target-alpha: Cleanup MMU modes.

Don't bother including executive and supervisor modes.

Signed-off-by: Richard Henderson <rth@twiddle.net>

2 files changed, 32 insertions, 12 deletions

diff --git a/target-alpha/cpu.h b/target-alpha/cpu.h
index 0daa5563ec..6b9deb394c 100644
--- a/target-alpha/cpu.h
+++ b/target-alpha/cpu.h
@@ -317,9 +317,34 @@ enum {
     IPR_LAST,
 };
 
-typedef struct CPUAlphaState CPUAlphaState;
+/* MMU modes definitions */
+
+/* Alpha has 5 MMU modes: PALcode, kernel, executive, supervisor, and user.
+   The Unix PALcode only exposes the kernel and user modes; presumably
+   executive and supervisor are used by VMS.
+
+   PALcode itself uses physical mode for code and kernel mode for data;
+   there are PALmode instructions that can access data via physical mode
+   or via an os-installed "alternate mode", which is one of the 4 above.
+
+   QEMU does not currently properly distinguish between code/data when
+   looking up addresses.  To avoid having to address this issue, our
+   emulated PALcode will cheat and use the KSEG mapping for its code+data
+   rather than physical addresses.
+
+   Moreover, we're only emulating Unix PALcode, and not attempting VMS.
+
+   All of which allows us to drop all but kernel and user modes.
+   Elide the unused MMU modes to save space.  */
 
-#define NB_MMU_MODES 4
+#define NB_MMU_MODES 2
+
+#define MMU_MODE0_SUFFIX _kernel
+#define MMU_MODE1_SUFFIX _user
+#define MMU_KERNEL_IDX   0
+#define MMU_USER_IDX     1
+
+typedef struct CPUAlphaState CPUAlphaState;
 
 struct CPUAlphaState {
     uint64_t ir[31];
@@ -370,15 +395,9 @@ struct CPUAlphaState {
 #define cpu_gen_code cpu_alpha_gen_code
 #define cpu_signal_handler cpu_alpha_signal_handler
 
-/* MMU modes definitions */
-#define MMU_MODE0_SUFFIX _kernel
-#define MMU_MODE1_SUFFIX _executive
-#define MMU_MODE2_SUFFIX _supervisor
-#define MMU_MODE3_SUFFIX _user
-#define MMU_USER_IDX 3
 static inline int cpu_mmu_index (CPUState *env)
 {
-    return (env->ps >> 3) & 3;
+    return (env->ps >> 3) & 1;
 }
 
 #include "cpu-all.h"
diff --git a/target-alpha/translate.c b/target-alpha/translate.c
index 851a045681..2c0b9c2e6f 100644
--- a/target-alpha/translate.c
+++ b/target-alpha/translate.c
@@ -1522,8 +1522,9 @@ static ExitStatus translate_one(DisasContext *ctx, uint32_t insn)
 #ifndef CONFIG_USER_ONLY
         if (palcode < 0x40) {
             /* Privileged PAL code */
-            if (ctx->mem_idx & 1)
+            if (ctx->mem_idx != MMU_KERNEL_IDX) {
                 goto invalid_opc;
+            }
             ret = gen_excp(ctx, EXCP_CALL_PALP + ((palcode & 0x3F) << 6), 0);
         }
 #endif
@@ -2651,11 +2652,11 @@ static ExitStatus translate_one(DisasContext *ctx, uint32_t insn)
                 goto invalid_opc;
             case 0xA:
                 /* Longword virtual access with protection check (hw_ldl/w) */
-                tcg_gen_qemu_ld32s(cpu_ir[ra], addr, 0);
+                tcg_gen_qemu_ld32s(cpu_ir[ra], addr, MMU_KERNEL_IDX);
                 break;
             case 0xB:
                 /* Quadword virtual access with protection check (hw_ldq/w) */
-                tcg_gen_qemu_ld64(cpu_ir[ra], addr, 0);
+                tcg_gen_qemu_ld64(cpu_ir[ra], addr, MMU_KERNEL_IDX);
                 break;
             case 0xC:
                 /* Longword virtual access with alt access mode (hw_ldl/a)*/