[Qemu-arm] [PATCH v3 18/22] target/arm: Add array for supported PMU events, generate PMCEID[01]

[Aaron Lindsay <alindsay@codeaurora.org>]

This commit doesn't add any supported events, but provides the framework
for adding them. We store the pm_event structs in a simple array, and
provide the mapping from the event numbers to array indexes in
the supported_event_map array.

Signed-off-by: Aaron Lindsay <alindsay@codeaurora.org>
---
 target/arm/cpu.c    |  4 ++++
 target/arm/cpu.h    | 10 ++++++++++
 target/arm/helper.c | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index e544f1d..69d6a80 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -889,6 +889,10 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
         unset_feature(env, ARM_FEATURE_PMU);
         cpu->id_aa64dfr0 &= ~0xf00;
     } else {
+        uint64_t pmceid = get_pmceid(&cpu->env);
+        cpu->pmceid0 = pmceid & 0xffffffff;
+        cpu->pmceid1 = (pmceid >> 32) & 0xffffffff;
+
         arm_register_pre_el_change_hook(cpu, &pmu_pre_el_change, 0);
         arm_register_el_change_hook(cpu, &pmu_post_el_change, 0);
     }
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index cc1e2fb..19f005d 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -931,6 +931,16 @@ void pmu_op_finish(CPUARMState *env, uint64_t prev_cycles);
 void pmu_pre_el_change(ARMCPU *cpu, void *ignored);
 void pmu_post_el_change(ARMCPU *cpu, void *ignored);
 
+/*
+ * get_pmceid
+ * @env: CPUARMState
+ *
+ * Return the PMCEID[01] register values corresponding to the counters which
+ * are supported given the current configuration (0 is low 32, 1 is high 32
+ * bits)
+ */
+uint64_t get_pmceid(CPUARMState *env);
+
 /* SCTLR bit meanings. Several bits have been reused in newer
  * versions of the architecture; in that case we define constants
  * for both old and new bit meanings. Code which tests against those
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 2073d56..6a4f900 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -925,6 +925,43 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
 /* Bits allowed to be set/cleared for PMCNTEN* and PMINTEN* */
 #define PMU_COUNTER_MASK(env) ((1 << 31) | ((1 << PMU_NUM_COUNTERS(env)) - 1))
 
+typedef struct pm_event {
+    uint16_t number; /* PMEVTYPER.evtCount is 10 bits wide */
+    /* If the event is supported on this CPU (used to generate PMCEID[01]) */
+    bool (*supported)(CPUARMState *);
+    /* Retrieve the current count of the underlying event. The programmed
+     * counters hold a difference from the return value from this function */
+    uint64_t (*get_count)(CPUARMState *);
+} pm_event;
+
+#define SUPPORTED_EVENT_SENTINEL UINT16_MAX
+static const pm_event pm_events[] = {
+    { .number = SUPPORTED_EVENT_SENTINEL }
+};
+static uint16_t supported_event_map[0x3f];
+
+/*
+ * Called upon initialization to build PMCEID0 (low 32 bits) and PMCEID1 (high
+ * 32). We also use it to build a map of ARM event numbers to indices in
+ * our pm_events array.
+ */
+uint64_t get_pmceid(CPUARMState *env)
+{
+    uint64_t pmceid = 0;
+    unsigned int i = 0;
+    while (pm_events[i].number != SUPPORTED_EVENT_SENTINEL) {
+        const pm_event *cnt = &pm_events[i];
+        if (cnt->number < 0x3f && cnt->supported(env)) {
+            pmceid |= (1 << cnt->number);
+            supported_event_map[cnt->number] = i;
+        } else {
+            supported_event_map[cnt->number] = SUPPORTED_EVENT_SENTINEL;
+        }
+        i++;
+    }
+    return pmceid;
+}
+
 static CPAccessResult pmreg_access(CPUARMState *env, const ARMCPRegInfo *ri,
                                    bool isread)
 {
-- 
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