On Wed, Dec 20, 2006 at 03:21:53AM -0800, Jeremy Fitzhardinge wrote:
> "walt" <[EMAIL PROTECTED]> 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.
Regards,
Frederik
Signed-off-by: Frederik Deweerdt <[EMAIL PROTECTED]>
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)
{
-
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