target/riscv: Reorg csr instructions

Introduce csrr and csrw helpers, for read-only and write-only insns.

Note that we do not properly implement this in riscv_csrrw, in that
we cannot distinguish true read-only (rs1 == 0) from any other zero
write_mask another source register -- this should still raise an
exception for read-only registers.

Only issue gen_io_start for CF_USE_ICOUNT.
Use ctx->zero for csrrc.
Use get_gpr and dest_gpr.

Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210823195529.560295-19-richard.henderson@linaro.org
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 7 insertions, 11 deletions

diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index 3c48e739ac..ee7c24efe7 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -37,11 +37,10 @@ void helper_raise_exception(CPURISCVState *env, uint32_t exception)
     riscv_raise_exception(env, exception, 0);
 }
 
-target_ulong helper_csrrw(CPURISCVState *env, target_ulong src,
-        target_ulong csr)
+target_ulong helper_csrr(CPURISCVState *env, int csr)
 {
     target_ulong val = 0;
-    RISCVException ret = riscv_csrrw(env, csr, &val, src, -1);
+    RISCVException ret = riscv_csrrw(env, csr, &val, 0, 0);
 
     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
@@ -49,23 +48,20 @@ target_ulong helper_csrrw(CPURISCVState *env, target_ulong src,
     return val;
 }
 
-target_ulong helper_csrrs(CPURISCVState *env, target_ulong src,
-        target_ulong csr, target_ulong rs1_pass)
+void helper_csrw(CPURISCVState *env, int csr, target_ulong src)
 {
-    target_ulong val = 0;
-    RISCVException ret = riscv_csrrw(env, csr, &val, -1, rs1_pass ? src : 0);
+    RISCVException ret = riscv_csrrw(env, csr, NULL, src, -1);
 
     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }
-    return val;
 }
 
-target_ulong helper_csrrc(CPURISCVState *env, target_ulong src,
-        target_ulong csr, target_ulong rs1_pass)
+target_ulong helper_csrrw(CPURISCVState *env, int csr,
+                          target_ulong src, target_ulong write_mask)
 {
     target_ulong val = 0;
-    RISCVException ret = riscv_csrrw(env, csr, &val, 0, rs1_pass ? src : 0);
+    RISCVException ret = riscv_csrrw(env, csr, &val, src, write_mask);
 
     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());