From patchwork Thu May  6 05:36:59 2010
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Subject: A bit optimization for tlb_set_page() (resend)
Date: Wed, 05 May 2010 19:36:59 -0000
From: Jun Koi <junkoi2004@gmail.com>
X-Patchwork-Id: 51835
Message-Id: <v2zfdaac4d51005052236o40c1cd47kf871bf7649915a62@mail.gmail.com>
To: qemu-devel@nongnu.org, Jan Kiszka <jan.kiszka@web.de>
Cc: 

This patch avoids handling write watchpoints on read-only memory access.
It also breaks the searching loop for watchpoint once the setup for
handling watchpoint later is done.

Signed-off-by: Jun Koi <junkoi2004@gmail.com>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>


diff --git a/exec.c b/exec.c
index 14d1fd7..6fd859f 100644
--- a/exec.c
+++ b/exec.c
@@ -2236,10 +2236,12 @@ void tlb_set_page(CPUState *env, target_ulong vaddr,
        watchpoint trap routines.  */
     QTAILQ_FOREACH(wp, &env->watchpoints, entry) {
         if (vaddr == (wp->vaddr & TARGET_PAGE_MASK)) {
-            iotlb = io_mem_watch + paddr;
-            /* TODO: The memory case can be optimized by not trapping
-               reads of pages with a write breakpoint.  */
-            address |= TLB_MMIO;
+            /* Avoid trapping reads of pages with a write breakpoint. */
+            if ((prot & PAGE_WRITE) || (wp->flags & BP_MEM_READ)) {
+                iotlb = io_mem_watch + paddr;
+                address |= TLB_MMIO;
+                break;
+            }
         }
     }