From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Namhyung Kim <namhyung@kernel.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
williams@redhat.com,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 2/2] ftrace/x86/extable: Add is_ftrace_trampoline() function
Date: Wed, 19 Nov 2014 13:39:11 -0500 [thread overview]
Message-ID: <20141119133911.1b030287@gandalf.local.home> (raw)
In-Reply-To: <alpine.DEB.2.11.1411191928090.3909@nanos>
On Wed, 19 Nov 2014 19:29:25 +0100 (CET)
Thomas Gleixner <tglx@linutronix.de> wrote:
> On Wed, 19 Nov 2014, Steven Rostedt wrote:
> > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > Date: Tue, 18 Nov 2014 21:14:11 -0500
> > Subject: [PATCH] ftrace/x86/extable: Add is_ftrace_trampoline() function
> >
> > Stack traces that happen from function tracing check if the address
> > on the stack is a __kernel_text_address(). That is, is the address
> > kernel code. This calls core_kernel_text() which returns true
> > if the address is part of the builtin kernel code. It also calls
> > is_module_text_address() which returns true if the address belongs
> > to module code.
> >
> > But what is missing is ftrace dynamically allocated trampolines.
> > These trampolines are allocated for individual ftrace_ops that
> > call the ftrace_ops callback functions directly. But if they do a
> > stack trace, the code checking the stack wont detect them as they
> > are neither core kernel code nor module address space.
> >
> > Adding another field to ftrace_ops that also stores the size of
> > the trampoline assigned to it we can create a new function called
> > is_ftrace_trampoline() that returns true if the address is a
> > dynamically allocate ftrace trampoline. Note, it ignores trampolines
> > that are not dynamically allocated as they will return true with
> > the core_kernel_text() function.
> >
> > Link: http://lkml.kernel.org/r/20141119034829.497125839@goodmis.org
> >
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: "H. Peter Anvin" <hpa@zytor.com>
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
>
> Acked-by: Thomas Gleixner <tglx@linutronix.de>
Thanks!
-- Steve
prev parent reply other threads:[~2014-11-19 18:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-19 3:33 [PATCH 0/2] ftrace: Fix stack tracing issues Steven Rostedt
2014-11-19 3:33 ` [PATCH 1/2] ftrace/x86: Add frames pointers to trampoline as necessary Steven Rostedt
2014-11-19 18:26 ` Thomas Gleixner
2014-11-19 18:38 ` Steven Rostedt
2014-11-19 3:33 ` [PATCH 2/2] ftrace/x86/extable: Add is_ftrace_trampoline() function Steven Rostedt
2014-11-19 4:15 ` Steven Rostedt
2014-11-19 8:16 ` Namhyung Kim
2014-11-19 13:36 ` Steven Rostedt
2014-11-19 15:37 ` Steven Rostedt
2014-11-19 18:29 ` Thomas Gleixner
2014-11-19 18:39 ` Steven Rostedt [this message]
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