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From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: y2038@lists.linaro.org, linux-api@vger.kernel.org,
	linux-kernel@vger.kernel.org, ink@jurassic.park.msu.ru,
	mattst88@gmail.com, linux@armlinux.org.uk,
	catalin.marinas@arm.com, will.deacon@arm.com,
	tony.luck@intel.com, fenghua.yu@intel.com, geert@linux-m68k.org,
	monstr@monstr.eu, paul.burton@mips.com, deller@gmx.de,
	mpe@ellerman.id.au, schwidefsky@de.ibm.com, dalias@libc.org,
	davem@davemloft.net, luto@kernel.org, tglx@linutronix.de,
	mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
	jcmvbkbc@gmail.com, firoz.khan@linaro.org, ebiederm@xmission.com,
	deepa.kernel@gmail.com, linux@dominikbrodowski.net,
	akpm@linux-foundation.org, dave@stgolabs.net,
	linux-alpha@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	sparclinux@vger.kernel.org
Subject: Re: [PATCH 14/15] arch: add split IPC system calls where needed
Date: Thu, 10 Jan 2019 21:32:53 +0100	[thread overview]
Message-ID: <20190110203253.GA3676@osiris> (raw)
In-Reply-To: <20190110162435.309262-15-arnd@arndb.de>

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@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.

> 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.


  reply	other threads:[~2019-01-10 20:33 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10 16:24 [PATCH 00/15] arch: synchronize syscall tables in preparation for y2038 Arnd Bergmann
2019-01-10 16:24 ` [PATCH 01/15] ia64: add __NR_umount2 definition Arnd Bergmann
2019-01-10 16:24 ` [PATCH 02/15] ia64: add statx and io_pgetevents syscalls Arnd Bergmann
2019-01-10 16:24 ` [PATCH 03/15] ia64: assign syscall numbers for perf and seccomp Arnd Bergmann
2019-01-10 16:24 ` [PATCH 04/15] alpha: wire up io_pgetevents system call Arnd Bergmann
2019-01-10 16:24 ` [PATCH 05/15] alpha: update syscall macro definitions Arnd Bergmann
2019-01-10 16:24 ` [PATCH 06/15] ARM: add migrate_pages() system call Arnd Bergmann
2019-01-10 16:32   ` Will Deacon
2019-01-10 17:11     ` Arnd Bergmann
2019-01-10 16:24 ` [PATCH 07/15] ARM: add kexec_file_load system call number Arnd Bergmann
2019-01-10 16:39   ` Will Deacon
2019-01-10 17:14     ` Arnd Bergmann
2019-01-10 16:24 ` [PATCH 08/15] m68k: assign syscall number for seccomp Arnd Bergmann
2019-01-10 16:24 ` [PATCH 09/15] sh: remove duplicate unistd_32.h file Arnd Bergmann
2019-01-10 16:24 ` [PATCH 10/15] sh: add statx system call Arnd Bergmann
2019-01-10 16:24 ` [PATCH 11/15] mips: fix n32 compat_ipc_parse_version Arnd Bergmann
2019-01-10 16:24 ` [PATCH 12/15] sparc64: fix sparc_ipc type conversion Arnd Bergmann
2019-01-10 16:24 ` [PATCH 13/15] ipc: rename old-style shmctl/semctl/msgctl syscalls Arnd Bergmann
2019-01-10 16:24 ` [PATCH 14/15] arch: add split IPC system calls where needed Arnd Bergmann
2019-01-10 20:32   ` Heiko Carstens [this message]
2019-01-11 17:33     ` Arnd Bergmann
2019-01-14  3:40   ` Michael Ellerman
2019-01-14  3:59   ` Michael Ellerman
2019-01-14  9:58     ` Michael Ellerman
2019-01-15 15:01     ` Arnd Bergmann
2019-01-15 15:18       ` Arnd Bergmann
2019-01-15 16:35         ` Geert Uytterhoeven
2019-01-15 21:24           ` Arnd Bergmann
2019-01-16  0:09         ` Michael Ellerman
2019-01-16  0:10       ` Michael Ellerman
2019-01-10 16:24 ` [PATCH 15/15] arch: add pkey and rseq syscall numbers everywhere Arnd Bergmann
2019-01-10 20:36   ` Heiko Carstens
2019-01-11 17:30     ` Arnd Bergmann
2019-01-14  8:31       ` Heiko Carstens
2019-01-15 11:52   ` Russell King - ARM Linux admin
2019-01-15 14:47     ` Arnd Bergmann
2019-01-10 16:59 ` [PATCH 00/15] arch: synchronize syscall tables in preparation for y2038 Geert Uytterhoeven
2019-01-10 17:06   ` Arnd Bergmann
2019-01-10 18:11     ` Geert Uytterhoeven
2019-01-10 22:43       ` Arnd Bergmann
2019-01-11  8:07         ` Geert Uytterhoeven
2019-01-10 18:10 ` Joseph Myers
2019-01-10 22:42   ` Arnd Bergmann
2019-01-10 23:14     ` Michael Cree

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