lib/extensions/spe/spe.c

   1 /*
   2  * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
   3  *
   4  * SPDX-License-Identifier: BSD-3-Clause
   5  */
   6
   7 #include <arch.h>
   8 #include <arch_helpers.h>
   9 #include <pubsub.h>
  10 #include <spe.h>
  11 #include <stdbool.h>
  12
  13 static inline void psb_csync(void)
  14 {
  15         /*
  16          * The assembler does not yet understand the psb csync mnemonic
  17          * so use the equivalent hint instruction.
  18          */
  19         __asm__ volatile("hint #17");
  20 }
  21
  22 bool spe_supported(void)
  23 {
  24         uint64_t features;
  25
  26         features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_PMS_SHIFT;
  27         return (features & ID_AA64DFR0_PMS_MASK) == 1U;
  28 }
  29
  30 void spe_enable(bool el2_unused)
  31 {
  32         uint64_t v;
  33
  34         if (!spe_supported())
  35                 return;
  36
  37         if (el2_unused) {
  38                 /*
  39                  * MDCR_EL2.TPMS (ARM v8.2): Do not trap statistical
  40                  * profiling controls to EL2.
  41                  *
  42                  * MDCR_EL2.E2PB (ARM v8.2): SPE enabled in Non-secure
  43                  * state. Accesses to profiling buffer controls at
  44                  * Non-secure EL1 are not trapped to EL2.
  45                  */
  46                 v = read_mdcr_el2();
  47                 v &= ~MDCR_EL2_TPMS;
  48                 v |= MDCR_EL2_E2PB(MDCR_EL2_E2PB_EL1);
  49                 write_mdcr_el2(v);
  50         }
  51
  52         /*
  53          * MDCR_EL2.NSPB (ARM v8.2): SPE enabled in Non-secure state
  54          * and disabled in secure state. Accesses to SPE registers at
  55          * S-EL1 generate trap exceptions to EL3.
  56          */
  57         v = read_mdcr_el3();
  58         v |= MDCR_NSPB(MDCR_NSPB_EL1);
  59         write_mdcr_el3(v);
  60 }
  61
  62 void spe_disable(void)
  63 {
  64         uint64_t v;
  65
  66         if (!spe_supported())
  67                 return;
  68
  69         /* Drain buffered data */
  70         psb_csync();
  71         dsbnsh();
  72
  73         /* Disable profiling buffer */
  74         v = read_pmblimitr_el1();
  75         v &= ~(1ULL << 0);
  76         write_pmblimitr_el1(v);
  77         isb();
  78 }
  79
  80 static void *spe_drain_buffers_hook(const void *arg)
  81 {
  82         if (!spe_supported())
  83                 return (void *)-1;
  84
  85         /* Drain buffered data */
  86         psb_csync();
  87         dsbnsh();
  88
  89         return (void *)0;
  90 }
  91
  92 SUBSCRIBE_TO_EVENT(cm_entering_secure_world, spe_drain_buffers_hook);