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Re: [PATCH] acpi: fix incompatibility with mcount-based function graph tracing

From Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] acpi: fix incompatibility with mcount-based function graph tracing
Date 2017-03-27 16:20 +0200
Message-ID <tpDEZ-QR-17@gated-at.bofh.it> (permalink)
References <tlEzD-80N-5@gated-at.bofh.it> <toBYD-5oX-19@gated-at.bofh.it> <toCrE-5z0-13@gated-at.bofh.it> <toTVw-1li-3@gated-at.bofh.it>
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On Sat, Mar 25, 2017 at 02:20:11PM +0100, Rafael J. Wysocki wrote:
> On Friday, March 24, 2017 02:41:14 PM Steven Rostedt wrote:
> > On Fri, 24 Mar 2017 13:12:54 -0500
> > Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > 
> > 
> > > Instead I was able to "fix" it by ignoring ftrace calls in real mode:
> > > 
> > > -----
> > > index 8f3d9cf..5c0d0c6 100644
> > > --- a/arch/x86/kernel/ftrace.c
> > > +++ b/arch/x86/kernel/ftrace.c
> > > @@ -983,6 +983,9 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
> > >  	unsigned long return_hooker = (unsigned long)
> > >  				&return_to_handler;
> > >  
> > > +	if (__builtin_return_address(0) < TASK_SIZE_MAX)
> > > +		return;
> > > +
> > >  	if (unlikely(ftrace_graph_is_dead()))
> > >  		return;
> > > ---------------
> > > 
> > > I'm not sure what the best fix should really be.  A few ideas off the
> > > top of my head:
> > > 
> > > - A real mode check similar to the above (except it should probably be
> > >   more precise)
> > 
> > The real mode check hack may be good enough for now. Make sure that
> > it's commented well.
> 
> Agreed.

Just to clarify, there are two bugs related to function graph tracing
and suspend/resume.  The original patch in this thread (which removes
'-Os' from the acpi Makefile) is still needed.

-- 
Josh

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Thread

[PATCH] acpi: fix incompatibility with mcount-based function graph tracing Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-16 15:30 +0100
  Re: [PATCH] acpi: fix incompatibility with mcount-based function  graph tracing Steven Rostedt <rostedt@goodmis.org> - 2017-03-16 15:50 +0100
  Re: [PATCH] acpi: fix incompatibility with mcount-based function  graph tracing Paul Menzel <pmenzel@molgen.mpg.de> - 2017-03-21 21:50 +0100
    Re: [PATCH] acpi: fix incompatibility with mcount-based function  graph tracing Paul Menzel <pmenzel@molgen.mpg.de> - 2017-03-22 01:10 +0100
    Re: [PATCH] acpi: fix incompatibility with mcount-based function  graph tracing Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-24 19:20 +0100
      Re: [PATCH] acpi: fix incompatibility with mcount-based function  graph tracing Steven Rostedt <rostedt@goodmis.org> - 2017-03-24 19:50 +0100
        Re: [PATCH] acpi: fix incompatibility with mcount-based function graph tracing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-03-25 14:30 +0100
          Re: [PATCH] acpi: fix incompatibility with mcount-based function  graph tracing Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-27 16:20 +0200
            [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing and  suspend-to-ram Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-27 17:00 +0200
              Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Paul Menzel <pmenzel@molgen.mpg.de> - 2017-03-27 17:10 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Steven Rostedt <rostedt@goodmis.org> - 2017-03-27 17:30 +0200
                [PATCH v2] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-27 17:30 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Paul Menzel <pmenzel@molgen.mpg.de> - 2017-03-28 12:00 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Steven Rostedt <rostedt@goodmis.org> - 2017-03-28 17:50 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-28 18:00 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing and suspend-to-ram "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-03-28 23:20 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing  and suspend-to-ram Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-28 23:50 +0200
                Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing and suspend-to-ram "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-03-29 00:00 +0200
            Re: [PATCH] acpi: fix incompatibility with mcount-based function graph tracing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-03-27 19:10 +0200

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