On Thu, Jan 10, 2019 at 05:24:34PM +0100, Arnd Bergmann wrote:
The IPC system call handling is highly inconsistent across architectures, some use sys_ipc, some use separate calls, and some use both. We also have some architectures that require passing IPC_64 in the flags, and others that set it implicitly. For the additon of a y2083 safe semtimedop() system call, I chose to only support the separate entry points, but that requires first supporting the regular ones with their own syscall numbers. The IPC_64 is now implied by the new semctl/shmctl/msgctl system calls even on the architectures that require passing it with the ipc() multiplexer. I'm not adding the new semtimedop() or semop() on 32-bit architectures, those will get implemented using the new semtimedop_time64() version that gets added along with the other time64 calls. Three 64-bit architectures (powerpc, s390 and sparc) get semtimedop(). Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- One aspect here that might be a bit controversial is the use of the same system call numbers across all architectures, synchronizing all of them with the x86-32 numbers. With the new syscall.tbl files, I hope we can just keep doing that in the future, and no longer require the architecture maintainers to assign a number. This is mainly useful for implementers of the C libraries: if we can add future system calls everywhere at the same time, using a particular version of the kernel headers also guarantees that the system call number macro is visible.
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl index 022fc099b628..428cf512a757 100644 --- a/arch/s390/kernel/syscalls/syscall.tbl +++ b/arch/s390/kernel/syscalls/syscall.tbl @@ -391,3 +391,15 @@ 381 common kexec_file_load sys_kexec_file_load compat_sys_kexec_file_load 382 common io_pgetevents sys_io_pgetevents compat_sys_io_pgetevents 383 common rseq sys_rseq compat_sys_rseq +# room for arch specific syscalls +392 64 semtimedop sys_semtimedop - +393 common semget sys_semget sys_semget
...
+395 common shmget sys_shmget sys_shmget
...
+398 common shmdt sys_shmdt sys_shmdt +399 common msgget sys_msgget sys_msgget
These four need compat system call wrappers, unfortunately... (well, actually only shmget and shmdt require them, but let's add them for all four). See arch/s390/kernel/compat_wrapper.c I'm afraid this compat special handling will be even more annoying in the future, since s390 will be the only architecture which requires this special handling. _Maybe_ it would make sense to automatically generate a weak compat system call wrapper for s390 with the SYSCALL_DEFINE macros, but that probably won't work in all cases.
