Re: [PATCH 14/15] arch: add split IPC system calls where needed
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2019-01-14 03:59:51
Also in:
linux-alpha, linux-api, linux-arm-kernel, linux-mips, linux-sh, lkml, sparclinux
Hi Arnd, Arnd Bergmann [off-list ref] writes:
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@arndb.de> --- 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. --- arch/m68k/kernel/syscalls/syscall.tbl | 11 +++++++++++ arch/mips/kernel/syscalls/syscall_o32.tbl | 11 +++++++++++ arch/powerpc/kernel/syscalls/syscall.tbl | 12 ++++++++++++
I have some changes I'd like to make to our syscall table that will clash with this. I'll try and send them today.
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl index db3bbb8744af..1bffab54ff35 100644 --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl@@ -425,3 +425,15 @@ 386 nospu pkey_mprotect sys_pkey_mprotect 387 nospu rseq sys_rseq 388 nospu io_pgetevents sys_io_pgetevents compat_sys_io_pgetevents +# room for arch specific syscalls +392 64 semtimedop sys_semtimedop +393 common semget sys_semget +394 common semctl sys_semctl compat_sys_semctl +395 common shmget sys_shmget +396 common shmctl sys_shmctl compat_sys_shmctl +397 common shmat sys_shmat compat_sys_shmat +398 common shmdt sys_shmdt +399 common msgget sys_msgget +400 common msgsnd sys_msgsnd compat_sys_msgsnd +401 common msgrcv sys_msgrcv compat_sys_msgrcv +402 common msgctl sys_msgctl compat_sys_msgctl
We already have a gap at 366-377 from when we tried to add the split IPC calls a few years back. I guess I don't mind leaving that gap and using the common numbers as you've done here. But it would be good to add a comment pointing out that we have room at 366 for more arch specific syscalls as well. cheers