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.
