Merge tag 'y2038-timekeeping' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground into timers/core

Pull y2038 timekeeping syscall changes from Arnd Bergmann:

This is the first set of system call entry point changes to enable 32-bit
architectures to have variants on both 32-bit and 64-bit time_t. Typically
these system calls take a 'struct timespec' argument, but that structure
is defined in user space by the C library and its layout will change.

The kernel already supports handling the 32-bit time_t on 64-bit
architectures through the CONFIG_COMPAT mechanism. As there are a total
of 51 system calls suffering from this problem, reusing that mechanism
on 32-bit architectures.

We already have patches for most of the remaining system calls, but this
set contains most of the complexity and is best tested.  There was one
last-minute regression that prevented it from going into 4.17, but that
is fixed now.

More details from Deepa's patch series description:

   Big picture is as per the lwn article:
   https://lwn.net/Articles/643234/ [2]

   The series is directed at converting posix clock syscalls:
   clock_gettime, clock_settime, clock_getres and clock_nanosleep
   to use a new data structure __kernel_timespec at syscall boundaries.
   __kernel_timespec maintains 64 bit time_t across all execution modes.

   vdso will be handled as part of each architecture when they enable
   support for 64 bit time_t.

   The compat syscalls are repurposed to provide backward compatibility
   by using them as native syscalls as well for 32 bit architectures.
   They will continue to use timespec at syscall boundaries.

   CONFIG_64_BIT_TIME controls whether the syscalls use __kernel_timespec
   or timespec at syscall boundaries.

   The series does the following:
   1. Enable compat syscalls on 32 bit architectures.
   2. Add a new __kernel_timespec type to be used as the data structure
      for all the new syscalls.
   3. Add new config CONFIG_64BIT_TIME(intead of the CONFIG_COMPAT_TIME in
      [1] and [2] to switch to new definition of __kernel_timespec. It is
      the same as struct timespec otherwise.
   4. Add new CONFIG_32BIT_TIME to conditionally compile compat syscalls.

1 files changed, 17 insertions, 7 deletions

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index b6899b5060bd..c21f4c4f8660 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1041,7 +1041,7 @@ void exit_itimers(struct signal_struct *sig)
 }
 
 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
-		const struct timespec __user *, tp)
+		const struct __kernel_timespec __user *, tp)
 {
 	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 new_tp;
@@ -1056,7 +1056,7 @@ SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 }
 
 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
-		struct timespec __user *,tp)
+		struct __kernel_timespec __user *, tp)
 {
 	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 kernel_tp;
@@ -1097,7 +1097,7 @@ SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 }
 
 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
-		struct timespec __user *, tp)
+		struct __kernel_timespec __user *, tp)
 {
 	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 rtn_tp;
@@ -1114,7 +1114,7 @@ SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 	return error;
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
 
 COMPAT_SYSCALL_DEFINE2(clock_settime, clockid_t, which_clock,
 		       struct compat_timespec __user *, tp)
@@ -1149,6 +1149,10 @@ COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
 	return err;
 }
 
+#endif
+
+#ifdef CONFIG_COMPAT
+
 COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
 		       struct compat_timex __user *, utp)
 {
@@ -1173,6 +1177,10 @@ COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
 	return err;
 }
 
+#endif
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
 COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
 		       struct compat_timespec __user *, tp)
 {
@@ -1204,8 +1212,8 @@ static int common_nsleep(const clockid_t which_clock, int flags,
 }
 
 SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
-		const struct timespec __user *, rqtp,
-		struct timespec __user *, rmtp)
+		const struct __kernel_timespec __user *, rqtp,
+		struct __kernel_timespec __user *, rmtp)
 {
 	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 t;
@@ -1228,7 +1236,8 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 	return kc->nsleep(which_clock, flags, &t);
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
 COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
 		       struct compat_timespec __user *, rqtp,
 		       struct compat_timespec __user *, rmtp)
@@ -1253,6 +1262,7 @@ COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
 
 	return kc->nsleep(which_clock, flags, &t);
 }
+
 #endif
 
 static const struct k_clock clock_realtime = {