target/arm: Implement the ADDG, SUBG instructions

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/helper-a64.h

@@ -105,3 +105,4 @@ DEF_HELPER_FLAGS_2(xpaci, TCG_CALL_NO_RWG_SE, i64, env, i64)
 DEF_HELPER_FLAGS_2(xpacd, TCG_CALL_NO_RWG_SE, i64, env, i64)
 
 DEF_HELPER_FLAGS_3(irg, TCG_CALL_NO_RWG, i64, env, i64, i64)
+DEF_HELPER_FLAGS_4(addsubg, TCG_CALL_NO_RWG_SE, i64, env, i64, s32, i32)

target/arm/internals.h

@@ -1261,6 +1261,15 @@ void arm_log_exception(int idx);
  */
 #define GMID_EL1_BS  6
 
+/* We associate one allocation tag per 16 bytes, the minimum.  */
+#define LOG2_TAG_GRANULE 4
+#define TAG_GRANULE      (1 << LOG2_TAG_GRANULE)
+
+static inline int allocation_tag_from_addr(uint64_t ptr)
+{
+    return extract64(ptr, 56, 4);
+}
+
 static inline uint64_t address_with_allocation_tag(uint64_t ptr, int rtag)
 {
     return deposit64(ptr, 56, 4, rtag);

target/arm/mte_helper.c

@@ -70,3 +70,13 @@ uint64_t HELPER(irg)(CPUARMState *env, uint64_t rn, uint64_t rm)
 
     return address_with_allocation_tag(rn, rtag);
 }
+
+uint64_t HELPER(addsubg)(CPUARMState *env, uint64_t ptr,
+                         int32_t offset, uint32_t tag_offset)
+{
+    int start_tag = allocation_tag_from_addr(ptr);
+    uint16_t exclude = extract32(env->cp15.gcr_el1, 0, 16);
+    int rtag = choose_nonexcluded_tag(start_tag, tag_offset, exclude);
+
+    return address_with_allocation_tag(ptr + offset, rtag);
+}

target/arm/translate-a64.c

@@ -3808,6 +3808,54 @@ static void disas_add_sub_imm(DisasContext *s, uint32_t insn)
     tcg_temp_free_i64(tcg_result);
 }
 
+/*
+ * Add/subtract (immediate, with tags)
+ *
+ *  31 30 29 28         23 22 21     16 14      10 9   5 4   0
+ * +--+--+--+-------------+--+---------+--+-------+-----+-----+
+ * |sf|op| S| 1 0 0 0 1 1 |o2|  uimm6  |o3| uimm4 |  Rn | Rd  |
+ * +--+--+--+-------------+--+---------+--+-------+-----+-----+
+ *
+ *    op: 0 -> add, 1 -> sub
+ */
+static void disas_add_sub_imm_with_tags(DisasContext *s, uint32_t insn)
+{
+    int rd = extract32(insn, 0, 5);
+    int rn = extract32(insn, 5, 5);
+    int uimm4 = extract32(insn, 10, 4);
+    int uimm6 = extract32(insn, 16, 6);
+    bool sub_op = extract32(insn, 30, 1);
+    TCGv_i64 tcg_rn, tcg_rd;
+    int imm;
+
+    /* Test all of sf=1, S=0, o2=0, o3=0.  */
+    if ((insn & 0xa040c000u) != 0x80000000u ||
+        !dc_isar_feature(aa64_mte_insn_reg, s)) {
+        unallocated_encoding(s);
+        return;
+    }
+
+    imm = uimm6 << LOG2_TAG_GRANULE;
+    if (sub_op) {
+        imm = -imm;
+    }
+
+    tcg_rn = cpu_reg_sp(s, rn);
+    tcg_rd = cpu_reg_sp(s, rd);
+
+    if (s->ata) {
+        TCGv_i32 offset = tcg_const_i32(imm);
+        TCGv_i32 tag_offset = tcg_const_i32(uimm4);
+
+        gen_helper_addsubg(tcg_rd, cpu_env, tcg_rn, offset, tag_offset);
+        tcg_temp_free_i32(tag_offset);
+        tcg_temp_free_i32(offset);
+    } else {
+        tcg_gen_addi_i64(tcg_rd, tcg_rn, imm);
+        gen_address_with_allocation_tag0(tcg_rd, tcg_rd);
+    }
+}
+
 /* The input should be a value in the bottom e bits (with higher
  * bits zero); returns that value replicated into every element
  * of size e in a 64 bit integer.
@@ -4170,6 +4218,9 @@ static void disas_data_proc_imm(DisasContext *s, uint32_t insn)
     case 0x22: /* Add/subtract (immediate) */
         disas_add_sub_imm(s, insn);
         break;
+    case 0x23: /* Add/subtract (immediate, with tags) */
+        disas_add_sub_imm_with_tags(s, insn);
+        break;
     case 0x24: /* Logical (immediate) */
         disas_logic_imm(s, insn);
         break;