ipc: add semtimedop syscall/compat_syscall wrappers

Provide ksys_semtimedop() and compat_ksys_semtimedop() wrappers to avoid
in-kernel calls to these syscalls. The ksys_ prefix denotes that these
functions are meant as a drop-in replacement for the syscalls. In
particular, they use the same calling convention as sys_semtimedop() and
compat_sys_semtimedop().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

1 files changed, 18 insertions, 5 deletions

diff --git a/ipc/sem.c b/ipc/sem.c
index a4af04979fd2..e21ceb8b4af1 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -2120,8 +2120,8 @@ out_free:
         return error;
 }
 
-SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
-                unsigned, nsops, const struct timespec __user *, timeout)
+long ksys_semtimedop(int semid, struct sembuf __user *tsops,
+                     unsigned int nsops, const struct timespec __user *timeout)
 {
         if (timeout) {
                 struct timespec64 ts;
@@ -2132,10 +2132,16 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
         return do_semtimedop(semid, tsops, nsops, NULL);
 }
 
+SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
+                unsigned int, nsops, const struct timespec __user *, timeout)
+{
+        return ksys_semtimedop(semid, tsops, nsops, timeout);
+}
+
 #ifdef CONFIG_COMPAT
-COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
-                       unsigned, nsops,
-                       const struct compat_timespec __user *, timeout)
+long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
+                            unsigned int nsops,
+                            const struct compat_timespec __user *timeout)
 {
         if (timeout) {
                 struct timespec64 ts;
@@ -2145,6 +2151,13 @@ COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
         }
         return do_semtimedop(semid, tsems, nsops, NULL);
 }
+
+COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
+                       unsigned int, nsops,
+                       const struct compat_timespec __user *, timeout)
+{
+        return compat_ksys_semtimedop(semid, tsems, nsops, timeout);
+}
 #endif
 
 SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,