From b362e5e067835d04ddde5fb1277272d4b498b970 Mon Sep 17 00:00:00 2001
From: pbrook <pbrook@c046a42c-6fe2-441c-8c8c-71466251a162>
Date: Sun, 12 Nov 2006 20:40:55 +0000
Subject: [PATCH] Speed up tlb_flush_page (Daniel Jacobowitz).

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2210 c046a42c-6fe2-441c-8c8c-71466251a162
---
 cpu-defs.h |  8 ++++++++
 exec-all.h | 12 +++++++++++-
 exec.c     | 15 +++++++--------
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/cpu-defs.h b/cpu-defs.h
index 674c0bd..0b49c89 100644
--- a/cpu-defs.h
+++ b/cpu-defs.h
@@ -80,6 +80,14 @@ typedef unsigned long ram_addr_t;
 #define TB_JMP_CACHE_BITS 12
 #define TB_JMP_CACHE_SIZE (1 << TB_JMP_CACHE_BITS)
 
+/* Only the bottom TB_JMP_PAGE_BITS of the jump cache hash bits vary for
+   addresses on the same page.  The top bits are the same.  This allows
+   TLB invalidation to quickly clear a subset of the hash table.  */
+#define TB_JMP_PAGE_BITS (TB_JMP_CACHE_BITS / 2)
+#define TB_JMP_PAGE_SIZE (1 << TB_JMP_PAGE_BITS)
+#define TB_JMP_ADDR_MASK (TB_JMP_PAGE_SIZE - 1)
+#define TB_JMP_PAGE_MASK (TB_JMP_CACHE_SIZE - TB_JMP_PAGE_SIZE)
+
 #define CPU_TLB_BITS 8
 #define CPU_TLB_SIZE (1 << CPU_TLB_BITS)
 
diff --git a/exec-all.h b/exec-all.h
index b598948..82ef3ac 100644
--- a/exec-all.h
+++ b/exec-all.h
@@ -196,9 +196,19 @@ typedef struct TranslationBlock {
     struct TranslationBlock *jmp_first;
 } TranslationBlock;
 
+static inline unsigned int tb_jmp_cache_hash_page(target_ulong pc)
+{
+    target_ulong tmp;
+    tmp = pc ^ (pc >> (TARGET_PAGE_BITS - TB_JMP_PAGE_BITS));
+    return (tmp >> TB_JMP_PAGE_BITS) & TB_JMP_PAGE_MASK;
+}
+
 static inline unsigned int tb_jmp_cache_hash_func(target_ulong pc)
 {
-    return (pc ^ (pc >> TB_JMP_CACHE_BITS)) & (TB_JMP_CACHE_SIZE - 1);
+    target_ulong tmp;
+    tmp = pc ^ (pc >> (TARGET_PAGE_BITS - TB_JMP_PAGE_BITS));
+    return (((tmp >> TB_JMP_PAGE_BITS) & TB_JMP_PAGE_MASK) |
+	    (tmp & TB_JMP_ADDR_MASK));
 }
 
 static inline unsigned int tb_phys_hash_func(unsigned long pc)
diff --git a/exec.c b/exec.c
index 20870ad..762d6dc 100644
--- a/exec.c
+++ b/exec.c
@@ -1288,14 +1288,13 @@ void tlb_flush_page(CPUState *env, target_ulong addr)
     tlb_flush_entry(&env->tlb_table[0][i], addr);
     tlb_flush_entry(&env->tlb_table[1][i], addr);
 
-    for(i = 0; i < TB_JMP_CACHE_SIZE; i++) {
-        tb = env->tb_jmp_cache[i];
-        if (tb && 
-            ((tb->pc & TARGET_PAGE_MASK) == addr ||
-             ((tb->pc + tb->size - 1) & TARGET_PAGE_MASK) == addr)) {
-            env->tb_jmp_cache[i] = NULL;
-        }
-    }
+    /* Discard jump cache entries for any tb which might potentially
+       overlap the flushed page.  */
+    i = tb_jmp_cache_hash_page(addr - TARGET_PAGE_SIZE);
+    memset (&env->tb_jmp_cache[i], 0, TB_JMP_PAGE_SIZE * sizeof(tb));
+
+    i = tb_jmp_cache_hash_page(addr);
+    memset (&env->tb_jmp_cache[i], 0, TB_JMP_PAGE_SIZE * sizeof(tb));
 
 #if !defined(CONFIG_SOFTMMU)
     if (addr < MMAP_AREA_END)
-- 
2.7.4