Support MIPS64 - write correct PC register width on uc_emu_start (#2111)

* Support mips64 - write correct pc register width on uc_emu_start

* Convert to UC_MODE_MIPS64

* Correctly select MIPS64 CPU model

* Simple 64-bit test - check it doesn't crash

* lint

* Comment

* Comment

* Add offset when indexing cpu model, makes tests work on older python

* Move test

* add PC check to test

* Fix test - add python version check

* Use RegressTest method for assert

qemu/target/mips/cpu.c

@@ -194,7 +194,12 @@ MIPSCPU *cpu_mips_init(struct uc_struct *uc)
     mips_cpu_initfn(uc, cs);
 
     env = &cpu->env;
-    env->cpu_model = &(mips_defs[uc->cpu_model]);
+    if(uc->mode & UC_MODE_MIPS64){
+        // 64-bit CPU models are defined in the array directly after 32-bit models
+        env->cpu_model = &(mips_defs[uc->cpu_model + UC_CPU_MIPS32_ENDING]);
+    } else {
+        env->cpu_model = &(mips_defs[uc->cpu_model]);
+    }
 
     if (env->cpu_model == NULL) {
         free(cpu);

tests/regress/mips64.py

@@ -0,0 +1,39 @@
+import sys
+import unittest
+import regress
+from unicorn import *
+from unicorn.mips_const import *
+
+
+class Mips64(regress.RegressTest):
+
+    @unittest.skipIf(sys.version_info < (3, 7), reason="requires python3.7 or higher")
+    def runTest(self):
+        # Two instructions:
+        #   daddu  $gp, $gp, $ra    # a 64-bit instruction. This is important - it ensures the selected CPU model is 64-bit, otherwise it would crash
+        #   move   $t1, $v0
+
+        code = b"\x03\x9f\xe0\x2d" + b"\x00\x40\x48\x25"
+
+        uc = Uc(UC_ARCH_MIPS, UC_MODE_MIPS64 + UC_MODE_BIG_ENDIAN)
+        # For MIPS64 to be able to reference addresses >= 0x80000000, you need to enable the virtual TLB
+        # See https://github.com/unicorn-engine/unicorn/pull/2111 for more details
+        uc.ctl_set_tlb_mode(UC_TLB_VIRTUAL)
+
+        ADDRESS = 0x0120003000
+
+        uc.reg_write(UC_MIPS_REG_PC, ADDRESS)
+        uc.reg_write(UC_MIPS_REG_GP, 0x123)
+        uc.reg_write(UC_MIPS_REG_RA, 0x456)
+
+        uc.mem_map(ADDRESS, 4 * 1024)
+        uc.mem_write(ADDRESS, code)
+
+        # This will raise an exception if MIPS64 fails
+        uc.emu_start(ADDRESS, 0, count=2)
+
+        self.assertEqual(uc.reg_read(UC_MIPS_REG_PC),0x0120003000 + 8)
+
+
+if __name__ == '__main__':
+    regress.main()

uc.c

@@ -1020,8 +1020,11 @@ uc_err uc_emu_start(uc_engine *uc, uint64_t begin, uint64_t until,
 #endif
 #ifdef UNICORN_HAS_MIPS
     case UC_ARCH_MIPS:
-        // TODO: MIPS32/MIPS64/BIGENDIAN etc
-        uc_reg_write(uc, UC_MIPS_REG_PC, &begin_pc32);
+        if (uc->mode & UC_MODE_MIPS64) {
+            uc_reg_write(uc, UC_MIPS_REG_PC, &begin);
+        } else {
+            uc_reg_write(uc, UC_MIPS_REG_PC, &begin_pc32);
+        }
         break;
 #endif
 #ifdef UNICORN_HAS_SPARC