From: Stefano Bonifazi <stefboombastic@gmail.com>
To: Mike Frysinger <vapier.adi@gmail.com>
Cc: Mulyadi Santosa <mulyadi.santosa@gmail.com>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] qemu-user: relocating target code weakness
Date: Mon, 24 Jan 2011 21:58:32 +0100 [thread overview]
Message-ID: <4D3DE7F8.6080807@gmail.com> (raw)
In-Reply-To: <AANLkTikbw-dXoRi7ETNnTRxSm+TYD4odQRjaHLrq=cX0@mail.gmail.com>
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Hi!
Thank you for your answer!
> he is telling you what ELF_START_MMAP is all about. it is the base
> address that the linux kernel for that architecture will start giving
> out addresses. so when running Linux on an x86 system, the first
> mmap() a process does will start at 0x80000000 and move up.
>
> although looking at the elfload code quickly, it doesnt seem that this
> is really used anymore. so it probably can be ignored.
Uhmm that makes sense and explains many things like why they can simply
consider always possible that the target is allocated at
elf_ppnt->p_vaddr, without risking it to clash with qemu-user code..
>> Inside load_elf_binary the call to mmap has elf_ppnt->p_vaddr as required
>> starting address (plus alignment) and MAP_FIXED flag.
> review the mmap() man page ... MAP_FIXED is always a *suggestion* and
> never a requirement. the app must check the return value to see what
> the kernel actually gave it.
Sorry, wrong!
*MAP_FIXED*
Don't interpret/addr/ as a hint: place the mapping at exactly that
address. [] If the specified address cannot be used,*mmap*() will fail.[]
http://www.kernel.org/doc/man-pages/online/pages/man2/mmap.2.html
Thank you!
Best regards!
Stefano B.
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next prev parent reply other threads:[~2011-01-24 20:58 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-24 11:34 [Qemu-devel] qemu-user: relocating target code weakness Stefano Bonifazi
2011-01-24 16:29 ` Mulyadi Santosa
2011-01-24 18:16 ` Stefano Bonifazi
2011-01-24 20:00 ` Mike Frysinger
2011-01-24 20:58 ` Stefano Bonifazi [this message]
2011-01-24 21:21 ` Mike Frysinger
2011-01-24 21:52 ` Stefano Bonifazi
2011-01-24 22:11 ` Mike Frysinger
2011-01-24 22:24 ` Stefano Bonifazi
2011-01-24 22:34 ` Mike Frysinger
2011-01-25 0:06 ` Mike Frysinger
2011-01-25 0:18 ` Mike Frysinger
2011-01-25 8:49 ` Stefano Bonifazi
2011-01-25 8:26 ` Stefano Bonifazi
2011-01-24 19:46 ` Richard Henderson
2011-01-24 21:44 ` Stefano Bonifazi
2011-01-24 23:32 ` Mike Frysinger
2011-01-25 8:25 ` Stefano Bonifazi
2011-01-25 1:36 ` Richard Henderson
2011-01-25 8:47 ` Stefano Bonifazi
2011-01-25 8:53 ` Mike Frysinger
2011-01-25 9:58 ` Stefano Bonifazi
2011-01-25 10:47 ` Stefano Bonifazi
2011-01-25 16:22 ` Richard Henderson
2011-01-25 19:03 ` Stefano Bonifazi
2011-01-25 11:06 ` Stefano Bonifazi
2011-01-25 16:26 ` Richard Henderson
2011-01-25 19:49 ` Stefano Bonifazi
2011-01-25 20:53 ` Lluís
2011-01-26 11:07 ` Stefano Bonifazi
2011-01-26 15:38 ` Richard Henderson
2011-01-26 17:44 ` Stefano Bonifazi
2011-01-26 20:17 ` Lluís
2011-01-26 20:19 ` Richard Henderson
2011-01-26 20:33 ` Stefano Bonifazi
2011-01-26 20:36 ` Lluís
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