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s390/ftrace: fix potential crashes when switching tracers

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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: 1ec2772e0c ("s390/diag: add a statistic for diagnose calls")
Fixes: 38f2c691a4 ("s390: improve wait logic of stop_machine")
Fixes: 4ecf0a43e7 ("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>
This commit is contained in:
Philipp Rudo
2020-04-06 14:47:48 +02:00
committed by Vasily Gorbik
parent ae83d0b416
commit 8ebf6da9db
3 changed files with 4 additions and 4 deletions
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arch/s390/kernel/trace.c
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@@ -14,7 +14,7 @@ EXPORT_TRACEPOINT_SYMBOL(s390_diagnose);
static DEFINE_PER_CPU(unsigned int, diagnose_trace_depth);
void trace_s390_diagnose_norecursion(int diag_nr)
void notrace trace_s390_diagnose_norecursion(int diag_nr)
{
unsigned long flags;
unsigned int *depth;