[Qemu-ppc] [PATCH 22/45] mmu-hash32: Split out handling of direct store segments

[David Gibson]

At present a large chunk of ppc_hash32_translate() is taken up with an
ugly if selecting between direct store segments (hardly ever used) and
normal paged segments.  This patch clarifies the flow of code by
handling direct store segments immediately then returning, leaving the
straight line code to describe the normal MMU path.

Signed-off-by: David Gibson <address@hidden>
---
 target-ppc/mmu-hash32.c |  156 +++++++++++++++++++++++------------------------
 1 file changed, 78 insertions(+), 78 deletions(-)

diff --git a/target-ppc/mmu-hash32.c b/target-ppc/mmu-hash32.c
index bc97834..04ddf1d 100644
--- a/target-ppc/mmu-hash32.c
+++ b/target-ppc/mmu-hash32.c
@@ -381,7 +381,7 @@ static int ppc_hash32_translate(CPUPPCState *env, struct 
mmu_ctx_hash32 *ctx,
 {
     hwaddr hash;
     target_ulong vsid;
-    int ds, pr, target_page_bits;
+    int pr, target_page_bits;
     int ret, ret2;
     target_ulong sr, pgidx;
 
@@ -401,91 +401,21 @@ static int ppc_hash32_translate(CPUPPCState *env, struct 
mmu_ctx_hash32 *ctx,
         }
     }
 
-    pr = msr_pr;
-
+    /* 3. Look up the Segment Register */
     sr = env->sr[eaddr >> 28];
+
+    pr = msr_pr;
     ctx->key = (((sr & SR32_KP) && (pr != 0)) ||
                 ((sr & SR32_KS) && (pr == 0))) ? 1 : 0;
-    ds = !!(sr & SR32_T);
-    ctx->nx = !!(sr & SR32_NX);
-    vsid = sr & SR32_VSID;
-    target_page_bits = TARGET_PAGE_BITS;
-    LOG_MMU("Check segment v=" TARGET_FMT_lx " %d " TARGET_FMT_lx " nip="
-            TARGET_FMT_lx " lr=" TARGET_FMT_lx
-            " ir=%d dr=%d pr=%d %d\n",
-            eaddr, (int)(eaddr >> 28), sr, env->nip, env->lr, (int)msr_ir,
-            (int)msr_dr, pr != 0 ? 1 : 0, rwx);
-    pgidx = (eaddr & ~SEGMENT_MASK_256M) >> target_page_bits;
-    hash = vsid ^ pgidx;
-    ctx->ptem = (vsid << 7) | (pgidx >> 10);
-
-    LOG_MMU("pte segment: key=%d ds %d nx %d vsid " TARGET_FMT_lx "\n",
-            ctx->key, ds, ctx->nx, vsid);
-    ret = -1;
-    if (!ds) {
-        /* Check if instruction fetch is allowed, if needed */
-        if (rwx != 2 || ctx->nx == 0) {
-            /* Page address translation */
-            LOG_MMU("htab_base " TARGET_FMT_plx " htab_mask " TARGET_FMT_plx
-                    " hash " TARGET_FMT_plx "\n",
-                    env->htab_base, env->htab_mask, hash);
-            ctx->hash[0] = hash;
-            ctx->hash[1] = ~hash;
-
-            /* Initialize real address with an invalid value */
-            ctx->raddr = (hwaddr)-1ULL;
-            LOG_MMU("0 htab=" TARGET_FMT_plx "/" TARGET_FMT_plx
-                    " vsid=" TARGET_FMT_lx " ptem=" TARGET_FMT_lx
-                    " hash=" TARGET_FMT_plx "\n",
-                    env->htab_base, env->htab_mask, vsid, ctx->ptem,
-                    ctx->hash[0]);
-            /* Primary table lookup */
-            ret = find_pte32(env, ctx, eaddr, 0, rwx, target_page_bits);
-            if (ret < 0) {
-                /* Secondary table lookup */
-                LOG_MMU("1 htab=" TARGET_FMT_plx "/" TARGET_FMT_plx
-                        " vsid=" TARGET_FMT_lx " api=" TARGET_FMT_lx
-                        " hash=" TARGET_FMT_plx "\n", env->htab_base,
-                        env->htab_mask, vsid, ctx->ptem, ctx->hash[1]);
-                ret2 = find_pte32(env, ctx, eaddr, 1, rwx, target_page_bits);
-                if (ret2 != -1) {
-                    ret = ret2;
-                }
-            }
-#if defined(DUMP_PAGE_TABLES)
-            if (qemu_log_enabled()) {
-                hwaddr curaddr;
-                uint32_t a0, a1, a2, a3;
-
-                qemu_log("Page table: " TARGET_FMT_plx " len " TARGET_FMT_plx
-                         "\n", sdr, mask + 0x80);
-                for (curaddr = sdr; curaddr < (sdr + mask + 0x80);
-                     curaddr += 16) {
-                    a0 = ldl_phys(curaddr);
-                    a1 = ldl_phys(curaddr + 4);
-                    a2 = ldl_phys(curaddr + 8);
-                    a3 = ldl_phys(curaddr + 12);
-                    if (a0 != 0 || a1 != 0 || a2 != 0 || a3 != 0) {
-                        qemu_log(TARGET_FMT_plx ": %08x %08x %08x %08x\n",
-                                 curaddr, a0, a1, a2, a3);
-                    }
-                }
-            }
-#endif
-        } else {
-            LOG_MMU("No access allowed\n");
-            ret = -3;
-        }
-    } else {
-        target_ulong sr;
 
+    /* 4. Handle direct store segments */
+    if (sr & SR32_T) {
         LOG_MMU("direct store...\n");
         /* Direct-store segment : absolutely *BUGGY* for now */
 
         /* Direct-store implies a 32-bit MMU.
          * Check the Segment Register's bus unit ID (BUID).
          */
-        sr = env->sr[eaddr >> 28];
         if ((sr & 0x1FF00000) >> 20 == 0x07f) {
             /* Memory-forced I/O controller interface access */
             /* If T=1 and BUID=x'07F', the 601 performs a memory access
@@ -528,10 +458,80 @@ static int ppc_hash32_translate(CPUPPCState *env, struct 
mmu_ctx_hash32 *ctx,
         }
         if ((rwx == 1 || ctx->key != 1) && (rwx == 0 || ctx->key != 0)) {
             ctx->raddr = eaddr;
-            ret = 2;
+            return 2;
         } else {
-            ret = -2;
+            return -2;
+        }
+    }
+
+    ctx->nx = !!(sr & SR32_NX);
+    vsid = sr & SR32_VSID;
+    target_page_bits = TARGET_PAGE_BITS;
+    LOG_MMU("Check segment v=" TARGET_FMT_lx " %d " TARGET_FMT_lx " nip="
+            TARGET_FMT_lx " lr=" TARGET_FMT_lx
+            " ir=%d dr=%d pr=%d %d\n",
+            eaddr, (int)(eaddr >> 28), sr, env->nip, env->lr, (int)msr_ir,
+            (int)msr_dr, pr != 0 ? 1 : 0, rwx);
+    pgidx = (eaddr & ~SEGMENT_MASK_256M) >> target_page_bits;
+    hash = vsid ^ pgidx;
+    ctx->ptem = (vsid << 7) | (pgidx >> 10);
+
+    LOG_MMU("pte segment: key=%d nx %d vsid " TARGET_FMT_lx "\n",
+            ctx->key, ctx->nx, vsid);
+    ret = -1;
+
+    /* Check if instruction fetch is allowed, if needed */
+    if (rwx != 2 || ctx->nx == 0) {
+        /* Page address translation */
+        LOG_MMU("htab_base " TARGET_FMT_plx " htab_mask " TARGET_FMT_plx
+                " hash " TARGET_FMT_plx "\n",
+                env->htab_base, env->htab_mask, hash);
+        ctx->hash[0] = hash;
+        ctx->hash[1] = ~hash;
+
+        /* Initialize real address with an invalid value */
+        ctx->raddr = (hwaddr)-1ULL;
+        LOG_MMU("0 htab=" TARGET_FMT_plx "/" TARGET_FMT_plx
+                " vsid=" TARGET_FMT_lx " ptem=" TARGET_FMT_lx
+                " hash=" TARGET_FMT_plx "\n",
+                env->htab_base, env->htab_mask, vsid, ctx->ptem,
+                ctx->hash[0]);
+        /* Primary table lookup */
+        ret = find_pte32(env, ctx, eaddr, 0, rwx, target_page_bits);
+        if (ret < 0) {
+            /* Secondary table lookup */
+            LOG_MMU("1 htab=" TARGET_FMT_plx "/" TARGET_FMT_plx
+                    " vsid=" TARGET_FMT_lx " api=" TARGET_FMT_lx
+                    " hash=" TARGET_FMT_plx "\n", env->htab_base,
+                    env->htab_mask, vsid, ctx->ptem, ctx->hash[1]);
+            ret2 = find_pte32(env, ctx, eaddr, 1, rwx, target_page_bits);
+            if (ret2 != -1) {
+                ret = ret2;
+            }
         }
+#if defined(DUMP_PAGE_TABLES)
+        if (qemu_log_enabled()) {
+            hwaddr curaddr;
+            uint32_t a0, a1, a2, a3;
+
+            qemu_log("Page table: " TARGET_FMT_plx " len " TARGET_FMT_plx
+                     "\n", sdr, mask + 0x80);
+            for (curaddr = sdr; curaddr < (sdr + mask + 0x80);
+                 curaddr += 16) {
+                a0 = ldl_phys(curaddr);
+                a1 = ldl_phys(curaddr + 4);
+                a2 = ldl_phys(curaddr + 8);
+                a3 = ldl_phys(curaddr + 12);
+                if (a0 != 0 || a1 != 0 || a2 != 0 || a3 != 0) {
+                    qemu_log(TARGET_FMT_plx ": %08x %08x %08x %08x\n",
+                             curaddr, a0, a1, a2, a3);
+                }
+            }
+        }
+#endif
+    } else {
+        LOG_MMU("No access allowed\n");
+        ret = -3;
     }
 
     return ret;
-- 
1.7.10.4