[Qemu-devel] [PATCH] gdbstub improvements for gdb kill/detach/quit

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

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Attached is a patch to improve the gdb stub 'D' 'k' and '?' packets. 
See the patch header for details.

Jason.

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From: Jason Wessel <jason.wessel@windriver.com>
Subject: [PATCH] support for gdb "detach/kill/quit"

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 function to cleanup all the breakpoints
prior to leaving the gdb stub else simulation can stop with no
debugger attached.

On a '?' packet remove all the breakpoints.  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 |    1 +
 exec.c    |   14 ++++++++++++++
 gdbstub.c |   16 ++++++++++++++++
 3 files changed, 31 insertions(+)

--- a/cpu-all.h
+++ b/cpu-all.h
@@ -759,6 +759,7 @@ void cpu_interrupt(CPUState *s, int mask
 void cpu_reset_interrupt(CPUState *env, int mask);
 
 int cpu_watchpoint_insert(CPUState *env, target_ulong addr);
+int cpu_breakpoint_remove_all(CPUState *env);
 int cpu_watchpoint_remove(CPUState *env, target_ulong addr);
 int cpu_breakpoint_insert(CPUState *env, target_ulong pc);
 int cpu_breakpoint_remove(CPUState *env, target_ulong pc);
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -901,6 +901,11 @@ static int gdb_handle_packet(GDBState *s
         /* 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);
         break;
     case 'c':
         if (*p != '\0') {
@@ -924,6 +929,17 @@ static int gdb_handle_packet(GDBState *s
         }
         gdb_continue(s);
 	return RS_IDLE;
+    case 'k':
+        /* Kill the target */
+        fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
+        exit(0);
+    case 'D':
+        /* Detach packet */
+        if (!cpu_breakpoint_remove_all(env)) {
+            gdb_continue(s);
+            put_packet(s, "OK");
+            break;
+        }
     case 's':
         if (*p != '\0') {
             addr = strtoull(p, (char **)&p, 16);
--- a/exec.c
+++ b/exec.c
@@ -1150,6 +1150,20 @@ int cpu_breakpoint_insert(CPUState *env,
 #endif
 }
 
+/* remove all breakpoints */
+int 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;
+    return 0;
+#else
+    return -1;
+#endif
+}
+
 /* remove a breakpoint */
 int cpu_breakpoint_remove(CPUState *env, target_ulong pc)
 {