linux-kernel - [RFC PATCH v2 2/4] time64: add timeval64 helper for compat syscalls

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Date:	Mon, 29 Jun 2015 22:23:25 +0800
From:	Bamvor Zhang Jian <bamvor.zhangjian@...aro.org>
To:	arnd@...db.de, john.stultz@...aro.org, tglx@...utronix.de
Cc:	y2039@...ts.linaro.org, linux-kernel@...r.kernel.org,
	bamvor.zhangjian@...aro.org
Subject: [RFC PATCH v2 2/4] time64: add timeval64 helper for compat syscalls

Add __kernel_compat_timeval in uapi in order to use it in ioctl
command because compat_timeval is invisible in uapi. Meanwhile
We could avoid to define it by using the __s32 array in ioctl
command definition. I am sure which one is the better way.
Any suggestion or input is welcome.

This patch also define compat_get_timeval64, compat_put_timeval64
 for converting between compat_timeval and timeval64.

Signed-off-by: Bamvor Zhang Jian <bamvor.zhangjian@...aro.org>
---
 include/linux/compat.h    |  3 +++
 include/uapi/linux/time.h |  6 ++++++
 kernel/compat.c           | 17 +++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index ab25814..14569a7 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -154,6 +154,9 @@ extern int compat_get_timespec(struct timespec *, const void __user *);
 extern int compat_put_timespec(const struct timespec *, void __user *);
 extern int compat_get_timeval(struct timeval *, const void __user *);
 extern int compat_put_timeval(const struct timeval *, void __user *);
+struct timeval64;
+extern int compat_get_timeval64(struct timeval64 *tv, const struct compat_timeval __user *ctv);
+extern int compat_put_timeval64(const struct timeval64 *tv, struct compat_timeval __user *ctv);
 
 /*
  * This function convert a timespec if necessary and returns a *user
diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h
index 2ca6a31..9f6093e 100644
--- a/include/uapi/linux/time.h
+++ b/include/uapi/linux/time.h
@@ -76,4 +76,10 @@ struct __kernel_timeval {
 };
 #endif
 
+typedef __s32 __kernel_time32_t;
+struct __kernel_compat_timeval {
+       __kernel_time32_t       tv_sec;
+       __s32                   tv_usec;
+};
+
 #endif /* _UAPI_LINUX_TIME_H */
diff --git a/kernel/compat.c b/kernel/compat.c
index 333d364..ebe45b4 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -172,6 +172,23 @@ int compat_put_timeval(const struct timeval *tv, void __user *utv)
 }
 EXPORT_SYMBOL_GPL(compat_put_timeval);
 
+int compat_get_timeval64(struct timeval64 *tv, const struct compat_timeval __user *ctv)
+{
+	return (!access_ok(VERIFY_READ, ctv, sizeof(*ctv)) ||
+			__get_user(tv->tv_sec, &ctv->tv_sec) ||
+			__get_user(tv->tv_usec, &ctv->tv_usec)) ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(compat_get_timeval64);
+
+/* TODO: is it ok that just put to user without implicit cast? */
+int compat_put_timeval64(const struct timeval64 *tv, struct compat_timeval *ctv)
+{
+	return (!access_ok(VERIFY_WRITE, ctv, sizeof(*ctv)) ||
+			__put_user(tv->tv_sec, &ctv->tv_sec) ||
+			__put_user(tv->tv_usec, &ctv->tv_usec)) ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(compat_put_timeval64);
+
 int compat_get_timespec(struct timespec *ts, const void __user *uts)
 {
 	if (COMPAT_USE_64BIT_TIME)
-- 
2.1.4

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