[Qemu-devel] [PATCH 11/21] target-mips: Status.UX/SX/KX enable 32-bit address wrapping

[Leon Alrae]

In R6 the special behaviour for data references is also specified for Kernel
and Supervisor mode. Therefore MIPS_HFLAG_UX is replaced by generic MIPS_HFLAG_X
indicating whether 64-bit mode is enabled in current operating mode.

Signed-off-by: Leon Alrae <address@hidden>
---
 target-mips/cpu.h       |   14 ++++++++++----
 target-mips/translate.c |   20 +++++++++++++++-----
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/target-mips/cpu.h b/target-mips/cpu.h
index 6c2014e..3dbc219 100644
--- a/target-mips/cpu.h
+++ b/target-mips/cpu.h
@@ -447,7 +447,7 @@ struct CPUMIPSState {
        and RSQRT.D.  */
 #define MIPS_HFLAG_COP1X  0x00080 /* COP1X instructions enabled         */
 #define MIPS_HFLAG_RE     0x00100 /* Reversed endianness                */
-#define MIPS_HFLAG_UX     0x00200 /* 64-bit user mode                   */
+#define MIPS_HFLAG_X      0x00200 /* 64-bit mode enabled                */
 #define MIPS_HFLAG_M16    0x00400 /* MIPS16 mode flag                   */
 #define MIPS_HFLAG_M16_SHIFT 10
     /* If translation is interrupted between the branch instruction and
@@ -721,7 +721,7 @@ static inline void compute_hflags(CPUMIPSState *env)
 {
     env->hflags &= ~(MIPS_HFLAG_COP1X | MIPS_HFLAG_64 | MIPS_HFLAG_CP0 |
                      MIPS_HFLAG_F64 | MIPS_HFLAG_FPU | MIPS_HFLAG_KSU |
-                     MIPS_HFLAG_UX | MIPS_HFLAG_DSP | MIPS_HFLAG_DSPR2);
+                     MIPS_HFLAG_X | MIPS_HFLAG_DSP | MIPS_HFLAG_DSPR2);
     if (!(env->CP0_Status & (1 << CP0St_EXL)) &&
         !(env->CP0_Status & (1 << CP0St_ERL)) &&
         !(env->hflags & MIPS_HFLAG_DM)) {
@@ -733,8 +733,14 @@ static inline void compute_hflags(CPUMIPSState *env)
         (env->CP0_Status & (1 << CP0St_UX))) {
         env->hflags |= MIPS_HFLAG_64;
     }
-    if (env->CP0_Status & (1 << CP0St_UX)) {
-        env->hflags |= MIPS_HFLAG_UX;
+
+    if ((((env->hflags & MIPS_HFLAG_KSU) == MIPS_HFLAG_UM) &&
+         (env->CP0_Status & (1 << CP0St_UX))) ||
+        (((env->hflags & MIPS_HFLAG_KSU) == MIPS_HFLAG_SM) &&
+         (env->CP0_Status & (1 << CP0St_SX))) ||
+        (((env->hflags & MIPS_HFLAG_KSU) == MIPS_HFLAG_KM) &&
+         (env->CP0_Status & (1 << CP0St_KX)))) {
+        env->hflags |= MIPS_HFLAG_X;
     }
 #endif
     if ((env->CP0_Status & (1 << CP0St_CU0)) ||
diff --git a/target-mips/translate.c b/target-mips/translate.c
index 2e94375..6d294e1 100644
--- a/target-mips/translate.c
+++ b/target-mips/translate.c
@@ -1373,17 +1373,27 @@ generate_exception (DisasContext *ctx, int excp)
     gen_helper_0e0i(raise_exception, excp);
 }
 
+#if defined(TARGET_MIPS64)
+static inline int is_wrapping_needed(DisasContext *ctx)
+{
+    if (!(ctx->hflags & MIPS_HFLAG_X)) {
+        /* If not R6 then wrap only in User Mode */
+        if ((ctx->insn_flags & ISA_MIPS64R6) ||
+            ((ctx->hflags & MIPS_HFLAG_KSU) == MIPS_HFLAG_UM)) {
+            return 1;
+        }
+    }
+    return 0;
+}
+#endif
+
 /* Addresses computation */
 static inline void gen_op_addr_add (DisasContext *ctx, TCGv ret, TCGv arg0, 
TCGv arg1)
 {
     tcg_gen_add_tl(ret, arg0, arg1);
 
 #if defined(TARGET_MIPS64)
-    /* For compatibility with 32-bit code, data reference in user mode
-       with Status_UX = 0 should be casted to 32-bit and sign extended.
-       See the MIPS64 PRA manual, section 4.10. */
-    if (((ctx->hflags & MIPS_HFLAG_KSU) == MIPS_HFLAG_UM) &&
-        !(ctx->hflags & MIPS_HFLAG_UX)) {
+    if (is_wrapping_needed(ctx)) {
         tcg_gen_ext32s_i64(ret, ret);
     }
 #endif
-- 
1.7.5.4