GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/trusted-firmware/trusted-firmware-a-2.8/docs/perf/performance-monitoring-unit.rst

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+Performance Monitoring Unit
+===========================
+
+The Performance Monitoring Unit (PMU) allows recording of architectural and
+microarchitectural events for profiling purposes.
+
+This document gives an overview of the PMU counter configuration to assist with
+implementation and to complement the PMU security guidelines given in the
+:ref:`Secure Development Guidelines` document.
+
+.. note::
+   This section applies to Armv8-A implementations which have version 3
+   of the Performance Monitors Extension (PMUv3).
+
+PMU Counters
+------------
+
+The PMU makes 32 counters available at all privilege levels:
+
+-  31 programmable event counters: ``PMEVCNTR<n>``, where ``n`` is ``0`` to
+   ``30``.
+-  A dedicated cycle counter: ``PMCCNTR``.
+
+Architectural mappings
+~~~~~~~~~~~~~~~~~~~~~~
+
++--------------+---------+----------------------------+
+| Counters     | State   | System Register Name       |
++==============+=========+============================+
+|              | AArch64 | ``PMEVCNTR<n>_EL0[63*:0]`` |
+| Programmable +---------+----------------------------+
+|              | AArch32 | ``PMEVCNTR<n>[31:0]``      |
++--------------+---------+----------------------------+
+|              | AArch64 | ``PMCCNTR_EL0[63:0]``      |
+| Cycle        +---------+----------------------------+
+|              | AArch32 | ``PMCCNTR[63:0]``          |
++--------------+---------+----------------------------+
+
+.. note::
+   Bits [63:32] are only available if ARMv8.5-PMU is implemented. Refer to the
+   `Arm ARM`_ for a detailed description of ARMv8.5-PMU features.
+
+Configuring the PMU for counting events
+---------------------------------------
+
+Each programmable counter has an associated register, ``PMEVTYPER<n>`` which
+configures it. The cycle counter has the ``PMCCFILTR_EL0`` register, which has
+an identical function and bit field layout as ``PMEVTYPER<n>``. In addition,
+the counters are enabled (permitted to increment) via the ``PMCNTENSET`` and
+``PMCR`` registers. These can be accessed at all privilege levels.
+
+Architectural mappings
+~~~~~~~~~~~~~~~~~~~~~~
+
++-----------------------------+------------------------+
+| AArch64                     | AArch32                |
++=============================+========================+
+| ``PMEVTYPER<n>_EL0[63*:0]`` | ``PMEVTYPER<n>[31:0]`` |
++-----------------------------+------------------------+
+| ``PMCCFILTR_EL0[63*:0]``    | ``PMCCFILTR[31:0]``    |
++-----------------------------+------------------------+
+| ``PMCNTENSET_EL0[63*:0]``   | ``PMCNTENSET[31:0]``   |
++-----------------------------+------------------------+
+| ``PMCR_EL0[63*:0]``         | ``PMCR[31:0]``         |
++-----------------------------+------------------------+
+
+.. note::
+   Bits [63:32] are reserved.
+
+Relevant register fields
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+For ``PMEVTYPER<n>_EL0``/``PMEVTYPER<n>`` and ``PMCCFILTR_EL0/PMCCFILTR``, the
+most important fields are:
+
+-  ``P``:
+
+   -  Bit 31.
+   -  If set to ``0``, will increment the associated ``PMEVCNTR<n>`` at EL1.
+
+-  ``NSK``:
+
+   -  Bit 29.
+   -  If equal to the ``P`` bit it enables the associated ``PMEVCNTR<n>`` at
+      Non-secure EL1.
+   -  Reserved if EL3 not implemented.
+
+-  ``NSH``:
+
+   -  Bit 27.
+   -  If set to ``1``, will increment the associated ``PMEVCNTR<n>`` at EL2.
+   -  Reserved if EL2 not implemented.
+
+-  ``SH``:
+
+   -  Bit 24.
+   -  If different to the ``NSH`` bit it enables the associated ``PMEVCNTR<n>``
+      at Secure EL2.
+   -  Reserved if Secure EL2 not implemented.
+
+-  ``M``:
+
+   -  Bit 26.
+   -  If equal to the ``P`` bit it enables the associated ``PMEVCNTR<n>`` at
+      EL3.
+
+-  ``evtCount[15:10]``:
+
+   -  Extension to ``evtCount[9:0]``. Reserved unless ARMv8.1-PMU implemented.
+
+-  ``evtCount[9:0]``:
+
+   -  The event number that the associated ``PMEVCNTR<n>`` will count.
+
+For ``PMCNTENSET_EL0``/``PMCNTENSET``, the most important fields are:
+
+-  ``P[30:0]``:
+
+   -  Setting bit ``P[n]`` to ``1`` enables counter ``PMEVCNTR<n>``.
+   -  The effects of ``PMEVTYPER<n>`` are applied on top of this.
+      In other words, the counter will not increment at any privilege level or
+      security state unless it is enabled here.
+
+-  ``C``:
+
+   -  Bit 31.
+   -  If set to ``1`` enables the cycle counter ``PMCCNTR``.
+
+For ``PMCR``/``PMCR_EL0``, the most important fields are:
+
+-  ``DP``:
+
+   -  Bit 5.
+   -  If set to ``1`` it disables the cycle counter ``PMCCNTR`` where event
+      counting (by ``PMEVCNTR<n>``) is prohibited (e.g. EL2 and the Secure
+      world).
+   -  If set to ``0``, ``PMCCNTR`` will not be affected by this bit and
+      therefore will be able to count where the programmable counters are
+      prohibited.
+
+-  ``E``:
+
+   -  Bit 0.
+   -  Enables/disables counting altogether.
+   -  The effects of ``PMCNTENSET`` and ``PMCR.DP`` are applied on top of this.
+      In other words, if this bit is ``0`` then no counters will increment
+      regardless of how the other PMU system registers or bit fields are
+      configured.
+
+.. rubric:: References
+
+-  `Arm ARM`_
+
+--------------
+
+*Copyright (c) 2019-2020, Arm Limited and Contributors. All rights reserved.*
+
+.. _Arm ARM: https://developer.arm.com/docs/ddi0487/latest