Initial commit - simple list demo
This commit is contained in:
Kaiwan N Billimoria
297
ch6/list_demo/Makefile
Normal file
297
ch6/list_demo/Makefile
Normal file
@@ -0,0 +1,297 @@
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# 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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||||
# ***************************************************************
|
||||
# Brief Description:
|
||||
# A 'better' Makefile template for Linux LKMs (Loadable Kernel Modules); besides
|
||||
# the 'usual' targets (the build, install and clean), we incorporate targets to
|
||||
# do useful (and indeed required) stuff like:
|
||||
# - adhering to kernel coding style (indent+checkpatch)
|
||||
# - several static analysis targets (via sparse, gcc, flawfinder, cppcheck)
|
||||
# - 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 := list_demo
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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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||||
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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
|
||||
# tree on your box
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||||
KDIR ?= ~/arm64_prj/kernel/linux-5.10.60
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else ifeq ($(ARCH),powerpc)
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||||
# *UPDATE* 'KDIR' below to point to the PPC64 Linux kernel source tree on your box
|
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KDIR ?= ~/ppc_prj/kernel/linux-5.4
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else
|
||||
# 'KDIR' is the Linux 'kernel headers' package on your host system; this is
|
||||
# usually an x86_64, but could be anything, really (f.e. building directly
|
||||
# on a Raspberry Pi implies that it's the host)
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KDIR ?= /lib/modules/$(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 += ${FNAME_C}.o
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||||
|
||||
#--- Debug or production mode?
|
||||
# Set the MYDEBUG variable accordingly to y/n resp. We keep it off (n) by default.
|
||||
# (Actually, debug info is always going to be generated when you build the
|
||||
# module on a debug kernel, where CONFIG_DEBUG_INFO is defined, making this
|
||||
# setting of the ccflags-y (or the older EXTRA_CFLAGS) variable mostly redundant
|
||||
# (besides the still useful -DDEBUG).
|
||||
# This simply helps us influence the build on a production kernel, forcing
|
||||
# generation of debug symbols, if so required. Also, realize that the DEBUG
|
||||
# macro is turned on by many CONFIG_*DEBUG* options; hence, we use a different
|
||||
# macro var name, MYDEBUG).
|
||||
MYDEBUG := n
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||||
DBG_STRIP := y
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||||
ifeq (${MYDEBUG}, y)
|
||||
# https://www.kernel.org/doc/html/latest/kbuild/makefiles.html#compilation-flags
|
||||
# EXTRA_CFLAGS deprecated; use ccflags-y
|
||||
ccflags-y += -DDEBUG -g -ggdb -gdwarf-4 -Wall -fno-omit-frame-pointer -fvar-tracking-assignments
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||||
DBG_STRIP := n
|
||||
else
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||||
ccflags-y += -UDEBUG
|
||||
endif
|
||||
# We always keep the dynamic debug facility enabled; this allows us to turn
|
||||
# dynamically turn on/off debug printk's later... To disable it simply comment
|
||||
# out the following line
|
||||
ccflags-y += -DDYNAMIC_DEBUG_MODULE
|
||||
KMODDIR ?= /lib/modules/$(shell uname -r)
|
||||
|
||||
# Gain access to kernel configs
|
||||
include $(KDIR)/.config
|
||||
|
||||
# Strip the module? Note:
|
||||
# a) Only strip debug symbols else it won't load correctly
|
||||
# b) WARNING! Don't strip modules when using CONFIG_MODULE_SIG* crytographic security
|
||||
ifdef CONFIG_MODULE_SIG
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||||
DBG_STRIP := n
|
||||
endif
|
||||
ifdef CONFIG_MODULE_SIG_ALL
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||||
DBG_STRIP := n
|
||||
endif
|
||||
ifdef CONFIG_MODULE_SIG_FORCE
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||||
DBG_STRIP := n
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||||
endif
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||||
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||||
|
||||
all:
|
||||
@echo
|
||||
@echo '--- Building : KDIR=${KDIR} ARCH=${ARCH} CROSS_COMPILE=${CROSS_COMPILE} ccflags-y="${ccflags-y}" MYDEBUG=${MYDEBUG} DBG_STRIP=${DBG_STRIP} ---'
|
||||
@${CC} --version|head -n1
|
||||
@echo
|
||||
make -C $(KDIR) M=$(PWD) modules
|
||||
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
|
||||
@echo "--- installing ---"
|
||||
@echo " [First, invoking the 'make' ]"
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make
|
||||
@echo
|
||||
@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]"
|
||||
if [ "${DBG_STRIP}" = "y" ]; then \
|
||||
sudo ${STRIP} --strip-debug ${KMODDIR}/extra/${FNAME_C}.ko ; \
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||||
fi
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||||
nsdeps:
|
||||
@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:
|
||||
@echo
|
||||
@echo "--- cleaning ---"
|
||||
@echo
|
||||
make -C $(KDIR) M=$(PWD) clean
|
||||
# from 'indent'; comment out if you want the backup kept
|
||||
rm -f *~
|
||||
|
||||
# Any usermode programs to build? Insert the build target(s) below
|
||||
|
||||
|
||||
#--------------- 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
|
||||
|
||||
# indent- "beautifies" C code - to conform to the the Linux kernel
|
||||
# coding style guidelines.
|
||||
# Note! original source file(s) is overwritten, so we back it up.
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||||
indent:
|
||||
ifeq (,$(shell which indent))
|
||||
$(error ERROR: install indent first)
|
||||
endif
|
||||
@echo
|
||||
@echo "--- applying kernel code style indentation with indent ---"
|
||||
@echo
|
||||
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
|
||||
|
||||
# Detailed check on the source code styling / etc
|
||||
checkpatch:
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||||
make clean
|
||||
@echo
|
||||
@echo "--- kernel code style check with checkpatch.pl ---"
|
||||
@echo
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||||
$(KDIR)/scripts/checkpatch.pl --no-tree -f --max-line-length=95 *.[ch]
|
||||
# add source files as required
|
||||
|
||||
#--- Static Analysis
|
||||
# sa : "wrapper" target over the following kernel static analyzer targets
|
||||
sa:
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||||
make sa_sparse
|
||||
make sa_gcc
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||||
make sa_flawfinder
|
||||
make sa_cppcheck
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||||
|
||||
# static analysis with sparse
|
||||
sa_sparse:
|
||||
ifeq (,$(shell which sparse))
|
||||
$(error ERROR: install sparse first)
|
||||
endif
|
||||
make clean
|
||||
@echo
|
||||
@echo "--- static analysis with sparse ---"
|
||||
@echo
|
||||
# If you feel it's too much, use C=1 instead
|
||||
# NOTE: deliberately IGNORING warnings from kernel headers!
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||||
make -Wsparse-all C=2 CHECK="/usr/bin/sparse --os=linux --arch=$(ARCH)" -C $(KDIR) M=$(PWD) modules 2>&1 |egrep -v "^\./include/.*\.h|^\./arch/.*\.h"
|
||||
|
||||
# static analysis with gcc
|
||||
sa_gcc:
|
||||
make clean
|
||||
@echo
|
||||
@echo "--- static analysis with gcc ---"
|
||||
@echo
|
||||
make W=1 -C $(KDIR) M=$(PWD) modules
|
||||
|
||||
# static analysis with flawfinder
|
||||
sa_flawfinder:
|
||||
ifeq (,$(shell which flawfinder))
|
||||
$(error ERROR: install flawfinder first)
|
||||
endif
|
||||
make clean
|
||||
@echo
|
||||
@echo "--- static analysis with flawfinder ---"
|
||||
@echo
|
||||
flawfinder *.[ch]
|
||||
|
||||
# static analysis with cppcheck
|
||||
sa_cppcheck:
|
||||
ifeq (,$(shell which cppcheck))
|
||||
$(error ERROR: install cppcheck first)
|
||||
endif
|
||||
make clean
|
||||
@echo
|
||||
@echo "--- static analysis with cppcheck ---"
|
||||
@echo
|
||||
cppcheck -v --force --enable=all -i .tmp_versions/ -i *.mod.c -i bkp/ --suppress=missingIncludeSystem .
|
||||
|
||||
# Packaging: just generates a tar.xz of the source as of now
|
||||
tarxz-pkg:
|
||||
rm -f ../${FNAME_C}.tar.xz 2>/dev/null
|
||||
make clean
|
||||
@echo
|
||||
@echo "--- packaging ---"
|
||||
@echo
|
||||
tar caf ../${FNAME_C}.tar.xz *
|
||||
ls -l ../${FNAME_C}.tar.xz
|
||||
@echo '=== package created: ../$(FNAME_C).tar.xz ==='
|
||||
@echo ' TIP: When extracting, to extract into a directory with the same name as the tar file, do this:'
|
||||
@echo ' tar -xvf ${FNAME_C}.tar.xz --one-top-level'
|
||||
|
||||
help:
|
||||
@echo '=== Makefile Help : additional targets available ==='
|
||||
@echo
|
||||
@echo 'TIP: Type make <tab><tab> to show all valid targets'
|
||||
@echo 'FYI: KDIR=${KDIR} ARCH=${ARCH} CROSS_COMPILE=${CROSS_COMPILE} ccflags-y="${ccflags-y}" MYDEBUG=${MYDEBUG} DBG_STRIP=${DBG_STRIP}'
|
||||
|
||||
@echo
|
||||
@echo '--- 'usual' kernel LKM targets ---'
|
||||
@echo 'typing "make" or "all" target : builds the kernel module object (the .ko)'
|
||||
@echo 'install : installs the kernel module(s) to INSTALL_MOD_PATH (default here: /lib/modules/$(shell uname -r)/).'
|
||||
@echo ' : Takes care of performing debug-only symbols stripping iff MYDEBUG=n and not using module signature'
|
||||
@echo 'nsdeps : namespace dependencies resolution; for possibly importing namespaces'
|
||||
@echo 'clean : cleanup - remove all kernel objects, temp files/dirs, etc'
|
||||
|
||||
@echo
|
||||
@echo '--- kernel code style targets ---'
|
||||
@echo 'code-style : "wrapper" target over the following kernel code style targets'
|
||||
@echo ' indent : run the $(INDENT) utility on source file(s) to indent them as per the kernel code style'
|
||||
@echo ' checkpatch : run the kernel code style checker tool on source file(s)'
|
||||
|
||||
@echo
|
||||
@echo '--- kernel static analyzer targets ---'
|
||||
@echo 'sa : "wrapper" target over the following kernel static analyzer targets'
|
||||
@echo ' sa_sparse : run the static analysis sparse tool on the source file(s)'
|
||||
@echo ' sa_gcc : run gcc with option -W1 ("Generally useful warnings") on the source file(s)'
|
||||
@echo ' sa_flawfinder : run the static analysis flawfinder tool on the source file(s)'
|
||||
@echo ' sa_cppcheck : run the static analysis cppcheck tool on the source file(s)'
|
||||
@echo 'TIP: use Coccinelle as well: https://www.kernel.org/doc/html/v6.1/dev-tools/coccinelle.html'
|
||||
|
||||
@echo
|
||||
@echo '--- kernel dynamic analysis targets ---'
|
||||
@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'
|
||||
@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'
|
||||
@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'
|
||||
|
||||
@echo
|
||||
@echo '--- misc targets ---'
|
||||
@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'
|
||||
@echo ' TIP: When extracting, to extract into a directory with the same name as the tar file, do this:'
|
||||
@echo ' tar -xvf ${FNAME_C}.tar.xz --one-top-level'
|
||||
@echo 'help : this help target'
|
||||
156
ch6/list_demo/list_demo.c
Normal file
156
ch6/list_demo/list_demo.c
Normal file
@@ -0,0 +1,156 @@
|
||||
/*
|
||||
* ch6/list_demo/list_demo.c
|
||||
***************************************************************
|
||||
* This program is part of the source code released for the book
|
||||
* "Linux Kernel Programming" 2E
|
||||
* (c) Author: Kaiwan N Billimoria
|
||||
* Publisher: Packt
|
||||
* GitHub repository:
|
||||
* https://github.com/PacktPublishing/Linux-Kernel-Programming_2E
|
||||
*
|
||||
* From: Ch 6: Kernel Internals Essentials - Processes and Threads
|
||||
****************************************************************
|
||||
* Brief Description:
|
||||
* A simple module to demo the basics of using the kernel's 'famous'
|
||||
* linked list macros and routines.
|
||||
* Ref: https://www.kernel.org/doc/html/latest/core-api/kernel-api.html#list-management-functions
|
||||
*
|
||||
* For details, please refer the book, Ch 6.
|
||||
* License: Dual MIT/GPL
|
||||
*/
|
||||
#define pr_fmt(fmt) "%s:%s(): " fmt, KBUILD_MODNAME, __func__
|
||||
|
||||
#include <linux/init.h>
|
||||
#include <linux/kernel.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/list.h>
|
||||
|
||||
MODULE_AUTHOR("Kaiwan N Billimoria");
|
||||
MODULE_DESCRIPTION("A simple Linux kernel linked list usage demo");
|
||||
MODULE_LICENSE("Dual MIT/GPL"); // or whatever
|
||||
MODULE_VERSION("0.1");
|
||||
|
||||
LIST_HEAD(head_node);
|
||||
struct node {
|
||||
struct list_head list; /* first member should be this one; it has
|
||||
* the pointers to next and prev
|
||||
*/
|
||||
int ival1, ival2;
|
||||
s8 letter;
|
||||
};
|
||||
|
||||
static int add2tail(int v1, int v2, s8 achar)
|
||||
{
|
||||
struct node *mynode = NULL;
|
||||
|
||||
mynode = kzalloc(sizeof(struct node), GFP_KERNEL);
|
||||
if (!mynode)
|
||||
return -ENOMEM;
|
||||
mynode->ival1 = v1;
|
||||
mynode->ival2 = v2;
|
||||
mynode->letter = achar;
|
||||
|
||||
INIT_LIST_HEAD(&mynode->list);
|
||||
// void list_add_tail(struct list_head *new, struct list_head *head)
|
||||
list_add_tail(&mynode->list, &head_node);
|
||||
pr_info("Added a node (with letter '%c') to the list...\n", achar);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void showlist(void)
|
||||
{
|
||||
//struct list_head *ptr;
|
||||
struct node *curr;
|
||||
|
||||
if (list_empty(&head_node))
|
||||
return;
|
||||
|
||||
pr_info(" val1 | val2 | letter\n");
|
||||
#if 0
|
||||
list_for_each(ptr, &head_node) {
|
||||
curr = list_entry(ptr, struct node, list); // wrapper over container_of()
|
||||
#else
|
||||
// simpler: internally invokes __container_of() to get the ptr to curr struct
|
||||
list_for_each_entry(curr, &head_node, list) {
|
||||
#endif
|
||||
pr_info("%9d %9d %c\n",
|
||||
curr->ival1, curr->ival2, curr->letter);
|
||||
}
|
||||
}
|
||||
|
||||
/* Works, but is O(n) */
|
||||
static void findinlist_letter(s8 char2locate)
|
||||
{
|
||||
struct node *curr;
|
||||
int i = 0;
|
||||
bool found = false;
|
||||
|
||||
if (list_empty(&head_node))
|
||||
return;
|
||||
|
||||
pr_info("Searching list for letter '%c'...\n", char2locate);
|
||||
list_for_each_entry(curr, &head_node, list) {
|
||||
if (curr->letter == char2locate) {
|
||||
found = true;
|
||||
pr_info("found '%c' @ node #%d:\n"
|
||||
"%9d %9d _%c_\n",
|
||||
char2locate, i, curr->ival1, curr->ival2, curr->letter);
|
||||
}
|
||||
i++;
|
||||
}
|
||||
if (!found)
|
||||
pr_info("Didn't find '%c' in list\n", char2locate);
|
||||
}
|
||||
|
||||
static void freelist(void)
|
||||
{
|
||||
struct node *curr;
|
||||
|
||||
if (list_empty(&head_node))
|
||||
return;
|
||||
|
||||
pr_info("freeing list items...\n");
|
||||
list_for_each_entry(curr, &head_node, list)
|
||||
kfree(curr);
|
||||
}
|
||||
|
||||
static int __init list_init(void)
|
||||
{
|
||||
#if 0
|
||||
struct module mymod;
|
||||
#endif
|
||||
|
||||
/* Add a few nodes to the tail of the list */
|
||||
add2tail(1, 2, 'l');
|
||||
add2tail(5, 1000, 'i');
|
||||
add2tail(3, 1415, 's');
|
||||
add2tail(jiffies, jiffies+msecs_to_jiffies(300), 't');
|
||||
|
||||
// display the list items
|
||||
showlist();
|
||||
|
||||
// search for some items in the list
|
||||
findinlist_letter('s');
|
||||
findinlist_letter('z');
|
||||
|
||||
/* Iterate over all modules?
|
||||
* Fails as struct module is not available (!exported) to module authors!
|
||||
*/
|
||||
#if 0
|
||||
list_for_each_entry(module.list, THIS_MODULE, list)
|
||||
pr_info("module: %s\n", mymod->name);
|
||||
#endif
|
||||
|
||||
return 0; /* success */
|
||||
}
|
||||
|
||||
static void __exit list_exit(void)
|
||||
{
|
||||
freelist();
|
||||
pr_info("removed\n");
|
||||
}
|
||||
|
||||
module_init(list_init);
|
||||
module_exit(list_exit);
|
||||
Reference in New Issue
Block a user