From owner-freebsd-hackers@FreeBSD.ORG  Mon Apr 13 00:09:48 2015
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In-Reply-To: <alpine.BSF.2.20.1504122119100.18539@laptop.wojtek.intra>
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Date: Mon, 13 Apr 2015 02:02:51 +0200
Message-ID: <CAPQ4fft+Ut-ZiNM9=q3V-G9Pm3ppzqZGKJ0JS3Sw-i7mQRhUTQ@mail.gmail.com>
Subject: Re: stack pointer on 64-bit architecture
From: Oliver Pinter <oliver.pinter@hardenedbsd.org>
To: Wojciech Puchar <wojtek@puchar.net>
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The stack address come from this code:

https://github.com/freebsd/freebsd/blob/master/sys/kern/kern_exec.c#L1065
where sv->sv_usrstack depends on architecture and on image activator.

and this the other place, where the stack address is "hardcoded":
https://github.com/freebsd/freebsd/blob/master/sys/kern/kern_exec.c#L1240


Just grep against sv_psstrings and sv_usrstack to see what depend on
current hardcoded stack address. ;)

On Sun, Apr 12, 2015 at 9:19 PM, Wojciech Puchar <wojtek@puchar.net> wrote:
> what decides where stack is located when process starts on 64-bit machine
> (x86-64)?
>
> it starts normally below 0x0000800000000000
>
> can starting address be set to different (smaller) value?
>
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