tree e6e6167a6045feaccc290a6fdd599bea2854ef19
parent 6c662c519277d9d94f4d146b7c05e67a426b91a7
author Philipp Rudo <prudo@linux.ibm.com> 1586177268 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1589099409 +0200

s390/ftrace: fix potential crashes when switching tracers

[ Upstream commit 8ebf6da9db1b2a20bb86cc1bee2552e894d03308 ]

Switching tracers include instruction patching. To prevent that a
instruction is patched while it's read the instruction patching is done
in stop_machine 'context'. This also means that any function called
during stop_machine must not be traced. Thus add 'notrace' to all
functions called within stop_machine.

Fixes: 1ec2772e0c3c ("s390/diag: add a statistic for diagnose calls")
Fixes: 38f2c691a4b3 ("s390: improve wait logic of stop_machine")
Fixes: 4ecf0a43e729 ("processor: get rid of cpu_relax_yield")
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>