[PATCH V2] riscv: compat: Using seperated vdso_maps for compat_vdso_info

[Palmer Dabbelt]

On Wed, 25 May 2022 18:24:01 PDT (-0700), guoren at kernel.org wrote:
> On Thu, May 26, 2022 at 9:00 AM Jessica Clarke <jrtc27 at jrtc27.com> wrote:
>>
>> On 26 May 2022, at 01:33, guoren at kernel.org wrote:
>> >
>> > From: Guo Ren <guoren at linux.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 at roeck-us.net>
>> > Tested-by: Guenter Roeck <linux at roeck-us.net>
>> > Tested-by: Heiko Stübner <heiko at sntech.de>
>> > Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
>> > Signed-off-by: Guo Ren <guoren at kernel.org>
>> > Cc: Palmer Dabbelt <palmer at dabbelt.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

OK, I'll stick with the v1 I had -- everything was still in staging 
anyway, though the tests probably wouldn't have found this one as I 
don't run any of those (I'm just running buildroot's defaults).

>
>>
>> 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
>> >
>> >
>> > _______________________________________________
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>> > linux-riscv at lists.infradead.org
>> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>>
>
>
> -- 
> Best Regards
>  Guo Ren
>
> ML: https://lore.kernel.org/linux-csky/