[RFC PATCH] x86/kconfig: Sanity-check config file during oldconfig

[Borislav Petkov]

From: Borislav Petkov <bp@xxxxxxx>

Thomas Voegtle reported that doing oldconfig with a .config which has
CONFIG_MICROCODE enabled but BLK_DEV_INITRD disabled prevents the
microcode loading mechanism from being built.

Add a short script which hooks into the "make oldconfig" handling and
sanity-checks the config file for that discrepancy. It issues a message
which should hopefully sensitize the user to that issue and point her
into the right direction.

The other useful thing with this solution is that it can be extended to
other config file sanity-checking, should the need arise.

Reported-by: Thomas Voegtle <tv@xxxxxxxx>
Cc: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
Cc: MÃns RullgÃrd <mans@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
 arch/x86/scripts/check-configs.sh | 44 +++++++++++++++++++++++++++++++++++++++
 scripts/kconfig/Makefile          |  3 +++
 2 files changed, 47 insertions(+)
 create mode 100644 arch/x86/scripts/check-configs.sh

diff --git a/arch/x86/scripts/check-configs.sh b/arch/x86/scripts/check-configs.sh
new file mode 100644
index 000000000000..775d07e37df5
--- /dev/null
+++ b/arch/x86/scripts/check-configs.sh
@@ -0,0 +1,44 @@
+#!/bin/bash
+
+if [ "$1" != "oldconfig" ]; then
+	exit 0
+fi
+
+srctree=$2
+ARCH="$3"
+UNAME_RELEASE=$(uname -r)
+
+CONFIGS=".config /lib/modules/$UNAME_RELEASE/.config /etc/kernel-config /boot/config-$UNAME_RELEASE"
+
+if [ "$ARCH" = "X86_32" ]; then
+	CONFIGS="$CONFIGS $srctree/arch/x86/configs/i386_defconfig"
+else
+	CONFIGS="$CONFIGS $srctree/arch/x86/configs/x86_64_defconfig"
+fi
+
+for c in $CONFIGS;
+do
+	if [ -e $c ]; then
+		OLD_CONFIG=$c
+		break
+	fi
+done
+
+if [ -z "$OLD_CONFIG" ]; then exit 0; fi
+
+# Check optimal microcode loader .config settings
+if ! grep -v "^#" $OLD_CONFIG | grep -q MICROCODE; then
+	exit 0
+fi
+
+MSG="\nYou have CONFIG_MICROCODE enabled without BLK_DEV_INITRD. The preferred\n\
+way is to enable it and make sure microcode is added to your initrd as\n\
+explained in Documentation/x86/early-microcode.txt. This is also the\n\
+most tested method as the majority of distros do it. Alternatively, and\n\
+if you don't want to enable modules, you should make sure the microcode\n\
+is built into the kernel.\n"
+
+if ! grep -v "^#" $OLD_CONFIG | grep -q BLK_DEV_INITRD; then
+	echo -e $MSG
+	read -p "Press any key... "
+fi
diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index d79cba4ce3eb..136ae9744efc 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -81,6 +81,9 @@ simple-targets := oldconfig allnoconfig allyesconfig allmodconfig \
 PHONY += $(simple-targets)
 
 $(simple-targets): $(obj)/conf
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/scripts/check-configs.sh),)
+	$(Q)$(CONFIG_SHELL) $(srctree)/arch/$(SRCARCH)/scripts/check-configs.sh $@ $(srctree) $(ARCH)
+endif
 	$< $(silent) --$@ $(Kconfig)
 
 PHONY += oldnoconfig savedefconfig defconfig
-- 
2.3.5

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