@@ -1032,6 +1032,17 @@ static inline bool cp_access_ok(int current_pl,
}
/**
+ * pmccntr_sync
+ * @cpu: ARMCPU
+ *
+ * Syncronises the counter in the PMCCNTR. This must always be called twice,
+ * once before any action that might effect the timer and again afterwards.
+ * The function is used to swap the state of the register if required.
+ * This only happens when not in user mode (!CONFIG_USER_ONLY)
+ */
+void pmccntr_sync(CPUARMState *env);
+
+/**
* write_list_to_cpustate
* @cpu: ARMCPU
*
@@ -586,6 +586,25 @@ static bool arm_ccnt_enabled(CPUARMState *env)
}
#endif
+void pmccntr_sync(CPUARMState *env)
+{
+#ifndef CONFIG_USER_ONLY
+ uint64_t temp_ticks;
+
+ temp_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL),
+ get_ticks_per_sec(), 1000000);
+
+ if (env->cp15.c9_pmcr & PMCRD) {
+ /* Increment once every 64 processor clock cycles */
+ temp_ticks /= 64;
+ }
+
+ if (arm_ccnt_enabled(env)) {
+ env->cp15.c15_ccnt = temp_ticks - env->cp15.c15_ccnt;
+ }
+#endif
+}
+
#ifndef CONFIG_USER_ONLY
static void pmcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
uint64_t value)
This is used to synchronise the PMCCNTR counter and swap its state between enabled and disabled if required. It must always be called twice, both before and after any logic that could change the state of the PMCCNTR counter. Signed-off-by: Alistair Francis <alistair.francis@xilinx.com> --- Remembering that the c15_ccnt register stores the last time the counter was reset if enabled. If disabled it stores the counter value (when it was disabled). The three use cases are as below: -- Starts enabled/disabled and is staying enabled/disabled -- The two calls to pmccntr_sync cancel each other out. Each call implements this logic: env->cp15.c15_ccnt = temp_ticks - env->cp15.c15_ccnt Which expands to: env->cp15.c15_ccnt = temp_ticks - (temp_ticks - env->cp15.c15_ccnt) env->cp15.c15_ccnt = env->cp15.c15_ccnt -- Starts enabled, gets disabled -- The logic is run during the first call while during the second call it is not. That means that c15_ccnt changes from storing the last time the counter was reset, to storing the absolute value of the counter. -- Starts disabled, gets enabled -- During the fist call no changes are made, while during the second call the register is changed. This changes it from storing the absolute value to storing the last time the counter was reset. target-arm/cpu.h | 11 +++++++++++ target-arm/helper.c | 19 +++++++++++++++++++ 2 files changed, 30 insertions(+), 0 deletions(-)