linux-kernel - Re: arm64: unhandled level 0 translation fault

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Message-ID: <20171215160623.GQ25650@arm.com>
Date:   Fri, 15 Dec 2017 16:06:23 +0000
From:   Will Deacon <will.deacon@....com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Dave Martin <Dave.Martin@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <Catalin.Marinas@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Alex Bennée <alex.bennee@...aro.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: arm64: unhandled level 0 translation fault

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@....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@....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);