SH: Improve movca.l/ocbi emulation.

Author: Vladimir Prus <vladimir@codesourcery.com>

    Fix movcal.l/ocbi emulation.

        * target-sh4/cpu.h (memory_content): New.
        (CPUSH4State): New fields movcal_backup and movcal_backup_tail.
        * target-sh4/helper.h (helper_movcal)
        (helper_discard_movcal_backup, helper_ocbi): New.
        * target-sh4/op_helper.c (helper_movcal)
        (helper_discard_movcal_backup, helper_ocbi): New.
        * target-sh4/translate.c (DisasContext): New field has_movcal.
        (sh4_defs): Update CVS for SH7785.
        (cpu_sh4_init): Initialize env->movcal_backup_tail.
        (_decode_opc): Discard movca.l-backup.
        Make use of helper_movcal and helper_ocbi.
        (gen_intermediate_code_internal): Initialize has_movcal to 1.

Thanks to Shin-ichiro KAWASAKI and Paul Mundt for valuable feedback.

Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6966 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 42 insertions, 4 deletions

diff --git a/target-sh4/translate.c b/target-sh4/translate.c
index cc9f886..4ced176 100644
--- a/target-sh4/translate.c
+++ b/target-sh4/translate.c
@@ -50,6 +50,7 @@ typedef struct DisasContext {
     uint32_t delayed_pc;
     int singlestep_enabled;
     uint32_t features;
+    int has_movcal;
 } DisasContext;
 
 #if defined(CONFIG_USER_ONLY)
@@ -283,6 +284,7 @@ CPUSH4State *cpu_sh4_init(const char *cpu_model)
     env = qemu_mallocz(sizeof(CPUSH4State));
     env->features = def->features;
     cpu_exec_init(env);
+    env->movcal_backup_tail = &(env->movcal_backup);
     sh4_translate_init();
     env->cpu_model_str = cpu_model;
     cpu_sh4_reset(env);
@@ -495,6 +497,37 @@ static inline void gen_store_fpr64 (TCGv_i64 t, int reg)
 
 static void _decode_opc(DisasContext * ctx)
 {
+    /* This code tries to make movcal emulation sufficiently
+       accurate for Linux purposes.  This instruction writes
+       memory, and prior to that, always allocates a cache line.
+       It is used in two contexts:
+       - in memcpy, where data is copied in blocks, the first write
+       of to a block uses movca.l for performance.
+       - in arch/sh/mm/cache-sh4.c, movcal.l + ocbi combination is used
+       to flush the cache. Here, the data written by movcal.l is never
+       written to memory, and the data written is just bogus.
+
+       To simulate this, we simulate movcal.l, we store the value to memory,
+       but we also remember the previous content. If we see ocbi, we check
+       if movcal.l for that address was done previously. If so, the write should
+       not have hit the memory, so we restore the previous content.
+       When we see an instruction that is neither movca.l
+       nor ocbi, the previous content is discarded.
+
+       To optimize, we only try to flush stores when we're at the start of
+       TB, or if we already saw movca.l in this TB and did not flush stores
+       yet.  */
+    if (ctx->has_movcal)
+	{
+	  int opcode = ctx->opcode & 0xf0ff;
+	  if (opcode != 0x0093 /* ocbi */
+	      && opcode != 0x00c3 /* movca.l */)
+	      {
+		  gen_helper_discard_movcal_backup ();
+		  ctx->has_movcal = 0;
+	      }
+	}
+
 #if 0
     fprintf(stderr, "Translating opcode 0x%04x\n", ctx->opcode);
 #endif
@@ -1545,7 +1578,13 @@ static void _decode_opc(DisasContext * ctx)
 	}
 	return;
     case 0x00c3:		/* movca.l R0,@Rm */
-	tcg_gen_qemu_st32(REG(0), REG(B11_8), ctx->memidx);
+        {
+            TCGv val = tcg_temp_new();
+            tcg_gen_qemu_ld32u(val, REG(B11_8), ctx->memidx);
+            gen_helper_movcal (REG(B11_8), val);            
+            tcg_gen_qemu_st32(REG(0), REG(B11_8), ctx->memidx);
+        }
+        ctx->has_movcal = 1;
 	return;
     case 0x40a9:
 	/* MOVUA.L @Rm,R0 (Rm) -> R0
@@ -1594,9 +1633,7 @@ static void _decode_opc(DisasContext * ctx)
 	    break;
     case 0x0093:		/* ocbi @Rn */
 	{
-	    TCGv dummy = tcg_temp_new();
-	    tcg_gen_qemu_ld32s(dummy, REG(B11_8), ctx->memidx);
-	    tcg_temp_free(dummy);
+	    gen_helper_ocbi (REG(B11_8));
 	}
 	return;
     case 0x00a3:		/* ocbp @Rn */
@@ -1876,6 +1913,7 @@ gen_intermediate_code_internal(CPUState * env, TranslationBlock * tb,
     ctx.tb = tb;
     ctx.singlestep_enabled = env->singlestep_enabled;
     ctx.features = env->features;
+    ctx.has_movcal = (tb->flags & TB_FLAG_PENDING_MOVCA);
 
 #ifdef DEBUG_DISAS
     qemu_log_mask(CPU_LOG_TB_CPU,