From: Jonas Bonn <jonas@southpole.se>
To: Stafford Horne <shorne@gmail.com>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/7] Apply transparent_union attribute to union semun
Date: Mon, 19 Sep 2016 16:26:27 +0200 [thread overview]
Message-ID: <57DFF593.9030200@southpole.se> (raw)
In-Reply-To: <1474036985-20981-2-git-send-email-shorne@gmail.com>
NAK... this breaks other architectures.
The OpenRISC toolchain is broken with regard to this issue. Five years
ago (last I looked) nobody seemed interesting in fixing it. Has anything
changed here?
/Jonas
On 09/16/2016 04:42 PM, Stafford Horne wrote:
> ..From: Jonas Bonn <jonas@southpole.se>
>
> The syscall handler for semctl is written under the assumption that the
> toolchain will pass "small" unions as function parameters directly instead
> of by reference. The union semun is "small" and thus fits this description.
>
> Since it is assumed that the union will be passed directly and not by
> reference, it is safe to access the union members without going via
> get_user.
>
> The OpenRISC architecture, however, passes all unions by reference, thus
> breaking the above assumption.
>
> The technically correct fix here is to mark the union as being transparent
> so that the ABI of the union's first element determines the parameter
> passing method and thus make explicit what's already implied in the function
> definition.
>
> Signed-off-by: Jonas Bonn <jonas@southpole.se>
> Signed-off-by: Stafford Horne <shorne@gmail.com>
> ---
> include/uapi/linux/sem.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/sem.h b/include/uapi/linux/sem.h
> index dd73b90..aabe50f 100644
> --- a/include/uapi/linux/sem.h
> +++ b/include/uapi/linux/sem.h
> @@ -48,7 +48,7 @@ union semun {
> unsigned short __user *array; /* array for GETALL & SETALL */
> struct seminfo __user *__buf; /* buffer for IPC_INFO */
> void __user *__pad;
> -};
> +} __attribute__ ((transparent_union));
>
> struct seminfo {
> int semmap;
next prev parent reply other threads:[~2016-09-19 14:46 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-16 14:42 [PATCH 0/7] openrisc: Misc fixes from backlog Stafford Horne
2016-09-16 14:42 ` [PATCH 1/7] Apply transparent_union attribute to union semun Stafford Horne
2016-09-16 15:57 ` kbuild test robot
2016-09-16 23:37 ` kbuild test robot
2016-09-17 0:06 ` Stafford Horne
2016-09-19 14:26 ` Jonas Bonn [this message]
2016-09-19 14:47 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 2/7] openrisc: fix PTRS_PER_PGD define Stafford Horne
2016-09-19 14:27 ` Jonas Bonn
2016-09-16 14:43 ` [PATCH 3/7] openrisc: restore call-saved regs on sigreturn Stafford Horne
2016-09-19 14:28 ` Jonas Bonn
2016-09-19 14:50 ` Stafford Horne
2016-09-27 13:54 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 4/7] openrisc: Add thread-local storage (TLS) support Stafford Horne
2016-09-19 14:25 ` Jonas Bonn
2016-09-19 14:43 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 5/7] openrisc: Support both old (or32) and new (or1k) toolchain Stafford Horne
2016-09-18 15:26 ` Guenter Roeck
2016-09-19 6:02 ` Stafford Horne
2016-09-19 7:18 ` Guenter Roeck
2016-09-19 9:11 ` Stafford Horne
2016-09-19 13:17 ` Guenter Roeck
2016-09-19 14:04 ` Stafford Horne
2016-09-19 14:35 ` Jonas Bonn
2016-09-19 14:55 ` Guenter Roeck
2016-09-19 15:16 ` Stafford Horne
2016-09-19 14:39 ` Guenter Roeck
2016-09-20 10:01 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 6/7] openrisc: add SMP and NR_CPUS Kconfig options Stafford Horne
2016-09-19 14:31 ` Jonas Bonn
2016-09-19 14:54 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 7/7] openrisc: remove the redundant of_platform_populate Stafford Horne
2016-09-19 14:32 ` Jonas Bonn
2016-09-19 14:58 ` Stafford Horne
2016-09-19 16:14 ` Rob Herring
2016-09-16 14:51 ` [PATCH 0/7] openrisc: Misc fixes from backlog Stafford Horne
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