that other dir, and
# after that we are sure that everything which is in that other dir
# is now up to date.
#
# The only cases where we need to modify files which have global
# effects are thus separated out and done before the recursive
# descending is started. They are now explicitly listed as the
# prepare rule.
ifneq ($(sub_make_done),1)
# Do not use make's built-in rules and variables
# (this increases performance and avoids hard-to-debug behaviour)
MAKEFLAGS += -rR
# Avoid funny character set dependencies
unexport LC_ALL
LC_COLLATE=C
LC_NUMERIC=C
export LC_COLLATE LC_NUMERIC
# Avoid interference with shell env settings
unexport GREP_OPTIONS
# Beautify output
# ---------------------------------------------------------------------------
#
# Normally, we echo the whole command before executing it. By making
# that echo $($(quiet)$(cmd)), we now have the possibility to set
# $(quiet) to choose other forms of output instead, e.g.
#
# quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
# cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
#
# If $(quiet) is empty, the whole command will be printed.
# If it is set to "quiet_", only the short version will be printed.
# If it is set to "silent_", nothing will be printed at all, since
# the variable $(silent_cmd_cc_o_c) doesn't exist.
#
# A simple variant is to prefix commands with $(Q) - that's useful
# for commands that shall be hidden in non-verbose mode.
#
# $(Q)ln $@ :<
#
# If KBUILD_VERBOSE equals 0 then the above command will be hidden.
# If KBUILD_VERBOSE equals 1 then the above command is displayed.
# If KBUILD_VERBOSE equals 2 then give the reason why each target is rebuilt.
#
# To put more focus on warnings, be less verbose as default
# Use 'make V=1' to see the full commands
ifeq ("$(origin V)", "command line")
KBUILD_VERBOSE = $(V)
endif
ifndef KBUILD_VERBOSE
KBUILD_VERBOSE = 0
endif
ifeq ($(KBUILD_VERBOSE),1)
quiet =
Q =
else
quiet=quiet_
Q = @
endif
# If the user is running make -s (silent mode), suppress echoing of
# commands
ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
quiet=silent_
KBUILD_VERBOSE = 0
endif
export quiet Q KBUILD_VERBOSE
# Call a source code checker (by default, "sparse") as part of the
# C compilation.
#
# Use 'make C=1' to enable checking of only re-compiled files.
# Use 'make C=2' to enable checking of *all* source files, regardless
# of whether they are re-compiled or not.
#
# See the file "Documentation/dev-tools/sparse.rst" for more details,
# including where to get the "sparse" utility.
ifeq ("$(origin C)", "command line")
KBUILD_CHECKSRC = $(C)
endif
ifndef KBUILD_CHECKSRC
KBUILD_CHECKSRC = 0
endif
export KBUILD_CHECKSRC
# Use make M=dir or set the environment variable KBUILD_EXTMOD to specify the
# directory of external module to build. Setting M= takes precedence.
ifeq ("$(origin M)", "command line")
KBUILD_EXTMOD := $(M)
endif
$(if $(word 2, $(KBUILD_EXTMOD)), \
$(error building multiple external modules is not supported))
export KBUILD_EXTMOD
# Kbuild will save output files in the current working directory.
# This does not need to match to the root of the kernel source tree.
#
# For example, you can do this:
#
# cd /dir/to/store/output/files; make -f /dir/to/kernel/source/Makefile
#
# If you want to save output files in a different location, there are
# two syntaxes to specify it.
#
# 1) O=
# Use "make O=dir/to/store/output/files/"
#
# 2) Set KBUILD_OUTPUT
# Set the environment variable KBUILD_OUTPUT to point to the output directory.
# export KBUILD_OUTPUT=dir/to/store/output/files/; make
#
# The O= assignment takes precedence over the KBUILD_OUTPUT environment
# variable.
# Do we want to change the working directory?
ifeq ("$(origin O)", "command line")
KBUILD_OUTPUT := $(O)
endif
ifneq ($(KBUILD_OUTPUT),)
# Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
# expand a shell special character '~'. We use a somewhat tedious way here.
abs_objtree := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
$(if $(abs_objtree),, \
$(error failed to create output directory "$(KBUILD_OUTPUT)"))
# $(realpath ...) resolves symlinks
abs_objtree := $(realpath $(abs_objtree))
else
abs_objtree := $(CURDIR)
endif # ifneq ($(KBUILD_OUTPUT),)
ifeq ($(abs_objtree),$(CURDIR))
# Suppress "Entering directory ..." unless we are changing the work directory.
MAKEFLAGS += --no-print-directory
else
need-sub-make := 1
endif
this-makefile := $(lastword $(MAKEFILE_LIST))
abs_srctree := $(realpath $(dir $(this-makefile)))
ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
$(error source directory cannot contain spaces or colons)
endif
ifneq ($(abs_srctree),$(abs_objtree))
# Look for make include files relative to root of kernel src
#
# This does not become effective immediately because MAKEFLAGS is re-parsed
# once after the Makefile is read. We need to invoke sub-make.
MAKEFLAGS += --include-dir=$(abs_srctree)
need-sub-make := 1
endif
ifneq ($(filter 3.%,$(MAKE_VERSION)),)
# 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
# We need to invoke sub-make to avoid implicit rules in the top Makefile.
need-sub-make := 1
# Cancel implicit rules for this Makefile.
$(this-makefile): ;
endif
export abs_srctree abs_objtree
export sub_make_done := 1
ifeq ($(need-sub-make),1)
PHONY += $(MAKECMDGOALS) __sub-make
$(filter-out $(this-makefile), $(MAKECMDGOALS)) __all: __sub-make
@:
# Invoke a second make in the output directory, passing relevant variables
__sub-make:
$(Q)$(MAKE) -C $(abs_objtree) -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
endif # need-sub-make
endif # sub_make_done
# We process the rest of the Makefile if this is the final invocation of make
ifeq ($(need-sub-make),)
# Do not print "Entering directory ...",
# but we want to display it when entering to the output directory
# so that IDEs/editors are able to understand relative filenames.
MAKEFLAGS += --no-print-directory
ifeq ($(abs_srctree),$(abs_objtree))
# building in the source tree
srctree := .
building_out_of_srctree :=
else
ifeq ($(abs_srctree)/,$(dir $(abs_objtree)))
# building in a subdirectory of the source tree
srctree := ..
else
srctree := $(abs_srctree)
endif
building_out_of_srctree := 1
endif
ifneq ($(KBUILD_ABS_SRCTREE),)
srctree := $(abs_srctree)
endif
objtree := .
VPATH := $(srctree)
export building_out_of_srctree srctree objtree VPATH
# To make sure we do not include .config for any of the *config targets
# catch them early, and hand them over to scripts/kconfig/Makefile
# It is allowed to specify more targets when calling make, including
# mixing *config targets and build targets.
# For example 'make oldconfig all'.
# Detect when mixed targets is specified, and make a second invocation
# of make so .config is not included in this case either (for *config).
version_h := include/generated/uapi/linux/version.h
clean-targets := %clean mrproper cleandocs
no-dot-config-targets := $(clean-targets) \
cscope gtags TAGS tags help% %docs check% coccicheck \
$(version_h) headers headers_% archheaders archscripts \
%asm-generic kernelversion %src-pkg dt_binding_check \
outputmakefile
no-sync-config-targets := $(no-dot-config-targets) %install kernelrelease \
image_name
single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
config-build :=
mixed-build :=
need-config := 1
may-sync-config := 1
single-build :=
ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
need-config :=
endif
endif
ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),)
ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
may-sync-config :=
endif
endif
ifneq ($(KBUILD_EXTMOD),)
may-sync-config :=
endif
ifeq ($(KBUILD_EXTMOD),)
ifneq ($(filter %config,$(MAKECMDGOALS)),)
config-build := 1
ifneq ($(words $(MAKECMDGOALS)),1)
mixed-build := 1
endif
endif
endif
# We cannot build single targets and the others at the same time
ifneq ($(filter $(single-targets), $(MAKECMDGOALS)),)
single-build := 1
ifneq ($(filter-out $(single-targets), $(MAKECMDGOALS)),)
mixed-build := 1
endif
endif
# For "make -j clean all", "make -j mrproper defconfig all", etc.
ifneq ($(filter $(clean-targets),$(MAKECMDGOALS)),)
ifneq ($(filter-out $(clean-targets),$(MAKECMDGOALS)),)
mixed-build := 1
endif
endif
# install and modules_install need also be processed one by one
ifneq ($(filter install,$(MAKECMDGOALS)),)
ifneq ($(filter modules_install,$(MAKECMDGOALS)),)
mixed-build := 1
endif
endif
ifdef mixed-build
# ===========================================================================
# We're called with mixed targets (*config and build targets).
# Handle them one by one.
PHONY += $(MAKECMDGOALS) __build_one_by_one
$(MAKECMDGOALS): __build_one_by_one
@:
__build_one_by_one:
$(Q)set -e; \
for i in $(MAKECMDGOALS); do \
$(MAKE) -f $(srctree)/Makefile $$i; \
done
else # !mixed-build
include scripts/Kbuild.include
# Read KERNELRELEASE from include/config/kernel.release (if it exists)
KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
include scripts/subarch.include
# Cross compiling and selecting different set of gcc/bin-utils
# ---------------------------------------------------------------------------
#
# When performing cross compilation for other architectures ARCH shall be set
# to the target architecture. (See arch/* for the possibilities).
# ARCH can be set during invocation of make:
# make ARCH=ia64
# Another way is to have ARCH set in the environment.
# The default ARCH is the host where make is executed.
# CROSS_COMPILE specify the prefix used for all executables used
# during compilation. Only gcc and related bin-utils executables
# are prefixed with $(CROSS_COMPILE).
# CROSS_COMPILE can be set on the command line
# make CROSS_COMPILE=ia64-linux-
# Alternatively CROSS_COMPILE can be set in the environment.
# Default value for CROSS_COMPILE is not to prefix executables
# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
ARCH ?= $(SUBARCH)
# Architecture as present in compile.h
UTS_MACHINE := $(ARCH)
SRCARCH := $(ARCH)
# Additional ARCH settings for x86
ifeq ($(ARCH),i386)
SRCARCH := x86
endif
ifeq ($(ARCH),x86_64)
SRCARCH := x86
endif
# Additional ARCH settings for sparc
ifeq ($(ARCH),sparc32)
SRCARCH := sparc
endif
ifeq ($(ARCH),sparc64)
SRCARCH := sparc
endif
# Additional ARCH settings for sh
ifeq ($(ARCH),sh64)
SRCARCH := sh
endif
KCONFIG_CONFIG ?= .config
export KCONFIG_CONFIG
# Default file for 'make defconfig'. This may be overridden by arch-Makefile.
export KBUILD_DEFCONFIG := defconfig
# SHELL used by kbuild
CONFIG_SHELL := sh
HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null)
HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null)
HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)
ifneq ($(LLVM),)
HOSTCC = clang
HOSTCXX = clang++
else
HOSTCC = gcc
HOSTCXX = g++
endif
export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
-O2 -fomit-frame-pointer -std=gnu89
export KBUILD_USERLDFLAGS :=
KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS)
KBUILD_HOSTLDFLAGS := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
# Make variables (CC, etc...)
CPP = $(CC) -E
ifneq ($(LLVM),)
CC = clang
LD = ld.lld
AR = llvm-ar
NM = llvm-nm
OBJCOPY = llvm-objcopy
OBJDUMP = llvm-objdump
READELF = llvm-readelf
STRIP = llvm-strip
else
CC = $(CROSS_COMPILE)gcc
LD = $(CROSS_COMPILE)ld
AR = $(CROSS_COMPILE)ar
NM = $(CROSS_COMPILE)nm
OBJCOPY = $(CROSS_COMPILE)objcopy
OBJDUMP = $(CROSS_COMPILE)objdump
READELF = $(CROSS_COMPILE)readelf
STRIP = $(CROSS_COMPILE)strip
endif
PAHOLE = pahole
RESOLVE_BTFIDS = $(objtree)/tools/bpf/resolve_btfids/resolve_btfids
LEX = flex
YACC = bison
AWK = awk
INSTALLKERNEL := installkernel
DEPMOD = depmod
PERL = perl
PYTHON3 = python3
CHECK = sparse
BASH = bash
KGZIP = gzip
KBZIP2 = bzip2
KLZOP = lzop
LZMA = lzma
LZ4 = lz4c
XZ = xz
ZSTD = zstd
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
-Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
NOSTDINC_FLAGS :=
CFLAGS_MODULE =
AFLAGS_MODULE =
LDFLAGS_MODULE =
CFLAGS_KERNEL =
AFLAGS_KERNEL =
LDFLAGS_vmlinux =
# Use USERINCLUDE when you must reference the UAPI directories only.
USERINCLUDE := \
-I$(srctree)/arch/$(SRCARCH)/include/uapi \
-I$(objtree)/arch/$(SRCARCH)/include/generated/uapi \
-I$(srctree)/include/uapi \
-I$(objtree)/include/generated/uapi \
-include $(srctree)/include/linux/compiler-version.h \
-include $(srctree)/include/linux/kconfig.h
# Use LINUXINCLUDE when you must reference the include/ directory.
# Needed to be compatible with the O= option
LINUXINCLUDE := \
-I$(srctree)/arch/$(SRCARCH)/include \
-I$(objtree)/arch/$(SRCARCH)/include/generated \
$(if $(building_out_of_srctree),-I$(srctree)/include) \
-I$(objtree)/include \
$(USERINCLUDE)
KBUILD_AFLAGS := -D__ASSEMBLY__ -fno-PIE
KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
-fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
-Werror=implicit-function-declaration -Werror=implicit-int \
-Werror=return-type -Wno-format-security \
-std=gnu89
KBUILD_CPPFLAGS := -D__KERNEL__
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
KBUILD_AFLAGS_MODULE := -DMODULE
KBUILD_CFLAGS_MODULE := -DMODULE
KBUILD_LDFLAGS_MODULE :=
KBUILD_LDFLAGS :=
CLANG_FLAGS :=
export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC
export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD
export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
# Files to ignore in find ... statements
export RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o \
-name CVS -o -name .pc -o -name .hg -o -name .git \) \
-prune -o
export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
--exclude CVS --exclude .pc --exclude .hg --exclude .git
# ===========================================================================
# Rules shared between *config targets and build targets
# Basic helpers built in scripts/basic/
PHONY += scripts_basic
scripts_basic:
$(Q)$(MAKE) $(build)=scripts/basic
$(Q)rm -f .tmp_quiet_recordmcount
PHONY += outputmakefile
# Before starting out-of-tree build, make sure the source tree is clean.
# outputmakefile generates a Makefile in the output directory, if using a
# separate output directory. This allows convenient use of make in the
# output directory.
# At the same time when output Makefile generated, generate .gitignore to
# ignore whole output directory
outputmakefile:
ifdef building_out_of_srctree
$(Q)if [ -f $(srctree)/.config -o \
-d $(srctree)/include/config -o \
-d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
echo >&2 "***"; \
echo >&2 "*** The source tree is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'"; \
echo >&2 "*** in $(abs_srctree)";\
echo >&2 "***"; \
false; \
fi
$(Q)ln -fsn $(srctree) source
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
$(Q)test -e .gitignore || \
{ echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
endif
# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
# CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
# and from include/config/auto.conf.cmd to detect the compiler upgrade.
CC_VERSION_TEXT = $(shell $(CC) --version 2>/dev/null | head -n 1 | sed 's/\#//g')
ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)
ifneq ($(CROSS_COMPILE),)
CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
endif
ifneq ($(GCC_TOOLCHAIN),)
CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN)
endif
ifneq ($(LLVM_IAS),1)
CLANG_FLAGS += -no-integrated-as
endif
CLANG_FLAGS += -Werror=unknown-warning-option
KBUILD_CFLAGS += $(CLANG_FLAGS)
KBUILD_AFLAGS += $(CLANG_FLAGS)
export CLANG_FLAGS
endif
ifdef config-build
# ===========================================================================
# *config targets only - make sure prerequisites are updated, and descend
# in scripts/kconfig to make the *config target
# Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
# KBUILD_DEFCONFIG may point out an alternative default configuration
# used for 'make defconfig'
include arch/$(SRCARCH)/Makefile
export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT
config: outputmakefile scripts_basic FORCE
$(Q)$(MAKE) $(build)=scripts/kconfig $@
%config: outputmakefile scripts_basic FORCE
$(Q)$(MAKE) $(build)=scripts/kconfig $@
else #!config-build
# ===========================================================================
# Build targets only - this includes vmlinux, arch specific targets, clean
# targets and others. In general all targets except *config targets.
# If building an external module we do not care about the all: rule
# but instead __all depend on modules
PHONY += all
ifeq ($(KBUILD_EXTMOD),)
__all: all
else
__all: modules
endif
# Decide whether to build built-in, modular, or both.
# Normally, just do built-in.
KBUILD_MODULES :=
KBUILD_BUILTIN := 1
# If we have only "make modules", don't compile built-in objects.
ifeq ($(MAKECMDGOALS),modules)
KBUILD_BUILTIN :=
endif
# If we have "make <whatever> modules", compile modules
# in addition to whatever we do anyway.
# Just "make" or "make all" shall build modules as well
ifneq ($(filter all modules nsdeps %compile_commands.json clang-%,$(MAKECMDGOALS)),)
KBUILD_MODULES := 1
endif
ifeq ($(MAKECMDGOALS),)
KBUILD_MODULES := 1
endif
export KBUILD_MODULES KBUILD_BUILTIN
ifdef need-config
include include/config/auto.conf
endif
ifeq ($(KBUILD_EXTMOD),)
# Objects we will link into vmlinux / subdirs we need to visit
core-y := init/ usr/
drivers-y := drivers/ sound/
drivers-$(CONFIG_SAMPLES) += samples/
drivers-$(CONFIG_NET) += net/
drivers-y += virt/
libs-y := lib/
endif # KBUILD_EXTMOD
# The all: target is the default when no target is given on the
# command line.
# This allow a user to issue only 'make' to build a kernel including modules
# Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux
CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
$(call cc-option,-fno-tree-loop-im) \
$(call cc-disable-warning,maybe-uninitialized,)
export CFLAGS_GCOV
# The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
ifdef CONFIG_FUNCTION_TRACER
CC_FLAGS_FTRACE := -pg
endif
RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register
RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
export RETPOLINE_CFLAGS
export RETPOLINE_VDSO_CFLAGS
include arch/$(SRCARCH)/Makefile
ifdef need-config
ifdef may-sync-config
# Read in dependencies to all Kconfig* files, make sure to run syncconfig if
# changes are detected. This should be included after arch/$(SRCARCH)/Makefile
# because some architectures define CROSS_COMPILE there.
include include/config/auto.conf.cmd
$(KCONFIG_CONFIG):
@echo >&2 '***'
@echo >&2 '*** Configuration file "$@" not found!'
@echo >&2 '***'
@echo >&2 '*** Please run some configurator (e.g. "make oldconfig" or'
@echo >&2 '*** "make menuconfig" or "make xconfig").'
@echo >&2 '***'
@/bin/false
# The actual configuration files used during the build are stored in
# include/generated/ and include/config/. Update them if .config is newer than
# include/config/auto.conf (which mirrors .config).
#
# This exploits the 'multi-target pattern rule' trick.
# The syncconfig should be executed only once to make all the targets.
# (Note: use the grouped target '&:' when we bump to GNU Make 4.3)
quiet_cmd_syncconfig = SYNC $@
cmd_syncconfig = $(MAKE) -f $(srctree)/Makefile syncconfig
%/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h: $(KCONFIG_CONFIG)
+$(call cmd,syncconfig)
else # !may-sync-config
# External modules and some install targets need include/generated/autoconf.h
# and include/config/auto.conf but do not care if they are up-to-date.
# Use auto.conf to trigger the test
PHONY += include/config/auto.conf
include/config/auto.conf:
$(Q)test -e include/generated/autoconf.h -a -e $@ || ( \
echo >&2; \
echo >&2 " ERROR: Kernel configuration is invalid."; \
echo >&2 " include/generated/autoconf.h or $@ are missing.";\
echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \
echo >&2 ; \
/bin/false)
endif # may-sync-config
endif # need-config
KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
KBUILD_CFLAGS += -O2
else ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
KBUILD_CFLAGS += -O3
else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS += -Os
endif
# Tell gcc to never replace conditional load with a non-conditional one
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races)
ifdef CONFIG_READABLE_ASM
# Disable optimizations that make assembler listings hard to read.
# reorder blocks reorders the control in the function
# ipa clone creates specialized cloned functions
# partial inlining inlines only parts of functions
KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \
$(call cc-option,-fno-ipa-cp-clone,) \
$(call cc-option,-fno-partial-inlining)
endif
ifneq ($(CONFIG_FRAME_WARN),0)
KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
endif
stackp-flags-y := -fno-stack-protector
stackp-flags-$(CONFIG_STACKPROTECTOR) := -fstack-protector
stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong
KBUILD_CFLAGS += $(stackp-flags-y)
ifdef CONFIG_CC_IS_CLANG
KBUILD_CPPFLAGS += -Qunused-arguments
KBUILD_CFLAGS += -Wno-format-invalid-specifier
KBUILD_CFLAGS += -Wno-gnu
# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
# source of a reference will be _MergedGlobals and not on of the whitelisted names.
# See modpost pattern 2
KBUILD_CFLAGS += -mno-global-merge
else
# These warnings generated too much noise in a regular build.
# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
KBUILD_CFLAGS += -Wno-unused-but-set-variable
# Warn about unmarked fall-throughs in switch statement.
# Disabled for clang while comment to attribute conversion happens and
# https://github.com/ClangBuiltLinux/linux/issues/636 is discussed.
KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough,)
endif
KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
ifdef CONFIG_FRAME_POINTER
KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
else
# Some targets (ARM with Thumb2, for example), can't be built with frame
# pointers. For those, we don't have FUNCTION_TRACER automatically
# select FRAME_POINTER. However, FUNCTION_TRACER adds -pg, and this is
# incompatible with -fomit-frame-pointer with current GCC, so we don't use
# -fomit-frame-pointer with FUNCTION_TRACER.
ifndef CONFIG_FUNCTION_TRACER
KBUILD_CFLAGS += -fomit-frame-pointer
endif
endif
# Initialize all stack variables with a 0xAA pattern.
ifdef CONFIG_INIT_STACK_ALL_PATTERN
KBUILD_CFLAGS += -ftrivial-auto-var-init=pattern
endif
# Initialize all stack variables with a zero value.
ifdef CONFIG_INIT_STACK_ALL_ZERO
# Future support for zero initialization is still being debated, see
# https://bugs.llvm.org/show_bug.cgi?id=45497. These flags are subject to being
# renamed or dropped.
KBUILD_CFLAGS += -ftrivial-auto-var-init=zero
KBUILD_CFLAGS += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
endif
# While VLAs have been removed, GCC produces unreachable stack probes
# for the randomize_kstack_offset feature. Disable it for all compilers.
KBUILD_CFLAGS += $(call cc-option, -fno-stack-clash-protection)
DEBUG_CFLAGS :=
# Workaround for GCC versions < 5.0
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
ifdef CONFIG_CC_IS_GCC
DEBUG_CFLAGS += $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments))
endif
ifdef CONFIG_DEBUG_INFO
ifdef CONFIG_DEBUG_INFO_SPLIT
DEBUG_CFLAGS += -gsplit-dwarf
else
DEBUG_CFLAGS += -g
endif
ifneq ($(LLVM_IAS),1)
KBUILD_AFLAGS += -Wa,-gdwarf-2
endif
ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5
DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y)
endif
ifdef CONFIG_DEBUG_INFO_REDUCED
DEBUG_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
$(call cc-option,-fno-var-tracking)
endif
ifdef CONFIG_DEBUG_INFO_COMPRESSED
DEBUG_CFLAGS += -gz=zlib
KBUILD_AFLAGS += -gz=zlib
KBUILD_LDFLAGS += --compress-debug-sections=zlib
endif
endif # CONFIG_DEBUG_INFO
KBUILD_CFLAGS += $(DEBUG_CFLAGS)
export DEBUG_CFLAGS
ifdef CONFIG_FUNCTION_TRACER
ifdef CONFIG_FTRACE_MCOUNT_USE_CC
CC_FLAGS_FTRACE += -mrecord-mcount
ifdef CONFIG_HAVE_NOP_MCOUNT
ifeq ($(call cc-option-yn, -mnop-mcount),y)
CC_FLAGS_FTRACE += -mnop-mcount
CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
endif
endif
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
ifdef CONFIG_HAVE_C_RECORDMCOUNT
BUILD_C_RECORDMCOUNT := y
export BUILD_C_RECORDMCOUNT
endif
endif
ifdef CONFIG_HAVE_FENTRY
ifeq ($(call cc-option-yn, -mfentry),y)
CC_FLAGS_FTRACE += -mfentry
CC_FLAGS_USING += -DCC_USING_FENTRY
endif
endif
export CC_FLAGS_FTRACE
KBUILD_CFLAGS += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
KBUILD_AFLAGS += $(CC_FLAGS_USING)
endif
# We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH
KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
endif
ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
LDFLAGS_vmlinux += --gc-sections
endif
ifdef CONFIG_SHADOW_CALL_STACK
CC_FLAGS_SCS := -fsanitize=shadow-call-stack
KBUILD_CFLAGS += $(CC_FLAGS_SCS)
export CC_FLAGS_SCS
endif
ifdef CONFIG_LTO_CLANG
ifdef CONFIG_LTO_CLANG_THIN
CC_FLAGS_LTO := -flto=thin -fsplit-lto-unit
KBUILD_LDFLAGS += --thinlto-cache-dir=$(extmod-prefix).thinlto-cache
else
CC_FLAGS_LTO := -flto
endif
CC_FLAGS_LTO += -fvisibility=hidden
# Limit inlining across translation units to reduce binary size
KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
endif
ifdef CONFIG_LTO
KBUILD_CFLAGS += -fno-lto $(CC_FLAGS_LTO)
KBUILD_AFLAGS += -fno-lto
export CC_FLAGS_LTO
endif
ifdef CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_32B
KBUILD_CFLAGS += -falign-functions=32
endif
# arch Makefile may override CC so keep this after arch Makefile is included
NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
# warn about C99 declaration after statement
KBUILD_CFLAGS += -Wdeclaration-after-statement
# Variable Length Arrays (VLAs) should not be used anywhere in the kernel
KBUILD_CFLAGS += -Wvla
# disable pointer signed / unsigned warnings in gcc 4.0
KBUILD_CFLAGS += -Wno-pointer-sign
# disable stringop warnings in gcc 8+
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
# We'll want to enable this eventually, but it's not going away for 5.7 at least
KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
# Another good warning that we'll want to enable eventually
KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
# Enabled with W=2, disabled by default as noisy
KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += -fno-strict-overflow
# Make sure -fstack-check isn't enabled (like gentoo apparently did)
KBUILD_CFLAGS += -fno-stack-check
# conserve stack if available
KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
# Prohibit date/time macros, which would make the build non-deterministic
KBUILD_CFLAGS += -Werror=date-time
# enforce correct pointer usage
KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
# Require designated initializers for all marked structures
KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
# include additional Makefiles when needed
include-y := scripts/Makefile.extrawarn
include-$(CONFIG_KASAN) += scripts/Makefile.kasan
include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan
include-$(CONFIG_UBSAN) += scripts/Makefile.ubsan
include-$(CONFIG_KCOV) += scripts/Makefile.kcov
include-$(CONFIG_GCC_PLUGINS) += scripts/Makefile.gcc-plugins
include $(addprefix $(srctree)/, $(include-y))
# scripts/Makefile.gcc-plugins is intentionally included last.
# Do not add $(call cc-option,...) below this line. When you build the kernel
# from the clean source tree, the GCC plugins do not exist at this point.
# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
KBUILD_CPPFLAGS += $(KCPPFLAGS)
KBUILD_AFLAGS += $(KAFLAGS)
KBUILD_CFLAGS += $(KCFLAGS)
KBUILD_LDFLAGS_MODULE += --build-id=sha1
LDFLAGS_vmlinux += --build-id=sha1
ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
LDFLAGS_vmlinux += $(call ld-option, -X,)
endif
ifeq ($(CONFIG_RELR),y)
LDFLAGS_vmlinux += --pack-dyn-relocs=relr
endif
# We never want expected sections to be placed heuristically by the
# linker. All sections should be explicitly named in the linker script.
ifdef CONFIG_LD_ORPHAN_WARN
LDFLAGS_vmlinux += --orphan-handling=warn
endif
# Align the bit size of userspace programs with the kernel
KBUILD_USERCFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
# make the checker run with the right architecture
CHECKFLAGS += --arch=$(ARCH)
# insure the checker run with the right endianness
CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig-endian,-mlittle-endian)
# the checker needs the correct machine size
CHECKFLAGS += $(if $(CONFIG_64BIT),-m64,-m32)
# Default kernel image to build when no specific target is given.
# KBUILD_IMAGE may be overruled on the command line or
# set in the environment
# Also any assignments in arch/$(ARCH)/Makefile take precedence over
# this default value
export KBUILD_IMAGE ?= vmlinux
#
# INSTALL_PATH specifies where to place the updated kernel and system map
# images. Default is /boot, but you can set it to other values
export INSTALL_PATH ?= /boot
#
# INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
# Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
# an argument if needed. Otherwise it defaults to the kernel install path
#
export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
#
# INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
# relocations required by build roots. This is not defined in the
# makefile but the argument can be passed to make if needed.
#
MODLIB = $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
export MODLIB
#
# INSTALL_MOD_STRIP, if defined, will cause modules to be
# stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
# the default option --strip-debug will be used. Otherwise,
# INSTALL_MOD_STRIP value will be used as the options to the strip command.
ifdef INSTALL_MOD_STRIP
ifeq ($(INSTALL_MOD_STRIP),1)
mod_strip_cmd = $(STRIP) --strip-debug
else
mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
endif # INSTALL_MOD_STRIP=1
else
mod_strip_cmd = true
endif # INSTALL_MOD_STRIP
export mod_strip_cmd
# CONFIG_MODULE_COMPRESS, if defined, will cause module to be compressed
# after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP
# or CONFIG_MODULE_COMPRESS_XZ.
mod_compress_cmd = true
ifdef CONFIG_MODULE_COMPRESS
ifdef CONFIG_MODULE_COMPRESS_GZIP
mod_compress_cmd = $(KGZIP) -n -f
endif # CONFIG_MODULE_COMPRESS_GZIP
ifdef CONFIG_MODULE_COMPRESS_XZ
mod_compress_cmd = $(XZ) --lzma2=dict=2MiB -f
endif # CONFIG_MODULE_COMPRESS_XZ
endif # CONFIG_MODULE_COMPRESS
export mod_compress_cmd
ifdef CONFIG_MODULE_SIG_ALL
$(eval $(call config_filename,MODULE_SIG_KEY))
mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY) certs/signing_key.x509
else
mod_sign_cmd = true
endif
export mod_sign_cmd
HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
has_libelf = $(call try-run,\
echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
ifdef CONFIG_STACK_VALIDATION
ifeq ($(has_libelf),1)
objtool_target := tools/objtool FORCE
else
SKIP_STACK_VALIDATION := 1
export SKIP_STACK_VALIDATION
endif
endif
PHONY += resolve_btfids_clean
resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids
# tools/bpf/resolve_btfids directory might not exist
# in output directory, skip its clean in that case
resolve_btfids_clean:
ifneq ($(wildcard $(resolve_btfids_O)),)
$(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(resolve_btfids_O) clean
endif
ifdef CONFIG_BPF
ifdef CONFIG_DEBUG_INFO_BTF
ifeq ($(has_libelf),1)
resolve_btfids_target := tools/bpf/resolve_btfids FORCE
else
ERROR_RESOLVE_BTFIDS := 1
endif
endif # CONFIG_DEBUG_INFO_BTF
endif # CONFIG_BPF
PHONY += prepare0
extmod-prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)
export MODORDER := $(extmod-prefix)modules.order
export MODULES_NSDEPS := $(extmod-prefix)modules.nsdeps
ifeq ($(KBUILD_EXTMOD),)
core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/
vmlinux-dirs := $(patsubst %/,%,$(filter %/, \
$(core-y) $(core-m) $(drivers-y) $(drivers-m) \
$(libs-y) $(libs-m)))
vmlinux-alldirs := $(sort $(vmlinux-dirs) Documentation \
$(patsubst %/,%,$(filter %/, $(core-) \
$(drivers-) $(libs-))))
subdir-modorder := $(addsuffix modules.order,$(filter %/, \
$(core-y) $(core-m) $(libs-y) $(libs-m) \
$(drivers-y) $(drivers-m)))
build-dirs := $(vmlinux-dirs)
clean-dirs := $(vmlinux-alldirs)
# Externally visible symbols (used by link-vmlinux.sh)
KBUILD_VMLINUX_OBJS := $(head-y) $(patsubst %/,%/built-in.a, $(core-y))
KBUILD_VMLINUX_OBJS += $(addsuffix built-in.a, $(filter %/, $(libs-y)))
ifdef CONFIG_MODULES
KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
else
KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y))
endif
KBUILD_VMLINUX_OBJS += $(patsubst %/,%/built-in.a, $(drivers-y))
export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS
export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
# used by scripts/Makefile.package
export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) LICENSES arch include scripts tools)
vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
# Recurse until adjust_autoksyms.sh is satisfied
PHONY += autoksyms_recursive
ifdef CONFIG_TRIM_UNUSED_KSYMS
# For the kernel to actually contain only the needed exported symbols,
# we have to build modules as well to determine what those symbols are.
# (this can be evaluated only once include/config/auto.conf has been included)
KBUILD_MODULES := 1
autoksyms_recursive: descend modules.order
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
"$(MAKE) -f $(srctree)/Makefile vmlinux"
endif
autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
quiet_cmd_autoksyms_h = GEN $@
cmd_autoksyms_h = mkdir -p $(dir $@); \
$(CONFIG_SHELL) $(srctree)/scripts/gen_autoksyms.sh $@
$(autoksyms_h):
$(call cmd,autoksyms_h)
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
# Final link of vmlinux with optional arch pass after final link
cmd_link-vmlinux = \
$(CONFIG_SHELL) $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
+$(call if_changed,link-vmlinux)
targets := vmlinux
# The actual objects are generated when descending,
# make sure no implicit rule kicks in
$(sort $(vmlinux-deps) $(subdir-modorder)): descend ;
filechk_kernel.release = \
echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
# Store (new) KERNELRELEASE string in include/config/kernel.release
include/config/kernel.release: FORCE
$(call filechk,kernel.release)
# Additional helpers built in scripts/
# Carefully list dependencies so we do not try to build scripts twice
# in parallel
PHONY += scripts
scripts: scripts_basic scripts_dtc
$(Q)$(MAKE) $(build)=$(@)
# Things we need to do before we recursively start building the kernel
# or the modules are listed in "prepare".
# A multi level approach is used. prepareN is processed before prepareN-1.
# archprepare is used in arch Makefiles and when processed asm symlink,
# version.h and scripts_basic is processed / created.
PHONY += prepare archprepare
archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \
asm-generic $(version_h) $(autoksyms_h) include/generated/utsrelease.h \
include/generated/autoconf.h
prepare0: archprepare
$(Q)$(MAKE) $(build)=scripts/mod
$(Q)$(MAKE) $(build)=.
# All the preparing..
prepare: prepare0 prepare-objtool prepare-resolve_btfids
# Support for using generic headers in asm-generic
asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
PHONY += asm-generic uapi-asm-generic
asm-generic: uapi-asm-generic
$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm \
generic=include/asm-generic
uapi-asm-generic:
$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm \
generic=include/uapi/asm-generic
PHONY += prepare-objtool prepare-resolve_btfids
prepare-objtool: $(objtool_target)
ifeq ($(SKIP_STACK_VALIDATION),1)
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
@echo "error: Cannot generate __mcount_loc for CONFIG_DYNAMIC_FTRACE=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
endif
ifdef CONFIG_UNWINDER_ORC
@echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
else
@echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
endif
endif
prepare-resolve_btfids: $(resolve_btfids_target)
ifeq ($(ERROR_RESOLVE_BTFIDS),1)
@echo "error: Cannot resolve BTF IDs for CONFIG_DEBUG_INFO_BTF, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
endif
# Generate some files
# ---------------------------------------------------------------------------
# KERNELRELEASE can change from a few different places, meaning version.h
# needs to be updated, so this check is forced on all builds
uts_len := 64
define filechk_utsrelease.h
if [ `echo -n "$(KERNELRELEASE)" | wc -c ` -gt $(uts_len) ]; then \
echo '"$(KERNELRELEASE)" exceeds $(uts_len) characters' >&2; \
exit 1; \
fi; \
echo \#define UTS_RELEASE \"$(KERNELRELEASE)\"
endef
define filechk_version.h
if [ $(SUBLEVEL) -gt 255 ]; then \
echo \#define LINUX_VERSION_CODE $(shell \
expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + 255); \
else \
echo \#define LINUX_VERSION_CODE $(shell \
expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
fi; \
echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + \
((c) > 255 ? 255 : (c)))'; \
echo \#define LINUX_VERSION_MAJOR $(VERSION); \
echo \#define LINUX_VERSION_PATCHLEVEL $(PATCHLEVEL); \
echo \#define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
endef
$(version_h): PATCHLEVEL := $(if $(PATCHLEVEL), $(PATCHLEVEL), 0)
$(version_h): SUBLEVEL := $(if $(SUBLEVEL), $(SUBLEVEL), 0)
$(version_h): FORCE
$(call filechk,version.h)
include/generated/utsrelease.h: include/config/kernel.release FORCE
$(call filechk,utsrelease.h)
PHONY += headerdep
headerdep:
$(Q)find $(srctree)/include/ -name '*.h' | xargs --max-args 1 \
$(srctree)/scripts/headerdep.pl -I$(srctree)/include
# ---------------------------------------------------------------------------
# Kernel headers
#Default location for installed headers
export INSTALL_HDR_PATH = $(objtree)/usr
quiet_cmd_headers_install = INSTALL $(INSTALL_HDR_PATH)/include
cmd_headers_install = \
mkdir -p $(INSTALL_HDR_PATH); \
rsync -mrl --include='*/' --include='*\.h' --exclude='*' \
usr/include $(INSTALL_HDR_PATH)
PHONY += headers_install
headers_install: headers
$(call cmd,headers_install)
PHONY += archheaders archscripts
hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
PHONY += headers
headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts
$(if $(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/Kbuild),, \
$(error Headers not exportable for the $(SRCARCH) architecture))
$(Q)$(MAKE) $(hdr-inst)=include/uapi
$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
# Deprecated. It is no-op now.
PHONY += headers_check
headers_check:
@:
ifdef CONFIG_HEADERS_INSTALL
prepare: headers
endif
PHONY += scripts_unifdef
scripts_unifdef: scripts_basic
$(Q)$(MAKE) $(build)=scripts scripts/unifdef
# ---------------------------------------------------------------------------
# Kernel selftest
PHONY += kselftest
kselftest:
$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests
kselftest-%: FORCE
$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*
PHONY += kselftest-merge
kselftest-merge:
$(if $(wildcard $(objtree)/.config),, $(error No .config exists, config your kernel first!))
$(Q)find $(srctree)/tools/testing/selftests -name config | \
xargs $(srctree)/scripts/kconfig/merge_config.sh -m $(objtree)/.config
$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
# ---------------------------------------------------------------------------
# Devicetree files
ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
dtstree := arch/$(SRCARCH)/boot/dts
endif
ifneq ($(dtstree),)
%.dtb: include/config/kernel.release scripts_dtc
$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
%.dtbo: include/config/kernel.release scripts_dtc
$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
PHONY += dtbs dtbs_install dtbs_check
dtbs: include/config/kernel.release scripts_dtc
$(Q)$(MAKE) $(build)=$(dtstree)
ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
export CHECK_DTBS=y
dtbs: dt_binding_check
endif
dtbs_check: dtbs
dtbs_install:
$(Q)$(MAKE) $(dtbinst)=$(dtstree) dst=$(INSTALL_DTBS_PATH)
ifdef CONFIG_OF_EARLY_FLATTREE
all: dtbs
endif
endif
PHONY += scripts_dtc
scripts_dtc: scripts_basic
$(Q)$(MAKE) $(build)=scripts/dtc
ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),)
export CHECK_DT_BINDING=y
endif
PHONY += dt_binding_check
dt_binding_check: scripts_dtc
$(Q)$(MAKE) $(build)=Documentation/devicetree/bindings
# ---------------------------------------------------------------------------
# Modules
ifdef CONFIG_MODULES
# By default, build modules as well
all: modules
# When we're building modules with modversions, we need to consider
# the built-in objects during the descend as well, in order to
# make sure the checksums are up to date before we record them.
ifdef CONFIG_MODVERSIONS
KBUILD_BUILTIN := 1
endif
# Build modules
#
# A module can be listed more than once in obj-m resulting in
# duplicate lines in modules.order files. Those are removed
# using awk while concatenating to the final file.
PHONY += modules
modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check modules_prepare
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
PHONY += modules_check
modules_check: modules.order
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
cmd_modules_order = $(AWK) '!x[$$0]++' $(real-prereqs) > $@
modules.order: $(subdir-modorder) FORCE
$(call if_changed,modules_order)
targets += modules.order
# Target to prepare building external modules
PHONY += modules_prepare
modules_prepare: prepare
$(Q)$(MAKE) $(build)=scripts scripts/module.lds
# Target to install modules
PHONY += modules_install
modules_install: _modinst_ _modinst_post
PHONY += _modinst_
_modinst_:
@rm -rf $(MODLIB)/kernel
@rm -f $(MODLIB)/source
@mkdir -p $(MODLIB)/kernel
@ln -s $(abspath $(srctree)) $(MODLIB)/source
@if [ ! $(objtree) -ef $(MODLIB)/build ]; then \
rm -f $(MODLIB)/build ; \
ln -s $(CURDIR) $(MODLIB)/build ; \
fi
@sed 's:^:kernel/:' modules.order > $(MODLIB)/modules.order
@cp -f modules.builtin $(MODLIB)/
@cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
# This depmod is only for convenience to give the initial
# boot a modules.dep even before / is mounted read-write. However the
# boot script depmod is the master version.
PHONY += _modinst_post
_modinst_post: _modinst_
$(call cmd,depmod)
ifeq ($(CONFIG_MODULE_SIG), y)
PHONY += modules_sign
modules_sign:
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modsign
endif
else # CONFIG_MODULES
# Modules not configured
# ---------------------------------------------------------------------------
PHONY += modules modules_install
modules modules_install:
@echo >&2
@echo >&2 "The present kernel configuration has modules disabled."
@echo >&2 "Type 'make config' and enable loadable module support."
@echo >&2 "Then build a kernel with module support enabled."
@echo >&2
@exit 1
endif # CONFIG_MODULES
###
# Cleaning is done on three levels.
# make clean Delete most generated files
# Leave enough to build external modules
# make mrproper Delete the current configuration, and all generated files
# make distclean Remove editor backup files, patch leftover files and the like
# Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers \
modules.builtin modules.builtin.modinfo modules.nsdeps \
compile_commands.json .thinlto-cache
# Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated \
arch/$(SRCARCH)/include/generated .tmp_objdiff \
debian snap tar-install \
.config .config.old .version \
Module.symvers \
signing_key.pem signing_key.priv signing_key.x509 \
x509.genkey extra_certificates signing_key.x509.keyid \
signing_key.x509.signer vmlinux-gdb.py \
*.spec
# Directories & files removed with 'make distclean'
DISTCLEAN_FILES += tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS
# clean - Delete most, but leave enough to build external modules
#
clean: rm-files := $(CLEAN_FILES)
PHONY += archclean vmlinuxclean
vmlinuxclean:
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
$(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
clean: archclean vmlinuxclean resolve_btfids_clean
# mrproper - Delete all generated files, including .config
#
mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
mrproper-dirs := $(addprefix _mrproper_,scripts)
PHONY += $(mrproper-dirs) mrproper
$(mrproper-dirs):
$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
mrproper: clean $(mrproper-dirs)
$(call cmd,rmfiles)
# distclean
#
distclean: rm-files := $(wildcard $(DISTCLEAN_FILES))
PHONY += distclean
distclean: mrproper
$(call cmd,rmfiles)
@find $(srctree) $(RCS_FIND_IGNORE) \
\( -name '*.orig' -o -name '*.rej' -o -name '*~' \
-o -name '*.bak' -o -name '#*#' -o -name '*%' \
-o -name 'core' \) \
-type f -print | xargs rm -f
# Packaging of the kernel to various formats
# ---------------------------------------------------------------------------
%src-pkg: FORCE
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
%pkg: include/config/kernel.release FORCE
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.package $@
# Brief documentation of the typical targets used
# ---------------------------------------------------------------------------
boards := $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*_defconfig)
boards := $(sort $(notdir $(boards)))
board-dirs := $(dir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/*/*_defconfig))
board-dirs := $(sort $(notdir $(board-dirs:/=)))
PHONY += help
help:
@echo 'Cleaning targets:'
@echo ' clean - Remove most generated files but keep the config and'
@echo ' enough build support to build external modules'
@echo ' mrproper - Remove all generated files + config + various backup files'
@echo ' distclean - mrproper + remove editor backup and patch files'
@echo ''
@echo 'Configuration targets:'
@$(MAKE) -f $(srctree)/scripts/kconfig/Makefile help
@echo ''
@echo 'Other generic targets:'
@echo ' all - Build all targets marked with [*]'
@echo '* vmlinux - Build the bare kernel'
@echo '* modules - Build all modules'
@echo ' modules_install - Install all modules to INSTALL_MOD_PATH (default: /)'
@echo ' dir/ - Build all files in dir and below'
@echo ' dir/file.[ois] - Build specified target only'
@echo ' dir/file.ll - Build the LLVM assembly file'
@echo ' (requires compiler support for LLVM assembly generation)'
@echo ' dir/file.lst - Build specified mixed source/assembly target only'
@echo ' (requires a recent binutils and recent build (System.map))'
@echo ' dir/file.ko - Build module including final link'
@echo ' modules_prepare - Set up for building external modules'
@echo ' tags/TAGS - Generate tags file for editors'
@echo ' cscope - Generate cscope index'
@echo ' gtags - Generate GNU GLOBAL index'
@echo ' kernelrelease - Output the release version string (use with make -s)'
@echo ' kernelversion - Output the version stored in Makefile (use with make -s)'
@echo ' image_name - Output the image name (use with make -s)'
@echo ' headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
echo ' (default: $(INSTALL_HDR_PATH))'; \
echo ''
@echo 'Static analysers:'
@echo ' checkstack - Generate a list of stack hogs'
@echo ' versioncheck - Sanity check on version.h usage'
@echo ' includecheck - Check for duplicate included header files'
@echo ' export_report - List the usages of all exported symbols'
@echo ' headerdep - Detect inclusion cycles in headers'
@echo ' coccicheck - Check with Coccinelle'
@echo ' clang-analyzer - Check with clang static analyzer'
@echo ' clang-tidy - Check with clang-tidy'
@echo ''
@echo 'Tools:'
@echo ' nsdeps - Generate missing symbol namespace dependencies'
@echo ''
@echo 'Kernel selftest:'
@echo ' kselftest - Build and run kernel selftest'
@echo ' Build, install, and boot kernel before'
@echo ' running kselftest on it'
@echo ' Run as root for full coverage'
@echo ' kselftest-all - Build kernel selftest'
@echo ' kselftest-install - Build and install kernel selftest'
@echo ' kselftest-clean - Remove all generated kselftest files'
@echo ' kselftest-merge - Merge all the config dependencies of'
@echo ' kselftest to existing .config.'
@echo ''
@$(if $(dtstree), \
echo 'Devicetree:'; \
echo '* dtbs - Build device tree blobs for enabled boards'; \
echo ' dtbs_install - Install dtbs to $(INSTALL_DTBS_PATH)'; \
echo ' dt_binding_check - Validate device tree binding documents'; \
echo ' dtbs_check - Validate device tree source files';\
echo '')
@echo 'Userspace tools targets:'
@echo ' use "make tools/help"'
@echo ' or "cd tools; make help"'
@echo ''
@echo 'Kernel packaging:'
@$(MAKE) -f $(srctree)/scripts/Makefile.package help
@echo ''
@echo 'Documentation targets:'
@$(MAKE) -f $(srctree)/Documentation/Makefile dochelp
@echo ''
@echo 'Architecture specific targets ($(SRCARCH)):'
@$(if $(archhelp),$(archhelp),\
echo ' No architecture specific help defined for $(SRCARCH)')
@echo ''
@$(if $(boards), \
$(foreach b, $(boards), \
printf " %-27s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
echo '')
@$(if $(board-dirs), \
$(foreach b, $(board-dirs), \
printf " %-16s - Show %s-specific targets\\n" help-$(b) $(b);) \
printf " %-16s - Show all of the above\\n" help-boards; \
echo '')
@echo ' make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
@echo ' make V=2 [targets] 2 => give reason for rebuild of target'
@echo ' make O=dir [targets] Locate all output files in "dir", including .config'
@echo ' make C=1 [targets] Check re-compiled c source with $$CHECK'
@echo ' (sparse by default)'
@echo ' make C=2 [targets] Force check of all c source with $$CHECK'
@echo ' make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
@echo ' make W=n [targets] Enable extra build checks, n=1,2,3 where'
@echo ' 1: warnings which may be relevant and do not occur too often'
@echo ' 2: warnings which occur quite often but may still be relevant'
@echo ' 3: more obscure warnings, can most likely be ignored'
@echo ' Multiple levels can be combined with W=12 or W=123'
@echo ''
@echo 'Execute "make" or "make all" to build all targets marked with [*] '
@echo 'For further info see the ./README file'
help-board-dirs := $(addprefix help-,$(board-dirs))
help-boards: $(help-board-dirs)
boards-per-dir = $(sort $(notdir $(wildcard $(srctree)/arch/$(SRCARCH)/configs/$*/*_defconfig)))
$(help-board-dirs): help-%:
@echo 'Architecture specific targets ($(SRCARCH) $*):'
@$(if $(boards-per-dir), \
$(foreach b, $(boards-per-dir), \
printf " %-24s - Build for %s\\n" $*/$(b) $(subst _defconfig,,$(b));) \
echo '')
# Documentation targets
# ---------------------------------------------------------------------------
DOC_TARGETS := xmldocs latexdocs pdfdocs htmldocs epubdocs cleandocs \
linkcheckdocs dochelp refcheckdocs
PHONY += $(DOC_TARGETS)
$(DOC_TARGETS):
$(Q)$(MAKE) $(build)=Documentation $@
# Misc
# ---------------------------------------------------------------------------
PHONY += scripts_gdb
scripts_gdb: prepare0
$(Q)$(MAKE) $(build)=scripts/gdb
$(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
ifdef CONFIG_GDB_SCRIPTS
all: scripts_gdb
endif
else # KBUILD_EXTMOD
###
# External module support.
# When building external modules the kernel used as basis is considered
# read-only, and no consistency checks are made and the make
# system is not used on the basis kernel. If updates are required
# in the basis kernel ordinary make commands (without M=...) must
# be used.
#
# The following are the only valid targets when building external
# modules.
# make M=dir clean Delete all automatically generated files
# make M=dir modules Make all modules in specified dir
# make M=dir Same as 'make M=dir modules'
# make M=dir modules_install
# Install the modules built in the module directory
# Assumes install directory is already created
# We are always building only modules.
KBUILD_BUILTIN :=
KBUILD_MODULES := 1
build-dirs := $(KBUILD_EXTMOD)
PHONY += modules
modules: $(MODORDER)
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
$(MODORDER): descend
@:
PHONY += modules_install
modules_install: _emodinst_ _emodinst_post
install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
PHONY += _emodinst_
_emodinst_:
$(Q)mkdir -p $(MODLIB)/$(install-dir)
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
PHONY += _emodinst_post
_emodinst_post: _emodinst_
$(call cmd,depmod)
compile_commands.json: $(extmod-prefix)compile_commands.json
PHONY += compile_commands.json
clean-dirs := $(KBUILD_EXTMOD)
clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \
$(KBUILD_EXTMOD)/compile_commands.json $(KBUILD_EXTMOD)/.thinlto-cache
PHONY += help
help:
@echo ' Building external modules.'
@echo ' Syntax: make -C path/to/kernel/src M=$$PWD target'
@echo ''
@echo ' modules - default target, build the module(s)'
@echo ' modules_install - install the module'
@echo ' clean - remove generated files in module directory only'
@echo ''
# no-op for external module builds
PHONY += prepare modules_prepare
endif # KBUILD_EXTMOD
# Single targets
# ---------------------------------------------------------------------------
# To build individual files in subdirectories, you can do like this:
#
# make foo/bar/baz.s
#
# The supported suffixes for single-target are listed in 'single-targets'
#
# To build only under specific subdirectories, you can do like this:
#
# make foo/bar/baz/
ifdef single-build
# .ko is special because modpost is needed
single-ko := $(sort $(filter %.ko, $(MAKECMDGOALS)))
single-no-ko := $(sort $(patsubst %.ko,%.mod, $(MAKECMDGOALS)))
$(single-ko): single_modpost
@:
$(single-no-ko): descend
@:
ifeq ($(KBUILD_EXTMOD),)
# For the single build of in-tree modules, use a temporary file to avoid
# the situation of modules_install installing an invalid modules.order.
MODORDER := .modules.tmp
endif
PHONY += single_modpost
single_modpost: $(single-no-ko) modules_prepare
$(Q){ $(foreach m, $(single-ko), echo $(extmod-prefix)$m;) } > $(MODORDER)
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
KBUILD_MODULES := 1
export KBUILD_SINGLE_TARGETS := $(addprefix $(extmod-prefix), $(single-no-ko))
# trim unrelated directories
build-dirs := $(foreach d, $(build-dirs), \
$(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
endif
ifndef CONFIG_MODULES
KBUILD_MODULES :=
endif
# Handle descending into subdirectories listed in $(build-dirs)
# Preset locale variables to speed up the build process. Limit locale
# tweaks to this spot to avoid wrong language settings when running
# make menuconfig etc.
# Error messages still appears in the original language
PHONY += descend $(build-dirs)
descend: $(build-dirs)
$(build-dirs): prepare
$(Q)$(MAKE) $(build)=$@ \
single-build=$(if $(filter-out $@/, $(filter $@/%, $(KBUILD_SINGLE_TARGETS))),1) \
need-builtin=1 need-modorder=1
clean-dirs := $(addprefix _clean_, $(clean-dirs))
PHONY += $(clean-dirs) clean
$(clean-dirs):
$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
clean: $(clean-dirs)
$(call cmd,rmfiles)
@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
\( -name '*.[aios]' -o -name '*.ko' -o -name '.*.cmd' \
-o -name '*.ko.*' \
-o -name '*.dtb' -o -name '*.dtbo' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
-o -name '*.dwo' -o -name '*.lst' \
-o -name '*.su' -o -name '*.mod' \
-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
-o -name '*.lex.c' -o -name '*.tab.[ch]' \
-o -name '*.asn1.[ch]' \
-o -name '*.symtypes' -o -name 'modules.order' \
-o -name '.tmp_*.o.*' \
-o -name '*.c.[012]*.*' \
-o -name '*.ll' \
-o -name '*.gcno' \
-o -name '*.*.symversions' \) -type f -print | xargs rm -f
# Generate tags for editors
# ---------------------------------------------------------------------------
quiet_cmd_tags = GEN $@
cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@
tags TAGS cscope gtags: FORCE
$(call cmd,tags)
# Script to generate missing namespace dependencies
# ---------------------------------------------------------------------------
PHONY += nsdeps
nsdeps: export KBUILD_NSDEPS=1
nsdeps: modules
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps
# Clang Tooling
# ---------------------------------------------------------------------------
quiet_cmd_gen_compile_commands = GEN $@
cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
$(extmod-prefix)compile_commands.json: scripts/clang-tools/gen_compile_commands.py \
$(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)) \
$(if $(CONFIG_MODULES), $(MODORDER)) FORCE
$(call if_changed,gen_compile_commands)
targets += $(extmod-prefix)compile_commands.json
PHONY += clang-tidy clang-analyzer
ifdef CONFIG_CC_IS_CLANG
quiet_cmd_clang_tools = CHECK $<
cmd_clang_tools = $(PYTHON3) $(srctree)/scripts/clang-tools/run-clang-tools.py $@ $<
clang-tidy clang-analyzer: $(extmod-prefix)compile_commands.json
$(call cmd,clang_tools)
else
clang-tidy clang-analyzer:
@echo "$@ requires CC=clang" >&2
@false
endif
# Scripts to check various things for consistency
# ---------------------------------------------------------------------------
PHONY += includecheck versioncheck coccicheck export_report
includecheck:
find $(srctree)/* $(RCS_FIND_IGNORE) \
-name '*.[hcS]' -type f -print | sort \
| xargs $(PERL) -w $(srctree)/scripts/checkincludes.pl
versioncheck:
find $(srctree)/* $(RCS_FIND_IGNORE) \
-name '*.[hcS]' -type f -print | sort \
| xargs $(PERL) -w $(srctree)/scripts/checkversion.pl
coccicheck:
$(Q)$(BASH) $(srctree)/scripts/$@
export_report:
$(PERL) $(srctree)/scripts/export_report.pl
PHONY += checkstack kernelrelease kernelversion image_name
# UML needs a little special treatment here. It wants to use the host
# toolchain, so needs $(SUBARCH) passed to checkstack.pl. Everyone
# else wants $(ARCH), including people doing cross-builds, which means
# that $(SUBARCH) doesn't work here.
ifeq ($(ARCH), um)
CHECKSTACK_ARCH := $(SUBARCH)
else
CHECKSTACK_ARCH := $(ARCH)
endif
checkstack:
$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
$(PERL) $(srctree)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
kernelrelease:
@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
kernelversion:
@echo $(KERNELVERSION)
image_name:
@echo $(KBUILD_IMAGE)
# Clear a bunch of variables before executing the submake
ifeq ($(quiet),silent_)
tools_silent=s
endif
tools/: FORCE
$(Q)mkdir -p $(objtree)/tools
$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/
tools/%: FORCE
$(Q)mkdir -p $(objtree)/tools
$(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ $*
quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN $(wildcard $(rm-files)))
cmd_rmfiles = rm -rf $(rm-files)
# Run depmod only if we have System.map and depmod is executable
quiet_cmd_depmod = DEPMOD $(KERNELRELEASE)
cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
$(KERNELRELEASE)
# read saved command lines for existing targets
existing-targets := $(wildcard $(sort $(targets)))
-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
endif # config-build
endif # mixed-build
endif # need-sub-make
PHONY += FORCE
FORCE:
# Declare the contents of the PHONY variable as phony. We keep that
# information in a variable so we can use it in if_changed and friends.
.PHONY: $(PHONY)
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