linux-kernel - Re: [PATCH] riscv: compat: Using seperated vdso_maps for compat_vdso

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Message-ID: <48ef770c-75bf-6c37-66fe-9719164bc6e0@roeck-us.net>
Date:   Wed, 25 May 2022 15:56:07 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Palmer Dabbelt <palmer@...belt.com>
Cc:     guoren@...nel.org, Arnd Bergmann <arnd@...db.de>, heiko@...ech.de,
        linux-riscv@...ts.infradead.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, guoren@...ux.alibaba.com
Subject: Re: [PATCH] riscv: compat: Using seperated vdso_maps for
 compat_vdso_info

On 5/25/22 14:34, Palmer Dabbelt wrote:
> On Wed, 25 May 2022 14:15:03 PDT (-0700), linux@...ck-us.net wrote:
>> On 5/25/22 09:04, 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>
>>> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
>>> Signed-off-by: Guo Ren <guoren@...nel.org>
>>> Cc: Palmer Dabbelt <palmer@...belt.com>
>>> Cc: Heiko Stübner <heiko@...ech.de>
>>
>> Tested-by: Guenter Roeck <linux@...ck-us.net>
> 
> Sorry I'm a bit buried right now, this is fixing the issue you pointed out earlier?
> 
Yes.

Thanks,
Guenter

>>
>>> ---
>>>   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..69b05b6c181b 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   = "[vvar]",
>>> +        .fault = vvar_fault,
>>> +    },
>>> +    [RV_VDSO_MAP_VDSO] = {
>>> +        .name   = "[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
>>>