target-sparc: Add and use CPU_FEATURE_CASA

The LEON3 processor has support for the CASA instruction which is
normally only available for SPARC V9 processors.  Binutils 2.24
and GCC 4.9 will support this instruction for LEON3.  GCC uses it to
generate C11 atomic operations.

The CAS synthetic instruction uses an ASI of 0x80.  If TARGET_SPARC64 is
not defined use a supervisor data load/store for an ASI of 0x80 in
helper_ld_asi()/helper_st_asi().  The supervisor data load/store was
choosen according to the LEON3 documentation.

The ASI 0x80 is defined in the SPARC V9 manual, Table 12—Address Space
Identifiers (ASIs).  Here we have: 0x80, ASI_PRIMARY, Unrestricted
access, Primary address space.

Tested with the following program:

  #include <assert.h>
  #include <stdatomic.h>

  void test(void)
  {
    atomic_int a;
    int e;
    _Bool b;

    atomic_store(&a, 1);
    e = 1;
    b = atomic_compare_exchange_strong(&a, &e, 2);
    assert(b);
    assert(atomic_load(&a) == 2);

    atomic_store(&a, 3);
    e = 4;
    b = atomic_compare_exchange_strong(&a, &e, 5);
    assert(!b);
    assert(atomic_load(&a) == 3);
  }

Tested also on a NGMP board with a LEON4 processor.

Reviewed-by: Fabien Chouteau <chouteau@adacore.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

1 files changed, 32 insertions, 17 deletions

diff --git a/target-sparc/translate.c b/target-sparc/translate.c
index 6150b22f8f..46d7859e97 100644
--- a/target-sparc/translate.c
+++ b/target-sparc/translate.c
@@ -2107,18 +2107,6 @@ static inline void gen_stda_asi(DisasContext *dc, TCGv hi, TCGv addr,
     tcg_temp_free_i64(t64);
 }
 
-static inline void gen_cas_asi(DisasContext *dc, TCGv addr,
-                               TCGv val2, int insn, int rd)
-{
-    TCGv val1 = gen_load_gpr(dc, rd);
-    TCGv dst = gen_dest_gpr(dc, rd);
-    TCGv_i32 r_asi = gen_get_asi(insn, addr);
-
-    gen_helper_cas_asi(dst, cpu_env, addr, val1, val2, r_asi);
-    tcg_temp_free_i32(r_asi);
-    gen_store_gpr(dc, rd, dst);
-}
-
 static inline void gen_casx_asi(DisasContext *dc, TCGv addr,
                                 TCGv val2, int insn, int rd)
 {
@@ -2229,6 +2217,22 @@ static inline void gen_stda_asi(DisasContext *dc, TCGv hi, TCGv addr,
 #endif
 
 #if !defined(CONFIG_USER_ONLY) || defined(TARGET_SPARC64)
+static inline void gen_cas_asi(DisasContext *dc, TCGv addr,
+                               TCGv val2, int insn, int rd)
+{
+    TCGv val1 = gen_load_gpr(dc, rd);
+    TCGv dst = gen_dest_gpr(dc, rd);
+#ifdef TARGET_SPARC64
+    TCGv_i32 r_asi = gen_get_asi(insn, addr);
+#else
+    TCGv_i32 r_asi = tcg_const_i32(GET_FIELD(insn, 19, 26));
+#endif
+
+    gen_helper_cas_asi(dst, cpu_env, addr, val1, val2, r_asi);
+    tcg_temp_free_i32(r_asi);
+    gen_store_gpr(dc, rd, dst);
+}
+
 static inline void gen_ldstub_asi(TCGv dst, TCGv addr, int insn)
 {
     TCGv_i64 r_val;
@@ -5103,11 +5107,6 @@ static void disas_sparc_insn(DisasContext * dc, unsigned int insn)
                     }
                     gen_stf_asi(cpu_addr, insn, 8, DFPREG(rd));
                     break;
-                case 0x3c: /* V9 casa */
-                    rs2 = GET_FIELD(insn, 27, 31);
-                    cpu_src2 = gen_load_gpr(dc, rs2);
-                    gen_cas_asi(dc, cpu_addr, cpu_src2, insn, rd);
-                    break;
                 case 0x3e: /* V9 casxa */
                     rs2 = GET_FIELD(insn, 27, 31);
                     cpu_src2 = gen_load_gpr(dc, rs2);
@@ -5120,6 +5119,22 @@ static void disas_sparc_insn(DisasContext * dc, unsigned int insn)
                 case 0x37: /* stdc */
                     goto ncp_insn;
 #endif
+#if !defined(CONFIG_USER_ONLY) || defined(TARGET_SPARC64)
+                case 0x3c: /* V9 or LEON3 casa */
+#ifndef TARGET_SPARC64
+                    CHECK_IU_FEATURE(dc, CASA);
+                    if (IS_IMM) {
+                        goto illegal_insn;
+                    }
+                    if (!supervisor(dc)) {
+                        goto priv_insn;
+                    }
+#endif
+                    rs2 = GET_FIELD(insn, 27, 31);
+                    cpu_src2 = gen_load_gpr(dc, rs2);
+                    gen_cas_asi(dc, cpu_addr, cpu_src2, insn, rd);
+                    break;
+#endif
                 default:
                     goto illegal_insn;
                 }