Add Smcntrpmf functionality

If Smcntrpmf is enabled, mcycle / minstret increment only if counting
for the privilege level isn't inhibited in mcyclecfg / minstretcfg.

5 files changed, 88 insertions, 7 deletions

diff --git a/disasm/isa_parser.cc b/disasm/isa_parser.cc
index f4d9da4..d5dc439 100644
--- a/disasm/isa_parser.cc
+++ b/disasm/isa_parser.cc
@@ -290,6 +290,8 @@ isa_parser_t::isa_parser_t(const char* str, const char *priv)
       extension_table[EXT_SMCSRIND] = true;
     } else if (ext_str == "sscsrind") {
       extension_table[EXT_SSCSRIND] = true;
+    } else if (ext_str == "smcntrpmf") {
+      extension_table[EXT_SMCNTRPMF] = true;
     } else if (ext_str[0] == 'x') {
       extension_table['X'] = true;
       if (ext_str.size() == 1) {
diff --git a/riscv/csrs.cc b/riscv/csrs.cc
index 9849ea2..e3b5ad4 100644
--- a/riscv/csrs.cc
+++ b/riscv/csrs.cc
@@ -999,9 +999,10 @@ bool virtualized_satp_csr_t::unlogged_write(const reg_t val) noexcept {
 }
 
 // implement class wide_counter_csr_t
-wide_counter_csr_t::wide_counter_csr_t(processor_t* const proc, const reg_t addr):
+wide_counter_csr_t::wide_counter_csr_t(processor_t* const proc, const reg_t addr, smcntrpmf_csr_t_p config_csr):
   csr_t(proc, addr),
-  val(0) {
+  val(0),
+  config_csr(config_csr) {
 }
 
 reg_t wide_counter_csr_t::read() const noexcept {
@@ -1009,7 +1010,11 @@ reg_t wide_counter_csr_t::read() const noexcept {
 }
 
 void wide_counter_csr_t::bump(const reg_t howmuch) noexcept {
-  val += howmuch;  // to keep log reasonable size, don't log every bump
+  if (is_counting_enabled()) {
+    val += howmuch;  // to keep log reasonable size, don't log every bump
+  }
+  // Clear cached value
+  config_csr->reset_prev();
 }
 
 bool wide_counter_csr_t::unlogged_write(const reg_t val) noexcept {
@@ -1018,7 +1023,10 @@ bool wide_counter_csr_t::unlogged_write(const reg_t val) noexcept {
   // takes precedence over the increment to instret.  However, Spike
   // unconditionally increments instret after executing an instruction.
   // Correct for this artifact by decrementing instret here.
-  this->val--;
+  // Ensure that Smctrpmf hasn't disabled counting.
+  if (is_counting_enabled()) {
+    this->val--;
+  }
   return true;
 }
 
@@ -1027,6 +1035,20 @@ reg_t wide_counter_csr_t::written_value() const noexcept {
   return this->val + 1;
 }
 
+// Returns true if counting is not inhibited by Smcntrpmf.
+// Note that minstretcfg / mcyclecfg / mhpmevent* share the same inhibit bits.
+bool wide_counter_csr_t::is_counting_enabled() const noexcept {
+  auto prv = state->prv_changed ? state->prev_prv : state->prv;
+  auto v = state->v_changed ? state->v : state->prev_v;
+  auto mask = MHPMEVENT_MINH;
+  if (prv == PRV_S) {
+    mask = v ? MHPMEVENT_VSINH : MHPMEVENT_SINH;
+  } else if (prv == PRV_U) {
+    mask = v ? MHPMEVENT_VUINH : MHPMEVENT_UINH;
+  }
+  return (config_csr->read_prev() & mask) == 0;
+}
+
 // implement class time_counter_csr_t
 time_counter_csr_t::time_counter_csr_t(processor_t* const proc, const reg_t addr):
   csr_t(proc, addr),
@@ -1649,3 +1671,20 @@ csr_t_p sscsrind_reg_csr_t::get_reg() const noexcept {
 void sscsrind_reg_csr_t::add_ireg_proxy(const reg_t iselect_value, csr_t_p csr) {
   ireg_proxy[iselect_value] = csr;
 }
+
+smcntrpmf_csr_t::smcntrpmf_csr_t(processor_t* const proc, const reg_t addr, const reg_t mask, const reg_t init) : masked_csr_t(proc, addr, mask, init) {
+}
+
+reg_t smcntrpmf_csr_t::read_prev() const noexcept {
+  reg_t val = prev_val.value_or(read());
+  return val;
+}
+
+void smcntrpmf_csr_t::reset_prev() noexcept {
+  prev_val.reset();
+}
+
+bool smcntrpmf_csr_t::unlogged_write(const reg_t val) noexcept {
+  prev_val = read();
+  return masked_csr_t::unlogged_write(val);
+}
diff --git a/riscv/csrs.h b/riscv/csrs.h
index cf48673..5ca7e15 100644
--- a/riscv/csrs.h
+++ b/riscv/csrs.h
@@ -15,6 +15,8 @@
 // For access_type:
 #include "memtracer.h"
 #include <cassert>
+// For std::optional
+#include <optional>
 
 class processor_t;
 struct state_t;
@@ -516,12 +518,16 @@ class virtualized_satp_csr_t: public virtualized_csr_t {
   satp_csr_t_p orig_satp;
 };
 
+// Forward declaration
+class smcntrpmf_csr_t;
+typedef std::shared_ptr<smcntrpmf_csr_t> smcntrpmf_csr_t_p;
+
 // For minstret and mcycle, which are always 64 bits, but in RV32 are
 // split into high and low halves. The first class always holds the
 // full 64-bit value.
 class wide_counter_csr_t: public csr_t {
  public:
-  wide_counter_csr_t(processor_t* const proc, const reg_t addr);
+  wide_counter_csr_t(processor_t* const proc, const reg_t addr, smcntrpmf_csr_t_p config_csr);
   // Always returns full 64-bit value
   virtual reg_t read() const noexcept override;
   void bump(const reg_t howmuch) noexcept;
@@ -529,7 +535,9 @@ class wide_counter_csr_t: public csr_t {
   virtual bool unlogged_write(const reg_t val) noexcept override;
   virtual reg_t written_value() const noexcept override;
  private:
+  bool is_counting_enabled() const noexcept;
   reg_t val;
+  smcntrpmf_csr_t_p config_csr;
 };
 
 typedef std::shared_ptr<wide_counter_csr_t> wide_counter_csr_t_p;
@@ -822,4 +830,16 @@ class sscsrind_reg_csr_t : public csr_t {
   csr_t_p get_reg() const noexcept;
 };
 
+// smcntrpmf_csr_t caches the previous state of the CSR in case a CSRW instruction
+// modifies the state that should not be immediately visible to bump()
+class smcntrpmf_csr_t : public masked_csr_t {
+ public:
+  smcntrpmf_csr_t(processor_t* const proc, const reg_t addr, const reg_t mask, const reg_t init);
+  reg_t read_prev() const noexcept;
+  void reset_prev() noexcept;
+ protected:
+  virtual bool unlogged_write(const reg_t val) noexcept override;
+ private:
+  std::optional<reg_t> prev_val;
+};
 #endif
diff --git a/riscv/isa_parser.h b/riscv/isa_parser.h
index bba5a91..f955e16 100644
--- a/riscv/isa_parser.h
+++ b/riscv/isa_parser.h
@@ -79,6 +79,7 @@ typedef enum {
   EXT_INTERNAL_ZFH_MOVE,
   EXT_SMCSRIND,
   EXT_SSCSRIND,
+  EXT_SMCNTRPMF,
   NUM_ISA_EXTENSIONS
 } isa_extension_t;
 
diff --git a/riscv/processor.cc b/riscv/processor.cc
index 3126433..0704d8c 100644
--- a/riscv/processor.cc
+++ b/riscv/processor.cc
@@ -219,8 +219,15 @@ void state_t::reset(processor_t* const proc, reg_t max_isa)
   csrmap[CSR_MSCRATCH] = std::make_shared<basic_csr_t>(proc, CSR_MSCRATCH, 0);
   csrmap[CSR_MTVEC] = mtvec = std::make_shared<tvec_csr_t>(proc, CSR_MTVEC);
   csrmap[CSR_MCAUSE] = mcause = std::make_shared<cause_csr_t>(proc, CSR_MCAUSE);
-  minstret = std::make_shared<wide_counter_csr_t>(proc, CSR_MINSTRET);
-  mcycle = std::make_shared<wide_counter_csr_t>(proc, CSR_MCYCLE);
+
+  auto smcntrpmf_enabled = proc->extension_enabled_const(EXT_SMCNTRPMF);
+  const reg_t mask = smcntrpmf_enabled ? MHPMEVENT_MINH | MHPMEVENT_SINH |
+                                         MHPMEVENT_UINH | MHPMEVENT_VSINH | MHPMEVENT_VUINH : 0;
+  auto minstretcfg = std::make_shared<smcntrpmf_csr_t>(proc, CSR_MINSTRETCFG, mask, 0);
+  auto mcyclecfg = std::make_shared<smcntrpmf_csr_t>(proc, CSR_MCYCLECFG, mask, 0);
+
+  minstret = std::make_shared<wide_counter_csr_t>(proc, CSR_MINSTRET, minstretcfg);
+  mcycle = std::make_shared<wide_counter_csr_t>(proc, CSR_MCYCLE, mcyclecfg);
   time = std::make_shared<time_counter_csr_t>(proc, CSR_TIME);
   if (proc->extension_enabled_const(EXT_ZICNTR)) {
     csrmap[CSR_INSTRET] = std::make_shared<counter_proxy_csr_t>(proc, CSR_INSTRET, minstret);
@@ -566,6 +573,18 @@ void state_t::reset(processor_t* const proc, reg_t max_isa)
     }
   }
 
+  if (smcntrpmf_enabled) {
+      if (xlen == 32) {
+        csrmap[CSR_MCYCLECFG] = std::make_shared<rv32_low_csr_t>(proc, CSR_MCYCLECFG, mcyclecfg);
+        csrmap[CSR_MCYCLECFGH] = std::make_shared<rv32_high_csr_t>(proc, CSR_MCYCLECFGH, mcyclecfg);
+        csrmap[CSR_MINSTRETCFG] = std::make_shared<rv32_low_csr_t>(proc, CSR_MINSTRETCFG, minstretcfg);
+        csrmap[CSR_MINSTRETCFGH] = std::make_shared<rv32_high_csr_t>(proc, CSR_MINSTRETCFGH, minstretcfg);
+      } else {
+        csrmap[CSR_MCYCLECFG] = mcyclecfg;
+        csrmap[CSR_MINSTRETCFG] = minstretcfg;
+      }
+  }
+
   serialized = false;
 
   log_reg_write.clear();