On Fri, 23 Apr 2021 15:28:19 +0200
Thomas Huth <th...@redhat.com> wrote:
> On 23/04/2021 15.06, Peter Maydell wrote:
> > On Fri, 23 Apr 2021 at 13:22, Cornelia Huck <coh...@redhat.com> wrote:
> >>
> >> On Thu, 22 Apr 2021 16:44:27 +0100
> >> Alex Bennée <alex.ben...@linaro.org> wrote:
> >>
> >>> We can remove PAGE_WRITE when (internally) marking a page read-only
> >>> because it contains translated code. This can get confused when we are
> >>> executing signal return code on signal stacks.
> >>>
> >>> Fixes: e56552cf07 ("target/s390x: Implement the MVPG
> >>> condition-code-option bit")
> >>> Found-by: Richard Henderson <richard.hender...@linaro.org>
> >>> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
> >>> Cc: Cornelia Huck <coh...@redhat.com>
> >>> Cc: Thomas Huth <th...@redhat.com>
> >>> Cc: David Hildenbrand <da...@redhat.com>
> >>> Cc: Laurent Vivier <laur...@vivier.eu>
> >>> ---
> >>> target/s390x/mem_helper.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> >>> index 12e84a4285..f6a7d29273 100644
> >>> --- a/target/s390x/mem_helper.c
> >>> +++ b/target/s390x/mem_helper.c
> >>> @@ -145,7 +145,7 @@ static int s390_probe_access(CPUArchState *env,
> >>> target_ulong addr, int size,
> >>>
> >>> #if defined(CONFIG_USER_ONLY)
> >>> flags = page_get_flags(addr);
> >>> - if (!(flags & (access_type == MMU_DATA_LOAD ? PAGE_READ :
> >>> PAGE_WRITE))) {
> >>> + if (!(flags & (access_type == MMU_DATA_LOAD ? PAGE_READ :
> >>> PAGE_WRITE_ORG))) {
> >>> env->__excp_addr = addr;
> >>> flags = (flags & PAGE_VALID) ? PGM_PROTECTION : PGM_ADDRESSING;
> >>> if (nonfault) {
> >>
> >> What's the verdict on this one? I plan to queue this to s390-next; but
> >> if we end up doing an -rc5, it might qualify as a regression fix.
> >
> > What's your opinion? I think we do need an rc5 for the network backend
> > hotplug crash. I don't want to open the doors for lots of new fixes
> > just because we've got another rc, but on the other hand this one
> > does look like it's a pretty small and safe fix, and letting intermittent
> > crash bugs out into the wild seems like it could lead to a lot of
> > annoying re-investigation of the same bug if it's reported by users
> > later... So I kind of lean towards putting it in rc5.
>
> IMHO: It's in a s390x-only file, within a #ifdef CONFIG_USER_ONLY ... so the
> damage this could do is very, very limited, indeed. Thus I'd also suggest to
> include it in a rc5.
Exactly, the benefits outweigh the risk IMHO.
Peter, do you want to pick this one directly, or should I send you a pull req?
