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Date:      Mon, 23 Dec 2002 10:06:44 +0100
From:      Aurelien Nephtali <aurelien.nephtali@wanadoo.fr>
To:        John <jwd@bsdwins.com>
Cc:        hackers@freebsd.org
Subject:   Re: Accessing trap frame from userland?
Message-ID:  <20021223090644.GA615@nebula.wanadoo.fr>
In-Reply-To: <20021223025159.GA27162@BSDWins.Com>
References:  <20021222183400.GA77934@nebula.wanadoo.fr> <20021223025159.GA27162@BSDWins.Com>

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On Sun, Dec 22, 2002 at 09:51:59PM -0500, John wrote:
> After the interupt (from the child issuing a PT_TRACE_ME
> ptrace() call, you need to call i386_clr_watch().
>=20
> At this point, you can single step the process using
> ptrace(PT_STEP), or by calling i386_set_watch() with
> a new address (type DBREG_DR7_EXEC), and then calling
> ptrace(PT_CONTINUE). Note: this all assumes you are
> getting and putting the debug registers correctly.
>=20
> Hope this helps. It's been a while since I've looked
> at this stuff... somewhere I've got a sample program
> that traces dynamic image loads. If I can find it I'll
> hang it off website.
>=20
> -john

Mmh, that's the method I try to avoid :), according to me it's 'ugly' :) si=
nce
that need a big if() hack to handle the break issuing from a PT_STEP without
mixing it with an user wanted breakpoint. I'd rather trying to access the
'trap frame' if it's possible, otherwise I'll do the single-step-ugly-hack
method :)

-- Aurelien

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