Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <CACT4Y+bDqMiC+ou5ghb=XB3Oyjw3p-GTDvNw4NkkQqQthw1yuQ@mail.gmail.com>
 <mhng-02b88d43-ede8-48f9-82f1-c84201acb7a8@palmerdabbelt-glaptop>
 <CACT4Y+aN3LvgaBc_zmW=t=D7ChU-jrWYnjt5sZ2GEDQhg_BC9A@mail.gmail.com>
 <CACT4Y+aC19DaNOm87EO3cER2=MEmO9pmtUxzVmRtg9YhZKuMVA@mail.gmail.com>
 <20210118145310.crnqnh6kax5jqicj@distanz.ch> <CACT4Y+bFV6m1LCYb1nO7ioKJK99916D76sJ+H-LgBjWx6biF5w@mail.gmail.com>
 <CACT4Y+bmDKNnykeTP9yKjje3XZjbXY3De+_e3fMFOMoe0dnARw@mail.gmail.com>
 <6e9ee3a1-0e16-b1fc-a690-f1ca8e9823a5@ghiti.fr> <CACT4Y+adSjve7bXRPh5UybCQx6ubOUu5RbwuT620wdcxHzVYJg@mail.gmail.com>
In-Reply-To: <CACT4Y+adSjve7bXRPh5UybCQx6ubOUu5RbwuT620wdcxHzVYJg@mail.gmail.com>
From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Tue, 16 Feb 2021 12:17:30 +0100
Message-ID: <CACT4Y+ZNJBnkKHXUf=tm_yuowvZvHwN=0rmJ=7J+xFd+9r_6pQ@mail.gmail.com>
Subject: Re: riscv+KASAN does not boot
To:     Alex Ghiti <alex@ghiti.fr>
Cc:     Tobias Klauser <tklauser@distanz.ch>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Bjorn Topel <bjorn.topel@gmail.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        LKML <linux-kernel@vger.kernel.org>, nylon7@andestech.com,
        syzkaller <syzkaller@googlegroups.com>,
        Andreas Schwab <schwab@linux-m68k.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        linux-riscv <linux-riscv@lists.infradead.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Jan 29, 2021 at 9:11 AM Dmitry Vyukov <dvyukov@google.com> wrote:
> > I was fixing KASAN support for my sv48 patchset so I took a look at your
> > issue: I built a kernel on top of the branch riscv/fixes using
> > https://github.com/google/syzkaller/blob/269d24e857a757d09a898086a2fa6fa5d827c3e1/dashboard/config/linux/upstream-riscv64-kasan.config
> > and Buildroot 2020.11. I have the warnings regarding the use of
> > __virt_to_phys on wrong addresses (but that's normal since this function
> > is used in virt_addr_valid) but not the segfaults you describe.
>
> Hi Alex,
>
> Let me try to rebuild buildroot image. Maybe there was something wrong
> with my build, though, I did 'make clean' before doing. But at the
> same time it worked back in June...
>
> Re WARNINGs, they indicate kernel bugs. I am working on setting up a
> syzbot instance on riscv. If there a WARNING during boot then the
> kernel will be marked as broken. No further testing will happen.
> Is it a mis-use of WARN_ON? If so, could anybody please remove it or
> replace it with pr_err.


Hi,

I've localized one issue with riscv/KASAN:
KASAN breaks VDSO and that's I think the root cause of weird faults I
saw earlier. The following patch fixes it.
Could somebody please upstream this fix? I don't know how to add/run
tests for this.
Thanks

diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index 0cfd6da784f84..cf3a383c1799d 100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -35,6 +35,7 @@ CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
 # Disable gcov profiling for VDSO code
 GCOV_PROFILE := n
 KCOV_INSTRUMENT := n
+KASAN_SANITIZE := n

 # Force dependency
 $(obj)/vdso.o: $(obj)/vdso.so