298 lines
11 KiB
Makefile
298 lines
11 KiB
Makefile
# ch5/lkm_template/Makefile
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# ***************************************************************
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# This program is part of the source code released for the book
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# "Linux Kernel Programming" 2E
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# (c) Author: Kaiwan N Billimoria
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# Publisher: Packt
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# GitHub repository:
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# https://github.com/PacktPublishing/Linux-Kernel-Programming_2E
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#
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# From: Ch 5 : Writing Your First Kernel Module LKMs, Part 2
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# ***************************************************************
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# Brief Description:
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# A 'better' Makefile template for Linux LKMs (Loadable Kernel Modules); besides
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# the 'usual' targets (the build, install and clean), we incorporate targets to
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# do useful (and indeed required) stuff like:
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# - adhering to kernel coding style (indent+checkpatch)
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# - several static analysis targets (via sparse, gcc, flawfinder, cppcheck)
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# - two _dummy_ dynamic analysis targets (KASAN, LOCKDEP); just to remind you!
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# - a packaging (.tar.xz) target and
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# - a help target.
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#
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# To get started, just type:
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# make help
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#
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# For details, please refer the book, Ch 5, section
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# 'A "better" Makefile template for your kernel modules'.
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#
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# AUTHOR : Kaiwan N Billimoria
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# DESCRIPTION : A simple kernel module 'better' Makefile template
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# LICENSE : Dual MIT/GPL
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# VERSION : 0.2
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#------------------------------------------------------------------
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# IMPORTANT : Set FNAME_C to the kernel module name source filename (without .c).
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# This enables you to use this Makefile as a template; just update this variable!
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# As well, the MYDEBUG variable (see it below) can be set to 'y' or 'n' (no being
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# the default)
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FNAME_C := modparams1
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ifeq ($(FNAME_C),)
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$(error ERROR: you Must set the FNAME_C variable in the Makefile)
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endif
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#------------------------------------------------------------------
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#--- To support cross-compiling for kernel modules
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# For architecture (cpu) 'arch', invoke make as:
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# make ARCH=<arch> CROSS_COMPILE=<cross-compiler-prefix>
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# F.e. to cross-compile for the AArch64:
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# make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
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#
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# Alternately:
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# export ARCH=<arch>
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# export CROSS_COMPILE=<cross-compiler-prefix>
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# make
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#
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# The KDIR var is set to a sample path below; you're expected to update it on
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# your box to the appropriate path to the kernel source tree for that arch.
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ifeq ($(ARCH),arm)
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# *UPDATE* 'KDIR' below to point to the ARM Linux kernel source tree on your box
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KDIR ?= ~/arm_prj/kernel/linux
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else ifeq ($(ARCH),arm64)
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# *UPDATE* 'KDIR' below to point to the ARM64 (Aarch64) Linux kernel source
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# tree on your box
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KDIR ?= ~/arm64_prj/kernel/linux-5.10.60
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else ifeq ($(ARCH),powerpc)
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# *UPDATE* 'KDIR' below to point to the PPC64 Linux kernel source tree on your box
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KDIR ?= ~/ppc_prj/kernel/linux-5.4
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else
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# 'KDIR' is the Linux 'kernel headers' package on your host system; this is
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# usually an x86_64, but could be anything, really (f.e. building directly
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# on a Raspberry Pi implies that it's the host)
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KDIR ?= /lib/modules/$(shell uname -r)/build
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endif
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#---
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# Compiler
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CC := $(CROSS_COMPILE)gcc
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#CC := clang
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STRIP := ${CROSS_COMPILE}strip
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PWD := $(shell pwd)
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obj-m += ${FNAME_C}.o
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#--- Debug or production mode?
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# Set the MYDEBUG variable accordingly to y/n resp. We keep it off (n) by default.
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# (Actually, debug info is always going to be generated when you build the
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# module on a debug kernel, where CONFIG_DEBUG_INFO is defined, making this
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# setting of the ccflags-y (or the older EXTRA_CFLAGS) variable mostly redundant
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# (besides the still useful -DDEBUG).
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# This simply helps us influence the build on a production kernel, forcing
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# generation of debug symbols, if so required. Also, realize that the DEBUG
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# macro is turned on by many CONFIG_*DEBUG* options; hence, we use a different
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# macro var name, MYDEBUG).
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MYDEBUG := n
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DBG_STRIP := y
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ifeq (${MYDEBUG}, y)
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# https://www.kernel.org/doc/html/latest/kbuild/makefiles.html#compilation-flags
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# EXTRA_CFLAGS deprecated; use ccflags-y
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ccflags-y += -DDEBUG -g -ggdb -gdwarf-4 -Wall -fno-omit-frame-pointer -fvar-tracking-assignments
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DBG_STRIP := n
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else
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ccflags-y += -UDEBUG
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endif
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# We always keep the dynamic debug facility enabled; this allows us to turn
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# dynamically turn on/off debug printk's later... To disable it simply comment
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# out the following line
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ccflags-y += -DDYNAMIC_DEBUG_MODULE
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KMODDIR ?= /lib/modules/$(shell uname -r)
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# Gain access to kernel configs
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-include $(KDIR)/.config
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# Strip the module? Note:
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# a) Only strip debug symbols else it won't load correctly
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# b) WARNING! Don't strip modules when using CONFIG_MODULE_SIG* crytographic security
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ifdef CONFIG_MODULE_SIG
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DBG_STRIP := n
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endif
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ifdef CONFIG_MODULE_SIG_ALL
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DBG_STRIP := n
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endif
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ifdef CONFIG_MODULE_SIG_FORCE
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DBG_STRIP := n
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endif
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all:
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@echo
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@echo '--- Building : KDIR=${KDIR} ARCH=${ARCH} CROSS_COMPILE=${CROSS_COMPILE} ccflags-y="${ccflags-y}" MYDEBUG=${MYDEBUG} DBG_STRIP=${DBG_STRIP} ---'
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@${CC} --version|head -n1
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@echo
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make -C $(KDIR) M=$(PWD) modules
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if [ "${DBG_STRIP}" = "y" ]; then \
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${STRIP} --strip-debug ${FNAME_C}.ko ; \
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fi
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install:
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@echo
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@echo "--- installing ---"
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@echo " [First, invoking the 'make' ]"
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make
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@echo
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@echo " [Now for the 'sudo make install' ]"
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sudo make -C $(KDIR) M=$(PWD) modules_install
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sudo depmod
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@echo " [If !debug and !(module signing), stripping debug info from ${KMODDIR}/extra/${FNAME_C}.ko]"
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if [ "${DBG_STRIP}" = "y" ]; then \
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sudo ${STRIP} --strip-debug ${KMODDIR}/extra/${FNAME_C}.ko ; \
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fi
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nsdeps:
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@echo "--- nsdeps (namespace dependencies resolution; for possibly importing ns's) ---"
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make -C $(KDIR) M=$(PWD) nsdeps
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clean:
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@echo
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@echo "--- cleaning ---"
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@echo
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make -C $(KDIR) M=$(PWD) clean
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# from 'indent'; comment out if you want the backup kept
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rm -f *~
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# Any usermode programs to build? Insert the build target(s) below
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#--------------- More (useful) targets! -------------------------------
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INDENT := indent
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# code-style : "wrapper" target over the following kernel code style targets
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code-style:
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make indent
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make checkpatch
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# indent- "beautifies" C code - to conform to the the Linux kernel
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# coding style guidelines.
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# Note! original source file(s) is overwritten, so we back it up.
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indent:
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ifeq (,$(shell which indent))
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$(error ERROR: install indent first)
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endif
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@echo
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@echo "--- applying kernel code style indentation with indent ---"
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@echo
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mkdir bkp 2> /dev/null; cp -f *.[chsS] bkp/
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${INDENT} -linux --line-length95 *.[chsS]
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# add source files as required
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# Detailed check on the source code styling / etc
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checkpatch:
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make clean
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@echo
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@echo "--- kernel code style check with checkpatch.pl ---"
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@echo
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$(KDIR)/scripts/checkpatch.pl --no-tree -f --max-line-length=95 *.[ch]
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# add source files as required
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#--- Static Analysis
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# sa : "wrapper" target over the following kernel static analyzer targets
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sa:
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make sa_sparse
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make sa_gcc
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make sa_flawfinder
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make sa_cppcheck
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# static analysis with sparse
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sa_sparse:
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ifeq (,$(shell which sparse))
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$(error ERROR: install sparse first)
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endif
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make clean
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@echo
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@echo "--- static analysis with sparse ---"
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@echo
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# If you feel it's too much, use C=1 instead
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# NOTE: deliberately IGNORING warnings from kernel headers!
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make -Wsparse-all C=2 CHECK="/usr/bin/sparse --os=linux --arch=$(ARCH)" -C $(KDIR) M=$(PWD) modules 2>&1 |egrep -v "^\./include/.*\.h|^\./arch/.*\.h"
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# static analysis with gcc
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sa_gcc:
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make clean
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@echo
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@echo "--- static analysis with gcc ---"
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@echo
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make W=1 -C $(KDIR) M=$(PWD) modules
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# static analysis with flawfinder
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sa_flawfinder:
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ifeq (,$(shell which flawfinder))
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$(error ERROR: install flawfinder first)
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endif
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make clean
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@echo
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@echo "--- static analysis with flawfinder ---"
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@echo
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flawfinder *.[ch]
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# static analysis with cppcheck
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sa_cppcheck:
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ifeq (,$(shell which cppcheck))
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$(error ERROR: install cppcheck first)
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endif
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make clean
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@echo
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@echo "--- static analysis with cppcheck ---"
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@echo
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cppcheck -v --force --enable=all -i .tmp_versions/ -i *.mod.c -i bkp/ --suppress=missingIncludeSystem .
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# Packaging: just generates a tar.xz of the source as of now
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tarxz-pkg:
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rm -f ../${FNAME_C}.tar.xz 2>/dev/null
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make clean
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@echo
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@echo "--- packaging ---"
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@echo
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tar caf ../${FNAME_C}.tar.xz *
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ls -l ../${FNAME_C}.tar.xz
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@echo '=== package created: ../$(FNAME_C).tar.xz ==='
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@echo ' TIP: When extracting, to extract into a directory with the same name as the tar file, do this:'
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@echo ' tar -xvf ${FNAME_C}.tar.xz --one-top-level'
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help:
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@echo '=== Makefile Help : additional targets available ==='
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@echo
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@echo 'TIP: Type make <tab><tab> to show all valid targets'
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@echo 'FYI: KDIR=${KDIR} ARCH=${ARCH} CROSS_COMPILE=${CROSS_COMPILE} ccflags-y="${ccflags-y}" MYDEBUG=${MYDEBUG} DBG_STRIP=${DBG_STRIP}'
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@echo
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@echo '--- 'usual' kernel LKM targets ---'
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@echo 'typing "make" or "all" target : builds the kernel module object (the .ko)'
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@echo 'install : installs the kernel module(s) to INSTALL_MOD_PATH (default here: /lib/modules/$(shell uname -r)/).'
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@echo ' : Takes care of performing debug-only symbols stripping iff MYDEBUG=n and not using module signature'
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@echo 'nsdeps : namespace dependencies resolution; for possibly importing namespaces'
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@echo 'clean : cleanup - remove all kernel objects, temp files/dirs, etc'
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@echo
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@echo '--- kernel code style targets ---'
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@echo 'code-style : "wrapper" target over the following kernel code style targets'
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@echo ' indent : run the $(INDENT) utility on source file(s) to indent them as per the kernel code style'
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@echo ' checkpatch : run the kernel code style checker tool on source file(s)'
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@echo
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@echo '--- kernel static analyzer targets ---'
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@echo 'sa : "wrapper" target over the following kernel static analyzer targets'
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@echo ' sa_sparse : run the static analysis sparse tool on the source file(s)'
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@echo ' sa_gcc : run gcc with option -W1 ("Generally useful warnings") on the source file(s)'
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@echo ' sa_flawfinder : run the static analysis flawfinder tool on the source file(s)'
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@echo ' sa_cppcheck : run the static analysis cppcheck tool on the source file(s)'
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@echo 'TIP: use Coccinelle as well: https://www.kernel.org/doc/html/v6.1/dev-tools/coccinelle.html'
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@echo
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@echo '--- kernel dynamic analysis targets ---'
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@echo 'da_kasan : DUMMY target: this is to remind you to run your code with the dynamic analysis KASAN tool enabled; requires configuring the kernel with CONFIG_KASAN On, rebuild and boot it'
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@echo 'da_lockdep : DUMMY target: this is to remind you to run your code with the dynamic analysis LOCKDEP tool (for deep locking issues analysis) enabled; requires configuring the kernel with CONFIG_PROVE_LOCKING On, rebuild and boot it'
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@echo 'TIP: Best to build a debug kernel with several kernel debug config options turned On, boot via it and run all your test cases'
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@echo
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@echo '--- misc targets ---'
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@echo 'tarxz-pkg : tar and compress the LKM source files as a tar.xz into the dir above; allows one to transfer and build the module on another system'
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@echo ' TIP: When extracting, to extract into a directory with the same name as the tar file, do this:'
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@echo ' tar -xvf ${FNAME_C}.tar.xz --one-top-level'
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@echo 'help : this help target'
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