target/arm: Convert RFE and SRS

Backports commit 885782a78c6d05932c5d8f463dc50fc8312e3eb9 from qemu

qemu/target/arm/a32-uncond.decode

@@ -29,3 +29,11 @@
 %imm24h          0:s24 24:1 !function=times_2
 
 BLX_i            1111 101 . ........................          &i imm=%imm24h
+
+# System Instructions
+
+&rfe             rn w pu
+&srs             mode w pu
+
+RFE              1111 100 pu:2 0 w:1 1 rn:4 0000 1010 0000 0000   &rfe
+SRS              1111 100 pu:2 1 w:1 0 1101 0000 0101 000 mode:5  &srs

qemu/target/arm/t32.decode

@@ -582,6 +582,18 @@ STM_t32          1110 1001 00.0 .... ................         @ldstm i=0 b=1
 LDM_t32          1110 1000 10.1 .... ................         @ldstm i=1 b=0
 LDM_t32          1110 1001 00.1 .... ................         @ldstm i=0 b=1
 
+&rfe             !extern rn w pu
+@rfe             .... .... .. w:1 . rn:4 ................     &rfe
+
+RFE              1110 1000 00.1 .... 1100000000000000         @rfe pu=2
+RFE              1110 1001 10.1 .... 1100000000000000         @rfe pu=1
+
+&srs             !extern mode w pu
+@srs             .... .... .. w:1 . .... ........... mode:5   &srs
+
+SRS              1110 1000 00.0 1101 1100 0000 000. ....      @srs pu=2
+SRS              1110 1001 10.0 1101 1100 0000 000. ....      @srs pu=1
+
 # Branches
 
 %imm24           26:s1 13:1 11:1 16:10 0:11 !function=t32_branch24

qemu/target/arm/translate.c

@@ -10429,6 +10429,59 @@ static bool trans_SVC(DisasContext *s, arg_SVC *a)
     return true;
 }
 
+/*
+ * Unconditional system instructions
+ */
+
+static bool trans_RFE(DisasContext *s, arg_RFE *a)
+{
+    static const int8_t pre_offset[4] = {
+        /* DA */ -4, /* IA */ 0, /* DB */ -8, /* IB */ 4
+    };
+    static const int8_t post_offset[4] = {
+        /* DA */ -8, /* IA */ 4, /* DB */ -4, /* IB */ 0
+    };
+    TCGContext *tcg_ctx = s->uc->tcg_ctx;
+    TCGv_i32 addr, t1, t2;
+
+    if (!ENABLE_ARCH_6 || arm_dc_feature(s, ARM_FEATURE_M)) {
+        return false;
+    }
+    if (IS_USER(s)) {
+        unallocated_encoding(s);
+        return true;
+    }
+
+    addr = load_reg(s, a->rn);
+    tcg_gen_addi_i32(tcg_ctx, addr, addr, pre_offset[a->pu]);
+
+    /* Load PC into tmp and CPSR into tmp2.  */
+    t1 = tcg_temp_new_i32(tcg_ctx);
+    gen_aa32_ld32u(s, t1, addr, get_mem_index(s));
+    tcg_gen_addi_i32(tcg_ctx, addr, addr, 4);
+    t2 = tcg_temp_new_i32(tcg_ctx);
+    gen_aa32_ld32u(s, t2, addr, get_mem_index(s));
+
+    if (a->w) {
+        /* Base writeback.  */
+        tcg_gen_addi_i32(tcg_ctx, addr, addr, post_offset[a->pu]);
+        store_reg(s, a->rn, addr);
+    } else {
+        tcg_temp_free_i32(tcg_ctx, addr);
+    }
+    gen_rfe(s, t1, t2);
+    return true;
+}
+
+static bool trans_SRS(DisasContext *s, arg_SRS *a)
+{
+    if (!ENABLE_ARCH_6 || arm_dc_feature(s, ARM_FEATURE_M)) {
+        return false;
+    }
+    gen_srs(s, a->mode, a->pu, a->w);
+    return true;
+}
+
 /*
  * Legacy decoder.
  */
@@ -10436,10 +10489,7 @@ static bool trans_SVC(DisasContext *s, arg_SVC *a)
 static void disas_arm_insn(DisasContext *s, unsigned int insn)
 {
     TCGContext *tcg_ctx = s->uc->tcg_ctx;
-    unsigned int cond, op1, i, rn;
+    unsigned int cond, op1;
-    TCGv_i32 tmp;
-    TCGv_i32 tmp2;
-    TCGv_i32 addr;
 
     /* M variants do not implement ARM mode; this must raise the INVSTATE
      * UsageFault exception.
@@ -10566,52 +10616,6 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
             default:
                 goto illegal_op;
             }
-        } else if ((insn & 0x0e5fffe0) == 0x084d0500) {
-            /* srs */
-            ARCH(6);
-            gen_srs(s, (insn & 0x1f), (insn >> 23) & 3, insn & (1 << 21));
-            return;
-        } else if ((insn & 0x0e50ffe0) == 0x08100a00) {
-            /* rfe */
-            int32_t offset;
-            if (IS_USER(s))
-                goto illegal_op;
-            ARCH(6);
-            rn = (insn >> 16) & 0xf;
-            addr = load_reg(s, rn);
-            i = (insn >> 23) & 3;
-            switch (i) {
-            case 0: offset = -4; break; /* DA */
-            case 1: offset = 0; break; /* IA */
-            case 2: offset = -8; break; /* DB */
-            case 3: offset = 4; break; /* IB */
-            default: abort();
-            }
-            if (offset)
-                tcg_gen_addi_i32(tcg_ctx, addr, addr, offset);
-            /* Load PC into tmp and CPSR into tmp2.  */
-            tmp = tcg_temp_new_i32(tcg_ctx);
-            gen_aa32_ld32u(s, tmp, addr, get_mem_index(s));
-            tcg_gen_addi_i32(tcg_ctx, addr, addr, 4);
-            tmp2 = tcg_temp_new_i32(tcg_ctx);
-            gen_aa32_ld32u(s, tmp2, addr, get_mem_index(s));
-            if (insn & (1 << 21)) {
-                /* Base writeback.  */
-                switch (i) {
-                case 0: offset = -8; break;
-                case 1: offset = 4; break;
-                case 2: offset = -4; break;
-                case 3: offset = 0; break;
-                default: abort();
-                }
-                if (offset)
-                    tcg_gen_addi_i32(tcg_ctx, addr, addr, offset);
-                store_reg(s, rn, addr);
-            } else {
-                tcg_temp_free_i32(tcg_ctx, addr);
-            }
-            gen_rfe(s, tmp, tmp2);
-            return;
         } else if ((insn & 0x0e000f00) == 0x0c000100) {
             if (arm_dc_feature(s, ARM_FEATURE_IWMMXT)) {
                 /* iWMMXt register transfer.  */
@@ -10777,7 +10781,6 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
     uint32_t imm, offset;
     uint32_t rd, rn, rm, rs;
     TCGv_i32 tmp;
-    TCGv_i32 tmp2;
     TCGv_i32 addr;
     int op;
 
@@ -10921,45 +10924,9 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
                 goto illegal_op;
             }
         } else {
-            /* Load/store multiple, RFE, SRS.  */
+            /* Load/store multiple, RFE, SRS, in decodetree */
-            if (((insn >> 23) & 1) == ((insn >> 24) & 1)) {
-                /* RFE, SRS: not available in user mode or on M profile */
-                if (IS_USER(s) || arm_dc_feature(s, ARM_FEATURE_M)) {
             goto illegal_op;
         }
-                if (insn & (1 << 20)) {
-                    /* rfe */
-                    addr = load_reg(s, rn);
-                    if ((insn & (1 << 24)) == 0)
-                        tcg_gen_addi_i32(tcg_ctx, addr, addr, -8);
-                    /* Load PC into tmp and CPSR into tmp2.  */
-                    tmp = tcg_temp_new_i32(tcg_ctx);
-                    gen_aa32_ld32u(s, tmp, addr, get_mem_index(s));
-                    tcg_gen_addi_i32(tcg_ctx, addr, addr, 4);
-                    tmp2 = tcg_temp_new_i32(tcg_ctx);
-                    gen_aa32_ld32u(s, tmp2, addr, get_mem_index(s));
-                    if (insn & (1 << 21)) {
-                        /* Base writeback.  */
-                        if (insn & (1 << 24)) {
-                            tcg_gen_addi_i32(tcg_ctx, addr, addr, 4);
-                        } else {
-                            tcg_gen_addi_i32(tcg_ctx, addr, addr, -4);
-                        }
-                        store_reg(s, rn, addr);
-                    } else {
-                        tcg_temp_free_i32(tcg_ctx, addr);
-                    }
-                    gen_rfe(s, tmp, tmp2);
-                } else {
-                    /* srs */
-                    gen_srs(s, (insn & 0x1f), (insn & (1 << 24)) ? 1 : 2,
-                            insn & (1 << 21));
-                }
-            } else {
-                /* Load/store multiple, in decodetree */
-                goto illegal_op;
-            }
-        }
         break;
     case 5:
         /* All in decodetree */