From: alekskartashov@parallels•com (Alexander Kartashov)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm: align shared memory unconditionally to the SHMLBA boundary
Date: Tue, 16 Jul 2013 17:12:06 +0400 [thread overview]
Message-ID: <51E546A6.7010606@parallels.com> (raw)
In-Reply-To: <20130716110721.GD24642@n2100.arm.linux.org.uk>
On 07/16/2013 03:07 PM, Russell King - ARM Linux wrote:
> On Tue, Jul 16, 2013 at 02:47:45PM +0400, Alexander Kartashov wrote:
>> On 07/16/2013 02:36 PM, Russell King - ARM Linux wrote:
>>> shmget() doesn't allocate space in the process for the SHM region. It
>>> merely creates the shm memory and returns an identifier for it which can
>>> later be used by shmat() to map it.
>> Thank you for the correction, I meant shmat() in that comment indeed.
>> I'm sorry for the inconvenience.
> Right, so it appears that there's a difference between shmat() with an
> address and with a NULL address, because the enforcement is done by two
> completely different bits of code in unrelated parts of the kernel.
>
> I notice Sparc32 seems to have a fix for this along the lines of the
> (untested) patch below, so let's do the same on ARM. Please test this
> and let me know if this solves your problem.
>
> Thanks.
>
> arch/arm/include/asm/shmparam.h | 8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/include/asm/shmparam.h b/arch/arm/include/asm/shmparam.h
> index a5223b3..843db59 100644
> --- a/arch/arm/include/asm/shmparam.h
> +++ b/arch/arm/include/asm/shmparam.h
> @@ -1,16 +1,16 @@
> #ifndef _ASMARM_SHMPARAM_H
> #define _ASMARM_SHMPARAM_H
>
> +#include <asm/cachetype.h>
> +
> /*
> * This should be the size of the virtually indexed cache/ways,
> * or page size, whichever is greater since the cache aliases
> * every size/ways bytes.
> */
> -#define SHMLBA (4 * PAGE_SIZE) /* attach addr a multiple of this */
> +#define SHMLBA (cache_is_vipt_aliasing() ? (4 * PAGE_SIZE) : PAGE_SIZE)
This change breaks compilation:
arch/arm/mm/copypage-v6.c:23:5: warning: "cacheid_is" is not defined
[-Wundef]
arch/arm/mm/copypage-v6.c:23:5: error: missing binary operator before
token "("
make[1]: *** [arch/arm/mm/copypage-v6.o] Error 1
make: *** [arch/arm/mm] Error 2
The lines in trouble is
#if SHMLBA > 16384
#error FIX ME
#endif
>
> -/*
> - * Enforce SHMLBA in shmat
> - */
> +/* Enforce SHMLBA in shmat */
> #define __ARCH_FORCE_SHMLBA
>
> #endif /* _ASMARM_SHMPARAM_H */
--
Sincerely yours,
Alexander Kartashov
Intern
Core team
www.parallels.com
Skype: aleksandr.kartashov
Email: alekskartashov at parallels.com
next prev parent reply other threads:[~2013-07-16 13:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 6:11 [PATCH] arm: align shared memory unconditionally to the SHMLBA boundary Alexander Kartashov
2013-07-15 17:32 ` Cyrill Gorcunov
2013-07-15 18:08 ` Russell King - ARM Linux
2013-07-15 18:57 ` Cyrill Gorcunov
2013-07-16 5:37 ` Alexander Kartashov
2013-07-16 9:53 ` Cyrill Gorcunov
2013-07-16 10:22 ` Alexander Kartashov
2013-07-16 10:36 ` Russell King - ARM Linux
2013-07-16 10:47 ` Alexander Kartashov
2013-07-16 11:07 ` Russell King - ARM Linux
2013-07-16 13:12 ` Alexander Kartashov [this message]
2013-08-16 8:20 ` Alexander Kartashov
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