From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] x86_64: Implement personality ADDR_LIMIT_32BIT
Date: Fri, 3 Oct 2008 12:25:52 +0300 [thread overview]
Message-ID: <20081003092550.GA8669@localhost.localdomain> (raw)
In-Reply-To: <20081003080244.GC25408@elte.hu>
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On Fri, Oct 03, 2008 at 10:02:44AM +0200, Ingo Molnar wrote:
>
> * Kirill A. Shutemov <kirill@shutemov.name> wrote:
>
> > - /* for MAP_32BIT mappings we force the legact mmap base */
> > - if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT))
> > + /* for MAP_32BIT mappings and ADDR_LIMIT_32BIT personality we force the
> > + * legact mmap base
> > + */
>
> please use the customary multi-line comment style:
>
> /*
> * Comment .....
> * ...... goes here:
> */
>
> and you might use the opportunity to fix the s/legact/legacy typo as
> well.
Ok, I'll fix it.
>
> but more generally, we already have ADDR_LIMIT_3GB support on x86.
Does ADDR_LIMIT_3GB really work?
$ cat 1.c
#include <stdio.h>
#include <sys/personality.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define ADDR_LIMIT_3GB 0x8000000
int main(void)
{
int id;
void *shm;
personality(ADDR_LIMIT_3GB);
id = shmget(0x123456, 1, IPC_CREAT | 0600);
shm = shmat(id, NULL, 0);
printf("shm: %p\n", shm);
shmdt(shm);
return 0;
}
$ gcc -Wall 1.c
$ sudo ./a.out
shm: 0x7f4fca755000
> Why
> should support for ADDR_LIMIT_32BIT be added?
It's useful for user mode qemu when you try emulate 32-bit target on
x86_64. For example, if shmat(2) return addres above 32-bit, target will
get SIGSEGV on access to it.
--
Regards, Kirill A. Shutemov
+ Belarus, Minsk
+ ALT Linux Team, http://www.altlinux.com/
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next prev parent reply other threads:[~2008-10-03 9:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-03 7:04 [PATCH] x86_64: Implement personality ADDR_LIMIT_32BIT Kirill A. Shutemov
2008-10-03 8:02 ` Ingo Molnar
2008-10-03 9:25 ` Kirill A. Shutemov [this message]
2008-10-03 12:44 ` Arjan van de Ven
2008-10-03 12:58 ` Kirill A. Shutemov
2008-10-06 6:13 ` Andi Kleen
2008-10-06 8:17 ` Kirill A. Shutemov
2008-10-06 8:42 ` Andi Kleen
2008-10-06 9:17 ` Kirill A. Shutemov
2008-10-06 9:56 ` Andi Kleen
2008-10-06 10:12 ` Kirill A. Shutemov
2008-10-06 13:26 ` Andi Kleen
2008-10-06 14:37 ` [PATCH, RFC] shmat: introduce flag SHM_MAP_HINT Kirill A. Shutemov
2008-10-06 19:29 ` Andi Kleen
2008-10-07 6:57 ` Kirill A. Shutemov
2008-10-07 6:57 ` [PATCH, RFC, v2] " Kirill A. Shutemov
2008-10-07 8:20 ` Andi Kleen
2008-10-07 10:09 ` Kirill A. Shutemov
2008-10-07 11:26 ` Andi Kleen
2008-10-07 11:23 ` Kirill A. Shutemov
2008-10-07 14:38 ` Hugh Dickins
2008-10-07 15:10 ` Andi Kleen
2008-10-07 11:08 ` [PATCH, RFC] " KOSAKI Motohiro
2008-10-07 11:21 ` Andi Kleen
2008-10-07 11:21 ` Kirill A. Shutemov
2008-10-07 11:26 ` KOSAKI Motohiro
2008-10-07 11:30 ` Kirill A. Shutemov
2008-10-07 11:50 ` Andi Kleen
2008-10-07 11:24 ` Kirill A. Shutemov
2008-10-07 12:31 ` Alan Cox
2008-10-07 13:14 ` Andi Kleen
2008-10-03 9:33 ` [PATCH] x86_64: Implement personality ADDR_LIMIT_32BIT Kirill A. Shutemov
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