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SubjectRe: [PATCH v2 06/17] compat_ioctl: move rtc handling into rtc-dev.c
On 12/09/2018 17:08:53+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>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
> 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 | 54 ----------------------------------------
> 3 files changed, 22 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
> index 43d962a9c210..ccd5b1795e20 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 = generic_compat_ioctl_ptrarg,
> .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 2d7c7e149083..312b52b4e974 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>
> @@ -633,37 +632,6 @@ 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 {
> @@ -816,21 +784,6 @@ 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
> @@ -1307,13 +1260,6 @@ 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);
> -
> /* dvb */
> case VIDEO_GET_EVENT:
> return do_video_get_event(file, cmd, argp);
> --
> 2.18.0
>

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

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