[Qemu-devel] [PATCH 4/5] gdbstub: support for gdb "detach/kill/quit"

[Jason Wessel <jason.wessel@windriver.com>]

Implement the 'k' gdbserial packet which kills the qemu instance via
the debugger stub.

Implement the 'D' detach packet for the gdb stub such that you can
disconnect gdb with the "detach" command.  This required implementing
a cpu_breakpoint_remove_all() and a cpu_watchpoint_remove_all()
function to cleanup all the breakpoints and watchpoints prior to
leaving the gdb stub else simulation can stop with no debugger
attached.

On a '?' packet remove all the breakpoints and watchpoints.  This is
considered more of a safety net in case you force killed gdb or it
crashed and you are reconnecting.  The identical behavior exists for
kgdb in the linux kernel.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
 cpu-all.h |    2 ++
 exec.c    |   21 +++++++++++++++++++++
 gdbstub.c |   17 +++++++++++++++++
 3 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/cpu-all.h b/cpu-all.h
index 7e77f76..d71166c 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -760,8 +760,10 @@ void cpu_reset_interrupt(CPUState *env, int mask);
 
 int cpu_watchpoint_insert(CPUState *env, target_ulong addr);
 int cpu_watchpoint_remove(CPUState *env, target_ulong addr);
+void cpu_watchpoint_remove_all(CPUState *env);
 int cpu_breakpoint_insert(CPUState *env, target_ulong pc);
 int cpu_breakpoint_remove(CPUState *env, target_ulong pc);
+void cpu_breakpoint_remove_all(CPUState *env);
 
 #define SSTEP_ENABLE  0x1  /* Enable simulated HW single stepping */
 #define SSTEP_NOIRQ   0x2  /* Do not use IRQ while single stepping */
diff --git a/exec.c b/exec.c
index 2fd0078..8f5c868 100644
--- a/exec.c
+++ b/exec.c
@@ -1139,6 +1139,16 @@ int cpu_watchpoint_remove(CPUState *env, target_ulong addr)
     return -1;
 }
 
+/* Remove all watchpoints. */
+void cpu_watchpoint_remove_all(CPUState *env) {
+    int i;
+
+    for (i = 0; i < env->nb_watchpoints; i++) {
+        tlb_flush_page(env, env->watchpoint[i].vaddr);
+    }
+    env->nb_watchpoints = 0;
+}
+
 /* add a breakpoint. EXCP_DEBUG is returned by the CPU loop if a
    breakpoint is reached */
 int cpu_breakpoint_insert(CPUState *env, target_ulong pc)
@@ -1162,6 +1172,17 @@ int cpu_breakpoint_insert(CPUState *env, target_ulong pc)
 #endif
 }
 
+/* remove all breakpoints */
+void cpu_breakpoint_remove_all(CPUState *env) {
+#if defined(TARGET_HAS_ICE)
+    int i;
+    for(i = 0; i < env->nb_breakpoints; i++) {
+        breakpoint_invalidate(env, env->breakpoints[i]);
+    }
+    env->nb_breakpoints = 0;
+#endif
+}
+
 /* remove a breakpoint */
 int cpu_breakpoint_remove(CPUState *env, target_ulong pc)
 {
diff --git a/gdbstub.c b/gdbstub.c
index 833cdd9..fb2d948 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -1035,6 +1035,12 @@ static int gdb_handle_packet(GDBState *s, CPUState *env, const char *line_buf)
         /* TODO: Make this return the correct value for user-mode.  */
         snprintf(buf, sizeof(buf), "S%02x", SIGTRAP);
         put_packet(s, buf);
+        /* Remove all the breakpoints when this query is issued,
+         * because gdb is doing and initial connect and the state
+         * should be cleaned up.
+         */
+        cpu_breakpoint_remove_all(env);
+        cpu_watchpoint_remove_all(env);
         break;
     case 'c':
         if (*p != '\0') {
@@ -1058,6 +1064,17 @@ static int gdb_handle_packet(GDBState *s, CPUState *env, const char *line_buf)
         }
         gdb_continue(s);
 	return RS_IDLE;
+    case 'k':
+        /* Kill the target */
+        fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
+        exit(0);
+    case 'D':
+        /* Detach packet */
+        cpu_breakpoint_remove_all(env);
+        cpu_watchpoint_remove_all(env);
+        gdb_continue(s);
+        put_packet(s, "OK");
+        break;
     case 's':
         if (*p != '\0') {
             addr = strtoull(p, (char **)&p, 16);
-- 
1.5.5.1