Don't assume existence of uarch counters

machine/encoding.h

@@ -629,23 +629,6 @@
 #define CSR_CYCLE 0xc00
 #define CSR_TIME 0xc01
 #define CSR_INSTRET 0xc02
-#define CSR_STATS 0xc0
-#define CSR_UARCH0 0xcc0
-#define CSR_UARCH1 0xcc1
-#define CSR_UARCH2 0xcc2
-#define CSR_UARCH3 0xcc3
-#define CSR_UARCH4 0xcc4
-#define CSR_UARCH5 0xcc5
-#define CSR_UARCH6 0xcc6
-#define CSR_UARCH7 0xcc7
-#define CSR_UARCH8 0xcc8
-#define CSR_UARCH9 0xcc9
-#define CSR_UARCH10 0xcca
-#define CSR_UARCH11 0xccb
-#define CSR_UARCH12 0xccc
-#define CSR_UARCH13 0xccd
-#define CSR_UARCH14 0xcce
-#define CSR_UARCH15 0xccf
 #define CSR_SSTATUS 0x100
 #define CSR_SIE 0x104
 #define CSR_STVEC 0x105
@@ -951,23 +934,6 @@ DECLARE_CSR(fcsr, CSR_FCSR)
 DECLARE_CSR(cycle, CSR_CYCLE)
 DECLARE_CSR(time, CSR_TIME)
 DECLARE_CSR(instret, CSR_INSTRET)
-DECLARE_CSR(stats, CSR_STATS)
-DECLARE_CSR(uarch0, CSR_UARCH0)
-DECLARE_CSR(uarch1, CSR_UARCH1)
-DECLARE_CSR(uarch2, CSR_UARCH2)
-DECLARE_CSR(uarch3, CSR_UARCH3)
-DECLARE_CSR(uarch4, CSR_UARCH4)
-DECLARE_CSR(uarch5, CSR_UARCH5)
-DECLARE_CSR(uarch6, CSR_UARCH6)
-DECLARE_CSR(uarch7, CSR_UARCH7)
-DECLARE_CSR(uarch8, CSR_UARCH8)
-DECLARE_CSR(uarch9, CSR_UARCH9)
-DECLARE_CSR(uarch10, CSR_UARCH10)
-DECLARE_CSR(uarch11, CSR_UARCH11)
-DECLARE_CSR(uarch12, CSR_UARCH12)
-DECLARE_CSR(uarch13, CSR_UARCH13)
-DECLARE_CSR(uarch14, CSR_UARCH14)
-DECLARE_CSR(uarch15, CSR_UARCH15)
 DECLARE_CSR(sstatus, CSR_SSTATUS)
 DECLARE_CSR(sie, CSR_SIE)
 DECLARE_CSR(stvec, CSR_STVEC)

pk/handlers.c

@@ -14,6 +14,13 @@ static void handle_illegal_instruction(trapframe_t* tf)
   else
     kassert(len == 2);
 
+  // supply 0 for unimplemented uarch counters
+  if ((tf->insn & (MASK_CSRRS | 0xcc0U<<20)) == (MATCH_CSRRS | 0xcc0U<<20)) {
+    tf->gpr[(tf->insn >> 7) & 0x1f] = 0;
+    tf->epc += 4;
+    return;
+  }
+
   dump_tf(tf);
   panic("An illegal instruction was executed!");
 }

pk/pk.c

@@ -4,12 +4,45 @@
 #include "elf.h"
 #include "mtrap.h"
 #include "frontend.h"
+#include <stdbool.h>
 
 elf_info current;
 
-int uarch_counters_enabled;
-long uarch_counters[NUM_COUNTERS];
-char* uarch_counter_names[NUM_COUNTERS];
+#define NUM_COUNTERS 18
+static int uarch_counters_enabled;
+static long uarch_counters[NUM_COUNTERS];
+static char* uarch_counter_names[NUM_COUNTERS];
+
+static void read_uarch_counters(bool dump)
+{
+  if (!uarch_counters_enabled)
+    return;
+
+  size_t i = 0;
+  #define READ_CTR(name) do { \
+    while (i >= NUM_COUNTERS) ; \
+    long csr = read_csr(name); \
+    if (dump && csr) printk("%s = %ld\n", #name, csr - uarch_counters[i]); \
+    uarch_counters[i++] = csr; \
+  } while (0)
+  READ_CTR(0xcc0); READ_CTR(0xcc1); READ_CTR(0xcc2);
+  READ_CTR(0xcc3); READ_CTR(0xcc4); READ_CTR(0xcc5);
+  READ_CTR(0xcc6); READ_CTR(0xcc7); READ_CTR(0xcc8);
+  READ_CTR(0xcc9); READ_CTR(0xcca); READ_CTR(0xccb);
+  READ_CTR(0xccc); READ_CTR(0xccd); READ_CTR(0xcce);
+  READ_CTR(0xccf); READ_CTR(cycle); READ_CTR(instret);
+  #undef READ_CTR
+}
+
+static void start_uarch_counters()
+{
+  read_uarch_counters(false);
+}
+
+void dump_uarch_counters()
+{
+  read_uarch_counters(true);
+}
 
 static void handle_option(const char* s)
 {
@@ -20,7 +53,6 @@ static void handle_option(const char* s)
       break;
 
     case 'c': // print uarch counters upon termination
-              // If your HW doesn't support uarch counters, then don't use this flag!
       uarch_counters_enabled = 1;
       break;
 
@@ -116,22 +148,7 @@ static void run_loaded_program(size_t argc, char** argv, uintptr_t kstack_top)
   if (current.t0) // start timer if so requested
     current.t0 = rdcycle();
 
-  if (uarch_counters_enabled) { // start tracking the uarch counters if requested
-    size_t i = 0;
-    #define READ_CTR_INIT(name) do { \
-      while (i >= NUM_COUNTERS) ; \
-      long csr = read_csr(name); \
-      uarch_counters[i++] = csr; \
-    } while (0)
-    READ_CTR_INIT(cycle);   READ_CTR_INIT(instret);
-    READ_CTR_INIT(uarch0);  READ_CTR_INIT(uarch1);  READ_CTR_INIT(uarch2);
-    READ_CTR_INIT(uarch3);  READ_CTR_INIT(uarch4);  READ_CTR_INIT(uarch5);
-    READ_CTR_INIT(uarch6);  READ_CTR_INIT(uarch7);  READ_CTR_INIT(uarch8);
-    READ_CTR_INIT(uarch9);  READ_CTR_INIT(uarch10); READ_CTR_INIT(uarch11);
-    READ_CTR_INIT(uarch12); READ_CTR_INIT(uarch13); READ_CTR_INIT(uarch14);
-    READ_CTR_INIT(uarch15);
-    #undef READ_CTR_INIT
-  }
+  start_uarch_counters();
 
   trapframe_t tf;
   init_tf(&tf, current.entry, stack_top);

pk/pk.h

@@ -35,6 +35,7 @@ int vsnprintf(char* out, size_t n, const char* s, va_list vl);
 int snprintf(char* out, size_t n, const char* s, ...);
 void start_user(trapframe_t* tf) __attribute__((noreturn));
 void dump_tf(trapframe_t*);
+void dump_uarch_counters();
 
 static inline int insn_len(long insn)
 {
@@ -43,11 +44,6 @@ static inline int insn_len(long insn)
 
 #define ARRAY_SIZE(x) (sizeof(x)/sizeof((x)[0]))
 
-#define NUM_COUNTERS (18)
-extern int uarch_counters_enabled;
-extern long uarch_counters[NUM_COUNTERS];
-extern char* uarch_counter_names[NUM_COUNTERS];
-
 #ifdef __cplusplus
 }
 #endif

pk/syscall.c

@@ -17,31 +17,7 @@ void sys_exit(int code)
 {
   if (current.t0)
     printk("%ld cycles\n", rdcycle() - current.t0);
-
-  if (uarch_counters_enabled) {
-    size_t i = 0;
-    #define READ_CTR_FINI(name) do { \
-      while (i >= NUM_COUNTERS) ; \
-      long csr = read_csr(name); \
-      csr -= uarch_counters[i]; uarch_counter_names[i] = #name; \
-      uarch_counters[i++] = csr; \
-    } while (0)
-    READ_CTR_FINI(cycle);   READ_CTR_FINI(instret);
-    READ_CTR_FINI(uarch0);  READ_CTR_FINI(uarch1);  READ_CTR_FINI(uarch2);
-    READ_CTR_FINI(uarch3);  READ_CTR_FINI(uarch4);  READ_CTR_FINI(uarch5);
-    READ_CTR_FINI(uarch6);  READ_CTR_FINI(uarch7);  READ_CTR_FINI(uarch8);
-    READ_CTR_FINI(uarch9);  READ_CTR_FINI(uarch10); READ_CTR_FINI(uarch11);
-    READ_CTR_FINI(uarch12); READ_CTR_FINI(uarch13); READ_CTR_FINI(uarch14);
-    READ_CTR_FINI(uarch15);
-    #undef READ_CTR_FINI
-
-    for (int i = 0; i < NUM_COUNTERS; i++) {
-      if (uarch_counters[i]) {
-        printk("%s = %ld\n", uarch_counter_names[i], uarch_counters[i]);
-      }
-    }
-  }
-
+  dump_uarch_counters();
   shutdown(code);
 }