From patchwork Wed Oct 11 15:20:12 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 9999917 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8A4136037F for ; Wed, 11 Oct 2017 15:21:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 71C5228A83 for ; Wed, 11 Oct 2017 15:21:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6681B28A86; Wed, 11 Oct 2017 15:21:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RCVD_IN_SORBS_SPAM autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5CE2D28A85 for ; Wed, 11 Oct 2017 15:21:26 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 619606E0BF; Wed, 11 Oct 2017 15:21:25 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mout.kundenserver.de (mout.kundenserver.de [212.227.126.135]) by gabe.freedesktop.org (Postfix) with ESMTPS id 062D26E0BF for ; Wed, 11 Oct 2017 15:21:23 +0000 (UTC) Received: from wuerfel.lan ([95.208.190.237]) by mrelayeu.kundenserver.de (mreue005 [212.227.15.129]) with ESMTPA (Nemesis) id 0Lu05i-1dIoti2eM2-011V4D; Wed, 11 Oct 2017 17:21:04 +0200 From: Arnd Bergmann To: Daniel Vetter , Daniel Vetter , Jani Nikula , Sean Paul , David Airlie Subject: [PATCH 1/2] drm: vblank: use ktime_t instead of timeval Date: Wed, 11 Oct 2017 17:20:12 +0200 Message-Id: <20171011152059.2394516-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K0:SwuMn8aOZd3i87BZeHwlObDWhw7Z61RUiQ4LpVappN42PpYYx55 JqXH+Hmdz1Ox9gJqNtoQqtoMpwawkDlkF3u8CkeG96xUhnbnnvZn+zznCnuf3q0Mo4ca/Ht AofSM9FALn+z9+LTytC5ZnjkWtJlWh3vuAjRigBaxAhRuDFJ0PszBp/7qSZOD1A77tBrHPf K76U9vx0MlFJOg5o6AKNA== X-UI-Out-Filterresults: notjunk:1; V01:K0:H0foQYNL+a4=:GnApkOPivajR5UR8bpIJcs kW/w7VF4C6kIY/hY8sIUiDFIFkmSbgoM4M3oPUJTaBMmyjKe8gk3GvIQ//EWSojuBQ7NlcC3Z 9bTzxGC8C8IKsvtiGHCjeQxdxegnb7eFSLG2zdkOxfrOnWJSJXTIn7bbD37eEQENll257vcbt EsitNeaRITsAbOr0fM5ZhpCVl2JYNNarBDBWrS9ASuT8DLlQ9oXlyWgwes6R2IOD1dGsA2dHz 820DuU/caLsXmJ60L5t787l4+BA2RqaBkDcx0gYVp7Fj6pDJMK4OLNWsYWZ09gFkMkPnUPJqQ O5s9czPRiMUs9/6eNn60xIEX38CuPVAFRPS3VGNtEwPWIO/v9h2rzHnBGif30XSRDw3AIs91n 2tyVaNjYBcM1xh62EEVi4emPtVDpQ3NvLYUnpN07E96CUuTO+vRCJ6haMI/5rMJ6LRQqSimjo PPMQTyog2EMntYaRewXzEXjIfwibc4bXssJAQj7rA2INXLvEKpr8SuaVvvsGJFA4ehcg4AAgl 7877DCdYTSmdKSsb6OvE7xUtWV1bYkvhxmmekMKYkkT623eOJTTHx2NIIiSh7lR28dxPh6uvR o8oOkYHkw4QdiuH9n/y+2/p9MGWNC/Jei2CtlxdgvHYvNpqfU5BD717FF2EkJTjSHIFWpo68x q0e55kMQuYAOmVY79eBgPaoCY1TM7wCQzQXg2yZCIXTBqsubfLROe/TyzcTegueIkWPquOQLv CEaQ6T/irOiQyI0Y6OEPByCI0bxbGwmhPGUOZg== Cc: Arnd Bergmann , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Alex Deucher , Thierry Reding X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP The drm vblank handling uses 'timeval' to store timestamps in either monotonic or wall-clock time base. In either case, it reads the current time as a ktime_t in get_drm_timestamp() and converts it from there. This is a bit suspicious, as users of 'timeval' often suffer from the time_t overflow in y2038. I have gone through this code and found that it is unlikely to cause problems here: - The user space ABI does not use time_t or timeval, but uses 'u32' and 'long' as the types. This means at least that rebuilding user programs against a new libc with 64-bit time_t does not change the ABI. - As of commit c61eef726a78 ("drm: add support for monotonic vblank timestamps") in linux-3.8, the monotonic timestamp is the default and can only get reverted to wall-clock through a module-parameter. - With the default monotonic timestamps, there is no problem at all. - The drm_wait_vblank_ioctl() interface is alway safe on 64-bit architectures, on 32-bit it might overflow the 'long' timestamps in 2038 with wall-clock timestamps. - The event handling uses 'u32' seconds, which overflow in 2106 on both 32-bit and 64-bit machines, when wall-clock timestamps are used. - The effect of overflowing either of the two is only temporary (during the overflow, and is likely to keep working again afterwards. It is likely the same problem as observing a 'settimeofday()' call, which was the reason for moving to the monotonic timestamps in the first place. Overall, this seems good enough, so my patch removes the use of 'timeval' from the vblank handling altogether and uses ktime_t consistently, except for the part where we copy the data to user space structures in the existing format. Signed-off-by: Arnd Bergmann Reviewed-by: Sean Paul Reviewed-by: Keith Packard --- drivers/gpu/drm/drm_vblank.c | 123 +++++++++++++++++++++++-------------------- include/drm/drm_drv.h | 2 +- include/drm/drm_vblank.h | 6 +-- 3 files changed, 71 insertions(+), 60 deletions(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 70f2b9593edc..c605c3ad6b6e 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -78,7 +78,7 @@ static bool drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe, - struct timeval *tvblank, bool in_vblank_irq); + ktime_t *tvblank, bool in_vblank_irq); static unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */ @@ -99,7 +99,7 @@ MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps"); static void store_vblank(struct drm_device *dev, unsigned int pipe, u32 vblank_count_inc, - struct timeval *t_vblank, u32 last) + ktime_t t_vblank, u32 last) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; @@ -108,7 +108,7 @@ static void store_vblank(struct drm_device *dev, unsigned int pipe, vblank->last = last; write_seqlock(&vblank->seqlock); - vblank->time = *t_vblank; + vblank->time = t_vblank; vblank->count += vblank_count_inc; write_sequnlock(&vblank->seqlock); } @@ -151,7 +151,7 @@ static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe { u32 cur_vblank; bool rc; - struct timeval t_vblank; + ktime_t t_vblank; int count = DRM_TIMESTAMP_MAXRETRIES; spin_lock(&dev->vblank_time_lock); @@ -171,13 +171,13 @@ static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe * interrupt and assign 0 for now, to mark the vblanktimestamp as invalid. */ if (!rc) - t_vblank = (struct timeval) {0, 0}; + t_vblank = 0; /* * +1 to make sure user will never see the same * vblank counter value before and after a modeset */ - store_vblank(dev, pipe, 1, &t_vblank, cur_vblank); + store_vblank(dev, pipe, 1, t_vblank, cur_vblank); spin_unlock(&dev->vblank_time_lock); } @@ -200,7 +200,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; u32 cur_vblank, diff; bool rc; - struct timeval t_vblank; + ktime_t t_vblank; int count = DRM_TIMESTAMP_MAXRETRIES; int framedur_ns = vblank->framedur_ns; @@ -225,11 +225,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, /* trust the hw counter when it's around */ diff = (cur_vblank - vblank->last) & dev->max_vblank_count; } else if (rc && framedur_ns) { - const struct timeval *t_old; - u64 diff_ns; - - t_old = &vblank->time; - diff_ns = timeval_to_ns(&t_vblank) - timeval_to_ns(t_old); + u64 diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time)); /* * Figure out how many vblanks we've missed based @@ -278,9 +274,9 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, * for now, to mark the vblanktimestamp as invalid. */ if (!rc && !in_vblank_irq) - t_vblank = (struct timeval) {0, 0}; + t_vblank = 0; - store_vblank(dev, pipe, diff, &t_vblank, cur_vblank); + store_vblank(dev, pipe, diff, t_vblank, cur_vblank); } static u32 drm_vblank_count(struct drm_device *dev, unsigned int pipe) @@ -556,7 +552,7 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants); * @pipe: index of CRTC whose vblank timestamp to retrieve * @max_error: Desired maximum allowable error in timestamps (nanosecs) * On return contains true maximum error of timestamp - * @vblank_time: Pointer to struct timeval which should receive the timestamp + * @vblank_time: Pointer to time which should receive the timestamp * @in_vblank_irq: * True when called from drm_crtc_handle_vblank(). Some drivers * need to apply some workarounds for gpu-specific vblank irq quirks @@ -584,10 +580,10 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants); bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, unsigned int pipe, int *max_error, - struct timeval *vblank_time, + ktime_t *vblank_time, bool in_vblank_irq) { - struct timeval tv_etime; + struct timespec64 ts_etime, ts_vblank_time; ktime_t stime, etime; bool vbl_status; struct drm_crtc *crtc; @@ -680,29 +676,27 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, etime = ktime_mono_to_real(etime); /* save this only for debugging purposes */ - tv_etime = ktime_to_timeval(etime); + ts_etime = ktime_to_timespec64(etime); + ts_vblank_time = ktime_to_timespec64(*vblank_time); /* Subtract time delta from raw timestamp to get final * vblank_time timestamp for end of vblank. */ etime = ktime_sub_ns(etime, delta_ns); - *vblank_time = ktime_to_timeval(etime); + *vblank_time = etime; - DRM_DEBUG_VBL("crtc %u : v p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n", + DRM_DEBUG_VBL("crtc %u : v p(%d,%d)@ %lld.%06ld -> %lld.%06ld [e %d us, %d rep]\n", pipe, hpos, vpos, - (long)tv_etime.tv_sec, (long)tv_etime.tv_usec, - (long)vblank_time->tv_sec, (long)vblank_time->tv_usec, - duration_ns/1000, i); + (u64)ts_etime.tv_sec, ts_etime.tv_nsec / 1000, + (u64)ts_vblank_time.tv_sec, ts_vblank_time.tv_nsec / 1000, + duration_ns / 1000, i); return true; } EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos); -static struct timeval get_drm_timestamp(void) +static ktime_t get_drm_timestamp(void) { - ktime_t now; - - now = drm_timestamp_monotonic ? ktime_get() : ktime_get_real(); - return ktime_to_timeval(now); + return drm_timestamp_monotonic ? ktime_get() : ktime_get_real(); } /** @@ -710,7 +704,7 @@ static struct timeval get_drm_timestamp(void) * vblank interval * @dev: DRM device * @pipe: index of CRTC whose vblank timestamp to retrieve - * @tvblank: Pointer to target struct timeval which should receive the timestamp + * @tvblank: Pointer to target time which should receive the timestamp * @in_vblank_irq: * True when called from drm_crtc_handle_vblank(). Some drivers * need to apply some workarounds for gpu-specific vblank irq quirks @@ -728,7 +722,7 @@ static struct timeval get_drm_timestamp(void) */ static bool drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe, - struct timeval *tvblank, bool in_vblank_irq) + ktime_t *tvblank, bool in_vblank_irq) { bool ret = false; @@ -769,14 +763,14 @@ u32 drm_crtc_vblank_count(struct drm_crtc *crtc) EXPORT_SYMBOL(drm_crtc_vblank_count); static u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, - struct timeval *vblanktime) + ktime_t *vblanktime) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; u32 vblank_count; unsigned int seq; if (WARN_ON(pipe >= dev->num_crtcs)) { - *vblanktime = (struct timeval) { 0 }; + *vblanktime = 0; return 0; } @@ -793,7 +787,7 @@ static u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, * drm_crtc_vblank_count_and_time - retrieve "cooked" vblank counter value * and the system timestamp corresponding to that vblank counter value * @crtc: which counter to retrieve - * @vblanktime: Pointer to struct timeval to receive the vblank timestamp. + * @vblanktime: Pointer to time to receive the vblank timestamp. * * Fetches the "cooked" vblank count value that represents the number of * vblank events since the system was booted, including lost events due to @@ -801,7 +795,7 @@ static u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, * of the vblank interval that corresponds to the current vblank counter value. */ u32 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, - struct timeval *vblanktime) + ktime_t *vblanktime) { return drm_vblank_count_and_time(crtc->dev, drm_crtc_index(crtc), vblanktime); @@ -810,11 +804,18 @@ EXPORT_SYMBOL(drm_crtc_vblank_count_and_time); static void send_vblank_event(struct drm_device *dev, struct drm_pending_vblank_event *e, - unsigned long seq, struct timeval *now) + unsigned long seq, ktime_t now) { + struct timespec64 tv = ktime_to_timespec64(now); + e->event.sequence = seq; - e->event.tv_sec = now->tv_sec; - e->event.tv_usec = now->tv_usec; + /* + * e->event is a user space structure, with hardcoded unsigned + * 32-bit seconds/microseconds. This will overflow in 2106 for + * drm_timestamp_monotonic==0, but not with drm_timestamp_monotonic==1 + */ + e->event.tv_sec = tv.tv_sec; + e->event.tv_usec = tv.tv_nsec / 1000; trace_drm_vblank_event_delivered(e->base.file_priv, e->pipe, e->event.sequence); @@ -891,7 +892,7 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc, { struct drm_device *dev = crtc->dev; unsigned int seq, pipe = drm_crtc_index(crtc); - struct timeval now; + ktime_t now; if (dev->num_crtcs > 0) { seq = drm_vblank_count_and_time(dev, pipe, &now); @@ -902,7 +903,7 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc, } e->pipe = pipe; e->event.crtc_id = crtc->base.id; - send_vblank_event(dev, e, seq, &now); + send_vblank_event(dev, e, seq, now); } EXPORT_SYMBOL(drm_crtc_send_vblank_event); @@ -1100,7 +1101,8 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc) unsigned int pipe = drm_crtc_index(crtc); struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; struct drm_pending_vblank_event *e, *t; - struct timeval now; + + ktime_t now; unsigned long irqflags; unsigned int seq; @@ -1141,7 +1143,7 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc) e->event.sequence, seq); list_del(&e->base.link); drm_vblank_put(dev, pipe); - send_vblank_event(dev, e, seq, &now); + send_vblank_event(dev, e, seq, now); } spin_unlock_irqrestore(&dev->event_lock, irqflags); @@ -1321,7 +1323,7 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe, { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; struct drm_pending_vblank_event *e; - struct timeval now; + ktime_t now; unsigned long flags; unsigned int seq; int ret; @@ -1367,7 +1369,7 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe, e->event.sequence = vblwait->request.sequence; if (vblank_passed(seq, vblwait->request.sequence)) { drm_vblank_put(dev, pipe); - send_vblank_event(dev, e, seq, &now); + send_vblank_event(dev, e, seq, now); vblwait->reply.sequence = seq; } else { /* drm_handle_vblank_events will call drm_vblank_put */ @@ -1398,6 +1400,24 @@ static bool drm_wait_vblank_is_query(union drm_wait_vblank *vblwait) _DRM_VBLANK_NEXTONMISS)); } +static void drm_wait_vblank_reply(struct drm_device *dev, unsigned int pipe, + struct drm_wait_vblank_reply *reply) +{ + ktime_t now; + struct timespec64 ts; + + /* + * drm_wait_vblank_reply is a UAPI structure that uses 'long' + * to store the seconds. This will overflow in y2038 on 32-bit + * architectures with drm_timestamp_monotonic==0, but not with + * drm_timestamp_monotonic==1 (the default). + */ + reply->sequence = drm_vblank_count_and_time(dev, pipe, &now); + ts = ktime_to_timespec64(now); + reply->tval_sec = (u32)ts.tv_sec; + reply->tval_usec = ts.tv_nsec / 1000; +} + int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { @@ -1439,12 +1459,7 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, if (dev->vblank_disable_immediate && drm_wait_vblank_is_query(vblwait) && READ_ONCE(vblank->enabled)) { - struct timeval now; - - vblwait->reply.sequence = - drm_vblank_count_and_time(dev, pipe, &now); - vblwait->reply.tval_sec = now.tv_sec; - vblwait->reply.tval_usec = now.tv_usec; + drm_wait_vblank_reply(dev, pipe, &vblwait->reply); return 0; } @@ -1487,11 +1502,7 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, } if (ret != -EINTR) { - struct timeval now; - - vblwait->reply.sequence = drm_vblank_count_and_time(dev, pipe, &now); - vblwait->reply.tval_sec = now.tv_sec; - vblwait->reply.tval_usec = now.tv_usec; + drm_wait_vblank_reply(dev, pipe, &vblwait->reply); DRM_DEBUG("crtc %d returning %u to client\n", pipe, vblwait->reply.sequence); @@ -1507,7 +1518,7 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe) { struct drm_pending_vblank_event *e, *t; - struct timeval now; + ktime_t now; unsigned int seq; assert_spin_locked(&dev->event_lock); @@ -1525,7 +1536,7 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe) list_del(&e->base.link); drm_vblank_put(dev, pipe); - send_vblank_event(dev, e, seq, &now); + send_vblank_event(dev, e, seq, now); } trace_drm_vblank_event(pipe, seq); diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h index ee06ecd6c01f..412e83a4d3db 100644 --- a/include/drm/drm_drv.h +++ b/include/drm/drm_drv.h @@ -324,7 +324,7 @@ struct drm_driver { */ bool (*get_vblank_timestamp) (struct drm_device *dev, unsigned int pipe, int *max_error, - struct timeval *vblank_time, + ktime_t *vblank_time, bool in_vblank_irq); /** diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index 7fba9efe4951..6a58e2e91a0f 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -92,7 +92,7 @@ struct drm_vblank_crtc { /** * @time: Vblank timestamp corresponding to @count. */ - struct timeval time; + ktime_t time; /** * @refcount: Number of users/waiters of the vblank interrupt. Only when @@ -154,7 +154,7 @@ struct drm_vblank_crtc { int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs); u32 drm_crtc_vblank_count(struct drm_crtc *crtc); u32 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, - struct timeval *vblanktime); + ktime_t *vblanktime); void drm_crtc_send_vblank_event(struct drm_crtc *crtc, struct drm_pending_vblank_event *e); void drm_crtc_arm_vblank_event(struct drm_crtc *crtc, @@ -172,7 +172,7 @@ u32 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc); bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, unsigned int pipe, int *max_error, - struct timeval *vblank_time, + ktime_t *vblank_time, bool in_vblank_irq); void drm_calc_timestamping_constants(struct drm_crtc *crtc, const struct drm_display_mode *mode);