cpu-exec: allow temporary disabling icount

This patch is required for deterministic replay to generate an exception
by trying executing an instruction without changing icount.
It adds new flag to TB for disabling icount while translating it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20150917162359.8676.77011.stgit@PASHA-ISP.def.inno>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/cpu-exec.c b/cpu-exec.c
index 7eef0830fe8f55bab2a022e0a03703c197abe0f7..a1e3d58692f5d4e099a9207ce10fe4a2664b2a60 100644 (file)
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -184,7 +184,7 @@ static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr)
 /* Execute the code without caching the generated code. An interpreter
    could be used if available. */
 static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
-                             TranslationBlock *orig_tb)
+                             TranslationBlock *orig_tb, bool ignore_icount)
 {
     TranslationBlock *tb;
 
@@ -194,7 +194,8 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
         max_cycles = CF_COUNT_MASK;
 
     tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
-                     max_cycles | CF_NOCACHE);
+                     max_cycles | CF_NOCACHE
+                         | (ignore_icount ? CF_IGNORE_ICOUNT : 0));
     tb->orig_tb = tcg_ctx.tb_ctx.tb_invalidated_flag ? NULL : orig_tb;
     cpu->current_tb = tb;
     /* execute the generated code */
@@ -519,7 +520,7 @@ int cpu_exec(CPUState *cpu)
                             if (insns_left > 0) {
                                 /* Execute remaining instructions.  */
                                 tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
-                                cpu_exec_nocache(cpu, insns_left, tb);
+                                cpu_exec_nocache(cpu, insns_left, tb, false);
                                 align_clocks(&sc, cpu);
                             }
                             cpu->exception_index = EXCP_INTERRUPT;

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 9b93b9b47d2ccce52537d7cd34171ec9146b55fc..b07de109fb830683d603c5ba8e5265eec8830837 100644 (file)
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -190,6 +190,7 @@ struct TranslationBlock {
 #define CF_LAST_IO     0x8000 /* Last insn may be an IO access.  */
 #define CF_NOCACHE     0x10000 /* To be freed after execution */
 #define CF_USE_ICOUNT  0x20000
+#define CF_IGNORE_ICOUNT 0x40000 /* Do not generate icount code */
 
     void *tc_ptr;    /* pointer to the translated code */
     uint8_t *tc_search;  /* pointer to search data */

diff --git a/translate-all.c b/translate-all.c
index 20ce40ec28b45b7bedc9de2fdafe65fd210c229f..a940bd2e5e8200670b498092b0c984fbcb36ceb0 100644 (file)
--- a/translate-all.c
+++ b/translate-all.c
@@ -1069,7 +1069,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
 #endif
 
     phys_pc = get_page_addr_code(env, pc);
-    if (use_icount) {
+    if (use_icount && !(cflags & CF_IGNORE_ICOUNT)) {
         cflags |= CF_USE_ICOUNT;
     }