FUNCTION_GRAPH_TRACER + UNWINDER_FRAME_POINTER broken on arm

[Uwe Kleine-König]

Hello,

With FUNCTION_GRAPH_TRACER=y and CONFIG_UNWINDER_FRAME_POINTER=y I
experience the following issue:

	# echo function_graph > /sys/kernel/tracing/current_tracer
	[  303.812295] Kernel panic - not syncing: �e
	[  303.816738] ---[ end Kernel panic - not syncing: �e ]---

This reproduces reliably on v6.9 (on an i.MX25 based machine).

Bisection points on v5.18-rc1~150^2~7^2~6 ("ARM: ftrace: enable
HAVE_FUNCTION_GRAPH_FP_TEST"). 

#regzbot introduced: 953f534a7ed6b725d4f101d2949393acc9262880

I didn't try to understand the issue yet, but just disabled
UNWINDER_FRAME_POINTER for now, which makes the problem disappear.
Disabling CONFIG_DYNAMIC_FTRACE is another option to work around the
problem.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |
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