Re: [PATCH v5 0/2] target/s390x: Fix SIGILL/SIGFPE/SIGTRAP psw.addr reporting

[Ulrich Weigand]

On Fri, Jul 02, 2021 at 02:01:47PM +0200, Laurent Vivier wrote:
> Le 02/07/2021 à 12:34, Cornelia Huck a écrit :
> > On Wed, Jun 23 2021, Ilya Leoshkevich <iii@linux.ibm.com> wrote:
> > 
> >> qemu-s390x puts a wrong value into SIGILL's siginfo_t's psw.addr: it
> >> should be a pointer to the instruction following the illegal
> >> instruction, but at the moment it is a pointer to the illegal
> >> instruction itself. This breaks OpenJDK, which relies on this value.
> >> A similar problem exists for SIGFPE and SIGTRAP.
> >>
> >> Patch 1 fixes the issue, patch 2 adds a test.
> >>
> >> v1: https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg06592.html
> >> v1 -> v2: Use a better buglink (Cornelia), simplify the inline asm
> >>           magic in the test and add an explanation (David).
> >>
> >> v2: https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg06649.html
> >> v2 -> v3: Fix SIGSEGV handling (found when trying to run valgrind under
> >>           qemu-user).
> >>
> >> v3: https://lists.nongnu.org/archive/html/qemu-devel/2021-06/msg00299.html
> >> v3 -> v4: Fix compiling the test on Ubuntu 20.04 (Jonathan).
> >>
> >> v4: https://lists.nongnu.org/archive/html/qemu-devel/2021-06/msg05848.html
> >> v4 -> v5: Greatly simplify the fix (Ulrich).
> >>
> >> Note: the compare-and-trap SIGFPE issue is being fixed separately.
> >> https://lists.nongnu.org/archive/html/qemu-devel/2021-06/msg05690.html
> >>
> >> Ilya Leoshkevich (2):
> >>   target/s390x: Fix SIGILL/SIGFPE/SIGTRAP psw.addr reporting
> >>   tests/tcg/s390x: Test SIGILL and SIGSEGV handling
> >>
> >>  linux-user/s390x/cpu_loop.c     |   5 +
> >>  tests/tcg/s390x/Makefile.target |   1 +
> >>  tests/tcg/s390x/signal.c        | 165 ++++++++++++++++++++++++++++++++
> >>  3 files changed, 171 insertions(+)
> >>  create mode 100644 tests/tcg/s390x/signal.c
> > 
> > What's the status of this and
> > <20210621141452.2045-1-jonathan.albrecht@linux.vnet.ibm.com>? linux-user
> > is not really my turf, but it would be sad if this fell through the
> > cracks.
> > 
> 
> If from the S390x point of view they are correct, I can collect them via 
> linux-user.

It's certainly correct that SIGILL, SIGFPE and SIGTRAP are delivered with 
psw.addr
pointing *after* the faulting instruction, that forms in effect part of the 
kernel
ABI on s390x.  We're planning to document this in the next revision of the ABI
document, see here: https://github.com/IBM/s390x-abi/issues/2

I can also confirm that this patch fixes the problems I was seeing when running
the s390x wasmtime JIT under qemu.

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  Ulrich.Weigand@de.ibm.com