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Date:   Fri, 17 Jan 2020 16:47:26 +0100
From:   Guido =?iso-8859-1?Q?G=FCnther?= <agx@sigxcpu.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     y2038@lists.linaro.org, linux-kernel@vger.kernel.org,
        Lucas Stach <l.stach@pengutronix.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, etnaviv@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org,
        Christian Gmeiner <christian.gmeiner@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Russell King <linux+etnaviv@armlinux.org.uk>,
        Sam Ravnborg <sam@ravnborg.org>,
        Emil Velikov <emil.velikov@collabora.com>
Subject: Re: [PATCH v2 13/24] drm/etnaviv: reject timeouts with tv_nsec >=
 NSEC_PER_SEC
Message-ID: <20200117154726.GA328525@bogon.m.sigxcpu.org>
References: <20191213204936.3643476-1-arnd@arndb.de>
 <20191213205417.3871055-4-arnd@arndb.de>
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Hi,
On Fri, Dec 13, 2019 at 09:53:41PM +0100, Arnd Bergmann wrote:
> Most kernel interfaces that take a timespec require normalized
> representation with tv_nsec between 0 and NSEC_PER_SEC.
> 
> Passing values larger than 0x100000000ull further behaves differently
> on 32-bit and 64-bit kernels, and can cause the latter to spend a long
> time counting seconds in timespec64_sub()/set_normalized_timespec64().
> 
> Reject those large values at the user interface to enforce sane and
> portable behavior.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_drv.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> index 1f9c01be40d7..95d72dc00280 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> @@ -297,6 +297,9 @@ static int etnaviv_ioctl_gem_cpu_prep(struct drm_device *dev, void *data,
>  	if (args->op & ~(ETNA_PREP_READ | ETNA_PREP_WRITE | ETNA_PREP_NOSYNC))
>  		return -EINVAL;
>  
> +	if (args->timeout.tv_nsec > NSEC_PER_SEC)
> +		return -EINVAL;
> +
>  	obj = drm_gem_object_lookup(file, args->handle);
>  	if (!obj)
>  		return -ENOENT;
> @@ -360,6 +363,9 @@ static int etnaviv_ioctl_wait_fence(struct drm_device *dev, void *data,
>  	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
>  		return -EINVAL;
>  
> +	if (args->timeout.tv_nsec > NSEC_PER_SEC)
> +		return -EINVAL;
> +
>  	if (args->pipe >= ETNA_MAX_PIPES)
>  		return -EINVAL;
>  
> @@ -411,6 +417,9 @@ static int etnaviv_ioctl_gem_wait(struct drm_device *dev, void *data,
>  	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
>  		return -EINVAL;
>  
> +	if (args->timeout.tv_nsec > NSEC_PER_SEC)
> +		return -EINVAL;
> +
>  	if (args->pipe >= ETNA_MAX_PIPES)
>  		return -EINVAL;
>

This breaks rendering here on arm64/gc7000 due to

ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0

This is due to

    get_abs_timeout(&req.timeout, 5000000000);

in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.

Should i send a patch to revert that change since it breaks existing userspace?

Cheers,
 -- Guido

> -- 
> 2.20.0
> 
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> etnaviv@lists.freedesktop.org
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