linux-stable/arch/s390/kernel/trace.c
Philipp Rudo 8ebf6da9db s390/ftrace: fix potential crashes when switching tracers
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>
2020-04-22 16:20:55 +02:00

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C

// SPDX-License-Identifier: GPL-2.0
/*
* Tracepoint definitions for s390
*
* Copyright IBM Corp. 2015
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/percpu.h>
#define CREATE_TRACE_POINTS
#include <asm/trace/diag.h>
EXPORT_TRACEPOINT_SYMBOL(s390_diagnose);
static DEFINE_PER_CPU(unsigned int, diagnose_trace_depth);
void notrace trace_s390_diagnose_norecursion(int diag_nr)
{
unsigned long flags;
unsigned int *depth;
/* Avoid lockdep recursion. */
if (IS_ENABLED(CONFIG_LOCKDEP))
return;
local_irq_save(flags);
depth = this_cpu_ptr(&diagnose_trace_depth);
if (*depth == 0) {
(*depth)++;
trace_s390_diagnose(diag_nr);
(*depth)--;
}
local_irq_restore(flags);
}