On Mon, Feb 02, 2015 at 05:36:33PM +0000, Mark Rutland wrote:
> From: Catalin Marinas <catalin.marinas@xxxxxxx>
>
> Commit 0b46b8a718c6 got back-ported to stable, but the later fix in commit
> d6ad36913083d683 didn't as it wasn't appropriately Cc'd. This has left arm64
> broken in stable when booted at EL2:
>
> BUG: failure at ./arch/arm64/include/asm/arch_timer.h:112/arch_counter_get_cntpct()!
>
Looks like the 3.16 kernel is also affected, as it includes a backport
of commit 0b46b8a718c6. I'll queue this for the 3.16 kernel as well.
Cheers,
--
Luís
> Mark.
>
> ---->8----
> Commit d6ad36913083d683aad4e02e53580c995f1a6ede upstream.
>
> Commit 0b46b8a718c6 (clocksource: arch_timer: Fix code to use physical
> timers when requested) introduces the use of physical counters in the
> ARM architected timer driver. However, he arm64 kernel uses CNTVCT in
> VDSO. When booting in EL2, the kernel switches to the physical timers to
> make things easier for KVM but it continues to use the virtual counter
> both in user and kernel. While in such scenario CNTVCT == CNTPCT (since
> CNTVOFF is initialised by the kernel to 0), we want to spot firmware
> bugs corrupting CNTVOFF early (which would affect CNTVCT).
>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Tested-by: Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>
> Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> Fixes: 0b46b8a718c6 ("clocksource: arch_timer: Fix code to use physical timers when requested")
> Cc: Ian Campbell <ijc@xxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 3.18.x
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> ---
> drivers/clocksource/arm_arch_timer.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 1fa2af9..84b4c8b 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -462,7 +462,7 @@ static void __init arch_counter_register(unsigned type)
>
> /* Register the CP15 based counter if we have one */
> if (type & ARCH_CP15_TIMER) {
> - if (arch_timer_use_virtual)
> + if (IS_ENABLED(CONFIG_ARM64) || arch_timer_use_virtual)
> arch_timer_read_counter = arch_counter_get_cntvct;
> else
> arch_timer_read_counter = arch_counter_get_cntpct;
> --
> 1.9.1
>
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