replay: interrupts and exceptions

This patch includes modifications of common cpu files. All interrupts and
exceptions occured during recording are written into the replay log.
These events allow correct replaying the execution by kicking cpu thread
when one of these events is found in the log.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20150917162416.8676.57647.stgit@PASHA-ISP.def.inno>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 146 insertions, 10 deletions

diff --git a/cpu-exec.c b/cpu-exec.c
index a1e3d58..a57b388 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -30,6 +30,7 @@
 #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
 #include "hw/i386/apic.h"
 #endif
+#include "sysemu/replay.h"
 
 /* -icount align implementation. */
 
@@ -346,21 +347,25 @@ int cpu_exec(CPUState *cpu)
     uintptr_t next_tb;
     SyncClocks sc;
 
+    /* replay_interrupt may need current_cpu */
+    current_cpu = cpu;
+
     if (cpu->halted) {
 #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
-        if (cpu->interrupt_request & CPU_INTERRUPT_POLL) {
+        if ((cpu->interrupt_request & CPU_INTERRUPT_POLL)
+            && replay_interrupt()) {
             apic_poll_irq(x86_cpu->apic_state);
             cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
         }
 #endif
         if (!cpu_has_work(cpu)) {
+            current_cpu = NULL;
             return EXCP_HALTED;
         }
 
         cpu->halted = 0;
     }
 
-    current_cpu = cpu;
     atomic_mb_set(&tcg_current_cpu, cpu);
     rcu_read_lock();
 
@@ -402,10 +407,22 @@ int cpu_exec(CPUState *cpu)
                     cpu->exception_index = -1;
                     break;
 #else
-                    cc->do_interrupt(cpu);
-                    cpu->exception_index = -1;
+                    if (replay_exception()) {
+                        cc->do_interrupt(cpu);
+                        cpu->exception_index = -1;
+                    } else if (!replay_has_interrupt()) {
+                        /* give a chance to iothread in replay mode */
+                        ret = EXCP_INTERRUPT;
+                        break;
+                    }
 #endif
                 }
+            } else if (replay_has_exception()
+                       && cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
+                /* try to cause an exception pending in the log */
+                cpu_exec_nocache(cpu, 1, tb_find_fast(cpu), true);
+                ret = -1;
+                break;
             }
 
             next_tb = 0; /* force lookup of first TB */
@@ -421,30 +438,40 @@ int cpu_exec(CPUState *cpu)
                         cpu->exception_index = EXCP_DEBUG;
                         cpu_loop_exit(cpu);
                     }
-                    if (interrupt_request & CPU_INTERRUPT_HALT) {
+                    if (replay_mode == REPLAY_MODE_PLAY
+                        && !replay_has_interrupt()) {
+                        /* Do nothing */
+                    } else if (interrupt_request & CPU_INTERRUPT_HALT) {
+                        replay_interrupt();
                         cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
                         cpu->halted = 1;
                         cpu->exception_index = EXCP_HLT;
                         cpu_loop_exit(cpu);
                     }
 #if defined(TARGET_I386)
-                    if (interrupt_request & CPU_INTERRUPT_INIT) {
+                    else if (interrupt_request & CPU_INTERRUPT_INIT) {
+                        replay_interrupt();
                         cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0);
                         do_cpu_init(x86_cpu);
                         cpu->exception_index = EXCP_HALTED;
                         cpu_loop_exit(cpu);
                     }
 #else
-                    if (interrupt_request & CPU_INTERRUPT_RESET) {
+                    else if (interrupt_request & CPU_INTERRUPT_RESET) {
+                        replay_interrupt();
                         cpu_reset(cpu);
+                        cpu_loop_exit(cpu);
                     }
 #endif
                     /* The target hook has 3 exit conditions:
                        False when the interrupt isn't processed,
                        True when it is, and we should restart on a new TB,
                        and via longjmp via cpu_loop_exit.  */
-                    if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
-                        next_tb = 0;
+                    else {
+                        replay_interrupt();
+                        if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
+                            next_tb = 0;
+                        }
                     }
                     /* Don't use the cached interrupt_request value,
                        do_interrupt may have updated the EXITTB flag. */
@@ -455,7 +482,8 @@ int cpu_exec(CPUState *cpu)
                         next_tb = 0;
                     }
                 }
-                if (unlikely(cpu->exit_request)) {
+                if (unlikely(cpu->exit_request
+                             || replay_has_interrupt())) {
                     cpu->exit_request = 0;
                     cpu->exception_index = EXCP_INTERRUPT;
                     cpu_loop_exit(cpu);
diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
index d19715f..8915523 100644
--- a/include/sysemu/replay.h
+++ b/include/sysemu/replay.h
@@ -27,4 +27,21 @@ int replay_get_instructions(void);
 /*! Updates instructions counter in replay mode. */
 void replay_account_executed_instructions(void);
 
+/* Interrupts and exceptions */
+
+/*! Called by exception handler to write or read
+    exception processing events. */
+bool replay_exception(void);
+/*! Used to determine that exception is pending.
+    Does not proceed to the next event in the log. */
+bool replay_has_exception(void);
+/*! Called by interrupt handlers to write or read
+    interrupt processing events.
+    \return true if interrupt should be processed */
+bool replay_interrupt(void);
+/*! Tries to read interrupt event from the file.
+    Returns true, when interrupt request is pending */
+bool replay_has_interrupt(void);
+
+
 #endif
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index ff4fabc..5ff1c14 100644
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -17,6 +17,10 @@
 enum ReplayEvents {
     /* for instruction event */
     EVENT_INSTRUCTION,
+    /* for software interrupt */
+    EVENT_INTERRUPT,
+    /* for emulated exceptions */
+    EVENT_EXCEPTION,
     EVENT_COUNT
 };
 
diff --git a/replay/replay.c b/replay/replay.c
index b2c6750..b4fc64a 100644
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -79,3 +79,70 @@ void replay_account_executed_instructions(void)
         replay_mutex_unlock();
     }
 }
+
+bool replay_exception(void)
+{
+    if (replay_mode == REPLAY_MODE_RECORD) {
+        replay_save_instructions();
+        replay_mutex_lock();
+        replay_put_event(EVENT_EXCEPTION);
+        replay_mutex_unlock();
+        return true;
+    } else if (replay_mode == REPLAY_MODE_PLAY) {
+        bool res = replay_has_exception();
+        if (res) {
+            replay_mutex_lock();
+            replay_finish_event();
+            replay_mutex_unlock();
+        }
+        return res;
+    }
+
+    return true;
+}
+
+bool replay_has_exception(void)
+{
+    bool res = false;
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        replay_account_executed_instructions();
+        replay_mutex_lock();
+        res = replay_next_event_is(EVENT_EXCEPTION);
+        replay_mutex_unlock();
+    }
+
+    return res;
+}
+
+bool replay_interrupt(void)
+{
+    if (replay_mode == REPLAY_MODE_RECORD) {
+        replay_save_instructions();
+        replay_mutex_lock();
+        replay_put_event(EVENT_INTERRUPT);
+        replay_mutex_unlock();
+        return true;
+    } else if (replay_mode == REPLAY_MODE_PLAY) {
+        bool res = replay_has_interrupt();
+        if (res) {
+            replay_mutex_lock();
+            replay_finish_event();
+            replay_mutex_unlock();
+        }
+        return res;
+    }
+
+    return true;
+}
+
+bool replay_has_interrupt(void)
+{
+    bool res = false;
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        replay_account_executed_instructions();
+        replay_mutex_lock();
+        res = replay_next_event_is(EVENT_INTERRUPT);
+        replay_mutex_unlock();
+    }
+    return res;
+}
diff --git a/stubs/replay-user.c b/stubs/replay-user.c
index 0c90bfc..cf33072 100644
--- a/stubs/replay-user.c
+++ b/stubs/replay-user.c
@@ -10,3 +10,23 @@
  */
 
 #include "sysemu/replay.h"
+
+bool replay_exception(void)
+{
+    return true;
+}
+
+bool replay_has_exception(void)
+{
+    return false;
+}
+
+bool replay_interrupt(void)
+{
+    return true;
+}
+
+bool replay_has_interrupt(void)
+{
+    return false;
+}