perf list: Add s390 support for detailed/verbose pmu event description

From: Thomas Richter <[email protected]>

Perf list with flags -d and -v print a description (-d) or a very verbose explanation (-v) of CPU specific counter events. These descriptions are provided with the json files in directory pmu-events/arch/s390/*.json.

Display of these descriptions on s390 requires the corresponding json files.

On s390 this does not work because function is_pmu_core() does not detect the s390 directory name where the CPU specific events are listed. On x86 it is
/sys/bus/event_source/devices/cpu
whereas on s390 it is
/sys/bus/event_source/devices/cpum_cf /sys/bus/event_source/devices/cpum_sf

Fix this by adding s390 directory name testing to function is_pmu_core(). This is the same approach as taken for arm platform.

Output before:
[root@s35lp76 perf]# ./perf list -d pmu
List of pre-defined events (to be used in -e):

  cpum_cf/AES_BLOCKED_CYCLES/      [Kernel PMU event]
  cpum_cf/AES_BLOCKED_FUNCTIONS/   [Kernel PMU event]
  cpum_cf/AES_CYCLES/              [Kernel PMU event]
  cpum_cf/AES_FUNCTIONS/           [Kernel PMU event]
  ....
  cpum_cf/TX_NC_TEND/              [Kernel PMU event]
  cpum_cf/VX_BCD_EXECUTION_SLOTS/  [Kernel PMU event]
  cpum_sf/SF_CYCLES_BASIC/         [Kernel PMU event]

Output after:
[root@s35lp76 perf]# ./perf list -d pmu
List of pre-defined events (to be used in -e):

  cpum_cf/AES_BLOCKED_CYCLES/      [Kernel PMU event]
  cpum_cf/AES_BLOCKED_FUNCTIONS/   [Kernel PMU event]
  cpum_cf/AES_CYCLES/              [Kernel PMU event]
  cpum_cf/AES_FUNCTIONS/           [Kernel PMU event]
  ....
  cpum_cf/TX_NC_TEND/              [Kernel PMU event]
  cpum_cf/VX_BCD_EXECUTION_SLOTS/  [Kernel PMU event]
  cpum_sf/SF_CYCLES_BASIC/         [Kernel PMU event]

3906:
bcd_dfp_execution_slots
[BCD DFP Execution Slots]
decimal_instructions
[Decimal Instructions]
dtlb2_gpage_writes
[DTLB2 GPAGE Writes]
dtlb2_hpage_writes
[DTLB2 HPAGE Writes]
dtlb2_misses
[DTLB2 Misses]
dtlb2_writes
[DTLB2 Writes]
itlb2_misses
[ITLB2 Misses]
itlb2_writes
[ITLB2 Writes]
l1c_tlb2_misses
[L1C TLB2 Misses]
.....

cfvn 3:
cpu_cycles
[CPU Cycles]
instructions
[Instructions]
l1d_dir_writes
[L1D Directory Writes]
l1d_penalty_cycles
[L1D Penalty Cycles]
l1i_dir_writes
[L1I Directory Writes]
l1i_penalty_cycles
[L1I Penalty Cycles]
problem_state_cpu_cycles
[Problem State CPU Cycles]
problem_state_instructions
[Problem State Instructions]
....

csvn generic:
aes_blocked_cycles
[AES Blocked Cycles]
aes_blocked_functions
[AES Blocked Functions]
aes_cycles
[AES Cycles]
aes_functions
[AES Functions]
dea_blocked_cycles
[DEA Blocked Cycles]
dea_blocked_functions
[DEA Blocked Functions]
....

---
 tools/perf/util/pmu.c | 6 ++++++
 1 file changed, 6 insertions(+)

index 1111d5bf15ca..8675ddf558c6 100644
@@ -562,6 +562,12 @@ static int is_pmu_core(const char *name)
 	if (stat(path, &st) == 0)
 		return 1;
 
+	/* Look for cpu sysfs (specific to s390) */
+	scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s",
+		  sysfs, name);
+	if (stat(path, &st) == 0 && !strncmp(name, "cpum_", 5))
+		return 1;
+
 	return 0;
 }
 

2.14.3