[Qemu-devel] [PATCH 02/28] Clean up PowerPC SLB handling code

[qemu@gibson.dropbear.id.au]

From: David Gibson <david@gibson.dropbear.id.au>

Currently the SLB information when emulating a PowerPC 970 is
storeed in a structure with the unhelpfully named fields 'tmp'
and 'tmp64'.  While the layout in these fields does match the
description of the SLB in the architecture document, it is not
convenient either for looking up the SLB, or for emulating the
slbmte instruction.

This patch, therefore, reorganizes the SLB entry structure to be
divided in the the "ESID related" and "VSID related" fields as
they are divided in instructions accessing the SLB.

In addition to making the code smaller and more readable, this will
make it easier to implement for the 1TB segments used in more
recent PowerPC chips.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
---
 target-ppc/cpu.h       |   29 +++++++-
 target-ppc/helper.c    |  178 ++++++++++++++----------------------------------
 target-ppc/helper.h    |    1 -
 target-ppc/op_helper.c |    9 +--
 4 files changed, 80 insertions(+), 137 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index deb8d7c..a20c132 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -43,6 +43,8 @@
 # define TARGET_VIRT_ADDR_SPACE_BITS 64
 #endif
 
+#define TARGET_PAGE_BITS_16M 24
+
 #else /* defined (TARGET_PPC64) */
 /* PowerPC 32 definitions */
 #define TARGET_LONG_BITS 32
@@ -359,10 +361,31 @@ union ppc_tlb_t {
 
 typedef struct ppc_slb_t ppc_slb_t;
 struct ppc_slb_t {
-    uint64_t tmp64;
-    uint32_t tmp;
+    uint64_t esid;
+    uint64_t vsid;
 };
 
+/* Bits in the SLB ESID word */
+#define SLB_ESID_ESID           0xFFFFFFFFF0000000ULL
+#define SLB_ESID_V              0x0000000008000000ULL /* valid */
+
+/* Bits in the SLB VSID word */
+#define SLB_VSID_SHIFT          12
+#define SLB_VSID_SSIZE_SHIFT    62
+#define SLB_VSID_B              0xc000000000000000ULL
+#define SLB_VSID_B_256M         0x0000000000000000ULL
+#define SLB_VSID_VSID           0x3FFFFFFFFFFFF000ULL
+#define SLB_VSID_KS             0x0000000000000800ULL
+#define SLB_VSID_KP             0x0000000000000400ULL
+#define SLB_VSID_N              0x0000000000000200ULL /* no-execute */
+#define SLB_VSID_L              0x0000000000000100ULL
+#define SLB_VSID_C              0x0000000000000080ULL /* class */
+#define SLB_VSID_LP             0x0000000000000030ULL
+#define SLB_VSID_ATTR           0x0000000000000FFFULL
+
+#define SEGMENT_SHIFT_256M      28
+#define SEGMENT_MASK_256M       ~((1ULL << SEGMENT_SHIFT_256M) - 1)
+
 /*****************************************************************************/
 /* Machine state register bits definition                                    */
 #define MSR_SF   63 /* Sixty-four-bit mode                            hflags */
@@ -755,7 +778,7 @@ void ppc_store_sdr1 (CPUPPCState *env, target_ulong value);
 void ppc_store_asr (CPUPPCState *env, target_ulong value);
 target_ulong ppc_load_slb (CPUPPCState *env, int slb_nr);
 target_ulong ppc_load_sr (CPUPPCState *env, int sr_nr);
-void ppc_store_slb (CPUPPCState *env, target_ulong rb, target_ulong rs);
+int ppc_store_slb (CPUPPCState *env, target_ulong rb, target_ulong rs);
 #endif /* defined(TARGET_PPC64) */
 void ppc_store_sr (CPUPPCState *env, int srnum, target_ulong value);
 #endif /* !defined(CONFIG_USER_ONLY) */
diff --git a/target-ppc/helper.c b/target-ppc/helper.c
index 4b49101..2094ca3 100644
--- a/target-ppc/helper.c
+++ b/target-ppc/helper.c
@@ -672,85 +672,36 @@ static inline int find_pte(CPUState *env, mmu_ctx_t *ctx, int h, int rw,
 }
 
 #if defined(TARGET_PPC64)
-static ppc_slb_t *slb_get_entry(CPUPPCState *env, int nr)
-{
-    ppc_slb_t *retval = &env->slb[nr];
-
-#if 0 // XXX implement bridge mode?
-    if (env->spr[SPR_ASR] & 1) {
-        target_phys_addr_t sr_base;
-
-        sr_base = env->spr[SPR_ASR] & 0xfffffffffffff000;
-        sr_base += (12 * nr);
-
-        retval->tmp64 = ldq_phys(sr_base);
-        retval->tmp = ldl_phys(sr_base + 8);
-    }
-#endif
-
-    return retval;
-}
-
-static void slb_set_entry(CPUPPCState *env, int nr, ppc_slb_t *slb)
-{
-    ppc_slb_t *entry = &env->slb[nr];
-
-    if (slb == entry)
-        return;
-
-    entry->tmp64 = slb->tmp64;
-    entry->tmp = slb->tmp;
-}
-
-static inline int slb_is_valid(ppc_slb_t *slb)
-{
-    return (int)(slb->tmp64 & 0x0000000008000000ULL);
-}
-
-static inline void slb_invalidate(ppc_slb_t *slb)
-{
-    slb->tmp64 &= ~0x0000000008000000ULL;
-}
-
 static inline int slb_lookup(CPUPPCState *env, target_ulong eaddr,
                              target_ulong *vsid, target_ulong *page_mask,
                              int *attr, int *target_page_bits)
 {
-    target_ulong mask;
-    int n, ret;
+    uint64_t esid;
+    int n;
 
-    ret = -5;
     LOG_SLB("%s: eaddr " TARGET_FMT_lx "\n", __func__, eaddr);
-    mask = 0x0000000000000000ULL; /* Avoid gcc warning */
+
+    esid = (eaddr & SEGMENT_MASK_256M) | SLB_ESID_V;
+
     for (n = 0; n < env->slb_nr; n++) {
-        ppc_slb_t *slb = slb_get_entry(env, n);
-
-        LOG_SLB("%s: seg %d %016" PRIx64 " %08"
-                    PRIx32 "\n", __func__, n, slb->tmp64, slb->tmp);
-        if (slb_is_valid(slb)) {
-            /* SLB entry is valid */
-            mask = 0xFFFFFFFFF0000000ULL;
-            if (slb->tmp & 0x8) {
-                /* 16 MB PTEs */
-                if (target_page_bits)
-                    *target_page_bits = 24;
-            } else {
-                /* 4 KB PTEs */
-                if (target_page_bits)
-                    *target_page_bits = TARGET_PAGE_BITS;
-            }
-            if ((eaddr & mask) == (slb->tmp64 & mask)) {
-                /* SLB match */
-                *vsid = ((slb->tmp64 << 24) | (slb->tmp >> 8)) & 0x0003FFFFFFFFFFFFULL;
-                *page_mask = ~mask;
-                *attr = slb->tmp & 0xFF;
-                ret = n;
-                break;
+        ppc_slb_t *slb = &env->slb[n];
+
+        LOG_SLB("%s: slot %d %016" PRIx64 " %016"
+                    PRIx64 "\n", __func__, n, slb->esid, slb->vsid);
+        if (slb->esid == esid) {
+            *vsid = (slb->vsid & SLB_VSID_VSID) >> SLB_VSID_SHIFT;
+            *page_mask = ~SEGMENT_MASK_256M;
+            *attr = slb->vsid & SLB_VSID_ATTR;
+            if (target_page_bits) {
+                *target_page_bits = (slb->vsid & SLB_VSID_L)
+                    ? TARGET_PAGE_BITS_16M
+                    : TARGET_PAGE_BITS;
             }
+            return n;
         }
     }
 
-    return ret;
+    return -5;
 }
 
 void ppc_slb_invalidate_all (CPUPPCState *env)
@@ -760,11 +711,10 @@ void ppc_slb_invalidate_all (CPUPPCState *env)
     do_invalidate = 0;
     /* XXX: Warning: slbia never invalidates the first segment */
     for (n = 1; n < env->slb_nr; n++) {
-        ppc_slb_t *slb = slb_get_entry(env, n);
+        ppc_slb_t *slb = &env->slb[n];
 
-        if (slb_is_valid(slb)) {
-            slb_invalidate(slb);
-            slb_set_entry(env, n, slb);
+        if (slb->esid & SLB_ESID_V) {
+            slb->esid &= ~SLB_ESID_V;
             /* XXX: given the fact that segment size is 256 MB or 1TB,
              *      and we still don't have a tlb_flush_mask(env, n, mask)
              *      in Qemu, we just invalidate all TLBs
@@ -781,68 +731,44 @@ void ppc_slb_invalidate_one (CPUPPCState *env, uint64_t T0)
     target_ulong vsid, page_mask;
     int attr;
     int n;
+    ppc_slb_t *slb;
 
     n = slb_lookup(env, T0, &vsid, &page_mask, &attr, NULL);
-    if (n >= 0) {
-        ppc_slb_t *slb = slb_get_entry(env, n);
-
-        if (slb_is_valid(slb)) {
-            slb_invalidate(slb);
-            slb_set_entry(env, n, slb);
-            /* XXX: given the fact that segment size is 256 MB or 1TB,
-             *      and we still don't have a tlb_flush_mask(env, n, mask)
-             *      in Qemu, we just invalidate all TLBs
-             */
-            tlb_flush(env, 1);
-        }
+    if (n < 0) {
+        return;
     }
-}
 
-target_ulong ppc_load_slb (CPUPPCState *env, int slb_nr)
-{
-    target_ulong rt;
-    ppc_slb_t *slb = slb_get_entry(env, slb_nr);
+    slb = &env->slb[n];
 
-    if (slb_is_valid(slb)) {
-        /* SLB entry is valid */
-        /* Copy SLB bits 62:88 to Rt 37:63 (VSID 23:49) */
-        rt = slb->tmp >> 8;             /* 65:88 => 40:63 */
-        rt |= (slb->tmp64 & 0x7) << 24; /* 62:64 => 37:39 */
-        /* Copy SLB bits 89:92 to Rt 33:36 (KsKpNL) */
-        rt |= ((slb->tmp >> 4) & 0xF) << 27;
-    } else {
-        rt = 0;
-    }
-    LOG_SLB("%s: %016" PRIx64 " %08" PRIx32 " => %d "
-            TARGET_FMT_lx "\n", __func__, slb->tmp64, slb->tmp, slb_nr, rt);
+    if (slb->esid & SLB_ESID_V) {
+        slb->esid &= ~SLB_ESID_V;
 
-    return rt;
+        /* XXX: given the fact that segment size is 256 MB or 1TB,
+         *      and we still don't have a tlb_flush_mask(env, n, mask)
+         *      in Qemu, we just invalidate all TLBs
+         */
+        tlb_flush(env, 1);
+    }
 }
 
-void ppc_store_slb (CPUPPCState *env, target_ulong rb, target_ulong rs)
+int ppc_store_slb (CPUPPCState *env, target_ulong rb, target_ulong rs)
 {
-    ppc_slb_t *slb;
-
-    uint64_t vsid;
-    uint64_t esid;
-    int flags, valid, slb_nr;
-
-    vsid = rs >> 12;
-    flags = ((rs >> 8) & 0xf);
+    int slot = rb & 0xfff;
+    uint64_t esid = rb & ~0xfff;
+    ppc_slb_t *slb = &env->slb[slot];
 
-    esid = rb >> 28;
-    valid = (rb & (1 << 27));
-    slb_nr = rb & 0xfff;
+    if (slot >= env->slb_nr) {
+        return -1;
+    }
 
-    slb = slb_get_entry(env, slb_nr);
-    slb->tmp64 = (esid << 28) | valid | (vsid >> 24);
-    slb->tmp = (vsid << 8) | (flags << 3);
+    slb->esid = esid;
+    slb->vsid = rs;
 
     LOG_SLB("%s: %d " TARGET_FMT_lx " - " TARGET_FMT_lx " => %016" PRIx64
-            " %08" PRIx32 "\n", __func__, slb_nr, rb, rs, slb->tmp64,
-            slb->tmp);
+            " %016" PRIx64 "\n", __func__, slot, rb, rs,
+            slb->esid, slb->vsid);
 
-    slb_set_entry(env, slb_nr, slb);
+    return 0;
 }
 #endif /* defined(TARGET_PPC64) */
 
@@ -860,24 +786,22 @@ static inline int get_segment(CPUState *env, mmu_ctx_t *ctx,
 {
     target_phys_addr_t sdr, hash, mask, sdr_mask, htab_mask;
     target_ulong sr, vsid, vsid_mask, pgidx, page_mask;
-#if defined(TARGET_PPC64)
-    int attr;
-#endif
     int ds, vsid_sh, sdr_sh, pr, target_page_bits;
     int ret, ret2;
 
     pr = msr_pr;
 #if defined(TARGET_PPC64)
     if (env->mmu_model & POWERPC_MMU_64) {
+        int attr;
+
         LOG_MMU("Check SLBs\n");
         ret = slb_lookup(env, eaddr, &vsid, &page_mask, &attr,
                          &target_page_bits);
         if (ret < 0)
             return ret;
-        ctx->key = ((attr & 0x40) && (pr != 0)) ||
-            ((attr & 0x80) && (pr == 0)) ? 1 : 0;
+        ctx->key = !!(pr ? (attr & SLB_VSID_KP) : (attr & SLB_VSID_KS));
         ds = 0;
-        ctx->nx = attr & 0x10 ? 1 : 0;
+        ctx->nx = !!(attr & SLB_VSID_N);
         ctx->eaddr = eaddr;
         vsid_mask = 0x00003FFFFFFFFF80ULL;
         vsid_sh = 7;
diff --git a/target-ppc/helper.h b/target-ppc/helper.h
index 2bf9283..d512cb0 100644
--- a/target-ppc/helper.h
+++ b/target-ppc/helper.h
@@ -340,7 +340,6 @@ DEF_HELPER_1(74xx_tlbi, void, tl)
 DEF_HELPER_FLAGS_0(tlbia, TCG_CALL_CONST, void)
 DEF_HELPER_FLAGS_1(tlbie, TCG_CALL_CONST, void, tl)
 #if defined(TARGET_PPC64)
-DEF_HELPER_FLAGS_1(load_slb, TCG_CALL_CONST, tl, tl)
 DEF_HELPER_FLAGS_2(store_slb, TCG_CALL_CONST, void, tl, tl)
 DEF_HELPER_FLAGS_0(slbia, TCG_CALL_CONST, void)
 DEF_HELPER_FLAGS_1(slbie, TCG_CALL_CONST, void, tl)
diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
index 17e070a..bf41627 100644
--- a/target-ppc/op_helper.c
+++ b/target-ppc/op_helper.c
@@ -3746,14 +3746,11 @@ void helper_store_sr (target_ulong sr_num, target_ulong val)
 
 /* SLB management */
 #if defined(TARGET_PPC64)
-target_ulong helper_load_slb (target_ulong slb_nr)
-{
-    return ppc_load_slb(env, slb_nr);
-}
-
 void helper_store_slb (target_ulong rb, target_ulong rs)
 {
-    ppc_store_slb(env, rb, rs);
+    if (ppc_store_slb(env, rb, rs) < 0) {
+        helper_raise_exception_err(POWERPC_EXCP_PROGRAM, POWERPC_EXCP_INVAL);
+    }
 }
 
 void helper_slbia (void)
-- 
1.7.1