pk: remove vestigial trapframe_t::insn field

This assumes that stval is populated with the opcode on illegal
instruction exceptions.  But since we're only using the opcode for
error reporting, it's OK if this assumption is violated.

pk/console.c

@@ -48,8 +48,7 @@ void dump_tf(trapframe_t* tf)
     for(int j = 0; j < 4; j++)
       printk("%s %lx%c", get_regname(i+j), tf->gpr[i+j], j < 3 ? ' ' : '\n');
   }
-  printk("pc %lx va %lx insn       %x sr %lx\n", tf->epc, tf->badvaddr,
-         (uint32_t)tf->insn, tf->status);
+  printk("pc %lx va/inst %lx sr %lx\n", tf->epc, tf->badvaddr, tf->status);
 }
 
 void do_panic(const char* s, ...)

pk/entry.S

@@ -47,10 +47,6 @@
   STORE  t1,33*REGBYTES(x2)
   STORE  t2,34*REGBYTES(x2)
   STORE  t3,35*REGBYTES(x2)
-
-  # get faulting insn, if it wasn't a fetch-related trap
-  li x5,-1
-  STORE x5,36*REGBYTES(x2)
 1:
   .endm
 

pk/handlers.c

@@ -25,13 +25,6 @@ static void handle_store_access_fault(trapframe_t *tf)
 
 static void handle_illegal_instruction(trapframe_t* tf)
 {
-  tf->insn = *(uint16_t*)tf->epc;
-  int len = insn_len(tf->insn);
-  if (len == 4)
-    tf->insn |= ((uint32_t)*(uint16_t*)(tf->epc + 2) << 16);
-  else
-    kassert(len == 2);
-
   dump_tf(tf);
   panic("An illegal instruction was executed!");
 }

pk/pk.h

@@ -17,7 +17,6 @@ typedef struct
   long epc;
   long badvaddr;
   long cause;
-  long insn;
 } trapframe_t;
 
 #define panic(s,...) do { do_panic(s"\n", ##__VA_ARGS__); } while(0)