Date:   Thu, 26 May 2022 09:24:01 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Jessica Clarke <jrtc27@...c27.com>,
        Palmer Dabbelt <palmer@...osinc.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Guenter Roeck <linux@...ck-us.net>,
        Palmer Dabbelt <palmer@...belt.com>,
        Heiko Stübner <heiko@...ech.de>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH V2] riscv: compat: Using seperated vdso_maps for compat_vdso_info

On Thu, May 26, 2022 at 9:00 AM Jessica Clarke <jrtc27@...c27.com> wrote:
>
> On 26 May 2022, at 01:33, guoren@...nel.org wrote:
> >
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > This is a fixup for vdso implementation which caused musl to
> > fail.
> >
> > [   11.600082] Run /sbin/init as init process
> > [   11.628561] init[1]: unhandled signal 11 code 0x1 at
> > 0x0000000000000000 in libc.so[ffffff8ad39000+a4000]
> > [   11.629398] CPU: 0 PID: 1 Comm: init Not tainted
> > 5.18.0-rc7-next-20220520 #1
> > [   11.629462] Hardware name: riscv-virtio,qemu (DT)
> > [   11.629546] epc : 00ffffff8ada1100 ra : 00ffffff8ada13c8 sp :
> > 00ffffffc58199f0
> > [   11.629586]  gp : 00ffffff8ad39000 tp : 00ffffff8ade0998 t0 :
> > ffffffffffffffff
> > [   11.629598]  t1 : 00ffffffc5819fd0 t2 : 0000000000000000 s0 :
> > 00ffffff8ade0cc0
> > [   11.629610]  s1 : 00ffffff8ade0cc0 a0 : 0000000000000000 a1 :
> > 00ffffffc5819a00
> > [   11.629622]  a2 : 0000000000000001 a3 : 000000000000001e a4 :
> > 00ffffffc5819b00
> > [   11.629634]  a5 : 00ffffffc5819b00 a6 : 0000000000000000 a7 :
> > 0000000000000000
> > [   11.629645]  s2 : 00ffffff8ade0ac8 s3 : 00ffffff8ade0ec8 s4 :
> > 00ffffff8ade0728
> > [   11.629656]  s5 : 00ffffff8ade0a90 s6 : 0000000000000000 s7 :
> > 00ffffffc5819e40
> > [   11.629667]  s8 : 00ffffff8ade0ca0 s9 : 00ffffff8addba50 s10:
> > 0000000000000000
> > [   11.629678]  s11: 0000000000000000 t3 : 0000000000000002 t4 :
> > 0000000000000001
> > [   11.629688]  t5 : 0000000000020000 t6 : ffffffffffffffff
> > [   11.629699] status: 0000000000004020 badaddr: 0000000000000000
> > cause: 000000000000000d
> >
> > The last __vdso_init(&compat_vdso_info) replaces the data in normal
> > vdso_info. This is an obvious bug.
> >
> > Reported-by: Guenter Roeck <linux@...ck-us.net>
> > Tested-by: Guenter Roeck <linux@...ck-us.net>
> > Tested-by: Heiko Stübner <heiko@...ech.de>
> > Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren@...nel.org>
> > Cc: Palmer Dabbelt <palmer@...belt.com>
> > ---
> > Changes in V2:
> > - Add Tested-by
> > - Rename vvar & vdso in /proc/<pid>/maps.
>
> Why? No other architecture renames it to that, and various pieces of
> software look for the magic [vdso] name, including GDB and LLDB, though
> by my count there are 57 source packages in Debian that contain the
> string literal "[vdso]" (including quotes), including Firefox,
> Android's ART, lvm2 and elfutils.
Opps, Thx for pointing this out. Abandon the version of the patch. @Palmer

>
> Jess
>
> > ---
> > arch/riscv/kernel/vdso.c | 15 +++++++++++++--
> > 1 file changed, 13 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
> > index 50fe4c877603..957f164c9778 100644
> > --- a/arch/riscv/kernel/vdso.c
> > +++ b/arch/riscv/kernel/vdso.c
> > @@ -206,12 +206,23 @@ static struct __vdso_info vdso_info __ro_after_init = {
> > };
> >
> > #ifdef CONFIG_COMPAT
> > +static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
> > +     [RV_VDSO_MAP_VVAR] = {
> > +             .name   = "[compat vvar]",
> > +             .fault = vvar_fault,
> > +     },
> > +     [RV_VDSO_MAP_VDSO] = {
> > +             .name   = "[compat vdso]",
> > +             .mremap = vdso_mremap,
> > +     },
> > +};
> > +
> > static struct __vdso_info compat_vdso_info __ro_after_init = {
> >       .name = "compat_vdso",
> >       .vdso_code_start = compat_vdso_start,
> >       .vdso_code_end = compat_vdso_end,
> > -     .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> > -     .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> > +     .dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> > +     .cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> > };
> > #endif
> >
> > --
> > 2.36.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

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