From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
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Subject: Re: [PATCH v2 29/29] y2038: add 64-bit time_t syscalls to all 32-bit architectures
Date: Sat, 19 Jan 2019 14:28:52 +0000 [thread overview]
Message-ID: <20190119142852.cntdihah4mpa3lgx@e5254000004ec.dyn.armlinux.org.uk> (raw)
In-Reply-To: <CALCETrWPj6dHEyo=AELoVjXGsiwuSpRp17x3CEWBHvp7i3cy+Q@mail.gmail.com>
On Fri, Jan 18, 2019 at 11:53:25AM -0800, Andy Lutomirski wrote:
> On Fri, Jan 18, 2019 at 11:33 AM Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > On Fri, Jan 18, 2019 at 7:50 PM Andy Lutomirski <luto@kernel.org> wrote:
> > > On Fri, Jan 18, 2019 at 8:25 AM Arnd Bergmann <arnd@arndb.de> wrote:
> > > > - Once we get to 512, we clash with the x32 numbers (unless
> > > > we remove x32 support first), and probably have to skip
> > > > a few more. I also considered using the 512..547 space
> > > > for 32-bit-only calls (which never clash with x32), but
> > > > that also seems to add a bit of complexity.
> > >
> > > I have a patch that I'll send soon to make x32 use its own table. As
> > > far as I'm concerned, 547 is *it*. 548 is just a normal number and is
> > > not special. But let's please not reuse 512..547 for other purposes
> > > on x86 variants -- that way lies even more confusion, IMO.
> >
> > Fair enough, the space for those numbers is cheap enough here.
> > I take it you mean we also should not reuse that number space if
> > we were to decide to remove x32 soon, but you are not worried
> > about clashing with arch/alpha when everything else uses consistent
> > numbers?
> >
>
> I think we have two issues if we reuse those numbers for new syscalls.
> First, I'd really like to see new syscalls be numbered consistently
> everywhere, or at least on all x86 variants, and we can't on x32
> because they mean something else. Perhaps more importantly, due to
> what is arguably a rather severe bug, issuing a native x86_64 syscall
> (x32 bit clear) with nr in the range 512..547 does *not* return
> -ENOSYS on a kernel with x32 enabled. Instead it does something that
> is somewhat arbitrary. With my patch applied, it will return -ENOSYS,
> but old kernels will still exist, and this will break syscall probing.
>
> Can we perhaps just start the consistent numbers above 547 or maybe
> block out 512..547 in the new regime?
I don't think you gain much with that kind of scheme - it won't take
very long before an architecture misses having a syscall added, and
then someone else adds their own. Been there with ARM - I was keeping
the syscall table in the same order as x86 for new syscalls, but now
that others have been adding syscalls to the table since I converted
ARM to the tabular form, that's now gone out the window.
So, I think it's completely pointless to do what you're suggesting.
We'll just end up with a big hole in the middle of the syscall table
and then revert back to random numbering of syscalls thereafter again.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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According to speedtest.net: 11.9Mbps down 500kbps up
next prev parent reply other threads:[~2019-01-19 14:29 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 16:18 [PATCH v2 00/29] y2038: add time64 syscalls Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 01/29] ia64: add __NR_umount2 definition Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 02/29] ia64: add statx and io_pgetevents syscalls Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 03/29] ia64: assign syscall numbers for perf and seccomp Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 04/29] alpha: wire up io_pgetevents system call Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 05/29] alpha: update syscall macro definitions Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 06/29] ARM: add migrate_pages() system call Arnd Bergmann
2019-01-25 15:16 ` Catalin Marinas
2019-01-18 16:18 ` [PATCH v2 07/29] ARM: add kexec_file_load system call number Arnd Bergmann
2019-01-25 15:43 ` Catalin Marinas
2019-01-25 16:21 ` Russell King - ARM Linux admin
2019-01-18 16:18 ` [PATCH v2 08/29] m68k: assign syscall number for seccomp Arnd Bergmann
2019-01-21 8:55 ` Geert Uytterhoeven
2019-01-18 16:18 ` [PATCH v2 09/29] sh: remove duplicate unistd_32.h file Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 10/29] sh: add statx system call Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 11/29] sparc64: fix sparc_ipc type conversion Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 12/29] ipc: rename old-style shmctl/semctl/msgctl syscalls Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 13/29] arch: add split IPC system calls where needed Arnd Bergmann
2019-01-18 17:18 ` Gabriel Paubert
2019-01-18 19:30 ` Arnd Bergmann
2019-01-21 8:55 ` Geert Uytterhoeven
2019-01-21 11:57 ` Heiko Carstens
2019-01-18 16:18 ` [PATCH v2 14/29] arch: add pkey and rseq syscall numbers everywhere Arnd Bergmann
2019-01-21 8:55 ` Geert Uytterhoeven
2019-01-21 20:28 ` Arnd Bergmann
2019-01-21 11:59 ` Heiko Carstens
2019-01-18 16:18 ` [PATCH v2 15/29] alpha: add standard statfs64/fstatfs64 syscalls Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 16/29] alpha: add generic get{eg,eu,g,p,u,pp}id() syscalls Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 17/29] syscalls: remove obsolete __IGNORE_ macros Arnd Bergmann
2019-01-21 11:59 ` Heiko Carstens
2019-01-18 16:18 ` [PATCH v2 18/29] time: make adjtime compat handling available for 32 bit Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 19/29] time: Add struct __kernel_timex Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 20/29] time: fix sys_timer_settime prototype Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 21/29] sparc64: add custom adjtimex/clock_adjtime functions Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 22/29] timex: use __kernel_timex internally Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 23/29] timex: change syscalls to use struct __kernel_timex Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 24/29] x86/x32: use time64 versions of sigtimedwait and recvmmsg Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 26/29] y2038: use time32 syscall names on 32-bit Arnd Bergmann
2019-01-21 8:07 ` Geert Uytterhoeven
2019-01-21 8:56 ` Geert Uytterhoeven
2019-01-18 16:18 ` [PATCH v2 27/29] y2038: remove struct definition redirects Arnd Bergmann
2019-01-18 16:18 ` [PATCH v2 28/29] y2038: rename old time and utime syscalls Arnd Bergmann
2019-01-21 8:56 ` Geert Uytterhoeven
2019-01-21 12:15 ` Heiko Carstens
2019-01-18 16:18 ` [PATCH v2 29/29] y2038: add 64-bit time_t syscalls to all 32-bit architectures Arnd Bergmann
2019-01-18 18:50 ` Andy Lutomirski
2019-01-18 19:33 ` Arnd Bergmann
2019-01-18 19:53 ` Andy Lutomirski
2019-01-18 20:44 ` Arnd Bergmann
2019-01-19 14:28 ` Russell King - ARM Linux admin [this message]
2019-01-21 8:19 ` Geert Uytterhoeven
2019-01-21 17:08 ` Arnd Bergmann
2019-01-21 20:40 ` Arnd Bergmann
2019-01-21 8:56 ` Geert Uytterhoeven
2019-01-21 12:19 ` Heiko Carstens
2019-01-21 16:31 ` Arnd Bergmann
2019-01-25 15:55 ` Catalin Marinas
2019-01-18 16:57 ` [PATCH v2 00/29] y2038: add time64 syscalls Dennis Clarke
2019-01-18 17:14 ` Arnd Bergmann
2019-01-18 17:19 ` Dennis Clarke
2019-01-18 17:45 ` James Bottomley
[not found] ` <20190118161835.2259170-26-arnd@arndb.de>
2019-01-25 15:47 ` [PATCH v2 25/29] y2038: syscalls: rename y2038 compat syscalls Catalin Marinas
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