Re: [PATCH v7 16/25] arm: Add support for generic vDSO (causing crash)

[Philippe Mathieu-DaudÃ]

On Wed, Dec 4, 2019 at 6:23 PM Vincenzo Frascino
<vincenzo.frascino@xxxxxxx> wrote:
> On 12/4/19 4:16 PM, Guenter Roeck wrote:
[...]
> --->8---
>
> Author: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Date:   Wed Dec 4 16:58:55 2019 +0000
>
>     arm: Fix __arch_get_hw_counter() access to CNTVCT
>
>     __arch_get_hw_counter() should check clock_mode to see if it can access
>     CNTVCT. With the conversion to unified vDSO this check has been left out.
>
>     This causes on imx v6 and v7 (imx_v6_v7_defconfig) and other platforms to
>     hang at boot during the execution of the init process as per below:
>
>     [   19.976852] Run /sbin/init as init process
>     [   20.044931] Kernel panic - not syncing: Attempted to kill init!
>     exitcode=0x00000004
>
>     Fix the problem verifying that clock_mode is set coherently before
>     accessing CNTVCT.
>
>     Cc: Russell King <linux@xxxxxxxxxxxxxxx>
>     Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
>     Investigated-by: Arnd Bergmann <arnd@xxxxxxxx>

There are only 2 "Investigated-by" vs 7k+ "Suggested-by"... Is there a
real difference?

>     Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
>
> diff --git a/arch/arm/include/asm/vdso/gettimeofday.h
> b/arch/arm/include/asm/vdso/gettimeofday.h
> index 5b879ae7afc1..0ad2429c324f 100644
> --- a/arch/arm/include/asm/vdso/gettimeofday.h
> +++ b/arch/arm/include/asm/vdso/gettimeofday.h
> @@ -75,6 +75,9 @@ static __always_inline u64 __arch_get_hw_counter(int clock_mode)
>  #ifdef CONFIG_ARM_ARCH_TIMER
>         u64 cycle_now;
>
> +       if (!clock_mode)
> +               return -EINVAL;
> +

Reviewed-by: Philippe Mathieu-Daudà <f4bug@xxxxxxxxx>

>         isb();
>         cycle_now = read_sysreg(CNTVCT);
>
>