On Fri, 11 Oct 2013 09:21:56 +0200
Heiko Carstens <heiko.carst...@de.ibm.com> wrote:
>
> Steven Rostedt noted that s390 is the only architecture which calls
> ftrace_push_return_trace() before ftrace_graph_entry() and therefore has
I don't know if s390 is the only arch. I didn't finish reading all the
arch specific code to make sure.
> the small advantage that trace.depth gets initialized automatically.
>
> However this small advantage isn't worth the difference and possible subtle
> breakage that may result from this.
> So change s390 to have the same function call order like all other
> architectures: first ftrace_graph_entry(), then ftrace_push_return_trace()
>
> Reported-by: Steven Rostedt <rost...@goodmis.org>
> Signed-off-by: Heiko Carstens <heiko.carst...@de.ibm.com>
> ---
> arch/s390/kernel/ftrace.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
> index 1014ad5..224db03 100644
> --- a/arch/s390/kernel/ftrace.c
> +++ b/arch/s390/kernel/ftrace.c
> @@ -151,14 +151,13 @@ unsigned long __kprobes prepare_ftrace_return(unsigned
> long parent,
> if (unlikely(atomic_read(¤t->tracing_graph_pause)))
> goto out;
> ip = (ip & PSW_ADDR_INSN) - MCOUNT_INSN_SIZE;
> - if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
> - goto out;
> trace.func = ip;
> + trace.depth = current->curr_ret_stack + 1;
> /* Only trace if the calling function expects to. */
> - if (!ftrace_graph_entry(&trace)) {
> - current->curr_ret_stack--;
> + if (!ftrace_graph_entry(&trace))
> + goto out;
> + if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
> goto out;
> - }
Hmm, if this code is so identical among the archs, I may create a
generic inline function to do the work. That way any change to the flow
can be done for all archs in one place.
Thanks!
-- Steve
> parent = (unsigned long) return_to_handler;
> out:
> return parent;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
