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From: Kevin Lawton <kevinlawton2001@yahoo.com>
To: linux-kernel@vger.kernel.org
Subject: Possible bug in arch/i386/kernel/process.c for reloading of debug registers (DRx)?
Date: Mon, 3 Feb 2003 15:51:40 -0800 (PST)	[thread overview]
Message-ID: <20030203235140.10443.qmail@web80304.mail.yahoo.com> (raw)

I was scanning through the source and noticed the lines below.
Should the code below, be reloading at least the local bits of
DR7 if the current DR7 value != 0?  From a quick glance, it
looks like only if the next task's DR7 value is non-zero,
that DR7 is reloaded.  I'm wondering if this would leave
a new task to receive "local" debug events for the previous
task if prev->DR7!=0 && next->DR7==0.

-Kevin


linux-2.5.59: arch/i386/kernel/process.c: line 462+:

  /*
   * Now maybe reload the debug registers
   */
  if (unlikely(next->debugreg[7])) {
    loaddebug(next, 0);
    loaddebug(next, 1);
    loaddebug(next, 2);
    loaddebug(next, 3);
    /* no 4 and 5 */
    loaddebug(next, 6);
    loaddebug(next, 7);
  }

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             reply	other threads:[~2003-02-03 23:42 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-02-03 23:51 Kevin Lawton [this message]
     [not found] <20030203235140.10443.qmail@web80304.mail.yahoo.com.suse.lists.linux.kernel>
2003-02-04  0:39 ` Andi Kleen
2003-02-07 16:33   ` Pavel Machek
2003-02-08 17:22     ` Andi Kleen
2003-02-08 19:31       ` Jamie Lokier
2003-02-09  0:56         ` Andi Kleen

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