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

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Message-ID: <a0bffec3-cf43-417e-3804-9248325266c3@roeck-us.net>
Date:   Wed, 25 May 2022 14:15:03 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     guoren@...nel.org, palmer@...osinc.com, arnd@...db.de,
        palmer@...belt.com, heiko@...ech.de
Cc:     linux-riscv@...ts.infradead.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH] riscv: compat: Using seperated vdso_maps for
 compat_vdso_info

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>

> ---
>   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
>