[Qemu-devel] [RFC PATCH v5 17/31] replay: interrupts and exceptions

[Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>]

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>
---
 cpu-exec.c               |   33 +++++++++++++++++++++++------
 replay/replay-internal.h |    4 +++
 replay/replay.c          |   53 ++++++++++++++++++++++++++++++++++++++++++++++
 replay/replay.h          |   17 +++++++++++++++
 4 files changed, 100 insertions(+), 7 deletions(-)

diff --git a/cpu-exec.c b/cpu-exec.c
index 65cbeb7..05cca50 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -24,6 +24,7 @@
 #include "qemu/atomic.h"
 #include "sysemu/qtest.h"
 #include "qemu/timer.h"
+#include "replay/replay.h"
 
 /* -icount align implementation. */
 
@@ -391,10 +392,21 @@ int cpu_exec(CPUArchState *env)
                     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(env, 1, tb_find_fast(env), true);
+                break;
             }
 
             next_tb = 0; /* force lookup of first TB */
@@ -410,21 +422,24 @@ int cpu_exec(CPUArchState *env)
                         cpu->exception_index = EXCP_DEBUG;
                         cpu_loop_exit(cpu);
                     }
-                    if (interrupt_request & CPU_INTERRUPT_HALT) {
+                    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) {
+                    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) {
+                    if ((interrupt_request & CPU_INTERRUPT_RESET)
+                        && replay_interrupt()) {
                         cpu_reset(cpu);
                     }
 #endif
@@ -432,7 +447,10 @@ int cpu_exec(CPUArchState *env)
                        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)) {
+                    if ((replay_mode != REPLAY_MODE_PLAY
+                            || replay_has_interrupt())
+                        && cc->cpu_exec_interrupt(cpu, interrupt_request)) {
+                        replay_interrupt();
                         next_tb = 0;
                     }
                     /* Don't use the cached interrupt_request value,
@@ -444,7 +462,8 @@ int cpu_exec(CPUArchState *env)
                         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/replay/replay-internal.h b/replay/replay-internal.h
index 582b44c..fd5c230 100755
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -14,6 +14,10 @@
 
 #include <stdio.h>
 
+/* for software interrupt */
+#define EVENT_INTERRUPT             15
+/* for emulated exceptions */
+#define EVENT_EXCEPTION             23
 /* for instruction event */
 #define EVENT_INSTRUCTION           32
 
diff --git a/replay/replay.c b/replay/replay.c
index c305e0c..c275794 100755
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -68,3 +68,56 @@ uint64_t replay_get_current_step(void)
 {
     return cpu_get_instructions_counter();
 }
+
+bool replay_exception(void)
+{
+    if (replay_mode == REPLAY_MODE_RECORD) {
+        replay_save_instructions();
+        replay_put_event(EVENT_EXCEPTION);
+        return true;
+    } else if (replay_mode == REPLAY_MODE_PLAY) {
+        if (skip_async_events(EVENT_EXCEPTION)) {
+            replay_has_unread_data = 0;
+            return true;
+        }
+        return false;
+    }
+
+    return true;
+}
+
+bool replay_has_exception(void)
+{
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        if (skip_async_events(EVENT_EXCEPTION)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+bool replay_interrupt(void)
+{
+    if (replay_mode == REPLAY_MODE_RECORD) {
+        replay_save_instructions();
+        replay_put_event(EVENT_INTERRUPT);
+        return true;
+    } else if (replay_mode == REPLAY_MODE_PLAY) {
+        if (skip_async_events(EVENT_INTERRUPT)) {
+            replay_has_unread_data = 0;
+            return true;
+        }
+        return false;
+    }
+
+    return true;
+}
+
+bool replay_has_interrupt(void)
+{
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        return skip_async_events(EVENT_INTERRUPT);
+    }
+    return false;
+}
diff --git a/replay/replay.h b/replay/replay.h
index e40daf5..d7abaee 100755
--- a/replay/replay.h
+++ b/replay/replay.h
@@ -27,4 +27,21 @@ ReplaySubmode replay_get_play_submode(void);
 /*! Returns number of executed instructions. */
 uint64_t replay_get_current_step(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