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From: Mike Frysinger <vapier@gentoo.org>
Date: Thu, 26 May 2011 01:25:48 -0400
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Subject: Re: [PATCH -tip ] [BUGFIX]tracing/kprobes: Fix kprobe-tracer to
 support stack trace
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Frederic Weisbecker <fweisbec@gmail.com>, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@redhat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        yrl.pp-manager.tt@hitachi.com, Russell King <rmk@arm.linux.org.uk>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>
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On Wed, May 25, 2011 at 22:07, Steven Rostedt wrote:
> On Thu, 2011-05-12 at 19:22 +0900, Masami Hiramatsu wrote:
>> Fix to support kernel stack trace correctly on kprobe-tracer.
>> Since the execution path of kprobe-based dynamic events is different
>> from other tracepoint-based events, normal ftrace_trace_stack() doesn't
>> work correctly. To fix that, this introduces ftrace_trace_stack_regs()
>> which traces stack via pt_regs instead of current stack register.
>
> I'm working to get a "fix" patch set push out, and I included this
> patch. But when I ran it on my arch test (compiling on other archs),
> this patch broke the following:
>
>  arm, blackfin, powerpc, s390.
>
> (Note, due to other bugs, UML and mips does not build to test)
>
> The problem is that these archs do not implement a:
>
>  save_stack_trace_regs() function.

i think only x86 implements that func ?  and its stacktrace.c just
seems to beg for generalization ...
-mike