arm64: unhandled level 0 translation fault

[Will Deacon]

On Fri, Dec 15, 2017 at 04:59:28PM +0100, Geert Uytterhoeven wrote:
> On Fri, Dec 15, 2017 at 3:27 PM, Will Deacon <will.deacon at arm.com> wrote:
> > On Fri, Dec 15, 2017 at 02:30:00PM +0100, Geert Uytterhoeven wrote:
> >> On Fri, Dec 15, 2017 at 12:23 PM, Dave Martin <Dave.Martin at arm.com> wrote:
> >> > The two important differences here seem to be
> >> >
> >> > 1) Staging the state via current->thread.fpsimd_state instead of loading
> >> > directly:
> >> >
> >> > -       fpsimd_load_state(state);
> >> > +       current->thread.fpsimd_state = *state;
> >> > +       fpsimd_load_state(&current->thread.fpsimd_state);
> >>
> >> The change above introduces the breakage.
> >
> > I finally managed to reproduce this, but only by using the exact same
> > compiler as Geert:
> >
> > https://www.kernel.org/pub/tools/crosstool/files/bin/x86_64/4.9.0/x86_64-gcc-4.9.0-nolibc_aarch64-linux.tar.xz
> >
> > I then reliably see the problem if I run:
> >
> >   # /usr/bin/update-ca-certificates
> 
> /usr/sbin/... ?
> 
> > from Debian Jessie.
> 
> Funny, I've just got both
> 
>     *** Error in `/bin/sh': free(): invalid pointer: 0x0000aaaac17d4988 ***
> 
> and
> 
>     mountall.sh[2172]: unhandled level 0 translation fault (11) at
> 0x0000004d, esr 0x92000004, in dash[aaaace7e5000+1a000]
> 
> during boot up, but I can't get update-ca-certificates to fail...

Can you try the diff below, please?

Will

--->8

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 540a1e010eb5..fae81f7964b4 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1043,7 +1043,7 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
 
        local_bh_disable();
 
-       current->thread.fpsimd_state = *state;
+       current->thread.fpsimd_state.user_fpsimd = state->user_fpsimd;
        if (system_supports_sve() && test_thread_flag(TIF_SVE))
                fpsimd_to_sve(current);