Re: Linux 2.4.17 bug, mmap of /dev/mem

5 messages, 4 authors, 2002-02-28 · open the first message on its own page

Re: Linux 2.4.17 bug, mmap of /dev/mem

From: David Ashley <hidden>
Date: 2002-02-27 21:04:37

I've traced the problem down to arch/ppc/mm/hashtable.S. When
there is a page fault, the function hash_page gets called. This does
some hashing and writes the hash values into a table located at
0xc0180000. That is the default value, before patching. These writes are
what is corrupting the linux kernel, because they are on top of linux
itself.

In arch/ppc/mm/ppc_mmu.c the function MMU_init_hw is called, but
since the 8260 doesn't have the CPU_FTR_HPTE_TABLE feature, the
hash table is never allocated and the hash_page_patch_* never get updated.

Turning on the CPU_FTR_HPTE_TABLE for the 8260 doesn't fix the problem.

I'm out of my depth here. This is a bug in linux, I know that much. But I
don't know what is supposed to happen during a page fault. So I need help
in resolving this.

Thanks--
Dave

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Re: Linux 2.4.17 bug, mmap of /dev/mem

From: Dan Malek <hidden>
Date: 2002-02-27 21:06:30

David Ashley wrote:
I've traced the problem down to arch/ppc/mm/hashtable.S. When
there is a page fault, the function hash_page gets called.
In the case of a 603 core, hash_page is called for DSI (Data Access)
faults.  However, if the feature indicates there is no HPTE, the
hash_page function is patched to simply return.  You can't look at
the code in hashtable.S and know how it is going to work for a particular
implementation because it is patched at initialization to change
it's behavior.
.....This does
some hashing and writes the hash values into a table located at
0xc0180000.
When your kernel boots, does it print a message to indicate it has allocated
a hash table?
In arch/ppc/mm/ppc_mmu.c the function MMU_init_hw is called, but
since the 8260 doesn't have the CPU_FTR_HPTE_TABLE feature, the
hash table is never allocated and the hash_page_patch_* never get updated.

Oh, I just looked at a variety of different versions back to 2.4.11, and it
is patched just as I described above.


	-- Dan


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gdbserver ppc8xx

From: Owen Green <hidden>
Date: 2002-02-27 21:47:49

Hi all,

could anyone tell me where can I find a gdbserver that
works with mpc8xx processor? Where can I find sources
that compiles for 8xx?

I have already tried with mvista HHL2.0 Journeyman
edition but I got something like:
#gdbserver :7777 /bin/test
Process /bin/test created; pid = 48
getprotobyname:Sucess.
Exiting
#
What could be wrong? Any tip will be very appreciate.

Thanks in advance,

   Owen.


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Re: gdbserver ppc8xx

From: Christian Pellegrin <hidden>
Date: 2002-02-28 08:01:37

On Wed, 27 Feb 2002, Owen Green wrote:
Hi all,

could anyone tell me where can I find a gdbserver that
works with mpc8xx processor? Where can I find sources
that compiles for 8xx?

I have already tried with mvista HHL2.0 Journeyman
edition but I got something like:
#gdbserver :7777 /bin/test
Process /bin/test created; pid = 48
getprotobyname:Sucess.
Exiting
#
What could be wrong? Any tip will be very appreciate.
just copy /etc/protocols from whatever distro you like. Bye!


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Re: gdbserver ppc8xx

From: Owen Green <hidden>
Date: 2002-02-28 13:50:01

--- Christian Pellegrin <chri@infis.univ.trieste.it>
wrote:
On Wed, 27 Feb 2002, Owen Green wrote:
quoted
edition but I got something like:
#gdbserver :7777 /bin/test
Process /bin/test created; pid = 48
getprotobyname:Sucess.
Exiting
#
just copy /etc/protocols from whatever distro you
like. Bye!
This did not work, I got the getprotobyname: Sucess,
what means my /etc/protocols have the entry for tcp.
Thanks anyway.


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