torture: Improve diagnostic for KCSAN-incapable compilers

Using --kcsan when the compiler does not support KCSAN results in this:

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16

This is a bit obtuse, so this commit adds checks resulting in this:

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Compiler or architecture does not support KCSAN!
Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?

Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Marco Elver <elver@google.com>

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
index 357899c..840a467 100755 (executable)
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
@@ -44,7 +44,8 @@ do
                        then
                                echo QEMU killed
                        fi
-                       configcheck.sh $i/.config $i/ConfigFragment
+                       configcheck.sh $i/.config $i/ConfigFragment > $T 2>&1
+                       cat $T
                        if test -r $i/Make.oldconfig.err
                        then
                                cat $i/Make.oldconfig.err
@@ -73,7 +74,11 @@ do
        done
        if test -f "$rd/kcsan.sum"
        then
-               if test -s "$rd/kcsan.sum"
+               if grep -q CONFIG_KCSAN=y $T
+               then
+                       echo "Compiler or architecture does not support KCSAN!"
+                       echo Did you forget to switch your compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?
+               elif test -s "$rd/kcsan.sum"
                then
                        echo KCSAN summary in $rd/kcsan.sum
                else