target/riscv: Remove the hardcoded SSTATUS_SD macro

This also ensures that the SD bit is not writable.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-id: 9ea842309f0fd7adff172790f5b5fc058b40f2f1.1619234854.git.alistair.francis@wdc.com

target/riscv/cpu_bits.h

@@ -403,12 +403,6 @@
 #define SSTATUS32_SD        0x80000000
 #define SSTATUS64_SD        0x8000000000000000ULL
 
-#if defined(TARGET_RISCV32)
-#define SSTATUS_SD SSTATUS32_SD
-#elif defined(TARGET_RISCV64)
-#define SSTATUS_SD SSTATUS64_SD
-#endif
-
 /* hstatus CSR bits */
 #define HSTATUS_VSBE         0x00000020
 #define HSTATUS_GVA          0x00000040

target/riscv/csr.c

@@ -459,7 +459,7 @@ static const target_ulong delegable_excps =
     (1ULL << (RISCV_EXCP_STORE_GUEST_AMO_ACCESS_FAULT));
 static const target_ulong sstatus_v1_10_mask = SSTATUS_SIE | SSTATUS_SPIE |
     SSTATUS_UIE | SSTATUS_UPIE | SSTATUS_SPP | SSTATUS_FS | SSTATUS_XS |
-    SSTATUS_SUM | SSTATUS_MXR | SSTATUS_SD;
+    SSTATUS_SUM | SSTATUS_MXR;
 static const target_ulong sip_writable_mask = SIP_SSIP | MIP_USIP | MIP_UEIP;
 static const target_ulong hip_writable_mask = MIP_VSSIP;
 static const target_ulong hvip_writable_mask = MIP_VSSIP | MIP_VSTIP | MIP_VSEIP;
@@ -788,6 +788,13 @@ static RISCVException read_sstatus(CPURISCVState *env, int csrno,
                                    target_ulong *val)
 {
     target_ulong mask = (sstatus_v1_10_mask);
+
+    if (riscv_cpu_is_32bit(env)) {
+        mask |= SSTATUS32_SD;
+    } else {
+        mask |= SSTATUS64_SD;
+    }
+
     *val = env->mstatus & mask;
     return RISCV_EXCP_NONE;
 }