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Date: Wed, 20 Dec 2006 14:02:15 -0500 From: "Andrew J. Barr" <andrew.james.barr@...il.com> To: Frederik Deweerdt <deweerdt@...e.fr> Cc: Jeremy Fitzhardinge <jeremy@...p.org>, Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org, Jan Beulich <jbeulich@...ell.com>, Andi Kleen <ak@...e.de>, "Eric W. Biederman" <ebiederm@...ssion.com>, walt <w41ter@...il.com> Subject: Re: [-mm patch] ptrace: Fix EFL_OFFSET value according to i386 pda changes (was Re: BUG on 2.6.20-rc1 when using gdb) On Wed, 2006-12-20 at 18:35 +0000, Frederik Deweerdt wrote: > On Wed, Dec 20, 2006 at 03:21:53AM -0800, Jeremy Fitzhardinge wrote: > > "walt" <w41ter@...il.com> reported a similar problem which he bisected > > down to the PDA changeset which touches ptrace > > (66e10a44d724f1464b5e8b5a3eae1e2cbbc2cca6). I haven't managed to repo > > the problem, but I guess there's something nasty going on in ptrace - > > maybe its screwing up eflags on the stack or something. Need to > > double-check all the conversions from kernel<->usermode registers. Hm, > > wonder if its fixed with the %gs->%fs conversion patch applied? > > > Hi Jeremy, > > Same problems here with 2.6.20-rc1-mm1 (ie with the %gs->%fs patch). > It seems to me that the problem comes from the EFL_OFFSET no longer > beeing accurate. > The following patch fixes the problem for me. Me too. Thanks. Andrew > Regards, > Frederik > > Signed-off-by: Frederik Deweerdt <frederik.deweerdt@...il.com> > > diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c > index 7f7d830..00d8a5a 100644 > --- a/arch/i386/kernel/ptrace.c > +++ b/arch/i386/kernel/ptrace.c > @@ -45,7 +45,7 @@ > /* > * Offset of eflags on child stack.. > */ > -#define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs)) > +#define EFL_OFFSET ((EFL-1)*4-sizeof(struct pt_regs)) > > static inline struct pt_regs *get_child_regs(struct task_struct *task) > { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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