On Fri, 18 Sep 2020 10:51:22 +0200 David Hildenbrand <[email protected]> wrote:
> Recent upstream Linux uses the MONITOR CALL instruction for things like > BUG_ON() and WARN_ON(). We currently inject an operation exception when > we hit a MONITOR CALL instruction - which is wrong, as the instruction > is not glued to specific CPU features. > > Doing a simple WARN_ON_ONCE() currently results in a panic: > [ 18.162801] illegal operation: 0001 ilc:2 [#1] SMP > [ 18.162889] Modules linked in: > [...] > [ 18.165476] Kernel panic - not syncing: Fatal exception: panic_on_oops > > With a proper implementation, we now get: > [ 18.242754] ------------[ cut here ]------------ > [ 18.242855] WARNING: CPU: 7 PID: 1 at init/main.c:1534 [...] > [ 18.242919] Modules linked in: > [...] > [ 18.246262] ---[ end trace a420477d71dc97b4 ]--- > [ 18.259014] Freeing unused kernel memory: 4220K > > Reported-by: Christian Borntraeger <[email protected]> > Signed-off-by: David Hildenbrand <[email protected]> > --- > > v1 -> v2: > - Simplify by not using the tb flags, always calling the helper. > > I looked into monitor-event counting, which looks easy at first glance > - but proper DAT/access exception handling is tricky. Leaving that for > a cold winter evening :) Fortunately, this is covered by a facility bit, so no need to do this now :) > > --- > target/s390x/excp_helper.c | 23 +++++++++++++++++++++++ > target/s390x/helper.h | 1 + > target/s390x/insn-data.def | 3 +++ > target/s390x/translate.c | 21 +++++++++++++++++++++ > 4 files changed, 48 insertions(+) Thanks, applied.
