Added start in mips16 mode support, and unit test for it - on dev branch (#2089)

Co-authored-by: ZakDanger <[email protected]>

Author: ZakDanger

qemu/target/mips/unicorn.c

@@ -19,12 +19,18 @@ MIPSCPU *cpu_mips_init(struct uc_struct *uc);
 
 static void mips_set_pc(struct uc_struct *uc, uint64_t address)
 {
-    ((CPUMIPSState *)uc->cpu->env_ptr)->active_tc.PC = address;
+    ((CPUMIPSState *)uc->cpu->env_ptr)->active_tc.PC = address & ~(uint64_t )1ULL;
+    if (address & 1) {
+        ((CPUMIPSState *)uc->cpu->env_ptr)->hflags |= MIPS_HFLAG_M16;
+    } else {
+        ((CPUMIPSState *)uc->cpu->env_ptr)->hflags &= ~(MIPS_HFLAG_M16);
+    }
 }
 
 static uint64_t mips_get_pc(struct uc_struct *uc)
 {
-    return ((CPUMIPSState *)uc->cpu->env_ptr)->active_tc.PC;
+    return ((CPUMIPSState *)uc->cpu->env_ptr)->active_tc.PC |
+        !!(((CPUMIPSState *)uc->cpu->env_ptr)->hflags & (MIPS_HFLAG_M16));
 }
 
 static void mips_release(void *ctx)
@@ -128,7 +134,12 @@ uc_err reg_write(void *_env, int mode, unsigned int regid, const void *value,
             break;
         case UC_MIPS_REG_PC:
             CHECK_REG_TYPE(mipsreg_t);
-            env->active_tc.PC = *(mipsreg_t *)value;
+            env->active_tc.PC = *(mipsreg_t *)value & ~1ULL;
+            if ((*(uint32_t *)value & 1)) {
+                env->hflags |= MIPS_HFLAG_M16;
+            } else {
+                env->hflags &= ~(MIPS_HFLAG_M16);
+            }
             *setpc = 1;
             break;
         case UC_MIPS_REG_CP0_CONFIG3:

tests/unit/test_mips.c

@@ -17,7 +17,7 @@ static void test_mips_el_ori(void)
     char code[] = "\x56\x34\x21\x34"; // ori $at, $at, 0x3456;
     int r_r1 = 0x6789;
 
-    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_32 | UC_MODE_LITTLE_ENDIAN, code,
+    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32 | UC_MODE_LITTLE_ENDIAN, code,
                     sizeof(code) - 1);
     OK(uc_reg_write(uc, UC_MIPS_REG_1, &r_r1));
 
@@ -36,7 +36,7 @@ static void test_mips_eb_ori(void)
     char code[] = "\x34\x21\x34\x56"; // ori $at, $at, 0x3456;
     int r_r1 = 0x6789;
 
-    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_32 | UC_MODE_BIG_ENDIAN, code,
+    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32 | UC_MODE_BIG_ENDIAN, code,
                     sizeof(code) - 1);
     OK(uc_reg_write(uc, UC_MIPS_REG_1, &r_r1));
 
@@ -56,7 +56,7 @@ static void test_mips_stop_at_branch(void)
         "\x02\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00"; // j 0x8; nop;
     int r_pc = 0x0;
 
-    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_32 | UC_MODE_LITTLE_ENDIAN, code,
+    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32 | UC_MODE_LITTLE_ENDIAN, code,
                     sizeof(code) - 1);
 
     // Execute one instruction with branch delay slot.
@@ -78,7 +78,7 @@ static void test_mips_stop_at_delay_slot(void)
         "\x02\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00"; // j 0x8; nop;
     int r_pc = 0x0;
 
-    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_32 | UC_MODE_LITTLE_ENDIAN, code,
+    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32 | UC_MODE_LITTLE_ENDIAN, code,
                     sizeof(code) - 1);
 
     // Stop at the delay slot by design.
@@ -99,7 +99,7 @@ static void test_mips_lwx_exception_issue_1314(void)
     char code[] = "\x0a\xc8\x79\x7e"; // lwx $t9, $t9($s3)
     int reg;
 
-    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_32 | UC_MODE_LITTLE_ENDIAN, code,
+    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32 | UC_MODE_LITTLE_ENDIAN, code,
                     sizeof(code) - 1);
     OK(uc_mem_map(uc, 0x10000, 0x4000, UC_PROT_ALL));
 
@@ -126,10 +126,31 @@ static void test_mips_lwx_exception_issue_1314(void)
     OK(uc_close(uc));
 }
 
+static void test_mips_mips16(void)
+{
+    uc_engine *uc;
+    char code[] = "\xC4\x6B\x49\xE3"; // li $v1, 0xC4;  addu $v0, $v1, $v0
+    int r_v0 = 0x6789;
+    int mips16_lowbit = 1;
+
+    uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32 | UC_MODE_LITTLE_ENDIAN, code,
+                    sizeof(code) - 1);
+    OK(uc_reg_write(uc, UC_MIPS_REG_V0, &r_v0));
+
+    OK(uc_emu_start(uc, code_start | mips16_lowbit, code_start + sizeof(code) - 1, 0, 0));
+
+    OK(uc_reg_read(uc, UC_MIPS_REG_V0, &r_v0));
+
+    TEST_CHECK(r_v0 == 0x684D);
+
+    OK(uc_close(uc));
+}
+
 TEST_LIST = {
     {"test_mips_stop_at_branch", test_mips_stop_at_branch},
     {"test_mips_stop_at_delay_slot", test_mips_stop_at_delay_slot},
     {"test_mips_el_ori", test_mips_el_ori},
     {"test_mips_eb_ori", test_mips_eb_ori},
     {"test_mips_lwx_exception_issue_1314", test_mips_lwx_exception_issue_1314},
+    {"test_mips_mips16", test_mips_mips16},
     {NULL, NULL}};