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From: Jun Sun <jsun@mvista.com>
To: "Steven J. Hill" <sjhill@realitydiluted.com>
Cc: linux-mips@linux-mips.org, jsun@mvista.com
Subject: Re: Improper handling of unaligned user address access?
Date: Mon, 3 Mar 2003 17:41:53 -0800	[thread overview]
Message-ID: <20030303174153.B19572@mvista.com> (raw)
In-Reply-To: <3E63EFDC.6090605@realitydiluted.com>; from sjhill@realitydiluted.com on Mon, Mar 03, 2003 at 06:14:20PM -0600

On Mon, Mar 03, 2003 at 06:14:20PM -0600, Steven J. Hill wrote:
> The first thing I tried to fix this issue was to use the
> 'memcpy.S' file from 2.4.7 and that actually worked, but
> that was a step backwards. It was much simpler to just
> add a 'nop' after the offending branch instruction. It
> fixes all of my problems with 'copy_from_user'. 

Adding 'nop' seems to be right.

> I do have one further question. In 'arch/mips/mm/fault.c'
> when we need to do a fixup:
> 
>     fixup = search_exception_table(regs->cp0_epc);
>
> Why do we not check to see if the EPC is a branch insn
> before looking in the exception table?
>

You must be looking at a different tree.  We do check epc
for branch instruction:

	fixup = search_exception_table(exception_epc(regs));

Jun

      reply	other threads:[~2003-03-04  1:42 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-03-03 19:48 Improper handling of unaligned user address access? Steven J. Hill
2003-03-03 21:22 ` Geert Uytterhoeven
2003-03-03 21:38   ` Mike Uhler
2003-03-03 21:38     ` Mike Uhler
2003-03-03 22:16     ` Steven J. Hill
2003-03-04  0:14 ` Steven J. Hill
2003-03-04  1:41   ` Jun Sun [this message]

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