[S390] ftrace: fix kernel stack backchain walking
authorHeiko Carstens <heiko.carstens@de.ibm.com>
Fri, 14 Nov 2008 17:18:05 +0000 (18:18 +0100)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>
Fri, 14 Nov 2008 17:18:53 +0000 (18:18 +0100)
commit50bec4ce5d36ebf96189dcc54e20c7fce4bf61bf
tree5f04e012e882ed15f9c7f1f45b0e9a27dd2656f5
parent632448f65001c4935ed0d3bb362017d773da2eca
[S390] ftrace: fix kernel stack backchain walking

With CONFIG_IRQSOFF_TRACER the trace_hardirqs_off() function includes
a call to __builtin_return_address(1). But we calltrace_hardirqs_off()
from early entry code. There we have just a single stack frame.
So this results in a kernel stack backchain walk that would walk beyond
the kernel stack. Following the NULL terminated backchain this results
in a lowcore read access.

To fix this we simply call trace_hardirqs_off_caller() and pass the
current instruction pointer.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
arch/s390/kernel/entry.S
arch/s390/kernel/entry64.S