ALSA: Avoid using timespec for struct snd_pcm_status

The struct snd_pcm_status will use 'timespec' type variables to record
timestamp, which is not year 2038 safe on 32bits system.

Userspace will use SNDRV_PCM_IOCTL_STATUS and SNDRV_PCM_IOCTL_STATUS_EXT
as commands to issue ioctl() to fill the 'snd_pcm_status' structure in
userspace. The command number is always defined through _IOR/_IOW/IORW,
so when userspace changes the definition of 'struct timespec' to use
64-bit types, the command number also changes.

Thus in the kernel, we now need to define two versions of each such ioctl
and corresponding ioctl commands to handle 32bit time_t and 64bit time_t
in native mode:
struct snd_pcm_status32 {
	......

	s32 trigger_tstamp_sec;
	s32 trigger_tstamp_nsec;

	......

	s32 audio_tstamp_sec;
	s32 audio_tstamp_nsec;

	......
};

struct snd_pcm_status64 {
	......

	s32 trigger_tstamp_sec;
	s32 trigger_tstamp_nsec;

	......

	s32 audio_tstamp_sec;
	s32 audio_tstamp_nsec;

	......
};

Moreover in compat file, we renamed or introduced new structures to handle
32bit/64bit time_t in compatible mode. The 'struct snd_pcm_status32' and
snd_pcm_status_user32() are used to handle 32bit time_t in compat mode.
'struct compat_snd_pcm_status64' and snd_pcm_status_user_compat64() are used
to handle 64bit time_t.

The implicit padding before timespec is made explicit to avoid incompatible
structure layout between 32-bit and 64-bit x86 due to the different
alignment requirements, and the snd_pcm_status structure is now hidden
from the kernel to avoid relying on the timespec definitio definitionn

Finally we can replace SNDRV_PCM_IOCTL_STATUS and SNDRV_PCM_IOCTL_STATUS_EXT
with new commands and introduce new functions to fill new 'struct snd_pcm_status64'
instead of using unsafe 'struct snd_pcm_status'. Then in future, the new
commands can be matched when userspace changes 'timespec' to 64bit type
to make a size change of 'struct snd_pcm_status'. When glibc changes time_t
to 64-bit, any recompiled program will issue ioctl commands that the kernel
does not understand without this patch.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/sound/pcm.h

@@ -44,6 +44,7 @@ struct snd_pcm_hardware {
 	size_t fifo_size;		/* fifo size in bytes */
 };
 
+struct snd_pcm_status64;
 struct snd_pcm_substream;
 
 struct snd_pcm_audio_tstamp_config; /* definitions further down */
@@ -558,8 +559,8 @@ int snd_pcm_notify(struct snd_pcm_notify *notify, int nfree);
 int snd_pcm_info(struct snd_pcm_substream *substream, struct snd_pcm_info *info);
 int snd_pcm_info_user(struct snd_pcm_substream *substream,
 		      struct snd_pcm_info __user *info);
-int snd_pcm_status(struct snd_pcm_substream *substream,
-		   struct snd_pcm_status *status);
+int snd_pcm_status64(struct snd_pcm_substream *substream,
+		     struct snd_pcm_status64 *status);
 int snd_pcm_start(struct snd_pcm_substream *substream);
 int snd_pcm_stop(struct snd_pcm_substream *substream, snd_pcm_state_t status);
 int snd_pcm_drain_done(struct snd_pcm_substream *substream);
@@ -1422,4 +1423,55 @@ static inline u64 pcm_format_to_bits(snd_pcm_format_t pcm_format)
 #define pcm_dbg(pcm, fmt, args...) \
 	dev_dbg((pcm)->card->dev, fmt, ##args)
 
+struct snd_pcm_status64 {
+	snd_pcm_state_t state;		/* stream state */
+	u8 rsvd[4];
+	s64 trigger_tstamp_sec;		/* time when stream was started/stopped/paused */
+	s64 trigger_tstamp_nsec;
+	s64 tstamp_sec;			/* reference timestamp */
+	s64 tstamp_nsec;
+	snd_pcm_uframes_t appl_ptr;	/* appl ptr */
+	snd_pcm_uframes_t hw_ptr;	/* hw ptr */
+	snd_pcm_sframes_t delay;	/* current delay in frames */
+	snd_pcm_uframes_t avail;	/* number of frames available */
+	snd_pcm_uframes_t avail_max;	/* max frames available on hw since last status */
+	snd_pcm_uframes_t overrange;	/* count of ADC (capture) overrange detections from last status */
+	snd_pcm_state_t suspended_state; /* suspended stream state */
+	__u32 audio_tstamp_data;	 /* needed for 64-bit alignment, used for configs/report to/from userspace */
+	s64 audio_tstamp_sec;		/* sample counter, wall clock, PHC or on-demand sync'ed */
+	s64 audio_tstamp_nsec;
+	s64 driver_tstamp_sec;		/* useful in case reference system tstamp is reported with delay */
+	s64 driver_tstamp_nsec;
+	__u32 audio_tstamp_accuracy;	/* in ns units, only valid if indicated in audio_tstamp_data */
+	unsigned char reserved[52-4*sizeof(s64)]; /* must be filled with zero */
+};
+
+#define SNDRV_PCM_IOCTL_STATUS64	_IOR('A', 0x20, struct snd_pcm_status64)
+#define SNDRV_PCM_IOCTL_STATUS_EXT64	_IOWR('A', 0x24, struct snd_pcm_status64)
+
+struct snd_pcm_status32 {
+	s32 state;		/* stream state */
+	s32 trigger_tstamp_sec;	/* time when stream was started/stopped/paused */
+	s32 trigger_tstamp_nsec;
+	s32 tstamp_sec;		/* reference timestamp */
+	s32 tstamp_nsec;
+	u32 appl_ptr;		/* appl ptr */
+	u32 hw_ptr;		/* hw ptr */
+	s32 delay;		/* current delay in frames */
+	u32 avail;		/* number of frames available */
+	u32 avail_max;		/* max frames available on hw since last status */
+	u32 overrange;		/* count of ADC (capture) overrange detections from last status */
+	s32 suspended_state;	/* suspended stream state */
+	u32 audio_tstamp_data;	/* needed for 64-bit alignment, used for configs/report to/from userspace */
+	s32 audio_tstamp_sec;	/* sample counter, wall clock, PHC or on-demand sync'ed */
+	s32 audio_tstamp_nsec;
+	s32 driver_tstamp_sec;	/* useful in case reference system tstamp is reported with delay */
+	s32 driver_tstamp_nsec;
+	u32 audio_tstamp_accuracy;	/* in ns units, only valid if indicated in audio_tstamp_data */
+	unsigned char reserved[52-4*sizeof(s32)]; /* must be filled with zero */
+};
+
+#define SNDRV_PCM_IOCTL_STATUS32	_IOR('A', 0x20, struct snd_pcm_status32)
+#define SNDRV_PCM_IOCTL_STATUS_EXT32	_IOWR('A', 0x24, struct snd_pcm_status32)
+
 #endif /* __SOUND_PCM_H */