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, 16 insertions, 12 deletions

diff --git a/target-sparc/ldst_helper.c b/target-sparc/ldst_helper.c
index 92761ad17b..32491b499a 100644
--- a/target-sparc/ldst_helper.c
+++ b/target-sparc/ldst_helper.c
@@ -584,6 +584,7 @@ uint64_t helper_ld_asi(CPUSPARCState *env, target_ulong addr, int asi, int size,
         }
         break;
     case 0xb: /* Supervisor data access */
+    case 0x80:
         switch (size) {
         case 1:
             ret = cpu_ldub_kernel(env, addr);
@@ -955,6 +956,7 @@ void helper_st_asi(CPUSPARCState *env, target_ulong addr, uint64_t val, int asi,
         }
         break;
     case 0xb: /* Supervisor data access */
+    case 0x80:
         switch (size) {
         case 1:
             cpu_stb_kernel(env, addr, val);
@@ -2232,33 +2234,35 @@ void helper_stf_asi(CPUSPARCState *env, target_ulong addr, int asi, int size,
     }
 }
 
-target_ulong helper_cas_asi(CPUSPARCState *env, target_ulong addr,
-                            target_ulong val1, target_ulong val2, uint32_t asi)
+target_ulong helper_casx_asi(CPUSPARCState *env, target_ulong addr,
+                             target_ulong val1, target_ulong val2,
+                             uint32_t asi)
 {
     target_ulong ret;
 
-    val2 &= 0xffffffffUL;
-    ret = helper_ld_asi(env, addr, asi, 4, 0);
-    ret &= 0xffffffffUL;
+    ret = helper_ld_asi(env, addr, asi, 8, 0);
     if (val2 == ret) {
-        helper_st_asi(env, addr, val1 & 0xffffffffUL, asi, 4);
+        helper_st_asi(env, addr, val1, asi, 8);
     }
     return ret;
 }
+#endif /* TARGET_SPARC64 */
 
-target_ulong helper_casx_asi(CPUSPARCState *env, target_ulong addr,
-                             target_ulong val1, target_ulong val2,
-                             uint32_t asi)
+#if !defined(CONFIG_USER_ONLY) || defined(TARGET_SPARC64)
+target_ulong helper_cas_asi(CPUSPARCState *env, target_ulong addr,
+                            target_ulong val1, target_ulong val2, uint32_t asi)
 {
     target_ulong ret;
 
-    ret = helper_ld_asi(env, addr, asi, 8, 0);
+    val2 &= 0xffffffffUL;
+    ret = helper_ld_asi(env, addr, asi, 4, 0);
+    ret &= 0xffffffffUL;
     if (val2 == ret) {
-        helper_st_asi(env, addr, val1, asi, 8);
+        helper_st_asi(env, addr, val1 & 0xffffffffUL, asi, 4);
     }
     return ret;
 }
-#endif /* TARGET_SPARC64 */
+#endif /* !defined(CONFIG_USER_ONLY) || defined(TARGET_SPARC64) */
 
 void helper_ldqf(CPUSPARCState *env, target_ulong addr, int mem_idx)
 {