arm64: Don't trace __switch_to if function graph tracer is enabled

Function graph tracer shows negative time (wrap around) when tracing
__switch_to if the nosleep-time trace option is enabled.

Time compensation for nosleep-time is done by an ftrace probe on
sched_switch. This doesn't work well for the following events (with
letters representing timestamps):
A - sched switch probe called for task T switch out
B - __switch_to calltime is recorded
C - sched_switch probe called for task T switch in
D - __switch_to rettime is recorded

If C - A > D - B, then we end up over compensating for the time spent in
__switch_to giving rise to negative times in the trace output.

On x86, __switch_to is not traced if function graph tracer is enabled.
Do the same for arm64 as well.

Cc: Todd Kjos <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Rutland <[email protected]>
Signed-off-by: Joel Fernandes <[email protected]>
Signed-off-by: Will Deacon <[email protected]>

0 files changed, 0 insertions, 0 deletions