Doug / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit bac821a6e3404330d509fd3a245bf7701f210c7c

Authored by Steven Rostedt
Committed by Benjamin Herrenschmidt
1 parent e5ae3cdfd5
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

powerpc/ftrace: Trace function graph entry before updating index 

As Colin Cross ported my x86 change to ARM, he also pointed out that
powerpc is also behind in this fix.

The commit 722b3c746953 "ftrace/graph: Trace function entry before
updating index" fixes an issue with function graph tracing for x86,
where if the called entry function decides not to trace interrupts, it
can fail the check if an interrupt comes in just after the
curr_ret_stack is updated.

The solution is to call the entry function first, then update the
curr_ret_stack if the entry function wants to be traced.

Cc: Colin Cross <ccross@android.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Showing 1 changed file with 5 additions and 6 deletions Side-by-side Diff

arch/powerpc/kernel/ftrace.c
Diff comments   View file @ bac821a
... ... @@ -630,18 +630,17 @@
630 630 return;
631 631 }
632 632  
633   - if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY) {
634   - *parent = old;
635   - return;
636   - }
637   -
638 633 trace.func = self_addr;
  634 + trace.depth = current->curr_ret_stack + 1;
639 635  
640 636 /* Only trace if the calling function expects to */
641 637 if (!ftrace_graph_entry(&trace)) {
642   - current->curr_ret_stack--;
643 638 *parent = old;
  639 + return;
644 640 }
  641 +
  642 + if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY)
  643 + *parent = old;
645 644 }
646 645 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
647 646