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From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: "Alexander Graf" <agraf@suse.de>,
	"Will Deacon" <will.deacon@arm.com>,
	"Catalin Marinas" <Catalin.Marinas@arm.com>,
	"Michael Matz" <matz@suse.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Dirk Müller" <dmueller@suse.com>,
	"Suravee Suthikulanit" <suravee.suthikulpanit@amd.com>,
	"Andreas Schwab" <schwab@suse.de>
Subject: Re: [PATCH] arm64: Enable CONFIG_COMPAT also for 64k page size
Date: Wed, 11 Mar 2015 13:47:36 +0100	[thread overview]
Message-ID: <5396604.TRferrWZgF@wuerfel> (raw)
In-Reply-To: <550025E0.7030008@suse.de>

On Wednesday 11 March 2015 06:24:16 Alexander Graf wrote:
> So after recompiling all of the distribution with newer binutils we now
> have an openSUSE Factory tree that has 64k aligned 32bit binaries.
> 
> Unfortunately however, the 32bit glibc has a bogus mmap() implementation
> that hard codes 4k page size.
> 
> With the patch below applied to glibc, I can successfully run 32bit user
> space on Seattle with 64k PAGE_SIZE though. So I guess we'll need to fix
> up glibc next.
> 
> Do you know of anyone who's fluent enough in 32bit ARM assembly to
> convert the hard coded assumptions in there to instead use a variable
> that takes the actual host page size into account?

I believe this is a kernel bug, and the kernel API for 32-bit emulation
should always take the pgoff argument in 4KB units instead of PAGE_SIZE
units, see the implementation of sys_mmap2 in
arch/powerpc/kernel/sys_ppc32.c.

All user space programs that call mmap2 still need to make sure that
their arguments are PAGE_SIZE aligned, but the libc need not care
about this here.

	Arnd

  parent reply	other threads:[~2015-03-11 12:47 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-04 15:46 [PATCH] arm64: Enable CONFIG_COMPAT also for 64k page size Alexander Graf
2014-12-04 18:18 ` Laura Abbott
2014-12-04 18:20 ` Will Deacon
2014-12-04 23:37   ` Alexander Graf
2014-12-08 13:47     ` Michael Matz
2014-12-06 17:23   ` Alexander Graf
2014-12-08 10:10     ` Will Deacon
2014-12-08 10:47       ` Alexander Graf
2015-03-11 11:24       ` Alexander Graf
2015-03-11 12:43         ` Andreas Schwab
2015-03-11 12:47         ` Arnd Bergmann [this message]
2015-03-11 13:08           ` Alexander Graf
2015-03-11 13:35             ` Andreas Schwab
2015-03-11 13:51               ` Arnd Bergmann
2015-03-11 13:57                 ` Andreas Schwab
2015-03-11 15:44                   ` Alexander Graf
2015-03-11 16:09                     ` Andreas Schwab
2015-03-11 18:11                       ` Alexander Graf
2015-03-12  9:07                         ` [PATCH] arm64: fix implementation of mmap2 compat syscall Andreas Schwab
2015-03-16 14:16           ` [PATCH] arm64: Enable CONFIG_COMPAT also for 64k page size Christopher Covington
2015-03-16 14:19             ` Arnd Bergmann
2014-12-04 21:15 ` Olof Johansson
2014-12-04 23:41   ` Alexander Graf
2014-12-04 23:48     ` Olof Johansson
2014-12-05 10:39       ` Arnd Bergmann
2014-12-05 11:05         ` Catalin Marinas
2014-12-05 12:24           ` Arnd Bergmann
2014-12-05 12:31             ` Catalin Marinas
2015-02-18 13:40           ` Christopher Covington
2014-12-05 12:06         ` Alexander Graf
2014-12-05 11:14   ` Catalin Marinas
2014-12-05 11:35     ` Will Deacon
2015-03-13  4:44     ` Jon Masters
2014-12-05 16:35 ` Liviu Dudau

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