Patchwork [35/45] mmu-hash32: Don't look up page tables on BAT permission error

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Submitter David Gibson
Date March 6, 2013, 3:44 a.m.
Message ID <1362541473-4365-36-git-send-email-david@gibson.dropbear.id.au>
Download mbox | patch
Permalink /patch/225297/
State New
Headers show

Comments

David Gibson - March 6, 2013, 3:44 a.m.
BEHAVIOUR CHANGE

Currently, on any failure translating an address with BATs, we proceed to
normal segment and page table translation.  That's incorrect if the
BAT error was due to permissions, rather than not finding a matching BAT.
We've gotten away with it because a guest would not usually put
translations for the same address in both BATs and page table.  Nonetheless
this patch corrects the logic, only doing page table lookup if no BAT
is found.  A matching BAT with bad permissions will now correctly trigger
an exception.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 target-ppc/mmu-hash32.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

Patch

diff --git a/target-ppc/mmu-hash32.c b/target-ppc/mmu-hash32.c
index d4d91dd..3488092 100644
--- a/target-ppc/mmu-hash32.c
+++ b/target-ppc/mmu-hash32.c
@@ -400,10 +400,7 @@  static int ppc_hash32_translate(CPUPPCState *env, struct mmu_ctx_hash32 *ctx,
     if (env->nb_BATs != 0) {
         ctx->raddr = ppc_hash32_bat_lookup(env, eaddr, rwx, &ctx->prot);
         if (ctx->raddr != -1) {
-            ret = ppc_hash32_check_prot(ctx->prot, rwx);
-            if (ret == 0) {
-                return 0;
-            }
+            return ppc_hash32_check_prot(ctx->prot, rwx);
         }
     }