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 7eef083..a1e3d58 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 9b93b9b..b07de10 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 20ce40e..a940bd2 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;
     }