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Commit bbe15f16 authored by Philipp Rudo's avatar Philipp Rudo Committed by Greg Kroah-Hartman
Browse files

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: 1ec2772e ("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: default avatarPhilipp Rudo <prudo@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 6c662c51

arch/s390/kernel/diag.c

+1 −1
Original line number Diff line number Diff line
@@ -128,7 +128,7 @@ 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);

arch/s390/kernel/smp.c

+2 −2
Original line number Diff line number Diff line
@@ -393,7 +393,7 @@ 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;
@@ -403,7 +403,7 @@ 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);

arch/s390/kernel/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -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;