ipc: introduce ksys_ipc()/compat_ksys_ipc() for s390

The sys_ipc() and compat_ksys_ipc() functions are meant to only
be used from the system call table, not called by another function.

Introduce ksys_*() interfaces for this purpose, as we have done
for many other system calls.

Link: https://lore.kernel.org/lkml/20190116131527.2071570-3-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
[heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/compat_linux.c

@@ -296,7 +296,7 @@ COMPAT_SYSCALL_DEFINE5(s390_ipc, uint, call, int, first, compat_ulong_t, second,
 {
 	if (call >> 16)		/* hack for backward compatibility */
 		return -EINVAL;
-	return compat_sys_ipc(call, first, second, third, ptr, third);
+	return compat_ksys_ipc(call, first, second, third, ptr, third);
 }
 #endif
 

arch/s390/kernel/sys_s390.c

@@ -58,6 +58,7 @@ SYSCALL_DEFINE1(mmap2, struct s390_mmap_arg_struct __user *, arg)
 	return error;
 }
 
+#ifdef CONFIG_SYSVIPC
 /*
  * sys_ipc() is the de-multiplexer for the SysV IPC calls.
  */
@@ -74,8 +75,9 @@ SYSCALL_DEFINE5(s390_ipc, uint, call, int, first, unsigned long, second,
 	 * Therefore we can call the generic variant by simply passing the
 	 * third parameter also as fifth parameter.
 	 */
-	return sys_ipc(call, first, second, third, ptr, third);
+	return ksys_ipc(call, first, second, third, ptr, third);
 }
+#endif /* CONFIG_SYSVIPC */
 
 SYSCALL_DEFINE1(s390_personality, unsigned int, personality)
 {

include/linux/syscalls.h

@@ -1185,6 +1185,10 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
 			      unsigned long prot, unsigned long flags,
 			      unsigned long fd, unsigned long pgoff);
 ssize_t ksys_readahead(int fd, loff_t offset, size_t count);
+int ksys_ipc(unsigned int call, int first, unsigned long second,
+	unsigned long third, void __user * ptr, long fifth);
+int compat_ksys_ipc(u32 call, int first, int second,
+	u32 third, u32 ptr, u32 fifth);
 
 /*
  * The following kernel syscall equivalents are just wrappers to fs-internal

ipc/syscall.c

@@ -17,8 +17,8 @@
 #include <linux/shm.h>
 #include <linux/uaccess.h>
 
-SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
-		unsigned long, third, void __user *, ptr, long, fifth)
+int ksys_ipc(unsigned int call, int first, unsigned long second,
+	unsigned long third, void __user * ptr, long fifth)
 {
 	int version, ret;
 
@@ -106,6 +106,12 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
 		return -ENOSYS;
 	}
 }
+
+SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
+		unsigned long, third, void __user *, ptr, long, fifth)
+{
+	return ksys_ipc(call, first, second, third, ptr, fifth);
+}
 #endif
 
 #ifdef CONFIG_COMPAT
@@ -121,8 +127,8 @@ struct compat_ipc_kludge {
 };
 
 #ifdef CONFIG_ARCH_WANT_OLD_COMPAT_IPC
-COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
-	u32, third, compat_uptr_t, ptr, u32, fifth)
+int compat_ksys_ipc(u32 call, int first, int second,
+	u32 third, compat_uptr_t ptr, u32 fifth)
 {
 	int version;
 	u32 pad;
@@ -195,5 +201,11 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
 
 	return -ENOSYS;
 }
+
+COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
+	u32, third, compat_uptr_t, ptr, u32, fifth)
+{
+	return compat_ksys_ipc(call, first, second, third, ptr, fifth);
+}
 #endif
 #endif

kernel/sys_ni.c

@@ -366,6 +366,7 @@ COND_SYSCALL(kexec_file_load);
 /* s390 */
 COND_SYSCALL(s390_pci_mmio_read);
 COND_SYSCALL(s390_pci_mmio_write);
+COND_SYSCALL(s390_ipc);
 COND_SYSCALL_COMPAT(s390_ipc);
 
 /* powerpc */