riscv64,intr: add longjmp_raise_intr()

src/isa/riscv64/exec/exec.c

 #include "cpu/exec.h"
 #include "all-instr.h"
+#include <setjmp.h>
 
 static make_EHelper(load) {
   static OpcodeEntry table [8] = {
@@ -136,6 +137,15 @@ static OpcodeEntry rvc_table [3][8] = {
 };
 
 void isa_exec(vaddr_t *pc) {
+  extern jmp_buf intr_buf;
+  int setjmp_ret;
+  if ((setjmp_ret = setjmp(intr_buf)) != 0) {
+    int exception = setjmp_ret - 1;
+    void raise_intr(word_t, vaddr_t);
+    raise_intr(exception, cpu.pc);
+    return;
+  }
+
   decinfo.isa.instr.val = instr_fetch(pc, 4);
   if (decinfo.isa.instr.opcode1_0 == 0x3) {
     idex(pc, &opcode_table[decinfo.isa.instr.opcode6_2]);

src/isa/riscv64/intr.c

 #include "rtl/rtl.h"
 #include "csr.h"
+#include <setjmp.h>
 
 #define INTR_BIT (1ULL << 63)
 enum {
@@ -57,3 +58,8 @@ bool isa_query_intr(void) {
   }
   return false;
 }
+
+jmp_buf intr_buf;
+void longjmp_raise_intr(uint32_t NO) {
+  longjmp(intr_buf, NO + 1);
+}