From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Ingo Molnar <mingo@redhat.com>, Vojtech Pavlik <vojtech@suse.cz>,
Jiri Kosina <jkosina@suse.cz>, Jiri Slaby <jslaby@suse.cz>,
Steven Rostedt <rostedt@goodmis.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] kprobes: introduce ARCH_HANDLES_KPROBES_ON_FTRACE
Date: Mon, 20 Oct 2014 10:55:30 +0900 [thread overview]
Message-ID: <54446B92.1040507@hitachi.com> (raw)
In-Reply-To: <1413387978-984-2-git-send-email-heiko.carstens@de.ibm.com>
(2014/10/16 0:46), Heiko Carstens wrote:
> Allow architectures to implement handling of kprobes on function
> tracer call sites on their own, without depending on common code.
>
> This patch removes the kprobes check if a kprobe is being placed
> on a function tracer call site and therefore gives full responsibility
> of handling this correctly to the architecture.
>
> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> ---
> arch/Kconfig | 8 ++++++++
> kernel/kprobes.c | 3 ++-
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 05d7a8a458d5..e1a8e0edf03f 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -85,6 +85,14 @@ config KPROBES_ON_FTRACE
> passing of pt_regs to function tracing, then kprobes can
> optimize on top of function tracing.
>
> +config ARCH_HANDLES_KPROBES_ON_FTRACE
> + def_bool n
> + help
> + If an architecture can handle kprobes on function tracer call
> + sites on own, then this option should be selected. This option
> + removes the check which otherwise prevents to set kprobes on
> + function tracer call sites.
> +
> config UPROBES
> def_bool n
> select PERCPU_RWSEM
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 3995f546d0f3..4cc48aa67635 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1428,7 +1428,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
> return -EILSEQ;
> p->flags |= KPROBE_FLAG_FTRACE;
> #else /* !CONFIG_KPROBES_ON_FTRACE */
> - return -EINVAL;
> + if (!IS_ENABLED(CONFIG_ARCH_HANDLES_KPROBES_ON_FTRACE))
> + return -EINVAL;
> #endif
> }
Hmm, this looks a bit not straight. Maybe we'd better introduce a local
check_ftrace_location() function which always returns 0 if
CONFIG_ARCH_HANDLES_KPROBES_ON_FTRACE(with a comment! :)) as below.
int check_ftrace_location(kp)
{
unsigned long ftrace_address;
/* If an architecture handles kprobes on ftrace, we don't check it */
if (IS_ENABLED(CONFIG_ARCH_HANDLES_KPROBES_ON_FTRACE))
return 0;
...
}
Thank you,
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2014-10-20 1:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-15 15:46 [PATCH 0/2] s390 vs. kprobes on ftrace Heiko Carstens
2014-10-15 15:46 ` [PATCH 1/2] kprobes: introduce ARCH_HANDLES_KPROBES_ON_FTRACE Heiko Carstens
2014-10-20 1:55 ` Masami Hiramatsu [this message]
2014-10-20 18:53 ` Steven Rostedt
2014-10-21 1:51 ` Masami Hiramatsu
2014-10-15 15:46 ` [PATCH 2/2] s390/ftrace,kprobes: allow to patch first instruction Heiko Carstens
2014-10-16 5:49 ` [PATCH 0/2] s390 vs. kprobes on ftrace Masami Hiramatsu
2014-10-16 10:57 ` Heiko Carstens
2014-10-21 9:37 ` Masami Hiramatsu
2014-10-17 8:19 ` Heiko Carstens
2014-10-17 8:28 ` Heiko Carstens
2014-10-20 2:02 ` Masami Hiramatsu
2014-10-20 6:41 ` Heiko Carstens
2014-10-17 8:21 ` Heiko Carstens
2014-10-20 1:31 ` Masami Hiramatsu
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