On 01/12/2022 21.51, Richard Henderson wrote:
On 12/1/22 10:44, Thomas Huth wrote:
The SET ADDRESS SPACE CONTROL FAST instruction is not privileged, it can be
used from problem space, too. Just the switching to the home address space
is privileged and should still generate a privilege exception. This bug is
e.g. causing programs like Java that use the "getcpu" vdso kernel function
to crash (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=990417#26 ).
While we're at it, also check if DAT is not enabled. In that case the
instruction is supposed to generate a special operation exception.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/655
Signed-off-by: Thomas Huth <th...@redhat.com>
---
Looks ok, as far as it goes. We appear to be missing the check for
CR0_SECONDARY, which is unpredictable for SACF but mandatory for SAC.
Yes, but if I got our sources right, we do not implement SAC yet. Looks like
Linux does not use it, so nobody bothered to implement it yet. Since it
should be very similar to SACF, it should be easy to add - I can try to come
up with an additional patch for it later.
I'll give you
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
for fixing the incorrect IF_PRIV check, which by itself should be enough to
fix the Java issue.
Thanks!
Thomas
PS: We might have a similar bug with the MVCP and MVCS instructions ...
seems like they could be called from userspace in certain situations, too.
