From: "Jan Beulich" <jbeulich@novell.com>
To: Keir Fraser <keir@xensource.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: trap bounce flags
Date: Wed, 25 Apr 2007 12:11:01 +0100 [thread overview]
Message-ID: <462F5365.76E4.0078.0@novell.com> (raw)
In-Reply-To: <C254F25B.DD11%keir@xensource.com>
>>> Keir Fraser <keir@xensource.com> 25.04.07 12:56 >>>
>On 25/4/07 11:41, "Keir Fraser" <keir@xensource.com> wrote:
>
>> Attached is my own proposed patch which I think cleans up all the issues.
>> Checking just flags in asm and keeping the null-bounce check in
>> init_int80_direct_trap() seems fine to me.
>
>The change of a movw $0 to a movb $TBF_EXCEPTION in that patch is wrong, by
>the way. Should be movb $0.
Which means there's not really a dependency on this being non-zero...
The patch looks otherwise okay to me, though I think there's one more
issue here: There's another suffix-less instruction (updating UREGS_rip
in int80_slow_path) - this must be a subq, and it must imply that no 32-bit
guest places an int $0x80 at 0xfffffffe.
And my patch has a not directly related adjustment removing the
movl $TRAP_syscall,UREGS_entry_vector+8(%rsp)
close to the end of compat_create_bounce_frame, as this is meaningless
here.
Jan
next prev parent reply other threads:[~2007-04-25 11:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-25 9:56 trap bounce flags Jan Beulich
2007-04-25 10:10 ` Keir Fraser
2007-04-25 10:16 ` Keir Fraser
2007-04-25 10:33 ` Jan Beulich
2007-04-25 10:41 ` Keir Fraser
2007-04-25 10:56 ` Keir Fraser
2007-04-25 11:11 ` Jan Beulich [this message]
2007-04-25 11:26 ` Keir Fraser
2007-04-25 11:48 ` Jan Beulich
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