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From:   Arnd Bergmann <arnd@arndb.de>
To:     linux-rtc@vger.kernel.org
Cc:     a.zummo@towertech.it, alexandre.belloni@bootlin.com,
        keguang.zhang@gmail.com, y2038@lists.linaro.org,
        Arnd Bergmann <arnd@arndb.de>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Kees Cook <keescook@chromium.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH v2 2/2] rtc: move compat_ioctl handling into rtc-dev.c
Date:   Tue, 28 Aug 2018 16:26:31 +0200
Message-Id: <20180828142724.4067857-2-arnd@arndb.de>
In-Reply-To: <20180828142724.4067857-1-arnd@arndb.de>
References: <20180828142724.4067857-1-arnd@arndb.de>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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