[PATCH v2 2/2] rtc: move compat_ioctl handling into rtc-dev.c

[PATCH v2 2/2] rtc: move compat_ioctl handling into rtc-dev.c

[Arnd Bergmann]

We no longer need the rtc compat handling to be in common code, now that
all drivers are either moved to the rtc-class framework, or (rarely)
exist in drivers/char for architectures without compat mode (m68k,
alpha and ia64, respectively).

I checked the list of ioctl commands in drivers, and the ones that are
not already handled are all compatible, again with the one exception of
m68k driver, which implements RTC_PLL_GET and RTC_PLL_SET, but has no
compat mode.

Since the ioctl commands are either compatible or differ in both structure
and command code between 32-bit and 64-bit, we can merge the compat
handler into the native one and just implement the two common compat
commands (RTC_IRQP_READ, RTC_IRQP_SET) there.

The old conversion handler also deals with RTC_EPOCH_READ and
RTC_EPOCH_SET, which are not handled in rtc-dev.c but only in
a single device driver (rtc-vr41xx), so I'm adding the compat
version in the same place. I don't expect other drivers to need
those commands in the future.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: merge compat handler into ioctl function to avoid the
    compat_alloc_user_space() roundtrip, based on feedback
    from Al Viro.
---
 drivers/rtc/rtc-dev.c    | 13 +++++++++-
 drivers/rtc/rtc-vr41xx.c | 10 ++++++++
 fs/compat_ioctl.c        | 53 ----------------------------------------
 3 files changed, 22 insertions(+), 54 deletions(-)

diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 43d962a9c210..7c93dc6ec629 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -13,6 +13,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/compat.h>
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/sched/signal.h>
@@ -364,10 +365,19 @@ static long rtc_dev_ioctl(struct file *file,
 		mutex_unlock(&rtc->ops_lock);
 		return rtc_update_irq_enable(rtc, 0);
 
+#ifdef CONFIG_COMPAT
+#define RTC_IRQP_SET32		_IOW('p', 0x0c, compat_ulong_t)
+#define RTC_IRQP_READ32		_IOR('p', 0x0b, compat_ulong_t)
+	case RTC_IRQP_SET32:
+		err = rtc_irq_set_freq(rtc, arg);
+		break;
+	case RTC_IRQP_READ32:
+		err = put_user(rtc->irq_freq, (unsigned int __user *)uarg);
+		break;
+#endif
 	case RTC_IRQP_SET:
 		err = rtc_irq_set_freq(rtc, arg);
 		break;
-
 	case RTC_IRQP_READ:
 		err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 		break;
@@ -439,6 +449,7 @@ static const struct file_operations rtc_dev_fops = {
 	.read		= rtc_dev_read,
 	.poll		= rtc_dev_poll,
 	.unlocked_ioctl	= rtc_dev_ioctl,
+	.compat_ioctl	= rtc_dev_ioctl,
 	.open		= rtc_dev_open,
 	.release	= rtc_dev_release,
 	.fasync		= rtc_dev_fasync,
diff --git a/drivers/rtc/rtc-vr41xx.c b/drivers/rtc/rtc-vr41xx.c
index 70f013e692b0..1d90bde59d21 100644
--- a/drivers/rtc/rtc-vr41xx.c
+++ b/drivers/rtc/rtc-vr41xx.c
@@ -17,6 +17,7 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
+#include <linux/compat.h>
 #include <linux/err.h>
 #include <linux/fs.h>
 #include <linux/init.h>
@@ -79,6 +80,10 @@ static void __iomem *rtc2_base;
 #define rtc2_read(offset)		readw(rtc2_base + (offset))
 #define rtc2_write(offset, value)	writew((value), rtc2_base + (offset))
 
+/* 32-bit compat for ioctls that nobody else uses */
+#define RTC_EPOCH_READ32	_IOR('p', 0x0d, compat_ulong_t)
+#define RTC_EPOCH_SET32		_IOW('p', 0x0e, compat_ulong_t)
+
 static unsigned long epoch = 1970;	/* Jan 1 1970 00:00:00 */
 
 static DEFINE_SPINLOCK(rtc_lock);
@@ -195,6 +200,11 @@ static int vr41xx_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long
 	switch (cmd) {
 	case RTC_EPOCH_READ:
 		return put_user(epoch, (unsigned long __user *)arg);
+#ifdef CONFIG_COMPAT
+	case RTC_EPOCH_READ32:
+		return put_user(epoch, (unsigned int __user *)arg);
+	case RTC_EPOCH_SET32:
+#endif
 	case RTC_EPOCH_SET:
 		/* Doesn't support before 1900 */
 		if (arg < 1900)
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 5c37104b8805..9237076bdcf5 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -46,7 +46,6 @@
 #include <linux/raw.h>
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
-#include <linux/rtc.h>
 #include <linux/pci.h>
 #include <linux/serial.h>
 #include <linux/if_tun.h>
@@ -426,37 +425,6 @@ static int serial_struct_ioctl(struct file *file,
         return err;
 }
 
-#define RTC_IRQP_READ32		_IOR('p', 0x0b, compat_ulong_t)
-#define RTC_IRQP_SET32		_IOW('p', 0x0c, compat_ulong_t)
-#define RTC_EPOCH_READ32	_IOR('p', 0x0d, compat_ulong_t)
-#define RTC_EPOCH_SET32		_IOW('p', 0x0e, compat_ulong_t)
-
-static int rtc_ioctl(struct file *file,
-		unsigned cmd, void __user *argp)
-{
-	unsigned long __user *valp = compat_alloc_user_space(sizeof(*valp));
-	int ret;
-
-	if (valp == NULL)
-		return -EFAULT;
-	switch (cmd) {
-	case RTC_IRQP_READ32:
-	case RTC_EPOCH_READ32:
-		ret = do_ioctl(file, (cmd == RTC_IRQP_READ32) ?
-					RTC_IRQP_READ : RTC_EPOCH_READ,
-					(unsigned long)valp);
-		if (ret)
-			return ret;
-		return convert_in_user(valp, (unsigned int __user *)argp);
-	case RTC_IRQP_SET32:
-		return do_ioctl(file, RTC_IRQP_SET, (unsigned long)argp);
-	case RTC_EPOCH_SET32:
-		return do_ioctl(file, RTC_EPOCH_SET, (unsigned long)argp);
-	}
-
-	return -ENOIOCTLCMD;
-}
-
 /* on ia32 l_start is on a 32-bit boundary */
 #if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
 struct space_resv_32 {
@@ -609,21 +577,6 @@ COMPATIBLE_IOCTL(SCSI_IOCTL_GET_PCI)
 /* Big V (don't complain on serial console) */
 IGNORE_IOCTL(VT_OPENQRY)
 IGNORE_IOCTL(VT_GETMODE)
-/* Little p (/dev/rtc, /dev/envctrl, etc.) */
-COMPATIBLE_IOCTL(RTC_AIE_ON)
-COMPATIBLE_IOCTL(RTC_AIE_OFF)
-COMPATIBLE_IOCTL(RTC_UIE_ON)
-COMPATIBLE_IOCTL(RTC_UIE_OFF)
-COMPATIBLE_IOCTL(RTC_PIE_ON)
-COMPATIBLE_IOCTL(RTC_PIE_OFF)
-COMPATIBLE_IOCTL(RTC_WIE_ON)
-COMPATIBLE_IOCTL(RTC_WIE_OFF)
-COMPATIBLE_IOCTL(RTC_ALM_SET)
-COMPATIBLE_IOCTL(RTC_ALM_READ)
-COMPATIBLE_IOCTL(RTC_RD_TIME)
-COMPATIBLE_IOCTL(RTC_SET_TIME)
-COMPATIBLE_IOCTL(RTC_WKALM_SET)
-COMPATIBLE_IOCTL(RTC_WKALM_RD)
 /*
  * These two are only for the sbus rtc driver, but
  * hwclock tries them on every rtc device first when
@@ -1005,12 +958,6 @@ static long do_ioctl_trans(unsigned int cmd,
 	case TIOCGSERIAL:
 	case TIOCSSERIAL:
 		return serial_struct_ioctl(file, cmd, argp);
-	/* Not implemented in the native kernel */
-	case RTC_IRQP_READ32:
-	case RTC_IRQP_SET32:
-	case RTC_EPOCH_READ32:
-	case RTC_EPOCH_SET32:
-		return rtc_ioctl(file, cmd, argp);
 	}
 
 	/*
-- 
2.18.0

Re: [PATCH v2 2/2] rtc: move compat_ioctl handling into rtc-dev.c

[Alexandre Belloni]

Hi Arnd,

On 28/08/2018 16:26:31+0200, Arnd Bergmann wrote:
> We no longer need the rtc compat handling to be in common code, now that
> all drivers are either moved to the rtc-class framework, or (rarely)
> exist in drivers/char for architectures without compat mode (m68k,
> alpha and ia64, respectively).
> 
> I checked the list of ioctl commands in drivers, and the ones that are
> not already handled are all compatible, again with the one exception of
> m68k driver, which implements RTC_PLL_GET and RTC_PLL_SET, but has no
> compat mode.
> 
> Since the ioctl commands are either compatible or differ in both structure
> and command code between 32-bit and 64-bit, we can merge the compat
> handler into the native one and just implement the two common compat
> commands (RTC_IRQP_READ, RTC_IRQP_SET) there.
> 
> The old conversion handler also deals with RTC_EPOCH_READ and
> RTC_EPOCH_SET, which are not handled in rtc-dev.c but only in
> a single device driver (rtc-vr41xx), so I'm adding the compat
> version in the same place. I don't expect other drivers to need
> those commands in the future.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: merge compat handler into ioctl function to avoid the
>     compat_alloc_user_space() roundtrip, based on feedback
>     from Al Viro.
> ---
>  drivers/rtc/rtc-dev.c    | 13 +++++++++-
>  drivers/rtc/rtc-vr41xx.c | 10 ++++++++
>  fs/compat_ioctl.c        | 53 ----------------------------------------
>  3 files changed, 22 insertions(+), 54 deletions(-)
> 

This doesn't apply on v4.19-rc1, can you rebase?

> diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
> index 43d962a9c210..7c93dc6ec629 100644
> --- a/drivers/rtc/rtc-dev.c
> +++ b/drivers/rtc/rtc-dev.c
> @@ -13,6 +13,7 @@
>  
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
> +#include <linux/compat.h>
>  #include <linux/module.h>
>  #include <linux/rtc.h>
>  #include <linux/sched/signal.h>
> @@ -364,10 +365,19 @@ static long rtc_dev_ioctl(struct file *file,
>  		mutex_unlock(&rtc->ops_lock);
>  		return rtc_update_irq_enable(rtc, 0);
>  
> +#ifdef CONFIG_COMPAT
> +#define RTC_IRQP_SET32		_IOW('p', 0x0c, compat_ulong_t)
> +#define RTC_IRQP_READ32		_IOR('p', 0x0b, compat_ulong_t)
> +	case RTC_IRQP_SET32:
> +		err = rtc_irq_set_freq(rtc, arg);
> +		break;
> +	case RTC_IRQP_READ32:
> +		err = put_user(rtc->irq_freq, (unsigned int __user *)uarg);
> +		break;
> +#endif
>  	case RTC_IRQP_SET:
>  		err = rtc_irq_set_freq(rtc, arg);
>  		break;
> -
>  	case RTC_IRQP_READ:
>  		err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
>  		break;
> @@ -439,6 +449,7 @@ static const struct file_operations rtc_dev_fops = {
>  	.read		= rtc_dev_read,
>  	.poll		= rtc_dev_poll,
>  	.unlocked_ioctl	= rtc_dev_ioctl,
> +	.compat_ioctl	= rtc_dev_ioctl,
>  	.open		= rtc_dev_open,
>  	.release	= rtc_dev_release,
>  	.fasync		= rtc_dev_fasync,
> diff --git a/drivers/rtc/rtc-vr41xx.c b/drivers/rtc/rtc-vr41xx.c
> index 70f013e692b0..1d90bde59d21 100644
> --- a/drivers/rtc/rtc-vr41xx.c
> +++ b/drivers/rtc/rtc-vr41xx.c
> @@ -17,6 +17,7 @@
>   *  along with this program; if not, write to the Free Software
>   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
>   */
> +#include <linux/compat.h>
>  #include <linux/err.h>
>  #include <linux/fs.h>
>  #include <linux/init.h>
> @@ -79,6 +80,10 @@ static void __iomem *rtc2_base;
>  #define rtc2_read(offset)		readw(rtc2_base + (offset))
>  #define rtc2_write(offset, value)	writew((value), rtc2_base + (offset))
>  
> +/* 32-bit compat for ioctls that nobody else uses */
> +#define RTC_EPOCH_READ32	_IOR('p', 0x0d, compat_ulong_t)
> +#define RTC_EPOCH_SET32		_IOW('p', 0x0e, compat_ulong_t)
> +
>  static unsigned long epoch = 1970;	/* Jan 1 1970 00:00:00 */
>  
>  static DEFINE_SPINLOCK(rtc_lock);
> @@ -195,6 +200,11 @@ static int vr41xx_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long
>  	switch (cmd) {
>  	case RTC_EPOCH_READ:
>  		return put_user(epoch, (unsigned long __user *)arg);
> +#ifdef CONFIG_COMPAT
> +	case RTC_EPOCH_READ32:
> +		return put_user(epoch, (unsigned int __user *)arg);
> +	case RTC_EPOCH_SET32:

checkpatch complains about the missing fallthrough comment now.

> +#endif
>  	case RTC_EPOCH_SET:
>  		/* Doesn't support before 1900 */
>  		if (arg < 1900)
> diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
> index 5c37104b8805..9237076bdcf5 100644
> --- a/fs/compat_ioctl.c
> +++ b/fs/compat_ioctl.c
> @@ -46,7 +46,6 @@
>  #include <linux/raw.h>
>  #include <linux/blkdev.h>
>  #include <linux/elevator.h>
> -#include <linux/rtc.h>
>  #include <linux/pci.h>
>  #include <linux/serial.h>
>  #include <linux/if_tun.h>
> @@ -426,37 +425,6 @@ static int serial_struct_ioctl(struct file *file,
>          return err;
>  }
>  
> -#define RTC_IRQP_READ32		_IOR('p', 0x0b, compat_ulong_t)
> -#define RTC_IRQP_SET32		_IOW('p', 0x0c, compat_ulong_t)
> -#define RTC_EPOCH_READ32	_IOR('p', 0x0d, compat_ulong_t)
> -#define RTC_EPOCH_SET32		_IOW('p', 0x0e, compat_ulong_t)
> -
> -static int rtc_ioctl(struct file *file,
> -		unsigned cmd, void __user *argp)
> -{
> -	unsigned long __user *valp = compat_alloc_user_space(sizeof(*valp));
> -	int ret;
> -
> -	if (valp == NULL)
> -		return -EFAULT;
> -	switch (cmd) {
> -	case RTC_IRQP_READ32:
> -	case RTC_EPOCH_READ32:
> -		ret = do_ioctl(file, (cmd == RTC_IRQP_READ32) ?
> -					RTC_IRQP_READ : RTC_EPOCH_READ,
> -					(unsigned long)valp);
> -		if (ret)
> -			return ret;
> -		return convert_in_user(valp, (unsigned int __user *)argp);
> -	case RTC_IRQP_SET32:
> -		return do_ioctl(file, RTC_IRQP_SET, (unsigned long)argp);
> -	case RTC_EPOCH_SET32:
> -		return do_ioctl(file, RTC_EPOCH_SET, (unsigned long)argp);
> -	}
> -
> -	return -ENOIOCTLCMD;
> -}
> -
>  /* on ia32 l_start is on a 32-bit boundary */
>  #if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
>  struct space_resv_32 {
> @@ -609,21 +577,6 @@ COMPATIBLE_IOCTL(SCSI_IOCTL_GET_PCI)
>  /* Big V (don't complain on serial console) */
>  IGNORE_IOCTL(VT_OPENQRY)
>  IGNORE_IOCTL(VT_GETMODE)
> -/* Little p (/dev/rtc, /dev/envctrl, etc.) */
> -COMPATIBLE_IOCTL(RTC_AIE_ON)
> -COMPATIBLE_IOCTL(RTC_AIE_OFF)
> -COMPATIBLE_IOCTL(RTC_UIE_ON)
> -COMPATIBLE_IOCTL(RTC_UIE_OFF)
> -COMPATIBLE_IOCTL(RTC_PIE_ON)
> -COMPATIBLE_IOCTL(RTC_PIE_OFF)
> -COMPATIBLE_IOCTL(RTC_WIE_ON)
> -COMPATIBLE_IOCTL(RTC_WIE_OFF)
> -COMPATIBLE_IOCTL(RTC_ALM_SET)
> -COMPATIBLE_IOCTL(RTC_ALM_READ)
> -COMPATIBLE_IOCTL(RTC_RD_TIME)
> -COMPATIBLE_IOCTL(RTC_SET_TIME)
> -COMPATIBLE_IOCTL(RTC_WKALM_SET)
> -COMPATIBLE_IOCTL(RTC_WKALM_RD)
>  /*
>   * These two are only for the sbus rtc driver, but
>   * hwclock tries them on every rtc device first when
> @@ -1005,12 +958,6 @@ static long do_ioctl_trans(unsigned int cmd,
>  	case TIOCGSERIAL:
>  	case TIOCSSERIAL:
>  		return serial_struct_ioctl(file, cmd, argp);
> -	/* Not implemented in the native kernel */
> -	case RTC_IRQP_READ32:
> -	case RTC_IRQP_SET32:
> -	case RTC_EPOCH_READ32:
> -	case RTC_EPOCH_SET32:
> -		return rtc_ioctl(file, cmd, argp);
>  	}
>  
>  	/*
> -- 
> 2.18.0
> 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v2 2/2] rtc: move compat_ioctl handling into rtc-dev.c

[Arnd Bergmann]

On Sat, Sep 8, 2018 at 10:17 AM Alexandre Belloni
<alexandre.belloni@bootlin.com> wrote:
>
> On 28/08/2018 16:26:31+0200, Arnd Bergmann wrote:
> > We no longer need the rtc compat handling to be in common code, now that
> > all drivers are either moved to the rtc-class framework, or (rarely)
> > exist in drivers/char for architectures without compat mode (m68k,
> > alpha and ia64, respectively).
> This doesn't apply on v4.19-rc1, can you rebase?

I must have based it  on top of another compat_ioctl.c change that I sent.

Independently, I also sent a longer series of changes to Al now, which also
need to be rebased. I'd suggest that you just keep the Kconfig change for
MIPS then (or offload that to its arch maintainers), and I'll add the RTC patch
to the series for Al instead.

        Arnd