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s390/ftrace: fix potential crashes when switching tracers 

commit 8ebf6da9db upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Philipp Rudo 2020-04-06 14:47:48 +02:00 committed by Greg Kroah-Hartman
parent 1f107e441b
commit 37405f2963
3 changed files with 4 additions and 4 deletions
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2
arch/s390/kernel/diag.c
View File

@ -133,7 +133,7 @@ void diag_stat_inc(enum diag_stat_enum nr)
}
EXPORT_SYMBOL(diag_stat_inc);
void diag_stat_inc_norecursion(enum diag_stat_enum nr)
void notrace diag_stat_inc_norecursion(enum diag_stat_enum nr)
{
this_cpu_inc(diag_stat.counter[nr]);
trace_s390_diagnose_norecursion(diag_map[nr].code);

4
arch/s390/kernel/smp.c
View File

@ -403,7 +403,7 @@ int smp_find_processor_id(u16 address)
return -1;
}
bool arch_vcpu_is_preempted(int cpu)
bool notrace arch_vcpu_is_preempted(int cpu)
{
if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
return false;
@ -413,7 +413,7 @@ bool arch_vcpu_is_preempted(int cpu)
}
EXPORT_SYMBOL(arch_vcpu_is_preempted);
void smp_yield_cpu(int cpu)
void notrace smp_yield_cpu(int cpu)
{
if (MACHINE_HAS_DIAG9C) {
diag_stat_inc_norecursion(DIAG_STAT_X09C);

2
arch/s390/kernel/trace.c
View File

@ -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;