[OSy] Problem s procesy

[Miloslav Beno]

Pomohlo to. Velmi dekuji vsem, kteri poradili. 

-----Original Message-----
From: osy-bounces at dsrg.mff.cuni.cz [mailto:osy-bounces at dsrg.mff.cuni.cz] On Behalf Of David Matousek
Sent: Thursday, December 27, 2007 10:32 PM
To: Operating Systems Course
Subject: Re: [OSy] Problem s procesy

Zdravim,

stranka 68 manualu rika

The processor operates in User mode when the Status register contains the
following bit-values:
• KSU bits = 102
• EXL = 0
• ERL = 0
In conjunction with these bits, the UX bit in the Status register selects
between 32- or 64-bit User mode addressing as follows:
• when UX = 0, 32-bit useg space is selected and TLB misses are
handled by the 32-bit TLB refill exception handler
• when UX = 1, 64-bit xuseg space is selected and TLB misses are
handled by the 64-bit XTLB refill exception handler

Melo by pomoct ...

DM


Miloslav Beno wrote:
> Dobry vecer,
> 
> Umistili jsme stack o jednu stranku dale a zacalo to fungovat. Nyni vse bezi, ale bohuzel se vyskytl problem, ze ackoliv nastavujeme status registr takto: 
> 
> #define USER_THREAD_STATUS	\
> (				\
> 	  cp0_status_ux_mask 	\
> 	| cp0_status_ie_mask | cp0_status_im_mask	\
> 	| cp0_status_cu0_mask	\
> )
> 
> 
> 
> t->kernel_stack_top [OFFSET_STATUS / sizeof (int)] = USER_THREAD_STATUS;
> 
> Tak i presto funguji instrukce, ktere by mely fungovat pouze v kernel modu.
> 
> Dekujeme
> 
> -----Original Message-----
> From: osy-bounces at dsrg.mff.cuni.cz [mailto:osy-bounces at dsrg.mff.cuni.cz] On Behalf Of Martin Decky
> Sent: Thursday, December 27, 2007 6:44 PM
> To: Operating Systems Course
> Subject: Re: [OSy] Problem s procesy
> 
>> Vytvarime thread stejnym postupem jako kernel thread, ale vrchol zasobniku
>> je v USEGu a status registr je inicializovany jako user mode. GP registr a
>> RET registr ma hodnotu 0x0.
>> Pri prepnuti na toto vlakno se program pokousi sahnout na adresu 0xffffff74.
> 
> A muzete zjistit nejak presneji, co (tedy jake instrukce) sahnou na
> tuhle adresu? Je to hned prvni instrukce noveho vlakna, nebo se to stane
> az casem.
> 
> Mohlo by to byt podteceni zasobniku, i kdyz trochu netradicni. Jestli
> jsem dobre pochopil, co pisete, tak nemate zasobniky na konci
> uzivatelskeho adresoveho prostoru, ale pobliz zacatku. Pokud mezi
> zasobnikem a obrazem procesu nemate zadnou ochranou stranku, tak je
> mozne, ze zasobnik podtece pod adresu 0.
> 
> Alternativne to samozrejme muze byt jakykoliv zbloudily pristup do
> pameti, napriklad neco, co indexuje o -139 bytu vuci adrese 0 apod.
> 
> 
> M.D.
> 
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