initial buildability of full libwolfssl.ko loadable kernel module for Linux via ./configure --enable-linuxkm && make.

.gitignore

@@ -229,6 +229,15 @@ IDE/MDK-ARM/LPC43xx/LPC43xx/
 *.gcno
 *.gcda
 *.gcov
+!linuxkm/Makefile
+/Kbuild
+linuxkm/*.ko
+linuxkm/Module.symvers
+linuxkm/built-in.a
+linuxkm/modules.order
+linuxkm/wolfcrypt
+linuxkm/libwolfssl.mod
+linuxkm/libwolfssl.mod.c
 
 # MPLAB Generated Files (OS X)
 mcapi/wolfcrypt_mcapi.X/nbproject/Makefile-*

Makefile.am

@@ -195,7 +195,8 @@ endif
 include scripts/include.am
 
 if BUILD_LINUXKM
-SUBDIRS = . linuxkm
+export KROOT KARCH AM_CFLAGS CFLAGS AM_CCASFLAGS CCASFLAGS src_libwolfssl_la_OBJECTS
+SUBDIRS = linuxkm
 endif
 
 if USE_VALGRIND

configure.ac

@@ -3381,16 +3381,18 @@ then
         [AS_HELP_STRING([--with-linux-source=PATH],[PATH to root of Linux kernel build tree])],
         [KROOT=$withval],
         [KROOT=$DEFAULT_KROOT])
+    AC_SUBST([KROOT])
 
     AC_DEFAULT_KERNEL_ARCH
     AC_ARG_WITH([linux-arch],
         [AS_HELP_STRING([--with-linux-arch=arch],[built arch (SRCARCH) of Linux kernel build tree])],
         [KARCH=$withval],
         [KARCH=$DEFAULT_KARCH])
+    AC_SUBST([KARCH])
 
-    AC_DEFINE_KERNEL_KFLAGS
-
-    AM_CPPFLAGS="$KFLAGS $AM_CPPFLAGS"
+#    AC_DEFINE_KERNEL_KFLAGS
+#
+#    AM_CPPFLAGS="$KFLAGS $AM_CPPFLAGS"
 fi
 
 
@@ -5413,7 +5415,7 @@ AC_SUBST([LIB_STATIC_ADD])
 
 # FINAL
 AC_CONFIG_FILES([stamp-h], [echo timestamp > stamp-h])
-AC_CONFIG_FILES([Makefile wolfssl/version.h wolfssl/options.h cyassl/options.h support/wolfssl.pc rpm/spec linuxkm/Makefile])
+AC_CONFIG_FILES([Makefile wolfssl/version.h wolfssl/options.h cyassl/options.h support/wolfssl.pc rpm/spec])
 
 AX_CREATE_GENERIC_CONFIG
 AX_AM_JOBSERVER([yes])
@@ -5665,8 +5667,7 @@ echo "   * Small Stack:                $ENABLED_SMALL_STACK"
 echo "   * Linux Kernel Module:        $ENABLED_LINUXKM"
 test "$ENABLED_LINUXKM" = "yes" && \
 echo "   * Linux Kernel Build Root:    $KROOT" && \
-echo "   * Linux Kernel Build Arch:    $KARCH" && \
-echo "   * Linux Kernel Build Flags:   $KFLAGS"
+echo "   * Linux Kernel Build Arch:    $KARCH"
 echo "   * valgrind unit tests:        $ENABLED_VALGRIND"
 echo "   * LIBZ:                       $ENABLED_LIBZ"
 echo "   * Examples:                   $ENABLED_EXAMPLES"

linuxkm/Kbuild

@@ -0,0 +1,29 @@
+# libwolfssl Kbuild
+
+# wolfcrypto asm provokes many objtool complaints:
+# "call without frame pointer save/setup",
+# "BP used as a scratch register",
+# "indirect jump found in RETPOLINE build",
+# and "is missing an ELF size annotation"
+# see /usr/src/linux/tools/objtool/Documentation/stack-validation.txt
+OBJECT_FILES_NON_STANDARD := y
+
+obj-m := libwolfssl.o
+
+ifeq "$(WOLFSSL_OBJ_FILES)" ""
+$(error $$WOLFSSL_OBJ_FILES is unset.)
+endif
+
+ifeq "$(WOLFSSL_CFLAGS)" ""
+$(error $$WOLFSSL_CFLAGS is unset.)
+endif
+
+ifeq "$(WOLFSSL_ASFLAGS)" ""
+$(error $$WOLFSSL_ASFLAGS is unset.)
+endif
+
+libwolfssl-y := $(WOLFSSL_OBJ_FILES)
+
+ccflags-y := $(WOLFSSL_CFLAGS)
+
+asflags-y := $(WOLFSSL_ASFLAGS)

linuxkm/Makefile

@@ -0,0 +1,38 @@
+all: libwolfssl.ko
+
+.PHONY: libwolfssl.ko
+
+ifndef MODULE_TOP
+MODULE_TOP=$(CURDIR)
+endif
+
+ifndef SRC_TOP
+SRC_TOP=$(shell dirname $(MODULE_TOP))
+endif
+
+ifeq "$(KROOT)" ""
+$(error $$KROOT is unset.)
+endif
+
+ifeq "$(AM_CFLAGS)$(CFLAGS)" ""
+$(error $$AM_CFLAGS and $$CFLAGS are both unset.)
+endif
+
+ifeq "$(AM_CCASFLAGS)$(CCASFLAGS)" ""
+$(error $$AM_CCASFLAGS and $$CCASFLAGS are both unset.)
+endif
+
+ifeq "$(src_libwolfssl_la_OBJECTS)" ""
+$(error $$src_libwolfssl_la_OBJECTS is unset.)
+endif
+
+WOLFSSL_CFLAGS=-DHAVE_CONFIG_H -I$(SRC_TOP) -DBUILDING_WOLFSSL $(AM_CFLAGS) $(CFLAGS) -Wframe-larger-than=262144
+WOLFSSL_ASFLAGS=-DHAVE_CONFIG_H -I$(SRC_TOP) -DBUILDING_WOLFSSL $(AM_CCASFLAGS) $(CCASFLAGS)
+WOLFSSL_OBJ_FILES=linuxkm/module_hooks.o $(patsubst %.lo, %.o, $(patsubst src/libwolfssl_la-%, src/%, $(patsubst wolfcrypt/src/src_libwolfssl_la-%, wolfcrypt/src/%, $(src_libwolfssl_la_OBJECTS))))
+
+export WOLFSSL_CFLAGS WOLFSSL_ASFLAGS WOLFSSL_OBJ_FILES
+
+libwolfssl.ko:
+	@mkdir -p linuxkm src wolfcrypt/src
+	@if [[ ! -h $(SRC_TOP)/Kbuild ]]; then ln -s $(MODULE_TOP)/Kbuild $(SRC_TOP)/Kbuild; fi
+	make -C $(KROOT) M=$(MODULE_TOP) src=$(SRC_TOP)

linuxkm/Makefile.am

@@ -1,5 +0,0 @@
-EXTRA_PROGRAMS = automake_dummy
-automake_dummy_SOURCES = wolfssl_linuxkm.c
-module_DATA = wolfssl_linuxkm.o
-#include ../Makefile.common
-include Makefile.common

linuxkm/Makefile.common

@@ -1,20 +0,0 @@
-# Makefile.common
-moduledir = @moduledir@
-KERNEL_LOCATION=@kerneldir@
-KBUILD_VERBOSE = 1
-MOD_DEVDIR = $(PWD)
-
-export module_DATA
-
-$(module_DATA): $(automake_dummy_SOURCES)
-	echo "not building kernel module yet"
-
-#	mv Makefile Makefile.automake
-#	cp $(srcdir)/../Makefile.kernel Makefile
-#	CPPFLAGS="" CFLAGS="" LDFLAGS="" \
-#	$(MAKE) -C $(KROOT) \
-#	ARCH="$KARCH" CC="gcc" M=$(PWD) modules\
-#		KBUILD_VERBOSE=$(KBUILD_VERBOSE)
-#	mv Makefile.automake Makefile
-
-CLEANFILES = $(module_DATA) .$(module_DATA).flags $(module_DATA:.o=.mod.c) $(module_DATA:.o=.@kernelext@) *~

linuxkm/module_hooks.c

@@ -0,0 +1,43 @@
+/* http://h-wrt.com/en/mini-how-to/autotoolsSimpleModule */
+
+/*  src/module_hello.c */
+
+#ifdef HAVE_CONFIG_H
+    #include <config.h>
+#endif
+
+#include <wolfssl/wolfcrypt/settings.h>
+#include <wolfssl/wolfcrypt/error-crypt.h>
+#include <wolfssl/ssl.h>
+
+static int __init wolfssl_init(void)
+{
+    int ret = wolfSSL_Init();
+    if (ret != WOLFSSL_SUCCESS) {
+        pr_err("wolfSSL_Init() failed: %s", wc_GetErrorString(ret));
+        return -ENOTRECOVERABLE;
+    }
+
+    pr_info("wolfSSL " LIBWOLFSSL_VERSION_STRING " loaded. See https://www.wolfssl.com/ for information.\n");
+    pr_info("Copyright (C) 2006-2020 wolfSSL Inc. All Rights Reserved.\n");
+
+    return 0;
+}
+
+module_init(wolfssl_init);
+
+static void __exit wolfssl_exit(void)
+{
+    int ret = wolfSSL_Cleanup();
+    if (ret != WOLFSSL_SUCCESS)
+        pr_err("wolfSSL_Cleanup() failed: %s", wc_GetErrorString(ret));
+
+    return;
+}
+
+module_exit(wolfssl_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("https://www.wolfssl.com/");
+MODULE_DESCRIPTION("libwolfssl cryptographic and protocol facilities");
+MODULE_VERSION(LIBWOLFSSL_VERSION_STRING);

linuxkm/wolfssl_linuxkm.c

@@ -1,28 +0,0 @@
-/* http://h-wrt.com/en/mini-how-to/autotoolsSimpleModule */
-
-/*  src/module_hello.c */
-
-#include <linux/init.h>
-#include <linux/module.h>
-
-static int __init
-hello_init(void)
-{
-   printk("Hello, world!\n");
-   return 0;
-}
-
-module_init(hello_init);
-
-static void __exit
-hello_exit(void)
-{
-   printk("Goodbye, world!\n");
-}
-
-module_exit(hello_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("noname ");
-MODULE_DESCRIPTION("\"Hello, world!\" test module");
-MODULE_VERSION("printk");

m4/ax_linuxkm.m4

@@ -28,14 +28,15 @@ else
 fi
 ])
 
-AC_DEFUN([AC_DEFINE_KERNEL_KFLAGS],
-[
-    AC_MSG_CHECKING([flags for compiling objects for kernel module])
-    if test -z "${KROOT}" || test -z "${KARCH}"; then
-        AC_MSG_ERROR([Linux kernel configuration incomplete (KROOT=${KROOT}, KARCH=${KARCH}).])
-    else
-        GCC_SHORT_VERSION="$($CC -dumpversion)"
-        KFLAGS="-I${KROOT}/include -I${KROOT}/include/uapi -I${KROOT}/arch/${KARCH}/include -I${KROOT}/arch/${KARCH}/include/generated -I${KROOT}/arch/${KARCH}/include/generated/uapi -I${KROOT}/arch/${KARCH}/include/uapi -I${KROOT}/tools/include -I${KROOT}/tools/arch/${KARCH}/include -I${KROOT}/tools/include/uapi -I/usr/lib/gcc/${host_cpu}-${host_vendor}-${host_os}/${GCC_SHORT_VERSION}/include"
-        AC_MSG_RESULT([$KFLAGS])
-    fi
-])
+dnl AC_DEFUN([AC_DEFINE_KERNEL_KFLAGS],
+dnl [
+dnl     AC_MSG_CHECKING([flags for compiling objects for kernel module])
+dnl     if test -z "${KROOT}" || test -z "${KARCH}"; then
+dnl         AC_MSG_ERROR([Linux kernel configuration incomplete (KROOT=${KROOT}, KARCH=${KARCH}).])
+dnl     else
+dnl         GCC_SHORT_VERSION="$($CC -dumpversion)"
+dnl         KFLAGS="-I${KROOT}/include -I${KROOT}/include/uapi -I${KROOT}/arch/${KARCH}/include -I${KROOT}/arch/${KARCH}/include/generated -I${KROOT}/arch/${KARCH}/include/generated/uapi -I${KROOT}/arch/${KARCH}/include/uapi -I${KROOT}/tools/include -I${KROOT}/tools/arch/${KARCH}/include -I${KROOT}/tools/include/uapi -I/usr/lib/gcc/${host_cpu}-${host_vendor}-${host_os}/${GCC_SHORT_VERSION}/include"
+dnl         AC_MSG_RESULT([$KFLAGS])
+dnl     fi
+dnl ])
+dnl