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authorThomas Richter <tmricht@linux.ibm.com>2021-02-22 20:01:54 +0300
committerVasily Gorbik <gor@linux.ibm.com>2021-02-24 02:31:23 +0300
commitcf6acb8bdb1d829b85a4daa2944bf9e71c93f4b9 (patch)
tree13f99090c1be116bedfe848141ad27d2213e5c11 /arch/s390/include
parent182f709c5cff683e6732d04c78e328de0532284f (diff)
downloadlinux-cf6acb8bdb1d829b85a4daa2944bf9e71c93f4b9.tar.xz
s390/cpumf: Add support for complete counter set extraction
Add support to the CPU Measurement counter facility device driver to extract complete counter sets per CPU and per counter set from user space. This includes a new device named /dev/hwctr and support for the device driver functions open, close and ioctl. Other functions are not supported. The ioctl command supports 3 subcommands: S390_HWCTR_START: enables counter sets on a list of CPUs. S390_HWCTR_STOP: disables counter sets on a list of CPUs. S390_HWCTR_READ: reads counter sets on a list of CPUs. The ioctl(..., S390_HWCTR_READ, ...) is the only subcommand which returns data. It requires member data_bytes to be positive and indicates the maximum amount of data available to store counter set data. The other ioctl() subcommands do not use this member and it should be set to zero. The S390_HWCTR_READ subcommand returns the following data: The cpuset data is flattened using the following scheme, stored in member data: 0x0 0x8 0xc 0x10 0x10 0x18 0x20 0x28 0xU-1 +---------+-----+---------+-----+---------+-----+-----+------+------+ | no_cpus | cpu | no_sets | set | no_cnts | cv1 | cv2 | .... | cv_n | +---------+-----+---------+-----+---------+-----+-----+------+------+ 0xU 0xU+4 0xU+8 0xU+10 0xV-1 +-----+---------+-----+-----+------+------+ | set | no_cnts | cv1 | cv2 | .... | cv_n | +-----+---------+-----+-----+------+------+ 0xV 0xV+4 0xV+8 0xV+c +-----+---------+-----+---------+-----+-----+------+------+ | cpu | no_sets | set | no_cnts | cv1 | cv2 | .... | cv_n | +-----+---------+-----+---------+-----+-----+------+------+ U and V denote arbitrary hexadezimal addresses. The first integer represents the number of CPUs data was extracted from. This is followed by CPU number and number of counter sets extracted. Both are two integer values. This is followed by the set identifer and number of counters extracted. Both are two integer values. This is followed by the counter values, each element is eight bytes in size. The S390_HWCTR_READ ioctl subcommand is also limited to one call per minute. This ensures that an application does not read out the counter sets too often and reduces the overall CPU performance. The complete counter set extraction is an expensive operation. Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Signed-off-by: Thomas Richter <tmricht@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include')
-rw-r--r--arch/s390/include/uapi/asm/perf_cpum_cf_diag.h51
1 files changed, 51 insertions, 0 deletions
diff --git a/arch/s390/include/uapi/asm/perf_cpum_cf_diag.h b/arch/s390/include/uapi/asm/perf_cpum_cf_diag.h
new file mode 100644
index 000000000000..3d8284b95f87
--- /dev/null
+++ b/arch/s390/include/uapi/asm/perf_cpum_cf_diag.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright IBM Corp. 2021
+ * Interface implementation for communication with the CPU Measurement
+ * counter facility device driver.
+ *
+ * Author(s): Thomas Richter <tmricht@linux.ibm.com>
+ *
+ * Define for ioctl() commands to communicate with the CPU Measurement
+ * counter facility device driver.
+ */
+
+#ifndef _PERF_CPUM_CF_DIAG_H
+#define _PERF_CPUM_CF_DIAG_H
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+
+#define S390_HWCTR_DEVICE "hwctr"
+#define S390_HWCTR_START_VERSION 1
+
+struct s390_ctrset_start { /* Set CPUs to operate on */
+ __u64 version; /* Version of interface */
+ __u64 data_bytes; /* # of bytes required */
+ __u64 cpumask_len; /* Length of CPU mask in bytes */
+ __u64 *cpumask; /* Pointer to CPU mask */
+ __u64 counter_sets; /* Bit mask of counter sets to get */
+};
+
+struct s390_ctrset_setdata { /* Counter set data */
+ __u32 set; /* Counter set number */
+ __u32 no_cnts; /* # of counters stored in cv[] */
+ __u64 cv[0]; /* Counter values (variable length) */
+};
+
+struct s390_ctrset_cpudata { /* Counter set data per CPU */
+ __u32 cpu_nr; /* CPU number */
+ __u32 no_sets; /* # of counters sets in data[] */
+ struct s390_ctrset_setdata data[0];
+};
+
+struct s390_ctrset_read { /* Structure to get all ctr sets */
+ __u64 no_cpus; /* Total # of CPUs data taken from */
+ struct s390_ctrset_cpudata data[0];
+};
+
+#define S390_HWCTR_MAGIC 'C' /* Random magic # for ioctls */
+#define S390_HWCTR_START _IOWR(S390_HWCTR_MAGIC, 1, struct s390_ctrset_start)
+#define S390_HWCTR_STOP _IO(S390_HWCTR_MAGIC, 2)
+#define S390_HWCTR_READ _IOWR(S390_HWCTR_MAGIC, 3, struct s390_ctrset_read)
+#endif