From: Mike Grundy <grundym@us.ibm.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>,
Jan Glauber <jan.glauber@de.ibm.com>,
linux-kernel@vger.kernel.org, systemtap@sources.redhat.com
Subject: Re: [PATCH] kprobes for s390 architecture
Date: Fri, 7 Jul 2006 13:23:33 -0400 [thread overview]
Message-ID: <20060707172333.GA12068@localhost.localdomain> (raw)
In-Reply-To: <20060628055857.GA9452@osiris.boeblingen.de.ibm.com>
On Wed, Jun 28, 2006 at 07:58:57AM +0200, Heiko Carstens wrote:
> On Tue, Jun 27, 2006 at 05:23:09PM +0200, Martin Schwidefsky wrote:
> > On Sat, 2006-06-24 at 13:36 +0200, Heiko Carstens wrote:
> > > Just do a compare and swap operation on the instruction you want to replace,
> > > then do an smp_call_function() with the wait parameter set to 1 and passing
> > > a pointer to a function that does nothing but return.
> > Not good enough. An instruction can be fetched multiple times for a
> > single execution (see the other mail). So you have a half executed
> > instruction, the cache line is invalidated, a new instruction is written
> > and the cache line is recreated to finished the half executed
> > instruction. That can easiliy happen on millicoded instructions.
>
> Yes, looks like I was too optimistic. Seems like we really have to go for
> stop_machine_run() unless somebody comes up with a better idea...
ok, I tried, but my "better ideas" made things worse. stop_machine_run() wins:
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
unsigned long status = kcb->kprobe_status;
struct ins_replace_args args;
args.ptr = p->addr;
args.old = p->opcode;
args.new = BREAKPOINT_INSTRUCTION;
kcb->kprobe_status = KPROBE_SWAP_INST;
stop_machine_run(swap_instruction, &args, NR_CPUS);
kcb->kprobe_status = status;
}
It works, and I guess at this point is the only way to do it. I'll send out a
full patch with this and the other cleanups later.
Mike
next prev parent reply other threads:[~2006-07-07 17:23 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20060623150344.GL9446@osiris.boeblingen.de.ibm.com>
2006-06-23 22:53 ` [heiko.carstens@de.ibm.com: Re: [PATCH] kprobes for s390 architecture] Michael Grundy
2006-06-23 22:21 ` [PATCH] kprobes for s390 architecture Heiko Carstens
2006-06-24 11:36 ` Heiko Carstens
2006-06-24 12:15 ` Heiko Carstens
2006-06-25 13:31 ` Mike Grundy
2006-06-26 8:09 ` Heiko Carstens
2006-06-26 10:49 ` Mike Grundy
2006-06-26 11:19 ` Heiko Carstens
2006-06-27 15:23 ` Martin Schwidefsky
2006-06-28 5:58 ` Heiko Carstens
2006-07-07 17:23 ` Mike Grundy [this message]
2006-07-07 17:25 ` Heiko Carstens
2006-07-08 18:54 ` Mike Grundy
2006-07-08 19:58 ` Mike Grundy
2006-07-10 9:28 ` Heiko Carstens
2006-07-10 22:20 ` Mike Grundy
2006-07-11 13:54 ` Mike Grundy
2006-07-11 14:13 ` Martin Schwidefsky
2006-06-12 13:15 Mike Grundy
2006-06-12 19:40 ` Martin Schwidefsky
2006-06-21 4:28 ` Mike Grundy
2006-06-21 16:38 ` Martin Schwidefsky
2006-06-21 17:15 ` Mike Grundy
2006-06-27 11:56 ` Martin Schwidefsky
2006-06-21 17:34 ` Mike Grundy
2006-06-22 11:28 ` Jan Glauber
2006-06-22 16:36 ` Mike Grundy
2006-06-23 8:50 ` Jan Glauber
2006-06-23 14:38 ` Heiko Carstens
2006-06-22 1:38 ` Mike Grundy
2006-06-21 9:40 ` Jan Glauber
2006-06-21 16:23 ` Jan Glauber
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