i386: do not cross the pages boundaries in replay mode

This patch denies crossing the boundary of the pages in the replay mode,
because it can cause an exception. Do it only when boundary is
crossed by the first instruction in the block.
If current instruction already crossed the bound - it's ok,
because an exception hasn't stopped this code.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 7e363654b8efce198f99d744ae3302ec505bb835..3ecff9632504dff1fc72643bf56cce975be5bbea 100644 (file)
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -28,6 +28,9 @@
 #define TARGET_LONG_BITS 32
 #endif
 
+/* Maximum instruction code size */
+#define TARGET_MAX_INSN_SIZE 16
+
 /* target supports implicit self modifying code */
 #define TARGET_HAS_SMC
 /* support for self modifying code even if the modified instruction is

diff --git a/target-i386/translate.c b/target-i386/translate.c
index 782f7d266663d5dd8d99bff00540829bbfe17d37..31a9f74467289e842cbce7c76dc38cdcf8c603aa 100644 (file)
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -8022,6 +8022,20 @@ static inline void gen_intermediate_code_internal(X86CPU *cpu,
             gen_eob(dc);
             break;
         }
+        /* Do not cross the boundary of the pages in icount mode,
+           it can cause an exception. Do it only when boundary is
+           crossed by the first instruction in the block.
+           If current instruction already crossed the bound - it's ok,
+           because an exception hasn't stopped this code.
+         */
+        if (use_icount
+            && ((pc_ptr & TARGET_PAGE_MASK)
+                != ((pc_ptr + TARGET_MAX_INSN_SIZE - 1) & TARGET_PAGE_MASK)
+                || (pc_ptr & ~TARGET_PAGE_MASK) == 0)) {
+            gen_jmp_im(pc_ptr - dc->cs_base);
+            gen_eob(dc);
+            break;
+        }
         /* if too long translation, stop generation too */
         if (tcg_ctx.gen_opc_ptr >= gen_opc_end ||
             (pc_ptr - pc_start) >= (TARGET_PAGE_SIZE - 32) ||