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Message-ID: <47384D34.6070000@redhat.com>
Date: Mon, 12 Nov 2007 07:55:16 -0500
From: Masami Hiramatsu <mhiramat@...hat.com>
To: Arjan van de Ven <arjan@...radead.org>
CC: linux-kernel@...r.kernel.org, tglx@...x.de, mingo@...e.hu,
hpa@...or.com, ananth@...ibm.com
Subject: Re: [patch] prepare kprobes code for x86 unification
Hi Arjan,
Arjan van de Ven wrote:
> From: Arjan van de Ven <arjan@...ux.intel.com>
> Subject: prepare kprobes code for x86 unification
>
> This patch is a first step towards unification of the kprobes
> infrastructure between 32 and 64 bit x86; the patch is mostly
> about removing spurious whitespace changes and about adding
> harmless includes and the like to make the 32/64 files more
> identical.
>
> Signed-off-by: Arjan van de Ven
I got a bug in this patch. In kprobes_64.c, Since this added __kprobes
to kretprobe_trampoline_holder(), the arch_init_kprobes() failed to
insert a kprobe into that function, and the initialization was failed.
This means that kprobe_exceptions_notify() was not registered to
die_notifier_chain. So, it caused a kernel crash.
> @@ -385,7 +428,7 @@ no_kprobe:
> * here. When a retprobed function returns, this probe is hit and
> * trampoline_probe_handler() runs, calling the kretprobe's handler.
> */
> - void kretprobe_trampoline_holder(void)
> + void __kprobes kretprobe_trampoline_holder(void)
> {
> asm volatile ( ".global kretprobe_trampoline\n"
> "kretprobe_trampoline: \n"
On i386, I introduced kretprobe-booster, which did not need to insert
a kprobe. Thus, I also added __kprobes to kretprobe_trampoline_holder()
on i386.
I think we can remove __kprobes from kretprobe_trampoline_holder()
in kprobes_32.c if you'd like to make the both same. However, it
is not safe. So we need a comment on top explaining why it does not
have that annotation and users must take care of it.
By the way, I'm porting boosters to x86-64 (and ia64). Since some parts
of that will be covered by this patch, I'd like to know your unification
plan.
Best regards,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@...hat.com, masami.hiramatsu.pt@...achi.com
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