target/xtensa: extract test for an illegal instruction

- TB flags: add XTENSA_TBFLAG_CWOE that corresponds to the architectural
  CWOE state;
- entry: move CWOE check from the helper to the test_ill_entry;
- retw: move CWOE check from the helper to the test_ill_retw;
- separate instruction disassembly loop and translation loop; save
  disassembly results in local array;

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

target/xtensa/cpu.h

@@ -217,6 +217,7 @@ enum {
 #define MEMCTL_IL0EN 0x1
 
 #define MAX_INSN_LENGTH 64
+#define MAX_INSN_SLOTS 32
 #define MAX_OPCODE_ARGS 16
 #define MAX_NAREG 64
 #define MAX_NINTERRUPT 32
@@ -347,11 +348,34 @@ typedef struct XtensaMemory {
 typedef struct DisasContext DisasContext;
 typedef void (*XtensaOpcodeOp)(DisasContext *dc, const uint32_t arg[],
                                const uint32_t par[]);
+typedef bool (*XtensaOpcodeBoolTest)(DisasContext *dc,
+                                     const uint32_t arg[],
+                                     const uint32_t par[]);
+
+enum {
+    XTENSA_OP_ILL = 0x1,
+    XTENSA_OP_PRIVILEGED = 0x2,
+    XTENSA_OP_SYSCALL = 0x4,
+    XTENSA_OP_DEBUG_BREAK = 0x8,
+
+    XTENSA_OP_OVERFLOW = 0x10,
+    XTENSA_OP_UNDERFLOW = 0x20,
+    XTENSA_OP_ALLOCA = 0x40,
+    XTENSA_OP_COPROCESSOR = 0x80,
+
+    XTENSA_OP_DIVIDE_BY_ZERO = 0x100,
+
+    XTENSA_OP_CHECK_INTERRUPTS = 0x200,
+    XTENSA_OP_EXIT_TB_M1 = 0x400,
+    XTENSA_OP_EXIT_TB_0 = 0x800,
+};
 
 typedef struct XtensaOpcodeOps {
     const char *name;
     XtensaOpcodeOp translate;
+    XtensaOpcodeBoolTest test_ill;
     const uint32_t *par;
+    uint32_t op_flags;
 } XtensaOpcodeOps;
 
 typedef struct XtensaOpcodeTranslators {
@@ -661,6 +685,7 @@ static inline int cpu_mmu_index(CPUXtensaState *env, bool ifetch)
 #define XTENSA_TBFLAG_WINDOW_MASK 0x18000
 #define XTENSA_TBFLAG_WINDOW_SHIFT 15
 #define XTENSA_TBFLAG_YIELD 0x20000
+#define XTENSA_TBFLAG_CWOE 0x40000
 
 static inline void cpu_get_tb_cpu_state(CPUXtensaState *env, target_ulong *pc,
         target_ulong *cs_base, uint32_t *flags)
@@ -698,7 +723,7 @@ static inline void cpu_get_tb_cpu_state(CPUXtensaState *env, target_ulong *pc,
             (env->sregs[WINDOW_BASE] + 1);
         uint32_t w = ctz32(windowstart | 0x8);
 
-        *flags |= w << XTENSA_TBFLAG_WINDOW_SHIFT;
+        *flags |= (w << XTENSA_TBFLAG_WINDOW_SHIFT) | XTENSA_TBFLAG_CWOE;
     } else {
         *flags |= 3 << XTENSA_TBFLAG_WINDOW_SHIFT;
     }

target/xtensa/helper.c

@@ -57,12 +57,18 @@ static void init_libisa(XtensaConfig *config)
 {
     unsigned i, j;
     unsigned opcodes;
+    unsigned formats;
 
     config->isa = xtensa_isa_init(config->isa_internal, NULL, NULL);
     assert(xtensa_isa_maxlength(config->isa) <= MAX_INSN_LENGTH);
     opcodes = xtensa_isa_num_opcodes(config->isa);
+    formats = xtensa_isa_num_formats(config->isa);
     config->opcode_ops = g_new(XtensaOpcodeOps *, opcodes);
 
+    for (i = 0; i < formats; ++i) {
+        assert(xtensa_format_num_slots(config->isa, i) <= MAX_INSN_SLOTS);
+    }
+
     for (i = 0; i < opcodes; ++i) {
         const char *opc_name = xtensa_opcode_name(config->isa, i);
         XtensaOpcodeOps *ops = NULL;

target/xtensa/helper.h

@@ -5,6 +5,7 @@ DEF_HELPER_3(debug_exception, noreturn, env, i32, i32)
 
 DEF_HELPER_2(wsr_windowbase, void, env, i32)
 DEF_HELPER_4(entry, void, env, i32, i32, i32)
+DEF_HELPER_2(test_ill_retw, void, env, i32)
 DEF_HELPER_2(retw, i32, env, i32)
 DEF_HELPER_2(rotw, void, env, i32)
 DEF_HELPER_3(window_check, noreturn, env, i32, i32)

target/xtensa/op_helper.c

@@ -253,22 +253,16 @@ void HELPER(wsr_windowbase)(CPUXtensaState *env, uint32_t v)
 void HELPER(entry)(CPUXtensaState *env, uint32_t pc, uint32_t s, uint32_t imm)
 {
     int callinc = (env->sregs[PS] & PS_CALLINC) >> PS_CALLINC_SHIFT;
-    if (s > 3 || ((env->sregs[PS] & (PS_WOE | PS_EXCM)) ^ PS_WOE) != 0) {
-        qemu_log_mask(LOG_GUEST_ERROR, "Illegal entry instruction(pc = %08x), PS = %08x\n",
-                      pc, env->sregs[PS]);
-        HELPER(exception_cause)(env, pc, ILLEGAL_INSTRUCTION_CAUSE);
-    } else {
-        uint32_t windowstart = xtensa_replicate_windowstart(env) >>
-            (env->sregs[WINDOW_BASE] + 1);
+    uint32_t windowstart = xtensa_replicate_windowstart(env) >>
+        (env->sregs[WINDOW_BASE] + 1);
 
-        if (windowstart & ((1 << callinc) - 1)) {
-            HELPER(window_check)(env, pc, callinc);
-        }
-        env->regs[(callinc << 2) | (s & 3)] = env->regs[s] - imm;
-        xtensa_rotate_window(env, callinc);
-        env->sregs[WINDOW_START] |=
-            windowstart_bit(env->sregs[WINDOW_BASE], env);
+    if (windowstart & ((1 << callinc) - 1)) {
+        HELPER(window_check)(env, pc, callinc);
     }
+    env->regs[(callinc << 2) | (s & 3)] = env->regs[s] - imm;
+    xtensa_rotate_window(env, callinc);
+    env->sregs[WINDOW_START] |=
+        windowstart_bit(env->sregs[WINDOW_BASE], env);
 }
 
 void HELPER(window_check)(CPUXtensaState *env, uint32_t pc, uint32_t w)
@@ -298,13 +292,12 @@ void HELPER(window_check)(CPUXtensaState *env, uint32_t pc, uint32_t w)
     }
 }
 
-uint32_t HELPER(retw)(CPUXtensaState *env, uint32_t pc)
+void HELPER(test_ill_retw)(CPUXtensaState *env, uint32_t pc)
 {
     int n = (env->regs[0] >> 30) & 0x3;
     int m = 0;
     uint32_t windowbase = windowbase_bound(env->sregs[WINDOW_BASE], env);
     uint32_t windowstart = env->sregs[WINDOW_START];
-    uint32_t ret_pc = 0;
 
     if (windowstart & windowstart_bit(windowbase - 1, env)) {
         m = 1;
@@ -314,33 +307,38 @@ uint32_t HELPER(retw)(CPUXtensaState *env, uint32_t pc)
         m = 3;
     }
 
-    if (n == 0 || (m != 0 && m != n) ||
-            ((env->sregs[PS] & (PS_WOE | PS_EXCM)) ^ PS_WOE) != 0) {
+    if (n == 0 || (m != 0 && m != n)) {
         qemu_log_mask(LOG_GUEST_ERROR, "Illegal retw instruction(pc = %08x), "
                       "PS = %08x, m = %d, n = %d\n",
                       pc, env->sregs[PS], m, n);
         HELPER(exception_cause)(env, pc, ILLEGAL_INSTRUCTION_CAUSE);
+    }
+}
+
+uint32_t HELPER(retw)(CPUXtensaState *env, uint32_t pc)
+{
+    int n = (env->regs[0] >> 30) & 0x3;
+    uint32_t windowbase = windowbase_bound(env->sregs[WINDOW_BASE], env);
+    uint32_t windowstart = env->sregs[WINDOW_START];
+    uint32_t ret_pc = 0;
+
+    ret_pc = (pc & 0xc0000000) | (env->regs[0] & 0x3fffffff);
+
+    xtensa_rotate_window(env, -n);
+    if (windowstart & windowstart_bit(env->sregs[WINDOW_BASE], env)) {
+        env->sregs[WINDOW_START] &= ~windowstart_bit(windowbase, env);
     } else {
-        int owb = windowbase;
+        /* window underflow */
+        env->sregs[PS] = (env->sregs[PS] & ~PS_OWB) |
+            (windowbase << PS_OWB_SHIFT) | PS_EXCM;
+        env->sregs[EPC1] = env->pc = pc;
 
-        ret_pc = (pc & 0xc0000000) | (env->regs[0] & 0x3fffffff);
-
-        xtensa_rotate_window(env, -n);
-        if (windowstart & windowstart_bit(env->sregs[WINDOW_BASE], env)) {
-            env->sregs[WINDOW_START] &= ~windowstart_bit(owb, env);
-        } else {
-            /* window underflow */
-            env->sregs[PS] = (env->sregs[PS] & ~PS_OWB) |
-                (windowbase << PS_OWB_SHIFT) | PS_EXCM;
-            env->sregs[EPC1] = env->pc = pc;
-
-            if (n == 1) {
-                HELPER(exception)(env, EXC_WINDOW_UNDERFLOW4);
-            } else if (n == 2) {
-                HELPER(exception)(env, EXC_WINDOW_UNDERFLOW8);
-            } else if (n == 3) {
-                HELPER(exception)(env, EXC_WINDOW_UNDERFLOW12);
-            }
+        if (n == 1) {
+            HELPER(exception)(env, EXC_WINDOW_UNDERFLOW4);
+        } else if (n == 2) {
+            HELPER(exception)(env, EXC_WINDOW_UNDERFLOW8);
+        } else if (n == 3) {
+            HELPER(exception)(env, EXC_WINDOW_UNDERFLOW12);
         }
     }
     return ret_pc;