riscv/execute.cc

   1 // See LICENSE for license details.
   2
   3 #include "processor.h"
   4 #include "mmu.h"
   5 #include "sim.h"
   6 #include <cassert>
   7
   8
   9 static void commit_log_stash_privilege(state_t* state)
  10 {
  11 #ifdef RISCV_ENABLE_COMMITLOG
  12   state->last_inst_priv = state->prv;
  13 #endif
  14 }
  15
  16 static void commit_log_print_insn(state_t* state, reg_t pc, insn_t insn)
  17 {
  18 #ifdef RISCV_ENABLE_COMMITLOG
  19   int32_t priv = state->last_inst_priv;
  20   uint64_t mask = (insn.length() == 8 ? uint64_t(0) : (uint64_t(1) << (insn.length() * 8))) - 1;
  21   if (state->log_reg_write.addr) {
  22     fprintf(stderr, "%1d 0x%016" PRIx64 " (0x%08" PRIx64 ") %c%2" PRIu64 " 0x%016" PRIx64 "\n",
  23             priv,
  24             pc,
  25             insn.bits() & mask,
  26             state->log_reg_write.addr & 1 ? 'f' : 'x',
  27             state->log_reg_write.addr >> 1,
  28             state->log_reg_write.data);
  29   } else {
  30     fprintf(stderr, "%1d 0x%016" PRIx64 " (0x%08" PRIx64 ")\n", priv, pc, insn.bits() & mask);
  31   }
  32   state->log_reg_write.addr = 0;
  33 #endif
  34 }
  35
  36 inline void processor_t::update_histogram(reg_t pc)
  37 {
  38 #ifdef RISCV_ENABLE_HISTOGRAM
  39   pc_histogram[pc]++;
  40 #endif
  41 }
  42
  43 static reg_t execute_insn(processor_t* p, reg_t pc, insn_fetch_t fetch)
  44 {
  45   commit_log_stash_privilege(p->get_state());
  46   reg_t npc = fetch.func(p, fetch.insn, pc);
  47   if (!invalid_pc(npc)) {
  48     commit_log_print_insn(p->get_state(), pc, fetch.insn);
  49     p->update_histogram(pc);
  50   }
  51   return npc;
  52 }
  53
  54 // fetch/decode/execute loop
  55 void processor_t::step(size_t n)
  56 {
  57   // TODO: get_interrupt() isn't super fast. Does that matter?
  58   if (state.dcsr.cause == DCSR_CAUSE_NONE &&
  59       sim->debug_module.get_interrupt(id)) {
  60     enter_debug_mode(DCSR_CAUSE_DEBUGINT);
  61   }
  62
  63   if (state.dcsr.cause != DCSR_CAUSE_NONE) {
  64     // In Debug Mode, just do 11 steps at a time. Otherwise we're going to be
  65     // spinning the rest of the time anyway.
  66     n = std::min(n, (size_t) 11);
  67   }
  68
  69   if (debug) {
  70     fprintf(stderr, "step(%ld)\n", n);
  71   }
  72
  73   while (n > 0) {
  74     size_t instret = 0;
  75     reg_t pc = state.pc;
  76     mmu_t* _mmu = mmu;
  77
  78     #define advance_pc() \
  79      if (unlikely(invalid_pc(pc))) { \
  80        switch (pc) { \
  81          case PC_SERIALIZE_BEFORE: state.serialized = true; break; \
  82          case PC_SERIALIZE_AFTER: instret++; break; \
  83          default: abort(); \
  84        } \
  85        pc = state.pc; \
  86        break; \
  87      } else { \
  88        state.pc = pc; \
  89        instret++; \
  90      }
  91
  92     try
  93     {
  94       take_interrupt();
  95
  96       // When we might single step, use the slow loop instead of the fast one.
  97       if (unlikely(debug || state.single_step != state.STEP_NONE || state.dcsr.cause))
  98       {
  99         while (instret < n)
 100         {
 101           // TODO: implement this for the main loop also.  To keep
 102           // performance good, probably go into this version when entering
 103           // debug mode or something.
 104           if (unlikely(state.single_step == state.STEP_STEPPING)) {
 105             state.single_step = state.STEP_STEPPED;
 106           } else if (unlikely(state.single_step == state.STEP_STEPPED)) {
 107             state.single_step = state.STEP_NONE;
 108             enter_debug_mode(DCSR_CAUSE_STEP);
 109             // enter_debug_mode changed state.pc, so we can't just continue.
 110             break;
 111           }
 112
 113           insn_fetch_t fetch = mmu->load_insn(pc);
 114           if (debug && !state.serialized)
 115             disasm(fetch.insn);
 116           pc = execute_insn(this, pc, fetch);
 117           advance_pc();
 118         }
 119       }
 120       else while (instret < n)
 121       {
 122         size_t idx = _mmu->icache_index(pc);
 123         auto ic_entry = _mmu->access_icache(pc);
 124
 125         #define ICACHE_ACCESS(i) { \
 126           insn_fetch_t fetch = ic_entry->data; \
 127           ic_entry++; \
 128           pc = execute_insn(this, pc, fetch); \
 129           if (i == mmu_t::ICACHE_ENTRIES-1) break; \
 130           if (unlikely(ic_entry->tag != pc)) goto miss; \
 131           if (unlikely(instret+1 == n)) break; \
 132           instret++; \
 133           state.pc = pc; \
 134         }
 135
 136         switch (idx) {
 137           #include "icache.h"
 138         }
 139
 140         advance_pc();
 141         continue;
 142
 143 miss:
 144         advance_pc();
 145         // refill I$ if it looks like there wasn't a taken branch
 146         if (pc > (ic_entry-1)->tag && pc <= (ic_entry-1)->tag + MAX_INSN_LENGTH)
 147           _mmu->refill_icache(pc, ic_entry);
 148       }
 149     }
 150     catch(trap_t& t)
 151     {
 152       take_trap(t, pc);
 153       n = instret;
 154     }
 155
 156     state.minstret += instret;
 157     n -= instret;
 158   }
 159 }