From: Arnd Bergmann <arnd@arndb.de>
To: Andreas Schwab <schwab@suse.de>
Cc: linux-arm-kernel@lists.infradead.org,
        Yury Norov <ynorov@caviumnetworks.com>, catalin.marinas@arm.com,
        linux-kernel@vger.kernel.org, pinskia@gmail.com,
        Prasun.Kapoor@caviumnetworks.com, Nathan_Lynch@mentor.com,
        agraf@suse.de, klimov.linux@gmail.com, broonie@kernel.org,
        jan.dakinevich@gmail.com, ddaney.cavm@gmail.com,
        bamvor.zhangjian@huawei.com, philipp.tomsich@theobroma-systems.com,
        andrey.konovalov@linaro.org, joseph@codesourcery.com,
        christoph.muellner@theobroma-systems.com
Subject: Re: [PATCH v6 15/19] arm64: ilp32: force IPC_64 in msgctl, shmctl, semctl
Date: Wed, 18 Nov 2015 10:23:55 +0100
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On Wednesday 18 November 2015 09:25:40 Andreas Schwab wrote:
> Arnd Bergmann <arnd@arndb.de> writes:
> 
> > On Wednesday 18 November 2015 00:16:55 Yury Norov wrote:
> >> 
> >> +/* IPC_64 */
> >> +asmlinkage long ilp32_sys_msgctl(int first, int second, void __user *uptr)
> >> +{
> >> +       return compat_sys_msgctl(first, second | IPC_64, uptr);
> >> +}
> >> +#define compat_sys_msgctl              ilp32_sys_msgctl
> >> +
> >> +asmlinkage long ilp32_sys_shmctl(int first, int second, void __user *uptr)
> >> +{
> >> +       return compat_sys_shmctl(first, second | IPC_64, uptr);
> >> +}
> >> +#define compat_sys_shmctl              ilp32_sys_shmctl
> >> +
> >> +asmlinkage long ilp32_sys_semctl(int first, int second, int third, int arg)
> >> +{
> >> +       return compat_sys_semctl(first, second, third | IPC_64, arg);
> >> +}
> >> +#define compat_sys_semctl      ilp32_sys_semctl
> >> 
> >
> > I wonder if this would be any simpler by changing compat_ipc_parse_version()
> 
> This cries for a generic solution.  Other archs migrating to separate
> ipc syscalls will want to avoid the whole IPC_64 business for them, even
> if they need to retain [compat_]ipc_parse_version for sys_ipc
> compatibility.

Agreed. I think all architectures are moving that way now, so we should
really try to get all cases right now.

I've done a complete list of what the architectures (see
https://docs.google.com/spreadsheets/d/18GxXEHE2ywnSr-SPoGFd1ABz6wEM1ex-JMu5lEraaH8/ )

We have these categories:

1. uses IPC_PARSE_VERSION with sys_ipc, and has just introduced
   separate syscalls:

    arm, avr32, powerpc, x86-32

2. uses IPC_PARSE_VERSION with sys_ipc, and has not yet introduced
   separate syscalls (currently producing a compile warning):

   cris, frv, m32r, m68k, mips (o32), mn10300, s390, sh32, sparc

3. uses IPC_PARSE_VERSION with separate syscalls:

   alpha, blackfin, microblaze, mips (n32/64), xtensa

4a. only new-style IPC with separate syscalls:

    ia64, parisc, sh64

4b. only new-style IPC with separate syscalls, using generic syscall
    table:

    arc, arm64, c6x, h8300, hexagon, metag, nios2, openrisc, score,
    tile, unicore32

So we should probably fix 1. and 2. before it's too late, but make
sure we don't break 3. in the process.

	Arnd
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