s390/cpumf: Allow concurrent access for CPU Measurement Counter Facility

Commit cf6acb8bdb1d ("s390/cpumf: Add support for complete counter set extraction")
allows access to the CPU Measurement Counter Facility via character
device /dev/hwctr. The access was exclusive via this device or
via perf_event_open() system call. Only one path at a time was
permitted. The CPU Measurement Counter Facility device driver blocked
access to other processes.

This patch removes this restriction and allows concurrent access to
the CPU Measurement Counter Facility from multiple processes at the same
time via perf_event_open() SVC and via /dev/hwctr device. The access
via /dev/hwctr device is still exclusive, only one process is allowed to
access this device.

This patch
- moves the /dev/hwctr device access from file perf_cpum_cf_diag.c.
  to file perf_cpum_cf.c.
- use only one trace buffer .../s390dbf/cpum_cf.
- remove cfset_csd structure and includes its members it into the
  structure cpu_cf_events. This results in one data structure and
  simplifies the access.
- rework function familiy ctr_set_enable, ctr_set_disable, ctr_set_start
  and ctr_set_stop which operate on a counter set number.
  Now they operate on a counter set bit mask.
- move CF_DIAG event functionality to file perf_cpum_cf.c. It now
  contains the complete functionality of the CPU Measurement Counter
  Facility:
  - Performance measurement support for counters using perf stat.
  - Support for complete counter set extraction with device /dev/hwctr.
  - Support for counter set extraction event CF_DIAG attached to
    samples using perf record.
- removes file perf_cpum_cf_diag.c

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 7 insertions, 20 deletions

diff --git a/arch/s390/kernel/perf_cpum_cf_common.c b/arch/s390/kernel/perf_cpum_cf_common.c
index 2300fbaac556..30f0242de4a5 100644
--- a/arch/s390/kernel/perf_cpum_cf_common.c
+++ b/arch/s390/kernel/perf_cpum_cf_common.c
@@ -29,7 +29,11 @@ DEFINE_PER_CPU(struct cpu_cf_events, cpu_cf_events) = {
 	},
 	.alert = ATOMIC64_INIT(0),
 	.state = 0,
+	.dev_state = 0,
 	.flags = 0,
+	.used = 0,
+	.usedss = 0,
+	.sets = 0
 };
 /* Indicator whether the CPU-Measurement Counter Facility Support is ready */
 static bool cpum_cf_initalized;
@@ -96,25 +100,10 @@ bool kernel_cpumcf_avail(void)
 }
 EXPORT_SYMBOL(kernel_cpumcf_avail);
 
-
-/* Reserve/release functions for sharing perf hardware */
-static DEFINE_SPINLOCK(cpumcf_owner_lock);
-static void *cpumcf_owner;
-
 /* Initialize the CPU-measurement counter facility */
 int __kernel_cpumcf_begin(void)
 {
 	int flags = PMC_INIT;
-	int err = 0;
-
-	spin_lock(&cpumcf_owner_lock);
-	if (cpumcf_owner)
-		err = -EBUSY;
-	else
-		cpumcf_owner = __builtin_return_address(0);
-	spin_unlock(&cpumcf_owner_lock);
-	if (err)
-		return err;
 
 	on_each_cpu(cpum_cf_setup_cpu, &flags, 1);
 	irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
@@ -144,10 +133,6 @@ void __kernel_cpumcf_end(void)
 
 	on_each_cpu(cpum_cf_setup_cpu, &flags, 1);
 	irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
-
-	spin_lock(&cpumcf_owner_lock);
-	cpumcf_owner = NULL;
-	spin_unlock(&cpumcf_owner_lock);
 }
 EXPORT_SYMBOL(__kernel_cpumcf_end);
 
@@ -161,11 +146,13 @@ static int cpum_cf_setup(unsigned int cpu, int flags)
 
 static int cpum_cf_online_cpu(unsigned int cpu)
 {
-	return cpum_cf_setup(cpu, PMC_INIT);
+	cpum_cf_setup(cpu, PMC_INIT);
+	return cfset_online_cpu(cpu);
 }
 
 static int cpum_cf_offline_cpu(unsigned int cpu)
 {
+	cfset_offline_cpu(cpu);
 	return cpum_cf_setup(cpu, PMC_RELEASE);
 }