On Tue, Jun 16, 2020 at 06:42:02PM +0200, Marco Elver wrote:
> On Tue, Jun 16 2020 at 09:05AM -0700, Paul E. McKenney wrote:
>
> > On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> > > We need to pass the arguments provided to --kmake-arg to all make
> > > invocations. In particular, the make invocations generating the configs
> > > need to see the final make arguments, e.g. if config variables depend on
> > > particular variables that are passed to make.
> > >
> > > For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> > > CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> > > compiler that supports KCSAN.
> > >
> > > Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
> >
> > Queued and pushed, thank you!
> >
> > Would the following patch make sense, at least until such time
> > as some other compiler supports KCSAN?
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
> > Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Date: Tue Jun 16 09:02:34 2020 -0700
> >
> > torture: Make --kcsan default to using Clang 11
> >
> > Currently, Clang 11 is the only compiler that can support KCSAN.
> > Therefore, as a convenience to the KCSAN user, this commit causes
> > --kcsan to specify Clang 11 unless a "CC=" argument was already
> > specified via the --kmake-arg argument.
>
> As soon as more compilers support KCSAN (e.g. clang-12, etc...) we run
> the risk of actually inconveniencing ourselves more because then we
> really need to say '--kmake-arg CC=clang-1X' to not use the old
> compiler. Or revert this in time.
>
> My command-line looks more like this right now:
>
> kvm.sh ... --kmake-arg "CC="${HOME}/local/<gcc-or-clang>-11.kcsan/local/bin/<gcc-or-clang>" ...
>
> I think the safer alternative would be to error if CONFIG_KCSAN=y is not
> in the config, and simply suggest "Did you forget to switch your
> compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?" (of course, a
> 'gcc' in $PATH that supports KCSAN would also be fine -- see below).
> Eventually, when the default compilers support KCSAN, this will resolve
> itself gracefully.
>
> Also, I'm going to send a series later this week to re-enable GCC
> support. ;-)
OK, sounds like I should leave well enough alone, then. ;-)
In its current state, specifying "--kcsan" without a KCSAN-capable
compiler does get you 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
Which admittedly is a bit obtuse, especially that last line. So how
about the following patch, which instead 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
Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?
Thanx, Paul
------------------------------------------------------------------------
commit f571795b1146007407851675a258b6685ea2d589
Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
Date: Tue Jun 16 10:38:57 2020 -0700
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
Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?
Suggested-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
index 357899c..837643a 100755
--- 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 $i/Make.oldconfig.err
@@ -73,7 +74,10 @@ do
done
if test -f "$rd/kcsan.sum"
then
- if test -s "$rd/kcsan.sum"
+ if grep -q CONFIG_KCSAN=y $T
+ then
+ echo Did you forget to switch your compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?
+ elif test -s "$rd/kcsan.sum"
then
echo KCSAN summary in $rd/kcsan.sum
else
