Re: [PATCH] tracing: Fix printing ptrs in preempt/irq enable/disable events

Antonio Borneo
2020-01-07T09:23:28Z

On Mon, 2019-12-23 at 15:13 -0500, Steven Rostedt wrote:
> On Sat, 21 Dec 2019 18:47:41 -0500
> Joel Fernandes <joel@joelfernandes.org> wrote:
>
> > On Wed, Dec 04, 2019 at 09:21:15AM -0500, Steven Rostedt wrote:
> > > Joel,
> > >
> > > Any comments on this patch?
> >
> > Steve, it looks like this issue happens with trace-cmd not knowing what
> > _stext is. If I do cat trace_pipe , then I don't see the issue as _stext is
> > looked up correctly but the reporter of the bug is using trace-cmd. Is there
> > a way to solve this within trace-cmd? Not knowing much about trace-cmd
> > internals, I will have to defer to you on this though..
> >
> > Other than this, I need to make the offset to _stext as s32 instead of u32
> > type so that the problem of the symbol location being before _stext does not
> > cause overflow.
> >
> > Lastly, I am not super convinced that we need to store the full pointer just
> > to handle a case where the offset of the symbol might be more than +-2G from
> > _stext. Once we see such issue, then we can handle it. But right now the size
> > of the trace buffer is utilized better by just storing the offset IMHO.
> >
>
> Does this fix it for you?
>
> -- Steve
>

Steve,

this patch fixes the issue for me, thanks!
Tested-by: Antonio Borneo <antonio.borneo@st.com>

There are other cases where the trace buffer is under stress, e.g. during function tracing.
Would it be useful to only store the offset in such cases too?

Regards,
Antonio