From 66f77080950dceffef6023054629a208a15220cd Mon Sep 17 00:00:00 2001
From: Vincent Brillault <vincent.brillault@cern.ch>
Date: Mon, 8 Jan 2018 12:39:03 +0100
Subject: [PATCH] Refactor RedHat support: - Isolate file check to different
 elif (allowing to add more) - Do the PTI debugfs check first (faster and
 supposed to be dynamic) - If pti_enable is 0, don't trust dmesg (supposed to
 be dynamic)

---
 spectre-meltdown-checker.sh | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/spectre-meltdown-checker.sh b/spectre-meltdown-checker.sh
index 367b3e0..f809e0d 100755
--- a/spectre-meltdown-checker.sh
+++ b/spectre-meltdown-checker.sh
@@ -171,15 +171,20 @@ if [ ! -e /sys/kernel/debug/sched_features ]; then
 	# try to mount the debugfs hierarchy ourselves and remember it to umount afterwards
 	mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
 fi
-if [ -e /sys/kernel/debug/ibrs_enabled -o -e /sys/kernel/debug/x86/ibrs_enabled ]; then
+if [ -e /sys/kernel/debug/ibrs_enabled ]; then
 	# if the file is there, we have IBRS compiled-in
 	pstatus green YES
 	ibrs_supported=1
+	ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
+elif [ -e /sys/kernel/debug/x86/ibrs_enabled ]; then
+	# RedHat uses a different path (see https://access.redhat.com/articles/3311301)
+	pstatus green YES
+	ibrs_supported=1
+	ibrs_enabled=$(cat /sys/kernel/debug/x86/ibrs_enabled 2>/dev/null)
 else
 	pstatus red NO
 fi
 
-[ -f /sys/kernel/debug/ibrs_enabled ] && ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null) || ibrs_enabled=$(cat /sys/kernel/debug/x86/ibrs_enabled 2>/dev/null)
 /bin/echo -n "*   IBRS enabled for Kernel space: "
 # 0 means disabled
 # 1 is enabled only for kernel space
@@ -285,13 +290,17 @@ if grep ^flags /proc/cpuinfo | grep -qw pti; then
 	# vanilla PTI patch sets the 'pti' flag in cpuinfo
 	pstatus green YES
 	kpti_enabled=1
+elif [ -e /sys/kernel/debug/x86/pti_enabled ]; then
+	# RedHat Backport creates a dedicated file, see https://access.redhat.com/articles/3311301
+	kpti_enabled=$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null)
 elif dmesg | grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled'; then
 	# if we can't find the flag, grep in dmesg
-	pstatus green YES
 	kpti_enabled=1
-elif [ -e /sys/kernel/debug/x86/pti_enabled -a "$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null)" = 1 ]; then
+else
+	kpti_enabled=0
+fi
+if [ "$kpti_enabled" = 1 ]; then
 	pstatus green YES
-	kpti_enabled=1
 else
 	pstatus red NO
 fi