Merge pull request #247 from OpenXiangShan/skipperfcntcsr

arch-riscv: skip diff when reading perfCnt CSRs
OpenXiangShan · Jan 2, 2025 · 5182ebd · 5182ebd
2 parents 0b08af4 + 8fa8f5b
commit 5182ebd
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Showing 2 changed files with 38 additions and 5 deletions.
diff --git a/src/cpu/difftest.cc b/src/cpu/difftest.cc
@@ -5,6 +5,7 @@
 #include <cstdio>
 #include <cstdlib>
 
+#include "arch/riscv/regs/misc.hh"
 #include "base/trace.hh"
 #include "cpu/nemu_common.hh"
 #include "debug/ValueCommit.hh"
@@ -34,10 +35,36 @@ const char *reg_name[] = {
     "v30",    "v31"
     };
 
-const std::vector<uint64_t> skipCSRs = {
-  0xb0200073,
-  0xb0000073
-};
+std::vector<uint64_t> skipCSRs;
+
+// CSR op Encoding:
+//     #12
+// | csrName | 0000 | 0000 | 0000 | 0111 | 0011 |
+#define GetCSROPInstCode(csrName) ((csrName << 20) | 0x73UL)
+
+void
+skipPerfCntCsr()
+{
+    skipCSRs.push_back(GetCSROPInstCode(gem5::RiscvISA::CSR_MCYCLE));
+    skipCSRs.push_back(GetCSROPInstCode(gem5::RiscvISA::CSR_MINSTRET));
+
+    for (uint64_t counter = gem5::RiscvISA::CSR_MMHPMCOUNTER3;
+                  counter <= gem5::RiscvISA::CSR_MMHPMCOUNTER31; counter++) {
+        skipCSRs.push_back(GetCSROPInstCode(counter));
+    }
+    for (uint64_t counter = gem5::RiscvISA::CSR_MHPMCOUNTER03;
+                  counter <= gem5::RiscvISA::CSR_MHPMCOUNTER31; counter++) {
+        skipCSRs.push_back(GetCSROPInstCode(counter));
+    }
+    for (uint64_t counter = gem5::RiscvISA::CSR_MMCOUNTINHIBIT;
+                  counter <= gem5::RiscvISA::CSR_MHPMEVENT31; counter++) {
+        skipCSRs.push_back(GetCSROPInstCode(counter));
+    }
+    for (uint64_t counter = gem5::RiscvISA::CSR_CYCLE;
+                  counter <= gem5::RiscvISA::CSR_HPMCOUNTER31; counter++) {
+        skipCSRs.push_back(GetCSROPInstCode(counter));
+    }
+}
 
 NemuProxy::NemuProxy(int coreid, const char *ref_so, bool enable_sdcard_diff, bool enable_mem_dedup, bool multi_core)
 {
@@ -100,6 +127,8 @@ NemuProxy::NemuProxy(int coreid, const char *ref_so, bool enable_sdcard_diff, bo
         assert(sdcard_init);
     }
 
+    skipPerfCntCsr();
+
     auto nemu_init = (void (*)(void))dlsym(handle, "difftest_init");
     assert(nemu_init);
 
@@ -171,6 +200,8 @@ SpikeProxy::SpikeProxy(int coreid, const char *ref_so, bool enable_sdcard_diff)
 
     assert(!enable_sdcard_diff);
 
+    skipPerfCntCsr();
+
     auto nemu_init = (void (*)(void))dlsym(handle, "difftest_init");
     assert(nemu_init);
 

diff --git a/src/cpu/difftest.hh b/src/cpu/difftest.hh
@@ -228,7 +228,9 @@ enum DiffAt
     ValueDiff,
 };
 
-extern const std::vector<uint64_t> skipCSRs;
+void skipPerfCntCsr();
+
+extern std::vector<uint64_t> skipCSRs;
 
 extern uint8_t *pmemStart;
 extern uint64_t pmemSize;