[S390] perf: add support for s390x CPU counters

Add a perf PMU to access the CPU-measurement counter facility CPUM CF.
CPUM CF provides multiple counter sets for measuring generic,
problem-state, and crypto activaties.  Also an extended counter set for
the IBM System z10 and IBM z196 mainframes is available.

Counters from the basic and problem-state counter set are mapped to
generic perf hardware events.  Other counters are accessible through
raw events.

For a list of available counter sets and counters, see:

  - The Load-Program-Parameter and the CPU-Measurement Facilities (SA23-2260)
  - The CPU-Measurement Facility Extended Counters Definition for
    z10 and z196 (SA23-2261)

Reviewed-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 125 insertions, 0 deletions

diff --git a/arch/s390/kernel/perf_event.c b/arch/s390/kernel/perf_event.c
new file mode 100644
index 000000000000..609f985198cf
--- /dev/null
+++ b/arch/s390/kernel/perf_event.c
@@ -0,0 +1,125 @@
+/*
+ * Performance event support for s390x
+ *
+ *  Copyright IBM Corp. 2012
+ *  Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ */
+#define KMSG_COMPONENT  "perf"
+#define pr_fmt(fmt)     KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <linux/percpu.h>
+#include <linux/export.h>
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <asm/cpu_mf.h>
+#include <asm/lowcore.h>
+#include <asm/processor.h>
+
+const char *perf_pmu_name(void)
+{
+        if (cpum_cf_avail() || cpum_sf_avail())
+                return "CPU-measurement facilities (CPUMF)";
+        return "pmu";
+}
+EXPORT_SYMBOL(perf_pmu_name);
+
+int perf_num_counters(void)
+{
+        int num = 0;
+
+        if (cpum_cf_avail())
+                num += PERF_CPUM_CF_MAX_CTR;
+
+        return num;
+}
+EXPORT_SYMBOL(perf_num_counters);
+
+void perf_event_print_debug(void)
+{
+        struct cpumf_ctr_info cf_info;
+        unsigned long flags;
+        int cpu;
+
+        if (!cpum_cf_avail())
+                return;
+
+        local_irq_save(flags);
+
+        cpu = smp_processor_id();
+        memset(&cf_info, 0, sizeof(cf_info));
+        if (!qctri(&cf_info)) {
+                pr_info("CPU[%i] CPUM_CF: ver=%u.%u A=%04x E=%04x C=%04x\n",
+                        cpu, cf_info.cfvn, cf_info.csvn,
+                        cf_info.auth_ctl, cf_info.enable_ctl, cf_info.act_ctl);
+                print_hex_dump_bytes("CPUMF Query: ", DUMP_PREFIX_OFFSET,
+                                     &cf_info, sizeof(cf_info));
+        }
+
+        local_irq_restore(flags);
+}
+
+/* See also arch/s390/kernel/traps.c */
+static unsigned long __store_trace(struct perf_callchain_entry *entry,
+                                   unsigned long sp,
+                                   unsigned long low, unsigned long high)
+{
+        struct stack_frame *sf;
+        struct pt_regs *regs;
+
+        while (1) {
+                sp = sp & PSW_ADDR_INSN;
+                if (sp < low || sp > high - sizeof(*sf))
+                        return sp;
+                sf = (struct stack_frame *) sp;
+                perf_callchain_store(entry, sf->gprs[8] & PSW_ADDR_INSN);
+                /* Follow the backchain. */
+                while (1) {
+                        low = sp;
+                        sp = sf->back_chain & PSW_ADDR_INSN;
+                        if (!sp)
+                                break;
+                        if (sp <= low || sp > high - sizeof(*sf))
+                                return sp;
+                        sf = (struct stack_frame *) sp;
+                        perf_callchain_store(entry,
+                                             sf->gprs[8] & PSW_ADDR_INSN);
+                }
+                /* Zero backchain detected, check for interrupt frame. */
+                sp = (unsigned long) (sf + 1);
+                if (sp <= low || sp > high - sizeof(*regs))
+                        return sp;
+                regs = (struct pt_regs *) sp;
+                perf_callchain_store(entry, sf->gprs[8] & PSW_ADDR_INSN);
+                low = sp;
+                sp = regs->gprs[15];
+        }
+}
+
+void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                           struct pt_regs *regs)
+{
+        unsigned long head;
+        struct stack_frame *head_sf;
+
+        if (user_mode(regs))
+                return;
+
+        head = regs->gprs[15];
+        head_sf = (struct stack_frame *) head;
+
+        if (!head_sf || !head_sf->back_chain)
+                return;
+
+        head = head_sf->back_chain;
+        head = __store_trace(entry, head, S390_lowcore.async_stack - ASYNC_SIZE,
+                             S390_lowcore.async_stack);
+
+        __store_trace(entry, head, S390_lowcore.thread_info,
+                      S390_lowcore.thread_info + THREAD_SIZE);
+}